Vehicle lighting system, and power circuit

Abstract

To provide stable power supply to an array-type light-emitting device.SOLUTION: An array type light emitting device 212 includes a plurality of pixel circuits PIX electrically connected in parallel and spatially arranged in a matrix. A power supply circuit 220 supplies power to the array type light emitting device 212. Connection means 202 connects the power supply circuit 220 and the array type light emitting device 212. The output of a DC / DC converter 224 is connected to the array type light emitting device 212 via the connection means 202. The power supply control circuit 225 acquires a voltage drop across the connection means 202, sets a target value according to the voltage drop across the connection means 202, and controls the DC / DC converter 224 such that the output voltage VOUT of the DC / DC converter 224 approaches the target value.SELECTED DRAWING: Figure 21

Description

[Technical field]

[0001] The present invention relates to a vehicle lamp. [Background technology]

[0002] Vehicle lamps are generally capable of switching between low beam and high beam. Low beam illuminates the vicinity of the vehicle with a predetermined illuminance, and light distribution regulations are established so as not to cause glare to oncoming vehicles or preceding vehicles, and is mainly used when driving in urban areas. On the other hand, high beam illuminates a wide range and distant area ahead with a relatively high illuminance, and is mainly used when driving at high speed on roads with few oncoming vehicles or preceding vehicles. Therefore, high beam has better visibility for the driver than low beam, but has the problem of causing glare to drivers of vehicles and pedestrians in front of the vehicle.

[0003] In recent years, ADB (Adaptive Driving Beam) has been proposed, which dynamically and adaptively controls the high beam light distribution pattern based on the conditions around the vehicle. ADB technology detects the presence or absence of preceding vehicles, oncoming vehicles, and pedestrians ahead of the vehicle, and reduces the glare given to vehicles or pedestrians by dimming or turning off the areas corresponding to the vehicles or pedestrians.

[0004] A bypass type configuration that combines an LED (light emitting diode) string and a bypass circuit has been put to practical use as an ADB lamp. Figure 1 is a block diagram of a bypass type lamp 1R.

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

[0006] The constant current driver 70 generates a drive current I LED and supplies it to the LED string 50. The bypass circuit 80 includes a plurality of switches SW1 to SWn provided in parallel with the plurality of LEDs 52_1 to 52_n.

[0007] When a switch SWi (1≦i≦n) in the bypass circuit 80 is in an off state, the current I generated by the current source 72 LED flows to the LED 52_i, so that the LED 52_i is turned on. When the switch SWi is in the on state, the current I LED Since the current is bypassed to the switch SWi, the LED52_i is turned off.

[0008] On the virtual vertical screen 40, a light distribution pattern 42 is formed in response to the on / off states of the multiple bypass switches SW1 to SWn.

[0009] In the bypass type lamp of FIG. 1, the number n of LEDs 52, that is, the number of divisions of the regions that can be controlled to be on and off, is several to a dozen or so at most. In order to realize a larger number of divisions, an ADB lamp of an LED (light-emitting diode) array type has been proposed. FIG. 2 is a block diagram of an ADB lamp 1S of an LED array type. 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 a plurality of LEDs 12 arranged in an array and an LED driver 14 that drives the plurality of LEDs 12, and is a device (called an array type light-emitting device) that is packaged in one package. One pixel (also called a pixel circuit) is composed of the LED 12 and the LED driver 14, and the LED driver 14 includes a current source (switch) connected in series with the LED 12, and switches each pixel on (lighting) and off (lighting out) by controlling the on / off of the current source.

[0010] The power supply circuit 30 supplies a power supply voltage V DDThe power supply circuit 30 includes a DC / DC converter 32 and a controller 34 for the DC / DC converter 32. The controller 34 receives the output voltage V OUT Feedback voltage V based on FB is fed back, and the feedback voltage V FB is the target value V REF The DC / DC converter 32 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0011] The light distribution controller 20 generates a control signal that specifies whether a plurality of pixels are on or off, and transmits it to the LED array device 10. The emitted beam from the LED array device 10 passes through an optical system (not shown) and is irradiated onto a virtual vertical screen 40. A light distribution pattern 42 corresponding to the on and off states of the plurality of light-emitting elements 12 is formed on the virtual vertical screen 40. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2018-172038 A Summary of the Invention [Problem to be solved by the invention]

[0013] Problem 1. As a result of examining the ADB lamp 1S in FIG. 2, the present inventor has come to recognize the following problem.

[0014] In the circuit of FIG. 2, multiple (N) pixel circuits are connected in parallel, so the output current I OUT is at most I OUT(MAX) =I LED ×N. Currently, LED array devices 10 having a pixel number N ranging from several thousand to more than 10,000 are being developed.

[0015] For example, I LED = 10mA, and the number of LEDs N = 3000, the maximum output current I OUT(MAX) reaches 30A.

[0016] The power cable 16 and the connector have a DC resistance component R, and when a large current flows, a voltage drop V DROP (=R×I OUT The voltage at the output terminal of the power supply circuit 30 is V OUT Then, the power supply voltage (also called the load input voltage) V DD teeth, V DD =V OUT -R×I OUT In order for the pixel circuit to operate normally, the load input voltage V DD V DD(MIN) =Vf+V SAT +α. Vf is the forward voltage of the LED, and V SAT is the voltage across the LED driver 14 (the minimum operating voltage), and α is the voltage margin.

[0017] Therefore, in the power supply circuit 30, the output voltage V OUT The target voltage V OUT(REF) of, V OUT(REF) >V DD(MIN) +R×I OUT The controller 34 must be designed to satisfy the following:

[0018] 3(a) and (b) are waveform diagrams of the ADB lamp 1S in FIG. 2. The output current I OUT is 0 to I OUT(MAX) The maximum output current I OUT(MAX) Assuming that the output voltage is V OUT The target value of V OUT(REF) of, V OUT(REF) =V DD(MIN) +R×I OUT(MAX) In this case, I OUT When V is ≒0, the load input voltage V DD is the minimum voltage V DD(MIN) It is larger than (V DD -VDD(MIN) )×I OUT This is a waste of power. The target value V OUT(REF) If the load input voltage V DD However, the minimum operating voltage V DD(MIN) This increases the likelihood of the light falling below this threshold, causing flickering or going out.

[0019] Also, as shown at time t0 in FIG. 3(a), the output current I OUT When there is a sudden change in the output voltage V OUT The power supply voltage V DD The power supply voltage V DD is the minimum operating voltage V DD(MIN) If it falls below this, flickering will occur.

[0020] Issue 2. The commercially available LED array device 10 has a minimum operating voltage V DD(MIN) is specified. The minimum operating voltage V DD(MIN) is based on the minimum operating voltage of the pixel, specifically, the forward voltage V F and the voltage drop of the current source V D It is based on the sum of.

[0021] The minimum operating voltage for each pixel is affected by process variations, and therefore differs for each pixel in the same chip of the LED array device 10 and for each individual LED array device 10. DD(MIN) is also affected by temperature. Generally, the specified value V DD(SPEC) takes into consideration individual variations and temperature fluctuations of the LED array device 10, and the minimum operating voltage V DD(MIN) Therefore, the operating conditions of the power supply circuit 30 are set to a value V DD(SPEC) If the LED array device 10 is designed based on this, an excessive voltage will be supplied to many LED array devices 10 that are actually used, which will result in increased power consumption.

[0022] An aspect of the present disclosure has been made in consideration of problem 1, and one of its exemplary objectives is to provide a lighting system capable of stably supplying power to an array-type light-emitting device.

[0023] An aspect of the present disclosure has been made in consideration of problem 1, and one of its exemplary objectives is to provide a lighting system that can reduce the power consumption of an array-type light-emitting device. [Means for solving the problem]

[0024] 1. An aspect of the present disclosure relates to a lighting system. The lighting system includes an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and spatially arranged in a matrix, and a power supply circuit that supplies 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 supply control circuit that sets a target value according to a light distribution pattern and controls the DC / DC converter so that a controlled voltage approaches the target value.

[0025] 2. An aspect of the present disclosure relates to a lighting system. The lighting system includes an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and spatially arranged in a matrix, a power supply circuit that supplies power to the array-type light-emitting device, and a connection means including a power cable that connects 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 supply control circuit that obtains a voltage drop in the power cable, sets a target value according to the voltage drop in the power cable, and controls the DC / DC converter so that the output voltage of the DC / DC converter approaches the target value.

[0026] 3. An aspect of the present disclosure relates to a lighting system. The lighting system includes a variable light distribution light source including an array-type light-emitting device, and a power supply circuit that supplies power to the array-type light-emitting device. The array-type light-emitting device includes a plurality of pixel circuits. The pixel circuits are electrically connected in parallel, spatially arranged in a matrix, and each includes a light-emitting element and a current source that are connected in series. The array-type light-emitting device is configured to acquire data related to a voltage drop of a plurality of light-emitting elements included in the plurality of pixel circuits, and transmit the data to the outside. 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 supply control circuit that controls the DC / DC converter so that the controlled voltage approaches a target value according to the data.

[0027] In addition, any combination of the above components, and mutual substitution of the components and expressions of the present disclosure between methods, devices, systems, etc. are also valid aspects of the present disclosure. Effect of the Invention

[0028] According to an aspect of the present disclosure, it is possible to reduce power consumption, and it is possible to stably supply power to an array-type light-emitting device. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a block diagram of a bypass type lamp. [Diagram 2] This is a block diagram of an LED array type ADB lamp. [Diagram 3] 3(a) and (b) are operational waveform diagrams of the ADB lamp of FIG. [Figure 4] 1 is a block diagram of a lighting system according to a first embodiment. [Diagram 5] 5 is a diagram showing an operation according to a first control example of the lighting system of FIG. 4. [Figure 6] 5 is a diagram showing an operation according to a second control example of the lighting system of FIG. 4. [Figure 7]7(a) and (b) are diagrams illustrating the control of the target value based on the forward voltage VF. [Figure 8] FIG. 4 is a diagram illustrating the operation of the lighting system. [Figure 9] FIG. 1 is a block diagram of a headlamp according to Example 1.1. [Figure 10] FIG. 10 is an operational waveform diagram of the headlamp of FIG. [Figure 11] FIG. 2 is a circuit diagram showing a configuration example of a feedback circuit. [Figure 12] FIG. 2 is a circuit diagram showing a configuration example of a voltage setting circuit. [Figure 13] FIG. 1 is a block diagram of a headlamp according to Example 1.2. [Figure 14] 11 is an operational waveform diagram of a headlamp employing control example 2. FIG. [Figure 15] FIG. 11 is an operational waveform diagram of a headlamp employing a control example 4. [Figure 16] FIG. 11 is a block diagram of a headlamp according to Example 1.3. [Figure 17] FIG. 2 is a functional block diagram of a feedback circuit. [Figure 18] FIG. 11 is a circuit diagram of a headlamp according to Example 1.4. [Figure 19] FIG. 13 is a diagram showing a headlamp according to modification 1.1. [Figure 20] FIG. 13 is a diagram showing a headlamp according to modified example 1.2. [Figure 21] FIG. 11 is a block diagram of a lighting system according to a second embodiment. [Figure 22] 22A to 22D are diagrams illustrating the operation of the lighting system of FIG. 21. [Figure 23] FIG. 2 is a block diagram of a headlamp according to Example 2.1. [Figure 24] FIG. 2 is a circuit diagram showing a configuration example of a feedback circuit. [Diagram 25] FIG. 11 is a block diagram of a headlamp according to Example 2.2. [Figure 26] FIG. 11 is a block diagram of a headlamp according to Example 2.3. [Figure 27]FIG. 11 is a block diagram of a headlamp according to Example 2.4. [Figure 28] FIG. 13 is a diagram showing a headlamp according to modification 2.1. [Figure 29] FIG. 13 is a diagram showing a headlamp according to modified example 2.2. [Diagram 30] FIG. 11 is a block diagram of a lighting system according to a third embodiment. [Diagram 31] 31(a) and (b) are diagrams showing the operation of the lighting system. [Diagram 32] FIG. 4 is a diagram illustrating the operation of the lighting system. [Diagram 33] FIG. 3 is a block diagram of a headlamp according to Example 3.1. [Diagram 34] FIG. 34 is an operational waveform diagram of the headlamp of FIG. 33. [Diagram 35] FIG. 2 is a circuit diagram showing a configuration example of a feedback circuit. [Diagram 36] FIG. 2 is a circuit diagram showing a configuration example of a voltage setting circuit. [Figure 37] FIG. 11 is a block diagram of a headlamp according to Example 3.2. [Figure 38] FIG. 38 is an operational waveform diagram of the headlamp of FIG. 37. [Figure 39] FIG. 11 is a block diagram of a headlamp according to Example 3.3. [Diagram 40] FIG. 2 is a functional block diagram of a feedback circuit. [Diagram 41] FIG. 11 is a circuit diagram of a headlamp according to Example 3.4. [Diagram 42] FIG. 2 is a block diagram showing a configuration of a microcontroller. [Diagram 43] FIG. 1 is a diagram for explaining calibration of an A / D converter built into a microcontroller. [Diagram 44] FIG. 13 is a diagram showing a headlamp according to modified example 3.1. [Diagram 45] FIG. 13 is a diagram showing a lighting system according to Modification 3.2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] A summary of some exemplary embodiments of the present disclosure will be described. This summary is intended to provide a simplified overview of some concepts of one or more embodiments for a basic understanding of the embodiments as a prelude to the detailed description that follows, and is not intended to limit the scope of the invention or disclosure. This summary is not intended to be an exhaustive overview of all possible embodiments, nor is it intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may be used to refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed in this specification.

