CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to Untied States Provisional Application No. 63/403,010 filed September 1 , 2022.

TECHNICAL FIELD

[0002] This disclosure relates to a camera monitor system (CMS) for use in a commercial truck or similar vehicle, and, in particular, to a CMS having a display brightness control.

BACKGROUND

[0003] Mirror replacement systems, and camera systems for supplementing mirror views, are utilized in commercial vehicles to enhance the ability of a vehicle operator to see a surrounding environment. Camera monitor systems (CMS) utilize one or more cameras to provide an enhanced field of view to a vehicle operator. In some examples, the CMS covers a larger field of view than a conventional mirror, or include views that are not fully obtainable via a conventional mirror.

[0004] In a typical CMS, there is a camera arm arranged on each of the left- and right-hand sides of the vehicle to provide Class II and Class IV views. A display is provided on the A-pi liar on both driver and passenger sides to display the field of view for the camera arm on that side, simulating a conventional mirror.

[0005] To ensure that the displays are visible to the driver in various ambient light conditions, each display includes one or more ambient light sensors, which is used to adjust the brightness of that display based upon that display’s sensor reading. In one example system, each light sensor is used to adjust a backlight level only of its respective, individual display. Such a system may not perform as desired.

SUMMARY

[0006] In one exemplary embodiment, a camera monitor system includes multiple cameras that include first and second cameras that respectively provide first and second fields of view. Multiple displays include first and second displays that are configured to respectively depict at least portions of the first and second fields of view, the first and second displays respectively include a first and second brightness. Multiple ambient light sensors include first and second ambient light sensors that are in proximity respectively to the first and second displays and are configured to respectively provide a first and second light ambient signal indicative of an amount of ambient light respectively in a region of the first and second displays. A controller is in communication with the first and second displays and is in communication with the first and second ambient light sensors. The controller is configured to adjust one of the first and second brightnesses of one of the first and second displays based upon at least the other of the first and second ambient light signals of the other of the first and second displays.

[0007] In a further embodiment of any of the above, the controller is configured to determine which of the first and second ambient light signals corresponds to the one of the first and second displays that have a greater brightness than the other of the first and second displays. The controller is configured to increase a brightness of the other of the first and second displays.

[0008] In a further embodiment of any of the above, the controller is configured to increase the brightness of the other of the first and second displays by about half the difference between the first and second brightnesses that correspond respectively to the first and second ambient light signals.

[0009] In a further embodiment of any of the above, the first and second fields of view respectively capture left and right sides of a vehicle. Each of the first and second fields of view include at least a portion of Class II and/or Class IV views.

[0010] In a further embodiment of any of the above, the first and second displays each include a backlight. The first and second brightnesses are provided by the backlight of its respective first and second displays.

[0011] In a further embodiment of any of the above, the first and second displays each include pixels, and the controller is configured to adjust the first and second brightnesses by changing pixel intensity of the pixels. [0012] In a further embodiment of any of the above, the first and second ambient light sensors are integrated into its respective first and second display.

[0013] In a further embodiment of any of the above, the first and second ambient light sensors are provided on a portion of its respective first and second display at a location other than a backside of the first and second display.

[0014] In a further embodiment of any of the above, the first and second displays are respectively mounted on left and right A-pi liars within a vehicle cab.

[0015] In a further embodiment of any of the above, the controller is provided in at least one of the first and second displays.

[0016] In a further embodiment of any of the above, the controller is provided at a location outside of the first and second displays.

[0017] In another exemplary embodiment, a method of controlling display brightness in a camera monitor system, the method includes detecting first and second ambient light conditions respectively in a region of first and second displays that are arranged in a vehicle cabin, and adjusting a brightness of at least one of the first and second displays based upon the both of the first and second ambient lights.

[0018] In a further embodiment of any of the above, the region of each of the first and second displays is in proximity to opposing A-pillars.

[0019] In a further embodiment of any of the above, the detecting step is performed at locations on the first and second displays.

[0020] In a further embodiment of any of the above, the method includes a step of calculating first and second display brightness based upon the first and second ambient light conditions, and determining which of the first and second display brightnesses is greater. The adjusting step includes increasing the brightness of the one of the first and second displays that is darker than the other of the first and second display brightness.

