Vehicle lamp system, power supply circuit

Abstract

The present application relates to a vehicle lamp system, a power supply circuit. An array-type light emitting device (212) includes a plurality of pixel circuits (PIX) electrically connected in parallel and arranged in an array in space. A power supply circuit (220) supplies power to the array-type light emitting device (212). A DC / DC converter (224) is outputted via a power supply line connected to a power supply terminal of the array-type light emitting device (212). A power supply control circuit (225) controls the DC / DC converter (224) in such a manner that an object voltage (V CNT ) approaches a target value (V CNT（REF） ) set in accordance with a light distribution pattern. CNT（REF） ​

Description

Technical Field

[0001] This invention relates to vehicle lighting fixtures. Background Technology

[0002] Vehicle lights typically switch between low beam and high beam. Low beam provides illumination to the vicinity of the vehicle at a specified illuminance, with a beam pattern determined to avoid glare for oncoming or following vehicles. It is primarily used for urban driving. High beam, on the other hand, provides relatively higher illuminance to illuminate a wider area ahead and further into the distance. It is primarily used for high-speed driving on roads with less oncoming or following traffic. Therefore, high beam offers better visibility for the driver compared to low beam, but it can cause glare to drivers of vehicles ahead or pedestrians.

[0003] In recent years, an ADB (Adaptive Driving Beam) scheme has been proposed, which dynamically and adaptively controls the beam pattern of high beams based on the surrounding conditions of the vehicle. ADB technology detects the presence of vehicles in front, oncoming vehicles, or pedestrians, and reduces or turns off the lights in the corresponding areas to reduce glare for vehicles or pedestrians.

[0004] As an ADB lamp, the bypass structure combining LED (light-emitting diode) strings and bypass circuits has been put into practical use. Figure 1 This is a block diagram of light 1R in bypass mode.

[0005] The ADB lamp 1R includes an LED string (LED strip) 50, a constant current driver 70, and a bypass circuit 80. The LED string 50 includes multiple LEDs 52_1 to 52_n (n ≥ 2) connected in series. The ADB lamp 1R is configured such that the beams emitted by each of the multiple LEDs 52_1 to 52_n illuminate different areas on an imaginary vertical screen 40 in front of the vehicle.

[0006] The constant current driver 70 includes a current source 72 that generates a drive current I that is stabilized to a specified current amount. LED The circuit supplies power to the LED string 50. The bypass circuit 80 includes multiple switches SW1 to SWn connected in parallel with the multiple LEDs 52_1 to 52_n.

[0007] With one switch SWi (1≦i≦n) of the bypass circuit 80 off, the current I generated by the current source 72... LED The current flows through LED52_i, thus LED52_i lights up. With switch SWi on, the current I generated by current source 72... LED The current flows around to switch SWi, thus turning off LED52_i.

[0008] On the imaginary vertical screen 40, a light distribution pattern 42 is formed that corresponds to the on and off states of multiple bypass switches SW1 to SWn.

[0009] exist Figure 1 In bypass lamps, the number of LEDs (n), i.e., the number of sections that can be controlled to be on or off, ranges from a few to about a dozen. To achieve a greater number of sections, an ADB lamp using an LED (light-emitting diode) array has been proposed. Figure 2 This is a block diagram of an ADB lamp 1S using an LED array. The ADB lamp 1S includes an LED array device 10, a light distribution controller 20, and a power supply circuit 30. The LED array device 10 includes multiple LEDs 12 arranged in an array and an LED driver 14 that drives the multiple LEDs 12. It is a device packaged as a single unit (called an array-type light-emitting device). A pixel (also called a pixel circuit) consists of LEDs 12 and an LED driver 14. The LED driver 14 includes a current source (switch) connected in series with the LEDs 12. By controlling the conduction and cutoff of the current source, the conduction (lighting on) and cutoff (lighting off) of each pixel are switched.

[0010] The power supply circuit 30 supplies power voltage V to the LED array device 10. DD The power supply circuit 30 includes a DC / DC converter 32 and its controller 34. The output voltage V of the DC / DC converter 32 is... OUT Feedback voltage V FB The feedback is sent to controller 34 as feedback voltage V FB Approaching the target value V REF In this way, the DC / DC converter 32 is controlled.

[0011] The light distribution controller 20 generates control signals for turning on and off multiple specified pixels and sends them to the LED array device 10. The emitted light beam from the LED array device 10 is irradiated onto an imaginary vertical screen 40 via an optical system (not shown). A light distribution pattern 42 corresponding to the on / off states of the multiple light-emitting elements 12 is formed on the imaginary vertical screen 40.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 2018-172038 Summary of the Invention

[0015] The technical problem that the invention aims to solve

[0016] Topic 1. The inventor of this invention addresses... Figure 2 We conducted research on the ADB lamp 1S and ultimately identified the following technical issues.

[0017] exist Figure 2 In the circuit, multiple (N) pixel circuits are connected in parallel, therefore the output current I of the power supply circuit 30 is... OUT The maximum is I OUT（MAX） =I LED ×N. Currently, LED array devices with several thousand to over 10,000 pixels N are under development.

[0018] For example, let's call it I. LED =10mA, with N=3000 LEDs, what is the maximum output current I of power supply circuit 30? OUT（MAX） Arrive at 30A.

[0019] The power cable 16 or connector has a DC resistive component R, which will generate a voltage drop V due to the large current flowing through it. DROP (=R×I) OUT Set the voltage at the output terminal of power supply circuit 30 to V. OUT At that time, the power supply voltage (also known as the load input voltage) supplied to the power supply terminals of the LED array device 10 is V. DD for

[0020] V DD =V OUT -R×I OUT .

[0021] For the pixel circuit to function properly, the load input voltage V DD It must be greater than V DD（MIN） =Vf + V SAT +α. Vf is the forward voltage of the LED, V SAT α is the voltage between the two terminals of LED driver 14 (minimum operating voltage), and α is the voltage margin.

[0022] Therefore, in the power supply circuit 30, it is necessary to output voltage V. OUT Target voltage V OUT（REF） satisfy

[0023] V OUT（REF） >V DD（MIN） +R×I OUT

[0024] The controller 34 is designed in this way.

[0025] Figure 3 (a) and (b) are Figure 2 The waveform diagram of the ADB lamp 1S operation. Output current I. OUT In 0~I OUT（MAX） The range of variation. Assume the maximum output current I. OUT（MAX） to satisfy

[0026] V OUT（REF） =V DD（MIN） +R×I OUT（MAX）

[0027] The method for determining the output voltage V OUT Target value V OUT（REF） In this case, in I OUT When the voltage is ≒0, the load input voltage V DD Comparison of minimum voltage V DD（MIN） Larger. (V) DD -V DD（MIN） )×I OUT This is wasted electricity consumption. If the target value V is set relatively low... OUT（REF） Then the load input voltage V DD Below the minimum operating voltage V DD（MIN） The likelihood of this increasing can cause the light to flicker or go out.

[0028] In addition, such as Figure 3 As shown in (a) at time t0, when the output current I OUT When there is a rapid change, if there is a response delay in the controller 34, the output voltage V will... OUT Decrease, power supply voltage V DD Decrease. Power supply voltage V DD Below the minimum operating voltage V DD（MIN） At that time, flickering will occur.

[0029] Topic 2. The minimum operating voltage V of commercially available LED array devices 10 according to the standard specifications. DD（MIN） Minimum operating voltage V DD（MIN） Based on the lowest operating voltage of the pixel, specifically, based on the forward voltage V of LED12. F With the voltage drop V of the current source D sum.

[0030] The minimum operating voltage for each pixel varies from pixel to pixel within the same chip of the LED array device 10, and thus varies from individual LED array device 10. Furthermore, the minimum operating voltage V... DD（MIN） It is also affected by temperature. Typically, according to the standard specified value V... DD（SPEC） Taking into account individual differences or temperature variations in the LED array devices 10, a margin will be added, compared to the minimum operating voltage V. DD（MIN） The true value is more definitively determined. Therefore, based on the value V specified in the standard... DD（SPEC） When designing the operating conditions of the power supply circuit 30, for most LED array devices 10 used in practice, an excessive voltage will be supplied, which will lead to increased power consumption.

[0031] One aspect of this disclosure is derived in view of subject 1, one of the exemplary purposes of which is to provide a lighting system capable of stably supplying power to an array of light-emitting devices.

[0032] One aspect of this disclosure is derived in view of subject 1, one of the exemplary purposes of which is to provide a lighting system capable of reducing the power consumption of array-type light-emitting devices.

[0033] Methods for solving technical problems

[0034] 1. One aspect of this disclosure relates to a lighting system. The lighting system includes: an array of light-emitting devices, comprising a plurality of pixel circuits electrically connected in parallel and arranged in an array in space; and a power supply circuit for supplying power to the array of light-emitting devices. The power supply circuit includes: a DC / DC converter whose output is connected to the array of light-emitting devices via a power cable; and a power control circuit for controlling the DC / DC converter in a manner that controls the target voltage to approach the target value by setting a target value according to a light distribution pattern.

[0035] 2. One aspect of this disclosure relates to a lighting system. The lighting system includes: an array of light-emitting devices, comprising multiple pixel circuits electrically connected in parallel and arranged in a matrix in space; a power supply circuit supplying power to the array of light-emitting devices; and a connection unit including a power cable connecting the power supply circuit and the array of light-emitting devices. The power supply circuit includes: a DC / DC converter whose output is connected to the array of light-emitting devices via the power cable; and a power control circuit acquiring the voltage drop of the power cable, setting a target value based on the voltage drop of the power cable, and controlling the DC / DC converter such that the output voltage of the DC / DC converter is close to the target value.

[0036] 3. One aspect of this disclosure relates to a lighting system. The lighting system includes: a variable light source with adjustable light distribution, including an array of light-emitting devices; and a power supply circuit for supplying power to the array of light-emitting devices. The array of light-emitting devices has multiple pixel circuits. The multiple pixel circuits are electrically connected in parallel, arranged in an array in space, and each includes a light-emitting element and a current source connected in series. The array of light-emitting devices is configured to acquire data related to the voltage drop of the multiple light-emitting elements included in the multiple pixel circuits and transmit it to an external source. The power supply circuit includes: a DC / DC converter whose output is connected to the array of light-emitting devices via a power cable; and a power control circuit that controls the target voltage to approach a target value corresponding to the data, thereby controlling the DC / DC converter.

[0037] Furthermore, any combination of the above-mentioned constituent elements, or any scheme in which the constituent elements of this disclosure are interchangeable or transformed between methods, apparatuses, systems, etc., are also valid as solutions of this disclosure.

[0038] Invention Effects

[0039] According to one aspect of this disclosure, power consumption can be reduced. According to one aspect of this disclosure, power can be stably supplied to an array-type light-emitting device. Attached Figure Description

[0040] Figure 1 This is a block diagram of a bypass mode light.

[0041] Figure 2 This is a block diagram of an ADB lamp in LED array mode.

[0042] Figure 3 (a) and (b) are Figure 2 The waveform diagram of the ADB light's operation.

[0043] Figure 4 This is a block diagram of the lighting system according to Embodiment 1.

[0044] Figure 5 It is shown Figure 4 The diagram shows the operation of the control system of the lighting system in Example 1.

[0045] Figure 6 It is shown Figure 4 The diagram shows the operation of the control system for the lighting system in Example 2.

[0046] Figure 7 (a) and (b) illustrate the application of forward voltage V. F A graph showing the control of the target value.

[0047] Figure 8 This is a diagram illustrating the operation of the lighting system.

[0048] Figure 9 This is a block diagram of the headlight in Example 1.1.

[0049] Figure 10 yes Figure 9 The waveform diagram of the headlight operation.

[0050] Figure 11 This is a circuit diagram showing an example of the structure of a feedback circuit.

[0051] Figure 12 This is a circuit diagram showing an example of the structure of a voltage setting circuit.

[0052] Figure 13 This is a block diagram of the headlight in Example 1.2.

[0053] Figure 14 The waveform diagram shows the operation of the headlights in Control Example 2.

[0054] Figure 15 The waveform diagram shows the operation of the headlights in Example 4.

[0055] Figure 16 This is a block diagram of the headlight in Example 1.3.

[0056] Figure 17 This is a functional block diagram of the feedback circuit.

[0057] Figure 18 This is the circuit diagram of the headlight in Example 1.4.

[0058] Figure 19 This is a diagram showing the headlight of variant 1.1.

[0059] Figure 20 This is a diagram showing the headlight of variant 1.2.

[0060] Figure 21 This is a block diagram of the lighting system according to embodiment 2.

[0061] Figure 22 This is an explanation Figure 21 A diagram illustrating the operation of the lighting system.

[0062] Figure 23 This is a block diagram of the headlight in Embodiment 2.1.

[0063] Figure 24 This is a circuit diagram showing an example of the structure of a feedback circuit.

[0064] Figure 25 This is a block diagram of the headlight in Example 2.2.

[0065] Figure 26 This is a block diagram of the headlight in Example 2.3.

[0066] Figure 27 This is a block diagram of the headlight in Example 2.4.

[0067] Figure 28 This is a diagram showing the headlight of variant 2.1.

[0068] Figure 29 This is a diagram showing the headlight of variant 2.2.

[0069] Figure 30 This is a block diagram of the lighting system according to embodiment 3.

[0070] Figure 31 (a) and (b) are diagrams showing the operation of the lighting system.

[0071] Figure 32 This is a diagram illustrating the operation of the lighting system.

[0072] Figure 33 This is a block diagram of the headlight in Example 3.1.

[0073] Figure 34 yes Figure 33 The waveform diagram of the headlight operation.

[0074] Figure 35 This is a circuit diagram showing an example of the structure of a feedback circuit.

[0075] Figure 36 This is a circuit diagram showing an example of the structure of a voltage setting circuit.

[0076] Figure 37 This is a block diagram of the headlight in Example 3.2.

[0077] Figure 38 yes Figure 37 The waveform diagram of the headlight operation.

[0078] Figure 39 This is a block diagram of the headlight in Example 3.3.

[0079] Figure 40 This is a functional block diagram of the feedback circuit.

[0080] Figure 41 This is the circuit diagram of the headlight in Example 3.4.

[0081] Figure 42 This is a block diagram showing the structure of a microcontroller.

[0082] Figure 43 This is a diagram illustrating the calibration of the microcontroller's built-in A / D converter.

[0083] Figure 44 This is a diagram showing the headlight of variant 3.1.

[0084] Figure 45 This is a diagram showing the lighting system of variation 3.2. Detailed Implementation

[0085] This summary provides an overview of several exemplary embodiments of this disclosure. This summary serves as a preface to the detailed description that follows, and is intended to provide a basic understanding of the embodiments, briefly illustrating several concepts of one or more embodiments, and is not intended to limit the scope of the invention or disclosure. This summary is not a comprehensive overview of all conceivable embodiments, and is not intended to identify essential elements of all embodiments or to define the scope of some or all of the solutions. For convenience, "an embodiment" is sometimes used to refer to one or more embodiments (examples or variations) disclosed in this specification.

[0086] 1. A lighting system according to one embodiment includes: an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and arranged in a matrix in space; and a power supply circuit for supplying power to the array-type light-emitting device. The power supply circuit includes: a DC / DC converter whose output is connected to the array-type light-emitting device via a power cable; and a power control circuit for controlling the DC / DC converter in a manner that controls the target voltage to approach the target value by setting a target value according to a light distribution pattern.

