# Patent

## Title
Proximity switch based door latch release

## Abstract

A vehicle door latch assembly includes a first proximity sensor on a first side of a door handle and a second proximity sensor on a second side of the door handle. The assembly also includes a latch operative to latch the door closed and to unlatch the door to allow the door to open. The assembly further includes control circuitry for activating the latch to unlatch the door based on an object such as an operator's hand sensed with both the first and second proximity sensors.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. patent application Ser. No. 13/609,390, filed on Sep. 11, 2012, now U.S. Pat. No. 8,922,340, entitled “PROXIMITY SWITCH BASED DOOR LATCH RELEASE.” The aforementioned related application is hereby incorporated by reference.


FIELD OF THE INVENTION
The present invention generally relates to door latch release assemblies, and more particularly relates to a proximity sensor based latch assembly that releases a vehicle door latch to allow the door to open.
BACKGROUND OF THE INVENTION
Automotive vehicles include various door assemblies for allowing access to the vehicle, such as passenger doors allowing access to the passenger compartment. The vehicle doors typically include a mechanical latch assembly that latches the door in the closed position and is operable by a user to unlatch the door to allow the door to open. For example, a passenger may actuate a pivoting release mechanism by pulling on the mechanism to unlatch the vehicle door. The latch may be locked further with a door lock mechanism that typically is actuated with another input by the user.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a method of actuating a vehicle latch assembly is provided. The method includes the steps of detecting a user's hand gripping a handle for a door in a vehicle with proximity sensors on first and second sides of the handle, and actuating a door latch to unlatch the door based on the hand gripping the handle. The method further includes the steps of detecting with the proximity sensors an object in close proximity to the handle, and activating a warning when the object is detected.
According to another aspect of the present invention, a method of controlling a vehicle door latch assembly. The method includes the steps of detecting a hand gripping a door handle in a vehicle with first and second proximity sensors on first and second sides, determining when the vehicle is moving, and performing an action other than activating a door latch to an unlatched position immediately following the detection of a valid hand grip when the vehicle is moving.
According to a further aspect of the present invention, a door latch assembly is provided. The door latch assembly includes first capacitive sensors on a first side of a door handle, a second capacitive sensor on a second side of the door handle, and a latch operative to latch the door closed and to unlatch the door to allow the door to open. The door latch assembly also includes control circuitry for activating the latch to unlatch the door based on an object sensed with the first capacitive sensors and the second capacitive sensor.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a passenger compartment of an automotive vehicle having a vehicle door employing a proximity sensor activated door latch assembly, according to one embodiment;
FIG. 2 is an enlarged side view of the door handle showing the door latch assembly on the grip portion of the door handle;
FIG. 3 is an enlarged partial view of the handle grip portion further illustrating an operator hand gripping the grip portion to unlatch the door;
FIG. 4 is an enlarged cross-sectional view taken through the door handle further illustrating the array of proximity sensors and corresponding activation fields;
FIG. 5 is a schematic diagram of a capacitive sensor employed in each of the proximity capacitive sensors shown in FIGS. 1-4;
FIG. 6 is a block diagram illustrating the door latch assembly, according to one embodiment; and
FIG. 7 is a flow diagram illustrating a routine for activating the vehicle door latch assembly, according to one embodiment.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to a detailed design; some schematics may be exaggerated or minimized to show function overview. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring to FIGS. 1 and 2, an interior of an automotive vehicle 10 is generally illustrated having a passenger compartment and a vehicle door 12 that may be in the closed position as shown in FIG. 1 or may pivot about hinge assemblies (not shown) to an open position to allow access to the passenger compartment. The door 12 has a handle 14 with a grip portion that allows an operator's hand to grip the handle 14 to forcibly swing the door 12 between open and closed positions. The door 12 also includes a latch assembly 20 for latching the door 12 in the closed position to maintain the door closed and for unlatching the door to allow the door to open to an open position. The latch assembly 20 includes an actuatable latch such as an electromagnetic actuated latch 50 that changes the position of the latch between latched and unlatched positions in response to a control signal. While the vehicle 10 is shown having a front driver side door 12, it should be appreciated that the vehicle may be equipped with a plurality of doors each employing the latch assembly 20 as described herein.
The latch assembly 20 employs a plurality of proximity sensors 24 on the grip portion of the handle 14 to allow an operator to actuate the latch 50 to the unlatched position to release the door and allow the door to open. Included are at least first and second proximity sensors on first and second sides of the door handle for sensing an object, such as an operator's hand gripping the handle. Control circuitry activates the latch via a control signal to unlatch the door 12 based on an object sensed with both the first and second proximity sensors 24. As such, the first and second proximity sensors 24 operate together as a proximity switch to switch the latch 50 to the unlatched position when both the first and second proximity sensors detect an adult hand gripping the handle. Additionally, the proximity sensors 24 may be employed to allow an operator to lock and unlock the latch assembly 20 as described herein.