[0021] In a further embodiment of any of the above, the brightness of the darker display is increased by half the difference between the first and second ambient lights.

[0022] In a further embodiment of any of the above, the brighter of the first and second display is not adjusted. [0023] In a further embodiment of any of the above, the adjusting step is performed based upon a preset cabin illumination value.

[0024] In a further embodiment of any of the above, the calculating step is performed based upon a configurable lookup table.

[0025] In a further embodiment of any of the above, the method includes filtering jitter from first and second signals respectively from the first and second ambient light sensors.

[0026] In a further embodiment of any of the above, the method includes filtering spike from first and second signals respectively from the first and second ambient light sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0028] Figure 1A is a schematic front view of a commercial truck with a camera monitor system (CMS) used to provide at least Class II and Class IV views.

[0029] Figure 1 B is a schematic top view of a commercial truck with a camera monitor system providing Class II, Class IV, Class V and Class VI views.

[0030] Figure 2A is a schematic top view of a vehicle cabin including displays.

[0031] Figure 2B is a perspective view of one example display according to the disclosed camera monitor system (CMS).

[0032] Figure 3 is a flowchart illustrating a method of controlling display brightness in the CMS.

[0033] Figure 4 is a graph illustrating a spike filter in the CMS with display brightness control, where Y-axis is lux and X-axis is sample number.

[0034] Figure 5 is a graph illustrating a jitter filter in the CMS with display brightness control, where Y-axis is lux and X-axis is sample number.

[0035] The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0036] A schematic view of a commercial vehicle 10 is illustrated in Figures 1A and 1 B. The vehicle 10 includes a vehicle cab or tractor 12 for pulling a trailer 14. It should be understood that the vehicle cab 12 and/or trailer 14 may be any configuration. Although a commercial truck is contemplated in this disclosure, the invention may also be applied to other types of vehicles. The vehicle 10 incorporates a camera monitor system (CMS) 15 (Fig. 2A) that has driver and passenger side camera arms 16a, 16b mounted to the outside of the vehicle cab 12. If desired, the camera arms 16a, 16b may include conventional mirrors integrated with them as well, although the CMS 15 can be used in some examples to entirely replace mirrors. In additional examples, each side can include multiple camera arms, each arm housing one or more cameras and/or mirrors.

[0037] Each of the camera arms 16a, 16b includes a base that is secured to, for example, the cab 12. A pivoting arm is supported by the base and may articulate relative thereto. At least one rearward facing camera 20a, 20b is arranged respectively within camera arms 16a, 16b. The exterior cameras 20a, 20b respectively provide an exterior field of view FOVEX-I, FOVEX2 that each include at least one of the Class II and Class IV views (Fig. 1 B), which are legal prescribed views in the commercial trucking industry. The Class II view on a given side of the vehicle 10 is a subset of the class IV view of the same side of the vehicle 10. Multiple cameras also may be used in each camera arm 16a, 16b to provide these views, if desired. Class II and Class IV views are defined in European R46 legislation, for example, and the United States and other countries have similar drive visibility requirements for commercial trucks. Any reference to a “Class” view is not intended to be limiting, but is intended as exemplary for the type of view provided to a display by a particular camera. Each arm 16a, 16b may also provide a housing that encloses electronics, e.g., a controller, that are configured to provide various features of the CMS 15.

[0038] First and second video displays 18a, 18b are arranged on each of the driver and passenger sides within the vehicle cab 12 on or near the A-pillars 19a, 19b (generally, A-pillar 19) to display Class II and Class IV views on its respective side of the vehicle 10, which provide rear facing side views along the vehicle 10 that are captured by the exterior cameras 20a, 20b.

[0039] If video of Class V and/or Class VI views are also desired, a camera housing 16c and camera 20c may be arranged at or near the front of the vehicle 10 to provide those views (Fig. 1 B). A third display 18c arranged within the cab 12 near the top center, left or right of the windshield can be used to display the Class V and Class VI views, which are toward the front of the vehicle 10, to the driver. The displays 18a, 18b, 18c (generally, display 18) face a driver region 24 within the cabin 22 where an operator is seated on a driver seat 26. The location, size and field(s) of view streamed to any particular display may vary from the configurations described in this disclosure and still incorporate the disclosed invention.