[0087] The current flowing in an array-type light-emitting device varies according to the light distribution pattern. Therefore, by dynamically and adaptively changing the target value of the controlled object's voltage according to the light distribution pattern, it is possible to prevent the power supply voltage supplied to the array-type light-emitting device from falling below the minimum operating voltage. Furthermore, unnecessary power consumption can be reduced.

[0088] Alternatively, the power control circuit can change the target value before the light distribution pattern is changed.

[0089] The lighting system of one embodiment may further include a control unit that controls multiple pixel circuits according to a light distribution pattern. The power control circuit can set a target value based on first data related to the light distribution pattern received from the control unit.

[0090] In one embodiment, the power control circuit may include: a voltage setting circuit that generates a correction voltage corresponding to a light distribution pattern; a feedback circuit that generates a feedback voltage based on the controlled voltage and the correction voltage; and a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter such that the feedback voltage is close to a predetermined reference voltage. In cases where a converter controller is used that cannot externally set the internal reference voltage, the target value of the controlled voltage can be set by shifting the feedback voltage based on the correction voltage.

[0091] In one embodiment, the voltage setting circuit may include: a microcontroller that generates a digital setting value corresponding to the light distribution pattern; and a D / A converter that converts the setting value into an analog correction voltage. This enables software control of the target voltage value of the controlled object.

[0092] In one embodiment, the power control circuit may include: a voltage setting circuit that generates a reference signal corresponding to a light distribution pattern; and a converter controller having a feedback pin for receiving a feedback voltage corresponding to the voltage of the controlled object, and a reference voltage setting pin for receiving the reference signal, thereby controlling the DC / DC converter such that the feedback voltage is close to the reference voltage based on the reference signal. When using a converter controller capable of externally controlling the internal reference voltage, the target value of the controlled object voltage can be set by directly controlling the internal reference voltage of the converter controller based on data.

[0093] In one embodiment, the voltage setting circuit may include a microcontroller that generates a set value corresponding to a digital pattern, with a reference voltage corresponding to the set value. This enables software control of the target voltage value.

[0094] In one embodiment, the power supply circuit may further include a detection terminal connected to the power supply terminal of the array-type light-emitting device via a detection line separate from the power cable. The controlled voltage may also be the detection voltage generated by the detection terminal. According to this structure, a feedback loop is formed to supply an appropriate power supply voltage to the power supply terminal of the array-type light-emitting device. Therefore, unnecessary power consumption can be reduced.

[0095] In one embodiment, the controlled voltage can also be the output voltage of the DC / DC converter. According to this structure, since a feedback loop is formed in such a way that the output voltage of the DC / DC converter is close to the target value, the required response speed of the DC / DC converter can be reduced.

[0096] An array-type light-emitting device can be configured to acquire and transmit second data related to the voltage drop of multiple light-emitting elements contained in multiple pixel circuits. In addition to the light distribution pattern, the power control circuit can also set a target value based on the second data. By monitoring the voltage drop of the light-emitting elements during actual operation, the minimum operating voltage of the array-type light-emitting device can be accurately estimated. Furthermore, by reflecting the voltage drop of the light-emitting elements in the feedback control of the power supply circuit in real time, power consumption can be reduced.

[0097] 2. A lighting system according to one embodiment includes: an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and arranged in an array in space; a power supply circuit for supplying power to the array-type light-emitting device; and a connection unit including a power cable connecting the power supply circuit and the array-type light-emitting device. The power supply circuit includes: a DC / DC converter whose output is connected to the array-type light-emitting device via the power cable; and a power control circuit for acquiring the voltage drop of the power cable, setting a target value based on the voltage drop of the power cable, and controlling the DC / DC converter such that the output voltage of the DC / DC converter is close to the target value.

[0098] By monitoring the voltage drop in the power cable and dynamically and adaptively adjusting the target value of the output voltage based on the voltage drop, it is possible to prevent the power supply voltage to the array-type light-emitting devices from falling below the minimum operating voltage. Furthermore, unnecessary power consumption can be reduced.

[0099] In one embodiment, the power cable may further include a power line connecting the positive output terminal of the DC / DC converter to the power supply terminal of the array-type light-emitting device. The power control circuit can acquire the voltage drop of the power line and set a target value based on the voltage drop of the power line.

[0100] In one embodiment, the power cable may include: a power line connecting the positive output terminal of the DC / DC converter and the power terminal of the array-type light-emitting device; and a ground line connecting the negative output terminal of the DC / DC converter and the ground terminal of the array-type light-emitting device. The power control circuit can acquire the voltage drop between the power line and the ground line, and set a target value based on the voltage drop between the power line and the ground line.

[0101] In one embodiment, the power supply circuit may further include a current sensor that generates a current detection signal corresponding to the output current of the DC / DC converter. The power supply control circuit may also set a target value based on the current detection signal.

[0102] In one embodiment, the power supply circuit may further include a detection terminal connected to the power terminal of the array-type light-emitting device via a detection line separate from the power cable. The power control circuit can obtain the voltage drop of the connection unit based on the difference between the output voltage of the DC / DC converter and the detection voltage of the detection terminal.

[0103] In one embodiment, the power control circuit may include: a feedback circuit that generates a feedback voltage based on the output voltage of the DC / DC converter and a correction voltage corresponding to the voltage drop of the connection unit; and a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter such that the feedback voltage is close to a specified reference voltage.

[0104] In one embodiment, the power control circuit may include: a voltage setting circuit that generates a reference signal corresponding to the voltage drop of the connection unit; and a converter controller having a feedback pin that receives a feedback voltage corresponding to the output voltage and a reference voltage setting pin that receives the reference signal, controlling the DC / DC converter such that the feedback voltage is close to a reference voltage based on the reference signal.

[0105] 3. A lighting system according to one embodiment includes: a variable light source with adjustable light distribution, including an array of light-emitting devices; and a power supply circuit for supplying power to the array of light-emitting devices. The array of light-emitting devices includes multiple pixel circuits. The multiple pixel circuits are electrically connected in parallel and arranged in a matrix in space, each including a light-emitting element and a current source connected in series. The array of light-emitting devices is configured to acquire data related to the voltage drop of the multiple light-emitting elements included in the multiple pixel circuits and transmit it to an external source. The power supply circuit includes: a DC / DC converter whose output is connected to the array of light-emitting devices via a power cable; and a power control circuit for controlling the DC / DC converter in a manner that controls the target voltage to approach a target value corresponding to the data.

[0106] By monitoring the voltage drop of the light-emitting elements during actual operation, the minimum operating voltage of the array-type light-emitting device can be accurately estimated. Furthermore, by reflecting the voltage drop of the light-emitting elements in the feedback control of the power supply circuit in real time, power consumption can be reduced.

[0107] In one embodiment, the target value may be based on the maximum value of the voltage drop of the plurality of light-emitting elements.

[0108] In one embodiment, the power control circuit may include: a voltage setting circuit that generates a correction voltage corresponding to the data; a feedback circuit that generates a feedback voltage based on the controlled voltage and the correction voltage; and a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter such that the feedback voltage is close to a predetermined reference voltage. In cases where a converter controller is used that cannot externally set the internal reference voltage, the target value of the controlled voltage can be set by shifting the feedback voltage according to the correction voltage.

[0109] In one embodiment, the voltage setting circuit may include: a microcontroller that generates a digital setpoint corresponding to the data; and a D / A converter that converts the setpoint into an analog correction voltage. This enables software control of the target voltage of the controlled object.

[0110] In one embodiment, the power control circuit may include: a voltage setting circuit that generates a setting signal corresponding to data; and a converter controller having a feedback pin for receiving a feedback voltage corresponding to the voltage of the controlled object, and a reference voltage setting pin for receiving the setting signal, thereby controlling the DC / DC converter such that the feedback voltage is close to a reference voltage based on the reference signal. In the case where a converter controller capable of controlling the internal reference voltage from the outside is used, the target value of the controlled object voltage can be set by directly controlling the internal reference voltage of the converter controller according to the data.

[0111] In one embodiment, the voltage setting circuit may include a microcontroller that generates a set value corresponding to the data. A reference voltage may also correspond to the set value. Thus, the target value of the controlled object's voltage can be controlled by software.

[0112] In one embodiment, the power supply circuit may further include a detection terminal connected to the power supply terminal of the array-type light-emitting device via a detection line separate from the power cable. The controlled voltage may be the detection voltage generated by the detection terminal. According to this structure, a feedback loop is formed to supply an appropriate power supply voltage to the power supply terminal of the array-type light-emitting device. Therefore, unnecessary power consumption can be reduced.

[0113] In one embodiment, the controlled voltage can be the output voltage of the DC / DC converter. According to this structure, a feedback loop is formed so that the output voltage of the DC / DC converter is close to the target value, thus reducing the required response speed of the DC / DC converter.

[0114] In one embodiment, the lighting system may further include a control unit connected to the interface circuit of the array-type light-emitting device, which controls the switching on and off of multiple pixel circuits of the array-type light-emitting device. The power control circuit may receive data via the control unit.

[0115] In one embodiment, the microcontroller can acquire the error between the controlled object voltage and the target value based on data. If the converter controller cannot detect a deviation of the controlled object voltage from the target value, the microcontroller can monitor the error between the controlled object voltage and the target value to detect abnormal conditions.

[0116] In one embodiment, the microcontroller can determine an anomaly when the error between the controlled object voltage and the target value exceeds a predetermined threshold.

[0117] In one embodiment, when the microcontroller determines an anomaly, the setpoint can be fixed at a predetermined value. By fixing the predetermined value to a higher level, a higher voltage is forcibly supplied to the array-type light-emitting device in the abnormal state, thereby maintaining the illumination.

[0118] In one implementation, the microcontroller can also store a history of data. Maintaining a log in electronic devices can be applied to fault analysis or new product development by suppliers of the electronic devices or manufacturers of devices incorporating them. In particular, the voltage drop of the light-emitting element is an important parameter indicating efficiency or temperature, making its retention as a log useful.

[0119] In one embodiment, the lighting system may also include a temperature sensor. The microcontroller can store information related to the temperature obtained by the temperature sensor.

[0120] (Implementation Method)

[0121] The preferred embodiments will now be described with reference to the accompanying drawings. The same or equivalent constituent elements, components, and processes shown in the various drawings are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. Furthermore, the embodiments are not intended to limit the invention but are illustrative, and not all features or combinations thereof described in the embodiments are essential parts of the invention.

[0122] In this specification, the term "the state of connection between component A and component B" includes the case where component A and component B are physically and directly connected, as well as the case where component A and component B are indirectly connected via other components that do not substantially affect their electrical connection state or impair the function or effect achieved through their coupling.

[0123] Similarly, the phrase "the state in which component C is positioned between component A and component B" means, in addition to the cases where component A and component C are directly connected, or component B and component C are directly connected, the cases where they are indirectly connected via other components without substantially affecting their electrical connection state or impairing the function or effect achieved through their coupling.

[0124] Furthermore, in this specification, electrical signals such as voltage signals and current signals, or the reference numerals used to mark circuit elements such as resistors and capacitors, indicate their respective voltage values, current values, or resistance values ​​and capacitance values ​​as needed.

[0125] (Implementation Method 1)

[0126] Figure 4 This is a block diagram of the lighting system 100 according to Embodiment 1. The lighting system 100 is an ADB lighting system, including a battery 102, a host controller 104, and a headlight 200.

[0127] The host controller 104 generates beam distribution instructions for the headlight 200. The beam distribution instructions may include a lighting command and additional information. The lighting command may include a signal indicating whether the high beam or low beam is on or off. Based on the lighting command, the basic beam distribution that the headlight 200 should form is determined. Furthermore, the additional information may include data related to the area where high beams should not be emitted (the shaded area), or information such as vehicle speed and steering angle. Based on the additional information, the basic beam distribution is corrected, and the final beam distribution is determined. The host controller 104 may be configured as a vehicle-side ECU or as an ECU built into the lamp-side of the headlight 200.

[0128] The headlight 200 is an ADB lamp that includes a variable light source 210, a power supply circuit 220, and a control unit 260.

[0129] The variable light source 210 includes multiple pixels arranged in an array, and each pixel can be individually controlled to be turned on or off. In the headlight 200, the on / off state of multiple pixels is controlled in a manner that achieves the desired light distribution.

[0130] More specifically, the variable light source 210 includes an array-type light-emitting device 212. The array-type light-emitting device 212 has n pixel circuits PIX1 to PIXn and a power supply terminal VDD connected to the multiple pixel circuits PIX1 to PIXn.

[0131] The pixel circuit PIXj (1≦j≦n) includes a light-emitting element 213_j and a current source 214_j connected in series between the power supply terminal VDD and the ground terminal (grounding wire) GND. The multiple light-emitting elements 213_1 to 213_n are semiconductor light-emitting elements such as LEDs, LDs (semiconductor lasers), and organic EL elements, and are arranged in an array (matrix) in space.

[0132] Multiple current sources 214_1 to 214_n can be individually controlled to be turned on and off. When the j-th current source 214_j is turned on, the corresponding light-emitting element 213_j emits light, and the pixel circuit PIXj is in the lit state.

[0133] The interface circuit 216 controls the current sources 214_1 to 214_n to turn on and off according to the control signal S2 from the control unit 260. The interface circuit 216 is connected to the control unit 260 via a high-speed serial interface and receives the control signal S2 indicating the on and off status of all pixels.

[0134] The power supply circuit 220 supplies power to the variable light source 210. The power supply circuit 220 includes a constant voltage output converter that supplies a stabilized power supply voltage V to the power supply terminal VDD of the array-type light-emitting device 212. DD Power supply voltage V DD According to V F +V SAT The typical setting is around 4-5V. F It is the forward voltage of the light-emitting element 213, V SAT This is the minimum operating voltage of the current source 214. Therefore, the power supply circuit 220 can be powered by a battery voltage of approximately 12V (or 24V). BAT It consists of a buck converter.

[0135] The control unit 260 receives the light distribution command S1 from the host controller 104, generates a control signal S2 corresponding to the light distribution command S1, and sends it to the variable light distribution light source 210. The control unit 260 can also be called a rendering ECU. For example, the control unit 260 performs PWM control on multiple pixel circuits PIX1 to PIXn of the array-type light-emitting device 212 to control the light distribution. The PWM frequency is several hundred Hz (e.g., 100–400 Hz), therefore the PWM period is several milliseconds to tens of milliseconds (ms).

[0136] Next, the structure of the power supply circuit 220 will be described. The power supply circuit 220 includes an output terminal AP / AN, a ground terminal GND, a DC / DC converter 224, and a power control circuit 225.

[0137] The output terminals AP / AN are connected to the power supply terminal VDD and ground terminal GND of the array-type light-emitting device 212 via power cable 204. Power cable 204 includes a power line LVDD and a ground line LGND. The positive output OUTP of the DC / DC converter 224 is connected to the power supply terminal VDD of the array-type light-emitting device 212 via output terminal AP and power line LVDD. The negative output OUTN of the DC / DC converter 224 is connected to the ground terminal GND of the array-type light-emitting device 212 via output terminal AN and ground line LGND. The input to the DC / DC converter 224 is supplied with a voltage V from the battery. BAT .

