In conventional vehicle door lock assemblies, a mechanically operable handle is activated by the vehicle passenger to facilitate entry to, or exit from, the vehicle.

The handle is coupled to a mechanical linkage, such as an arm or rod, which connects with a movable latch component mounted upon the vehicle door. The latch component on the vehicle door is co-operable with a mateable latch component that is fixed to the main body of the vehicle. For example, in a front vehicle door lock assembly the fixed latch part of the lock assembly is often mounted on a vehicle pillar, between the front and rear vehicle doors.

Conventional vehicle lock assemblies also include a key activatable lock component. The lock component is movable into a locked position in which it engages with the latched components to prevent them from de-coupling upon activation of the handle. In this locked state of the latch components opening of the vehicle door is prevented, whether for entry to or access from the vehicle.

More recently, mechanical lock assemblies of the aforementioned type have been superseded by more sophisticated central locking systems, which are concerned, in particular, with easing passenger entry to the vehicle. In such systems an electrically actuable locking mechanism is employed to enable a vehicle user to unlock the vehicle door remotely, without the requirement for a key. The latch mechanisms are similar to those in conventional systems and, thus, in order to open the door when it is unlocked, it is necessary to operate a mechanical handle so as to actuate the mechanical arm and unlatch the latched parts.

It is one object of the present invention to provide an improved vehicle door lock assembly that eases opening of the vehicle door from inside the vehicle.

According to a first aspect of the invention there is provided a lock assembly for a vehicle door for permitting opening of the door from the vehicle interior, the lock assembly including: electrically operable latch means operable between a latched state in which opening of the door is prevented and an unlatched state in which opening of the door is permitted, illuminable push-type switch means operable to control the latch means, and control means for controlling the switch means and disabling the switch means in response to vehicle motion above a predetermined threshold speed so as to prevent actuation of the latch means to the unlatched state in such circumstances.

The invention provides a convenient means for enabling door opening, and passenger exit, from inside the vehicle, as the process of opening the vehicle door involves applying a force to the push-type switch device to de-couple the latched parts and then continuing to apply an opening force to the door to effect opening thereof. Opening of the door can therefore be achieved effectively by just a single action.

Providing an electrical switch means which illuminates in dependence upon the speed of the vehicle means that, when said switch means is in an unlatched state (and hence illuminated), it is easy for a vehicle passenger to identify where pressure should be applied to the switch device to effect opening of the door.

In a preferred embodiment, the latch means includes a first movable latch part for latched engagement with a second latch part, the first movable latch part being actuable by means of an actuator.

In a further preferred embodiment the first latch part is adapted for mounting upon the vehicle door and the second latch part is adapted for mounting upon a fixed part of the vehicle.

Preferably, the control means is configured to generate an activate control signal to illuminate the electrical switch means only in circumstances in which vehicle motion is no greater than the predetermined threshold speed.

In one embodiment the push-type switch means includes means for displaying a textual indication, so that when the switch device is illuminated a word, such as'press'or'open', is displayed to the passenger.

The push-type switch means may include one of (i) an eletroluminescent switch device or (ii) a light emitting diode, such as a light emitting polymer device.

In one particular embodiment the push-type switch means includes a light emitting device for emitting radiation for transmission through a fibre optic link, whereby application of pressure to the fibre optic link serves to unlatch the electrically operable latch means to enable door opening in circumstances in which vehicle motion is no greater than the predetermined threshold speed.

The vehicle door typically has an interior door panel, and in one embodiment the push-type switch means includes a pressure sensitive pad adapted for mounting on the interior door panel so as to be substantially indistinguishable from the panel in circumstances in which said electrical switch means is not illuminated.

For example, the pressure sensitive pad may be mounted behind the trim or covering of the interior door panel, so that it is visible only when illuminated.

The appearance of the door is not affected by the provision of the switch device as the electrical switch means is only illuminated in circumstances where the vehicle is stationary (or near stationary) and otherwise remains substantially hidden.

Conveniently, the pressure sensitive pad may be mounted on an arm rest or ledge of the interior door panel. The pad may, for example, be mounted in the proximity of a further switch means for activating electric windows of the vehicle.

In an alternative application of the lock assembly, the push-type switch means is adapted for mounting on a fixed part of the vehicle. For example, the push-type switch means may be adapted for mounting on a pillar of the vehicle between front and rear vehicle doors thereof.

