BACKGROUND OF THE INVENTION

1 . Field of the Invention

[0001 ] The present invention relates to a driving support device and a driving support method.

2. Description of Related Art

[0002] Some vehicles such as automobiles have a driving support device installed therein for supporting driving of a driver. For example. Japanese Patent Application Publication No. 2010- 1 91 5 1 8 (JP 2010- 1 91 5 18 A) discloses a driving support device that supports travel of a vehicle so that the vehicle appropriately passes an intersection on the basis of the travel state of the vehicle and the traffic signal state. The driving support device determines whether a driver is advised to accelerate (to turn the accelerator ON ) the own vehicle and the own vehicle can thereby pass an intersection ahead where a traffic signal is provided (hereinafter referred to as "traffic signal intersection") at a green light. If it is determined that the driver is advised to accelerate the own vehicle and the own vehicle thereby can pass the traffic signal intersection ahead at a green light, an acceleration advice function by an acceleration indicator advises the driver to accelerate the own vehicle in an interval prior to the traffic signal intersection. If it is determined that although the driver is advised to accelerate the own vehicle, the own vehicle cannot pass the traffic signal intersection ahead at a green light, a red light entrance prevention function by an alarm advises the driver to decelerate or stop the own vehicle in the interval prior to the traffic signal intersection.

[0003] Japanese Patent Application Publication 2009-289007 (JP 2009-289007 A) discloses a vehicle travel speed indication method that comparatively indicates an actual travel speed of a vehicle in the form of a relative value with respect to a reference value with respect to a recommended travel speed or a corrected recommended travel speed as the reference value which is fixedly indicated on a display screen. [0004] The system disclosed in JP 2010- 1915 18 A or JP 2009-289007 A provides the advice indication for advising acceleration or the indication of the recommended travel speed and can thereby inform the driver of a travel condition in which the driver can pass the traffic signal. However, the system disclosed in JP 201 0- 191 51 8 A or JP 2009-289007 A may suggest an awkward travel condition to the driver. For example, in a case that the recommended travel speed is an awkward speed to the driver, the driver may hesitate to drive at the suggested recommended travel speed.

SUMMARY OF THE INVENTION

[0005] The present invention is to provide a driving support device and a driving support method that can reduce awkwardness experienced by a driver and can appropriately support driving.

[0006] A first aspect of the present invention provides a driving support device for supporting driving of a vehicle, the device including: an infrastructure communication section that obtains signal cycle information concerning switching among indications of the traffic signal, from the traffic signal which is disposed in a traveling direction of the vehicle; a position calculation section that calculates relative position information which represents a relative position between a traffic signal point at which the traffic signal is disposed and the vehicle; a target vehicle speed control section that calculates, as a reference target vehicle speed range, a speed range in which the vehicle can pass the traffic signal point while the traffic signal is in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed, based on the relative position information and the signal cycle infonnation and that determines a target vehicle speed range which is a recommended range of a travel speed according to the reference target vehicle speed range; and a target vehicle speed display section that displays the target vehicle speed range. The target vehicle speed control section determines the target vehicle speed range if the traffic signal is in the passage allowed indication state and sets the target vehicle speed range to the speed range including zero km/h if the traffic signal is in a passage prohibited indication state where the traffic signal indicates that passage of the vehicle is prohibited.

[0007] Further, the target vehicle speed range is set to a low speed range including zero km/h if the traffic signal is in the passage prohibited indication state.

[0008] A second aspect of the present invention provides a driving support device for supporting driving of a vehicle, the device including: an infrastructure communication section for obtaining signal cycle information concerning switching among indications of a traffic signal from the traffic signal which is disposed in a traveling direction of the vehicle; a position calculation section for calculating relative position information which represents a relative position between a traffic signal point at which the traffic signal is disposed and the vehicle; a target vehicle speed control section for calculating, as a reference target vehicle speed range, a speed range in which the vehicle can pass the traffic signal point, based on the relative position information and the signal cycle information and for determining a target vehicle speed range which is a recommended range of a travel speed according to the reference target vehicle speed range; and a target vehicle speed display section for displaying the target vehicle speed range, in which the target vehicle speed range control section causes the target vehicle speed display section to display the target vehicle speed range if the traffic signal indicates that passage of the vehicle is allowed and prevents the target vehicle speed display section from displaying the target vehicle speed range if the traffic signal indicates that passage of the vehicle is prohibited.

[0009] Further, the traffic signal cycle may be a cycle in which indication of the traffic signal switches or a timing in which the indication of the traffic signal changes.

[0010] Further, the target vehicle speed control section may determine that the traffic signal indicates that passage of the vehicle is allowed if the traffic signal is green.

(0011] Further, the target vehicle speed control section may determine that the traffic signal indicates that passage of the vehicle is allowed if an arrow light apparatus of the traffic signal indicating a direction in which the vehicle is to proceed is illuminated.

[0012] The driving support device may further include a vehicle speed sensor that detects the travel speed of the vehicle. In the driving support device, the target vehicle speed control section may set an indication upper limit speed which is an upper limit value of the target speed range according to a present vehicle speed detected by the vehicle speed sensor and may sets the target vehicle speed range to the speed range including zero km/h if an entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0013] The driving support device may further include a vehicle speed sensor that detects the travel speed of the vehicle. In the driving support device, the target vehicle speed control section may set an indication upper limit speed which is an upper limit value of the target speed range according to a present vehicle speed detected by the vehicle speed sensor and may prevents the target vehicle speed display section from displaying the target vehicle speed range if an entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0014] The driving support device may further include an information obtainment section that obtains a speed limit of a road on which the vehicle is traveling. In the driving support device, the speed limit obtained by the information obtainment section may be set as the indication upper limit speed and the target vehicle speed range may be set to the speed range including zero km/h if the entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0015] The driving support device may further include an information obtainment section that obtains a speed limit of a road on which the vehicle is traveling. In the driving support device, the speed limit obtained by the information obtainment section may be set as the indication upper limit speed and the target vehicle speed display section may be prevented from displaying the target vehicle speed range if the entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0016] Further, the target vehicle speed control section may set the target vehicle speed range to a speed range being equal to or lower than the indication upper limit speed.