[0138] The power control circuit 225 sets the controlled object voltage V according to the light distribution pattern. CNT Target value V CNT（REF） To control the voltage V of the object CNT Approaching the target value V CNT（REF） The DC / DC converter 224 is controlled in this manner. For example, the power control circuit 225 receives data S4 containing information related to light distribution from the control unit 260.

[0139] Details will be described later, including the voltage V of the controlled object. CNT It can be the power supply voltage V of the array-type light-emitting device 212 DD It can also be the output voltage V of the DC / DC converter 224. OUT .

[0140] The above describes the structure of the lighting system 100. This disclosure serves as... Figure 4 The invention is not limited to any particular configuration, but rather to the block diagrams or circuit diagrams, or to the various devices and methods derived from the above description. The following description, not to narrow the scope of the invention, but to aid in understanding the nature or operation of the invention, or to clarify it, will provide more specific structural examples or embodiments.

[0141] Next, the operation of the lighting system 100 will be explained with reference to several control examples.

[0142] (Control Example 1)

[0143] Figure 5 It is shown Figure 4 The diagram illustrates the operation of control example 1 for the lighting system 100. In control example 1, the controlled object voltage V... CNT The power supply voltage V for the array-type light-emitting device 212 DD The power control circuit 225 controls the power supply voltage V according to the light distribution pattern. DD Target value V DD（REF） .

[0144] At time t1, the light distribution pattern changes from the first pattern PTN1 to the second pattern PTN2, and the current I of the second pattern PTN2... OUT2 The current I greater than the first pattern PTN1 OUT For example, the first pattern PTN1 is the urban mode light distribution, illuminating the low beam area. The second pattern PTN2 is the active mode light distribution; since it also illuminates the high beam area, the number of illuminated pixels is relatively higher, and the output current I... OUT It is also relatively large.

[0145] Under steady-state conditions, the power supply voltage V DD Target value V DD（REF） With minimum operating voltage V DD（MIN） Set to the same degree.

[0146] Before the change of the light distribution pattern PTN, the power control circuit 225, in other words, the current I... OUT The time t0 before the increase in timing causes the power supply voltage V to... DD Target value V DD（REF） Increase ΔV. Power supply voltage V DD Following the target value V DD（REF） The target value increases by an amount ΔV, which is determined by the power supply voltage V accompanying the current change. DD The magnitude of the voltage drop, which is a sharp peak, can be used to determine the target value V. DD（REF） The increased timing t0 can be supplied from the control unit 260.

[0147] At time t1, when switching the photodistribution pattern PTN, the current I... OUT This increases the power supply voltage V. As a result, the power supply control circuit 225 responds slowly, thus reducing the power supply voltage V. DD A transient decrease, compared to the target value V DD（REF） The error increases, and then it returns to the target value V. DD（REF） .

[0148] The power control circuit 225 makes the target value V at time t2. DD（REF） Return to the original voltage level. Follow the target value V. DD（REF） Power supply voltage V DD Reduce to the original voltage level.

[0149] Furthermore, in control example 1, the output voltage V of the DC / DC converter 224 OUT According to V OUT =V DD +V DROP And change. V DROP It is the voltage drop in the LVDD power supply line or connector, in volts (V). DROP =I OUT ×R represents.

[0150] The above describes the operation of Control Example 1. According to this control example, the power supply voltage V is adjusted before the change of the light distribution pattern. DD Target voltage V DD（REF） Increasing ΔV allows the power supply voltage V to be... DD Maintain above the minimum operating voltage V DD（MIN） This can prevent flickering.

[0151] (Control Example 2)

[0152] Figure 6 It is shown Figure 4 The diagram illustrates the operation of control example 2 for the lighting system 100. In control example 2, the controlled object voltage V... CNT It is the output voltage V of the DC / DC converter 224. OUT The power control circuit 225 controls the output voltage V according to the light distribution pattern. OUT Target value V OUT（REF） In control example 2, the power supply control circuit 225 responds very quickly, even if an output current I occurs. OUT The rapid change in voltage can also affect the output voltage V. OUT Maintain a certain level.

[0153] The power control circuit 225 determines the current I based on the light distribution pattern PTN#. OUT＃ Set the target value V OUT（REF） #. The target value for each light distribution pattern is represented by the following formula (A).

[0154] V OUT（REF）＃ =V DD（MIN） +R×I OUT＃ …(A)

[0155] The above describes the operation of control example 2. According to this control example, when the output voltage V... OUT Set as the voltage V of the controlled object CNT In the structure, by adjusting the output current I OUT Set the target value V OUT（REF） The power supply voltage V can be DD Maintain at the lowest operating voltage V DD（MIN） Nearby, unnecessary power consumption can be reduced.

[0156] (Control Example 3)

[0157] In Control Example 3, similarly to Control Example 2, the controlled object voltage V CNT It is the output voltage V of the DC / DC converter 224. OUT In Control Example 3, similarly to Control Example 2, the target value V is set according to equation (A). OUT（REF）Furthermore, in Control Example 3, similarly to Control Example 1, in the case of a switch in the light distribution pattern accompanied by a sharp change in current, the target value V is set beforehand. OUT（REF） Increase the specified voltage amplitude ΔV.

[0158] According to Control Example 3, flickering can be prevented when the response speed of the power supply control circuit 225 is slow.

[0159] (Control Example 4)

[0160] In Control Example 4, similarly to Control Example 2, the controlled object voltage V CNT It is the output voltage V of the DC / DC converter 224. OUT In control example 4, no target value V based on equation (A) was calculated. OUT（REF） The setting is the same as in Control Example 1. In the case of a switch in the light distribution pattern accompanied by a sharp change in current, the target value V is set beforehand. OUT（REF） Increase the specified voltage amplitude ΔV.

[0161] According to Control Example 4, flickering can be prevented when the response speed of the power supply control circuit 225 is slow.

[0162] (Control based on device information)

[0163] return Figure 4 The lighting system 100 may also have the following features.

[0164] The interface circuit 216 of the array-type light-emitting device 212 is configured to monitor the voltage drop (i.e., forward voltage) V of the light-emitting elements 213 of each of the multiple pixel circuits PIX1 to PIXn. F1 ~V Fn It can generate a voltage including the positive voltage V. F1 ~V Fn The relevant information data S3A. In this embodiment, this data S3A is sent to the power supply circuit 220 as data S3B via the control unit 260.

[0165] The power control circuit 225 reflects the data S3B in the controlled object voltage V. CNT Target value V CNT（REF） In the middle. Controlled object voltage V CNT Target value V CNT（REF） The forward voltage V of the light-emitting element 213 corresponding to all channels can be used. F1 ~V Fn The maximum value V F（MAX） For example, the data S3B received by the power control circuit 225 may include the positive voltage V of the light-emitting elements 213 of all channels. F1 ~VFn At this time, the power control circuit 225 can obtain a positive voltage V. F1 ~V Fn The maximum value V F（MAX） According to the maximum value V F（MAX） Generate target value V CNT（REF） Alternatively, the control unit 260 can acquire a positive voltage V. F1 ~V Fn The maximum value V F（MAX） This will contain the maximum value V F（MAX） The data S3B is sent to the power control circuit 225.

[0166] Figure 7 (a) and (b) illustrate the application of forward voltage V. F A graph showing the control of the target value. Figure 7 Images (a) and (b) show the operation of different individual components of the lighting system 100. Figure 7 In (a), the forward voltage V of the i-th pixel PIXi of the array-type light-emitting device 212 Fi The maximum value V F（MAX） Controlled object voltage V CNT That is, the power supply voltage V DD Target value V DD（REF） According to

[0167] V DD（REF） =V D +V Fi（MAX） +α

[0168] Confirmed. V D α is the voltage drop of current source 214, and α is the margin.

[0169] exist Figure 7 In (b), the positive voltage V of the j-th pixel PIXj of the array-type light-emitting device 212 is... Fj The maximum value V F（MAX） Controlled object voltage V CNT That is, the power supply voltage V DD Target value V DD（REF） according to

[0170] V DD（REF） =V D +V Fj +α

[0171] And that's confirmed.

[0172] like Figure 7 As shown in (a) and (b), the forward voltage V was measured for the actual product. F Determine the target value V DD（REF） This allows the power supply voltage V to be adjusted.DD Compared to the value V specified by the standard DD（SPEC） The power consumption of the array-type light-emitting device 212 can be reduced.

[0173] Figure 8 This is a diagram showing the operation of the lighting system 100. Figure 8 This illustrates the operation of a lighting system 100 under different temperature conditions. The forward voltage V of the LED is shown. F It exhibits temperature dependence, decreasing as temperature increases. According to this embodiment, the controlled object voltage V can be adaptively set based on temperature. DD Target value V DD（REF） Therefore, electricity consumption can be reduced.

[0174] The above is control based on device information. According to the lighting system 100, the voltage drop V contained in the data S3B is controlled... F Relevant information is reflected in the feedback control of the power supply circuit 220 in real time, thereby reducing power consumption. Specifically, this is achieved by monitoring the positive voltage V of the light-emitting element 213 during actual operation. F This allows for accurate estimation of the actual minimum operating voltage V of the array-type light-emitting device 212. DD（MIN） The minimum operating voltage V is estimated in this way. DD（MIN） This will reflect individual differences or temperature variations in the array-type light-emitting device 212, and may be lower than the value V specified in the standard. DD（SPEC） Therefore, based on the correct minimum operating voltage V DD（MIN） The operating conditions of the power supply circuit 220 are dynamically determined, thereby reducing the power supply voltage V supplied to the array-type light-emitting device 212. DD This can reduce electricity consumption.

[0175] Next, a specific structural example of the headlight 200 will be described. In the following text, details based on the forward voltage V will be omitted. F Explanation of the control of the target value of the relevant data S3.

[0176] (Example 1.1)

[0177] Figure 9 This is a block diagram of the headlight 200A according to Embodiment 1.1. The headlight 200A includes a variable light source 210, a power supply circuit 220A, and a control unit 260.

[0178] The power supply circuit 220A includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power control circuit 225A. The power control circuit 225A includes a feedback circuit 226A, a converter controller 228, and a voltage setting circuit 230.

[0179] The converter controller 228 can use a commercially available DC / DC converter control IC (Integrated Circuit). The converter controller 228 is fed by the feedback voltage V from the input feedback pin FB. FB Approximately the internally generated reference voltage V REF In a manner that generates a pulse signal with at least one of pulse width or frequency and duty cycle adjusted, the DC / DC converter 224 is subjected to feedback control based on the pulse signal.

[0180] In the voltage setting circuit 230, data S4 generated by the array-type light-emitting device 212 is input. Based on the received data S4, the voltage setting circuit 230 generates a correction voltage V. CMP The feedback circuit 226A operates based on the output voltage V of the DC / DC converter 224. OUT The corresponding controlled object voltage V CNT and correction voltage V CMP Generate feedback voltage V FB This is supplied to the feedback pin FB of the converter controller 228. The feedback voltage V... FB It is based on the voltage V of the controlled object. CNT and correction voltage V CMP The signals that change for each are represented by equation (1).

[0181] V FB =K1・V CNT +K2・V CMP …(1)

[0182] K1 is a constant greater than 0, and K2 is a non-zero constant. Here, we assume K2 < 0. This feedback signal V is then used by the converter controller 228. FB Approaching the target value V REF The DC / DC converter 224 is controlled in this manner.

[0183] Under a stable system state

[0184] K1・V CNT +K2・V CMP =V REF

[0185] Therefore, under steady-state conditions, the controlled object voltage V... CNT Stabilize at the target value V CNT（REF） .

[0186] V CNT（REF） = (V REF -K2・V CMP ) / K1…(2)

[0187] In this embodiment 1.1, the controlled object voltage VCNT The voltage V at the power supply terminal VDD of the array-type light-emitting device 212 is... DD .

[0188] The detection terminal SNS of the power supply circuit 220A is connected to the power terminal VDD of the array-type light-emitting device 212 via a detection line (magnetic line) LSNS, which is independent of the power cable 204 (power line LVDD). The input impedance of the feedback circuit 226A is sufficiently high, so no current flows in the detection line LSNS. Therefore, the detection voltage V... SNS The voltage V of the power supply terminal VDD of the array-type light-emitting device 212 DD Equal. The detection voltage V generated at the detection terminal SNS is equal. SNS Voltage V, the object of control CNT In the input feedback circuit 226A, therefore, the power supply voltage V... DD Target value V DD（REF） It is expressed as equation (3).

[0189] V DD（REF） = (V REF -K2・V CMP ) / K1…(3)

[0190] That is, by changing the correction voltage V according to data S4 CMP This allows the power supply voltage V to be changed. DD Target value V DD（REF） .

[0191] The above describes the structure of the 200A headlight. Next, its operation will be explained. Figure 10 yes Figure 9 The waveform diagram of the operation of the headlight 200A. This operation corresponds to the control example 1 above.

[0192] Under steady-state conditions, the correction voltage V CMP The value is a stable value (0V in this example). At time t1, the switching from light distribution pattern PTN1 to PTN2 is indicated. At the preceding time t0, the voltage setting circuit 230 increases the correction voltage V. CMP As a result, the target value V, expressed in equation (3), can be obtained. DD（REF） The voltage is shifted to the higher potential side. Subsequently, the voltage setting circuit 230 sets the correction voltage V... CMP Returns a stable value.

[0193] At time t2, the current I... OUT This reduces changes in the light distribution pattern. In this case, the voltage setting circuit 230 will correct the voltage V. CMP It is sufficient to maintain a stable value.

[0194] The above describes the operation of headlight 200A. Based on headlight 200A, the correction voltage V is changed according to data S4. CMP This allows for dynamic control of the voltage V at the power supply terminal VDD of the array-type light-emitting device 212. DD Target value V DD（REF） .

[0195] Next, an example of the structure of the voltage setting circuit 230 and the feedback circuit 226A will be described.

[0196] Figure 11 This is a circuit diagram showing an example of the structure of feedback circuit 226A. Feedback circuit 226A is a subtraction circuit with an amplifier, including resistors R31 to R34 and amplifier OA3. The input-output characteristics of feedback circuit 226A are expressed by equation (5).

[0197] V FB =(R31+R32) / R31×{R34 / (R33+R34)×V CNT -R32 / (R31+R32)×V CMP …(5)

[0198] Comparing equations (1) and (5), we obtain

[0199] K1=(R31+R32) / R31×R34 / (R33+R34)

[0200] K2=-(R31+R32) / R31×R32 / (R31+R32).

[0201] Furthermore, the feedback circuit 226A can be constructed using an adder circuit employing an amplifier. In this case, K1 > 0, K2 > 0. When the correction voltage V CMP When it is positive, it can be based on the correction voltage V CMP To make the voltage V of the controlled object CNT The target value is shifted to the lower potential side.

[0202] Figure 12 This is a circuit diagram showing an example of the structure of the voltage setting circuit 230. The voltage setting circuit 230 includes a microcontroller 240, a D / A converter 234, and a buffer 236. The microcontroller 240 sets the voltage setting circuit according to the positive voltage V of the light-emitting element 213. F The relevant data S4 generates the specified correction voltage V. CMP The numerical setting value D CMP By using the microcontroller 240, it is possible to correct the voltage V. CMP Implement software control.

[0203] D / A converter 234 converts the set value D generated by microcontroller 240 into an A / D converter. CMPConverted to analog correction voltage V CMP Correction voltage V CMP The output impedance of the D / A converter 234 is supplied to the feedback circuit 226A via buffer 236. Furthermore, if the output impedance of the D / A converter 234 is sufficiently low, the buffer 236 can be omitted. Additionally, when using a microcontroller 240 integrated with the D / A converter, the D / A converter 234 resides within the microcontroller 240.