This embodiment provides the advantage that there is no need for electrical wiring to be provided behind the internal door panel as the electrical connections to the latch arrangement are only required to be made to a fixed part of the vehicle (e. g. the pillar).

Preferably, the actuator is of the electromagnetic type, in which the passage of current-through a winding or solenoid causes movement of the movable latch part. The use of other electric actuators is also envisaged, for example piezoelectric actuators.

According to a second aspect of the invention, there is provided a drive circuit for a vehicle door lock assembly as claimed in the accompanying claim set, the drive circuit including: illuminable push-type switch means operable to control the latch means of the lock assembly, and control means for controlling the switch means and disabling the switch means in response to vehicle motion above a predetermined threshold speed so as to prevent actuation of the latch means into the unlatched state in such circumstances.

According to a third aspect of the invention, there is provided a vehicle door provided with a lock assembly as claimed in the accompanying claim set, wherein the door has the push-type switch means mounted thereon.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a vehicle door provided with a lock assembly of a first embodiment of the present invention, in circumstances in which the vehicle is stationary, Figure 2 is a schematic diagram of a vehicle door provided with a lock assembly of the first embodiment, in circumstances in which the vehicle is moving above a predetermined threshold speed, Figure 3 is a schematic diagram of a vehicle door provided with a lock assembly of a second embodiment of the present invention, in circumstances in which the vehicle is stationary, and Figure 4 is schematic diagram of a part of a vehicle door to illustrate an alternative location for the pressure sensitive switch in Figures 1,2 and 3.

Referring to Figure 1, a vehicle door, referred to generally as 10, includes a first end 12 that is hingedly mounted on the main vehicle body (not shown) and a second end 14 that is permitted to move freely relative to the vehicle body by a restricted amount. The door includes an internal door panel 16 having an interior door surface which is designed to have aesthetic appeal.

The vehicle door is provided with an electrical door lock assembly, which includes an electrically actuable latch arrangement, referred to generally as 18.

The latch arrangement 18 is not shown in detail but includes a first electrically operable latch part that is co-operable with a second fixed latch part. The movable part of the latch arrangement 18 is mounted at the second end 14 of the vehicle door and the fixed latch part is mounted on a fixed part of the vehicle body. For example, if the vehicle door 10 forms the front door of a vehicle, the fixed latch part may be mounted on what is commonly referred to as the B-pillar between the front and rear vehicle doors.

--The movable latch part of the electrical latch arrangement is actuated by means of an electromagnetic actuator 20, which is also mounted upon the second end 14 of the vehicle door. The actuator 20 is not shown in detail but includes an electromagnetic winding or solenoid through which a current is passed to cause movement of the movable latch part, either through magnetic attraction or repulsion depending on the direction of current flow through the winding. The movable latch part is spring-biased into latched engagement with the fixed latch part and, upon energisation of the winding, the movable latch part is caused to move against the spring force to unlatch from the fixed latch part.

A drive circuit for the electrical latch arrangement 18 includes electrical switch means in the form of an electroluminescent switch device 22 which is mounted within a recess in the door panel 16 so as to be generally flush with the surface thereof. The electroluminescent switch device 22 is a push-type switch device, which is caused to close to complete an electrical circuit by the simple action of applying pressure to, or'pushing', a pressure-sensitive pad. The switch device 22 also includes an electroluminescent membrane which is caused to illuminate upon a voltage being applied across it. The switch device 22 becomes visible to a passenger of the vehicle through the panel 16 when it is illuminated. If the switch device 22 is not illuminated it is generally indistinguishable from the remainder of the door panel 16, and so forms a substantially hidden switch in such circumstances. Figures 1 and 2 compare the vehicle door lock assembly when the switch device 22 is illuminated (Figure 1) and when the switch device 22 is not illuminated (see dashed lines in Figure 2).

A first electrical connecting wire 24a connects the electromagnetic winding of the actuator 20 with the electroluminescent switch device 22 and a second electrical connecting wire 24b connects the electroluminescent switch device 22 to a power supply (not shown) of the vehicle, for example the vehicle battery. Activation of the switch device 22 to cause it to illuminate is controlled by means of a control module or unit (also not shown) which communicates, electrically, with the ABS sensor or speed sensor of the vehicle.