The vehicle 10 further includes one or more warning lights 16, such as light 16 forward of the driver seat shown in the A-pillar in FIG. 1. Warning light 16 may serve as a visual indication of a sensed condition of the proximity sensors such as to indicate an inadvertent contact of an object on one of the first and second sensors. Additionally, one or more audio speakers 18 are provided in the vehicle to provide a chime output warning to provide a sound indication to alert the passenger(s) of an inadvertent contact of an object on one of the sensors as described herein and to alert the driver or occupant of an anticipated activation of the latch when the vehicle is not in park or is in motion.
Referring to FIGS. 2-4, the handle 14 employing the latch assembly 20 is further illustrated having a plurality of proximity sensors 24, also labeled and referred to as first proximity sensors A1-A6 and second proximity sensors B1-B3 arranged on first and second sides 14A and 14B of the grip portion of the handle 14. In one embodiment, a first linear array of proximity sensors A1-A6 are arranged on a first side of the handle 14 and a second linear array of proximity sensors B1-B3 are arranged on a second opposite side of the handle 14. The first array of proximity sensors A1-A6 extends vertically on one side 14A and the second array of proximity sensors B1-B3 extends vertically on the opposite side 14B. The first and second arrays of proximity sensors A1-A6 and B1-B3 are of a size and positioned so as to be engaged by an operator's hand 60 as seen in FIG. 3. As an operator's hand 60 engages and grips the handle 14, the thumb and palm of the hand 60 come into contact or close proximity to one or more of the first array of proximity sensors A1-A6 and the fingers wrap around the handle 14 such that the fingers at an end closer to the proximal tip thereof come into contact or close proximity to the second array of proximity sensors B1-B3. The proximity sensors A1-A6 and B1-B3 thereby detect the simultaneous presence of an operator's hand on both first and second sides 14A and 14B of the handle 14 which is indicative of an operator gripping the handle 14 so as to initiate a latch open activation command to unlatch the latch and thereby releases the door such that the door may open.
In the embodiment shown, the first array of proximity sensors A1-A6 include six sensors and the second array of proximity sensors B1-B3 includes three sensors; however, it should be appreciated that one or more sensors may be employed in each of the first and second arrays of proximity sensors. Additionally, it should be appreciated that the first array of first proximity sensors A1-A6 and the second array of second proximity sensors B1-B3 are on opposite sides 14A and 14B of the handle 14, according to one embodiment. However, the first and second array of proximity sensors may be provided on different sides of the handle where the first side is at an angle greater than ninety degrees (90°) relative to the second side according to other embodiments. It should further be appreciated that the handle 14 and the proximity sensors 24 may be oriented in other directions other than the generally vertical orientation shown herein. It should be appreciated that by applying a second array of proximity sensors B1-B3 on the back side of the door handle in addition to the first array of proximity sensors A1-A6 on the front side of the door handle is achieved with minimal extra costs since both arrays of proximity sensors may be electrically coupled to shared control circuitry and processed together therewith.
The proximity sensors 24 are shown and described herein as capacitive sensors, according to one embodiment. Each proximity sensor 24 includes at least one proximity sensor that provides a sense activation field to sense contact or close proximity (e.g., within one millimeter) of an object, such as the hand (e.g., palm or finger(s)) of an operator in relation to the one or more proximity sensors. Thus, the first and second arrays of capacitive sensors operate as a capacitive switch. The proximity sensors 24 may also detect a swiping motion by the hand of the operator such as a swipe of the thumb or other finger. Thus, the sense activation field of each proximity sensor 24 is a capacitive field in the exemplary embodiment and the user's hand including the palm, thumb and other fingers have electrical conductivity and dielectric properties that cause a change or disturbance in the sense activation field as should be evident to those skilled in the art. However, it should also be appreciated by those skilled in the art that additional or alternative types of proximity sensors can be used, such as, but not limited to, inductive sensors, optical sensors, temperatures sensors, resistive sensors, the like, or a combination thereof. Exemplary proximity sensors are described in the Apr. 9, 2009, ATMEL® Touch Sensors Design Guide, 10620 D-AT42-04/09, the entire reference hereby being incorporated herein by reference.
Referring to FIG. 4, the door handle 14 is shown having the capacitive sensors A1-A6 and B1-B3 formed on the outer surface of an inner substrate 30 of handle 14. Alternatively, the sensors could be formed on the inner surface of an outer covering layer 32 overlaying the inner substrate 30. According to one embodiment, each of the proximity sensors 24 may be formed by printing conductive ink onto the outer surface of the inner substrate 30 which provides the support for the handle 14 such that a user is able to grip the handle 14 and push the handle 14 to open the door 12 or pull the handle 14 to close the door 12. The door handle 14 should be sufficiently rigid and strong to allow an operator to easily swing the door 14 between open and closed positions.