[0204] (Example 1.2)

[0205] Figure 13 This is a block diagram of the headlight 200B according to Embodiment 1.2. The structure of the headlight 200B will be described focusing on its differences from that of Embodiment 1.1. The headlight 200B includes a variable light source 210, a power supply circuit 220B, and a control unit 260. In Embodiment 1.2, the structure of the power supply circuit 220B differs from that of the power supply circuit 220A in Embodiment 1.1.

[0206] The power supply circuit 220B includes an output terminal OUT, a DC / DC converter 224, and a power control circuit 225B. The power control circuit 225B includes a feedback circuit 226B, a converter controller 228, and a voltage setting circuit 230.

[0207] In Example 1.2, the output voltage V of the DC / DC converter 224 OUT For the control object voltage V CNT The output voltage V generated at the output terminal OUT. OUT Voltage V, the object of control CNT The input is fed into the feedback circuit 226B. Therefore, the output voltage V... OUT Target value V OUT（REF） It is represented by equation (6). Similarly, the feedback circuit 226B can also be a subtraction circuit, just like the feedback circuit 226A in embodiment 1.1.

[0208] V OUT（REF） = (V REF -K2・V CMP ) / K1…(6)

[0209] Next, the operation of the headlight 200B will be explained. In Example 1.2, any of the control methods described in Control Examples 2 to 4 above can be used.

[0210] Figure 14 This is the operating waveform diagram of the headlight 200B using Control Example 2. During periods T1 to T3, the light distribution patterns PTN1 to PTN3 are set, and the output current I... OUT Take I OUT1 I OUT2 I OUT3 The way it changes.

[0211] In each light distribution pattern PTN1 to PTN3, the correction voltage V CMP With output current I OUT Essentially proportional. According to this control, by adjusting the output current I... OUT Change the target value V OUT（REF） The power supply voltage V can be DD Keep it constant.

[0212] Figure 15 This is the waveform diagram of the operation of the headlight 200B using control example 4. Correction voltage V CMP Including output current I OUT The components that are substantially proportional, and the components that arise during a certain period before and after the change in the light distribution pattern (marked with shading). The former corresponds to... Figure 14 The correction voltage V shown CMP .

[0213] According to Control Example 4, when a change in the light distribution pattern occurs as the current increases, the output voltage V can be temporarily increased. OUT Target value V OUT（REF） .

[0214] The above describes the operation of headlight 200B. Based on headlight 200B, the calibration voltage V can be used... CMP Set the output voltage V of the DC / DC converter 224. OUT The target value.

[0215] (Example 1.3)

[0216] Figure 16 This is a block diagram of the headlight 200C according to Embodiment 1.3. The structure of the headlight 200C will be described focusing on the differences from Embodiment 1.2.

[0217] The headlight 200C includes a variable light source 210, a power supply circuit 220C, and a control unit 260. In Embodiment 1.3, the structure of the power supply circuit 220C differs from that of the power supply circuit 220B in Embodiment 1.2.

[0218] The structure of power supply circuit 220C is described below. Power supply circuit 220C includes output terminal OUT, detection terminal SNS, DC / DC converter 224, and power control circuit 225C.

[0219] The power control circuit 225C includes a feedback circuit 226C, a converter controller 228, and a voltage setting circuit 230.

[0220] In the feedback circuit 226C, the voltage V, which is the controlled object, is... CNT Input and output voltage VOUT Furthermore, the power supply voltage V is input to the feedback circuit 226C via the detection line LSNS. DD Furthermore, the correction voltage V generated by the input voltage setting circuit 230 is fed into the feedback circuit 226C. CMP .

[0221] The voltage setting circuit 230 generates the correction voltage V CMP The stable value is taken under stable conditions. When a change in the light distribution pattern occurs accompanied by an increase in current, the voltage setting circuit 230 increases the correction voltage V. CMP .

[0222] Feedback circuit 226C is based on three voltages V OUT V SNS V CMP Generate feedback voltage V FB Feedback circuit 226C is based on V OUT and V SNS The differential voltage drop V at the LVDD power line is detected. DROP =V OUT -V SNS .

[0223] The feedback voltage V generated by the feedback circuit 226C FB It is represented by equation (8).

[0224] V FB =K1・V OUT +K2・V CMP +K3・V DROP …(8)

[0225] The above describes the structure of the headlight 200C. In this headlight 200C, the controlled voltage is the output voltage V. OUT Target value V OUT（REF） It is represented by equation (9).

[0226] V OUT（REF） = (V REF -K2・V CMP -K3·V DROP ) / K1…(9)

[0227] If we set K2 < 0, K3 < 0...

[0228] V OUT（REF） = (V REF +|K2|・V CMP +|K3|·V DROP ) / K1…(9') 。 When |K3|=K1 holds true,

[0229] V OUT（REF） = (VREF +|K2|・V CMP ) / K1+V DROP …(9'')

[0230] According to Example 1.3, the actual measured voltage drop V can be used as a basis for calculation. DROP This makes the output voltage V OUT Target value V OUT（REF） The most appropriate approach can reduce power consumption. Furthermore, by correcting the voltage V... CMP This can restore the voltage drop caused by the response delay. Furthermore, by appropriately determining the gain K3, the voltage drop across the ground wire LGND can also be corrected.

[0231] Figure 17 This is a functional block diagram of the feedback circuit 226C. The feedback circuit 226C can also include three subtraction circuits SUB1 to SUB3. Subtraction circuit SUB1 draws voltage from the output voltage V. OUT Subtract the detection voltage V SNS Calculate the voltage drop V DROP The subtraction circuit SUB2 draws voltage from the output voltage V. OUT Subtract voltage drop V DROP The subtraction circuit SUB3 receives the output voltage V from the subtraction circuit SUB2. OUT -V DROP Subtract the correction voltage V CMP The order of subtraction can be changed.

[0232] (Example 1.4)

[0233] Figure 18 This is a circuit diagram of the headlight 200D according to Embodiment 1.4. The headlight 200D includes a variable light source 210, a power supply circuit 220D, and a control unit 260.

[0234] The structure of power supply circuit 220D is described. Power supply circuit 220D includes output terminal OUT, detection terminal SNS, DC / DC converter 224, and power control circuit 225D.

[0235] The power control circuit 225D includes a feedback circuit 226D, a converter controller 228D, and a voltage setting circuit 230D. In this embodiment, the converter controller 228D has a reference voltage setting pin REF, which can set the voltage according to the reference signal S input to the reference voltage setting pin REF. REF Set the reference voltage V REF The converter controller 228D can convert the reference signal S... REF As a digital signal receiver, it generates a reference voltage V through an internal voltage source. REF Alternatively, the converter controller 228D can receive an analog reference signal S.REF It is directly used as the internal reference voltage V. REF The converter controller 228D uses the voltage V of the feedback pin FB. FB Approaching the reference signal S REF The reference voltage V REF The DC / DC converter 224 is controlled by feedback in this manner.

[0236] The voltage setting circuit 230D generates a reference signal S based on data S4. REF The reference voltage setting pin REF is supplied to the converter controller 228D. When the reference signal S... REF In the case of analog voltage, the voltage setting circuit 230D can be used with... Figure 12 Similarly, the correction voltage V is constructed. CMP Replace with reference signal S REF That's it. Reference signal S REF When the signal is digital, the voltage setting circuit 230D can be controlled solely by... Figure 12 The microcontroller 240 is configured to set the value D. CMP Replace with reference signal S REF That's all.

[0237] Feedback circuit 226D generates and controls the object voltage V CNT The corresponding feedback voltage V FB The feedback pin FB is supplied to the converter controller 228D.

[0238] Similar to Example 1.2, the controlled object voltage V CNT It can also be the output voltage V OUT In this case, the feedback voltage V FB It is represented by equation (10).

[0239] V FB =K1・V OUT …(10)

[0240] Similar to Example 1.1, the power supply circuit 220D and the variable light source 210D are connected via the detection line LSNS to transmit the detection voltage V. SNS (=V) DD Voltage V, as the controlled object CNT The feedback voltage V in this case FB It is represented by equation (11).

[0241] V FB =K1・V SNS =K1・V DD …(11)

[0242] Similar to Example 1.3, the output voltage V can be...OUT Voltage V, the object of control CNT The voltage drop V in the LVDD power line will be corrected. DROP The voltage after that is used as the feedback voltage V FB The feedback voltage V in this case FB It is represented by equation (12).

[0243] V FB =K1・V OUT +K3・V DROP …(12)

[0244] As illustrated in Example 1.3, the voltage drop V DROP The power supply circuit 220D and the variable light source 210D can be connected using the detection line LSNS, and V can be calculated. OUT and V SNS It is obtained by the difference.

[0245] According to Example 1.4, the same effect as in Examples 1.1 to 1.3 was obtained.

[0246] Next, variations related to Implementation Method 1 will be described.

[0247] (Variation 1.1)

[0248] Figure 19 This is a diagram showing the headlight 200 of Modification 1.1. In the preceding description, the variable light source 210 includes one array-type light-emitting device 212, but the variable light source 210 may also include multiple array-type light-emitting devices 212. In this case, the power supply circuit 220 can be modularized (referred to as power supply unit 222), and multiple power supply units 222 can be provided corresponding to the multiple array-type light-emitting devices 212. The output terminal of each power supply unit 222 is connected to the power supply terminal of the corresponding array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, as needed, a detection line LSNS can be provided for each pair of power supply units 222 and array-type light-emitting devices 212. In this modification, the microcontroller 240 is common to multiple power supply units.

[0249] In this variation 1.1, the variable light source 210 is configured as multiple array-type light-emitting devices 212, each with its own independent power supply terminal. Furthermore, a power supply unit 222 is provided for each array-type light-emitting device 212, and the array-type light-emitting device 212 and the power supply unit are connected one-to-one via power cables. This allows the current flowing in the variable light source 210 to be distributed across multiple DC / DC converters in the system, reducing the impact of voltage drop in each DC / DC converter and improving load responsiveness. In addition, the options for the components, power cables, and connectors of the DC / DC converters increase, enhancing design freedom.

[0250] (Variation 1.2)

[0251] Figure 20 This diagram shows the headlight 200 of Modified Example 1.2. The array-type light-emitting device 212 may consist of multiple internal light-emitting pixels divided into multiple segments SEG1 to SEGn, with multiple power supply terminals VDD corresponding to each segment SEG1 to SEGn. In the power supply circuit 220, multiple power supply units 222 are provided corresponding to the multiple power supply terminals VDD. The output terminal OUT of each power supply unit 222 is connected to the corresponding power supply terminal VDD of the array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, a detection line LSNS may be provided for each power supply unit 222 as needed.

[0252] In this variation 1.2, the current flowing in the variable light source 210 is distributed among multiple DC / DC converters in the system, achieving the same effect as in variation 1.1.

[0253] (Variation 1.3)

[0254] The power supply unit 222 can be constructed using a phase-shift converter. By employing a phase-shift converter, the output voltage V can be reduced compared to a single-phase converter. OUTi Or output current I OUTi This reduces ripple and improves efficiency. Furthermore, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I of the power supply unit 222... OUTi The brightness varies rapidly depending on the illumination rate of multiple pixel circuits, but by employing a phase-shift converter, the responsiveness to load variations can be improved.

[0255] (Variation 1.4)

[0256] This describes the case where the power supply circuit 220 or the control unit 260 is built into the headlight 200, but one or both of them can also be located on the outside of the headlight body 200. Since the variable light source 210 is a heat-generating element, it is advantageous from a thermal design point of view to have the control unit 260 located away from the variable light source 210 within the vehicle interior to avoid heat.

[0257] (Variation 1.5)

[0258] The power control circuit 225 can receive information related to the light distribution pattern directly from the host controller 104 without going through the control unit 260.

[0259] (Variation 1.6)

[0260] The power control circuit 225 can disregard the on / off ground of multiple pixel circuits (PIX) and operate based on the positive voltage V of all pixels. F1 ~V Fn The maximum value determines the target value. The power control circuit 225 can be used in multiple pixel circuits (PIX) to determine the target value based on the positive voltage V of the actually lit pixel. F The maximum value determines the target value.

[0261] (Variation 1.7)

[0262] Array-type light-emitting devices allow for the pre-determining of the forward voltage V of multiple internal light-emitting elements. F The maximum value is V F（MAX） It is stored in internal non-volatile memory. Positive voltage V F（MAX） It could be the maximum value across all pixels and all temperature ranges. Alternatively, it could store the positive voltage V for each temperature range. F（MAX） Send data containing the maximum value corresponding to the current temperature.

[0263] (Implementation Method 2)

[0264] Figure 21 This is a block diagram of the lighting system 100 according to Embodiment 2. The lighting system 100 is an ADB lighting system, including a battery 102, a host controller 104, and a headlight 200.

[0265] The host controller 104 generates a beam distribution command for the headlight 200. The beam distribution command may include a lighting command and additional information. The lighting command may include a signal indicating whether the high beam or low beam is on or off. Based on the lighting command, the basic beam distribution that the headlight 200 should form is determined. Furthermore, the additional information may include data related to the area where high beams should not be emitted (the shaded area), vehicle speed, steering angle, etc. Based on the additional information, the basic beam distribution is corrected, and the final beam distribution is determined. The host controller 104 may be configured as a vehicle-side ECU (Electronic Control Unit) or as an ECU built into the lamp-side of the headlight 200.

[0266] The headlight 200 is an ADB lamp that includes a variable light source 210, a power supply circuit 220, a connection unit 202, and a control unit 260.

[0267] The variable light source 210 includes multiple pixels arranged in an array, each of which can be individually controlled to be turned on or off. In the headlight 200, the on / off state of multiple pixels is controlled in a manner that achieves the desired light distribution.

[0268] More specifically, the variable light source 210 includes an array-type light-emitting device 212. The array-type light-emitting device 212 has n pixel circuits PIX1 to PIXn and a power supply terminal VDD connected to the multiple pixel circuits PIX1 to PIXn.

[0269] The pixel circuit PIXj (1≦j≦n) includes a light-emitting element 213_j and a current source 214_j connected in series between the power supply terminal VDD and the ground terminal (grounding wire) GND. The multiple light-emitting elements 213_1 to 213_n are semiconductor light-emitting elements such as LEDs, LDs (semiconductor lasers), and organic EL elements, and are arranged in an array (matrix) in space.

[0270] Multiple current sources 214_1 to 214_n can be controlled to turn on and off independently. When the j-th current source 214_j is turned on, the corresponding light-emitting element 213_j emits light, and its pixel circuit PIXj is in the lit state.

[0271] The interface circuit 216 controls the current sources 214_1 to 214_n to turn on and off according to the control signal S2 from the control unit 260. The interface circuit 216 is connected to the control unit 260 via a high-speed serial interface and receives the control signal S2 indicating the on and off status of all pixels.

[0272] Power supply circuit 220 supplies power to the variable light source 210. Power supply circuit 220 includes a constant voltage output converter that supplies a stabilized power supply voltage V to the power supply terminal VDD of the array-type light-emitting device 212. DD Power supply voltage V DD According to V F +V SAT Yes, typically around 4-5V. F V is the forward voltage of the light-emitting element 213. SAT This is the minimum operating voltage for current source 214. Therefore, power supply circuit 220 can be supplied with a battery voltage of approximately 12V (or 24V). BAT It consists of a buck converter.

