ROTARY SWITCH FOR A MOTOR VEHICLE

Abstract

The invention relates to a rotary switch (1) for a motor vehicle that has a rotational position detection device, wherein the rotational position detection device has at least a first light-based transmitter/receiver pair (5a), a second light-based transmitter/receiver pair (5b), and a light screening element (15), wherein the light-based transmitter/receiver pairs (5a, b) each have a light transmitter and a light receiver located opposite the light transmitter, such that a light transmission path (27) is formed between each transmitter and receiver, wherein the light screening element (15) determines the transmission properties of the respective light transmission paths (15) based on the rotational positions (D, N, R) of the rotary switch (1), wherein the transmitter/receiver pairs (5a, b) are configured such that a first spacing (d1) extending between a midpoint of the first light transmission path (27a) of the first pair (5a) and a rotational axis (9) of the rotary switch (1) differs from a second spacing (d2) extending between a midpoint of the second light transmission path (27b) of the second pair (5b) and the rotational axis (9).

Claims

1. A rotary switch for a motor vehicle that has a rotational position detection device, wherein the rotational position detection device has at least a first light-based transmitter/receiver pair, a second light-based transmitter/receiver pair, and a light screening element, wherein the first and second light-based transmitter/receiver pairs each have a light transmitter and a light receiver located opposite the light transmitter, such that a light transmission path is formed between each light transmitter and light receiver, wherein the light screening element determines the transmission properties of the respective light transmission paths based on the rotational positions of the rotary switch, wherein the first and second transmitter/receiver pairs are configured such that a first spacing extending between a midpoint of the first light transmission path of the first light-based transmitter pair and a rotational axis of the rotary switch differs from a second spacing extending between a midpoint of the second light transmission path of the second receiver pair and the rotational axis.

2. The rotary switch according to claim 1, wherein the light screening element can move in relation to the first and second light-based transmitter/receiver pairs (5a,b), wherein the relative movement is a rotational movement.

3. The rotary switch according to claim 1, wherein the first light-based transmitter/receiver pair and the second light-based transmitter/receiver pair are located along different radial directions in relation to the rotational axis.

4. The rotary switch according to claim 1, wherein the first light-based transmitter/receiver pair is located substantially radially between the second light-based transmitter/receiver pair and the rotational axis.

5. The rotary switch according to claim 1, wherein the light screening element has a first screening wall that is concentric to the rotational axis of the rotary switch, wherein the first screening wall at least partially encircles the rotational axis and determines the transmission property of the first light transmission path of the first light-based transmitter/receiver pair, depending on the rotational position, wherein the light screening element additionally has a second screening wall that is concentric to the rotational axis of the rotary switch, wherein the second screening wall at least partially encircles the rotational axis, and is at a different distance to the rotational axis than a distance of the first screening wall to the rotational axis, and the transmission property of the second light transmission path of the second light-based transmitter/receiver pair, is determined based upon the rotational position.

6. The rotary switch according to claim 5, wherein at least one of the first or second screening walls has sections with different transmission properties, in particular wherein one or both of the first or second screening wall has alternating transparent sections and opaque sections, wherein the alternating transparent sections affect the transmission properties of the respective light transmission paths corresponding to different rotational positions.

7. The rotary switch according to claim 6, characterized in that the light screening element is configured to determine the transmission properties of the respective first and second light transmission paths in that the first and second screening walls block or open the light transmission paths based on the rotational position such that each rotational position can be identified based on a unique combination of opened or blocked light transmission paths.

8. The rotary switch according to claim 7, wherein each unique combination can be represented by a bit sequence, characterized in that a Hamming spacing between the respective bit sequences represent combinations has a value of at least 2.

9. The rotary switch according to claim 1, wherein the light-based transmitter is configured to transmit an infrared light signal, and wherein each of the first and second light-based receiver is configured to receiver the infrared light signal.

10. A device for selecting a gear setting in a motor vehicle of claim 1 further comprising.

Description

[0026] The invention shall be explained in greater detail below based on the attached drawings. Therein:

[0027] FIG. 1: shows a perspective view of an embodiment of a rotary switch according to the invention;

[0028] FIG. 2: shows a perspective view of the internal construction of the embodiment shown in FIG. 1;

[0029] FIG. 3a, b, c: show a top view of an embodiment of a rotary switch in a first, second, and third rotational position, and tables listing the respective rotational positions based on the respective receiver signals.

[0030] FIG. 1 shows a perspective view of an embodiment of a rotary switch 1 according to the invention. The rotary switch 1 has a knob 3. The knob 3 can be rotated to select a setting. The rotary switch 1 also has a housing 7. The housing 7 is composed of two parts 7a, 7b. Such rotary switches 1 are used in the automotive field, e.g. for adjusting the volume or to select a gear setting P, R, N, D.

[0031] FIG. 2 shows a perspective view of the internal construction of the rotary switch 1 shown in FIG. 1, wherein the first part of the housing 7a has been removed. A plastic component 11 extends from the middle of the rotary switch 1, along the rotational axis 9 of the rotary switch 1, which connects to the knob 3. Numerous rings 13a, b, c are located concentrically about the rotational axis 9. These rings 13a, b, c collectively form a light screening element 15. The respective rings 13a, b, c form screening walls, wherein each screening wall 13 has openings 17. These screening walls 13, or the light screening element 15, are rotated with the knob 3. As a result, either an opening 17 or an opaque section 19 of the screening wall 13a, b, c is positioned in a specific radial direction facing away from the rotational axis 9 of the light switch, comprised of the first 13a, second 13b and third 13c screening wall, respectively. The openings 17 allow light to pass, but the material of the screening wall 13 itself is opaque. There is also a printed circuit board 21, connected thereto with connecting pins 23. The printed circuit board 21 is electrically connected to a communication interface of the rotary switch 1, which is not shown therein, by means of contact pins 25.