[0017] A third aspect of the present invention provides a driving support method for supporting driving of a vehicle, the method including: obtaining signal cycle information concerning switching between indications of a traffic signal from the traffic signal which is disposed in a traveling direction of the vehicle; calculating, as a reference target vehicle speed range, a speed range in which the vehicle can pass the traffic signal point while the traffic signal is in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed based on the relative position information and the signal cycle information; and determining a target vehicle speed range which is a recommended range of a travel speed according to the reference target vehicle speed range; determines the target vehicle speed range if the traffic signal is in the passage allowed indication state and setting the target vehicle speed range to the speed range including zero km/h if the traffic signal is in a passage prohibited indication state where the traffic signal indicates that passage of the vehicle is prohibited.

[0018] A fourth aspect of the present invention provides a driving support method for supporting driving of a vehicle, the method including: obtaining signal cycle information concerning switching between indications of a traffic signal from the traffic signal which is disposed in a traveling direction of the vehicle; calculating relative position information which represents a relative position between a traffic signal point at which the traffic signal is disposed and the vehicle; calculating as a reference target vehicle speed range a speed range in which the vehicle can pass the traffic signal point according to the relative position information and the signal cycle information; and determining a target vehicle speed range which is a recommended range of a travel speed according to the reference target vehicle speed range. The target vehicle speed range is displayed by a target vehicle speed display section if the traffic signal indicates that passage of the vehicle is allowed and the target vehicle speed range is prevented from displaying by the target vehicle speed display section if the traffic signal indicates that passage of the vehicle is prohibited.

[0019J The driving support device in accordance with the present invention can reduce awkwardness experienced by a driver and can appropriately support driving.

BRIEF DESCRIPTION OF THE DRAWINGS [0020] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: FIG. I is an explanatory view illustrating an , example of a driving support system in accordance with the embodiment;

FIG. 2 is a block diagram illustrating a schematic configuration of a vehicle in which the driving support device in accordance with the embodiment is installed;

FIG. 3 is a schematic diagram illustrating an example of a speed indication area of a display device;

FIG. 4 is a flowchart i l lustrating an example of a process of the driving support device; FIG. 5 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 6 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 7 is a flowchart illustrating another example of the process of the driving support device; and

FIG. 8 is a schematic diagram illustrating another example of the speed indication area of the display device.

DETAILED DESCRIPTION OF EMBODIMENTS

[0021 ] A driving support device in accordance with an embodiment of the present invention will be described hereinafter in detail with reference to drawings. It should be understood that this embodiment does not limit the present invention.

[0022] The embodiment will be described with reference to FIGs. 1 to 6. This embodiment relates to a driving support system having a vehicle in which a driving support device is installed. First, a configuration of the driving support system having the vehicle in which the driving support device is installed will be described with reference to FIGs. 1 to 3. FIG. 1 is an explanatory view illustrating an example of the driving support system in accordance with this embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of the vehicle in which the driving support device in accordance with the embodiment is installed. FIG. 3 is a schematic diagram illustrating an example of a speed indication area of a display device.

[0023] The driving support system 1 shown in FIG. 1 has a plurality of vehicles 1 0, a plurality of traffic signals 12, 12a, a plurality of infrastructure information sending devices 14, and a GPS satellite 16. The driving support system 1 is a system that supports driving of a driver on the basis of information that the plurality of vehicles 10 in which a driving support system 19 which will be described later is installed detect the relationships with the other vehicles 10, access the infrastructure information sending device 14 and the GPS satellite 16, and thereby obtain.

[0024] The vehicle 10 is a vehicle which can travel on a road such as an automobile or a truck. The vehicle 10 can travel on a road on which the traffic signals 12, 12a are disposed. A configuration of the vehicle 10 will be described later.

[0025| The traffic signals 12. 12a are lighting devices disposed at intersections. The traffic signal 12 includes lighting sections of three colors that are green, yellow, and red. Further, the traffic signal 12a includes lighting sections (arrow light apparatus) that display arrows in addition to the lighting sections of three colors that are green, yellow, and red. The traffic signals 12. 12a may be disposed in each traveling direction of the vehicle which travels on the road. The traffic signal 12 switches the lighting sections of the three colors that are green, yellow, and red to be illuminated and indicates the state where the vehicle 10 is allowed to pass the intersection in its traveling direction on the road or the state where the vehicle 10 is prohibited from passing, in other words, the vehicle 10 should stop. FIG. 1 illustrates the driving support system 1 in which the traffic signals 12, 12a are disposed at the intersections. However, the positions to dispose the traffic signals 12, 12a are not limited to intersections. For example, the traffic signals 12, 12a may be disposed at pedestrian crossings.

[0026] The infrastructure information sending device 14 sends infrastructure information such as road information of the road on which the vehicles 10 travels and traffic signal information about the traffic signals 12, 12a provided ahead in the traveling direction of the vehicle 10. The infrastructure information sending device 14 of this embodiment is disposed at each intersection and sends the infrastructure information to the vehicles 10 traveling in a certain range around the infrastructure information sending device 14 by wireless communication. Here, the road information typically includes information such as speed limits of the road on which the vehicle 10 travels and the positions of stop lines at intersections. The traffic signal information typically includes traffic signal cycle information such as illumination cycles the illuminated lighting section of the traffic signals 12, 12a change among green, yellow, and red or the timings in which the indications of the traffic signals change. The infrastructure information sending device 14 may be provided at each of the traffic signals 12, 12a. Alternatively, the single infrastructure information sending device 14 may be provided for a plurality of intersections.

[0027] The GPS satellite 16 is a satellite that outputs GPS signals required for positional detection by GPS (GPS: Global Positioning System). Although FIG. 1 shows the driving support system 1 having the single GPS satellite 16, the driving support system 1 has at least the three GPS satellites 16. A device that detects a position by GPS receives GPS signals output from at least three GPS satellites 16, compares the received GPS signals, and thereby detects the position of the own device.

[0028] Next, the vehicle 10 in which the driving support device 19 is installed will be described with reference to FIG. 2. In the driving support system 1 shown in FIG. 1 , all the vehicles are the vehicles 10 in which the driving support system 19 is installed. However, it is sufficient that at least one of the vehicles 10 has the driving support system 19 installed therein. In other words, in the driving support system 1 , vehicles that has no driving support device 19 may travel ahead or behind the vehicle 10 in which the driving support device 19 is installed.

