GB2437754A

GB2437754A - A switching arrangement for a storage receptacle of a motor vehicle

Info

Publication number: GB2437754A
Application number: GB0606739A
Authority: GB
Inventors: Thomas Popham; Peter Thomas
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2006-04-04
Filing date: 2006-04-04
Publication date: 2007-11-07
Anticipated expiration: 2026-04-04
Also published as: GB0606739D0; GB2437754B

Abstract

A storage receptacle 13 arranged in a door trim panel 10 of a motor vehicle has an access opening 9, an illumination device 15 and a switching arrangement 16 for sensing a hand entering within the receptacle. The switching arrangement 16 comprises a sensing electrode 17 arranged on the back side 12 of the trim panel 10, a guard electrode 23 facing the sensing electrode 17 and arranged on a front panel 14, a capacitance measuring unit 19 for measuring a capacitive signal at the sensing electrode 17, an unity gain amplifier 27, an electronic switch 25 for alternatively connecting the guard electrode 23 to the sensing electrode 17 via the amplifier 27 or ground 26 in response to a signal command and an ECU 25. The ECU generates the signal command and receives a sequence of capacitive measurements from the capacitance measuring unit 19 according as the guard electrode 23 is connected to ground 26 or to the sensing electrode 17, and to process the sequence of capacitive measurements so as to turn on or turn off the illumination device 15 when a hand enters or leaves the receptacle 13.

Description

Switching arrangement for a storage receDtacle of a motor vehicle The

present invention relates to a switching arrangement for a storage receptacle of a motor vehicle. In particular, the invention relates to a switching arrangement in the storage receptacle adapted to control an illumination device located, for instance, within the storage receptacle by the approach of a human hand.

It is known, for instance from W02004/017521, to install, within a vehicle compartment, a sensing electrode forming part of a capacitor. The sensing electrode is also connected to a detection device that monitors the capacitance to activate a switching device which controls for instance an interior light. The device is able to sense near the sensing electrode any object or hand that is capacitive relative to ground and to actuate the interior light when a minimum capacitance value is measured.

It is a problem with such a known arrangement that when used to control an illumination device for a storage receptacle, for instance a door bin, false triggers can be caused by (i) body parts outside the door bin e.g. leg touching the outside of the door pocket side, (ii) large or conductive objects moving inside the door panel e.g. metallic mechanical window lift mechanism and (iii) static or moving objects inside the door bin e.g. rolling bottle or CD flipping from side-to-side. These false triggers may cause unintended illumination of the door bin and thus a driver distraction.

It is an object of the present invention to provide a switching arrangement for a storage receptacle of a motor vehicle which overcomes or alleviates the aforementioned disadvantage.

According to a first aspect of the invention there is provided a switching arrangement for a storage receptacle of a motor vehicle, the receptacle defining a cavity and an access opening, the switching arrangement comprising a sensing electrode arranged on the receptacle, a guard electrode arranged on the receptacle in such a way that the guard electrode is arranged on an opposite surface of the storage receptacle where is located the sensing electrode and be faced with the sensing electrode, a capacitance measuring means for measuring a capacitive signal at the sensing electrode, an unity gain buffer, an electronic switch means for alternatively connecting the guard electrode to the sensing electrode via the unity gain buffer or ground in response to a signal command and an electronic control module generating the signal command and arranged to receive a sequence of capacitive measurements from the capacitance measuring means according as the guard electrode is connected to ground or to the sensing electrode, and to process the sequence of capacitive measurements so as to operate a switching device.

Such an arrangement ensures to discriminate between a moving or static object within the storage receptacle and a hand approaching the storage receptacle by enhancing the sensivity of the sensing electrode.

Preferably, the electronic control module includes a processor which incorporates a model and decision logic, the model receives the sequence of capacitive measurements and applies the decision logic to produce an output command to the switching device.

According to a second aspect of the invention there is provided an inner trim panel for a motor vehicle, the trim panel having a storage receptacle, the receptacle including a switching arrangement which is in accordance with the first aspect of the invention.

Preferably, the switching device is in use connected to an illumination device arranged to illuminate the interior of the receptacle.

Preferably also the inner trim panel is a trim panel of a vehicle door.

According to a third aspect of the invention there is provided a method of controlling a switching arrangement which is in accordance with the first aspect of the invention, the method comprising the steps of:-(i) providing a signal command to the electronic switch means to switch the guard electrode to ground, (ii) measuring the capacitive signal, (iii) providing a signal command to the electronic switch means to switch the guard electrode to the sensing electrode, (iv) measuring the capacitive signal, (v) inputting the sequence of capacitance measurements received to the model, (vi) applying the decision logic and (vii) producing an output command determined by the decision logic to the switching device.