[0040] If video of Class VIII views is desired, camera housings can be disposed at the sides and rear of the vehicle 10 to provide fields of view including some or all of the Class VIII zones of the vehicle 10. In such examples, the third display 18c can include one or more frames displaying the Class VIII views. Alternatively, additional displays can be added near the first, second and third displays 18a, 18b, 18c and provide a display dedicated to providing a Class VIII view.

[0041] Referring to Figures 2A and 2B, each display 18a, 18b (and perhaps others, if desired) includes a housing 32 mounted to its respective A-pillar 19 by a bracket 33, for example, or integrated into vehicle trim. A screen 34 is mounted in a front of the housing 32 facing the driver. The screen 34 can be any suitable screen such as TFT, LCD, LED, OLED and others. Each type of screen typically employs some approach for adjusting perceived brightness. For example, if each display 18 is an LCD, the screen will typically include a backlight 36 that can be adjusted to make the screen 34 more visible to the driver in various ambient light conditions. Low ambient lighting conditions use relatively little backlight as compared to bright ambient lighting conditions.

[0042] To provide automatic adjustment of a display’s brightness, each display 18a, 18b respectively includes a first and second ambient light sensor 28a, 28b (generally, ambient light sensor 28) configured to sense an amount of ambient light in a region around the display. The ambient light sensors 28 are arranged to detect light in the environment around the displays 18. Environmental light conditions, such as bright sunshine, may make it difficult for the driver to view the images on one or both the displays 18. In an LCD display, for example, the brightness of the display 18 is using a backlight 36. Other display adjustments are possible, as will be appreciated below. The ambient light sensor 28 can be mounted on the A-pillar, dash or other location; however, providing the ambient light sensor 28 on the front of the housing 32, so that the A-pillar does not obstruct light to it, should most closely approximate the ambient light near the screen 34. Although only one ambient light sensor 28 is shown for each display 18, more ambient light sensors may be used, if desired.

[0043] The disclosed CMS 15 operates to improve display visibility to the driver in different ambient lighting conditions. Typically digital rearview (or front or side) displays adjust brightness level individually based on a light sensor that measure surrounding light. However, when the light is coming from one side of the vehicle, like low setting sun, automatic brightness adjustments to each display based upon its individual, independent ambient light sensor may not provide satisfactory brightness adjustment for the multiple CMS displays. For example, bright sunlight from one side may result in one monitor receiving a lot of light causing an automatic high brightness adjustment for that display (as expected), but the other displays ambient light sensor may be in shadow, resulting in a low brightness level. This can be a problem for the driver because this darker monitor needs to be bright as well, since the driver’s eyes are adjusting to the surrounding light both in and outside of the cabin. When one or more displays is too dark this makes it harder for the driver to see important information in any dark displays, like other cars, people, bicycles, etc. [0044] The overall brightness of the displayed image on the screen can be adjusted using a variety of display elements, such as contrast, brightness (intensity of individual pixels), and a backlight. In the example CMS 15, if an LCD screen is used the backlight 36 is used to adjust the display brightness for a given ambient light condition. Again, it should be understood though that brightness may be provided and adjusted using other techniques. One typical brightness setting can be expressed according to the table below based upon the ambient light sensor signal in the region of the display 18.

TABLE 1

BRIGHTNESS (%)

[0045] The “offset %”, if optionally provided in a particular system, corresponds to a preset cabin illumination value for a cabin that has user adjustable interior cabin lighting (e.g., instrument cluster brightness, switch/user interface brightness, etc.). Older vehicles utilized a rheostat to adjust interior cabin lighting brightness, and newer vehicles typically provide this adjustability digitally via a settings menu in the infotainment system, for example. In the example shown in Table 1 , five “brightness curves” are provided (0%, 25%, 50%, 75%, 100%). This allows the driver to choose to have an overall brighter or darker display based on driver selected brightness preferences. For example, if a 50% offset is selected as the preset cabin illumination value (i.e., interior cabin brightness dimmed by half), then the display brightness is selected based upon display brightness values in that offset row (left or right within that row). So an ambient light sensor for a given display that detects 10 lux with a 50% offset, would provide an initial display brightness with 50% intensity for that display. This optional offset can be added either to a single display or to all displays depending on the configuration. Of course, just one setting (i.e., no reference to cabin illumination) can be used, thus providing no offset.