[0031] 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 spatially arranged in a matrix, 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 supply control circuit that sets a target value according to a light distribution pattern and controls the DC / DC converter so that a controlled voltage approaches the target value.

[0032] The current flowing through the array-type light-emitting device changes according to the light distribution pattern. Therefore, by dynamically and adaptively changing the target value of the controlled 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. It is also possible to reduce unnecessary power consumption.

[0033] The power supply control circuit may change the target value prior to changing the light distribution pattern.

[0034] The lighting system according to an embodiment may further include a control unit that controls the pixel circuits according to the light distribution pattern. The power supply control circuit may set the target value according to first data related to the light distribution pattern received from the control unit.

[0035] In one embodiment, the power supply control circuit may include a voltage setting circuit that generates a correction voltage according to the 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 a DC / DC converter so that the feedback voltage approaches a predetermined reference voltage. When a converter controller whose internal reference voltage cannot be set externally is used, the target value of the controlled voltage can be set by shifting the feedback voltage according to the correction voltage.

[0036] In one embodiment, the voltage setting circuit may include a microcontroller that generates a digital setting value according to the light distribution pattern, and a D / A converter that converts the setting value into an analog correction voltage, which allows the target value of the controlled voltage to be software-controlled.

[0037] In one embodiment, the power supply control circuit may include a voltage setting circuit that generates a reference signal according to the light distribution pattern, a feedback pin that receives a feedback voltage according to the voltage to be controlled, and a converter controller that has a reference voltage setting pin that receives the reference signal and controls the DC / DC converter so that the feedback voltage approaches a reference voltage based on the reference signal. When a converter controller whose internal reference voltage can be controlled from the outside is used, the target value of the voltage to be controlled can be set by directly controlling the internal reference voltage of the converter controller according to data.

[0038] In one embodiment, the voltage setting circuit includes a microcontroller that generates a digital set value corresponding to the light distribution pattern, and the reference voltage may correspond to the set value, thereby enabling software control of the target value of the controlled voltage.

[0039] 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 independent of the power cable. The voltage to be controlled may be a detection voltage generated at the detection terminal. With this configuration, a feedback loop is formed so that an appropriate power supply voltage is supplied to the power supply terminal of the array type light-emitting device. Therefore, unnecessary power consumption can be reduced.

[0040] In one embodiment, the controlled voltage may be the output voltage of the DC / DC converter. According to this configuration, a feedback loop is formed so that the output voltage of the DC / DC converter approaches a target value, so that the response speed required of the DC / DC converter can be reduced.

[0041] The array type light emitting device may be configured to acquire second data related to voltage drops of a plurality of light emitting elements included in a plurality of pixel circuits and transmit the data to an external device. The power supply control circuit may set a target value based on the second data in addition to the light distribution pattern. By monitoring the voltage drops of the light emitting elements during actual operation, the minimum operating voltage of the array type light emitting device can be accurately estimated. Then, the voltage drops of the light emitting elements can be reflected in the feedback control of the power supply circuit in real time, thereby reducing power consumption.

[0042] 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 spatially arranged in a matrix, a power supply circuit for supplying power to the array-type light-emitting device, and a connection means including a power cable for 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 supply control circuit that obtains a voltage drop in the power cable, sets a target value according to the voltage drop in the power cable, and controls the DC / DC converter so that the output voltage of the DC / DC converter approaches the target value.

[0043] By monitoring the voltage drop in the power cable and dynamically and adaptively changing the target value of the output voltage in response to the voltage drop, it is possible to prevent the power supply voltage supplied to the array-type light-emitting device from falling below the minimum operating voltage, and also to reduce unnecessary power consumption.

[0044] 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. The power supply control circuit may obtain a voltage drop in the power supply line and set a target value according to the voltage drop in the power supply line.

[0045] 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 may obtain voltage drops in the power line and the ground line, and set a target value according to the voltage drops in the power line and the ground line.

[0046] In one embodiment, the power supply circuit may further include a current sensor that generates a current detection signal according to the output current of the DC / DC converter. The power supply control circuit may set a target value according to the current detection signal.

[0047] 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 through a detection line independent of the power cable. The power supply control circuit may obtain a voltage drop of the connection means based on a difference between the output voltage of the DC / DC converter and the detection voltage of the detection terminal.

[0048] In one embodiment, the power supply control circuit may include a feedback circuit that generates a feedback voltage based on the output voltage of the DC / DC converter and a compensation voltage corresponding to the voltage drop of the connection means, and a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter so that the feedback voltage approaches a predetermined reference voltage.

[0049] In one embodiment, the power supply control circuit may include a voltage setting circuit that generates a reference signal corresponding to the voltage drop of the connection means, a feedback pin that receives a feedback voltage corresponding to the output voltage, and a converter controller that has a reference voltage setting pin that receives the reference signal, and controls the DC / DC converter so that the feedback voltage approaches a reference voltage based on the reference signal.

[0050] 3. A lighting system according to an embodiment includes a variable light distribution light source including an array-type light-emitting device, and a power supply circuit that supplies power to the array-type light-emitting device. The array-type light-emitting device includes a plurality of pixel circuits. The pixel circuits are electrically connected in parallel, spatially arranged in a matrix, and each includes a light-emitting element and a current source that are connected in series. The array-type light-emitting device is configured to acquire data related to a voltage drop of a plurality of light-emitting elements included in the plurality of pixel circuits, and transmit the data to the outside. 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 supply control circuit that controls the DC / DC converter so that a controlled voltage approaches a target value according to the data.

[0051] By monitoring the voltage drop of the light-emitting elements during actual operation, it is possible to accurately estimate the minimum operating voltage of the array-type light-emitting device. Furthermore, by reflecting the voltage drop of the light-emitting elements in real time in the feedback control of the power supply circuit, it is possible to reduce power consumption.

[0052] In one embodiment, the target value may be based on a maximum voltage drop across a number of light emitting elements.

[0053] In one embodiment, the power supply control circuit may include a voltage setting circuit that generates a correction voltage according to 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 a DC / DC converter so that the feedback voltage approaches a predetermined reference voltage. When a converter controller whose internal reference voltage cannot be set externally is used, the target value of the controlled voltage can be set by shifting the feedback voltage according to the correction voltage.

[0054] In one embodiment, the voltage setting circuit may include a microcontroller that generates a digital setpoint according to data, and a D / A converter that converts the setpoint into an analog correction voltage, allowing the target value of the controlled voltage to be software controlled.

[0055] In one embodiment, the power supply control circuit may include a converter controller having a voltage setting circuit that generates a setting signal according to data, a feedback pin that receives a feedback voltage according to a controlled voltage, and a reference voltage setting pin that receives the setting signal, and that controls the DC / DC converter so that the feedback voltage approaches a reference voltage based on the reference signal. When a converter controller capable of controlling an internal reference voltage from outside is employed, the target value of the controlled voltage can be set by directly controlling the internal reference voltage of the converter controller according to data.

[0056] In one embodiment, the voltage setting circuit may include a microcontroller that generates a digital set point in response to the data. The reference voltage may be dependent on the set point, allowing software control of the target value of the controlled voltage.

[0057] 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 independent of the power cable. The controlled voltage may be a detection voltage generated at the detection terminal. With this configuration, a feedback loop is formed so that an appropriate power supply voltage is supplied to the power supply terminal of the array type light-emitting device. Therefore, unnecessary power consumption can be reduced.

[0058] In one embodiment, the controlled voltage may be the output voltage of the DC / DC converter. According to this configuration, a feedback loop is formed so that the output voltage of the DC / DC converter approaches a target value, so that the response speed required of the DC / DC converter can be reduced.

[0059] In one embodiment, the lighting system may further include a control unit connected to the interface circuit of the array-type light-emitting device and controlling the on / off of the plurality of pixel circuits of the array-type light-emitting device. The power supply control circuit may receive data via the control unit.

[0060] In one embodiment, the microcontroller may obtain an error between the controlled voltage and the target value based on the data, and if the converter controller cannot detect a situation in which the controlled voltage deviates from the target value, the microcontroller can detect an abnormal condition by monitoring the error between the controlled voltage and the target value.

[0061] In one embodiment, the microcontroller may determine that an abnormality has occurred when the error between the controlled voltage and the target value exceeds a predetermined threshold.

[0062] In one embodiment, when the microcontroller determines that an abnormality has occurred, the set value may be fixed to a predetermined value. By setting the predetermined value high, a high voltage is forcibly supplied to the array-type light-emitting device in an abnormal state, so that the light can be maintained.

[0063] In one embodiment, the microcontroller may store a history of data. If a log is stored in the electronic device, the electronic device vendor or the manufacturer of the equipment in which the electronic device is mounted can use the log for failure analysis and new product development. In particular, since the voltage drop of the light-emitting element is an important parameter that serves as an index of efficiency and temperature, it is useful to store the voltage drop as a log.

[0064] In one embodiment, the lighting system may further include a temperature sensor. The microcontroller may store information regarding the temperature acquired by the temperature sensor.

[0065] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions will be omitted as appropriate. In addition, the embodiments are illustrative and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0066] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection state between them or that do not impair the function or effect achieved by their combination.

[0067] Similarly, "a state in which component C is provided between components A and B" includes not only the case in which components A and C, or components B and C, are directly connected to each other, but also the case in which they are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the functions or effects achieved by their combination.

[0068] In this specification, symbols attached to electrical signals such as voltage signals and current signals, or circuit elements such as resistors and capacitors, represent the respective voltage values, current values, resistance values, or capacitance values ​​as necessary.

[0069] (Embodiment 1) 4 is a block diagram of the lighting system 100 according to the embodiment 1. The lighting system 100 is an ADB lamp system, and includes a battery 102, a host controller 104, and a headlamp 200.

[0070] The upper controller 104 generates a light distribution command for the headlamp 200. The light distribution command may include a lighting command and additional information. The lighting command may include a signal instructing high beam or low beam to be on or off. A basic light distribution to be formed by the headlamp 200 is determined in response to the lighting command. The additional information may include data on an area where the high beam should not be irradiated (shading area), and information such as the vehicle speed and steering angle. The basic light distribution is corrected in response to the additional information, and a final light distribution is determined. The upper controller 104 may be configured as an ECU on the vehicle side, or as an ECU on the lamp side built into the headlamp 200.

[0071] The headlamp 200 is an ADB lamp that includes a variable light distribution light source 210, a power supply circuit 220, and a control unit 260.

[0072] The variable light distribution light source 210 includes a plurality of pixels arranged in an array, and each pixel can be individually controlled to be turned on or off. In the headlamp 200, the plurality of pixels are controlled to be turned on or off so as to obtain a desired light distribution.

[0073] More specifically, the variable light distribution 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 plurality of pixel circuits PIX1 to PIXn.

[0074] A pixel circuit PIXj (1≦j≦n) includes a light emitting element 213_j and a current source 214_j that are provided in series between a power supply terminal VDD and a ground terminal (ground line) GND. The 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 spatially arranged in an array (matrix).

[0075] The 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 turned on.

[0076] The interface circuit 216 controls the on / off of the current sources 214_1 to 214_n in response to a 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 that instructs the on / off of all the pixels.

[0077] The power supply circuit 220 supplies power to the variable light distribution light source 210. The power supply circuit 220 includes a constant voltage output converter, and supplies a stabilized power supply voltage V DD Supply voltage V DD V F +V SAT It is determined based on the voltage, typically around 4 to 5 V. F is the forward voltage of the light emitting element 213, V SAT is the minimum operating voltage of the current source 214. Therefore, the power supply circuit 220 is connected to a battery voltage V BAT It can be configured with a step-down converter (Buck converter) that steps down the

[0078] The control unit 260 receives a light distribution command S1 from the upper controller 104, generates a control signal S2 according to the light distribution command S1, and transmits 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 controls the PWM of the 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 (for example, 100 to 400 Hz), and therefore the PWM period is several milliseconds to several tens of milliseconds (ms).

[0079] Next, a description will be given of the configuration of the power supply circuit 220. The power supply circuit 220 includes output terminals AP / AN, a ground terminal GND, a DC / DC converter 224, and a power supply control circuit 225.

[0080] 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 a power cable 204. The power supply cable 204 includes a power supply line LVDD and a ground line LGND. A 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 the output terminal AP and the power supply line LVDD, and a 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 the output terminal AN and the ground line LGND. A voltage V from the battery is input to the input of the DC / DC converter 224. BAT is supplied.

[0081] The power supply control circuit 225 controls the controlled voltage V CNT The target value of V CNT(REF) and set the controlled voltage V CNT is the target value V CNT(REF) For example, the power supply control circuit 225 receives data S4 from the control unit 260, the data S4 including information regarding the light distribution.

[0082] As will be described later in detail, the controlled voltage V CNT is the power supply voltage V of the array type light emitting device 212 DDAlternatively, the output voltage V OUT may be also possible.

[0083] The above is the configuration of the lighting system 100. The present disclosure extends to various devices and methods understood as the block diagram or circuit diagram of Fig. 4 or derived from the above description, and is not limited to a specific configuration. Below, more specific configuration examples and examples will be described not to narrow the scope of the present invention, but to aid in understanding the essence and operation of the invention and to clarify them.

