Automotive lighting unit with OLED light source and related operating method

Abstract

The present invention provides an automotive lighting unit with an OLED light source and a related operating method. An automotive lighting unit (1) comprises: a lighting device equipped with one or more OLED light sources (6); and an electronic device (12) for determining a fault condition of the OLED light source (8). The electronic device (12) is used to determine a leakage resistance (Rp) of the OLED light source (8), and to determine the fault condition of the OLED light source (6) based on the leakage resistance (Rp).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority from European Patent Application No. 19166369.9 filed on March 29, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The invention relates to an automotive lighting unit provided with an OLED (Organic Light Emitting Diode) light source, an OLED electronic lighting device which can preferably be installed in an automotive lighting unit, and an operating method for the automotive lighting unit.

[0004] In more detail, the present invention relates to a lighting unit that can be installed in a car or a motor vehicle or any similar motorized vehicle, and this type of lighting unit preferably but not necessarily includes: a housing that is constructed to be recessed into a bay formed in the body of the vehicle; a front lens body that is at least partially made of transparent or translucent material and can be coupled to the housing at an opening in the housing; and an OLED electronic lighting device that is suitable for being accommodated in the housing. Background Art

[0005] The use of OLED light sources in the latest generation of automotive lighting units is known. OLED light sources make it easy to obtain homogeneous lighting surfaces with which new graphic effects and localized light geometries can be dynamically generated, thereby realizing multiple lighting functions using the same lighting unit.

[0006] However, in the case of the above-mentioned automotive lighting units with OLED light sources, there is still a need to be able to determine / detect a fault / breakage condition of the OLED light source. Summary of the Invention

[0007] It is therefore an object of the present invention to produce an automotive lighting unit which meets this requirement.

[0008] This object is achieved by the present invention in that it relates to a vehicle lighting unit comprising a lighting device provided with one or more OLED light sources, characterised in that the vehicle lighting unit comprises an electronic device which is configured in such a way that: a resistance of the OLED light source indicative of a leakage resistance of an equivalent circuit of the OLED light source is determined; and a fault condition of the lighting unit / OLED light source is determined based on the resistance indicative of the leakage resistance.

[0009] Preferably, the OLED light source comprises one or more light emitting regions; and the electronic device is configured to determine a dead zone state of at least one of the light emitting regions based on the resistance indicative of the leakage resistance.

[0010] Preferably, the OLED light source has a multi-pixel light-emitting OLED module, which includes multiple independent light-emitting areas, each of which is associated with a pixel; the electronic device is used to determine the existence of a dead zone state of at least one of the light-emitting areas associated with the pixel based on the resistance indicating the leakage resistance.

[0011] Advantageously, the electronic device is configured to determine a number of the light emitting areas in the dead zone state indicating corresponding dead pixels based on the resistance indicative of the leakage resistance.

[0012] The OLED light source preferably has a segmented OLED light-emitting module comprising a plurality of light-emitting areas, each of the plurality of light-emitting areas being associated with an OLED segment; the electronic device being configured to determine the presence of a dead-band state for at least one of the OLED segments based on the resistance indicative of the leakage resistance.

[0013] Preferably, the electronic device is configured to determine the number of the light emitting areas in the dead zone state indicative of a corresponding OLED dead segment based on the resistance indicative of the leakage resistance.

[0014] Preferably, the electronic device is configured to: provide a linearly increasing current ramp to the OLED light source until a built-in voltage is reached across the OLED light source; repeatedly measure the voltage across the OLED light source during the current ramp; determine a current / voltage characteristic curve during the current ramp based on the measured voltage; determine a slope of the current / voltage characteristic curve; and determine the resistance indicative of the leakage resistance based on the slope.

[0015] Preferably, the leakage resistance does not correspond to an impedance measured across the OLED light source.

[0016] Preferably, the linearly increasing current ramp provided to the OLED light source is not an alternating current (AC).

[0017] Preferably, the linearly increasing current ramp provided to the OLED light source is a direct current.

[0018] The present invention relates to an operating method for a vehicle lighting unit comprising a lighting device provided with one or more OLED light sources, characterized in that the method comprises the following steps: determining a resistance of the OLED light source indicating a leakage resistance of an equivalent circuit of the OLED light source; and determining a fault condition of the lighting unit / OLED light source based on the resistance indicating the leakage resistance.

[0019] Preferably, the OLED light source comprises one or more light emitting areas, and the method comprises the step of determining a dead zone state of at least one of the light emitting areas based on the resistance indicative of the leakage resistance.