[0046] The above Table 1 values are interpolated, as needed, based upon the sensed ambient light and the chosen offset, if available since offset is optional. The 0.1 lux point defines the brightness during night. The range 0 to 1 lux (or up to 0.1 lux, for example) are brightnesses applied during dusk/dawn conditions, which depends on many aspects like chosen sensor, tinted glass attenuation, and sampling. The disclosed method of brightness adjustment is applied-in the full range of ambient light conditions.

[0047] Referring to Figure 3, a method 100 of controlling display brightness in the CMS 15 includes detecting first and second ambient lights respectively in a region of first and second displays 18a, 18b (block 102). In one example method of operation, every update cycle the controller calculates displays initial brightness based on detected ambient light and offset using a configurable brightness table (Table 1 ) (block 104). Once the initial brightness of each display has been calculated (i.e., the initial brightness for each monitor determined based upon the Table 1 ambient light sensed values), the controller determines which display has the initial greatest brightness (block 106). To balance out the display brightness, the brightness of the darker monitor is “pulled” up. If the initial display brightness values are the same, then the difference would simply be equal 0 and no balancing would occur. It should be understood that the above method may be used to balance monitor brightness in systems having more than two monitors.

[0048] As described above, if the calculated initial brightness is different than one another, then the brightness of at least one of the displays is adjusted based upon the comparison (block 108). This adjustment can be performed by increasing the brightness of the darker display, for example.

[0049] The above method is an example that first uses calculated display brightness for brightness balancing. To achieve same functionality, the detected first and second ambient lights can be used directly to determine the brightest display and needed display brightness adjustment (i.e., step 104 may be omitted).

[0050] Ambient light sensed below 1 lux, for example, corresponds to dark/dusk/dawn ambient light conditions, which are typically in need of better adjustment of the displays, which is accomplished by comparing the ambient light readings from both display’s 18a, 18b ambient light sensors 28a, 28b. In order to overcome issues with one of the displays 18 being too dark during low light conditions the brightness of the displays 18a, 18b is balanced. In one example, the display brightness balancing algorithm (Equation 1 ) checks which display is the brightest and then adjusts the darker display according to the following formula (brightness increased half the difference):

BRT_NEW = BRTJDLD + (BRT_MAX - BRT_OLD)/2 (Equation 1 ). where:

BRT_NEW is the new, calculated brightness % for the darker display,

BRT_OLD is the brightness % of the darker display prior to adjustment and based upon the darker display’s associated ambient light sensor, and

BRT_MAX is brightness % of the lighter display based upon the lighter display’s associated ambient light sensor.

Example 1 :

Driver display brightness at sensed driver ambient light sensor of 2 lux is 20% according to Table 1 .

Passenger display brightness at sensed driver ambient light sensor of < 2 lux is 16% according to Table 1 .

According to Equation 1 , passenger display is adjusted to 18% brightness at < 2 lux, i.e., 16% + (20% - 16%)/2 = 18%

Example 2:

Driver display brightness at sensed driver ambient light sensor of

1 lux is 16% according to Table 1 .

Passenger display brightness at sensed driver ambient light sensor of < 1 lux is 8% according to Table 1 .

According to Equation 1 , passenger display is adjusted to 12% brightness at < 1 lux, i.e., 8% + (16% - 8%)/2 = 12%

[0051] In the above example, the display having the greater initial brightness is not adjusted and the brightness of the darker display is increased by half the difference in initial brightnesses of the first and second displays 18a, 18b. With the above implementation not only performance during low light conditions is improved but in addition both display brightness is more homogeneous to the driver’s perspective, which is valuable with strong directional light (for example, during sunrise or sunset).

[0052] Brightness balancing is only performed when all ambient light sensors are working correctly and there are no other inhibitions. Centralized and decentralized processing configurations can be used to perform the disclosed method. For example, the controller 30 is provided in at least one of the first and second displays 18a, 18b, that is, in one or both displays. In another example, the controller 30 is provided at a location outside of (i.e., arranged remotely from) the first and second displays 18a, 18b.

[0053] Because of steep gradients between configuration points and issues with flickering additional filtering is implemented by using a spike filter and/or a jitter filter, shown in Figures 4 and 5.