[0084] Next, the operation of the lighting system 100 will be described with reference to some control examples.

[0085] (Control example 1) 5 is a diagram showing an operation according to a first control example of the lighting system 100 of FIG. CNT is the power supply voltage V of the array type light emitting device 212. DD The power supply control circuit 225 controls the power supply voltage V DD The target value of V DD(REF) is controlled according to the light distribution pattern.

[0086] At time t1, the light distribution pattern is changed from the first pattern PTN1 to the second pattern PTN2, and the current I OUT2 The current I of the first pattern PTN1 OUT For example, the first pattern PTN1 is a light distribution in town mode, and the low beam area is illuminated. The second pattern PTN2 is a light distribution in active mode, and the high beam area is also illuminated, so the number of lit pixels is relatively large and the output current I OUT is also relatively large.

[0087] In the steady state, the power supply voltage V DD The target value of V DD(REF) is the minimum operating voltage V DD(MIN) is set to the same extent.

[0088] Prior to changing the light distribution pattern PTN, in other words, the power supply control circuit 225 controls the current I OUT At time t0 prior to the timing of the increase in the power supply voltage V DD The target value of V DD(REF) Increase the power supply voltage V by ΔV. DD is the target value V DD(REF) The increase in the target value ΔV is proportional to the change in the power supply voltage V DD The target value V DD(REF) The timing t0 at which to increase can be provided by the control unit 260.

[0089] When the light distribution pattern PTN is switched at time t1, the current I OUT As a result, the power supply voltage V DD decreases, and the target value V DD(REF) The error with the target value V DD(REF) Return to.

[0090] At time t2, the power supply control circuit 225 sets the target value V DD(REF) Return to the original voltage level. Target value V DD(REF) The power supply voltage V DD drops to its original voltage level.

[0091] In the control example 1, the output voltage V OUT V OUT =V DD +V DROP V DROP is the voltage drop in the power supply line LVDD and connector, and V DROP =I OUT It is expressed as ×R.

[0092] The above is the operation according to the control example 1. According to this control example, before changing the light distribution pattern, the power supply voltage V DD The target voltage V DD(REF) By increasing the supply voltage V DD The minimum operating voltage V DD(MIN)It can be maintained at a higher level and flicker-free.

[0093] (Control example 2) 6 is a diagram showing an operation according to a second control example of the lighting system 100 of FIG. CNT is the output voltage V of the DC / DC converter 224. OUT and the power supply control circuit 225 controls the output voltage V OUT The target value of V OUT(REF) In the control example 2, the response speed of the power supply control circuit 225 is sufficiently fast, and the output current I OUT Even if a sudden change in the output voltage V OUT can be maintained constant.

[0094] The power supply control circuit 225 controls the amount of current I OUT# Based on this, the target value V OUT(REF)# The target value for each light distribution pattern is expressed by the following formula (A). V OUT(REF)# =V DD(MIN) +R×I OUT# …(A)

[0095] The above is the operation according to the control example 2. According to this control example, the output voltage V OUT The controlled voltage V CNT In this configuration, the output current I OUT Depending on the target value V OUT(REF) By setting the power supply voltage V DD The minimum operating voltage V DD(MIN) This allows the device to be kept close to the ground, reducing unnecessary power consumption.

[0096] (Control example 3) In control example 3, similar to control example 2, the controlled voltage V CNT is the output voltage V of the DC / DC converter 224. OUT In the control example 3, similarly to the control example 2, the target value V OUT(REF)In addition, in the control example 3, similarly to the control example 1, when a change in the light distribution pattern occurs accompanied by a steep current fluctuation, the target value V OUT(REF) is increased by a predetermined voltage step ΔV.

[0097] According to the control example 3, when the response speed of the power supply control circuit 225 is slow, it is possible to prevent flicker from occurring.

[0098] (Control example 4) In control example 4, like control example 2, the controlled voltage V CNT is the output voltage V of the DC / DC converter 224. OUT In control example 4, the target value V OUT(REF) In the same manner as in control example 1, when a change in the light distribution pattern occurs accompanied by a steep current fluctuation, the target value V OUT(REF) is increased by a predetermined voltage step ΔV.

[0099] According to the control example 4, when the response speed of the power supply control circuit 225 is slow, it is possible to prevent flicker from occurring.

[0100] (Control based on device information) Returning to Fig. 4, the lighting system 100 may further include the following features.

[0101] The interface circuit 216 of the array type light emitting device 212 detects the voltage drop (i.e., forward voltage) V F1 ~V Fn Monitor the forward voltage V F1 ~V Fn In this embodiment, the data S3A is transmitted to the power supply circuit 220 via the control unit 260 as data S3B.

[0102] The power supply control circuit 225 converts the data S3B into the controlled voltage V CNT The target value of V CNT(REF) The controlled voltage V CNTThe target value of V CNT(REF) is the forward voltage V of the light emitting element 213 of all channels F1 ~V Fn Maximum value of V F(MAX) For example, the data S3B received by the power supply control circuit 225 may correspond to the forward voltages V F1 ~V Fn In this case, the power supply control circuit 225 may include a forward voltage V F1 ~V Fn Maximum value of V F(MAX) Obtain the maximum value V F(MAX) Based on this, the target value V CNT(REF) Alternatively, the control unit 260 may generate a forward voltage V F1 ~V Fn Maximum value of V F(MAX) Obtain the maximum value V F(MAX) The data S3B including the above may be transmitted to the power supply control circuit 225.

[0103] Figure 7(a) and (b) show the forward voltage V F 7A and 7B are diagrams for explaining the control of the target value based on the forward voltage V Fi is the maximum value V F(MAX) The controlled voltage V CNT The power supply voltage V DD The target value of V DD(REF) teeth, V DD(REF) =V D +V Fi(MAX) +α V D is the voltage drop of the current source 214, and α is a margin.

[0104] In FIG. 7B, the forward voltage V of the j-th pixel PIXj of the array-type light-emitting device 212 Fj is the maximum value V F(MAX) The controlled voltage V CNT The power supply voltage V DD The target value of V DD(REF) teeth, V DD(REF) =V D +V Fj +α It is determined based on.

[0105] As shown in Figure 7(a) and (b), the forward voltage V F Using this, the target value V DD(REF) By determining the value V DD(SPEC) than the power supply voltage V DD This allows the power consumption of the array type light emitting device 212 to be reduced.

[0106] Fig. 8 is a diagram showing the operation of the lighting system 100. Fig. 8 shows how one lighting system 100 operates in different temperature environments. The forward voltage V F has temperature dependency, and decreases as the temperature increases. According to this embodiment, the controlled voltage V DD The target value of V DD(REF) Since the power consumption can be reduced, the power consumption can be reduced.

[0107] The above is the control based on the device information. According to this lighting system 100, the voltage drop V F The power consumption can be reduced by reflecting the information on the forward voltage V of the light emitting element 213 in real time to the feedback control of the power supply circuit 220. F By monitoring the actual minimum operating voltage V DD(MIN) The minimum operating voltage V DD(MIN) reflects individual variations and temperature fluctuations of the array-type light-emitting device 212, and is a value V DD(SPEC) Therefore, the exact minimum operating voltage V DD(MIN) Based on this, the operating conditions of the power supply circuit 220 are dynamically determined, so that the power supply voltage V DD can be lowered, and power consumption can be reduced.

[0108] Next, a specific configuration example of the headlamp 200 will be described. F The description of the control of the target value based on the data S3 regarding is omitted.

[0109] Example 1.1 9 is a block diagram of a headlamp 200A according to Example 1.1. The headlamp 200A includes a variable light distribution light source 210, a power supply circuit 220A, and a control unit 260.

[0110] The power supply circuit 220A includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225A. The power supply control circuit 225A includes a feedback circuit 226A, a converter controller 228, and a voltage setting circuit 230.

[0111] The converter controller 228 can use a commercially available DC / DC converter control IC (Integrated Circuit). The converter controller 228 controls the feedback voltage V FB is the internally generated reference voltage V REF A pulse signal is generated in which at least one of the pulse width, frequency, and duty cycle is adjusted so as to approach the above-mentioned value, and the DC / DC converter 224 is feedback-controlled in response to the pulse signal.

[0112] The voltage setting circuit 230 receives data S4 generated by the array type light emitting device 212. Based on the received data S4, the voltage setting circuit 230 sets the correction voltage V CMP The feedback circuit 226A generates the output voltage V OUT The controlled voltage V CNT and the correction voltage V CMP Based on this, the feedback voltage V FB and supplies it to the feedback pin FB of the converter controller 228. FBis the controlled voltage V CNT and the correction voltage V CMP It is a signal that changes depending on each and is expressed by equation (1). V FB =K1 V CNT +K2·V CMP …(1) where K1 is a constant >0 and K2 is a non-zero constant. Here, K2<0. The converter controller 228 calculates the feedback signal V FB is the target value V REF The DC / DC converter 224 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0113] When the system is in a stable steady state, K1·V CNT +K2·V CMP =V REF Therefore, in the steady state, the controlled voltage V CNT is the target value V CNT(REF) is stabilized to. V CNT(REF) =(V REF -K2·V CMP ) / K1…(2)

[0114] In this Example 1.1, the controlled voltage V CNT is the voltage V of the power supply terminal VDD of the array type light emitting device 212 DD It is.

[0115] The detection terminal SNS of the power supply circuit 220A is connected to the power supply terminal VDD of the array type light emitting device 212 via a detection line (direct line) LSNS that is independent of the power cable 204 (power supply line LVDD). The input impedance of the feedback circuit 226A is sufficiently high, and no current flows through the detection line LSNS. Therefore, the detection voltage V SNS is the voltage V of the power supply terminal VDD of the array type light emitting device 212 DD The feedback circuit 226A receives the detection voltage V SNS is the controlled voltage V CNT Therefore, the power supply voltage VDD The target value of V DD(REF) is expressed by equation (3). V DD(REF) =(V REF -K2·V CMP ) / K1…(3) In other words, the correction voltage V CMP By changing the power supply voltage V DD The target value of V DD(REF) can be varied.

[0116] The above is the configuration of the headlamp 200A. Next, the operation will be described. Fig. 10 is an operational waveform diagram of the headlamp 200A in Fig. 9. This operation corresponds to the above-mentioned control example 1.

[0117] In the steady state, the correction voltage V CMP is a steady value (0 V in this example). At time t1, an instruction is given to switch the light distribution pattern from PTN1 to PTN2. Prior to this, at time t0, the voltage setting circuit 230 sets the correction voltage V CMP As a result, the target value V DD(REF) Then, the voltage setting circuit 230 shifts the correction voltage V CMP Return to the steady state value.

[0118] At time t2, the current I OUT In this case, the voltage setting circuit 230 changes the light distribution pattern with a decrease in the correction voltage V CMP should be maintained at a steady value.

[0119] The above is the operation of the headlamp 200A. According to the headlamp 200A, the correction voltage V CMP By changing the voltage V DD The target value of V DD(REF) It becomes possible to dynamically control the

[0120] Next, configuration examples of the voltage setting circuit 230 and the feedback circuit 226A will be described.

[0121] 11 is a circuit diagram showing an example of the configuration of the feedback circuit 226A. The feedback circuit 226A is a subtraction circuit having an operational amplifier, and includes resistors R31 to R34 and an operational amplifier OA3. The input / output characteristics of the feedback circuit 226A are expressed by equation (5). V FB =(R31+R32) / R31×{R34 / (R33+R34)×V CNT -R32 / (R31+R32)×V CMP …(5)

[0122] Comparing equations (1) and (5), K1=(R31+R32) / R31×R34 / (R33+R34) K2=-(R31+R32) / R31×R32 / (R31+R32) get.

[0123] The feedback circuit 226A may be configured as an adder circuit using an operational amplifier. In this case, K1>0, K2>0. The correction voltage V CMP When is positive, the correction voltage V CMP Depending on the voltage V CNT The target value of can be shifted to the lower potential side.

[0124] 12 is a circuit diagram showing a configuration example 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 controls the forward voltage V F According to the data S4 on the correction voltage V CMP Specify the digital setting value D CMP Using the microcontroller 240, the correction voltage V CMP It is now possible to control the above using software.

[0125] The D / A converter 234 converts the set value D CMP , the analog correction voltage V CMPConvert to the correction voltage V CMP is supplied to the feedback circuit 226A via a buffer 236. If the output impedance of the D / A converter 234 is sufficiently low, the buffer 236 can be omitted. If a microcontroller 240 with a built-in D / A converter is used, the D / A converter 234 will be present inside the microcontroller 240.

[0126] Example 1.2 13 is a block diagram of a headlamp 200B according to Example 1.2. The configuration of the headlamp 200B will be described, focusing on the differences from Example 1.1. The headlamp 200B includes a variable light distribution light source 210, a power supply circuit 220B, and a control unit 260. In Example 1.2, the configuration of the power supply circuit 220B is different from that of the power supply circuit 220A in Example 1.1.

[0127] The power supply circuit 220B includes an output terminal OUT, a DC / DC converter 224, and a power supply control circuit 225B. The power supply control circuit 225B includes a feedback circuit 226B, a converter controller 228, and a voltage setting circuit 230.