[0020] Preferably, the OLED light source has a multi-pixel light-emitting OLED module, which includes a plurality of light-emitting areas, each of which is associated with a pixel; the method includes a step of determining the presence of a dead zone state of at least one of the light-emitting areas associated with the pixel based on the resistance indicating the leakage resistance.

[0021] Preferably, the method comprises the step of determining the number of the light emitting areas in the dead zone state, indicating corresponding dead pixels, based on the resistance indicative of the leakage resistance.

[0022] The OLED light source preferably has a segmented OLED light emitting module comprising a plurality of light emitting areas, each light emitting area of ​​the plurality of light emitting areas being associated with an OLED segment, the method comprising the step of determining the presence of a dead zone state for at least one of the OLED segments based on the resistance indicative of the leakage resistance.

[0023] Preferably, the method comprises the step of determining the number of said light emitting areas in said dead-zone state, indicative of corresponding OLED dead segments, based on said resistance indicative of said leakage resistance.

[0024] Preferably, the method comprises the following steps:

[0025] providing a linearly increasing current ramp to the OLED light source until a built-in voltage is reached across the OLED light source; repeatedly measuring a voltage across the OLED light source during the current ramp; determining a current / voltage characteristic curve during the current ramp based on the measured voltage; determining a slope of the current / voltage characteristic curve; and determining the resistance indicative of the leakage resistance based on the slope.

[0026] The invention further relates to a vehicle lighting device provided with one or more OLED light sources, comprising an electronic device for determining a resistance of the OLED light source indicating a leakage resistance of an equivalent circuit of the OLED light source; and determining a fault condition of the lighting unit / OLED light source based on the resistance indicating the leakage resistance.

[0027] Preferably, the OLED light source of the vehicle lighting device comprises one or more light emitting areas; and the electronic device is configured to determine a dead zone state of at least one of the light emitting areas based on the resistance indicative of the leakage resistance.

[0028] Preferably, the OLED light source of the vehicle lighting device has a multi-pixel light-emitting OLED module, which includes a plurality of independent light-emitting areas, each of which is associated with a pixel; the electronic device is used to determine the existence of a dead zone state of at least one of the light-emitting areas associated with the pixel based on the resistance indicating the leakage resistance.

[0029] Preferably, the electronic device of the vehicle lighting device is configured to determine the number of the light emitting areas in the dead zone state indicating corresponding dead pixels based on the resistance indicating the leakage resistance.

[0030] The OLED light source of the vehicle lighting device preferably has a segmented OLED light-emitting module, which includes a plurality of light-emitting areas, each light-emitting area of ​​the plurality of light-emitting areas being associated with an OLED segment; the electronic device is used to determine the presence of a dead-band state for at least one of the OLED segments based on the resistance indicative of the leakage resistance.

[0031] Preferably, the electronic device of the vehicle lighting device is configured to determine the number of the light emitting areas in the dead zone state indicative of corresponding OLED dead segments based on the resistance indicative of the leakage resistance.

[0032] Preferably, the electronic device of the vehicle lighting equipment is configured to: provide a linearly increasing current ramp to the OLED light source until a built-in voltage is reached across the OLED light source; repeatedly measure the voltage across the OLED light source during the current ramp; determine a current / voltage characteristic curve during the current ramp based on the measured voltage; determine a slope of the current / voltage characteristic curve; and determine the resistance indicative of the leakage resistance based on the slope.

[0033] Preferably, the leakage resistance of the equivalent circuit of the OLED light source of the vehicle lighting device does not correspond to an impedance measured across the OLED source.

[0034] Preferably, the linearly increasing current ramp provided to the OLED light source of the vehicle lighting device is not an alternating current (AC).

[0035] Preferably, the linearly increasing current ramp provided to the OLED light source of the vehicle lighting device is a direct current. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will now be described with reference to the accompanying drawings, which show non-limiting embodiments of the invention, in which:

[0037] Figure 1 is an exploded view of an example of an embodiment of an automotive lighting unit made in accordance with the teachings of the present invention;

[0038] Figure 2 Is set in Figure 1 A circuit diagram showing an example of an embodiment of an electronic control circuit and an electronic diagnostic circuit in an automotive lighting unit is shown;

[0039] Figure 3 A circuit model of eleven elements equivalent to an OLED light source is shown, which is provided with a leakage resistor;

[0040] Figure 4 is a graph showing current / voltage trends in three operating regions of an OLED light source;

[0041] Figure 5 A conventional circuit model of three elements equivalent to an OLED light source is shown;

