SEAT OCCUPANCY SENSOR

Abstract

A sensor arrangement, as e.g. a seat occupancy sensor, comprises at least two terminals for connecting said sensor assembly to a control unit, and a first switching group of at least two switching units, said at least two switching units of said first switching group being connected together in such a way as to implement a first logical AND gate. According to the invention the sensor arrangement further comprises at least one second group of at least two switching units, wherein said at least two switching units of said second switching group are connected together in such a way as to implement a second logical AND gate and wherein said first switching group and said at least one second switching group are connected together in such a way as to implement a logical OR gate.

Claims

1. A sensor arrangement comprising: at least two terminals for connecting said sensor assembly to a control unit, a first switching group of at least n switching units, wherein n3 and wherein said at least n switching units of said first switching group being connected together in such a way as to implement a first logical AND gate, and at least one second switching group of at least m switching units, wherein m3 and wherein said at least m switching units of said second switching group are connected together in such a way as to implement a second logical AND gate, wherein said first switching group and said at least one second switching group are connected together in such a way as to implement a logical OR gate, and wherein said sensor arrangement comprises at least one interconnection line, said interconnection line connecting a node arranged between two of said n switching units of said first switching group with at least one node arranged between two of said m switching units of said second switching group.

2. The sensor arrangement according to claim 1, wherein said at least n switching units of said first switching group are connected in series.

3. The sensor arrangement according to claim 1, wherein said first switching group and said at least one second switching group are connected in parallel between said at least two terminals.

4. (canceled)

5. The sensor arrangement according to claim 1, wherein at least one of said switching units comprises a plurality of individually actuatable switching elements connected in parallel between two connection points of said switching unit.

6. The sensor arrangement according to claim 1, wherein at least one of said switching units comprises a foil-type switching element.

7. The sensor arrangement according to claim 1, wherein at least one of said switching units comprises a foil-type pressure sensor for converting a pressure acting on said switching unit into an electrical signal.

8. An automotive vehicle seat, comprising a seat cushion and a seat cover and a sensor arrangement according to claim 1, wherein the said at least n switching units of said first switching group and said at least m switching units of said second switching group are arranged at a certain distance from one another on or in a seating surface of said seat cushion.

9. The automotive vehicle seat according to claim 8, wherein said at least n switching units of said first switching group are arranged in one of a front portion or rear portion of said vehicle seat when seen in driving direction of said vehicle, and wherein said at least m switching units of said second switching group are arranged in the respective other one of a front portion or rear portion of said vehicle seat.

10. The automotive vehicle seat according to claim 8, wherein said at least n switching units of said first switching group are arranged in one of a left portion or right portion of said vehicle seat when seen in driving direction of said vehicle, and wherein said at least m switching units of said second switching group are arranged in the respective other one of a left portion or right portion of said vehicle seat.

11. The sensor arrangement according to claim 1, wherein said at least m switching units of said second switching group are connected in series.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, which show:

[0027] FIG. 1: a simplified circuit diagram of a first exemplary embodiment of a sensor arrangement in accordance with the teaching of the present invention;

[0028] FIG. 2: a possible embodiment of a switching unit;

[0029] FIGS. 3 and 4: a simplified circuit diagram of a different embodiments of a sensor arrangements with interconnection line.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] FIG. 1 shows a simplified circuit diagram of a sensor arrangement, generally references by 10, such as e.g. a seat occupancy sensor, in accordance with the teaching of the present invention. Sensor arrangement 10 comprises at least two terminals 12 and 14 for connecting the sensor assembly 10 to a (not shown) control unit. A first switching group 16 of with a number of basic switch units 16.1, 16.2, 16.3 and 16.4 is arranged and interconnected so as to implement a first logical AND gate between the terminals 12 and 14. The basic switch units 16.1, 16.2, 16.3 and 16.4 are for instance connected in series between the terminals 12 and 14.

[0031] A second switching group 18 of with a number of basic switch 18.1, 18.2, 18.3 and 18.4 is also arranged and interconnected so as to implement a first logical AND gate between the terminals 12 and 14. The basic switch units 18.1, 18.2, 18.3 and 18.4 are for instance connected in series between the terminals 12 and 14. The arrangement is such that the first switching group 16 and the second switching group 18 are connected together in such a way as to implement a logical OR gate, the first switching group 16 and the second switching group 18 may e.g. be connected in parallel between the terminals 12 and 14.