One example of the printed ink proximity sensor 24 is shown in FIG. 5 having a drive electrode 26 and a receive electrode 28 each having interdigitated fingers for generating a capacitive field. It should be appreciated that each of the proximity sensors 24 may be otherwise formed such as by assembling a preformed conductive circuit trace onto a substrate according to other embodiments. The drive electrode 26 receives square wave drive pulses applied at voltage VI. The receive electrode 28 has an output for generating an output voltage VO. It should be appreciated that the electrodes 26 and 28 may be arranged in various other configurations for generating the capacitive field as the activation field.
In the embodiment shown and described herein, the drive electrode 26 of each proximity sensor 24 is applied with voltage input VI as square wave pulses having a charge pulse cycle sufficient to charge the receive electrode 28 to a desired voltage. The receive electrode 28 thereby serves as a measurement electrode. In the embodiment shown, adjacent sense activation fields 70A or 70B generated by adjacent proximity sensors 24 overlap, however, more or less overlap may exist according to other embodiments. When a user or operator, such as the user's hand or thumb or other finger(s), enters an activation field, the latch assembly 20 detects the disturbance caused by the hand or fingers to the activation field and determines whether the disturbance in both activation fields 70A and 70B is sufficient to activate a door unlatch command. The disturbance of each activation field is detected by processing the charge pulse signal associated with the corresponding signal channel. When the user's hand or fingers enters the activation fields 70A or 70B generated by the first and second arrays of sensors A1-A6 and B1-B3, the latch assembly 20 detects the disturbance of each contacted activation field via separate signal channels. Each proximity sensor 24 may have its own dedicated signal channel generating charge pulse counts which may be processed.
Each of the first and second capacitive sensors A1-A6 and B1-B3 is shown generating a sense activation field 70A or 70B. The sense activation fields 70A and 70B generated by each individual sensor in each array are shown slightly overlapping, however, it should be appreciated that the activation fields may be smaller or larger and may overlap more or less depending on the sensitivity of the individual fields. By employing a plurality of activation fields on one or both sides of the handle 14, the size and shape of the hand gripping the handle 14 may be determined based on the size of the object being greater than a predetermined size. The size and shape of the hand can be determined based on the number of sensors contacted and/or amplitude of the activation fields. This enables the latch assembly 20 to determine whether an adult or a child is gripping the handle 14 such that activation of the latch may be prevented when a small handle indicative of a child is determined to be gripping the handle and allowed only when a large hand indicative of an adult is determined to be gripping the handle.
In addition, a gesture or swipe motion of the hand, such as a swipe or gesture motion of one or more of the thumb or other fingers may be determined by employing the plurality of capacitive sensors in one or more of the linear arrays. The operator may move one of the digits, such as the thumb, downward which may be sensed with sequential detection by the plurality of capacitive sensors A1-A6 as the thumb passes through each of the sensor activation fields 70A-70F sequentially to initiate a door lock command to lock the latch in the closed or latched position which prevents the door from opening. Contrarily, a digit, such as the thumb, may be moved upward and detected sequentially by the capacitive sensors 70A-70F indicative of a command to unlock the latch to allow the latch assembly to move to the unlatched position to thereby allow the door to be opened. Similarly, other digits or movement of the hand in general may be employed to move up or down and be detected as a swipe or gesture to initiate lock and unlock commands for the latch assembly 20.
Referring to FIG. 6, the proximity sensor activated latch assembly 20 is illustrated according to one embodiment. The plurality of proximity sensors 24 in sensor arrays A1-A6 and B1-B3 are shown providing inputs to a controller 40, such as a microcontroller. The controller 40 may include control circuitry, such as a microprocessor 42 and memory 48. The control circuitry may include sense control circuitry processing the activation field signal associated with each proximity sensor 24 to sense user activation of each sensor by comparing the activation field signal to one or more thresholds pursuant to one or more control routines. It should be appreciated that other analog and/or digital control circuitry may be employed to process each activation field signal, determine user activation, and initiate an action. The controller 40 may employ a QMatrix acquisition method available by ATMEL®, according to one embodiment. The ATMEL acquisition method employs a WINDOWS® host C/C++ compiler and debugger WinAVR to simplify development and testing the utility Hawkeye that allows monitoring in real-time the internal state of critical variables in the software as well as collecting logs of data for post-processing.
The controller 40 provides an output signal to one or more devices that are configured to perform dedicated actions responsive to detected activation of the proximity sensors on the door handle. The one or more devices may include an electromagnetic door latch 50 that is actuatable to move the latch to a first position or latch position to keep the door closed or to a second or unlatch position to allow the door to open. The electromagnetic door latch 50 may include a conventional electromagnetic actuated latch that moves the latch 50 between the first and second positions based on a control signal from the controller 40. It should be appreciated that other actuatable latches may be employed to move the latch 50 between the first and second positions, such as a pneumatic latch assembly, a motor, or other electrically activated mechanism.
