Liquid crystal system and lighting device for vehicle

Abstract

The invention relates to a liquid crystal system comprising: at least one liquid crystal element comprising a front electrode having a front control contact and a rear electrode having a rear control contact; and control electronics, which are designed to apply a front-side control voltage to the front-side control contact of the respective liquid crystal element and to apply a rear-side control voltage to the rear-side control contact of the respective liquid crystal element in order to control the at least one liquid crystal element, the at least one liquid crystal element has a front side test contact on a front side electrode and a rear side test contact on a rear side electrode. The control electronics are configured to measure a front-side test voltage present at the front-side test contact and to compare it with a front-side control voltage of the respective liquid crystal element and to measure a rear-side test voltage present at the rear-side test contact and to compare it with a rear-side control voltage of the respective liquid crystal element. The invention also relates to a lighting device for a vehicle, comprising at least one liquid crystal system according to the invention.

Description

Technical Field

[0001] This invention relates to a liquid crystal system comprising: at least one liquid crystal element including a front electrode having a front control contact and a rear electrode having a rear control contact; and control electronics configured to control the at least one liquid crystal element by applying a front control voltage to the front control contact of the corresponding liquid crystal element and applying a rear control voltage to the rear control contact of the corresponding liquid crystal element. The invention also relates to a lighting device for a vehicle comprising at least one such liquid crystal system. Background Technology

[0002] The type of liquid crystal system described at the beginning is also known as an LC system and is used in various fields, such as as a so-called LC display for showing information or as so-called smart glass with electrically switchable light transmittance. Increasingly, such liquid crystal systems are also being used in safety-related applications, such as in vehicle lighting systems. Summary of the Invention

[0003] In view of this background, the objective of this invention is to realize fault identification in a liquid crystal system of the type described at the beginning or in a lighting device for a vehicle of the type described at the beginning.

[0004] This task is accomplished according to the invention by a liquid crystal system having the features of claim 1 and a lighting device for a vehicle having the features of claim 6.

[0005] The liquid crystal system according to the invention includes at least one liquid crystal element constructed in a manner known in principle, having a front electrode and a rear electrode, with a liquid crystal layer disposed between them. Preferably, both electrodes are transparent and each comprises a glass substrate coated with a conductive coating. The front electrode has a front control contact through which a front control voltage can be applied to the front electrode, and the rear electrode has a rear control contact through which a rear control voltage can be applied to the rear electrode. In principle, it is also conceivable that the front electrode and / or the rear electrode have multiple control contacts. Preferably, the liquid crystal system according to the invention includes multiple individually operable liquid crystal elements. Here, it is conceivable that the multiple liquid crystal elements each include a front electrode with a front control contact and a rear electrode with a rear control contact, or it is conceivable that the multiple liquid crystal elements have a common front electrode or a common rear electrode. For example, in so-called smart glass, multiple liquid crystal elements typically have a common large-area rear electrode.

[0006] The liquid crystal system according to the invention also includes control electronics configured in a manner known in principle for controlling the at least one liquid crystal element, i.e., selectively switching it to be transparent or opaque. Specifically, the control electronics are electrically connected to the front and rear control contacts of the at least one liquid crystal element and configured to control the at least one liquid crystal element by applying a suitable front control voltage to the front control contact of the respective liquid crystal element and a suitable rear control voltage to the rear control contact of the respective liquid crystal element. Typically, the control electronics are configured here to control the front and rear electrodes in opposite phases, i.e., applying a positive front control voltage at the front control contact and a negative rear control voltage at the rear control contact, or vice versa, such that a rectangular alternating voltage exists between the two electrodes. It is also conceivable that the front or rear control voltage is not negative during one phase, but approximately equal to zero. Preferably, the control electronics are implemented as an integrated circuit. The control electronics can be arranged separately from the at least one liquid crystal element on a separate circuit board and electrically connected to the at least one liquid crystal element via a connecting cable or other suitable connection means. However, the control electronics can also be arranged on a glass substrate of a liquid crystal element, in which case the control electronics are preferably implemented using a so-called chip-on-glass-Bauweise method.