[0128] In Example 1.2, the output voltage V OUT is the controlled voltage V CNT The feedback circuit 226B has an output voltage V OUT is the controlled voltage V CNT Therefore, the output voltage V OUT The target value of V OUT(REF) is expressed by the following equation (6): The feedback circuit 226B may be a subtraction circuit, similar to the feedback circuit 226A in the embodiment 1.1. V OUT(REF) =(V REF -K2·V CMP ) / K1…(6)

[0129] Next, the operation of the headlamp 200B will be described. In the embodiment 1.2, any one of the above-mentioned control examples 2 to 4 can be adopted.

[0130] 14 is an operational waveform diagram of the headlamp 200B employing the control example 2. In the periods T1 to T3, the light distribution patterns PTN1 to PTN3 are set, and the output current I OUT I OUT1 ,I OUT2 ,I OUT3 It changes as follows.

[0131] In each light distribution pattern PTN1 to PTN3, the correction voltage V CMP is the output current I OUT According to this control, the output current I OUT Depending on the target value V OUT(REF) By changing the power supply voltage V DD can be kept constant.

[0132] FIG. 15 is an operational waveform diagram of the headlamp 200B employing the control example 4. CMP is the output current I OUT The former includes a component substantially proportional to the correction voltage V CMP Corresponds to.

[0133] According to control example 4, when a change in the light distribution pattern occurs accompanied by an increase in current, the output voltage V OUT The target value of V OUT(REF) can be increased.

[0134] The above is the operation of the headlamp 200B. According to the headlamp 200B, the correction voltage V CMP In response to this, the output voltage V OUT A target value can be set.

[0135] (Example 1.3) 16 is a block diagram of a headlamp 200C according to Example 1.3. The configuration of the headlamp 200C will be described, focusing on the differences from Example 1.2.

[0136] The headlamp 200C includes a variable light distribution light source 210, a power supply circuit 220C, and a control unit 260. In the embodiment 1.3, the configuration of the power supply circuit 220C is different from that of the power supply circuit 220B in the embodiment 1.2.

[0137] The configuration of the power supply circuit 220C will be described below. The power supply circuit 220C includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225C.

[0138] The power supply control circuit 225C includes a feedback circuit 226C, a converter controller 228, and a voltage setting circuit 230.

[0139] The feedback circuit 226C includes a controlled voltage V CNT As the output voltage V OUT The feedback circuit 226C also receives the power supply voltage V DD Furthermore, the feedback circuit 226C receives the correction voltage V generated by the voltage setting circuit 230. CMP is entered.

[0140] The correction voltage V generated by the voltage setting circuit 230 CMP When a change in the light distribution pattern occurs accompanied by an increase in current, the voltage setting circuit 230 sets the correction voltage V CMP Increase.

[0141] The feedback circuit 226C outputs three voltages V OUT ,V SNS ,V CMP Based on this, the feedback voltage V FB The feedback circuit 226C generates V OUT and V SNS Based on the difference between the voltage drop VDROP =V OUT -V SNS Detect.

[0142] The feedback voltage V generated by the feedback circuit 226C FB is expressed by equation (8). V FB =K1 V OUT +K2·V CMP +K3·V DROP …(8)

[0143] The above is the configuration of the headlamp 200C. In this headlamp 200C, the output voltage V OUT The target value of V OUT(REF) is expressed by equation (9). V OUT(REF) =(V REF -K2·V CMP -K3·V DROP ) / K1…(9) If K2<0,K3<0, V OUT(REF) =(V REF +|K2|·V CMP +|K3|·V DROP ) / K1…(9') When |K3|=K1 holds, V OUT(REF) =(V REF +|K2|·V CMP ) / K1+V DROP …(9'')

[0144] According to Example 1.3, the actually detected voltage drop V DROP Based on this, the output voltage V OUT The target value of V OUT(REF) This allows the power consumption to be reduced by optimizing the correction voltage V CMP By doing this, it is possible to recover the voltage drop caused by the response delay. In addition, by appropriately determining the gain K3, it is possible to correct the voltage drop of the ground line LGND.

[0145] 17 is a functional block diagram of the feedback circuit 226C. The feedback circuit 226C may include three subtraction circuits SUB1 to SUB3. The subtraction circuit SUB1 subtracts the output voltage V OUT to detection voltage V SNS Subtract the voltage drop V DROP The subtraction circuit SUB2 calculates the output voltage V OUT Voltage drop from V DROP The subtraction circuit SUB3 subtracts the output voltage V OUT -V DROP Then, the correction voltage V CMP The order of subtraction may be reversed.

[0146] Example 1.4 18 is a circuit diagram of a headlamp 200D according to Example 1.4. The headlamp 200D includes a variable light distribution light source 210, a power supply circuit 220D, and a control unit 260.

[0147] The configuration of the power supply circuit 220D will be described below. The power supply circuit 220D includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225D.

[0148] The power supply 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, and receives a reference signal S REF Depending on the REF The converter controller 228D is capable of setting the reference signal S REF is received as a digital signal, and the internal voltage source generates a reference voltage V REF Alternatively, the converter controller 228D may generate an analog reference signal S REF and directly feeds it to the internal reference voltage V REF The converter controller 228D may utilize the voltage V FB is the reference signal S REFReference voltage V based on REF The DC / DC converter 224 is feedback-controlled so as to approach

[0149] The voltage setting circuit 230D sets the reference signal S REF and supplies it to the reference voltage setting pin REF of the converter controller 228D. REF When V is an analog voltage, the voltage setting circuit 230D can be configured similarly to that shown in FIG. 12, and the correction voltage V CMP Let S be the reference signal. REF The reference signal S REF If the set value D is a digital signal, the voltage setting circuit 230D can be configured only by the microcontroller 240 of FIG. CMP , the reference signal S REF This can be read as follows.

[0150] The feedback circuit 226D is a control target voltage V CNT Feedback voltage V according to FB and supplies it to the feedback pin FB of the converter controller 228D.

[0151] As in Example 1.2, the controlled voltage V CNT is the output voltage V OUT In this case, the feedback voltage V FB is expressed by equation (10). V FB =K1 V OUT …(10)

[0152] As in the embodiment 1.1, the power supply circuit 220D and the variable light distribution light source 210D are connected by a detection line LSNS, and the detection voltage V SNS (=V DD ) to be controlled by the voltage V CNT In this case, the feedback voltage V FB is expressed by equation (11). V FB =K1 V SNS =K1 V DD …(11)

[0153] As in Example 1.3, the output voltage V OUT The controlled voltage V CNT and the voltage drop V on the power supply line LVDD DROP The voltage after the correction is called the feedback voltage V FB In this case, the feedback voltage V FB is expressed by equation (12). V FB =K1 V OUT +K3·V DROP …(12)

[0154] As explained in Example 1.3, the voltage drop V DROP The power supply circuit 220D and the variable light distribution light source 210D are connected by a detection line LSNS, and V OUT and V SNS It can be obtained by calculating the difference between

[0155] According to Example 1.4, the same effects as those of Examples 1.1 to 1.3 can be obtained.

[0156] Next, a modification related to the first embodiment will be described.

[0157] (Variation 1.1) FIG. 19 is a diagram showing a headlamp 200 according to Modification 1.1. In the above description, the variable light distribution light source 210 includes one array-type light-emitting device 212. However, the variable light distribution light source 210 may include a plurality of array-type light-emitting devices 212. In this case, the power supply circuit 220 may be unitized (referred to as a power supply unit 222) and a plurality of power supply units 222 may be provided corresponding to the plurality of array-type light-emitting devices 212. An output terminal of each power supply unit 222 is connected to a power supply terminal of the corresponding array-type light-emitting device 212 via an individual power supply cable LVDD. Furthermore, a detection line LSNS may be provided for each pair of the power supply unit 222 and the array-type light-emitting device 212, as necessary. In this modification, the microcontroller 240 may be shared by the plurality of power supply units.

[0158] In this modification 1.1, the variable light distribution light source 210 is divided into a plurality of array-type light-emitting devices 212 with independent power supply terminals. 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 a power cable. This allows the current flowing through the variable light distribution light source 210 to be distributed to a plurality of DC / DC converters, reducing the effect of voltage drop in each DC / DC converter and improving load responsiveness. In addition, there are more options for DC / DC converter components, power cables, and connectors, allowing for greater freedom in design.

[0159] (Variation 1.2) 20 is a diagram showing a headlamp 200 according to Modification 1.2. In the array type light emitting device 212, a plurality of internal light emitting pixels are divided into a plurality of segments SEG1 to SEGn, and a plurality of power supply terminals VDD may be provided corresponding to the plurality of segments SEG1 to SEGn. In the power supply circuit 220, a plurality of power supply units 222 are provided corresponding to the plurality of power supply terminals VDD. An output terminal OUT of each power supply unit 222 is connected to a corresponding power supply terminal VDD of the array type light emitting device 212 via an individual power supply cable LVDD. In addition, a detection line LSNS may be provided for each power supply unit 222 as necessary.

[0160] In this modification 1.2 as well, the current flowing through the variable light distribution light source 210 can be distributed to a plurality of DC / DC converters, and the same effect as in modification 1.1 can be obtained.

[0161] (Variation 1.3) The power supply unit 222 may be configured with a phase-shift type converter. By adopting a phase-shift type converter, the output voltage V OUTi and output current I OUTi In addition, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I OUTiSince the load fluctuates rapidly in response to the lighting rates of multiple pixel circuits, the use of a phase-shift converter can improve the response to load fluctuations.

[0162] (Variation 1.4) Although the case has been described where power supply circuit 220 and control unit 260 are built into headlamp 200, one or both of them may be provided on the outside of the body of headlamp 200. Since variable light distribution light source 210 is a heat generating body, it is advantageous from the viewpoint of thermal design to place control unit 260, which avoids heat, inside the vehicle cabin away from variable light distribution light source 210.

[0163] (Variation 1.5) The power supply control circuit 225 may receive information regarding the light distribution pattern directly from the upper controller 104 without going through the control unit 260.

[0164] (Variation 1.6) The power supply control circuit 225 controls the forward voltage V F1 ~V Fn The power supply control circuit 225 may determine the target value based on the maximum value of the forward voltage V F The target value may be determined based on the maximum value of

[0165] (Variation 1.7) An array type light emitting device is a device that controls the forward voltage V F The maximum value of V F(MAX) It may be measured in advance and stored in the internal non-volatile memory. F(MAX) may be the maximum value for all pixels and the entire temperature range. Alternatively, the forward voltage V F(MAX) and transmit data including a maximum value according to the current temperature.

[0166] (Embodiment 2) 21 is a block diagram of a lighting system 100 according to embodiment 2. The lighting system 100 is an ADB lamp system, and includes a battery 102, a host controller 104, and a headlamp 200.

[0167] The upper controller 104 generates a light distribution command for the headlamp 200. The light distribution command may include a lighting command and additional information. The lighting command may include a signal instructing high beam or low beam to be on or off. A basic light distribution to be formed by the headlamp 200 is determined according to the lighting command. The additional information may include data on an area where the high beam should not be irradiated (shading area), and information such as the vehicle speed and steering angle. The basic light distribution is corrected according to the additional information, and a final light distribution is determined. The upper controller 104 may be configured as an ECU (Electronic Control Unit) on the vehicle side, or may be configured as an ECU on the lamp side built into the headlamp 200.

[0168] The headlamp 200 is an ADB lamp including a variable light distribution light source 210, a power supply circuit 220, a connection means 202, and a control unit 260.

[0169] The variable light distribution light source 210 includes a plurality of pixels arranged in an array, and each pixel can be individually controlled to be turned on or off. In the headlamp 200, the plurality of pixels are controlled to be turned on or off so as to obtain a desired light distribution.

[0170] More specifically, the variable light distribution 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 plurality of pixel circuits PIX1 to PIXn.

[0171] A pixel circuit PIXj (1≦j≦n) includes a light emitting element 213_j and a current source 214_j that are provided in series between a power supply terminal VDD and a ground terminal (ground line) GND. The 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 spatially arranged in an array (matrix).

[0172] The 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 turned on.

[0173] The interface circuit 216 controls the on / off of the current sources 214_1 to 214_n in response to a 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 that instructs the on / off of all the pixels.

[0174] The power supply circuit 220 supplies power to the variable light distribution light source 210. The power supply circuit 220 includes a constant voltage output converter, and supplies a stabilized power supply voltage V DD Supply voltage V DD V F +V SAT It is determined based on the voltage, typically around 4 to 5 V. F is the forward voltage of the light emitting element 213, V SAT is the minimum operating voltage of the current source 214. Therefore, the power supply circuit 220 is connected to a battery voltage V BAT It can be configured with a step-down converter (Buck converter) that steps down the

[0175] The control unit 260 receives a light distribution command S1 from the upper controller 104, generates a control signal S2 according to the light distribution command S1, and transmits 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 controls the PWM of the 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 (for example, 100 to 400 Hz), and therefore the PWM period is several milliseconds to several tens of milliseconds (ms).

[0176] The power supply circuit 220 and the array type light emitting device 212 are connected via a connection means 202 including a power cable 204. In addition to the power cable 204, the connection means 202 may include connectors (couplers) 206A, 206B, and the like.

[0177] Next, a description will be given of the configuration of the power supply circuit 220. The power supply circuit 220 includes a DC / DC converter 224 and a power supply control circuit 225.