[0029] The vehicle 10 has an ECU 20, a memory section 22, an accelerator actuator 24, a brake actuator 26, an automotive navigation system 28, a speaker 30, a GPS communication section 32, an onboard camera 34, a millimeter-wave radar 36, a infrastructure communication section 38, a vehicle speed sensor 40, a display device 42, an ACC switch 44, and a PCS switch 46. The ECU 20, the memory section 22. the accelerator actuator 24, the brake actuator 26, the automotive navigation system 28, the speaker 30. the GPS communication section 32. the onboard camera 34. the millimeter-wave radar 36, the infrastructure communication section 38. the vehicle speed sensor 40. the display device 42, the ACC switch 44, and the PCS switch 46 of the vehicle 10 also serve as the driving support device 19 of the vehicle 10. Further, the vehicle 10 includes parts that a vehicle in general includes such as a vehicle body, a drive source, a brake system, and operation sections ( for example, a steering wheel, an accelerator pedal, and a brake pedal ), other than the parts described above.

[0030] The ECU 20 is an electronic control unit and controls the parts of the vehicle 10 such as the accelerator actuator 24. the brake actuator 26, the automotive navigation system 28, the speaker 30. the GPS communication section 32, the onboard camera 34, the millimeter-wave radar 36, the infrastructure communication section 38, the vehicle speed sensor 40 and the display device 42. The ECU 20 controls operation of each of the parts on the basis of information obtained by the GPS communication section 32, the onboard camera 34, the millimeter-wave radar 36, the infrastructure communication section 38, and the vehicle sensor 40 and operations by the driver or the like that are input from operation sections such as the ACC switch 44, the PCC switch 46, and the accelerator pedal and the brake pedal that are not shown. Further, the ECU 20 has a vehicle interval control section 20a, a vehicle maintenance control section 20b, and a target vehicle speed control section 20c! The vehicle interval control section 20a, the vehicle maintenance control section 20b, and the target vehicle speed control section 20c will all be described later.

[0031 ] The memory section 22 is a storage device such as a memory and stores conditions and data required for various processes by the ECU 20 and various programs that are executed by the ECU 20. Further, the memory section 22 stores a map information database 22a. The map information database 22a stores information required for travel of the vehicle (such as maps, straight roads, curved roads, upward and downward slopes, highways, sags, and tunnels). Further, the map information database 22a includes a map data file, an intersection data file, a node data file, and a road data file. The ECU 20 accesses the map information database 22a to read out required information.

[0032] The accelerator actuator 24 controls outputs of power sources of the vehicle 10 such as an engine and a motor. For example, the accelerator actuator 24 is capable of controlling an intake amount into the engine, an intake timing, an ignition timing, a frequency and a voltage value provided by the motor, and the like. The accelerator actuator 24 is electrically connected to the ECU 20. The operation of the accelerator actuator 24 is controlled by the ECU 20. For example, the ECU 20 actuates the accelerator actuator 24 in response to accelerator control signals and thereby adjusts the intake amount into the engine, the intake timing, the ignition timing, the frequency and the voltage value provided by the motor. In other words, the accelerator actuator 24 is a device for automatically controlling the driving force provided by the power sources and receives the accelerator control signals output from the ECU 20 and drives each section, thereby controlling driving conditions and generating desired driving force. As described above, the accelerator actuator 24 controls the driving force applied to the vehicle 10 and thereby adjusts its acceleration.

[0033J The brake actuator 26 controls operation of the brake device installed in the vehicle 10. For example, the brake actuator 26 controls the hydraulic pressure of a wheel cylinder provided in the brake device. The brake actuator 26 is electrically connected to the ECU 20. The operation of the brake actuator 26 is controlled by the ECU 20. The ECU 20 actuates the brake actuator 26 in response to brake control signals and thereby adjusts the brake hydraulic pressure of the wheel cylinder. In other words, the brake actuator 26 is a device for automatically controlling the braking force applied by the brake and receives the brake control signals output from the ECU 20 and operates a solenoid and a motor of a mechanism that supplies a hydraulic fluid to the wheel cylinder, thereby controlling the brake hydraulic pressure and generating desired braking force. As described above, the brake actuator 26 controls the braking force applied to the vehicle 10 and thereby adjusts its deceleration.

|0034] The automotive navigation system 28 is a device for guiding the vehicle 10 to a prescribed destination. The automotive navigation system 28 is capable of two-way communication with the ECU 20. The automotive navigation system 28 includes a display section and causes the display section to display map information around the vehicle on the basis of infomiation stored in the map information database 22a and the infomiation about a present position that is obtained by the GPS communication section 32 which will be described later. Further, the automotive navigation system 28 detects a route to the destination by use of information stored in the map infomiation database 22a, the information about the present position that is obtained by the GPS communication section 32 which will be described later, and the destination information input by the driver or the like and causes the display section to display the detected route information. The automotive navigation system 28 may include a map information database and a GPS communication section in the own system separately from the map infomiation database 22a and the GPS communication section 32 and may thereby provide route guidance and the information about the present position.

[0035] The speaker 30 outputs sounds in the vehicle 10. The speaker 30 outputs sounds corresponding to sound signals sent by the ECU 20.

[0036] The GPS communication section 32 receives the respective GPS signals output from the plurality of GPS satellites 16. The GPS communication section 32 sends the received GPS signals to ECU 20. The ECU 20 analyzes the plurality of received GPS signals and thereby detects positional information of the own unit.

[0037] The onboard camera 34 is an image capturing device that is disposed in a front portion of the vehicle 10 and obtains images ahead (ahead in the traveling direction) of the vehicle 10. The onboard camera 34 sends the obtained images ahead of the vehicle 10 to the ECU 20. The ECU 20 analyzes the images obtained by the onboard camera 34 and thereby can obtain information about the state of the area ahead of the vehicle 10, in other words, whether the vehicle has the other vehicle 10 ahead, the vehicle 10 is close to the traffic signals 12, 12a, the vehicle 10 is close to an intersection, and the like.

[0038] The millimeter-wave radar 36 is a sensor to measure the vehicle interval between the own vehicle and the other vehicle ahead (the vehicle ahead of the vehicle 10). The millimeter-wave radar 36 emits electric waves of millimeter-wave band forward of the vehicle 10 and receives the electric waves that have reflected on an object (the vehicle ahead) and returned to the own radar among the emitted electric waves. The millimeter-wave radar 36 compares the output conditions of the emitted electric waves and the detection results of the received electric waves and thereby calculates the interval to the vehicle ahead. Further, the millimeter-wave radar 36 may detect the distance to an obstacle ahead of the own vehicle. The millimeter-wave radar 36 sends the information about the calculated interval to the vehicle ahead to the ECU 20. In this embodiment, the millimeter-wave radar 36 is used as the sensor for measuring the vehicle interval between the own vehicle to the vehicle ahead (the vehicle ahead of the vehicle 10). However, various kinds of sensors that can measure the distance between the vehicle 10 and an object ahead of the vehicle 10 may be used. For example, the vehicle 10 and the driving support device 19 may employ a laser radar sensor instead of the millimeter-wave radar 36.