[0007] According to the present invention, at least one liquid crystal element includes a front test contact at a front electrode and a rear test contact at a rear electrode, wherein the test contacts are preferably arranged as far away as possible from the control contacts of the corresponding electrodes. The front and rear test contacts of the at least one liquid crystal element are electrically connected to control electronics, wherein the control electronics are configured according to the present invention to measure a front test voltage present at the front test contact and compare it with a front control voltage of the corresponding liquid crystal element, and to measure a rear test voltage present at the rear test contact and compare it with a rear control voltage of the corresponding liquid crystal element. Under normal circumstances, control voltages should be applied to both electrodes via the control contacts, respectively, across the entire electrode and therefore also at the corresponding test contacts, such that under normal circumstances, the front test voltage should always be substantially equal to the front control voltage and the rear test voltage should always be substantially equal to the rear control voltage. Conversely, if at least one of the two test voltages deviates significantly from the corresponding control voltage, this is a clear indicator of a defect in the corresponding liquid crystal element and / or the leads of the corresponding liquid crystal element.

[0008] Therefore, reliable fault identification can be achieved in a relatively simple manner by using the test contacts according to the invention and comparing the test voltage with the control voltage according to the invention.

[0009] In a preferred embodiment, the front control contacts and front test contacts are arranged on opposite sides of the respective front electrodes, and the rear control contacts and rear test contacts are arranged on opposite sides of the respective rear electrodes, such that defects can be detected in a relatively large area of ​​the respective electrodes by comparing the test voltage present at the test contact with the corresponding control voltage. In the case of rectangular electrodes, the control contacts and test contacts are preferably arranged at opposite corners of the respective electrodes.

[0010] Preferably, at least one liquid crystal element has at least one additional front-side test contact at the front electrode and / or at least one additional rear-side test contact at the rear electrode, and the control electronics are configured to measure an additional front-side test voltage present at the at least one additional front-side test contact and compare it with the front-side control voltage of the corresponding liquid crystal element and / or measure an additional rear-side test voltage present at the at least one additional rear-side test contact and compare it with the rear-side control voltage of the corresponding liquid crystal element. By providing the at least one additional test contact, defects can be detected in a particularly large area of ​​the corresponding electrode, thereby enabling particularly reliable fault identification. Preferably, the control contact, test contact, and at least one additional test contact are arranged as far apart from each other as possible at the corresponding electrode, for example, at the corner of a rectangular electrode.

[0011] In a preferred embodiment of the liquid crystal system according to the present invention, each liquid crystal element has a front test contact and a rear test contact, so that the presence of defects can be detected for each liquid crystal element.

[0012] However, especially when the number of liquid crystal elements is large, it may be desirable to monitor only individual, particularly relevant liquid crystal elements, such that in an alternative preferred embodiment of the liquid crystal system according to the invention, at least one liquid crystal element is provided that does not have a front test contact and / or a rear test contact. For example, among multiple liquid crystal elements having a common rear electrode, only the front electrode of an individual liquid crystal element may have a front test contact.

[0013] The lighting device for a vehicle according to the present invention includes at least one of the liquid crystal systems described above according to the present invention. Here, the lighting device according to the present invention can, in principle, be any lighting device for any vehicle, such as headlights, taillights, or body lighting devices for motor vehicles or trailers.

[0014] Since the lighting device according to the invention includes at least one liquid crystal system according to the invention, reliable fault identification can be achieved in a relatively simple manner for the reasons described above. Attached Figure Description

[0015] Embodiments of the present invention will now be described with reference to the accompanying drawings. Herein:

[0016] Figure 1 A schematic diagram of a first lighting device for a vehicle according to the invention, having a first liquid crystal system according to the invention, is shown.

[0017] Figure 2 A schematic diagram of a second lighting device for a vehicle according to the invention, having a second liquid crystal system according to the invention, is shown.

[0018] Figure 3 A schematic diagram of a third lighting device for a vehicle according to the invention, having a third liquid crystal system according to the invention, is shown.

[0019] Figure 4 A schematic diagram of a fourth lighting device for a vehicle according to the invention, having a fourth liquid crystal system according to the invention, is shown. Detailed Implementation

[0020] Figure 1 A lighting device 200 for a vehicle (not shown) according to the present invention is shown.