[0178] The power cable 204 includes a power line LVDD and a ground line LGND. A positive output terminal OUTP of the DC / DC converter 224 is connected to a power terminal VDD of the array type light-emitting device 212 via the power line LVDD. A negative output terminal OUTN of the DC / DC converter 224 is connected to a ground terminal GND of the array type light-emitting device 212 via the ground line LGND.

[0179] The impedance of the power supply line LVDD and the ground line LGND is R VDD ,R GND Let us assume that.

[0180] The input of the DC / DC converter 224 is the voltage V BAT is supplied, and the output is connected to the array type light emitting device 212 via the connection means 202. The power supply control circuit 225 controls the voltage drop V DROP Get the.

[0181] The voltage drop V of the connection means 202 DROP may include the voltage drop in the power cable 204 and the voltage drop in the connector 206. More specifically, the voltage drop V DROP may include a voltage drop V1 of the power supply line LVDD, a voltage drop V2 of the ground line LGND, a voltage drop V3 of the connector 206A, and a voltage drop V4 of the connector 206B. The power supply control circuit 225 calculates the sum of these voltage drops V1 to V4 as the voltage drop V DROP It may be obtained as. V DROP =V1+V2+V3+V4

[0182] Alternatively, if the voltage drop at the connector 206 is relatively small compared to that of the power cable 204, only the voltage drops V1 and V2 of the power cable 204 are considered as the voltage drop V DROP It may be obtained as. V DROP =V1+V2

[0183] Alternatively, when the body ground is used as the ground line LGND, the impedance is sufficiently low. In that case, only the voltage drop V1 of the power line LVDD of the power cable 204 is reduced by the voltage drop V DROP It may be obtained as.

[0184] The power supply control circuit 225 detects the obtained voltage drop V DROP Depending on the target value V OUT(REF) Set. V OUT(REF) =V DD(MIN) +V DROP The power supply control circuit 225 controls the output voltage V OUT is the target value V OUT(REF) The DC / DC converter 224 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0185] The above is the configuration of the lighting system 100. Next, the operation of the lighting system 100 will be described.

[0186] FIG. 22 is a diagram illustrating the operation of the lighting system 100 of FIG. 21. OUT The output current I OUT Voltage drop V proportional to DROP occurs. V DROP =R×I OUT R is the impedance of the connection means 202.

[0187] The power supply control circuit 225 controls the voltage drop V DROP and obtain the voltage drop V DROP Target value V according to OUT(REF) Then, the power supply control circuit 225 sets the output voltage V OUT The target value V expressed by the above formula OUT(REF) The voltage stabilizes to .

[0188] The input voltage V applied between the power supply terminal VDD and the ground terminal GND of the array type light emitting device 212 B is the voltage V between the positive and negative outputs OUTP and OUTN of the DC / DC converter 224 A , i.e., the output voltage V OUT Therefore, the voltage drop V DROP In this embodiment, the power supply circuit 220 reduces the voltage drop V DROP The output voltage V OUT Therefore, the input voltage V of the array type light emitting device 212 is B is the voltage drop V DROP Therefore, the supply voltage V DD is the output current I OUT Regardless of the magnitude of the minimum operating voltage V DD(MIN) This allows the device to be kept close to the ground, reducing unnecessary power consumption.

[0189] The present invention encompasses various devices and methods that can be understood as the block diagram or circuit diagram in Fig. 21 or that are derived from the above description, and is not limited to a specific configuration. Below, more specific configuration examples and embodiments will be described not to narrow the scope of the present invention, but to aid in understanding and clarify the essence and operation of the invention.

[0190] Example 2.1 23 is a block diagram of a headlamp 200A according to Example 2.1. The headlamp 200A includes a variable light distribution light source 210, a power supply circuit 220A, and a control unit 260.

[0191] The power supply circuit 220A includes a DC / DC converter 224, a current sensor 223, and a power supply control circuit 225A.

[0192] The current sensor 223 detects the output current I OUT Current detection signal V according to CS For example, the current sensor 223 includes a sense resistor Rs and an amplifier AMP1. The sense resistor Rs generates an output current I OUT In FIG. 23, the sense resistor Rs is provided on the positive output terminal OUTP side, but it may be provided on the negative output terminal OUTN side. The amplifier AMP1 amplifies the voltage drop occurring in the sense resistor Rs and outputs the current detection signal V CS This current detection signal V CS is the output current I OUT , and therefore the voltage drop V DROP When the detection gain of the current sensor 223 is A, the following formula is established. V CS =A×I OUT

[0193] The power supply control circuit 225A controls the voltage drop V DROP The current detection signal V CS Based on this, the target value V OUT(REF) and controls the DC / DC converter 224.

[0194] In the embodiment 2.1, the power supply 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 outputs a feedback voltage V FB is the internally generated reference voltage V REF A pulse signal is generated in which at least one of the pulse width, frequency, and duty cycle is adjusted so as to approach the above-mentioned value, and the DC / DC converter 224 is feedback-controlled in response to the pulse signal.

[0195] The feedback circuit 226A is connected to the output voltage V OUT From the current detection signal V CS Correction voltage V based on CMP and the feedback voltage V FB And generate the feedback voltage V FB to the feedback pin FB of the converter controller 228.

[0196] Feedback voltage V FB is the output voltage V OUT and the correction voltage V CMP It is a signal that changes depending on each and is expressed by equation (1). V FB =K1 V OUT -K2·V CMP …(1) K1,K2>0

[0197] The feedback signal V FB is the target value V REF The DC / DC converter 224 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0198] When the system is in a stable steady state, K1·V OUT -K2·V CMP =VREF Therefore, in the steady state, the output voltage V OUT is the target value V OUT(REF) is stabilized to. V OUT(REF) =(V REF +K2·V CMP ) / K1…(2)

[0199] Therefore, V CMP =V CS =A×I OUT When V OUT(REF) =(V REF +K2·A×I OUT ) / K1…(2') get. K2 / K1·A is the impedance R of the connection means 202, and V REF / K1 is V DD(MIN) If the circuit constants are determined so that V OUT(REF) =V DD(MIN) +I OUT ×R=V DD(MIN) +V DROP It can be said that:

[0200] 24 is a circuit diagram showing an example of the configuration of a feedback circuit 226A. The feedback circuit 226A includes a subtraction circuit 227 having an operational amplifier. The subtraction circuit 227 includes resistors R31 to R34 and an operational amplifier OA3. The input / output characteristics of the subtraction circuit 227 are expressed by equation (3). Vx=(R31+R32) / R31×{R34 / (R33+R34)×V CNT -R32 / (R31+R32)×V CMP …(3)

[0201] The output voltage Vx of the subtraction circuit 227 is the feedback voltage V FB Alternatively, the voltage Vx may be divided by resistors R35 and R36, and the divided voltage V FB ' may be output as a feedback voltage.

[0202] Vx=V FB If this is the case, comparing equation (1) and equation (3), K1=(R31+R32) / R31×R34 / (R33+R34) K2=(R31+R32) / R31×R32 / (R31+R32) get.

[0203] Example 2.2 25 is a block diagram of a headlamp 200B according to Example 2.2. The headlamp 200B includes a variable light distribution light source 210, a power supply circuit 220B, and a control unit 260.

[0204] The power supply circuit 220B includes a DC / DC converter 224, a power supply control circuit 225B, and a detection terminal SNS.

[0205] The detection terminal SNS is connected to the power supply terminal VDD of the array type light emitting device 212 via a detection line (direct line) LSNS independent of the connection means 202. The input impedance of the power supply control circuit 225B is sufficiently high, and no current flows through the detection line LSNS. Therefore, the detection voltage V generated at the detection terminal SNS SNS is the voltage V of the power supply terminal VDD of the array type light emitting device 212 DD is equal to.

[0206] The power supply control circuit 225B controls the output voltage V OUT and the detection voltage V of the detection terminal SNS SNS The difference between ΔV and V OUT -V SNS Based on this, the voltage drop V of the connection means 202 DROP This difference ΔV represents the voltage drop in the power supply line LVDD of the connection means 202 and the connector on the positive side.

[0207] For example, when the impedance of the positive electrode side of the connection means 202 is equal to the impedance of the negative electrode side, ΔV×2 is the voltage drop V DROPThe power supply control circuit 225B includes an amplifier AMP2, a feedback circuit 226B, and a converter controller 228. The amplifier AMP2 outputs an output voltage V OUT and detection voltage V SNS The difference is amplified and the correction voltage V CMP This correction voltage V CMP is the output current I OUT is proportional to. V CMP =B×(V OUT -V SNS )=A×I OUT

[0208] The feedback circuit 226B is connected to the output voltage V OUT to the correction voltage V CMP and the feedback voltage V FB And generate the feedback voltage V FB to the feedback pin FB of the converter controller 228.

[0209] Feedback voltage V FB is the output voltage V OUT and the correction voltage V CMP It is a signal that changes depending on each and is expressed by equation (1). V FB =K1 V OUT -K2·V CMP …(again 1)

[0210] The feedback signal V FB is the target value V REF In the steady state, the DC / DC converter 224 is controlled so that the output voltage V OUT is the target value V OUT(REF) is stabilized to. V OUT(REF) =(V REF +K2·V CMP ) / K1…(again 2)

[0211] Therefore, V CMP =A×I OUT When V OUT(REF) =(V REF +K2·A×I OUT ) / K1…(2') get. K2 / K1·A is the impedance R of the connection means 202, and V REF / K1 is V DD(MIN) If the circuit constants are determined so that V OUT(REF) =V DD(MIN) +I OUT ×R=V DD(MIN) +V DROP It can be said that:

[0212] Example 2.3 26 is a block diagram of a headlamp 200C according to Example 2.3. The headlamp 200C includes a variable light distribution light source 210, a power supply circuit 220C, and a control unit 260.

[0213] The power supply circuit 220C includes a DC / DC converter 224, a current sensor 223, and a power supply control circuit 225C.

[0214] The current sensor 223 detects the output current I OUT Current detection signal V according to CS Generate. V CS =A×I OUT

[0215] The power supply control circuit 225C includes a voltage setting circuit 230C and a converter controller 228C. The converter controller 228C has a reference voltage setting pin REF in addition to a feedback pin FB. REF Depending on the REF The converter controller 228C receives an analog reference signal S REF and directly feeds it to the internal reference voltage V REF The converter controller 228C uses the voltage VFB is the reference signal S REF Reference voltage V based on REF The DC / DC converter 224 is feedback-controlled so as to approach

[0216] The feedback pin FB of the converter controller 228C is connected to the output voltage V OUT Feedback voltage V according to FB In this example, the feedback voltage V FB is the output voltage V OUT This is the divided voltage and is expressed by the following equation (4). V FB =K1×V OUT …(4)

[0217] The voltage setting circuit 230C is a voltage drop V DROP A reference signal S according to REF and supplies it to the reference voltage setting pin REF of the converter controller 228C. In this embodiment, the voltage setting circuit 230C generates a predetermined voltage V REG and the current detection signal V CS Correction voltage V based on CMP Adding these together, the analog reference voltage V REF Generate. V REF =K2 V REG +K3·V CMP …(5)

[0218] In steady state, V REF =V FB Since this holds, we obtain equation (6). K2 V REG +K3·V CMP =K1×V OUT …(6)

[0219] Therefore, the output voltage V OUT The target value of V OUT(REF) is expressed by equation (7). V OUT(REF) =(K2 V REG +K3·V CMP ) / K1…(7)

[0220] In equation (7), V CMP =V CS =A×I OUT Substituting this, we obtain equation (8). V OUT(REF) =(K2 V REG +K3·A×I OUT ) / K1…(8) Therefore, K2 / K1×V REG =V DD(MIN) By determining the circuit constants so that K3·A / K1=R, V OUT(REF) =V DD(MIN) +R×I OUT It can be said that:

[0221] Example 2.4 27 is a block diagram of a headlamp 200D according to Example 2.4. The headlamp 200D includes a variable light distribution light source 210, a power supply circuit 220D, and a control unit 260.

[0222] The power supply circuit 220D includes a DC / DC converter 224, a power supply 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 (direct line) LSNS independent of the connection means 202.

[0223] The power supply control circuit 225D includes an amplifier AMP3, a voltage setting circuit 230D, and a converter controller 228D. The converter controller 228D has a reference voltage setting pin REF in addition to a feedback pin FB, and a reference signal S REF Depending on the REF The feedback pin of the converter controller 228D can be set to V FB =K1×V OUT is entered.

[0224] The amplifier AMP3 outputs an output voltage V OUT and detection voltage V SNSThe difference is amplified and the correction voltage V CMP This correction voltage V CMP is the output current I OUT is proportional to. V CMP =B×(V OUT -V SNS )=A×I OUT

[0225] The voltage setting circuit 230D is a voltage drop V DROP A reference signal S according to REF and supplies it to the reference voltage setting pin REF of the converter controller 228D. In this embodiment, the voltage setting circuit 230D generates a predetermined voltage V REG and the correction voltage V CMP Adding these together, the analog reference voltage V REF Generate. V REF =K2 V REG +K3·V CMP …(9)

[0226] In this power supply circuit 220D, the output voltage V OUT The target value of V OUT(REF) is expressed by equation (10). V OUT(REF) =(K2 V REG +K3·V CMP ) / K1…(10)

[0227] In equation (10), V CMP =A×I OUT Substituting this, we obtain equation (11). V OUT(REF) =(K2 V REG +K3·A×I OUT ) / K1…(11) Therefore, K2 / K1×V REG =V DD(MIN) By determining the circuit constants so that K3·A / K1=R, V OUT(REF) =V DD(MIN) +R×I OUT It can be said that:

[0228] A modification related to the second embodiment will be described.