[0042] Figure 6 Is set in Figure 2 A circuit diagram of an example of an embodiment of an electronic measuring device of an electronic diagnostic circuit in an automotive lighting unit is shown;

[0043] Figure 7 schematically illustrates a series of light emitting areas of a segmented OLED light source in an on-state in the absence of a fault condition;

[0044] Figure 8 Schematically shows the situation where a fault condition exists in the four black areas on the left. Figure 7 The luminous area shown;

[0045] Figure 9 schematically illustrates a series of light emitting areas of a multi-pixel OLED light source in an on-state in the absence of a fault condition;

[0046] Figure 10 Schematically shows the presence of a fault condition in the black area shown on an enlarged scale Figure 9 The luminous area shown is the black area that represents the pixel size area. DETAILED DESCRIPTION

[0047] The present invention will now be described in detail with reference to the accompanying drawings to enable those skilled in the art to make and use the invention. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles described may be applied to other embodiments and applications without departing from the scope of the invention as defined in the appended claims. Therefore, the present invention should not be considered limited to the embodiments described and shown, but should be given the widest scope consistent with the principles and features described and claimed herein.

[0048] Reference Figure 1 , reference numeral 1 schematically shows as a whole an exploded view of an automotive lighting unit manufactured according to an example of an embodiment of the present invention.

[0049] The automotive lighting unit 1 may preferably but not necessarily comprise a shaped rear housing 2, which is preferably but not necessarily cup-shaped. The rear housing 2 may, for example, be configured such that it may preferably but not necessarily be recessed into a bay, for example, in a vehicle body (not shown).

[0050] according to Figure 1 In the example shown, the automotive lighting unit 1 may further preferably include a front lens 3, which is, for example, at least partially made of a transparent or translucent material. The front lens 3 may be configured so that it can be coupled to the rear housing 2. The front lens 3 may preferably be arranged at an opening in the rear housing 2, such that the front lens 3 is preferably at least partially exposed from the vehicle body (not shown).

[0051] according to Figure 1 In the preferred embodiment shown, the vehicle lighting unit 1 further comprises a lighting device 4 .

[0052] The lighting device 4 may include an OLED lighting circuit 5. The OLED lighting circuit 5 may include one or more OLED light sources 8 (ie, OLEDs) provided with one or more light emitting areas 6.

[0053] according to Figure 7 and Figure 8 In the possible embodiment shown, the light-emitting area 6 comprises at least one OLED light source 8, ie at least one OLED having a so-called “segmented” OLED light-emitting structure.

[0054] exist Figure 8 and Figure 9 Each OLED segment shown in FIG is separated from the other OLED segments and corresponds to an OLED light emitting area 6. A “segmented” OLED light emitting structure may have a circuit configuration with a single cathode (common cathode) and multiple independent anodes, through which a complete and uniform on or off state of each OLED segment (i.e., the entire OLED light emitting area 6) may be selectively controlled.

[0055] As an example, in Figure 8 In the figure, the four OLED light-emitting areas 6 shown in black are in a "dead state" described in detail below. The dead state of the OLED segment corresponds to a so-called "OLED dead segment." It should be noted that according to this embodiment, the OLED light-emitting areas 6, i.e., the OLED segments, can have dimensions of the order of tens of centimeters.

[0056] according to Figure 9 and Figure 10 In the different embodiments shown, the OLED light emitting area 6 is included in at least one OLED light source 8 (i.e., at least one OLED), which has a so-called "multi-pixel" OLED light emitting structure, wherein each OLED light emitting area 6 has a smaller size relative to the size of a "pixel" in a conventional OLED display (on the order of a few millimeters).

[0057] As an example, in Figure 10 In the figure, two small OLED light-emitting areas 6 with reduced dimensions corresponding to two pixels, shown in black, are in a "dead state" as described in detail below. The dead state of the two OLED light-emitting areas 6 of the so-called "multi-pixel" OLED light-emitting structure each corresponds to a so-called "dead pixel".

[0058] It should be understood that the present invention should not be considered as limited to the "segmented" OLED light-emitting structure and / or "multi-pixel" OLED light-emitting structure described above and to which explicit reference will be made in the following discussion, but can be applied to any similar OLED light-emitting structure, such as an OLED structure having multiple electrically independent OLEDs, i.e., including their respective anodes and electrodes.

[0059] Under a fault condition, the light-emitting area 6 of the OLED light source 8 can be operated in an ON state or an OFF state. In the ON state, the OLED light-emitting area 6 of the OLED light source 8 emits light in response to a pilot signal, and in the OFF state, the OLED light-emitting area 6 of the OLED light source 8 does not emit light in the absence of a pilot signal.