[0054] The spike filter (Fig. 4) will filter input signal changes that are equal to or exceed three times the previous sample, so if the new sample is three times bigger or three times smaller (smaller than 1 /3 ^rd of the old one) then it will be filtered. In one example, the spike filter is allowed to only filter 2 samples (200 ms) each 2 second moving window (timeout), started after first filtered sample. Since the filtering is done in real-time and not retrospectively such limitation needs to be added in order not to filter out whole rising or falling slope. The number of allowed samples to be filtered was chosen so as to not introduce delay when reacting to brightness changes in order to meet the performance requirements.

[0055] For a jitter filter (Fig. 5), the new input value will only be used if it is at least three times bigger or three times smaller (smaller than 1 /3 ^rd of the old one) than the previous sample. Such filtering will discriminate fluctuations of the input signal. During night lighting conditions, the new value will be used if it is equal or exceeds 2-4 lux, for example.

[0056] As described above, the controller 30 (“controller” may generally be referenced as “30”) is in communication with the first and second displays 18a, 18b and in communication with the first and second ambient light sensors 28a, 28b. The controller 30 is configured to calculate and compare the first and second display brightness respectively and is configured to adjust at least one of the first and second brightnesses of the displays 18 based upon the disclosed method to improve visibility to the driver.

[0057] It should be noted that the described controller 30 can be used to implement the various functionality disclosed in this application. The controller 30 may include one or more discrete units.

[0058] In terms of hardware architecture, such a computing device can include a processor, memory, and one or more input and/or output (I/O) device interface(s) that are communicatively coupled via a local interface. The local interface can include, for example but not limited to, one or more buses and/or other wired or wireless connections. The local interface may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers to enable communications. Further, the local interface may include address, control, and/or data connections to enable appropriate communications among the aforementioned components.

[0059] The controller 30 may be a hardware device for executing software, particularly software stored in memory. The controller 30 can be a custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the controller, a semiconductorbased microprocessor (in the form of a microchip or chip set) or generally any device for executing software instructions.

[0060] The memory can include any one or combination of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and/or nonvolatile memory elements (e.g., ROM, hard drive, tape, CD- ROM, etc.). Moreover, the memory may incorporate electronic, magnetic, optical, and/or other types of storage media. The memory can also have a distributed architecture, where various components are situated remotely from one another, but can be accessed by the processor. [0061] The software in the memory may include one or more separate programs, each of which includes an ordered listing of executable instructions for implementing logical functions. A system component embodied as software may also be construed as a source program, executable program (object code), script, or any other entity comprising a set of instructions to be performed. When constructed as a source program, the program is translated via a compiler, assembler, interpreter, or the like, which may or may not be included within the memory.

[0062] The disclosed input and output devices that may be coupled to system I/O interface(s) may include input devices, for example but not limited to, a keyboard, mouse, scanner, microphone, camera, mobile device, proximity device, etc. Further, the output devices, for example but not limited to, a printer, display, etc. Finally, the input and output devices may further include devices that communicate both as inputs and outputs, for instance but not limited to, a modulator/demodulator (modem; for accessing another device, system, or network), a radio frequency (RF) or other transceiver, a telephonic interface, a bridge, a router, etc.

[0063] When the controller 30 is in operation, the processor can be configured to execute software stored within the memory, to communicate data to and from the memory, and to generally control operations of the computing device pursuant to the software. Software in memory, in whole or in part, is read by the processor, perhaps buffered within the processor, and then executed.

[0064] Every cycle the individual brightness is determined for each display (e.g., according to Table 1 ), after which an adjustment function is executed to increase the brightness of the darker display(s). The brightness “pull up” in a disclosed example is set to half of the difference, but does not need to be limited to half. This method works with all values between 0% and 100%, but at low % values the positive effect may be limited.

[0065] The connection/correlation of display brightness level between multiple displays ensures the displays work together to adjust brightness level. This method could be performed with two displays, three displays, four displays or more. The display brightness integration between multiple displays helps the driver to see important information during setting or rising sunlight conditions when the light is coming from the side of the vehicle to prevent one or more displays from being otherwise too dark as with a typical system.

[0066] It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention.

[0067] Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples.

[0068] Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.