[0229] (Variation 2.1) FIG. 28 is a diagram showing a headlamp 200 according to Modification 2.1. In the above description, the variable light distribution light source 210 includes one array-type light-emitting device 212. However, the variable light distribution light source 210 may include a plurality of array-type light-emitting devices 212. In this case, the power supply circuit 220 may be unitized (referred to as a power supply unit 222), and a plurality of power supply units 222 may be provided corresponding to the plurality of array-type light-emitting devices 212. An output terminal of each power supply unit 222 is connected to a power supply terminal of the corresponding array-type light-emitting device 212 via an individual power supply cable LVDD. Furthermore, a detection line LSNS may be provided for each pair of the power supply unit 222 and the array-type light-emitting device 212, as necessary. In this modification, the microcontroller 240 may be shared by the plurality of power supply units.

[0230] In this modification 2.1, the variable light distribution light source 210 is divided into a plurality of array-type light-emitting devices 212 with independent power supply terminals. 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 with a power cable. This allows the current flowing through the variable light distribution light source 210 to be distributed to a plurality of DC / DC converters, reducing the effect of voltage drop in each DC / DC converter and improving load responsiveness. In addition, there are more options for DC / DC converter components, power cables, and connectors, allowing for greater freedom in design.

[0231] (Variation 2.2) Fig. 29 is a diagram showing a headlamp 200 according to Modification 2.2. The array type light emitting device 212 has a plurality of internal light emitting pixels divided into a plurality of segments SEG1 to SEGn, and a plurality of power supply terminals VDD may be provided corresponding to the plurality of segments SEG1 to SEGn. The power supply circuit 220 is provided with a plurality of power supply units 222 corresponding to the plurality of power supply terminals VDD. An output terminal OUT of each power supply unit 222 is connected to a corresponding power supply terminal VDD of the array type light emitting device 212 via an individual power supply cable LVDD. Furthermore, a detection line LSNS may be provided for each power supply unit 222 as necessary.

[0232] In this modification 2.2 as well, the current flowing through the variable light distribution light source 210 can be distributed to multiple DC / DC converters, and the same effect as in modification 2.1 can be obtained.

[0233] (Variation 2.3) The power supply unit 222 may be configured with a phase-shift type converter. By adopting a phase-shift type converter, the output voltage V OUTi and output current I OUTi In addition, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I OUTi Since the load fluctuates rapidly in response to the lighting rates of multiple pixel circuits, the use of a phase-shift converter can improve the response to load fluctuations.

[0234] (Variation 2.4) Although the case has been described where power supply circuit 220 and control unit 260 are built into headlamp 200, one or both of them may be provided on the outside of the body of headlamp 200. Since variable light distribution light source 210 is a heat generating body, it is advantageous from the viewpoint of thermal design to place control unit 260, which avoids heat, inside the vehicle cabin away from variable light distribution light source 210.

[0235] (Variation 2.5) In the embodiments 2.1 to 2.4, the power supply control circuit 225 is configured with an analog circuit, but a part or the whole of the power supply control circuit 225 may be configured with a digital circuit. For example, the power supply control circuit 225 may include a microcontroller. The microcontroller outputs the current detection signal V CS Alternatively, the output voltage of the amplifier AMP3 is converted into a digital value, and the voltage drop V DROP The output voltage V is obtained by digital signal processing. OUT The target value of V OUT(REF) may be set.

[0236] (Variation 2.6) In the embodiment 2.2 or 2.4, the detection terminal SNS may be connected to the ground terminal GND of the array type light emitting device 212 via the detection line LSNS. In this case, the amplifier AMP2 or AMP3 detects the voltage V SNS and the voltage of the negative output OUTN of the DC / DC converter 224 may be amplified.

[0237] (Embodiment 3) 30 is a block diagram of a lighting system 100 according to embodiment 3. The lighting system 100 is an ADB lamp system, and includes a battery 102, a host controller 104, and a headlamp 200.

[0238] The upper controller 104 generates a light distribution command for the headlamp 200. The light distribution command may include a lighting command and additional information. The lighting command may include a signal instructing high beam or low beam to be on or off. A basic light distribution to be formed by the headlamp 200 is determined in response to the lighting command. The additional information may include data on an area where the high beam should not be irradiated (shading area), and information such as the vehicle speed and steering angle. The basic light distribution is corrected in response to the additional information, and a final light distribution is determined. The upper controller 104 may be configured as an ECU on the vehicle side, or as an ECU on the lamp side built into the headlamp 200.

[0239] The headlamp 200 is an ADB lamp that includes a variable light distribution light source 210, a power supply circuit 220, and a control unit 260.

[0240] The variable light distribution light source 210 includes a plurality of pixels arranged in an array, and each pixel can be individually controlled to be turned on or off. In the headlamp 200, the plurality of pixels are controlled to be turned on or off so as to obtain a desired light distribution.

[0241] More specifically, the variable light distribution 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 plurality of pixel circuits PIX1 to PIXn.

[0242] A pixel circuit PIXj (1≦j≦n) includes a light emitting element 213_j and a current source 214_j that are provided in series between a power supply terminal VDD and a ground terminal (ground line) GND. The 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 spatially arranged in an array (matrix).

[0243] The 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 turned on.

[0244] The interface circuit 216 controls the on / off of the current sources 214_1 to 214_n in response to a 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 that instructs the on / off of all the pixels.

[0245] The interface circuit 216 also detects the voltage drop (i.e., forward voltage) V of the light emitting element 213 of each of the pixel circuits PIX1 to PIXn. F1 ~V Fn Monitor the forward voltage VF1 ~V Fn In this embodiment, the data S3A is transmitted to the power supply circuit 220 via the control unit 260 as data S3B.

[0246] The power supply circuit 220 supplies power to the variable light distribution light source 210. The power supply circuit 220 includes a constant voltage output converter, and supplies a stabilized power supply voltage V DD Supply voltage V DD V F +V SAT It is determined based on the voltage, typically around 4 to 5 V. F is the forward voltage of the light emitting element 213, V SAT is the minimum operating voltage of the current source 214. Therefore, the power supply circuit 220 is connected to a battery voltage V BAT It can be configured with a step-down converter (Buck converter) that steps down the

[0247] The control unit 260 receives a light distribution command S1 from the upper controller 104, generates a control signal S2 according to the light distribution command S1, and transmits 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 controls the PWM of the 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 (for example, 100 to 400 Hz), and therefore the PWM period is several milliseconds to several tens of milliseconds (ms).

[0248] Next, a description will be given of the configuration of the power supply circuit 220. The power supply circuit 220 includes output terminals AP / AN, a ground terminal GND, a DC / DC converter 224, and a power supply control circuit 225.

[0249] 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 a power cable 204. The power supply cable 204 includes a power supply line LVDD and a ground line LGND. A 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 the output terminal AP and the power supply line LVDD, and a 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 the output terminal AN and the ground line LGND. A voltage V from the battery is input to the input of the DC / DC converter 224. BAT is supplied.

[0250] The power supply control circuit 225 receives the data S3B from the control unit 260. Based on the received data S3B, the power supply control circuit 225 controls the controlled voltage V CNT The target value of V CNT(REF) Determine the controlled voltage V CNT is the target value V CNT(REF) The DC / DC converter 224 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0251] As will be described later in detail, the controlled voltage V CNT is the power supply voltage V of the array type light emitting device 212 DD Alternatively, the output voltage V OUT may be also possible.

[0252] Controlled voltage V CNT The target value of V CNT(REF) is the forward voltage V of the light emitting element 213 of all channels F1 ~V Fn Maximum value of V F(MAX) For example, the data S3B received by the power supply control circuit 225 may correspond to the forward voltages V F1 ~V Fn In this case, the power supply control circuit 225 may include a forward voltage V F1 ~V Fn Maximum value of V F(MAX) Obtain the maximum value V F(MAX) Based on this, the target value VCNT(REF) Alternatively, the control unit 260 may generate a forward voltage V F1 ~V Fn Maximum value of V F(MAX) Obtain the maximum value V F(MAX) The data S3B including the above may be transmitted to the power supply control circuit 225.

[0253] The above is the configuration of the lighting system 100. Figures 31(a) and (b) are diagrams showing the operation of the lighting system 100. Here, the controlled voltage V CNT is the power supply voltage V of the array type light emitting device 212. DD Let us assume that.

[0254] 31(a) and (b) show the operation of different components of the lighting system 100. In FIG. 31(a), the forward voltage V Fi is the maximum value V F(MAX) The controlled voltage V CNT The power supply voltage V DD The target value of V DD(REF) teeth, V DD(REF) =V D +V Fi(MAX) +α V D is the voltage drop of the current source 214, and α is a margin.

[0255] In FIG. 31(b), the forward voltage V of the j-th pixel PIXj of the array type light emitting device 212 Fj is the maximum value V F(MAX) The controlled voltage V CNT The power supply voltage V DD The target value of V DD(REF) teeth, V DD(REF) =V D +V Fj +α It is determined based on.

[0256] As shown in Figure 31(a) and (b), the forward voltage V FUsing this, the target value V DD(REF) By determining the value V DD(SPEC) than the power supply voltage V DD This allows the power consumption of the array type light emitting device 212 to be reduced.

[0257] Fig. 32 is a diagram showing the operation of the lighting system 100. Fig. 32 shows how one lighting system 100 operates in different temperature environments. The forward voltage V F has temperature dependency, and decreases as the temperature increases. According to this embodiment, the controlled voltage V DD The target value of V DD(REF) Since the power consumption can be reduced, the power consumption can be reduced.

[0258] The above is the operation of the lighting system 100. According to this lighting system 100, the voltage drop V F The power consumption can be reduced by reflecting the information on the forward voltage V of the light emitting element 213 during actual operation in the feedback control of the power supply circuit 220 in real time. F By monitoring the actual minimum operating voltage V DD(MIN) The minimum operating voltage V DD(MIN) reflects individual variations and temperature fluctuations of the array-type light-emitting device 212, and is a value V DD(SPEC) Therefore, the exact minimum operating voltage V DD(MIN) Based on this, the operating conditions of the power supply circuit 220 are dynamically determined, so that the power supply voltage V DD can be lowered, and power consumption can be reduced.

[0259] The present invention encompasses various devices and methods that can be understood as the block diagram or circuit diagram in Figure 30 or that are derived from the above description, and is not limited to a specific configuration. Below, more specific configuration examples and embodiments will be described not to narrow the scope of the present invention, but to aid in understanding and clarify the essence and operation of the invention.

[0260] Example 3.1 33 is a block diagram of a headlamp 200A according to Example 3.1. The headlamp 200A includes a variable light distribution light source 210, a power supply circuit 220A, and a control unit 260.

[0261] The power supply circuit 220A includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225A. The power supply control circuit 225A includes a feedback circuit 226A, a converter controller 228, and a voltage setting circuit 230.

[0262] The converter controller 228 can use a commercially available DC / DC converter control IC (Integrated Circuit). The converter controller 228 controls the feedback voltage V FB is the internally generated reference voltage V REF A pulse signal is generated in which at least one of the pulse width, frequency, and duty cycle is adjusted so as to approach the above-mentioned value, and the DC / DC converter 224 is feedback-controlled in response to the pulse signal.

[0263] The voltage setting circuit 230 receives data S3B generated by the array type light emitting device 212. Based on the received data S3B, the voltage setting circuit 230 sets the correction voltage V CMP The feedback circuit 226A generates the output voltage V OUT The controlled voltage V CNT and the correction voltage V CMP Based on this, the feedback voltage V FBand supplies it to the feedback pin FB of the converter controller 228. FB is the controlled voltage V CNT and the correction voltage V CMP It is a signal that changes depending on each and is expressed by equation (1). V FB =K1 V CNT +K2·V CMP …(1) where K1 is a constant >0 and K2 is a non-zero constant. Here, K2<0. The converter controller 228 calculates the feedback signal V FB is the target value V REF The DC / DC converter 224 is controlled so that the output voltage Vout approaches the reference voltage Vout.

[0264] When the system is in a stable steady state, K1·V CNT +K2·V CMP =V REF Therefore, in the steady state, the controlled voltage V CNT is the target value V CNT(REF) is stabilized to. V CNT(REF) =(V REF -K2·V CMP ) / K1…(2)

[0265] In this Example 3.1, the controlled voltage V CNT is the voltage V of the power supply terminal VDD of the array type light emitting device 212 DD It is.

[0266] The detection terminal SNS of the power supply circuit 220A is connected to the power supply terminal VDD of the array type light emitting device 212 via a detection line (direct line) LSNS that is independent of the power cable 204 (power supply line LVDD). The input impedance of the feedback circuit 226A is sufficiently high, and no current flows through the detection line LSNS. Therefore, the detection voltage V SNS is the voltage V of the power supply terminal VDD of the array type light emitting device 212 DD The feedback circuit 226A receives the detection voltage VSNS is the controlled voltage V CNT Therefore, the power supply voltage V DD The target value of V DD(REF) is expressed by equation (3). V DD(REF) =(V REF -K2·V CMP ) / K1…(3) In other words, the correction voltage V CMP By changing the power supply voltage V DD The target value of V DD(REF) can be varied.