[0060] In a fault condition, the state of the light emitting area 6 of the OLED light source 8 may correspond to a “dead zone state.” In the dead zone state, the OLED light emitting area 6 of the OLED light source 8 remains off, i.e., it does not emit light even when a pilot signal is provided to it (the anode receives a turn-on voltage).

[0061] In order to increase the clarity and understanding of the present invention, Figure 8 For example, a "segmented" OLED light source 8 is shown, wherein six corresponding light-emitting areas 6 are shown in grey to indicate the switched-on state, while Figure 9 The same OLED light source 8 is shown, wherein the four light emitting areas 6 are shown in black to indicate a dead zone state.

[0062] In order to increase the clarity and understanding of the present invention, Figure 9 Instead, an example of a "multi-pixel" OLED light source 8 is shown, in which all light-emitting areas 6 are shown in grey to indicate an on state, while Figure 10 The same OLED light source 8 is shown, wherein the two light emitting areas 6 are shown in black to indicate a dead zone state of the two light emitting areas 6 .

[0063] The lighting device 4 may further include electronic devices 12 for controlling the one or more OLED light sources 8, selectively switching the one or more OLED light sources 8 between an on state and an off state.

[0064] According to the present invention, the electronic device 12 is further configured to determine a fault condition of the lighting device 4 when it detects the presence of a dead zone condition in one or more light emitting areas 6 of the OLED light source 8 .

[0065] according to Figure 2 In the possible embodiment shown, the electronic device 12 may include, for example, an electronic control circuit 14 and an electronic diagnostic circuit 10, wherein the electronic control circuit 14 is designed to selectively control the OLED light source 8 and the electronic diagnostic circuit 10 is designed to detect / determine the above-mentioned fault condition of the light-emitting area 6 of the OLED light source 8.

[0066] Preferably, but not necessarily, such as Figure 1 As shown in the example of FIG, the control circuitry 14 of the electronic device 12 and the electronic diagnostic circuitry 10 may both be arranged on a single common PCB.

[0067] However, it should be understood that the control circuit 14 and the electronic diagnostic circuit 10 of the electronic device 12 may be arranged in separate respective electronic PCB boards, or in the same electronic board on which the OLED lighting circuit 5 is mounted.

[0068] according to Figure 1In the example of the preferred embodiment shown, the lighting device 4 can be conveniently arranged in the automotive lighting unit 1 so that it directly or indirectly faces the front lens body 3 to perform a lighting function and / or any vehicle light signaling function on the exterior of the vehicle (not shown).

[0069] It should be understood that in the following description, the term "automotive lighting unit" should be understood as follows: a headlight, a taillight, at least one exterior marker / position light, at least one direction indicator (usually indicated by an arrow), at least one brake light / brake light (usually with a stop indication), at least one fog light, at least one reversing light, at least one low beam light, at least one high beam light or any other type of light that can be installed in a similar motor vehicle (preferably a motor vehicle).

[0070] according to Figure 1 In the preferred embodiment shown, the lighting device 4 may preferably, but not necessarily, be housed in the vehicle lighting unit 1 , for example, in the rear housing 2 .

[0071] However, it should be understood that the present invention is not limited to the electronic lighting device 4 being disposed within the vehicle lighting unit 1. In particular, the electronic lighting device 4 may be disposed within and / or integrated into other parts of the vehicle. For example, the electronic lighting device 4 may be disposed on the rear window and / or disposed within / on the vehicle body / chassis.

[0072] according to Figure 1 In the preferred embodiment shown, the OLED light source 8 of the OLED lighting circuit 5 can be controlled by the electronic control circuit 14 based on one or more control signals provided by a central control unit 100 (e.g., an electronic control unit) installed in the vehicle, so as to be selectively switchable between an ON state and an OFF state. It should be understood that the central control unit 100 can be included in the automotive lighting unit 1.

[0073] according to Figure 2 In the preferred embodiment shown, the electronic control circuit 14 may be configured to receive a signal from the electronic diagnostic circuit 10 indicating a fault condition due to the presence of a dead zone condition in one or more light emitting regions 6 of the OLED light source 8 .

[0074] The electronic control circuit 14 may also be used to communicate with the central control unit 100 to provide thereto a signal indicative of at least a fault condition indicating a deadband condition in one or more light emitting regions 6 of the OLED light source 8 .