[0039] The infrastructure communication section 38 performs wireless communication with the infrastructure information sending device 14 described above. The infrastructure communication section 38 obtains the infrastructure information sent by the infrastructure information sending device 14 and sends the obtained infrastructure information to the ECU 20. The infrastructure communication section 38 constantly communicates with the infrastructure infonnation sending devices 14 which are capable of communication and may thereby obtain the infrastructure infonnation. communicates with the infrastructure infonnation sending devices 14 at certain time intervals and may thereby obtains the infrastructure infonnation. or when the new infrastructure information sending device 14 becomes capable of communication, communicates with this infrastructure information sending device 14 and may thereby obtain the infrastructure infonnation.

[0040] The vehicle speed sensor 40 detects the vehicle speed of the vehicle 10. The vehicle speed sensor 40 sends the infonnation about the obtained vehicle speed to the ECU 20.

[0041 ] The display device 42 is a display device that displays various kinds of infomiation to be informed to the driver, and is an instrument panel disposed on a dash board of the vehicle 10, for example. The display device 42 may be a l iquid crystal display device or may be a display device having various measuring instruments disposed therein. The display device 42 displays information such as a remaining fuel amount, output of the drive source (engine speed), open or close states of doors, and states of use of seatbelts. The display device 42 includes a speed indication area 48 which indicates the vehicle speed.

[0042] As shown in FIG. 3. the speed indication area 48 has a scale display section 50, and a needle 52. The scale display section 50 has an arc shape and has a scale between zero km/h and 160 km/h. The needle 52 points the vehicle speed as a measurement result and points 40 km/h in FIG. 3. The speed indication area 48 is an analog meter. The position on the scale display section 50 which the needle 52 points changes in response to the present vehicle speed. Accordingly, the driver checks the position of the needle 52 on the speed indication area 48 and can thereby notice the result of the detection of the present vehicle speed.

[0043] The ACC ( Adaptive Cruise Control) switch (ACC control switch) 44 is used by the driver to conduct various operation for ACC control. The driver can turn ON or OFF the ACC control, inputs a set vehicle speed, inputs a prescribed interval in vehicle-following traveling, and the like by the ACC switch 44. The ACC switch 44 sends the operation input by the driver to the ECU 20 as operation signals. The vehicle interval control section 20a of the ECU 20 executes various control on the basis of the operation signals sent from the ACC switch 44.

[0044] The PCS (Pre-Crash Safety or Pre-collision System) switch (PCS control switch) 46 is used by the driver to conduct various operation for PCS control. The driver can turn ON or OFF the PCS control, inputs a detection target distance, sets a safety level, and the like by the PCS switch 46. The PCS switch 46 sends the operation input by the driver to the ECU 20 as operation signals. The vehicle maintenance control section 20b of the ECU 20 executes various control on the basis of the operation signals sent from the PCS switch 46.

[0045] Next, the control executed by the vehicle interval control section 20a and the vehicle maintenance control section 20b, and the target vehicle speed control section 20c of the ECU 20 will be described. The vehicle interval control section 20a executes the ACC (Adaptive Cruise Control ) control. The vehicle interval control section 20a executes vehicle-following control in which the vehicle ahead is detected by the onboard camera 34 and the millimeter-wave radar 36 and the own vehicle travels to follow the vehicle ahead while sustaining a certain vehicle interval therefrom and constant speed travel control in which the vehicle 10 is caused to travel such that the vehicle speed of the vehicle 10 is sustained at a constant speed.

[0046] The vehicle maintenance control section 20b executes the PCS (Pre-Crash Safety or Pre-Collision System) control. Specifically, the vehicle maintenance control section 20b performs various processes (warning to the driver, brake assist operation, or the like) for protection against a collision by detecting obstacles by the onboard camera 34 and the millimeter radar 36. Further, the vehicle maintenance control section 20b may operate a passenger protection device which is capable of protecting the passengers in the vehicle 10 as one of the various processes for protection against a collision. Actuators serving as the passenger protection device are such as an actuator used for the brake assist for assisting braking force in response to braking operation of the driver and a winding motor for winding up the seatbelt.

[0047] Next, the target vehicle speed control section 20c will be described. The target vehicle speed control section 20c calculates a reference target vehicle speed range on the basis of information obtained by each section of the vehicle 10, modifies the calculated reference target vehicle speed range calculated on the basis of a preset conditions and thereby determines a target vehicle speed range (target speed range), and causes the speed indication area 48 of the display device 42 to indicate the determined target vehicle speed range. Specifically, the target vehicle speed control section 20c calculates the speed range (reference target vehicle speed range), which is the travel speed range which is required for passage the traffic signals 12. 12a while they are in the green light state (in other words, the traffic signals are in a passage allowed indication state), on the basis of ( 1 ) the traffic signal cycle information obtained by the infrastructure communication section 38 about switching among the indications of the traffic signals such as the illumination cycle in which the indications the traffic signals 1 2, 12a disposed at the intersections and the pedestrian crossings to be passed through switch and the timings at which the indication of the traffic signals changes; (2) and information such as relative positions which are the distances between the vehicle 10 and the traffic signals 12, 12a (accurately, the distances to the intersection or the pedestrian crossings (also referred to as "object to be passed through" and "traffic signal point ^" ) at which the traffic signals 12, 12a are disposed). Further, the target vehicle speed control section 20c calculates and determines the target vehicle speed range on the basis of the present states of the traffic signals disposed at the intersection, the pedestrian crossings, or the like as the object to be passed through (in other words, the traffic signal point). The speed indication area 48 is caused to indicate the calculated target vehicle speed range (recommended travel speed range). Further, the target vehicle speed control section 20c calculates and determines the target vehicle speed range on the basis of the comparison result between the calculated reference target vehicle speed range and the present vehicle speed in addition to the present states of the traffic signals disposed at the intersection and pedestrian crossings as the object to be passed through and causes the speed indication area 48 to indicate the calculated target vehicle speed range (recommended vehicle speed range). As described above, the target vehicle speed control section 20c perfonns green wave support which is control for advising the driver of the vehicle speed in order to reduce the frequency in which the vehicle 10 stops at the red lights. The passage allowed indication state of the traffic signal is a state where the traffic signal provides the indication that passage of the object route is allowed. However, such an indication is not limited to the green light indication, but includes the indication of the arrow light apparatus. The green light indication is the state where, for example, the blue, green, or another color which indicates that the vehicle is allowed to pass is illuminated among the illuminated sections of the traffic signal. Further, the yellow light indication may be set as the passage allowed indication state of the traffic signal.