The control module for the drive circuit is configured to control the electroluminescent switch device 22 in dependence upon the speed at which the vehicle is moving, and for this purpose is provided with a means for disabling the electroluminescent switch device 22 in circumstances in which the vehicle speed exceeds a predetermined amount. The control module includes a memory for storing a pre-stored threshold speed value (referred to as'the threshold speed') and a comparator.

In use, the control module receives a signal from the engine management system which is indicative of vehicle speed and the comparator compares this measured speed with the threshold speed. Typically, as it is considered to be safe to open a vehicle door only when a vehicle is stationary, the threshold speed is selected to be zero. Hence, if the control module determines that the vehicle is stationary, the control module generates an activate control signal for the electroluminescent switch device 22, causing a voltage to be applied across the membrane to illuminate the switch device. The switch device 22 is then said to be in an activated or'unlocked'state. In such circumstances the application of pressure to the pressure sensitive pad of the switch device 22 causes the switch device 22 to close and results in current flow through the switch device 22 to the actuator 20.

As a result of current being supplied to the actuator 20, the movable latch part of the electrical latch arrangement 18 is caused to move out of latched engagement with the fixed latch part, and de-coupling of the latched parts enables the door 10 to be opened when pushed outwardly from the interior of the vehicle. It will be appreciated that in order to open the door 10 from the interior of the vehicle, the passenger need apply only a limited pressure to the pressure sensitive pad of the switch device 22 to close it when in its activated (illuminated) state and, subsequently and in a continuous action, an outwardly opening force to the vehicle door 10 to pivot the second end 14 thereof relative to the first, hinged end 12. The operation of opening the vehicle door 10 is therefore effected by a single, continuous action which is quick, convenient and requires little effort.

If the control module determines that the vehicle is moving (i. e. the speed of the vehicle is greater than the threshold speed), the activate control signal is not provided to the electroluminescent switch device 22. In the absence of a voltage being supplied across the electroluminescent switch device 22 it remains unilluminated and the door takes the appearance shown in Figure 2, where the switch device 22 is indistinguishable from the remainder of the door panel 16. In such circumstances the switch device 22 is said to be in a deactivated or locked state. In the event that pressure is applied to the pressure sensitive pad of the switch device 22 in such circumstances no current is able to flow therethrough to the actuator 20 and so the latched parts of the electrical latch arrangement 18 remain coupled together. Thus, when the vehicle is moving, a passenger of the vehicle who applies pressure to the pressure sensitive pad of the hidden switch device 22, whether inadvertently or deliberately, is unable to open the door as the parts are held in a locked state. The control module of the system is therefore provided with a means for disabling the electroluminescent switch device 22 in circumstances in which the vehicle is in motion.

In an alternative embodiment, it would be possible to set the threshold speed to be a crawling speed of the vehicle, so that a passenger is not only able to unlock and open the door when the vehicle is stationary but is also able to unlock and open the door if the vehicle is moving very slowly.

The present invention thus provides a convenient and easy to use handle-less door lock system for the interior of the vehicle, which is operable in dependence upon vehicle speed to ensure inadvertent unlocking, and hence opening, of the door during significant vehicle motion is avoided. It is one benefit of the present invention that the use of the electrical latch arrangement 18 avoids the requirement for an internal door handle, and also the mechanical linkage, to enable door opening. A cost and weight saving benefit is also therefore achieved, in comparison with mechanical, handle-based vehicle lock systems.

The illumination aspect of the electrical switch means is particularly advantageous because the electrical switch device 22 of the vehicle door is illuminated clearly for the passenger to press when it is safe for the door to be opened. This provides a particular benefit at night, in other circumstances when light levels are low or for passengers with poor vision. It is a further advantage that illumination of the switch device 22 only occurs in circumstances when one would wish to open the door and it is safe to do so (e. g. when the vehicle is stationary), and therefore does not prejudice the appearance of the interior door panel 16 when the vehicle is in motion and the switch device 22 is hidden.

In the event of failure of the power supply to the actuator 20, for example in an accident situation, it is necessary to ensure that the door 10 can still-bue opened by a passenger inside the vehicle who needs to get out. For this purpose a back up or secondary power supply means may be provided to power the vehicle lock assembly. Typically, the back up power supply means may take the form of a so- called'super capacitor', which provides a means for storing energy derived from the power supply in normal circumstances and for providing a controlled release of energy subsequently, should the main power supply fail. Alternatively, a separate localised battery may be provided for the vehicle lock assembly, for example a lithium ion cell or a nickel hydride cell.