The controller 40 also outputs a control signal to the door lock 52 to activate the door lock between locked and unlocked positions. The electromagnetic latch 50 may be operatively coupled to the door lock 52. When the door lock 52 is in the locked state, the electromagnetic door latch 50 is prevented from moving to the unlatch position. The electromagnetic door latch 50 may only unlatch to the unlatched position when the door lock 52 is in the unlocked position.
The controller 40 further provides output signals to one or more warning lights 16. The warning lights may include one or more LEDs or other light sources at a location visible to the occupant, such as a driver of the vehicle. The warning light(s) may be located in the A-pillar as shown in FIG. 1, or at other suitable locations. Additionally, controller 40 provides an output signal to one or more audio speakers to provide an audible chime sound indicative of a warning. The one or more of the warning lights 16 and speakers 18 may serve as warning indicators to the passengers in the vehicle when an object is detected in close proximity to the proximity sensors such as an inadvertent contact with one sensor or sensor array. The one or more warning lights 16 and speakers 18 may also serve as warning indicators when a potential door unlatch command is detected while the vehicle is not in park and may be moving. The warning may be followed by a time delay such as three seconds prior to unlatching the latch, thereby giving the operator time to consider the intended command.
The controller 40 is further shown having an analog to digital (A/D) comparator 44 coupled to the microprocessor 42. The A/D comparator 44 receives the voltage output VO from each of the proximity sensors 24, converts the analog signal to a digital signal, and provides the digital signal to the microprocessor 42. Additionally, controller 40 includes a pulse counter 46 coupled to the microprocessor 42. The pulse counter 46 counts the charge signal pulses that are applied to each drive electrode of each proximity sensor, performs a count of the pulses needed to charge the capacitor until the voltage output VO reaches a predetermined voltage, and provides the count to the microprocessor 42. The pulse count is indicative of the change in capacitance of the corresponding capacitive sensor. The controller 40 is further shown communicating with a pulse width modulated drive buffer 15. The controller 40 provides a pulse width modulated signal to the pulse width modulated drive buffer 15 to generate a square wave pulse train VI which is applied to each drive electrode of each proximity sensor 24. The controller 40 processes one or more control routines, shown in one embodiment including door latch control routine 100 stored in memory to monitor and make a determination as to activation of one of the proximity switches.
The door latch control routine 100 processes the various proximity sensors 24 and performs a method of sensing user input commanded on each of the proximity sensors and activating control of the latch assembly. Method 100 begins at step 102 and proceeds to decision step 104 to determine if a valid hand gripping is detected on both sides of the handle with the first and second proximity sensors. A valid hand grip may be detected when an object of a sufficient size greater than a predetermined size is detected on both sides of the grip portion of the handle. If a valid hand gripping is detected on the handle by the sensors, method 100 proceeds to decision step 106 to determine if the thumb or other digit on the hand is moving up or down. If the thumb or other digit of the hand is determined to be moving up, method 100 proceeds to step 108 to actuate the door lock up which is indicative of a door unlock command that unlocks the door lock to allow the latch assembly to activate the latch to the door open position. If the thumb or other digit is determined to be moving down, then method 100 proceeds to step 110 to actuate the door lock down which is indicative of a door lock command to prevent the latch from opening. If neither the thumb nor other digit is moving up or down, method 100 proceeds to step 112 to determine if the vehicle is in the park state which is indicative that the vehicle may not be moving. The park state may be determined by the vehicle transmission or by vehicle speed. If the vehicle is in park, method 100 proceeds to step 124 to actuate the door latch to release to thereby allow the door to open. If the vehicle is not in park, method 100 activates a sound danger chime at step 118 to notify the occupants that the vehicle may still be moving at the time that a potential door latch release command is detected. Method 100 then waits for a delay time, such as three seconds before allowing the door latch to be released at step 124. The time delay thereby provides the operator sufficient time to disengage gripping of the handle if door actuation of the latch assembly is no longer the intended command. As such, method 100 will first determine if a valid hand gripping is detected on both sides at step 122 before actuating the door latch release to the unlatched position.
If a valid hand gripping on both sides of the handle is not detected at step 104, method 100 proceeds to decision step 116 to determine if an object is up against either side of the pad and, if so, activates a warning chime and/or light at step 114. Accordingly, if an object inadvertently is in close proximity to one or more of the capacitive sensors, a warning light or sound indicator is provided to the operator such that the operator may move the object from the capacitive sensors and not inadvertently release the latch and open the door.
Accordingly, the door latch assembly method advantageously allow for activation of the latch to unlatch the door based on an object sensed with first and second proximity sensors on first and second sides of the door handle. The system and method advantageously allows a user to effectively open the vehicle door without having to actuate a mechanical input lever, and thereby providing for a robust door release latch having fewer moving parts and which is cost-effective and easy to operate.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.