[0021] The lighting device 200 includes a liquid crystal system 100 according to the invention, which has three identical liquid crystal elements 1 and a control electronics 2, wherein, for clarity, only one of the liquid crystal elements 1 is fully provided with reference numerals.

[0022] The liquid crystal element 1 includes a front electrode 3, which has a front control contact 4 and a front test contact 5, wherein the front control contact 4 and the front test contact 5 are arranged at opposite corners of the front electrode 3.

[0023] The liquid crystal element 1 also includes a rear electrode 6, which has a rear control contact 7 and a rear test contact 8, wherein the rear control contact 7 and the rear test contact 8 are arranged at opposite corners of the rear electrode 6.

[0024] The control electronics 2 is configured to control the liquid crystal element 1 by applying a front control voltage U.VA to the front control contact 4 of the corresponding liquid crystal element 1 and applying a rear control voltage U.RA to the rear control contact 7 of the corresponding liquid crystal element 1.

[0025] The control electronics 2 is also configured to measure the front test voltage U.VP present at the front test contact 5 of the liquid crystal element 1 and compare it with the front control voltage U.VA of the corresponding liquid crystal element 1, and to measure the rear test voltage U.RP present at the rear test contact 8 and compare it with the rear control voltage U.RA of the corresponding liquid crystal element 1.

[0026] Figure 2Another lighting device 200-1 according to the invention is shown, wherein, for features known to be the same as or similar to those of lighting device 200, the following are used: Figure 1 The corresponding figure labels in the diagram.

[0027] The lighting device 200-1 differs from the lighting device 200 in that the lighting device 200-1 includes an alternative liquid crystal system 100-1 according to the present invention, wherein the liquid crystal system 100-1 differs from the liquid crystal system 100 in that it is provided with a liquid crystal element 1-1 having a front control contact 4 and a rear control contact 7 for operation by the control electronics 2, but without a front test contact 5 and a rear test contact 8.

[0028] Figure 3 Another lighting device 200-2 according to the invention is shown, wherein, for features known to be the same as or similar to those of lighting device 200 or lighting device 200-1, the following is used: Figure 1 or Figure 2 The corresponding figure labels in the diagram.

[0029] The lighting device 200-2 differs from the lighting device 200-1 in that the lighting device 200-2 includes an alternative liquid crystal system 100-2 according to the present invention, wherein the liquid crystal system 100-2 differs from the liquid crystal system 100-1 in that, unlike the liquid crystal elements 1, 1-1 of the liquid crystal system 100-1, the liquid crystal elements 1-2, 1-3 of the liquid crystal system 100-2 have a common rear electrode 6.

[0030] Figure 4 Another lighting device 200-3 according to the invention is shown, wherein, for features that are the same as or similar to those known to lighting device 200, lighting device 200-1 or lighting device 200-2, the following methods are used: Figure 1 , Figure 2 or Figure 3 The corresponding figure labels in the diagram.

[0031] The lighting device 200-3 differs from the lighting device 200 in that the lighting device 200-3 includes an alternative liquid crystal system 100-3 according to the present invention, wherein the liquid crystal system 100-3 differs from the liquid crystal system 100 in that it is provided with only a single liquid crystal element 1-4.

[0032] The difference between the liquid crystal element 1-4 and the liquid crystal element 1 of the liquid crystal system 100 is that the front electrode 3 has two additional front test contacts 9 and 10, which are arranged at the two corners of the front electrode 3 that are not occupied by the front control contact 4 and the front test contact 5.

[0033] The difference between liquid crystal element 1-4 and liquid crystal element 1 of liquid crystal system 100 is that the rear electrode 6 has two additional rear test contacts 11 and 12, which are arranged at the two corners of the rear electrode 6 that are not occupied by the rear control contact 7 and the rear test contact 8.