[0048] The control executed by the target vehicle speed control section 20c of the ECU 20 of the vehicle 10 will be described hereinafter more in detail with reference to FIGs. 4 to 6. FIG. 4 is a flowchart illustrating an example of a process of the driving support device. FIGs. 5 and 6 are each a schematic diagram illustrating an example of the speed indication area of the display device.

[0049] The target vehicle speed control section 20c of the ECU 20 determines whether the green wave support is possible in step S I 2. Specifically, the target vehicle speed control section 20c determines whether the information required for calculating the target vehicle speed range has been obtained and the conditions of allowing display of the target vehicle speed range are satisfied. Examples of the information required for calculating the target vehicle speed are the infrastructure information described above such as the illumination cycles of the traffic signals 12, 1 2a and the timings of change in the traffic signals at the objects to be passed through, the information about the present position required for calculating the distances between the vehicle 10 and the traffic signals 12, 1 2a, the map _. information containing the positional information of the traffic signals 12, 12a. Further, examples of the conditions of allowing display of the target vehicle speed range are the distances (distances to the object intersections) between the vehicle 10 and the traffic signals 12, 12a being a certain distance or longer, the present vehicle speed of the vehicle 10 being a certain speed or higher, and the like. If the distance (distance to the object intersection or the like) between the vehicle 10 and the traffic signals 12, 12a is shorter than the certain distance, the target vehicle speed control section 20c determines that it does not perform the green wave support since if the target vehicle speed range is indicated, it is difficult for the driver to drive in response to the indication. Further, if the present vehicle speed of the vehicle 10 is lower than the certain speed, the target vehicle speed control section 20c determines that it does not perform the green wave support since there is high possibility that a traffic jam has occurred on the road on which the vehicle is traveling and the travel speed may be limited, or the traffic may have been stopping or may have stopped for some reasons, and if the target vehicle speed range is indicated, it is difficult for the driver to drive in response to the indication. If the target speed control section 20c determines that the support is not possible (No) in step S I 2, in other words, the support cannot be performed, the process is terminated.

[0050] Further, if the target vehicle speed control section 20c determines that the support is possible (Yes) in step S 12, the target vehicle speed control section 20c conducts a passage or stop detennination in step S I 4. In other words, in step S I 4, the target vehicle speed control section 20c calculates the reference target vehicle speed range on the basis of the obtained information and determines whether performing a passage support or a stop support according to the calculated reference target vehicle speed range. Here, the reference target vehicle speed range is the vehicle speed range in which the vehicle can pass the object intersection, pedestrian crossing, or the like, in other words, the vehicle speed range in which the vehicle can pass the object intersection, pedestrian crossing, or the like while the object traffic signal is the green light. Further, the target vehicle speed control section 20c of this embodiment determines that it performs the stop support if the lower limit of the calculated reference target vehicle speed range is a speed a higher than the present vehicle speed, in other words, (the present vehicle speed + a) < (the lower limit speed of the reference target vehicle speed range).

[0051 ] The target vehicle speed control section 20c makes a determination in step S I 4. Thereafter, in step S I 6, the target vehicle speed control section 20c determines whether or not the passage support is possible, in other words, the detennination result in step S 14 is the passage support. If the target vehicle speed control section 20c determines that the passage support is not possible (No) in step S I 6, the process progresses to step S22.

[0052] Further, if the target vehicle speed control section 20c detennines that the passage support is possible (Yes) in step S I 6, in other words, the determination result in step S 14 is the passage support, the target vehicle speed control section 20c determines whether the present color of the traffic signal is green in step S I 4. That is, the target vehicle speed control section 20c _. determines whether the green light is illuminated on the traffic signal disposed at the intersection, the pedestrian crossings, or the like as the object to be passed through (in other words, the traffic signal point). The target vehicle speed control section 20c determines whether or not the green light is illuminated on the traffic signal on the basis of the traffic signal cycle obtained by the infrastructure communication section 38. If the target vehicle speed control section 20c determines that the traffic signal is not green (No) in step S I 8, in other words, the traffic signal does not indicate that passage is allowed, in other words, the traffic signal is in a passage prohibited indication period, the process progresses to step S22. The passage prohibited indication period of the traffic signal corresponds to a passage prohibited indication state where the traffic signal indicates that the vehicle is prohibited from passage; for example, a state where the red light is illuminated on the traffic signal. The passage prohibited indication period of the traffic signal may include a state where the yellow light is illuminated on the traffic signal.

[0053] Further, if the target vehicle speed control section 20c determines that the traffic signal is green (Yes) in step S I 8, the target vehicle speed control section 20c executes passage support indication in step S20. As the passage support indication, the target vehicle speed control section 20c determines the target vehicle speed range on the basis of the reference target vehicle speed range and indicates the determined target vehicle speed range in the speed indication area. Here, the target vehicle speed control section 20c preferably adjusts the target vehicle speed range to be indicated in the speed indication area 48 on the basis of the reference target vehicle speed range calculated in step S I 4, the present vehicle speed, and preset conditions. The target vehicle speed control section 20c of this embodiment sets the upper limit (indication upper limit speed) of the target vehicle speed range to a speed of the present speed + a or lower.

[0054] For example, the target vehicle speed control section 20c displays a speed indication area 48a shown in FIG. 5. The speed indication area 48a indicates a marker 60 in the speed range on the . scale display section 50 which overlaps with the target vehicle speed range. Here, in this embodiment, since the target vehicle speed range is from 30 km/h to 50 km/h, the marker 60 is indicated in the speed range of 30 km/h to 50 kni/h. In a case that the speed indication area 48a has the scale display section 50 displayed as an image on a liquid crystal display device, the marker 60 may overlap therewith as an image displayed on the liquid crystal display device. Further, in a case that the speed indication area 48a has the scale display section 50 printed in ink or the like, an illuminated section is disposed in a portion on which the scale is displayed in the scale display section 50, the illuminated section of the target speed range is illuminated, and the marker 60 may thereby be indicated. As described above, the target vehicle speed control section 20c indicates the determined target vehicle speed range by the marker 60 overlapping with the scale display section 50, thereby allowing a user to notice the determined target vehicle speed range. Here, if a part of the reference target vehicle speed range calculated in step S 14 is higher than the present vehicle speed + a, the target vehicle speed control section 20c of this embodiment sets the upper limit value of the target vehicle speed range to the present vehicle speed + a and indicate no speed higher than the present vehicle speed + a. The target vehicle speed control section 20c performs the process shown in step S20 and thereafter progresses to step S24.