[0273] The control unit 260 receives a light distribution command S1 from the host controller 104, generates a control signal S2 corresponding to the light distribution command S1, and sends it to the variable light distribution light source 210. The control unit 260 is also called a drawing ECU. For example, the control unit 260 performs PWM control on multiple pixel circuits PIX1 to PIXn of the array-type light-emitting device 212 to control the light distribution. The PWM frequency is several hundred Hz (e.g., 100 to 400 Hz), so the PWM period is several milliseconds to tens of milliseconds (ms).

[0274] The power supply circuit 220 and the array-type light-emitting device 212 are connected via a connection unit 202 that includes a power cable 204. In addition to the power cable 204, the connection unit 202 may also include connectors (couplers) 206A, 206B, etc.

[0275] Next, the configuration of the power supply circuit 220 will be described. The power supply circuit 220 includes a DC / DC converter 224 and a power control circuit 225.

[0276] The power cable 204 includes a power line LVDD and a ground line LGND. The positive output terminal OUTP of the DC / DC converter 224 is connected to the power terminal VDD of the array-type light-emitting device 212 via the power line LVDD. In addition, the negative output terminal OUTN of the DC / DC converter 224 is connected to the ground terminal GND of the array-type light-emitting device 212 via the ground line LGND.

[0277] Set the impedance of the power line LVDD and the ground line LGND to R. VDD R GND .

[0278] The voltage V from the battery is supplied to the input of the DC / DC converter 224. BAT Its output is connected to the array-type light-emitting device 212 via the connection unit 202. The power control circuit 225 obtains the voltage drop V of the connection unit 202. DROP .

[0279] Voltage drop V of connection unit 202 DROP This may include the voltage drop in the power cable 204 and the voltage drop in the connector 206. More specifically, the voltage drop V in the connection unit 202... DROP This may include the voltage drop V1 of the power line LVDD, the voltage drop V2 of the ground line LGND, the voltage drop V3 of connector 206A, and the voltage drop V4 of connector 206B. The power control circuit 225 can use the sum of these voltage drops V1 to V4 as the voltage drop V of the connection unit 202. DROP Obtain.

[0280] V DROP =V1 + V2 + V3 + V4

[0281] Alternatively, if the voltage drop in connector 206 is relatively small compared to the voltage drop in power cable 204, the voltage drops V1 and V2 in power cable 204 can be used as the voltage drop V. DROP Obtain.

[0282] V DROP =V1 + V2

[0283] Alternatively, when the vehicle body is used as the grounding wire LGND, its impedance is very low. In this case, only the voltage drop V1 of the power line LVDD of the power cable 204 can be taken as the voltage drop V. DROP .

[0284] The power control circuit 225 determines the voltage drop V based on the obtained voltage drop. DROP Set the target value V OUT（REF） .

[0285] V OUT（REF） =V DD（MIN） +V DROP

[0286] Furthermore, the power control circuit 225 uses the output voltage V of the DC / DC converter 224. OUT Approaching the target value V OUT（REF） In this way, the DC / DC converter 224 is controlled.

[0287] The above describes the structure of the lighting system 100. Next, the operation of the lighting system 100 will be explained.

[0288] Figure 22 This is an explanation Figure 21 A diagram illustrating the operation of the lighting system 100. Output current I. OUT It changes constantly. In connection unit 202, the output current I is generated. OUT proportional voltage drop V DROP .

[0289] V DROP =R×I OUT

[0290] R is the impedance of connection unit 202.

[0291] The power control circuit 225 obtains the voltage drop V. DROP The voltage drop V is set and obtained. DROP The corresponding target value V OUT（REF） Furthermore, the power control circuit 225 controls the output voltage V of the DC / DC converter 224. OUT Stabilizes at the target value V expressed by the above formula OUT（REF） .

[0292] The input voltage VB applied between the power supply terminal VDD and the ground terminal GND of the array-type light-emitting device 212 is compared to the voltage V between the positive and negative outputs OUTP and OUTN of the DC / DC converter 224. A That is, the output voltage V of the DC / DC converter 224 OUT The voltage drop V in the low connection unit 202 DROPThe amount. In this embodiment, the power supply circuit 220 generates a voltage drop V of the connection unit 202. DROP Partial, additional output voltage V OUT Thus, the input voltage V of the array-type light-emitting device 212 B Regardless of voltage drop V DROP The magnitude of the voltage remains constant. Therefore, the power supply voltage V DD Regardless of the output current I OUT The ground voltage can be maintained at the minimum operating voltage V. DD（MIN） Nearby, unnecessary power consumption can be reduced.

[0293] This invention can be used as Figure 21 The invention is not limited to any particular configuration, but rather is understood through block diagrams or circuit diagrams, or by various devices and methods derived from the above description. The following description is not intended to limit the scope of the invention, but rather to aid in understanding the nature or operation of the invention, or to clarify it, by providing more specific structural examples or embodiments.

[0294] (Example 2.1)

[0295] Figure 23 This is a block diagram of the headlight 200A according to Embodiment 2.1. The headlight 200A includes a variable light source 210, a power supply circuit 220A, and a control unit 260.

[0296] The power supply circuit 220A includes a DC / DC converter 224, a current sensor 223, and a power control circuit 225A.

[0297] The current sensor 223 generates the output current I of the DC / DC converter 224. OUT The corresponding current detection signal VCS. For example, current sensor 223 includes a sensing resistor Rs and an amplifier AMP1. The sensing resistor Rs is set at the output current I. OUT On the path. Furthermore, the sensing resistor Rs is in Figure 23 The current sensor is positioned on the positive output terminal OUTP side, but it can also be positioned on the negative output terminal OUTN side. Amplifier AMP1 amplifies the voltage drop generated by the sensing resistor Rs and outputs the current detection signal V. CS The current detection signal V CS With output current I OUT Proportional, therefore, is related to the voltage drop V of the connection unit 202. DROP The corresponding signal. When the detection gain of the current sensor 223 is set to A, the following formula holds true.

[0298] V CS =A×I OUT

[0299] The power control circuit 225A is based on the voltage drop V DROP Correlated current detection signal V CS Set the target value V OUT（REF） Controls the DC / DC converter 224.

[0300] In embodiment 2.1, the power control circuit 225A includes a feedback circuit 226A and a converter controller 228. The converter controller 228 can use a commercially available DC / DC converter control IC (Integrated Circuit). The converter controller 228 is connected to the feedback voltage V input at the feedback pin FB. FB Approximately the internally generated reference voltage V REF In this manner, a pulse signal is generated that adjusts at least one of the pulse width or frequency and duty cycle, and feedback control is performed on the DC / DC converter 224 based on the pulse signal.

[0301] Feedback circuit 226A receives the output voltage V from DC / DC converter 224. OUT Subtract the current detection signal V CS Correction voltage V CMP Generate feedback voltage V FB Furthermore, the feedback voltage V FB Feedback pin FB is supplied to converter controller 228.

[0302] Feedback voltage V FB It corresponds to the output voltage V OUT and correction voltage V CMP The signals that change for each are represented by equation (1).

[0303] V FB =K1・V OUT -K2・V CMP …(1)

[0304] K1, K2 > 0

[0305] Through the converter controller 228, with the feedback signal V FB Approaching the target value V REF The DC / DC converter 224 is controlled in this manner.

[0306] Under a stable system state

[0307] K1・V OUT -K2・V CMP =V REF

[0308] This is true. Therefore, under steady-state conditions, the output voltage V... OUT Stabilizes at the target value V expressed by equation (2)OUT（REF） .

[0309] V OUT（REF） = (V REF +K2・V CMP ) / K1…(2)

[0310] Therefore, when V CMP =V CS =A×I OUT At that time,

[0311] V OUT（REF） = (V REF +K2・A×I OUT ) / K1…(2') .

[0312] K2 / K1・A is the impedance R of the connection unit 202, expressed as V. REF / K1 is V DD（MIN） By determining the circuit constants in this way, they can be set as follows:

[0313] V OUT（REF） =V DD（MIN） +I OUT ×R=V DD（MIN） +V DROP .

[0314] Figure 24 This is a circuit diagram showing an example of the structure of feedback circuit 226A. Feedback circuit 226A includes a subtraction circuit 227 with an amplifier. Subtraction circuit 227 includes resistors R31 to R34 and an amplifier OA3. The input-output characteristics of subtraction circuit 227 are expressed by equation (3).

[0315] Vx=(R31+R32) / R31×{R34 / (R33+R34)×V CNT -R32 / (R31+R32)×V CMP …(3)

[0316] The output voltage Vx of the subtraction circuit 227 can be set as the feedback voltage V. FB Alternatively, the voltage Vx can be divided using resistors R35 and R36, resulting in a voltage Vx. FB 'As feedback voltage output'.

[0317] In Vx=V FB In the case of comparing equation (1) and equation (3), we obtain

[0318] K1=(R31+R32) / R31×R34 / (R33+R34)

[0319] K2=(R31+R32) / R31×R32 / (R31+R32).

[0320] (Example 2.2)

[0321] Figure 25 This is a block diagram illustrating the headlight 200B of Embodiment 2.2. The headlight 200B includes a variable light source 210, a power supply circuit 220B, and a control unit 260.

[0322] The power supply circuit 220B includes a DC / DC converter 224, a power control circuit 225B, and a detection terminal SNS.

[0323] The detection terminal SNS is connected to the power supply terminal VDD of the array-type light-emitting device 212 via a detection line (magnetic line) LSNS, which is independent of the connection unit 202. The input impedance of the power control circuit 225B is sufficiently high, so no current flows in the detection line LSNS. Therefore, the detection voltage V generated by the detection terminal SNS... SNS The voltage V of the power supply terminal VDD of the array-type light-emitting device 212 DD equal.

[0324] The power control circuit 225B controls the output voltage V of the DC / DC converter 224. OUT and the detection voltage V of the detection terminal SNS SNS The difference ΔV = V OUT -V SNS Obtain the voltage drop V of the connection unit 202. DROP The differential ΔV represents the voltage drop across the power supply line LVDD and the connector on the positive side of the connection unit 202.

[0325] For example, when the impedance on the positive side of connection unit 202 is equal to the impedance on the negative side, ΔV×2 represents the voltage drop V of connection unit 202. DROP The power control circuit 225B includes amplifier AMP2, feedback circuit 226B, and converter controller 228. Amplifier AMP2 amplifies the output voltage V. OUT With the detection voltage V SNS The difference generates a correction voltage V. CMP The correction voltage V CMP With output current I OUT Proportional.

[0326] V CMP =B×(V) OUT -V SNS ) = A × I OUT

[0327] Feedback circuit 226B obtains the output voltage V from DC / DC converter 224. OUT Subtract the correction voltage V CMPGenerate feedback voltage V FB Furthermore, the feedback voltage V FB Feedback pin FB is supplied to converter controller 228.

[0328] Feedback voltage V FB It is based on the output voltage V OUT and correction voltage V CMP The signals that change for each are represented by equation (1).

[0329] V FB =K1・V OUT -K2・V CMP …(1 more)

[0330] Through the converter controller 228, with the feedback signal V FB Approaching the target value V REF The DC / DC converter 224 is controlled in a manner that allows it to operate at a steady state. The output voltage V... OUT Stabilizes at the target value V expressed by equation (2) OUT（REF） .

[0331] V OUT（REF） = (V REF +K2・V CMP ) / K1…(again 2)

[0332] Therefore, when V CMP =A×I OUT At that time,

[0333] V OUT（REF） = (V REF +K2・A×I OUT ) / K1…(2') .

[0334] K2 / K1・A is the impedance R of the connection unit 202, expressed as V. REF / K1 becomes V DD（MIN） By determining the circuit constants in this way, they can be set as follows:

[0335] V OUT（REF） =V DD（MIN） +I OUT ×R=V DD（MIN） +V DROP .

[0336] (Example 2.3)

[0337] Figure 26 This is a block diagram of the headlight 200C according to Embodiment 2.3. The headlight 200C includes a variable light source 210, a power supply circuit 220C, and a control unit 260.

[0338] The power supply circuit 220C includes a DC / DC converter 224, a current sensor 223, and a power control circuit 225C.

[0339] The current sensor 223 generates the output current I of the DC / DC converter 224. OUT The corresponding current detection signal V CS .

[0340] V CS =A×I OUT

[0341] The power control circuit 225C includes a voltage setting circuit 230C and a converter controller 228C. In addition to the feedback pin FB, the converter controller 228C has a reference voltage setting pin REF, which is based on a reference signal S input to the reference voltage setting pin REF. REF It can set the reference voltage V REF The converter controller 228C receives the analog reference signal S. REF It is directly used as the internal reference voltage V. REF The converter controller 228C uses the voltage V of the feedback pin FB. FB Approaching the reference signal S REF The reference voltage V REF The DC / DC converter 224 is controlled by feedback in this manner.

[0342] The input and output voltage V is fed to the feedback pin FB of the converter controller 228C. OUT The corresponding feedback voltage V FB In this example, the feedback voltage V FB It is the output voltage V OUT The voltage of the voltage divider is expressed by the following formula (4).

[0343] V FB =K1×V OUT …(4)

[0344] The voltage setting circuit 230C generates and connects the voltage drop V of the unit 202. DROP The corresponding reference signal S REF The voltage is supplied to the reference voltage setting pin REF of the converter controller 228C. In this embodiment, the voltage setting circuit 230C sets the specified voltage V... REG and based on current detection signal V CS Correction voltage V CMP The two voltages are added together to generate a simulated reference voltage V. REF .

[0345] V REF =K2・V REG +K3・VCMP …(5)

[0346] In a steady state, V REF =V FB This is true, thus yielding equation (6).

[0347] K2・V REG +K3・V CMP =K1×V OUT …(6)

[0348] Therefore, the output voltage V OUT Target value V OUT（REF） It is represented by equation (7).

[0349] V OUT（REF） = (K2・V) REG +K3・V CMP ) / K1…(7)

[0350] In equation (7), substituting V CMP =V CS =A×I OUT Then, we get equation (8).

[0351] V OUT（REF） = (K2・V) REG +K3・A×I OUT ) / K1…(8)

[0352] Therefore, K2 / K1×V REG =V DD（MIN） By using the method K3・A / K1=R, the circuit constants can be determined, thereby allowing the setting of...

[0353] V OUT（REF） =V DD（MIN） +R×I OUT .

[0354] (Example 2.4)

[0355] Figure 27 This is a block diagram of the headlight 200D according to Embodiment 2.4. The headlight 200D includes a variable light source 210, a power supply circuit 220D, and a control unit 260.

[0356] The power supply circuit 220D includes a DC / DC converter 224, a power control circuit 225D, and a detection terminal SNS. The detection terminal SNS is connected to the power supply terminal VDD of the array-type light-emitting device 212 via a detection line (magnetic line) LSNS, which is independent of the connection unit 202.

[0357] The power control circuit 225D includes an amplifier AMP3, a voltage setting circuit 230D, and a converter controller 228D. The converter controller 228D replaces the feedback pin FB and has a reference voltage setting pin REF, which can adjust the voltage based on the reference signal S input to the reference voltage setting pin REF. REF Set the reference voltage V REF Input V to the feedback pin of converter controller 228D. FB =K1×V OUT .