As an alternative embodiment to that shown in Figures 1 and 2, Figure 3 shows an embodiment of the vehicle lock assembly in which the electrical switch means is designed so that activation of the electroluminescent switch device 22 results in a textual indication 26 being displayed, for example display of the word"OPEN".

Similar parts to those shown in Figures 1 and 2 are indicated by like reference numerals in Figure 3.

Referring to Figure 4, in another embodiment of the invention the electrical switch means 22 may be mounted within a ledge or arm rest 28 forming part of the interior door panel 16. It is known to provide pressure sensitive switches 30 for electric windows on the arm rest 28, and on vehicle doors of this type the additional electrical switch device 22 can be incorporated relatively easily within the arm rest 28, if necessary making use of existing electrical wiring for the electric windows.

In a further alternative embodiment (not shown) it is possible to mount the electrical switch means for the vehicle lock assembly on the main body of the vehicle, for example on the B-pillar between front and rear vehicle doors. The electrical switch device 22 is operable as described previously to provide the door unlocking/locking function, and this embodiment may be advantageous in that the requirement for electrical connections behind the vehicle door panel 16 is removed. However, with this embodiment of the invention the door opening action requires a two-stage opening process of (i) initially applying pressure to the pillar-mounted switch device 22 to actuate the movable latch part to de- couple from the fixed latch part, and (ii) subsequently applying an outwardly opening force to the vehicle door to effect the opening movement.

In a still further alternative embodiment of the invention, the vehicle lock assembly may also include a separate electrically operable, mechanical lock arrangement, which is activated to engage with the latch arrangement when the parts thereof are in latched engagement with one another. Locking of the latch parts in this manner prevents the latched parts from de-coupling, and hence prevents the vehicle door from being opened, even if the electrical switch device is pressed to close (when in its activated state). This may be achieved using a similar actuation system to that described previously for the latch parts of the electrical latch arrangement 18.

When in its locked state, the locking arrangement (e. g. a locking pin) co-operates with the latched engaged parts of the latch arrangement 18 to prevent de- coupling thereof, and when in its unlocked state the locking arrangement is disengaged from said latchedly engaged parts so that they can be de-coupled upon closure of the switch device 22 to actuate the movable latch. Such electrically operable mechanical locking systems are well known in the art and would be familiar to persons skilled in this field of technology. Again, this embodiment of the invention provides the advantage that the requirement for the mechanical linkage to an internal door handle, and the internal door handle itself, are no longer required.

In any of the aforementioned embodiments, as an alternative to providing a lock assembly having an electroluminescent switch device, light emitting polymer devices (P-LEDs) may be used, which implement plastic thin film technology.

LEDs may also be employed in combination with a fibre optic link or path to provide the push-type switch means. The LED is located at one end of the fibre optic link and is arranged to transmit radiation through the link. The fibre optic link effectively forms the'switch'component of the vehicle lock assembly and is mounted on the vehicle door so as to be substantially indistinguishable from the remainder of the door except when illuminated, as described previously. A detector is located at the other end of the fibre optic link for measuring the intensity of radiation transmitted through the link by the LED.

In order to unlock the vehicle door, the passenger applies pressure to the fibre optic link, this action being equivalent to pushing the pressure sensitive pad of the switch device 22 of the first embodiment of the invention. The depression of the fibre optic link serves to reduce the intensity of radiation that is transmitted through the link to the detector. If the detector senses that the transmitted intensity is attenuated beyond a predetermined amount, an indication is provided that the fibre optic link has been pressed or pushed and so an electrical signal is provided to initiate current flow to the actuator 20, as described previously.

Providing that at this time the activate control signal is provided to illuminate the fibre optic link (i. e. the vehicle is not moving at a speed above the threshold speed), the passenger's action of pushing on the fibre optic link serves to unlock- and subsequently open the door.

The push-type switch means'22 of the lock assembly may be of the pressure- sensitive switch type, as described previously, whereby application of pressure to the switch device 22 causes it to close to complete an electrical circuit so as to permit current flow therethrough. Other similar push-type switch devices to those described, which are activated by a user pushing or pressing on a switch button or pad, may also be employed, for example so-called contact switches or micro switches.