[0075] The electronic control circuit 14 may be connected to the central control unit 100 via at least one communication bus (not shown) to receive control signals, and may further be provided with control terminals to provide pilot signals to selectively control one or more OLED light sources 8 .

[0076] The pilot signal generated by the electronic control circuit 14 can switch the OLED light source 8 to an ON state or an OFF state.

[0077] It should be understood that the pilot signal provided by the electronic control circuit 14 may also cause adjustment of a control electrical quantity (e.g., current or voltage) of the OLED light source 8 so as to determine a corresponding modulation and / or change of one or more lighting parameters (e.g., light intensity and / or color) of the OLED light source 8.

[0078] It should be understood that other embodiments of the electronic device 12 are possible.

[0079] For example, the electronic device 12 may include a static configuration register (not shown) containing a predefined control / command configuration indicating the current value to be applied to the OLED light source 8 .

[0080] This register may in turn be contained in a memory mounted in the same electronic board (not shown) housing the control circuit 14 .

[0081] Regarding the electronic diagnostic circuit 10, it can be configured to communicate unidirectionally and / or bidirectionally with the electronic control circuit 14 and / or the central control unit 100. The central control unit 100 can be configured to provide the aforementioned control signals based on one or more data / electrical signals indicative of a fault condition of the OLED light source 8 detected by the electronic device 12.

[0082] according to Figure 2 and Figure 3 In the preferred embodiment shown, the electronic device 12 can be used to determine / measure the leakage resistance Rp (described in detail below) of the OLED light source 8 and determine a fault condition based on the determined / measured leakage resistance Rp. The leakage resistance Rp corresponds to the resistance of the equivalent OLED circuit through which the leakage current flows.

[0083] The fault condition may indicate a failure of the lighting unit 1 and / or a failure of the lighting device 4 and / or a failure of the OLED light source 8 .

[0084] The applicant has found that the circuit / model of the OLED light source 8 ( Figure 3 The value of the leakage resistance Rp (shown) indicates a fault condition of the OLED light source 8 of the lighting device 4 of the lighting unit 1.

[0085] A fault condition of the OLED light source 8 that can be detected based on the leakage resistance Rp also indicates a dead zone state of at least one light emitting area 6 of the OLED light source 8 .

[0086] In the embodiment where the OLED light source 8 is segmented ( Figure 7 and Figure 8), the fault condition detectable based on the leakage resistor Rp indicates the presence of a dead zone state of the light emitting area 6 of at least one of the OLED segments (ie, the OLED dead segment) in the OLED segment of the light source 8 itself.

[0087] In embodiments where the OLED light source 8 has a multi-pixel OLED circuit structure / architecture, a fault condition detectable based on the leakage resistance Rp advantageously indicates the presence of a dead zone state in the light emitting region 6 of at least one pixel (i.e., a dead pixel) of the LED light source 8.

[0088] Figure 3 An equivalent circuit model of the OLED of the OLED light source 8 is shown, which is useful for understanding the meaning of the leakage resistance Rp. The OLED equivalent circuit comprises eleven elements and is different from the simplified equivalent circuit model having three elements.

[0089] The operation of the equivalent circuit with eleven elements is Figure 4 , and provides a division of the voltage-current characteristic of the OLED 8 into three different operating regions I, II, III.

[0090] Reference Figure 3 and Figure 4 , the equivalent circuit includes:

[0091] a resistor connected between the anode terminal A and the node N, the resistor having a resistance Re indicative of the resistance of the associated OLED electrode in the OLED light source 8;

[0092] a first electrical branch connected between the node A and the cathode terminal C, along which are connected in series an ideal diode D1, a resistor with a built-in resistance Rbi and a voltage generator Vbi representing the built-in voltage of the OLED light source 8;

[0093] a second electrical branch connected between the node N and the cathode terminal C, along which the ideal diode D2, a resistor with a resistance Rs and a voltage generator Vo representing the threshold voltage of the OLED light source 8 required for a substantial current to flow through the OLED;

[0094] Diode D3, which is connected between the anodes of the two ideal diodes D1 and D2,

[0095] a capacitor connected in parallel with a resistor of resistance Rbi and having a diffusion capacitance Cd representing the capacitance of the OLED depending on the voltage, frequency and material of the cathode;

[0096] a capacitor having a geometric capacitance Cg associated with the form factor of the OLED connected between the node N and the cathode C,

[0097] A resistor having a leakage resistance Rp is connected in parallel with the geometric capacitance capacitor Cg, and a leakage current Ip flows through the resistor.