[0032] It will be noted that FIG. 1 represents only a simplified circuit diagram which shows the different switching units of each switching group arranged in a line and an overall symmetric arrangement of the different switching units. In an actual sensor arrangement, the physical arrangement of the switching units may be very different from the shown configuration. Indeed the switching units of a switching group do not need to be aligned in a vehicle seat. Also there is no requirement that the arrangement of the switching units across a seating surface follows a regular pattern or symmetry. Furthermore the sensor arrangement may comprise more than two switching groups, e.g. three switching groups or four switching groups, which are interconnected in such a way as to implement a logical OR gate. Finally the number of switching units per switching group may be different for each of the switching groups.

[0033] The switching units 16.1, 16.2, 16.3, 16.4 and/or the switching units 18.1, 18.2, 18.3 and 18.4 may comprise simple switches, which are activateable by a pressure exerted by an occupant onto a vehicle seat. Some of the switching units 16.1, 16.2, 16.3, 16.4 and/or the switching units 18.1, 18.2, 18.3 and 18.4 or all the switching units 16.1, 16.2, 16.3, 16.4 and/or the switching units 18.1, 18.2, 18.3 and 18.4 may also comprise a plurality of individually actuatable switching elements 20.1, 20.2 and 20.3 connected in parallel between two connection points 22 and 24 of the respective switching unit. Such an embodiment is represented as an example for switching unit 16.1 in FIG. 2. The skilled person will understand that the number of three switching elements for switching unit 16.1 is an arbitrary choice and that the switching unit 16.1 or any other switching unit may comprise a single switching element, two different switching elements or more than three switching elements.

[0034] The effect of connecting the individual switching elements in parallel is that the switching unit is actuated as soon as a single switching element is actuated by a pressure load. If the individual switching elements are arranged in a cluster over a particular zone of the motor vehicle seat, this zone will constitute the active area of the corresponding switching unit. Occupancy of any place within this zone will thus be recognized as occupancy of the switching unit. Such a configuration of the switch units with several individual switching elements enables the extent of the zone wherein seat occupancy can be recognized to be spatially defined.

[0035] In a particularly simple embodiment, the switching units comprise a foil-type switching element. The switching units or switching elements may e.g. take the form of simple switches, such as membrane switches, for example. Such membrane switches comprise for instance a first and a second carrier foil arranged one above the other at a certain distance by means of a spacer and an electrode arrangement with at least two electrodes arranged so that an electrical contact is established between the electrodes if said first and second carrier foils are brought together in response to a pressure acting on said switching element. In an advantageous embodiment of the invention, the switching units or switching elements may comprise foil-type pressure sensors. In this embodiment, in addition to detection of occupancy, information about the intensity of the pressure exerted can also be obtained, enabling more precise classification of the seat occupancy detected.

[0036] Two variants of a preferred embodiment of the sensor arrangement in accordance with the present invention are shown in FIGS. 3 and 4. In this embodiment, the sensor arrangement 10 comprises at least one interconnection line 26, 28 which connects a node arranged between two of the switching units 16.1, 16.2, 16.3, 16.4 of the first switching group 16 with at least one node arranged between two of the switching units 18.1, 18.2, 18.3 and 18.4 of said second switching group 18. By means of the interconnection line or lines, the sensor arrangement allows for different more complex occupancy profiles to be detected as a relevant occupancy. In fact by providing the interconnection lines at suitable nodes between switching units of the different switching groups, the switching units are electrically combined so that complex activation pattern may lead to a detectable signal at the terminals of the sensor arrangement.

[0037] In the embodiment shown in FIG. 3, the interconnection line 26 (shown as a solid line) connects the node between the second switching unit 16.2 and the third switching unit 16.3 with the node between the second switching unit 18.2 and the third switching unit 18.3. Other possible interconnections are shown in dashed lines as 26.1 or 26.2. In the embodiment shown in FIG. 4, the interconnection line 28 (shown as a solid line) connects the node between the first switching unit 16.1 and the second switching unit 16.2 with the node between the third switching unit 18.3 and the fourth switching unit 18.4. Other possible interconnections are shown in dashed lines as 28.1 or 28.2.