[0358] Amplifier AMP3 amplifies the output voltage V OUT and detection voltage V SNS The difference generates a correction voltage V. CMP The correction voltage V CMP With output current I OUT Proportional.

[0359] V CMP =B×(V) OUT -V SNS ) = A × I OUT

[0360] The voltage setting circuit 230D generates and connects the voltage drop V of the unit 202. DROP The corresponding reference signal S REF The voltage is supplied to the reference voltage setting pin REF of the converter controller 228D. In this embodiment, the voltage setting circuit 230D sets the specified voltage V... REG With correction voltage V CMP The two voltages are added together to generate a simulated reference voltage V. REF .

[0361] V REF =K2・V REG +K3・V CMP …(9)

[0362] In this power supply circuit 220D, the output voltage V OUT Target value V OUT（REF） It is represented by equation (10).

[0363] V OUT（REF） = (K2・V) REG +K3・V CMP ) / K1…(10)

[0364] In equation (10), substituting V CMP =A×I OUT Then, we get equation (11).

[0365] V OUT（REF） = (K2・V) REG+K3・A×I OUT ) / K1…(11)

[0366] Therefore, to become K2 / K1×V REG =V DD（MIN） The circuit constants can be determined by using the method K3・A / K1=R, and can be set as follows:

[0367] V OUT（REF） =V DD（MIN） +R×I OUT .

[0368] Explain variations related to implementation method 2.

[0369] (Variation 2.1)

[0370] Figure 28 This diagram shows the headlight 200 of Modification 2.1. In the preceding description, the variable light source 210 has one array-type light-emitting device 212, but the variable light source 210 can have multiple array-type light-emitting devices 212. In this case, the power supply circuit 220 can be modularized (referred to as power supply unit 222), and multiple power supply units 222 can be provided corresponding to the multiple array-type light-emitting devices 212. The output terminal of each power supply unit 222 is connected to the power supply terminal of the corresponding array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, as needed, detection lines LSNS can be provided for each pair of power supply units 222 and array-type light-emitting devices 212. In this modification, the microcontroller 240 can be common to multiple power supply units.

[0371] In this variation 2.1, the variable light distribution light source 210 is configured as multiple array-type light-emitting devices 212, each with its own independent power supply terminal. Furthermore, a power supply unit 222 is provided for each array-type light-emitting device 212, and the array-type light-emitting device 212 and the power supply unit are connected one-to-one via power cables. This allows the current flowing in the variable light distribution light source 210 to be distributed across multiple DC / DC converters in the system, reducing the impact of voltage drop in each DC / DC converter and improving load responsiveness. In addition, the options for the components, power cables, and connectors of the DC / DC converters increase, enhancing design freedom.

[0372] (Variation 2.2)

[0373] Figure 29This diagram shows the headlight 200 of Modified Example 2.2. The array-type light-emitting device 212 may have multiple internal light-emitting pixels divided into multiple segments SEG1 to SEGn, with multiple power supply terminals VDD corresponding to each segment SEG1 to SEGn. In the power supply circuit 220, multiple power supply units 222 are provided corresponding to the multiple power supply terminals VDD. The output terminal OUT of each power supply unit 222 is connected to the corresponding power supply terminal VDD of the array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, a detection line LSNS can be set for each power supply unit 222 as needed.

[0374] In this variation 2.2, the current flowing in the variable light source 210 can be distributed among multiple DC / DC converters in the system, achieving the same effect as in variation 2.1.

[0375] (Variation 2.3)

[0376] The power supply unit 222 can also be constructed using a phase-shift converter. By employing a phase-shift converter, the output voltage V can be reduced compared to a single-phase converter. OUTi Or output current I OUTi This reduces ripple and improves efficiency. Furthermore, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I of the power supply unit 222... OUTi The brightness of multiple pixel circuits varies rapidly, but by using a phase-shift converter, the responsiveness to load changes can be improved.

[0377] (Variation 2.4)

[0378] This describes the case where the power supply circuit 220 or the control unit 260 is built into the headlight 200, but one or both of them can also be located on the outside of the headlight body 200. Since the variable light source 210 is a heat source, it is advantageous from a thermal design point of view to arrange the control unit 260 away from the variable light source 210 in the vehicle interior to avoid heat.

[0379] (Variation 2.5)

[0380] In embodiments 2.1 to 2.4, the power control circuit 225 is constructed using analog circuitry, but it can also be partially or entirely constructed using digital circuitry. For example, the power control circuit 225 may include a microcontroller. The microcontroller can process the current detection signal V. CS Alternatively, the output voltage of amplifier AMP3 can be converted into a digital value to obtain the voltage drop V of connection unit 202. DROP The output voltage V is set through digital signal processing. OUT Target value V OUT（REF） .

[0381] (Variation 2.6)

[0382] In Embodiment 2.2 or Embodiment 2.4, the detection terminal SNS can be connected to the ground terminal GND of the array-type light-emitting device 212 via the detection line LSNS. In this case, amplifier AMP2 or AMP3 amplifies the voltage V of the detection terminal SNS. SNS The voltage difference between the output voltage OUTN of the DC / DC converter 224 and the output voltage OUTN is sufficient.

[0383] (Implementation Method 3)

[0384] Figure 30 This is a block diagram of the lighting system 100 according to embodiment 3. The lighting system 100 is an ADB lighting system, including a battery 102, a host controller 104, and a headlight 200.

[0385] The host controller 104 generates beam distribution instructions for the headlight 200. The beam distribution instructions may include a lighting command and additional information. The lighting command may include a signal indicating whether the high beam or low beam is on or off. Based on the lighting command, the basic beam distribution that the headlight 200 should form is determined. Furthermore, the additional information may include data related to the area where high beams should not be emitted (the shaded area), vehicle speed, steering angle, etc. Based on the additional information, the basic beam distribution is corrected, and the final beam distribution is determined. The host controller 104 may be configured as a vehicle-side ECU or as an ECU built into the lamp-side of the headlight 200.

[0386] The headlight 200 is an ADB lamp equipped with a variable light source 210, a power supply circuit 220, and a control unit 260.

[0387] The variable light source 210 includes multiple pixels arranged in an array, and each pixel can be individually controlled to be turned on or off. In the headlight 200, the on / off state of multiple pixels is controlled in a manner that achieves the desired light distribution.

[0388] More specifically, the variable light source 210 includes an array-type light-emitting device 212. The array-type light-emitting device 212 has n pixel circuits PIX1 to PIXn and a power supply terminal VDD connected to the multiple pixel circuits PIX1 to PIXn.

[0389] The pixel circuit PIXj (1≦j≦n) includes a light-emitting element 213_j and a current source 214_j connected in series between the power supply terminal VDD and the ground terminal (grounding wire) GND. The multiple light-emitting elements 213_1 to 213_n are semiconductor light-emitting elements such as LEDs, LDs (semiconductor lasers), and organic EL elements, and are arranged in an array (matrix) in space.

[0390] Multiple current sources 214_1 to 214_n can be controlled to turn on and off independently. When the j-th current source 214_j is turned on, the corresponding light-emitting element 213_j emits light, and its pixel circuit PIXj is in the lit state.

[0391] The interface circuit 216 controls the current sources 214_1 to 214_n to turn on and off according to the control signal S2 from the control unit 260. The interface circuit 216 is connected to the control unit 260 via a high-speed serial interface and receives the control signal S2 indicating the on and off status of all pixels.

[0392] Furthermore, the interface circuit 216 is configured to monitor the voltage drop (i.e., forward voltage) V of the light-emitting elements 213 of each of the multiple pixel circuits PIX1 to PIXn. F1 ~V Fn It can generate a voltage including the positive voltage V. F1 ~V Fn The relevant information data S3A. In this embodiment, this data S3A is sent to the power supply circuit 220 as data S3B via the control unit 260.

[0393] Power supply circuit 220 supplies power to the variable light source 210. Power supply circuit 220 includes a constant voltage output converter that supplies a stabilized power supply voltage V to the power supply terminal VDD of the array-type light-emitting device 212. DD Power supply voltage V DD According to V F +V SAT The typical value is around 4-5V. F It is the forward voltage of the light-emitting element 213, V SAT This is the minimum operating voltage of the current source 214. Therefore, the power supply circuit 220 can be powered by a battery voltage of approximately 12V (or 24V). BAT It consists of a buck converter.

[0394] The control unit 260 receives a light distribution command S1 from the host controller 104, generates a control signal S2 corresponding to the light distribution command S1, and sends it to the variable light distribution light source 210. The control unit 260 is also called the drawing ECU. For example, the control unit 260 performs PWM control on multiple pixel circuits PIX1 to PIXn of the array-type light-emitting device 212 to control the light distribution. The PWM frequency is several hundred Hz (e.g., 100 to 400 Hz), so the PWM period is several milliseconds to tens of milliseconds (ms).

[0395] Next, the structure of the power supply circuit 220 will be described. The power supply circuit 220 includes an output terminal AP / AN, a ground terminal GND, a DC / DC converter 224, and a power control circuit 225.

[0396] The output terminals AP / AN are connected to the power supply terminal VDD and ground terminal GND of the array-type light-emitting device 212 via power cable 204. Power cable 204 includes a power line LVDD and a ground line LGND. The positive output OUTP of the DC / DC converter 224 is connected to the power supply terminal VDD of the array-type light-emitting device 212 via output terminal AP and power line LVDD. The negative output OUTN of the DC / DC converter 224 is connected to the ground terminal GND of the array-type light-emitting device 212 via output terminal AN and ground line LGND. A voltage V from the battery is supplied to the input of the DC / DC converter 224. BAT .

[0397] The power control circuit 225 receives data S3B from the control unit 260. Based on the received data S3B, the power control circuit 225 determines the controlled object voltage V. CNT Target value V CNT（REF） To control the voltage V of the object CNT Approaching the target value V CNT（REF） In this way, the DC / DC converter 224 is controlled.

[0398] As detailed below, the controlled object voltage V CNT It can be the power supply voltage V of the array-type light-emitting device 212 DD It can also be the output voltage V of the DC / DC converter 224. OUT .

[0399] Controlled object voltage V CNT Target value V CNT（REF） The forward voltage V of the light-emitting element 213 corresponding to all channels can be used. F1 ~V Fn The maximum value V F（MAX） For example, the data S3B received by the power control circuit 225 may include the positive voltage V of the light-emitting elements 213 of all channels. F1 ~V Fn At this time, the power control circuit 225 can obtain a positive voltage V. F1 ~V Fn The maximum value V F（MAX） According to the maximum value V F（MAX） Generate target value V CNT（REF） Alternatively, the control unit 260 can acquire a positive voltage V. F1 ~V Fn The maximum value V F（MAX） This will contain the maximum value V F（MAX） The data S3B is sent to the power control circuit 225.

[0400] The above describes the structure of the lighting system 100. Figure 31 Figures (a) and (b) illustrate the operation of the lighting system 100. Here, the controlled voltage V... CNT Let V be the power supply voltage of the array-type light-emitting device 212. DD .

[0401] Figure 31 (a) and (b) illustrate the operation of different components of the lighting system 100. Figure 31 In (a), the forward voltage V of the i-th pixel PIXi of the array-type light-emitting device 212 Fi The maximum value V F（MAX） Controlled object voltage V CNT That is, the power supply voltage V DD Target value V DD（REF） According to

[0402] V DD（REF） =V D +V Fi（MAX） +α

[0403] Confirmed. V D α is the voltage drop of current source 214, and α is the margin.

[0404] exist Figure 31 In (b), the positive voltage V of the j-th pixel PIXj of the array-type light-emitting device 212 is... Fj The maximum value V F（MAX） Controlled object voltage V CNT That is, the power supply voltage V DD Target value V DD（REF） according to

[0405] V DD（REF） =V D +V Fj +α

[0406] Sure.

[0407] like Figure 31 As shown in (a) and (b), the forward voltage V was measured for the actual product. F Determine the target value V DD（REF） This allows it to exceed the value V specified by the standard. DD（SPEC） Further reduce the power supply voltage V DD This reduces the power consumption of the array-type light-emitting device 212.

[0408] Figure 32 This is a diagram showing the operation of the lighting system 100. Figure 32 This illustrates the operation of a lighting system 100 in different temperature environments. The forward voltage V of the LED is shown. FIt exhibits temperature dependence, decreasing as temperature increases. According to this embodiment, the controlled object voltage V can be adaptively set based on temperature. DD Target value V DD（REF） Therefore, electricity consumption can be reduced.

[0409] The above describes the operation of the lighting system 100. Based on this lighting system 100, the data S3B containing the voltage drop V can be... F Relevant information is reflected in the feedback control of the power supply circuit 220 in real time, which can reduce power consumption. Specifically, this is achieved by monitoring the positive voltage V of the light-emitting element 213 during actual operation. F This allows for accurate estimation of the actual minimum operating voltage V of the array-type light-emitting device 212. DD（MIN） The minimum operating voltage V is estimated in this way. DD（MIN） This reflects individual differences or temperature variations in the array-type light-emitting device 212, which are below the value V specified in the standard. DD（SPEC） Therefore, based on the correct minimum operating voltage V DD（MIN） The operating conditions of the power supply circuit 220 are dynamically determined, thereby reducing the power supply voltage V supplied to the array-type light-emitting device 212. DD This can reduce electricity consumption.

[0410] This invention can be used as Figure 30 The invention is not limited to any particular configuration, but rather is understood through block diagrams or circuit diagrams, or by various devices and methods derived from the above description. The following description is not intended to limit the scope of the invention, but rather to aid in understanding the nature or operation of the invention, or to clarify it, by providing more specific structural examples or embodiments.

[0411] (Example 3.1)

[0412] Figure 33 This is a block diagram of the headlight 200A according to Embodiment 3.1. The headlight 200A includes a variable light source 210, a power supply circuit 220A, and a control unit 260.

[0413] The power supply circuit 220A includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power control circuit 225A. The power control circuit 225A includes a feedback circuit 226A, a converter controller 228, and a voltage setting circuit 230.

[0414] The converter controller 228 can use a commercially available DC / DC converter control IC (Integrated Circuit). The converter controller 228 is fed by a feedback voltage V input to the feedback pin FB. FB Approximately the internally generated reference voltage V REFIn this manner, a pulse signal is generated that adjusts at least one of the pulse width or frequency and duty cycle, and feedback control is performed on the DC / DC converter 224 based on the pulse signal.

[0415] In the voltage setting circuit 230, data S3B generated by the array-type light-emitting device 212 is input. Based on the received data S3B, the voltage setting circuit 230 generates a correction voltage V. CMP The feedback circuit 226A operates based on the output voltage V of the DC / DC converter 224. OUT The corresponding controlled object voltage V CNT and correction voltage V CMP Generate feedback voltage V FB This is supplied to the feedback pin FB of the converter controller 228. The feedback voltage V... FB It corresponds to the voltage V of the controlled object. CNT and correction voltage V CMP The signals that change for each are represented by equation (1).

[0416] V FB =K1・V CNT +K2・V CMP …(1)

[0417] K1 is a constant greater than 0, and K2 is a non-zero constant. Here, we set K2 < 0. This feedback signal V is then used by the converter controller 228. FB Approaching the target value V REF The DC / DC converter 224 is controlled in this manner.

[0418] In a stable state where the system has stabilized,

[0419] K1・V CNT +K2・V CMP =V REF

[0420] Therefore, under steady-state conditions, the controlled object voltage V... CNT Stabilize at the target value V CNT（REF） .