[0098] It should be noted that the leakage resistance Rp according to the present invention does not correspond to an OLED ( Figure 5 The total impedance (usually represented by Z) of a simplified equivalent three-element circuit (as shown).

[0099] Specifically, instead of the total impedance being measured between the anode terminal A and the cathode terminal C, Figure 3 The leakage resistance Rp of the equivalent circuit shown in does not depend on the frequency of the driving signal nor on the capacitances Cd and Cs of the equivalent circuit of the OLED.

[0100] It should also be noted that Applicants have discovered that, unlike the OLED impedance, the leakage resistance RP conveniently and specifically indicates the presence of an OLED light source failure caused by one or more OLED dead pixels or segments.

[0101] refer to Figure 2 In a possible example of an embodiment shown, the electronic diagnostic circuit 10 may include: an electronic measuring device 16 designed to measure the leakage resistance Rp of the OLED light source 8; preferably, but not necessarily, a memory device 18 designed to store at least one predetermined resistance threshold value indicating the absence of a fault condition of the OLED light source 8; and an electronic processing device 19 for determining a fault condition of the OLED light source 8 based on the leakage resistance Rp and the predetermined resistance threshold value. For example, a fault condition of the OLED light source 8 may be determined when the leakage resistance Rp satisfies a predetermined condition having a resistance threshold value.

[0102] For example, a fault condition of the OLED source 8 may be determined when the leakage resistance Rp is lower than and / or equal to a predetermined resistance threshold.

[0103] According to a possible embodiment, the memory device 18 may store a plurality of predetermined resistance thresholds indicating dead zone states in which the same number of light emitting areas 6 are present in the OLED light source 8 .

[0104] The applicant has in fact discovered that the leakage resistance Rp of the above-mentioned equivalent circuit also indicates the number of light-emitting areas 6 in the OLED light source 8 that are in the dead zone state.

[0105] The electronic processing device 19 may then determine the number of light emitting areas 6 present in the dead-zone state in the OLED light source 8 based on the predetermined Rp leakage resistance and the resistance threshold.

[0106] For example, when the leakage resistance Rp satisfies a predetermined condition having a resistance threshold associated with a predetermined number of light emitting areas 6 in the dead zone state, the electronic processing device 19 may determine that the predetermined number of light emitting areas 6 in the dead zone state exists.

[0107] It will be appreciated that the predetermined resistance threshold may be determined by laboratory tests performed on the OLED light source 8, during which the leakage resistance Rp is determined / calculated / measured using light emitting areas 6 in a dead zone state and / or when the number of light emitting areas 6 in a dead zone state is varied.

[0108] The applicant has found that as the number of light emitting areas 6 in the dead zone state of the OLED light source 8 increases, the leakage resistance Rp of the OLED light source 8 decreases.

[0109] It will be appreciated that in addition to or as an alternative to using a predetermined resistance threshold, the electronic processing device 19 may determine the fault condition and / or in particular the number of light emitting areas 6 in a deadband state by means of predetermined diagnostic functions.

[0110] For example, the electronic processing device 19 may implement a mathematical function and / or a calculation algorithm to provide the number of light emitting areas 6 of the OLED light source 8 that are in the dead zone state based on the calculated / determined leakage resistance Rp.

[0111] For example, Figure 6 There is shown a possible embodiment of the electronic measuring device 16. In the shown example, the electronic measuring device 16 comprises a current generating stage 20, an amplifying stage 21 (eg an operational amplifier), a transistor 22, a resistor 23, a voltage measuring stage 24 and a processing stage 25 to determine the leakage resistance Rp.

[0112] The current generating stage 20 , the amplifying stage 21 and the transistor 22 may be connected to each other and to the OLED light source 8 so as to operate as a current source supplying / providing an increasing current ramp to the OLED light source 8 .

[0113] It will be appreciated that the increasing current ramp provided to the OLED light source 8 does not correspond to a time variation of the alternating current signal, ie the alternating current signal AC, which is important for calculating the Figure 5 It may be necessary to calculate the total impedance of the equivalent circuit in the three-element model shown in . Instead, the increasing current ramp may include an increasing straight line and a linearly increasing current ramp.

[0114] A voltage measurement stage 24 may be connected to the OLED light source 8, for example to the cathode and anode, to measure / sample the voltage at predetermined intervals during the provision of the increasing current ramp.

[0115] When the measured voltage VOLED(t) reaches a predetermined voltage threshold indicating the end of the first operating region I of the OLED ( Figure 4 ), the voltage measurement stage 24 can also cooperate with the current generation stage 20 to interrupt the increasing straight and linear current ramp.