[0267] The above is the configuration of the headlamp 200A. Next, the operation of the headlamp 200A will be described. FIG. 34 is an operation waveform diagram of the headlamp 200A in FIG. 33. In the period T0, the correction voltage V CMP During this period T0, the power supply voltage V DD teeth, V DD(REF)_0 =V REF / K1 The output voltage V OUT is the power supply voltage V DD The voltage drop V in the power supply line LVDD and connectors, etc. DROP This voltage is higher than the reference voltage by 1 V, and is expressed by equation (4). V OUT =V DD +V DROP =V DD +R×I OUT …(4) R is the impedance of the power supply line LVDD and the connector. When the headlamp 200A is turned on, the operating current I OUT On a long time scale, the output current I OUT The average value of varies depending on the light distribution formed by the headlamp 200A. Also, on a short time scale, the output current I OUT The instantaneous value of fluctuates with the PWM control period. Figure 34 shows the output current I OUT In Example 3.1, the power supply voltage V DDis regulated and the output voltage V OUT is the output current I OUT It changes depending on.

[0268] During the period T1, the correction voltage V CMP is a positive value V CMP1 During this period T1, the power supply voltage V DD The target value of V DD(REF)_1 teeth, V DD(REF)_1 =(V REF -K2·V CMP1 ) / K1 Since K2 is a negative constant, the power supply voltage V DD The target value of V DD(REF) teeth, V DD(REF)_1 =(V REF +|K2|·V CMP1 ) / K1 The target value for the period T0 is V DD(REF)_0 From this, |K2| V CMP1 This voltage is offset in the positive direction by / K1.

[0269] During the period T2, the correction voltage V CMP to a higher value V CMP2 When this is set, the power supply voltage V DD The target value of V DD(REF)_2 teeth, V DD(REF)_2 =(V REF -K2·V CMP2 ) / K1 The target value for the period T0 is V DD(REF)_0 From this, |K2| V CMP2 This voltage is offset in the positive direction by / K1.

[0270] The above is the operation of the headlamp 200A. According to the headlamp 200A, the correction voltage V CMP By changing the voltage V DD The target value of V DD(REF) can be flexibly set.

[0271] Next, configuration examples of the voltage setting circuit 230 and the feedback circuit 226A will be described.

[0272] 35 is a circuit diagram showing an example of the configuration of a feedback circuit 226A. This feedback circuit 226A is a subtraction circuit having an operational amplifier, and includes resistors R31 to R34 and an operational amplifier OA3. The input / output characteristics of this feedback circuit 226A are expressed by equation (5). V FB =(R31+R32) / R31×{R34 / (R33+R34)×V CNT -R32 / (R31+R32)×V CMP …(5)

[0273] Comparing equations (1) and (5), K1=(R31+R32) / R31×R34 / (R33+R34) K2=-(R31+R32) / R31×R32 / (R31+R32) get.

[0274] The feedback circuit 226A may be configured as an adder circuit using an operational amplifier. In this case, K1>0, K2>0. The correction voltage V CMP When is positive, the correction voltage V CMP Depending on the voltage V CNT The target value of can be shifted to the lower potential side.

[0275] 36 is a circuit diagram showing a configuration example 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 controls the forward voltage V F According to the data S3B, the correction voltage V CMP Specify the digital setting value D CMP Using the microcontroller 240, the correction voltage V CMP It is now possible to control the above using software.

[0276] The D / A converter 234 converts the set value D CMP , the analog correction voltage V CMP Convert to the correction voltage V CMP is supplied to the feedback circuit 226A via a buffer 236. If the output impedance of the D / A converter 234 is sufficiently low, the buffer 236 can be omitted. If a microcontroller 240 with a built-in D / A converter is used, the D / A converter 234 will be present inside the microcontroller 240.

[0277] Example 3.2 37 is a block diagram of a headlamp 200B according to Example 3.2. The configuration of the headlamp 200B will be described, focusing on the differences from Example 3.1. The headlamp 200B includes a variable light distribution light source 210, a power supply circuit 220B, and a control unit 260. In Example 3.2, the configuration of the power supply circuit 220B is different from that of the power supply circuit 220A in Example 3.1.

[0278] The power supply circuit 220B includes an output terminal OUT, a DC / DC converter 224, and a power supply control circuit 225B. The power supply control circuit 225B includes a feedback circuit 226B, a converter controller 228, and a voltage setting circuit 230.

[0279] In Example 3.2, the output voltage V OUT is the controlled voltage V CNT The feedback circuit 226B has an output voltage V OUT is the controlled voltage V CNT Therefore, the output voltage V OUT The target value of V OUT(REF) is expressed by the following equation (6): The feedback circuit 226B may be a subtraction circuit, similar to the feedback circuit 226A in the embodiment 3.1. V OUT(REF) =(V REF -K2·V CMP ) / K1…(6)

[0280] Correction voltage V CMP is the target value V OUT(REF) But, V F(MAX) +V D +α+V DROP It is generated so that V DROP is the voltage drop on the power line LVDD and the connector, and V DROP =I OUT ×R. I OUT Since it fluctuates from moment to moment, the voltage drop V DROP The value of the maximum current I OUT(MAX) It may be decided based on the assumption.

[0281] Alternatively, as explained in Example 3.3, the voltage drop V DROP Detect the actual voltage drop V DROP , the correction voltage V CMP It may be reflected in the

[0282] The above is the configuration of the headlamp 200B. Next, the operation of the headlamp 200B will be described. FIG. 38 is an operation waveform diagram of the headlamp 200B in FIG. 37. In the period T0, the correction voltage V CMP is 0V. The output voltage V OUT teeth, V OUT(REF)_0 =V REF / K1 is stabilized to.

[0283] The power supply voltage V supplied to the array type light emitting device 212 DD is the output voltage V OUT The voltage drop V in the power supply line LVDD and connectors, etc. DROP This voltage is lower than the reference voltage by 1 V, and is expressed by equation (7). V DD =V OUT -V DROP =V OUT -R×I OUT …(7) R is the impedance of the power supply line LVDD and the connector. When the headlamp 200B is turned on, the operating current I OUTTherefore, in Example 3.2, the output voltage V OUT is regulated, and the power supply voltage V DD is the output current I OUT Varies depending on.

[0284] During the period T1, the correction voltage V CMP is a positive value V CMP1 During this period T1, the output voltage V OUT The target value of V OUT(REF)_1 teeth, V OUT(REF)_1 =(V REF -K2·V CMP1 ) / K1 Since K2 is a negative constant, the output voltage V OUT The target value of V OUT(REF) teeth, V OUT(REF)_1 =(V REF +|K2|·V CMP1 ) / K1 The target value for the period T0 is V OUT(REF)_0 From this, |K2| V CMP1 This voltage is offset in the positive direction by / K1.

[0285] During the period T2, the correction voltage V CMP to a higher value V CMP2 When this is set, the output voltage V OUT The target value of V OUT(REF)_2 teeth, V OUT(REF)_2 =(V REF -K2·V CMP2 ) / K1 The target value for the period T0 is V DD(REF)_0 From this, |K2| V CMP2 This voltage is offset in the positive direction by / K1.

[0286] The above is the operation of the headlamp 200B. According to the headlamp 200B, the correction voltage V CMP In response to this, the output voltage V OUT can be flexibly set, and thus the voltage V DD can be flexibly set.

[0287] Example 3.3 39 is a block diagram of a headlamp 200C according to Example 3.3. The configuration of the headlamp 200C will be described, focusing on the differences from Example 3.2.

[0288] The headlamp 200C includes a variable light distribution light source 210, a power supply circuit 220C, and a control unit 260. In the embodiment 3.3, the configuration of the power supply circuit 220C is different from that of the power supply circuit 220B in the embodiment 3.2.

[0289] The configuration of the power supply circuit 220C will be described below. The power supply circuit 220C includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225C.

[0290] The power supply control circuit 225C includes a feedback circuit 226C, a converter controller 228, and a voltage setting circuit 230.

[0291] The feedback circuit 226C includes a controlled voltage V CNT As the output voltage V OUT The feedback circuit 226C also receives the power supply voltage V DD Furthermore, the feedback circuit 226C receives the correction voltage V generated by the voltage setting circuit 230. CMP is entered.

[0292] The feedback circuit 226C outputs three voltages V OUT ,V SNS ,V CMP Based on this, the feedback voltage V FB The feedback circuit 226C generates V OUT and V SNS Based on the difference between the voltage drop V DROP =V OUT -V SNS Detect.

[0293] The feedback voltage V generated by the feedback circuit 226C FB is expressed by equation (8). V FB =K1 V OUT +K2·V CMP +K3·V DROP …(8)

[0294] The above is the configuration of the headlamp 200C. In this headlamp 200C, the output voltage V OUT The target value of V OUT(REF) is expressed by equation (9). V OUT(REF) =(V REF -K2·V CMP -K3·V DROP ) / K1…(9) If K2<0,K3<0, V OUT(REF) =(V REF +|K2|·V CMP +|K3|·V DROP ) / K1…(9') When |K3|=K1 holds, V OUT(REF) =(V REF +|K2|·V CMP ) / K1+V DROP …(9'')

[0295] According to Example 3.3, the actually detected voltage drop V DROP Based on this, the output voltage V OUT The target value of V OUT(REF) By optimizing the gain K3, the voltage drop of the ground line LGND can be corrected.

[0296] 40 is a functional block diagram of the feedback circuit 226C. The feedback circuit 226C may include three subtraction circuits SUB1 to SUB3. The subtraction circuit SUB1 subtracts the output voltage V OUT to detection voltage V SNS Subtract the voltage drop V DROP The subtraction circuit SUB2 calculates the output voltage V OUT Voltage drop from VDROP The subtraction circuit SUB3 subtracts the output voltage V OUT -V DROP Then, the correction voltage V CMP The order of subtraction may be reversed.

[0297] Example 3.4 41 is a circuit diagram of a headlamp 200D according to Example 3.4. The headlamp 200D includes a variable light distribution light source 210, a power supply circuit 220D, and a control unit 260.

[0298] The configuration of the power supply circuit 220D will be described below. The power supply circuit 220D includes an output terminal OUT, a detection terminal SNS, a DC / DC converter 224, and a power supply control circuit 225D.

[0299] The power supply 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, and receives a reference signal S REF Depending on the REF The converter controller 228D is capable of setting the reference signal S REF is received as a digital signal, and the internal voltage source generates a reference voltage V REF Alternatively, the converter controller 228D may generate an analog reference signal S REF and directly feeds it to the internal reference voltage V REF The converter controller 228D may utilize the voltage V FB is the reference signal S REF Reference voltage V based on REF The DC / DC converter 224 is feedback-controlled so as to approach

[0300] The voltage setting circuit 230D sets the reference signal S REF and supplies it to the reference voltage setting pin REF of the converter controller 228D. REFWhen V is an analog voltage, the voltage setting circuit 230D can be configured similarly to that shown in FIG. CMP Let S be the reference signal. REF The reference signal S REF If the set value D is a digital signal, the voltage setting circuit 230D can be configured only by the microcontroller 240 of FIG. CMP , the reference signal S REF This can be read as follows.

[0301] The feedback circuit 226D is a control target voltage V CNT Feedback voltage V according to FB and provides it to the feedback pin FB of the converter controller 228D.

[0302] As in Example 3.2, the controlled voltage V CNT is the output voltage V OUT In this case, the feedback voltage V FB is expressed by equation (10). V FB =K1 V OUT …(10)

[0303] As in the embodiment 3.1, the power supply circuit 220D and the variable light distribution light source 210D are connected by a detection line LSNS, and the detection voltage V SNS (=V DD ) to be controlled by the voltage V CNT In this case, the feedback voltage V FB is expressed by equation (11). V FB =K1 V SNS =K1 V DD …(11)

[0304] As in Example 3.3, the output voltage V OUT The controlled voltage V CNT and the voltage drop V on the power supply line LVDD DROP The voltage after correction is called the feedback voltage V FB In this case, the feedback voltage V FB is expressed by equation (12). V FB =K1 V OUT +K3·V DROP …(12)

[0305] As explained in Example 3.3, the voltage drop V DROP The power supply circuit 220D and the variable light distribution light source 210D are connected by a detection line LSNS, and V OUT and V SNS It can be obtained by calculating the difference between

[0306] According to Example 3.4, the same effects as those of Examples 3.1 to 3.3 can be obtained.

[0307] In some of the above-mentioned embodiments, the microcontroller may have the following functions: FIG.

[0308] (Anomaly detection function) The microcontroller 240 controls the controlled voltage V CNT and the target value V based on data S3B CNT(REF) The converter controller 228 may obtain the error ΔV of the controlled voltage V CNT The target value V CNT(REF) If no deviation from the normal voltage V is detected, the microcontroller 240 CNT and the target value V CNT(REF) By monitoring the error, abnormal conditions can be detected (fail judgement).

[0309] The microcontroller 240 includes a plurality of analog input pins AN1 to ANX, a multiplexer MUX, an A / D converter 242, a processor (core) 244, and an interface circuit 246.