## Claims

1. A method of actuating a vehicle latch assembly comprising: detecting a user's hand gripping an interior handle for a door m a vehicle with proximity sensors on first and second sides of the handle;
actuating a door latch to unlatch the door based on the hand gripping the handle;
detecting with the proximity sensors an object inside the vehicle not gripping the handle and in close proximity to the handle; and
activating a warning when the object is detected.

2. The method of claim 1, wherein the first side is substantially opposite the second side.

3. The method of claim 1, wherein the latch comprises an electromagnetic latch.

4. The method of claim 1 further comprising the step of detecting when the vehicle is in park, wherein another warning is activated when the vehicle is not in park.

5. The method of claim 4 further comprising the step of waiting for a time delay if the vehicle is moving, and actuating the door latch to unlatch the door following the time delay when a hand is detected gripping the door handle.

6. The method of claim 1 further comprising the step of detecting movement of the hand in a direction on one of the proximity sensors and determining a swipe motion indicative of one of a door lock and unlock command to cause the door latch to lock or unlock based on the command.

7. The method of claim 1 further comprising the step of determining a size of the hand relative to one of the proximity sensors based on a plurality of sensor fields and providing an output signal only when the size exceeds a predetermined size.

8. The method of claim 1, wherein the proximity sensors comprise capacitive sensors.

9. A method of controlling a vehicle door latch assembly comprising:
detecting a hand gripping a door handle in a vehicle with first and second proximity sensors on first and second sides of the door handle;
determining when the vehicle is moving;
waiting for a time delay when the vehicle is moving; and
actuating the door release to the unlocked position following expiration of the time delay.

10. The method of claim 9, wherein the action comprises performing an action other than activating a door latch to an unlatched position immediately following the detection of a valid hand grip when the vehicle is moving.

11. The method of claim 10, wherein the action comprises sounding an alarm.

12. The method of claim 9, wherein the first side is substantially opposite the second side.

13. The method of claim 9 further comprising the step of detecting movement of the hand in a direction on one of the proximity sensors and determining a swipe motion indicative of one of a door lock and unlock command, to cause the door latch to lock or unlock based on the command.

14. The method of claim 9 further comprising the step of determining a size of the hand relative to one of the proximity sensors based on a plurality of sensor fields and providing an output signal only when the size exceeds a predetermined size.

15. The method of claim 9, wherein the proximity sensors comprise capacitive sensors.

16. A door latch assembly comprising:
first capacitive, sensors on a first side of an interior door handle;
a second capacitive sensor on a second side of the door handle;
a latch operative to latch the door closed and to unlatch the door to allow the door to open; and
control circuitry for activating the latch to unlatch the door based on a hand sensed with the first capacitive sensors and the second capacitive sensor, wherein the control circuitry further detects with the first and second capacitive sensors an object inside the vehicle that is not gripping the handle and is in close proximity to the handle, and further activates a warring, when the object is detected.

17. The door latch assembly of claim 16, wherein the second capacitive sensor comprises a plurality of second capacitive sensors.

18. The door latch assembly of claim 16, wherein the assembly determines at least one of a swipe and a hand size based on signals generated by the first capacitive sensors.

19. The door latch assembly of claim 16, wherein the control circuitry determines the hand gripping the handle and further determines if the vehicle is moving and performs an action other than activating the door latch to an unlatched position immediately following the detection of a hand gripping the handle when the vehicle is determined to be moving.