The invention will now be described by way of example with reference to the accompanying drawings of which: -Fig.1 is a perspective view of a trim panel of a vehicle door having a storage receptacle including an illumination device and a switching arrangement according to the present invention so as to control the illumination device; Fig.2 is a schematic cross-section on the line A-A in Fig.1 with a schematic representation of the switching arrangement located within the storage receptacle; Fig.3 is a schematic graph illustrating a sequence of capacitive measurements depending upon the state of an electronic switch means forming part of the switching arrangement shown in Fig.2; Fig.4 is a time line illustrating capacitance changes measured by the switching arrangement according to different events; and Fig.5 is a graph illustrating the control of the illumination device depending upon the events occurring in Fig.4.

With reference to the Figs.1 to 2, there is shown an inner trim panel 10 of a vehicle door, in particular for the driver side of a vehicle. The trim panel 10 has a body having a front side 11 and a back side 12. The back side 12 of the trim panel 10 is hidden from view by an exterior door panel 8 when the trim panel is attached to a door frame (not shown). n

The trim panel 10 also has in its lower part a storage receptacle 13 that projects from the front side 11 and substantially extends horizontally across a major portion of the width of the panel 10. The storage receptacle 13 has a front panel 14 and an access opening 9.

The storage receptacle 13 is in this example formed as part of the trim panel 10.

An illumination device 15 and a switching arrangement 16 are also attached to the trim panel 10. The illumination device 15 includes at least one light source located in this example within the storage receptacle 13.

The switching arrangement 16 includes a sensing electrode 17 which is formed in this example of foil strip. The sensing electrode 17 is attached, along the length of the storage receptacle 13, on the back side 12 of the trim panel 10. The sensing electrode 17 is connected to a capacitance measuring means 19 which controls a switching device 20 connected to the illumination device 15. The capacitance measuring means 19 includes, in a known manner, a frequency generator, a threshold circuit, a multiplexer and amplifier.

Thus, in a conventional manner, when an operator moves his hand towards the sensing electrode 17, then the current is pulled from the sensing electrode 17 into the body and will be detected by the capacitance measuring means 19 of the sensing electrode 17 generating output signal which will control lighting of the illumination device 15 according to a change of capacitance signal.

If the operator places a full tin can in the storage receptacle 13 there is no significant change of capacitance signal measured at the sensing electrode 17 when the hand leaves the storage receptacle, as the tin can has a capacitance relative to ground close to that of a hand. Hence the illumination device 15 is likely to keep being turned on or to be turned on when the can moves causing a driver distraction. To overcome this problem the switching arrangement 16 further includes a guard electrode 23 and an electronic control module 24 connected to an electronic switch means 25 for alternatively connecting the guard electrode 23 to the sensing electrode 17 or ground 26. The electronic control module 24 is connected between the capacitance measuring means 19 and the switching device 20 to control the illumination device according to logic. The switching arrangement 24 also includes a unity gain buffer, in this example, an amplifier 27 having a high input impedance and a low output impedance. The sensing electrode 17 is connected to the input of the amplifier 27 and the output of the amplifier 27 is connected to the electronic switch means 25. The gain of the amplifier 27 is unity.

The guard electrode 23 is also formed in this example of foil strip which is attached, along the length of the storage receptacle 13, on the interior surface of the front panel 14 of the storage receptacle 13.

The electronic control module 24 includes a processor (not shown) which comprises decision logic and a model such as an empirical model. The empirical model is in this example a neural network model, as well-known by those skilled in the art, which allows the relationships between inputs and outputs to be determined. Measured capacitances of the sensing electrode 17 respectively when the guard electrode 23 is connected to ground 26 and when the guard electrode 23 is connected to the sensing electrode 17 (via the unity gain buffer 27) are inputted into the neural network model that is used in executing the decision logic in the processor.

The electronic control module 24 periodically transmits a command to the electronic switch means 25 in order to alternatively connect the electrode guard 23 either to ground 26 or to the electrode sensing 17 within a predetermined period of time, for instance 5 ms.

This change of state of the electronic switch means 25 allows for a same event the acquisition of a sequence of two capacitive measurements from the capacitive measuring means 19 corresponding respectively when the guard electrode 23 is connected to ground 26 (GND) and when the guard electrode 23 is connected to the sensing electrode 17 (DS) as shown in Fig. 3. This sequence of capacitive measurements provides inputs to allow ) discrimination between certain events, e.g. between a hand in the storage receptacle or an object in the storage receptacle.