[0034] The control electronics 2 is configured to additionally measure additional front-side test voltages U.VP2 and U.VP3 present at the other two front-side test contacts 9 and 10 and compare them with the front-side control voltage U.VA of the liquid crystal elements 1-4, respectively, and to measure additional rear-side test voltages U.RP2 and U.RP3 present at the other rear-side test contacts 11 and 12 and compare them with the rear-side control voltage U.RA of the liquid crystal elements 1-4, respectively.

[0035] List of reference numerals

[0036] 200; 200-1; 200-2; 200-3 lighting device

[0037] 100; 100-1; 100-2; 100-3 LCD system

[0038] 1; 1-1; 1-2; 1-3; 1-4 Liquid crystal elements

[0039] 2. Controlling electronic devices

[0040] 3 front electrodes

[0041] 4 front control contacts

[0042] 5 front test contacts

[0043] 6 Rear Electrode

[0044] 7 Rear control contacts

[0045] 8 Rear Test Contacts

[0046] 9, 10 Other front-side test contacts

[0047] 11, 12 Additional rear test contacts

[0048] U.RA rear control voltage

[0049] U.RP rear side test voltage

[0050] Additional rear-side test voltages for U.RP2 and U.RP3

[0051] U.VA Front Control Voltage

[0052] U.VP Front Side Test Voltage

[0053] Additional front-side test voltages for U.VP2 and U.VP3

Claims

1. LCD system (100; 100-1; 100-2; 100-3), including: At least one liquid crystal element (1; 1-1; 1-2; 1-3; 1-4), said at least one liquid crystal element comprising a front electrode (3) having a front control contact (4) and a rear electrode (6) having a rear control contact (7); and The control electronics (2) are configured to control at least one liquid crystal element (1; 1-1; 1-2; 1-3; 1-4) by applying a front control voltage (U.VA) to the front control contact (4) of the corresponding liquid crystal element (1; 1-1; 1-2; 1-3; 1-4) and applying a rear control voltage (U.RA) to the rear control contact (7) of the corresponding liquid crystal element (1; 1-1; 1-2; 1-3; 1-4). In this embodiment, at least one liquid crystal element (1; 1-2; 1-4) has a front test contact (5) at the front electrode (3) and a rear test contact (8) at the rear electrode (6), and The control electronics (2) are configured to measure the front test voltage (U.VP) present at the front test contact (5) and compare the front test voltage with the front control voltage (U.VA) of the corresponding liquid crystal element (1; 1-2; 1-4), and to measure the rear test voltage (U.RP) present at the rear test contact (8) and compare the rear test voltage with the rear control voltage (U.RA) of the corresponding liquid crystal element (1; 1-2; 1-4).

2. The liquid crystal system (100; 100-1; 100-2; 100-3) according to claim 1, wherein, The front control contact (4) and the front test contact (5) are arranged on opposite sides of the corresponding front electrode (3), and the rear control contact (7) and the rear test contact (8) are arranged on opposite sides of the corresponding rear electrode (6).

3. The liquid crystal system (100-3) according to any one of the preceding claims, wherein, At least one liquid crystal element (1-4) has at least one additional front test contact (9, 10) at the front electrode (3) and / or at least one additional rear test contact (11, 12) at the rear electrode (6), wherein the control electronics (2) is configured to measure additional front test voltages (U.VP2, U.VP3) present at the at least one additional front test contact (9, 10) and compare the additional front test voltages with the front control voltage (U.VA) of the corresponding liquid crystal element (1-4) and / or measure additional rear test voltages (U.RP2, U.RP3) present at the at least one additional rear test contact (11, 12) and compare the additional rear test voltages with the rear control voltage (U.RA) of the corresponding liquid crystal element (1-4).

4. The liquid crystal system (100; 100-3) according to any one of the preceding claims, wherein, Each liquid crystal element (1; 1-4) has a front test contact (5) and a rear test contact (8).

5. The liquid crystal system (100-1; 100-2) according to any one of claims 1 to 3, wherein, At least one liquid crystal element (1-1; 1-3) is provided that does not have a front test contact (5) and / or does not have a rear test contact (8).

6. A lighting device (200; 200-1; 200-2; 200-3) for a vehicle, comprising at least one liquid crystal system (100; 100-1; 100-2; 100-3) according to any one of the preceding claims.

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