[0055] If the target vehicle speed control section 20c determines that the passage support is not possible (No) in step S I 6, or if determining that the color of the traffic signal is not green (No) in step S I 8, the target vehicle speed control section 20c executes stop support indication in step S22. Here, in the stop support indication, a speed range around zero km/h is indicated as the target vehicle speed range. For example, the target vehicle speed control section 20c displays a speed indication area 48b shown in FIG. 6. The speed indication area 48b indicates a marker 62 in the speed range on the scale display section 50 which overlaps with the target vehicle speed. Here, in the stop support indication, since the target vehicle speed range is a speed range around zero km/h (a low speed range including zero km/h, zero km/h to 10 km/h in this embodiment), the speed indication area 48b indicates the marker 62 in a speed range around zero km/h. As described above, the target vehicle speed control section 20c indicates the determined target vehicle speed range by the marker 62 overlapping with the scale display section 50, thereby allowing the user to notice the determined target vehicle speed range. Accordingly, in step S22. the user can be noticed that stopping the vehicle is recommended. The target vehicle speed control section 20c performs the process shown in step S22 and thereafter progresses to step S24.

[0056] The target vehicle speed control section 20c perfomis the process of step S20 or step S22 and thereafter determines whether indication terminating conditions are satisfied in step S24. Here, the indication terminating conditions are conditions for terminating the indication of the preset target vehicle speed range. Example of those may include cases that the distance between the vehicle and the intersection (the object traffic signal) becomes a predetermined distance or shorter, that the vehicle speed falls out a predetermined range, that a predetermined time period has passed after the target vehicle speed range was indicated. If the target vehicle speed control section 20c detennines that the conditions are not satisfied (No) in step S24, the process progresses to step S I 4. and the processes described above are repeated. In other words, the target vehicle speed range is recalculated and again indicated. If the target speed control section 20c determines that the conditions are satisfied (Yes) in step S24, the process is terminated.

[0057J The driving support device 19 (and the vehicle 10 having that, the driving support system 1 ) switches the indication between the passage support indication and the stop support indication on the basis of the illuminated state of the traffic signal. Specifically, the driving support device 19 performs the passage support indication if the traffic signal as the object to be passes through or performs the stop support indication if the traffic signal is not the green light. This allows reduction in the possibility that the indicated target vehicle speed range causes the driver to experience awkwardness. In other words, the driving support device 19 can prevent the indication of the target vehicle speed range that advises the driver to sustain the speed or accelerate the vehicle in the case that the driver is required to decelerate the vehicle such as a case that the traffic signal in front of the vehicle is the red, thereby reducing in the possibility that the driver experiences awkwardness.

|0058] Further, the driving support device 19 of this embodiment determines whether the passage support is possible, specifically, whether or not the calculated reference target vehicle speed range exceeds the upper limit value set on the basis of the present vehicle speed. If the calculated reference target vehicle speed range exceeds the upper limit value set on the basis of the present vehicle speed, the driving support device 19 executes the stop support indication and can thereby prevent the reference target vehicle speed range that requires rapid acceleration for passage the object intersection or pedestrian crossing from being indicated as the target vehicle speed range. This allows prevention of the indication of the target vehicle speed range that requires rapid acceleration and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress. Further, since this allows the driver to travel at the target vehicle speed range by acceleration and deceleration to an appropriate extent, the driver can sustain a comfortable driving state and allow the vehicle to travel in preferable conditions (in this embodiment, while reducing stops at the red lights).

[00591 Further, if the calculated reference target vehicle speed range exceeds the upper limit value set on the basis of the present vehicle speed, the driving support device 19 sets the part of the reference target speed range which is not higher than the upper limit value as the target speed range. Accordingly, the target vehicle speed range which is not higher than the upper limit value set on the basis of the present vehicle speed is indicated in the speed indication area 48. In other words, the driving support device 19 can prevent the indication of the speed higher than the upper limit value (indication upper limit speed) set on the basis of the present vehicle speed as the target vehicle speed range to be indicated in the speed indication area 48. Accordingly, the driving support device 19 can prevent the indication of the target vehicle speed range that requires rapid acceleration and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress. Further, since this allows the driver to travel at the target vehicle speed range by acceleration and deceleration to an appropriate extent, the driver can sustain a comfortable driving state and allow the vehicle to travel in preferable conditions (in this embodiment, while reducing stops at the red lights).

[0060] Further, the driving support device 19 sets the present vehicle speed + cx, in other words, a speed a certain magnitude higher than the present vehicle speed as the reference speed for the determination whether the passage support is possible, thereby allowing prevention of the acceleration required for gaining the target vehicle speed range from becoming large. This allows the vehicle 10 and the driving support device 19 to indicate the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0061] Further, if the passage support is not possible, specifically, if the reference target vehicle speed range is higher than the indication upper limit speed, in other words, if the entire reference target speed range exceeds the indication upper limit speed, the driving support device 1 9 indicates the target vehicle speed range for the stop support, thereby recommending that the driver should stop the vehicle. This allows the driving support device 19 to prevent recommendation of difficult acceleration to the driver but to provide recommendation of stopping to the driver, thereby allowing reduction in the possibility of causing the driver to experience awkwardness or stress.

[0062] In this embodiment, if the passage support is not possible, specifically, if the reference target vehicle speed range is higher than the indication upper limit speed or the traffic signal is not the green light, the target vehicle speed range for the stop support is indicated. However, the present invention is not limited to this. If the passage support is not possible or the traffic signal is not the green light, the driving support device 19 may prevent indication of the target vehicle speed instead of the process of step S22.

[0063] The driving support device 19 of this embodiment sets the indication upper limit speed (the reference speed for the determination whether the passage support is possible) to the present vehicle speed + a, in other words, to the speed a certain magnitude higher than the present vehicle speed. However, the present invention is not limited to this. Here, the driving support device 19 may set the indication upper limit speed to the present vehicle speed + G x t. Here. "G" denotes acceleration, and " ^' denotes time. In other words, the driving support device 19 may set the reference speed for the determination whether the passage support is possible to the present speed + G x t, in other words, the speed which can be achieved by acceleration G in t second(s). Here, the t second(s) may be a value which changes on the basis of the distance to the traffic signal and the present vehicle speed. For example, when the distance to the traffic signal is long, t may be made large. When the distance to the traffic signal is short, t may be made small.