[0421] V CNT（REF） = (V REF -K2・V CMP ) / K1…(2)

[0422] In this embodiment 3.1, the controlled object voltage V CNT The voltage V at the power supply terminal VDD of the array-type light-emitting device 212 is... DD .

[0423] The detection terminal SNS of the power supply circuit 220A is connected to the power terminal VDD of the array-type light-emitting device 212 via a detection line (magnetic line) LSNS, which is independent of the power cable 204 (power line LVDD). The input impedance of the feedback circuit 226A is sufficiently high, so no current flows in the detection line LSNS. Therefore, the detection voltage V... SNS The voltage V of the power supply terminal VDD of the array-type light-emitting device 212 DD Equal. The detection voltage V generated at the detection terminal SNS is equal. SNS Voltage V, the object of control CNT The input is fed into the feedback circuit 226A. Therefore, the power supply voltage V... DD Target value V DD（REF） It is expressed as equation (3).

[0424] V DD（REF） = (V REF -K2・V CMP ) / K1…(3)

[0425] That is, by changing the correction voltage V according to data S3B CMP It can change the power supply voltage V DD Target value V DD（REF） .

[0426] The above describes the structure of the 200A headlight. Next, its operation will be explained. Figure 34 yes Figure 33 The waveform diagram of the operation of the 200A headlight. During period T0, the correction voltage V... CMP It is 0V. The power supply voltage V during this period T0 is... DD Stable at

[0427] V DD（REF）＿0 =V REF / K1.

[0428] The output voltage of the DC / DC converter 224 is V. OUT It is more than the power supply voltage V DD Voltage drop V in high power lines LVDD and connectors, etc. DROP The voltage is expressed by equation (4).

[0429] V OUT =V DD +V DROP =V DD +R×I OUT …(4)

[0430] R is the impedance of the power supply line LVDD and the connector. During the illumination period of the headlight 200A, the operating current I of the array-type light-emitting device 212 is... OUT Variation. When observed over a longer time scale, the output current I...OUT The average value varies depending on the light distribution formed by the 200A headlight. Furthermore, when observed on a shorter time scale, the output current I... OUT The instantaneous value varies with the period of PWM control. Figure 34 The figure shows the output current I at longer or shorter time scales. OUT The state of change. In Example 3.1, the power supply voltage V DD Stabilization, output voltage V OUT Based on the output current I OUT And change.

[0431] During period T1, the correction voltage V CMP The value V is set to positive. CMP1 During this period, the power supply voltage V at T1... DD Target value V DD（REF）＿1 for

[0432] V DD（REF）＿1 = (V REF -K2・V CMP1 ) / K1.

[0433] K2 is a negative constant, therefore the power supply voltage V DD Target value V DD（REF） for

[0434] V DD（REF）＿1 = (V REF +|K2|・V CMP1 ) / K1,

[0435] From the target value V during period T0 DD（REF）＿0 Shift towards the positive direction |K2|・V CMP1 / K1 voltage.

[0436] During period T2, if the correction voltage V CMP Set to a higher value V CMP2 Then during this period T2, the power supply voltage V DD Target value V DD（REF）＿2 for

[0437] V DD（REF）＿2 = (V REF -K2・V CMP2 ) / K1,

[0438] For the target value V from period T0 DD（REF）＿0 Shift towards the positive direction |K2|・V CMP2 / K1 voltage.

[0439] The above describes the operation of headlight 200A. Based on headlight 200A, the correction voltage V is changed according to data S3B. CMPThis allows for flexible setting of the voltage V at the power supply terminal VDD of the array-type light-emitting device 212. DD Target value V DD（REF） .

[0440] Next, an example of the structure of the voltage setting circuit 230 and the feedback circuit 226A will be described.

[0441] Figure 35 This is a circuit diagram showing an example of the structure of feedback circuit 226A. Feedback circuit 226A is a subtraction circuit with an amplifier, including resistors R31 to R34 and amplifier OA3. The input-output characteristics of feedback circuit 226A are expressed by equation (5).

[0442] V FB =(R31+R32) / R31×{R34 / (R33+R34)×VCNT-R32 / (R31+R32)×V CMP …(5)

[0443] Comparing equations (1) and (5), we obtain

[0444] K1=(R31+R32) / R31×R34 / (R33+R34)

[0445] K2=-(R31+R32) / R31×R32 / (R31+R32).

[0446] Furthermore, a feedback circuit 226A can be constructed using an amplifier's adder circuit. In this case, K1 > 0, K2 > 0. The correction voltage V... CMP When it is positive, it can be based on the correction voltage V CMP The voltage V of the controlled object CNT The target value is shifted to the lower potential side.

[0447] Figure 36 This is a circuit diagram showing an example of the structure of the voltage setting circuit 230. The voltage setting circuit 230 includes a microcontroller 240, a D / A converter 234, and a buffer 236. The microcontroller 240 sets the voltage setting circuit according to the positive voltage V of the light-emitting element 213. F The relevant data S3B generates the specified correction voltage V. CMP The numerical setting value D CMP By employing a microcontroller 240, the correction voltage V can be adjusted. CMP Implement software control.

[0448] D / A converter 234 converts the set value D generated by microcontroller 240 into an A / D converter. CMP Converted to analog correction voltage V CMP Correction voltage V CMPThe output impedance of the D / A converter 234 is supplied to the feedback circuit 226A via buffer 236. Furthermore, if the output impedance of the D / A converter 234 is sufficiently low, buffer 236 can be omitted. Additionally, if a microcontroller 240 is used that integrates the D / A converter, the D / A converter 234 resides within the microcontroller 240.

[0449] (Example 3.2)

[0450] Figure 37 This is a block diagram of the headlight 200B according to Embodiment 3.2. The structure of the headlight 200B will be described focusing on its differences from Embodiment 3.1. The headlight 200B includes a variable light source 210, a power supply circuit 220B, and a control unit 260. In Embodiment 3.2, the structure of the power supply circuit 220B differs from that of the power supply circuit 220A in Embodiment 3.1.

[0451] The power supply circuit 220B includes an output terminal OUT, a DC / DC converter 224, and a power control circuit 225B. The power control circuit 225B includes a feedback circuit 226B, a converter controller 228, and a voltage setting circuit 230.

[0452] In Example 3.2, the output voltage V of the DC / DC converter 224 OUT For the control object voltage V CNT The output voltage V generated at the output terminal OUT. OUT Voltage V, the object of control CNT The input is fed into the feedback circuit 226B. Therefore, the output voltage V... OUT Target value V OUT（REF） It is represented by equation (6). The feedback circuit 226B, like the feedback circuit 226A in embodiment 3.1, can be a subtraction circuit.

[0453] V OUT（REF） = (V REF -K2・V CMP ) / K1…(6)

[0454] With target value V OUT（REF） For V F（MAX） +V D +α+V DROP The method of generating correction voltage V CMP V DROP It is the voltage drop in the LVDD power supply line and connector, which is V. DROP =I OUT ×R. Because I OUT It changes constantly, therefore the voltage drop V DROP The value can be imagined as the maximum current I OUT（MAX） And the decision.

[0455] Alternatively, as illustrated in Example 3.3, the voltage drop V can also be detected. DROP This makes the actual measured voltage drop V DROP Reflected in the correction voltage V CMP middle.

[0456] The above describes the structure of the 200B headlight. Next, its operation will be explained. Figure 38 yes Figure 37 The waveform diagram of the operation of the 200B headlight. During period T0, the correction voltage V... CMP The voltage is 0V. During this period, the output voltage V of T0 is... OUT Stable at

[0457] V OUT（REF）＿0 =V REF / K1.

[0458] The power supply voltage V supplied to the array-type light-emitting device 212 DD It is compared to the output voltage V OUT Reduce the voltage drop (V) on power lines (LVDD) and connectors. DROP The voltage is expressed by equation (7).

[0459] V DD =V OUT -V DROP =V OUT -R×I OUT …(7)

[0460] R represents the impedance of the power supply line LVDD and the connector. During the illumination of the headlight 200B, the operating current I of the array-type light-emitting device 212 is... OUT It is variable. Therefore, in Example 3.2, the output voltage V OUT Stabilized, power supply voltage V DD Based on the output current I OUT And changes.

[0461] During period T1, the correction voltage V CMP The value V is set to positive. CMP1 During this period, the output voltage V of T1... OUT Target value V OUT（REF）＿1 for

[0462] V OUT（REF）＿1 = (V REF -K2・V CMP1 ) / K1 .

[0463] Since K2 is a negative constant, the output voltage V OUT Target value V OUT（REF） for

[0464] VOUT（REF）＿1 = (V REF +|K2|・V CMP1 ) / K1,

[0465] For the target value V from period T0 OUT（REF）＿0 Shift towards the positive direction |K2|・V CMP1 / K1 voltage.

[0466] During period T2, the correction voltage V will be... CMP Set to a higher value V CMP2 During this period T2, the output voltage V OUT Target value V OUT（REF）＿2 for

[0467] V OUT（REF）＿2 = (V REF -K2・V CMP2 ) / K1,

[0468] For the target value V from period T0 DD（REF）＿0 Shift in the positive direction |K2|・V CMP2 / K1 voltage.

[0469] The above describes the operation of headlight 200B. Based on headlight 200B, the calibration voltage V can be used... CMP The output voltage V of the DC / DC converter 224 can be flexibly set. OUT This allows for flexible setting of the voltage V at the power supply terminal VDD of the array-type light-emitting device 212. DD .

[0470] (Example 3.3)

[0471] Figure 39 This is a block diagram of the headlight 200C according to Embodiment 3.3. The structure of the headlight 200C will be described focusing on the differences from Embodiment 3.2.

[0472] The headlight 200C includes a variable light source 210, a power supply circuit 220C, and a control unit 260. In embodiment 3.3, the structure of the power supply circuit 220C differs from that of the power supply circuit 220B in embodiment 3.2.

[0473] The structure of power supply circuit 220C is described below. Power supply circuit 220C includes output terminal OUT, detection terminal SNS, DC / DC converter 224, and power control circuit 225C.

[0474] The power control circuit 225C includes a feedback circuit 226C, a converter controller 228, and a voltage setting circuit 230.

[0475] In the feedback circuit 226C, the voltage V, which is the controlled object, is...CNT Input and output voltage V OUT Furthermore, the power supply voltage V is input to the feedback circuit 226C via the detection line LSNS. DD Furthermore, the correction voltage V generated by the input voltage setting circuit 230 is fed into the feedback circuit 226C. CMP .

[0476] Feedback circuit 226C is based on three voltages V OUT V SNS V CMP Generate feedback voltage V FB Feedback circuit 226C is based on V OUT and V SNS The differential voltage drop V in the LVDD power line is detected. DROP =V OUT -V SNS .

[0477] The feedback voltage V generated by the feedback circuit 226C FB It is represented by equation (8).

[0478] V FB =K1・V OUT +K2・V CMP +K3・V DROP …(8)

[0479] The above describes the structure of the headlight 200C. In this headlight 200C, the controlled voltage is the output voltage V. OUT Target value V OUT（REF） It is represented by equation (9).

[0480] V OUT（REF） = (V REF -K2・V CMP -K3·V DROP ) / K1…(9)

[0481] If K2 < 0 and K3 < 0, then it is

[0482] V OUT（REF） = (V REF +|K2|・V CMP +|K3|·V DROP ) / K1…(9') .

[0483] When |K3| = K1,

[0484] V OUT（REF） = (V REF +|K2|・V CMP ) / K1+V DROP …(9'')

[0485] According to Example 3.3, the actual measured voltage drop V can be used as a basis for calculation. DROP This makes the output voltage V OUT Target value V OUT（REF） Ideally, this can reduce power consumption. By appropriately setting the gain K3, the voltage drop of the ground wire LGND can also be corrected.

[0486] Figure 40 This is a functional block diagram of feedback circuit 226C. Feedback circuit 226C can contain three subtraction circuits SUB1 to SUB3. Subtraction circuit SUB1 draws voltage from the output voltage V. OUT Subtract the detection voltage V SNS Calculate the voltage drop V DROP The subtraction circuit SUB2 draws voltage from the output voltage V. OUT Subtract voltage drop V DROP The subtraction circuit SUB3 receives the output voltage V from the subtraction circuit SUB2. OUT -V DROP Subtract the correction voltage V CMP The order of subtraction can be changed.

[0487] (Example 3.4)

[0488] Figure 41 This is a circuit diagram of the headlight 200D according to Embodiment 3.4. The headlight 200D includes a variable light source 210, a power supply circuit 220D, and a control unit 260.

[0489] The structure of power supply circuit 220D is described. Power supply circuit 220D includes output terminal OUT, detection terminal SNS, DC / DC converter 224, and power control circuit 225D.

[0490] The power control circuit 225D includes a feedback circuit 226D, a converter controller 228D, and a voltage setting circuit 230D. In this embodiment, the converter controller 228D has a reference voltage setting pin REF, which can set the voltage according to the reference signal S input to the reference voltage setting pin REF. REF Set the reference voltage V REF The converter controller 228D receives the reference signal S. REF As a digital signal, a reference voltage V can be generated through an internal voltage source. REF Alternatively, the converter controller 228D can receive an analog reference signal S. REF It is directly used as the internal reference voltage V. REF The converter controller 228D uses the voltage V of the feedback pin FB. FB Approaching the reference signal S REF The reference voltage V REFThe DC / DC converter 224 is controlled by feedback in this manner.

[0491] The voltage setting circuit 230D generates a reference signal S based on the data S3B. REF The reference voltage setting pin REF is supplied to the converter controller 228D. Reference signal S REF In the case of analog voltage, the voltage setting circuit 230D can be used with... Figure 36 Similarly, the correction voltage V is constructed. CMP Replace with reference signal S REF That's it. Reference signal S REF In the case of a digital signal, the voltage setting circuit 230D can be controlled solely by... Figure 36 The microcontroller 240 is configured to set the value D. CMP Replace with reference signal S REF That's all.

[0492] Feedback circuit 226D generates and controls the object voltage V CNT The corresponding feedback voltage V FB The feedback pin FB is supplied to the converter controller 228D.

[0493] Similar to Example 3.2, the controlled object voltage V CNT It can also be the output voltage V OUT At this time, the feedback voltage V FB It is represented by equation (10).

[0494] V FB =K1・V OUT …(10)

[0495] Similar to Example 3.1, the power supply circuit 220D and the variable light source 210D can be connected via the detection line LSNS to transmit the detection voltage V. SNS (=V) DD Voltage V, as the controlled object CNT The feedback voltage V at this time FB It is represented by equation (11).

[0496] V FB =K1・V SNS =K1・V DD …(11)

[0497] Similar to Example 3.3, the output voltage V can be... OUT Voltage V, the object of control CNT The voltage drop V in the LVDD power line will be corrected. DROP The voltage is used as the feedback voltage V FB The feedback voltage V at this time FBIt is represented by equation (12).

[0498] V FB =K1・V OUT +K3・V DROP …(12)

[0499] As illustrated in Example 3.3, the voltage drop V DROP By connecting the power circuit 220D and the variable light source 210D via the detection line LSNS, V is calculated. OUT and V SNS It can be obtained by the difference.

[0500] According to Example 3.4, the same effect as in Examples 3.1 to 3.3 was obtained.