[0116] Preferably, the predetermined voltage threshold for terminating the first operating region I may correspond to a built-in voltage of the OLED light source 8 .

[0117] The processing stage 25 can be configured in the following manner: receiving the VOLED(t) voltage value measured by the voltage measurement stage 24; determining the VOLED(t) voltage value based on the current slope provided; Figure 4 The substantially linear and straight current / voltage growth characteristic or curve / function I(V) in the first operating region I is schematically shown in FIG.

[0118] The processing stage 25 may be used to determine a value indicative of a slope m (angle factor) of the linear growth curve / function I(V) in the first region I, and to determine the leakage resistance Rp from the determined slope m.

[0119] For example, the processing stage 25 may determine the leakage resistance Rp by taking the inverse of the slope m, ie, Rp=1 / m.

[0120] As described above, the electronic device 12 can therefore conveniently transmit the fault condition of the OLED light source 8 to the central control unit 100 .

[0121] The electronic device 12 may also conveniently transmit to the central control unit 100 an indication that a dead zone condition exists in one or more light emitting regions 8 of the OLED light source 8 .

[0122] The electronic device 12 can also conveniently transmit to the central control unit 100 the number of light-emitting areas 6 where the OLED light source 8 is in the dead zone state.

[0123] The electronic control circuit 14 and / or the central control unit 100 can be used to perform control operations of the lighting unit 1 and / or the LED light source 6 based on the fault condition and / or the lighting area 6 in the dead zone state and / or the number of lighting areas 6 in the dead zone state.

[0124] The control operations may include, for example: switching off the OLED light source 8 based on the number of light emitting areas 6 that are in a dead zone state; and / or providing information (warning) to a user indicating a fault state of the lighting unit; and / or providing information to a user indicating a fault state of the OLED light source 8 (e.g. an OLED segment exhibiting a fault); and / or storing fault data in a memory for further processing and / or all other processing related to fault management.

[0125] The operating method of the lighting unit may include the following steps: determining / calculating / measuring a leakage resistance Rp associated with an OLED equivalent circuit of the OLED light source 8; and determining a fault condition of the OLED light source 8 based on the leakage resistance Rp.

[0126] The operating method of the lighting unit includes transmitting information about the fault condition of the OLED light source 8 and / or the lighting area 6 in the dead zone state and / or the number of lighting areas 6 in the dead zone state to the control unit 100 .

[0127] Preferably, the method further includes the step of turning off the OLED light source 8 based on the number of light emitting areas 6 in the dead zone state. Preferably, the method further includes the steps of: feeding a linearly increasing current ramp to the OLED light source 8, preferably until a built-in voltage is reached across the OLED light source 8; repeatedly measuring a VOLED(t) voltage across the OLED light source 8 during the supply of the increasing current ramp to the OLED light source 8; determining a current / voltage characteristic curve I(V) that changes with time during the supply of the current ramp based on the measured voltage VOLED(t); determining a value m indicating a slope / angle coefficient of the current / voltage characteristic curve I(V); and calculating a leakage resistance Rp based on the determined value m.

[0128] The benefits of the above-described lighting unit are as follows.

[0129] The system makes it possible to detect fault conditions of OLED light sources by a solution that is simple and therefore economical to implement. Detecting dead pixels and / or dead OLED segments in a lighting unit is also advantageous from a photometric point of view, since it identifies current sinking conditions that can significantly reduce the light emission from the lighting unit, with the risk of this emission being reduced below the value indicated by the regulations.

[0130] Finally, it is clear that the automotive lighting unit, the method of operating said lighting unit and the lighting device described and explained above may be subject to modifications and variations without departing from the scope of the present invention.

Claims

1. A vehicle lighting unit (1), comprising a lighting device (4) provided with one or more OLED light sources (8), wherein the OLED light sources (8) comprise one or more light-emitting areas (6), It is characterized in that The vehicle lighting unit (1) comprises an electronic device (12), wherein the electronic device (12) is used for: - determining the resistance of the OLED light source (8) indicating the leakage resistance (Rp) of the equivalent circuit of the OLED light source (8); - determining a fault condition based on said resistance being indicative of said leakage resistance (Rp), - determining a dead zone state of at least one of the light emitting areas (6) based on the resistance indicative of the leakage resistance (Rp).

2. The automotive lighting unit according to claim 1, wherein: The one or more OLED light sources (8) have a multi-pixel light emitting OLED structure comprising the one or more light emitting regions (6) that are independent of each other, each of the plurality of light emitting regions (6) being associated with a pixel, The electronic device (12) is used to determine the presence of a dead zone state indicating dead pixels of one or more light emitting regions (6) based on the resistance indicating the leakage resistance (Rp).