[0064] Further, the driving support device 19 of this embodiment may set the indication upper limit speed to the present vehicle speed. As described above, the target vehicle speed control section 20c the reference speed for the determination whether the passage support is possible to the present vehicle speed and can thereby set the target vehicle speed range as a speed which requires no acceleration. Accordingly, the driving support device 19 can prevent the indication of the target vehicle speed range which requires acceleration and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0065] Further, each example of the driving support device 1 9 of the embodiment described above uses the present vehicle speed to determine the indication upper limit speed. However, the present invention is not limited to this. The driving support device 19 may use the speed limit of the road (way) on which the vehicle is traveling. Here, the speed limit is, for example, the legal speed limit of the road on which the vehicle is traveling at present and may be obtained from the infrastructure information obtained by the infrastructure communication section 38 or may be obtained from the information about the present position stored in the map information database 22a by detecting the present position by use of the GPS signals received by the GPS communication section 32. The driving support device 19 may use a combination of the infrastructure communication section 38, the GPS communication section 32, and the map information database 22a as an infoimation obtainment section for obtaining the information about the speed limit. The information obtainment section for obtaining the information about the speed limit may use other functions of the driving support device 19. for example, the onboard camera 34. The driving support device 19 uses the onboard camera 34 to obtain images of traffic signs provided on the road on which the vehicle is traveling and may thereby detect the legal speed limit displayed in the image of the traffic sign as the speed limit. The driving support device 19 uses the speed limit as the reference speed for the detennination whether the passage support is possible and can thereby prevent the indication of the target vehicle speed range from exceeding the speed limit. Accordingly, the driving support device 19 can indicate the target vehicle speed range as a speed of the speed limit or lower, can thereby prevent the indication of the speeds at which the vehicles must not travel, and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0066] The driving support device 19 preferably uses both the present vehicle speed and the speed limit to determine the indication upper limit speed (the reference speed for the determination whether the passage support is possible). In other words, in each case, the driving support device 19 preferably use the present vehicle speed to determine the indication upper limit speed so that the target vehicle speed range does not exceed the speed limit. Accordingly, the driving support device 19 can provide both the effects described above and thereby allows the indication of the target vehicle speed range with further less possibility of causing the driver to experience awkwardness or stress.

[0067] Further, an example is described where the driving support device 19 of the embodiment described above sets the indication upper limit speed as the reference speed for the determination whether the passage support is possible and one of various conditions. However, the reference speed for the determination whether the passage support is possible may be set separately from the indication upper limit speed. In other words, the driving support device 19 may determine whether it executes the passage support according to the reference speed for the determination whether the passage support is possible and may determine the upper limit value to be indicated as the target vehicle speed range on the basis of an indication upper limit speed other than the reference speed for the determination whether the passage support is possible. Further, similarly to the reference speed for the determination whether the passage support is possible, the various conditions described above can be used for the indication upper limit speed. In such a case, the driving support device 19 adjusts the reference target vehicle speed range on the basis of the indication upper limit speed and determines the target vehicle speed range.

[0068] The driving support device 19 preferably provides the indicated markers having different colors according to the target vehicle speed range which is indicated in the passage support or the target vehicle speed range which is indicated in the stop support. The indication may have different patterns, illumination states, or the like instead of colors. This allows the driver to understand that the indication is to notify the passage support or the stop support.

[0069] Next, another example of the process of the driving support system will be described with reference to FIG. 7. Here, FIG. 7 is a flowchart illustrating another example of the process of the driving support device. The process steps shown in FIG. 7 which are the same as the steps shown in FIG. 4 will be denoted by like step numerals and specific descriptions will be omitted.

[0070] The target vehicle speed control section 20c of the ECU 20 determines whether the green wave support is possible in step S I 2. If the target speed control section 20c determines that the support is not possible (No) in step S I 2. in other words, the support cannot be performed, the process is terminated. Further, if the target vehicle speed control section 20c determines that the support is possible (Yes) in step S I 2, the target vehicle speed control section 20c conducts a passage or stop determination in step S 14.

[0071] The target vehicle speed control section 20c makes a determination in step S I 4. Thereafter, in step S I 6, the target vehicle speed control section 20c determines whether or not the passage support is possible, in other words, the deteiTnination result in step S 14 is the passage support. If the target vehicle speed control section 20c determines that the passage support is not possible (No) in step S I 6, the process progresses to step S22.

[0072] Further, if the target vehicle speed control section 20c deten ines that the passage support is possible (Yes) in step S I 6, in other words, the determination result in step S 14 is the passage support, the target vehicle speed control section 20c determines whether the present color of the traffic signal is green in step S I 8. If the target vehicle speed control section 20c detennines that the color of the traffic signal is green (Yes) in step S I 8. the process progresses to step S20.

[0073] Further, if the target vehicle speed control section 20c determines that the color of the traffic signal is not green (No) in step S I 8, the target vehicle speed control section 20c detennines whether the arrow light apparatus is illuminated in step S20. Specifically, the target vehicle speed control section 20c determines whether the arrow- light apparatus of the object traffic signal indicates the direction to proceed. The target vehicle speed control section 20c can determine whether the a trow light apparatus is illuminated by use of the infrastructure infonnation. If the target vehicle speed control section 20c determines that the arrow light apparatus is illuminated (Yes) in step S30, in other words, the arrow light apparatus indicating the direction to proceed (the direction in which the vehicle passes through) is i lluminated, the target vehicle speed control section 20c determines the traffic signal indicates that passage is allowed, and the process progresses to step S20. If the target vehicle speed control section 20c determines that the aiTow light apparatus is not illuminated (No) in step S30. in other words, the arrow light apparatus indicating the direction to proceed is not illuminated, the target vehicle speed control section 20c detennines the traffic signal does not indicate that passage is allowed, and the process progresses to step S22. Further, the target vehicle speed control section 20c always detennines that no arrow light apparatus is illuminated when the object traffic signal has no arrow light apparatus.

[0074] Further, if the target vehicle speed control section 20c detennines that the traffic signal is green (Yes) in step S I 8, or if determining that the arrow light apparatus is illuminated (Yes) in step S30, the target vehicle speed control section 20c executes the passing-though support indication in step S20. The target vehicle speed control section 20c performs the process shown in step S20 and thereafter progresses to step S24.