[0501] In the above embodiments, the microcontroller may have the following functions. Figure 42 This is a block diagram showing the structure of the microcontroller 240.

[0502] (Anomaly detection function)

[0503] The microcontroller 240 can acquire the voltage V of the controlled object. CNT and the target value V based on data S3B CNT（REF） The error ΔV. The controlled object voltage V cannot be detected by the converter controller 228. CNT Departure from the target value V CNT（REF） In this situation, the voltage V of the controlled object is monitored by the microcontroller 240. CNT and target value V CNT（REF） The error can be used to detect abnormal states (fault determination).

[0504] The microcontroller 240 has multiple analog input pins AN1 to ANX, a multiplexer MUX, an A / D converter 242, a processor (core) 244, and an interface circuit 246.

[0505] The input of the built-in A / D converter 242 can be switched via a multiplexer MUX, converting the voltage of any analog input pin into a digital value. Furthermore, the interface circuit 246 can receive data S3B. In addition to external analog voltages, the internal reference voltage or power supply voltage of the microcontroller 240 can be input to the A / D converter 242.

[0506] Controlled object voltage V CNT The input is to one of the analog input pins AN of the microcontroller 240. As described above, the controlled object voltage V CNT It can be the output voltage V OUT It can also be the power supply voltage V. DDThe A / D converter 242 generates the controlled object voltage V. CNT The numerical value Dx.

[0507] Processor 244 executes a software program to generate a set value D corresponding to the data S3B received by interface circuit 246. CMP (or reference signal S) REF ), output from the digital output pin DOUT.

[0508] Furthermore, the processor 244 calculates the voltage V of the controlled object based on the data S3B. CNT Target value V CNT（REF） The processor 244 calculates the difference between the digital value Dx obtained by the A / D converter 242 and the calculated digital value Dy, and compares it with a threshold. When Dx - Dy exceeds the threshold, the processor 244 determines an exception. During exception determination, the processor 244 can output a flag indicating an exception from the general purpose output pin GPIO.

[0509] In one embodiment, when the microcontroller 240 determines an abnormality, the set value D is... CMP (Reference signal S) REF The voltage V of the controlled object can be fixed to a specified value. By setting the specified value higher, the voltage V of the controlled object can be forced to be set higher. CNT Target value V CNT（REF） The voltage increases. Thus, under abnormal conditions, a higher voltage is forcibly supplied to the array-type light-emitting device, which can maintain the light and function as a fault protection mechanism.

[0510] (A / D converter calibration)

[0511] The accuracy of the A / D converter 242 built into the microcontroller 240 is usually not very high. A lower accuracy A / D converter 242 can lead to poor performance of the aforementioned fault protection function. Therefore, the following processing can be performed during the manufacturing or inspection process of the headlight 200.

[0512] Figure 43 This diagram illustrates the calibration of the microcontroller's built-in A / D converter. An analog signal with a known voltage level is input to the analog input pin AN, and its voltage level is switched between at least two values, AV and BV. Furthermore, the A / D converter 242 converts the two voltage levels AV and BV into digital values ​​Aad and Bad.

[0513] Furthermore, the difference Δad between the digital values ​​Aad and Bad is calculated. The difference ΔV between the two analog values ​​AV and BV is divided by the difference Δad between the digital values, and the result ΔV / Δad is non-volatilely stored as the correction parameter α. Additionally, the following steps are performed: Figure 43The offset value ZEROad is stored non-volatilely as the correction parameter β. The offset value ZEROad can be obtained from the measurement results of two points, or by inputting 0V into the A / D converter 242.

[0514] After the headlight 200 leaves the factory, the processor 244 of the microcontroller 240 uses parameters α and β to correct the output x of the A / D converter 242. The corrected actual value y can be obtained by the following formula.

[0515] y = (x - β) × α

[0516] The microcontroller 240 can retain information useful for analyzing the headlight 200 or developing new products as a log. Below are examples of information that the microcontroller 240 should retain as a log.

[0517] Temperature information

[0518] The microcontroller 240 retains temperature information obtained from peripheral or built-in temperature sensors as a log. The temperature information may include the maximum temperature, minimum temperature, and average temperature.

[0519] • Power supply voltage information

[0520] The microcontroller 240 retains information on various power supply voltages supplied externally and / or generated by the built-in power supply circuitry as a log. Voltage information may include maximum voltage, minimum voltage, and average voltage.

[0521] • Measurement information during anomaly detection

[0522] When an anomaly is detected, the microcontroller 240 retains the time and type of the anomaly as a history record. At the same time, it retains accompanying information such as the temperature and power supply voltage at the time of the anomaly as a log.

[0523] • Information on cumulative operating time

[0524] The microcontroller 240 records information on the cumulative operating time since the factory shipment. The cumulative operating time may include information such as the cumulative operating time of the power supply circuit 220, including the cumulative operating time of the variable light source 210 of the array-type light-emitting device 212, and other information such as the various power supply voltages generated by external supply and / or built-in power supply circuits.

[0525] Explain variations related to implementation method 3.

[0526] (Variation 3.1)

[0527] Figure 44This diagram shows the headlight 200 of Modification 3.1. In the preceding description, the variable light source 210 has one array-type light-emitting device 212, but the variable light source 210 can have multiple array-type light-emitting devices 212. In this case, the power supply circuit 220 can be modularized (also called power supply unit 222), and multiple power supply units 222 can be provided corresponding to the multiple array-type light-emitting devices 212. The output terminal of each power supply unit 222 is connected to the power supply terminal of the corresponding array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, as needed, a detection line LSNS can be provided for each pair of power supply unit 222 and array-type light-emitting device 212. In this modification, the microcontroller 240 can be common to multiple power supply units.

[0528] In this variation 3.1, the variable light distribution light source 210 is configured as multiple array-type light-emitting devices 212, each with its own independent power supply terminal. Furthermore, a power supply unit 222 is provided for each array-type light-emitting device 212, and the array-type light-emitting device 212 and the power supply unit are connected one-to-one via power cables. This allows the current flowing in the variable light distribution light source 210 to be distributed across multiple DC / DC converters in the system, reducing the impact of voltage drop in each DC / DC converter and improving load responsiveness. In addition, the options for structural components, power cables, and connectors of the DC / DC converters increase, enhancing design freedom.

[0529] (Variation 3.2)

[0530] Figure 45 This diagram shows the headlight 200 of Modified Example 3.2. The array-type light-emitting device 212 may consist of multiple internal light-emitting pixels divided into multiple segments SEG1 to SEGn, with multiple power supply terminals VDD corresponding to each segment SEG1 to SEGn. In the power supply circuit 220, multiple power supply units 222_1 to 222_n are provided corresponding to the multiple power supply terminals VDD. The output terminal OUT of each power supply unit 222 is connected to the corresponding power supply terminal VDD of the array-type light-emitting device 212 via a separate power cable LVDD. Furthermore, a detection line LSNS may be provided for each power supply unit 222 as needed.

[0531] In this variation 3.2, the current flowing in the variable light source 210 can be distributed among multiple DC / DC converters in the system, achieving the same effect as in variation 3.1.

[0532] (Variation 3.3)

[0533] The power supply unit 222 can be constructed using a phase-shift converter. By employing a phase-shift converter, the output voltage V can be reduced compared to a single-phase converter. OUTiOr output current I OUTi The ripple can be reduced, or efficiency can be improved. Furthermore, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I of the power supply unit 222... OUTi It will change rapidly depending on the illumination rate of multiple pixel circuits, but by using a phase-shift converter, the tracking (responsiveness) to load changes can be improved.

[0534] (Variation 3.4)

[0535] This describes a scenario where the power supply circuit 220 or the control unit 260 is built into the headlight 200, but one or both of them can be located outside the headlight body of the headlight 200. Since the variable light source 210 is a heat-generating element, it is advantageous from a thermal design point of view to have the control unit 260 positioned away from the variable light source 210 within the vehicle interior to avoid heat generation.

[0536] (Variation 3.5)

[0537] The power control circuit 225 can also receive the data S3 output from the interface circuit 216 directly without going through the control unit 260.

[0538] (Variation 3.6)

[0539] The power control circuit 225 can ignore the on / off state of multiple pixel circuits (PIX) and rely on the positive voltage V of all pixels. F1 ~V Fn The maximum value determines the target value. The power control circuit 225 can be used in multiple pixel circuits (PIX) to determine the target value based on the positive voltage V of the actually lit pixel. F The maximum value determines the target value.

[0540] (Variation 3.7)

[0541] Array-type light-emitting devices can also pre-determine the forward voltage V of multiple internal light-emitting elements. F The maximum value is V F（MAX） It is stored in internal non-volatile memory. Positive voltage V F（MAX） It could be the maximum value across all pixels and all temperature ranges. Alternatively, it could store the positive voltage V for each temperature range. F（MAX） Send data containing the maximum value corresponding to the current temperature.

[0542] The embodiments only illustrate the principles and applications of the present invention. Various modifications to the word order or configurations may be made to the embodiments without departing from the spirit and scope of the present invention as defined in the claims.

[0543] Industrial availability

[0544] This disclosure relates to vehicle lighting fixtures.

[0545] Explanation of reference numerals in the attached figures

[0546] 100…Lighting system, 102…Battery, 104…Host controller, 200…Headllight, 202…Connection unit, 204…Power cable, 206…Connector, 210…Variable light source, 212…Array type light-emitting device, PIX…Pixel circuit, 213…Light-emitting element, 214…Current source, 216…Interface circuit, 220…Power supply circuit, 222…Power supply unit, 224…DC / DC converter, 225…Power control circuit, 226…Feedback circuit, 228…Converter controller, 230…Voltage setting circuit, 234…D / A converter, 236…Buffer, 240…Microcontroller, 260…Control unit.

Claims

1. A lighting system, characterized in that, include: Variable light source with light distribution, including array-type light-emitting devices, and The power supply circuit supplies power to the array-type light-emitting device; The array-type light-emitting device includes multiple pixel circuits electrically connected in parallel and arranged in a matrix in space. Each pixel circuit includes a light-emitting element connected in series and a current source. The array-type light-emitting device is configured to acquire data related to the voltage drop of the multiple light-emitting elements included in the multiple pixel circuits and transmit it to the outside. The power supply circuit includes: A DC / DC converter, the output of which is connected to the array-type light-emitting device via a power cable, and The power control circuit controls the DC / DC converter in such a way that the voltage of the controlled object is close to a target value corresponding to the data.

2. The lighting system according to claim 1, characterized in that, The target value is based on the maximum voltage drop of the plurality of light-emitting elements.

3. The lighting system according to claim 1 or 2, characterized in that, The power control circuit includes: A voltage setting circuit generates a correction voltage corresponding to the data; The feedback circuit generates a feedback voltage based on the controlled object voltage and the correction voltage; and The converter controller receives the feedback voltage at the feedback pin and controls the DC / DC converter in such a manner that the feedback voltage is close to a specified reference voltage.

4. The lighting system according to claim 3, characterized in that, The voltage setting circuit includes: A microcontroller that generates a set value of a number corresponding to the data; and The D / A converter converts the set value into an analog correction voltage.

5. The lighting system according to claim 1, characterized in that, The power control circuit includes: The voltage setting circuit generates a reference signal corresponding to the data; and The converter controller has a feedback pin that receives a feedback voltage corresponding to the voltage of the controlled object, and a reference voltage setting pin that receives the reference signal, and controls the DC / DC converter such that the feedback voltage is close to a reference voltage based on the reference signal.

6. The lighting system according to claim 5, characterized in that, The voltage setting circuit includes a microcontroller that generates a set value corresponding to the data, wherein the reference voltage corresponds to the set value.

7. The lighting system according to claim 1 or 2, characterized in that, The power supply circuit also includes a detection terminal, which is connected to the power terminal of the array-type light-emitting device via a detection line independent of the power cable. The voltage of the controlled object is the detection voltage generated at the detection terminal.

8. The lighting system according to claim 1 or 2, characterized in that, The voltage of the controlled object is the output voltage of the DC / DC converter.

9. The lighting system according to claim 1 or 2, characterized in that, It also includes a control unit, which is connected to the interface circuit of the array-type light-emitting device, and controls the on / off state of the plurality of pixel circuits of the array-type light-emitting device. The power control circuit receives the data via the control unit.

10. The lighting system according to claim 4 or 6, characterized in that, The microcontroller acquires the voltage of the controlled object and the error between it and the target value based on the data.

11. The lighting system according to claim 10, characterized in that, The microcontroller determines an anomaly when the error between the controlled object voltage and the target value exceeds a predetermined threshold.

12. The lighting system according to claim 11, characterized in that, When the microcontroller determines that the abnormality is true, the set value is fixed at a predetermined value.

13. The lighting system according to claim 4 or 6, characterized in that, The microcontroller stores the history of the data.

14. The lighting system according to claim 4 or 6, characterized in that, It also includes a temperature sensor, and the microcontroller stores information related to the temperature acquired by the temperature sensor.

15. A lighting system, characterized in that, include: An array-type light-emitting device comprises multiple pixel circuits electrically connected in parallel and arranged in an array in space. The power supply circuit supplies power to the array-type light-emitting device, and The connection unit includes a power cable connecting the power supply circuit and the array-type light-emitting device; The power supply circuit includes: The output of the DC / DC converter is connected to the array-type light-emitting device via the connection unit, and The power control circuit acquires the voltage drop of the connection unit, sets a target value based on the voltage drop of the connection unit, and controls the DC / DC converter so that the output voltage of the DC / DC converter is close to the target value.

16. The lighting system according to claim 15, characterized in that, The power supply circuit also includes a current sensor that generates a current detection signal corresponding to the output current of the DC / DC converter. The power control circuit sets the target value based on the current detection signal.

17. The lighting system according to claim 15, characterized in that, The power supply circuit also includes a detection terminal, which is connected to the power terminal of the array-type light-emitting device via a detection line independent of the power cable. The power control circuit obtains the voltage drop of the connection unit based on the difference between the output voltage of the DC / DC converter and the detection voltage of the detection terminal.

18. The lighting system according to any one of claims 15 to 17, characterized in that, The power control circuit includes: The feedback circuit generates a feedback voltage based on the output voltage of the DC / DC converter and a correction voltage corresponding to the voltage drop of the connection unit; and The converter controller receives the feedback voltage at the feedback pin and controls the DC / DC converter in such a manner that the feedback voltage is close to a specified reference voltage.

19. The lighting system according to any one of claims 15 to 17, characterized in that, The power control circuit includes: A voltage setting circuit generates a reference signal corresponding to the voltage drop of the connection unit; and The converter controller has a feedback pin that receives a feedback voltage corresponding to the output voltage and a reference voltage setting pin that receives the reference signal, and controls the DC / DC converter such that the feedback voltage is close to a reference voltage based on the reference signal.

20. A power supply circuit for supplying power to an array-type light-emitting device, the array-type light-emitting device comprising a plurality of pixel circuits electrically connected in parallel and arranged in an array in space, characterized in that... include: A DC / DC converter, the output of which is connected to the array-type light-emitting device via a connection unit including a power cable; A current sensor generates a current detection signal corresponding to the output current of the DC / DC converter; A converter controller has a feedback pin to control the DC / DC converter in such a way that the feedback voltage input to the feedback pin is close to a specified reference voltage. as well as The feedback circuit supplies a feedback signal corresponding to the output voltage of the DC / DC converter and the current detection signal to the feedback pin of the converter controller.

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