Fig. 4 shows time-line plots which illustrate how the capacitance sensed at the sensing electrode 17 changes for various events depending upon the state of the electronic switch means 23. In these plots which show various values plotted against time (t), the line GND shows the capacitance sensed at the sensing electrode 17 when the guard electrode 23 is connected to ground 26 and the line DS shows the capacitance sensed at the sensing electrode 17 when the guard electrode 23 is connected to the sensing electrode 17 via the unity gain amplifier 27, that is where the guard electrode 23 shields part of the sensing electrode 17, since the sensing electrode 17 "sees" its own potential in the direction of the guard electrode 23, the latter being connected to the output of the unity gain amplifier.

The graph shows that no capacitance change is sensed at the sensing electrode 17 for both states of the electronic switch means 25 when nothing is in proximity of the storage receptacle, at time (ta) to time (tb). At time (tb), the operator enters his/her hand into the storage receptacle, the capacitance measuring means 19 detects a capacitance change which is substantially identical according as the guard electrode 23 is connected to ground GND or to the sensing electrode 17 via the unity gain amplifier 27. When the hand leaves the storage receptacle, at time (tc), the same capacitance change is detected according as the guard electrode 23 is connected to ground GND or to the sensing electrode 17 via the unity gain amplifier 27.

When a hand is moving along the exterior side of the storage receptacle, at time (td) to time (te), the capacitance measuring means 19 detects for the same event two different capacitance change signals according to whether the guard electrode 23 is connected to ground 26 (GND) or to the sensing electrode 17 via the unity gain amplifier 27 (DS). At time (tf) to (tg), the operator places a first bottle within the storage receptacle, then at time (th) to (ti), the operator places a second bottle within the storage receptacle, in each event a capacitance change is detected and the hand leaving the storage receptacle is also detected in each event by a decrease of the capacitance signal. As it will be appreciated from the graph, when the guard electrode 23 is switched to ground 26 (line GND), the objects, i.e. the bottles, sit directly between the sensing electrode 17 and the ground, so that a much larger capacitance to ground is detected at the sensing electrode 17 than when the guard electrode 23 is connected to the sensing electrode 17 via the unity gain amplifier 27. At time (tj) to (tk), the effect of an operator's hand over the front side 14 of the storage receptacle is largely insignificant when the guard electrode 17 is connected to ground 26. The increase in capacitance is larger when the guard electrode 17 is connected to the sensing electrode 17 via the unity gain amplifier 27 (line DS) because the limited width of the guard electrode does not fully shield the sensing electrode from the path to ground caused by the hand outside the storage receptacle. At time (tI) to (tm), the operator removes the second bottle from the storage receptacle and at time (tn) to (to) the operator removes the first bottle from the storage receptacle. From time (to) onwards the same capacitance is detected regardless of whether the guard electrode is connected to ground or to the sensing electrode via the buffer 27.

In each event described above, the processor compares the currently received capacitive value with the capacitive value received immediately preceding the currently received value, therebetween the electronic switch means 25 has been activated in order to connect the guard electrode 23 to ground 26 or to the sensing electrode 17 via the unity gain buffer 27. If the processor determines, based on the neural network model, that a hand is moving in or moving out the storage receptacle, it is configured with logic to trigger an adequate command to turn on or turn off the illumination device 15, as illustrated at Fig.4.

It will be appreciated that such arrangement offers to discriminate between objects and the hand of an operator in order to avoid false trigger of the illumination device.

In a modification (not shown), a shielding electrode is attached behind the sensing electrode 17. A dielectric insulating layer is interposed between the sensing electrode 17 and the shielding electrode to insulate the shielding electrode from the sensing electrode 17. Such an arrangement ensures that a window lift mechanism or surrounding metal work arranged between the inner door panel and the exterior door panel will not be detected by the sensing electrode 17 causing false triggers of the illumination devices.

In another modification (not shown), a second guard electrode and a second electronic switch means are added with the switching arrangement to improve the discrimination between objects and an operator's hand. This second guard electrode, which is formed in this example, a foil strip, is attached on the bottom surface of the storage receptacle. This second guard electrode is switched between ground and the sensing electrode 17 via the buffer 27 (or in a modification via a second buffer) by the control module as previously described so as to obtain a sequence of four capacitance measurements from the capacitive measuring means, i.e. when the first guar electrode is connected to ground, when the second guard electrode is connected to ground, when the first guard electrode is connected to the sensing electrode via the buffer 27 and when the second guard electrode is connected to the sensing electrode via the buffer 27. Such a sequence of capacitance measuring will be interpreted by the processor based on an empirical model (such as a neural network model) or a theoretical model.