[0032] There are also three transmitter/receiver pairs 5a, b, c. The transmitter/receiver pairs 5a, b, c are attached to, or located on, the undersurface of the printed circuit board 21. Each of the transmitter/receiver pairs 5a, b, c have one transmitter and one receiver, wherein the transmitters and receivers are each located opposite one another, such that a light transmission path 27 is formed between the transmitters and the receivers. The transmitter/receiver pairs are positioned such that the light transmission paths 27 each span one of the screening walls 13a, b, c. Depending on the rotational position, the light transmission paths 27 of the transmitter/receiver pairs 5 are either blocked or opened by the screening wall 13. By way of example, if a user rotates the knob 3 such that an opening is positioned between the transmitter and the receiver, the light transmission path 27 remains unobstructed, and a light signal from the transmitter is received by the receiver. A corresponding electrical signal is then conveyed to an evaluation unit by the printed circuit board 21. If an opaque section 19 of a screening wall 13 is positioned between the transmitter and the receiver in a specific rotational position, then no light reaches the receiver.

[0033] The transmitter/receiver pairs 5, or the light screening element 15 are configured such that for each specific rotational position, a unique combination of receiver signals are generated. These shall be explained in greater detail in reference to FIG. 3. The sub-FIGS. 3a, 3b, 3c each show different rotational positions D, N, R of one embodiment of a rotary switch 1. Only the light screening element 15 and the respective transmitter/receiver pairs 5 are shown therein. Tables are also shown in FIGS. 3a, 3b, and 3c. The tables 29 show the respective electrical signals for the first transmitter/receiver pair 5a in three different rotational positions D, N and R, which are generated by the receiver. A 1 is shown thereby when a light signal is received by the receiver, and a 0 is shown when no light signal is received. In this manner, it can be determined whether there is an opening 17 in the screening wall 13 or an opaque section 19 of the screening wall 13 is located between the transmitter and the receiver. The corresponding electrical signal values for the transmitter/receiver pairs 5b and 5c are given analogously.

[0034] A first rotational position D is shown in FIG. 3a. In the first rotational position D, an opening 17 of the first screening wall 13a is located between the first transmitter/receiver pair 5a, or in the light transmission path 2a of the first transmitter/receiver pair. The third transmitter/receiver pair 5c is located radially behind the first transmitter/receiver pair in relation to the rotational axis 9. The outermost screening wall 13c also has an opening 17, as is the case for the innermost screening wall 13a, such that a light signal from the third transmitter reaches the third receiver. A 1 is thus entered in the table 29. In this first rotational position D, an opaque section 19 of the middle screening wall 13b is positioned such that it interrupts the light transmission path 27b of the second transmitter/receiver pair 5b. Consequently, a 0 is entered in the table 29 at this point. The second transmitter/receiver pair 5b is radially offset to the first transmitter/receiver pair 5a. The transmitter/receiver pairs 5a, b, c are thus compactly grouped on one side of the rotary switch 1. As a result, the printed circuit board 21 only has to cover this subsection of the rotary switch 1.

[0035] In FIG. 3b, the first transmitter/receiver pair 5a is blocked by the innermost screening wall 13a. The second transmitter/receiver pair 5b is unobstructed, in contrast, such that a light signal from the second transmitter will reach the second receiver. Consequently, a 1 is entered in the table at this point. In the third pair 5c, it is likewise the case that there is no opening 19 in the light transmission path 27c, such that for the third transmitter/receiver pair 5c, a 1 is also entered for the second rotational position N. The transmitter/receiver pairs 5 and the light screening element 15 are configured such that a unique combination of unobstructed or blocked light transmission paths 27 are obtained for each rotational position D, N, R.

[0036] A table 29 such as that shown in FIGS. 3a, b, c can be stored in a data storage unit in an evaluation unit of the rotary switch. When the rotational positions D, N, R of the rotary switch 1 are detected, the signals generated by the transmitter/receiver pairs 5 can thus be formed through a comparison with these stored tables. The rotational positions D, N, R are thus determined. In the third rotational position R, signals from the first and second transmitters 5a, b are allowed to pass, and the third transmitter/receiver pair 5c is blocked. The combination of received signals generated in this manner can be regarded as bit sequences. It is thus possible to analyze bit sequences representing a Hamming spacing between the respective rotational positions D, N, R. In this embodiment of a rotary switch 1, the Hamming spacing between the bit sequences representing different rotational positions is always 2. It is conceivable to provide more transmitter/receiver pairs 5, in order to obtain greater Hamming spacings. It is also conceivable to use more screening walls 13, or to use screening walls 13 that have not only transparent 17 or opaque 19 sections, but also only allow specific light frequencies to pass through them, and thus increase the possible number of combinations, and thus obtain a greater Hamming spacing between the individual rotational positions D, N, R. As a result, the reliability of a rotary switch 1 can be increased, in particular for use as a gear setting selection switch.

REFERENCE SYMBOLS

[0037] 1 rotary switch [0038] 3 rotational position detection device [0039] 5a, b, c first, second, third transmitter/receiver pairs [0040] 7a, b first, second housing parts [0041] 9 rotational axis [0042] 11 plastic component [0043] 13a, b, c first, second, third screening walls [0044] 15 light screening element [0045] 17 opening [0046] 19 opaque section [0047] 21 printed circuit board [0048] 23 fastening pin [0049] 25 contact pin [0050] 27 light transmission path [0051] 29 table [0052] D, R, N rotational positions