[0075J If the target vehicle speed control section 20c determines that the passage support is not possible (No) in step S I 6. or if detennining that the arrow light apparatus is not illuminated (No), the target vehicle speed control section 20c executes the stop support indication in step S22. The target vehicle speed control section 20c performs the process shown in step S22 and thereafter progresses to step S24. The target vehicle speed control section 20c performs the process of step S20 or step S22 and thereafter determines whether indication terminating conditions are satisfied in step S24. If the target vehicle speed control section 20c determines that the conditions are not satisfied (No) in step S24, the process progresses to step S I 4, and the processes described above are repeated. In other words, the target vehicle speed range is recalculated and again indicated. If the target speed control section 20c determines that the conditions are satisfied (Yes) in step S24, the process is terminated.

[0076] As shown in FIG. 7, the driving support device 19 determines the indication state of the traffic signal on the basis of the illumination states of the green light and the arrow light apparatus. Accordingly, the driving support device 19 can determine whether or not the traffic signal indicates that passage the intersection or pedestrian crossing at which the traffic signal is disposed is allowed. This allows the driving support device 19 to provide indication of the target vehicle speed range from which the driver experiences further less awkwardness.

[0077] Further, if the green light is indicated (illuminated) or if the arrow light apparatus is illuminated, the driving support device 19 of the embodiment described above determines that the traffic signal indicates that passage is allowed and executes the passage support indication. Otherwise, the driving support device 19 determines that the traffic signal does not indicate that passage is allowed and executes the stop support indication. However, the present invention is not limited to this. The driving support device 1 9 may determine whether or not the indication state of the traffic signal matches the indication that passage is allowed or whether or not the indication state matches the indication that stopping is recommended. If the red light is indicated (illuminated), the driving support device 19 determines that the traffic signal does not indicate that passage is allowed. Otherwise, for example, if the green or yellow light is indicated (illuminated), the driving support device 19 may execute the passage support indication.

[0078] Further, when the traveling route is set by the automotive navigation system 28, the driving support device 19 calculates the traveling direction and a route to pass on the basis of the traveling route set by the automotive navigation system 28 and preferably executes the processes of steps S 18 and S30 on the basis of whether or not the traffic signal on the route to pass indicates that the passage in the traveling direction is allowed. As described above, the direction to proceed is specified on the basis of the traveling route, thereby make it possible to indicate of the target vehicle speed range appropriate for the indication state of the traffic signal.

[0079] Further, the target vehicle speed control section 20c of the driving support device 19 may use at least one of the onboard camera 34 and the millimeter- wave radar 36 to determine whether or not a vehicle is present within a certain distance ahead. If it is determined that a vehicle is present within the certain distance ahead, the target vehicle speed control section 20c may prevent execution of the stop support or indication of the target vehicle speed range. Accordingly, the possibility can be reduced that since the target vehicle speed range for passage the object intersection or pedestrian crossing in a state where a vehicle is present within the certain distance ahead, the driver is caused to rush.

[0080] Further, in the case that ( upper limit value Vmax ) - ( lower limit value Vmin) < ( threshold value), in other words, the speed difference between the upper limit value and the lower limit value of the determined target vehicle speed range is smaller than the threshold value, the driving support device 19 may prevent indication of the target vehicle speed range. For example, after determining the target vehicle speed range in step S I 8. the target vehicle speed control section 20c determines whether ( upper limit value Vmax) - ( lower limit value Vmin > ( threshold value), in other words, the difference between the upper limit value Vmax and the lower limit value Vmin of the target vehicle speed range is larger than the threshold value. If it is determined that ( upper limit value Vmax ) - ( lower limit value Vmin) > ( threshold value ), the target vehicle speed control section 20c indicates the determined target vehicle speed range in the speed indication area. If the determination is that ( upper limit value Vmax) - ( lower limit value Vmin) > ( threshold value) is false, in other words, if it is determined that ( upper limit value Vmax) - ( lower limit value Vmin) < ( threshold value), the target vehicle speed control section 20c prevent indication of the determined target vehicle speed range.

[0081 ] Further, in the case that ( upper limit value Vmax) - ( lower limit value Vmin) < ( threshold value), in other words, the speed difference between the upper limit value and the lower limit value of the determined target vehicle speed range is smaller than the threshold value, the driving support device 19 prevent indication of the target vehicle speed range and thereby prevent indication of the target vehicle speed range which permits a narrow speed range and results in difficult conditions for speed adjustment. Accordingly, the driving support device 19 can selectively indicates the target vehicle speed range which permits a wide speed range and results in relatively easy condition for speed adjustment and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0082 J Further, the driving support device 19 of the embodiment described above provides the speed indication in the speed indication area 48 of the display device 42 by the analog meter. However, the present invention is not limited to this. Further, the driving support device 1 9 of the embodiment described above provides the speed indication in the speed indication area 48 of the display device 42 by a digital meter. Here, FIG. 8 is a schematic diagram illustrating another example of the speed indication area of the display device. A speed indication area 102 is a indication mechanism which indicates a speed in a number and has a first area 104 and a second area 106. The present vehicle speed is indicated in the first area 104. The first area 104 of FIG. 8 indicates "40 km/h". The second area 106 is an area above the first area 104 on a screen. The target vehicle speed range is indicated in the second area 106. The second area 106 of FIG. 8 indicates "30 km/h ~ 53 km/If'. As described above, the driving support device 19 can obtain a similar effect to the above example by indicating the speed indication area 102 of the display device 42 by the digital meter. Here, the driving support device 19 preferably indicates the present vehicle speed indicated in the first area 104 of the speed indication area 102 and the target vehicle speed range indicated in the second area 106 in at least either different colors or different sizes. Accordingly, the driving support device 1.9 can reduce the possibility that the driver confuses the present vehicle speed with the target vehicle speed range.

[0083] Further, the driving support device 19 of the embodiment described above includes the vehicle interval control section 20a and the vehicle maintenance control section 20b. However, the driving support device 19 does not necessarily have to include the vehicle interval control section 20a and the vehicle maintenance control section 20b. Further, the vehicle 10 and the driving support device 19 may be differently configured as long as the control by the vehicle speed control section 20c described above can be achieved.

[0084) While the disclosure has been explained in conjunction with specific exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, exemplary embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. There are changes that may be made without departing from the scope of the disclosure.