Although the sensing arrangement has been described herein in relation to a storage receptacle of a door trim panel it will be appreciated that the switching arrangement may be arranged within other inner trim panels including a storage receptacle elsewhere on the vehicle. Furthermore, it will be appreciated that the sensing electrode 17 could be located on the front side 11 of the trim panel 10. Also, the guard electrode 23 could be located on the exterior surface of the front panel 14. It will be noted that the model could be theoretical. Moreover, the neural network model could be replaced by a look-up table.

Claims

CLAI MS

A switching arrangement for a storage receptacle of a motor vehicle, the receptacle defining a cavity and an access opening, the switching arrangement comprising a sensing electrode arranged on the receptacle, a guard electrode arranged on the receptacle in such a way that the guard electrode is arranged on an opposite surface of the storage receptacle where is located the sensing electrode and be faced with the sensing electrode, a capacitance measuring means for measuring a capacitive signal at the sensing electrode, an unity gain buffer, an electronic switch means for alternatively connecting the guard electrode to the sensing electrode via the unity gain buffer or ground in response to a signal command and an electronic control module generating the signal command and arranged to receive a sequence of capacitive measurements from the capacitance measuring means according as the guard electrode is connected to ground or to the sensing electrode, and to process the sequence of capacitive measurements so as to operate a switching device.

2. A switching arrangement as claimed in claim 1 in which the electronic control module includes a processor which incorporates a model and decision logic, the model receives the sequence of capacitive measurements and applies the decision logic to produce an output command to the switching device.

3. A switching arrangement as claimed in claim 2 in which the model is an empirical model or a theoretical model.

4. A switching arrangement as claimed in claim 3 in which the empirical model is a neural network model.

5. A switching arrangement claimed in any one of claims 1 to 4 in which the unity gain buffer is an amplifier having a high input impedance and a low output impedance, the input being connected to the sensing electrode and the output being connected to the electronic switch means.

6. A switching arrangement claimed in any preceding claims in which the sensing electrode and the guard electrode are formed of a foil strip.

7. A switching arrangement claimed in claim 6 in which the foil strip is attached along the length of the storage receptacle.

8. A switching arrangement claimed in any preceding claims in which the switching arrangement further includes a shielding electrode arranged over the sensing electrode.

9. A switching arrangement claimed in any preceding claims in which the switching arrangement further includes a second guard electrode and a second switch means for alternatively connecting the second guard electrode to ground or the sensing electrode via the buffer in response to a second signal command, the electronic control module being arranged to generate the second signal command and receive a sequence of capacitive measurements from the capacitance measuring means according as the guard electrode and the second guard electrode are connected to ground or to the sensing electrode, and to process the sequence of capacitive measurements so as to operate the switching device.

10. An inner trim panel for a motor vehicle, the trim panel having a storage receptacle, the receptacle including a switching arrangement which is in accordance with any one of claims 1 to 9.

11. A trim panel as claimed in claim 9 in which the switching device is in use connected to an illumination device arranged to illuminate the interior of the receptacle. -11 -

12. A trim panel as claimed in any one of claims 9 to 11 in which the trim panel is an inner trim panel of a vehicle door.

13. A trim panel as claimed in claim 12, the inner door being in use connected to an exterior door panel, in which the guard electrode is arranged on the receptacle and the sensing electrode is arranged on the trim panel.

14. A trim panel as claimed in claim 13, the trim panel having a front side and a back side, in which the sensing electrode is arranged on the back side of the trim panel.

15. A trim panel as claimed in claim 14, when the switching arrangement is according to claim 8, in which the shielding electrode is arranged over the sensing electrode so that the shielding electrode prevents operation of the switching device by an object located between the inner door panel and the exterior door panel.

16. A trim panel as claimed in any one of claims 11 to 15, when the switching arrangement is according to claim 8, the storage receptacle having a bottom surface in which the second electrode guard is arranged on the bottom surface of the storage receptacle.

17. A method of controlling a switching arrangement which is in accordance with any one of claims 1 to 9, the method comprising the steps of:-(i) providing a signal command to the electronic switch means to switch the guard electrode to ground, (ii) measuring the capacitive signal, (iii) providing a signal command to the electronic switch means to switch the guard electrode to the sensing electrode, (iv) measuring the capacitive signal, (v) inputting the sequence of capacitance measurements received to the model, (vi) applying the decision logic and (vii) producing an output command determined by the decision logic to the switching device. ) -12-

18. A switching arrangement for a storage receptacle of a motor vehicle substantially as described herein with reference to the accompanying drawings.

19. An inner trim panel for a motor vehicle as described herein with reference to the accompanying drawings.