3. The automotive lighting unit according to claim 2, wherein: The electronic device (12) is used to determine the number of the light emitting areas (6) in the dead zone state indicating the corresponding number of dead pixels based on the resistance indicating the leakage resistance (Rp).

4. The automotive lighting unit according to claim 1, wherein: At least one or more of the OLED light sources (8) have a segmented OLED light emitting structure comprising a plurality of light emitting regions (6), each of the plurality of light emitting regions (6) being associated with an OLED segment, The electronic device (12) is used to determine the existence of a dead-band state for at least one of the OLED segments based on the resistance indicative of the leakage resistance (Rp).

5. The automotive lighting unit according to claim 4, wherein: The electronic device (12) is used to determine the number of the light emitting areas (6) in the dead zone state indicative of the number of corresponding OLED dead segments based on the resistance indicative of the leakage resistance (Rp).

6. The automotive lighting unit according to claim 1, wherein: The electronic device (12) is used for: - providing a linearly increasing current ramp to the one or more OLED light sources (8) until a built-in voltage is reached across the one or more OLED light sources (8), - repeatedly measuring the voltage (VOLED(t)) across said one or more OLED light sources (8) during the provision of said current ramp, - determining a current / voltage characteristic (I(V)) during said current ramp based on the measured voltage (VOLED(t)), - determining the slope (m) of said current / voltage characteristic curve (I(V)), - determining a resistance indicative of said leakage resistance (Rp) based on said slope (m).

7. A method for operating a vehicle lighting unit, the vehicle lighting unit comprising a lighting device (4) provided with one or more OLED light sources (8), wherein the OLED light sources (8) comprise one or more light-emitting areas (6), It is characterized in that The operation method comprises the following steps: - determining the resistance of the OLED light source (8) indicating the leakage resistance (Rp) of the equivalent circuit of the OLED light source (8); - determining a fault condition based on said resistance being indicative of said leakage resistance (Rp), and - determining a dead zone state of at least one of the light emitting areas (6) based on the resistance indicative of the leakage resistance (Rp).

8. The method according to claim 7, wherein: The one or more OLED light sources (8) have a multi-pixel light emitting OLED module comprising one or more light emitting areas (6), each of the one or more light emitting areas (6) being associated with a pixel, The method comprises the step of determining the presence of a dead zone state for at least one of the one or more light emitting regions (6) associated with a pixel based on the resistance indicative of the leakage resistance (Rp).

9. The method according to claim 8, wherein: The method comprises the steps of determining the number of the light emitting areas (6) in the dead zone state indicating the number of corresponding dead pixels based on the resistance indicating the leakage resistance (Rp).

10. The method according to claim 7, wherein: The OLED light source (8) has a segmented OLED light emitting module, which includes a plurality of light emitting areas (6), each of which is associated with an OLED segment. The method comprises the step of determining the presence of a dead-band state for at least one of the OLED segments based on the resistance being indicative of the leakage resistance (Rp).

11. The method according to claim 10, wherein: The method comprises the steps of determining the number of the light emitting areas (6) in the dead zone state, indicating the corresponding OLED dead segment, based on the resistance indicating the leakage resistance (Rp).

12. The method according to any one of claims 8 to 11, wherein: The method comprises the following steps: - providing a linearly increasing current ramp to the one or more OLED light sources (8) until a built-in voltage is reached across the OLED light sources (8), - repeatedly measuring the voltage (VOLED(t)) across said one or more OLED light sources (8) during said current ramp, - determining a current / voltage characteristic (I(V)) during said current ramp based on the measured voltage (VOLED(t)), - determining the slope (m) of said current / voltage characteristic curve (I(V)), - determining a resistance indicative of said leakage resistance (Rp) based on said slope (m).

13. A vehicle lighting device (4) provided with one or more OLED light sources (8), wherein the OLED light source (8) comprises one or more light emitting areas (6), It is characterized in that The vehicle lighting device (4) comprises an electronic device (12), which is configured in the following manner: - determining the resistance of the OLED light source (8) indicating the leakage resistance (Rp) of the equivalent circuit of the OLED light source (8); - determining a fault condition of the lighting unit / OLED light source (8) based on said resistance being indicative of said leakage resistance (Rp), - determining a dead zone state of at least one of the light emitting areas (6) based on the resistance indicative of the leakage resistance (Rp).

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