[0310] The input of the built-in A / D converter 242 can be switched by a multiplexer MUX, and the voltage of any analog input pin can be converted into a digital value. The interface circuit 246 can also receive data S3B. In addition to an external analog voltage, the A / D converter 242 may also be able to receive an internal reference voltage or power supply voltage of the microcontroller 240.

[0311] One of the analog input pins AN of the microcontroller 240 is connected to the controlled voltage V CNT is input. The controlled voltage V CNT As mentioned above, the output voltage V OUT or the power supply voltage V DD The A / D converter 242 may be a CNT A digital value Dx of

[0312] The processor 244 executes a software program to set a set value D in response to the data S3B received by the interface circuit 246. CMP (or the reference signal S REF ) and outputs it from the digital output pin DOUT.

[0313] Furthermore, the processor 244 determines the controlled voltage V CNT The target value of V CNT(REF) Then, the processor 244 calculates a digital value Dy indicating the abnormality. Then, the processor 244 calculates the difference between the digital value Dx obtained by the A / D converter 242 and the digital value Dy obtained by the calculation, and compares the difference with a threshold value. When Dx-Dy exceeds the threshold value, the processor 244 determines that an abnormality has occurred. When the processor 244 determines that an abnormality has occurred, the processor 244 may output a flag indicating an abnormality from the general-purpose output pin GPIO.

[0314] In one embodiment, when the microcontroller 240 determines that an abnormality has occurred, the set value D CMP (Reference signal S REF ) may be fixed to a predetermined value. By setting the predetermined value high, the controlled voltage V CNT The target value of VCNT(REF) In this way, in an abnormal state, a high voltage is forcibly supplied to the array type light emitting device, so that the light can be maintained and the device functions as a fail-safe.

[0315] (A / D converter calibration) In many cases, the accuracy of the A / D converter 242 built into the microcontroller 240 is not very high. A low-accuracy A / D converter 242 leads to a decrease in the performance of the above-mentioned fail-safe function. Therefore, the following process may be performed in the manufacturing process or inspection process of the headlamp 200.

[0316] 43 is a diagram explaining the calibration of the A / D converter built into the microcontroller. An analog signal with a known voltage level is input to the analog input pin AN, and the voltage level is switched between at least two values ​​AV and BV. Then, the two voltage levels AV and BV are converted into digital values ​​Aad and Bad by the A / D converter 242.

[0317] Then, 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 ​​to obtain a value ΔV / Δad, which is stored in a non-volatile manner as the correction parameter α. In addition, the offset value ZEROad in FIG. 43 is obtained and stored in a non-volatile manner as the correction parameter β. The offset value ZEROad may be found from the measurement results at two points, or may be obtained by inputting 0V to the A / D converter 242.

[0318] After the headlamp 200 is shipped, the processor 244 of the microcontroller 240 corrects the output x of the A / D converter 242 using the parameters α and β. The corrected true value y can be found by the following equation. y=(x-β)×α

[0319] The microcontroller 240 may leave as a log information that is useful for analyzing the headlamp 200 and developing new products. Examples of information that the microcontroller 240 should store as a log will be described below.

[0320] ·Temperature information The microcontroller 240 logs temperature information obtained from an external or internal temperature sensor, which may include maximum, minimum, and average temperatures.

[0321] Power supply voltage information The microcontroller 240 logs information about various power supply voltages provided externally and / or generated by the internal power supply circuitry. The voltage information may include maximum voltages, minimum voltages, and average voltages.

[0322] Measurement information when an abnormality is detected When an abnormality is detected, the microcontroller 240 records the time when the abnormality occurred and the type of the abnormality as history, and at the same time, records accompanying information such as the temperature and power supply voltage at the time when the abnormality occurred as a log.

[0323] -Accumulated operating time information The microcontroller 240 records information on the accumulated operating time since shipment from the factory. The accumulated operating time may include information such as the accumulated operating time of the power supply circuit 220 and the accumulated operating time of the variable light distribution light source 210 including the array-type light emitting device 212, using various power supply voltages supplied from outside and / or generated by the built-in power supply circuit.

[0324] A modification related to the third embodiment will be described.

[0325] (Variation 3.1) FIG. 44 is a diagram showing a headlamp 200 according to Modification 3.1. In the above description, the variable light distribution light source 210 includes one array-type light-emitting device 212, but the variable light distribution light source 210 may include a plurality of array-type light-emitting devices 212. In this case, the power supply circuit 220 may be unitized (referred to as a power supply unit 222), and a plurality of power supply units 222 may be provided corresponding to the plurality of array-type light-emitting devices 212. An output terminal of each power supply unit 222 is connected to a power supply terminal of the corresponding array-type light-emitting device 212 via an individual power supply cable LVDD. Furthermore, a detection line LSNS may be provided for each pair of the power supply unit 222 and the array-type light-emitting device 212, as necessary. In this modification, the microcontroller 240 may be shared by the plurality of power supply units.

[0326] In this modification 3.1, the variable light distribution light source 210 is divided into a plurality of array-type light-emitting devices 212 with independent power supply terminals. 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 with a power cable. This allows the current flowing through the variable light distribution light source 210 to be distributed to a plurality of DC / DC converters, reducing the effect of voltage drop in each DC / DC converter and improving load responsiveness. In addition, there are more options for DC / DC converter components, power cables, and connectors, allowing for greater freedom in design.

[0327] (Variation 3.2) Fig. 45 is a diagram showing a headlamp 200 according to Modification 3.2. In the array type light emitting device 212, a plurality of internal light emitting pixels are divided into a plurality of segments SEG1 to SEGn, and a plurality of power supply terminals VDD may be provided corresponding to the plurality of segments SEG1 to SEGn. In the power supply circuit 220, a plurality of power supply units 222_1 to 222_n are provided corresponding to the plurality of power supply terminals VDD. An output terminal OUT of each power supply unit 222 is connected to a corresponding power supply terminal VDD of the array type light emitting device 212 via an individual power supply cable LVDD. In addition, a detection line LSNS may be provided for each power supply unit 222 as necessary.

[0328] In this modification 3.2 as well, the current flowing through the variable light distribution light source 210 can be distributed to multiple DC / DC converters, and the same effect as in modification 3.1 can be obtained.

[0329] (Variation 3.3) The power supply unit 222 may be configured with a phase-shift type converter. By adopting a phase-shift type converter, the output voltage V OUTi and output current I OUTi In addition, when PWM control is performed in the pixel circuit of the array-type light-emitting device 212, the output current I OUTi Since the load fluctuates rapidly in response to the lighting rates of multiple pixel circuits, the use of a phase-shift converter can improve the response to load fluctuations.

[0330] (Variation 3.4) Although the case has been described where power supply circuit 220 and control unit 260 are built into headlamp 200, one or both of them may be provided on the outside of the body of headlamp 200. Since variable light distribution light source 210 is a heat generating body, it is advantageous from the viewpoint of thermal design to place control unit 260, which avoids heat, inside the vehicle cabin away from variable light distribution light source 210.

[0331] (Variation 3.5) The power supply control circuit 225 may receive the data S3 output from the interface circuit 216 directly without passing through the control unit 260.

[0332] (Variation 3.6) The power supply control circuit 225 controls the forward voltage V F1 ~V Fn The power supply control circuit 225 may determine the target value based on the maximum value of the forward voltage V of the pixel that is actually turned on among the multiple pixel circuits PIX. F The target value may be determined based on the maximum value of

[0333] (Variation 3.7) An array type light emitting device is a device that controls the forward voltage V F The maximum value of V F(MAX) It may be measured in advance and stored in the internal non-volatile memory. F(MAX) may be the maximum value for all pixels and the entire temperature range. Alternatively, the forward voltage V F(MAX) and transmit data including a maximum value according to the current temperature.

[0334] The embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments without departing from the spirit of the present invention defined in the claims. [Industrial Applicability]

[0335] The present disclosure relates to a vehicle lamp. [Explanation of symbols]

[0336] 100...lighting system, 102...battery, 104...host controller, 200...headlamp, 202...connection means, 204...power cable, 206...connector, 210...variable light distribution 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 supply 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. an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and spatially arranged in a matrix; a power supply circuit for supplying power to the array-type light-emitting device; a connection means including a power cable for connecting the power supply circuit and the array type light emitting device; Equipped with The power supply circuit includes: a DC / DC converter whose output is connected to the array-type light-emitting device via the connection means; a power supply control circuit that acquires a voltage drop across the connection means, sets a target value in accordance with the voltage drop across the connection means, and controls the DC / DC converter so that an output voltage of the DC / DC converter approaches the target value; A lighting system comprising:

2. the power supply circuit further includes a current sensor that generates a current detection signal corresponding to an output current of the DC / DC converter; 2. The lighting system according to claim 1, wherein the power supply control circuit sets the target value in response to the current detection signal.

3. the power supply circuit further includes a detection terminal connected to a power supply terminal of the array type light emitting device via a detection line independent of the power supply cable; 2. The lighting system according to claim 1, wherein the power supply control circuit obtains the voltage drop across the connection means based on a difference between an output voltage of the DC / DC converter and a detected voltage at the detection terminal.

4. The power supply control circuit includes: a feedback circuit that generates a feedback voltage based on an output voltage of the DC / DC converter and a correction voltage corresponding to the voltage drop of the connection means; a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter so that the feedback voltage approaches a predetermined reference voltage; 4. The lighting system according to claim 1, further comprising:

5. The power supply control circuit includes: a voltage setting circuit for generating a reference signal corresponding to the voltage drop across the connection means; a converter controller having a feedback pin for receiving a feedback voltage corresponding to the output voltage and a reference voltage setting pin for receiving the reference signal, the converter controller controlling the DC / DC converter so that the feedback voltage approaches a reference voltage based on the reference signal; 4. The lighting system according to claim 1, further comprising:

6. A power supply circuit for supplying power to an array-type light-emitting device including a plurality of pixel circuits electrically connected in parallel and spatially arranged in a matrix, the power supply circuit comprising: a DC / DC converter whose output is connected to the array-type light-emitting device via a connection means including a power cable; a current sensor for generating a current detection signal corresponding to an output current of the DC / DC converter; a converter controller having a feedback pin and controlling the DC / DC converter so that a feedback voltage input to the feedback pin approaches a predetermined reference voltage; a feedback circuit that supplies a feedback signal corresponding to an output voltage of the DC / DC converter and the current detection signal to the feedback pin of the converter controller; A power supply circuit comprising:

7. A variable light source including an array type light emitting device; a power supply circuit for supplying power to the array-type light-emitting device; Equipped with the array-type light-emitting device includes a plurality of pixel circuits that are electrically connected in parallel and spatially arranged in a matrix, each including a light-emitting element and a current source that are connected in series, and is configured to obtain data relating to a voltage drop of a plurality of light-emitting elements included in the plurality of pixel circuits and transmit the data to an external 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; a power supply control circuit that controls the DC / DC converter so that a controlled voltage approaches a target value according to the data; A lighting system comprising:

8. 8. The lighting system according to claim 7, wherein the target value is based on a maximum value of a voltage drop of the plurality of light-emitting elements.

9. The power supply control circuit includes: a voltage setting circuit for generating a correction voltage according to the data; a feedback circuit that generates a feedback voltage based on the controlled voltage and the correction voltage; a converter controller that receives the feedback voltage at a feedback pin and controls the DC / DC converter so that the feedback voltage approaches a predetermined reference voltage; 9. The lighting system according to claim 7 or 8, further comprising:

10. The voltage setting circuit includes: a microcontroller that generates a digital set point in response to said data; a D / A converter for converting the set value into an analog correction voltage; 10. The lighting system according to claim 9, further comprising:

11. The power supply control circuit includes: a voltage setting circuit for generating a reference signal according to the data; a converter controller having a feedback pin for receiving a feedback voltage corresponding to the controlled voltage and a reference voltage setting pin for receiving the reference signal, the converter controller controlling the DC / DC converter so that the feedback voltage approaches a reference voltage based on the reference signal; 8. The lighting system according to claim 7, further comprising:

12. 12. The lighting system according to claim 11, wherein the voltage setting circuit includes a microcontroller that generates a digital set value in response to the data, and the reference voltage is in response to the set value.

13. the power supply circuit further includes a detection terminal connected to a power supply terminal of the array type light emitting device via a detection line independent of the power supply cable; 13. The lighting system according to claim 7, wherein the controlled voltage is a detection voltage generated at the detection terminal.

14. 13. The lighting system according to claim 7, wherein the controlled voltage is an output voltage of the DC / DC converter.

15. a control unit connected to an interface circuit of the array-type light-emitting device and controlling on / off of the plurality of pixel circuits of the array-type light-emitting device; 15. The lighting system according to claim 7, wherein the power supply control circuit receives the data via the control unit.

16. 13. The lighting system according to claim 10, wherein the microcontroller obtains an error between the controlled voltage and the target value based on the data.

17. 17. The lighting system according to claim 16, wherein the microcontroller determines that an abnormality has occurred when an error between the controlled voltage and the target value exceeds a predetermined threshold value.

18. 18. The lighting system according to claim 17, wherein when the microcontroller judges that an abnormality has occurred, the setting value is fixed to a predetermined value.

19. 13. The lighting system according to claim 10, wherein the microcontroller stores a history of the data.

20. 13. The lighting system according to claim 10, further comprising a temperature sensor, wherein the microcontroller stores information relating to the temperature acquired by the temperature sensor.

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