Lighting device

Abstract

To mount both functions of rank detection and temperature detection while suppressing an increase in cost.SOLUTION: The lighting device includes a light source part 2 having a light-emitting element 21, a rank detection element 22 for identifying the rank of the light-emitting element 21, and a temperature detection element 23, and a drive part 31 for supplying a drive current to the light-emitting element 21. And a control part 32 which detects the temperature around the light emitting element 21 from the temperature detection element 23 and adjusts the drive current according to the rank and the detection result of the temperature, and the light source part 2 includes a switching circuit 24 controlled according to the drive current, and alternatively connects the rank detection element 22 and the temperature detection element 23 to the control part 32 via the switching circuit 24.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lighting device. [Background technology]

[0002] In lighting control devices for lighting devices such as vehicle lamps, in order to drive a light source configured by connecting light-emitting elements such as LEDs (Light Emitting Diodes) in series, a voltage supply circuit supplies a drive voltage and a constant current circuit is provided in the light source to control the constant current. However, light-emitting elements vary in luminance, resulting in different luminance even with the same drive current. Therefore, the light-emitting elements are ranked according to the magnitude of luminance relative to the drive current (light-emitting characteristics), and a rank resistor (BIN resistor) having a resistance value corresponding to the rank is provided, and the magnitude of the drive current is adjusted by detecting the resistance value of the rank resistor. Furthermore, the light-emitting element's luminance characteristics deteriorate as its temperature rises due to light emission. Therefore, a temperature detection element such as a thermistor is provided to detect the temperature of the light-emitting element, and the magnitude of the drive current is adjusted based on the temperature detection element.

[0003] Patent Document 1 discloses an in-vehicle lamp having a light source unit and an in-vehicle light source lighting device that controls the lighting of the light source unit. The in-vehicle light source lighting device is connected to the light source unit via a connector, and the light source unit includes an LED as a light source and a status detection element that detects the status of the LED. The status detection element is a thermistor that measures the temperature of the LED or a rank resistor that indicates the rated current value of the LED, and both ends of the status detection element are connected to connector terminals, which are then connected to the connector terminals on the in-vehicle light source lighting device side by a connector harness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-119814 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to maintain a constant light emission brightness with higher reliability, it may be desirable to provide both a rank resistor and a thermistor as a status detection element. However, the above technology only lists a rank resistor and a thermistor as examples of a status detection element, and does not disclose providing both. When both rank detection and temperature detection functions are mounted on a light source board on which a light-emitting element is mounted, connector terminals, connector harnesses, noise filters, etc. must be provided for each. The increase in the number of connectors, etc., when implementing both functions results in increased costs.

[0006] The present invention has been made in view of the above, and has an object to implement both rank detection and temperature detection functions while suppressing increases in cost. [Means for solving the problem]

[0007] The lighting device of the present invention comprises a light source unit having a light-emitting element, a rank detection element for identifying the rank of the light-emitting element, and a temperature detection element; a drive unit that supplies a drive current to the light-emitting element; and a control unit that detects the rank of the light-emitting element from the rank detection element and detects the temperature around the light-emitting element from the temperature detection element, and adjusts the drive current in accordance with the detection results of the rank and the temperature, wherein the light source unit has a switching circuit controlled in accordance with the drive current, and selectively connects the rank detection element and the temperature detection element to the control unit via the switching circuit. [Effects of the Invention]

[0008] According to the present invention, by selectively connecting the rank detection element and the temperature detection element to the control unit via a switching circuit controlled according to the drive current, it is possible to implement both rank detection and temperature detection functions while suppressing increases in cost. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a diagram showing a configuration of a vehicle lamp according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram showing the configuration of a vehicle lamp in which a switching circuit is specifically embodied. [Figure 3] 10 is a flowchart showing a process for adjusting a drive current supplied to a light-emitting element. [Figure 4] 10A and 10B are diagrams showing measurement values ​​of a rank detection signal and a temperature detection signal input to a control unit before and after driving a light-emitting element. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle lamp as an illumination device according to an embodiment of the present invention will now be described with reference to the accompanying drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals.

[0011] 1 is a diagram showing the configuration of a vehicle lamp 1. The vehicle lamp 1 includes a light source unit 2 and a lighting control device 3 that controls lighting of the light source unit 2.

[0012] The light source unit 2 is mounted on a light source board and includes a light emitting element 21, a rank detection element 22 for identifying the rank of the light emitting characteristics of the light emitting element 21, a temperature detection element 23 for detecting the temperature around the light emitting element 21, and a switching circuit composed of a switching circuit 24 for performing rank detection by the rank detection element 22 or temperature detection by the temperature detection element 23.

[0013] The lighting control device 3 is mounted on a control board separate from the light source board on which the light source unit 2 is mounted, and includes a drive unit 31 that supplies a drive current to the light-emitting element 21, and a control unit 32 that controls the drive unit 31.

[0014] The light-emitting element 21 is a light-emitting string made up of LEDs connected in series. The light-emitting element 21 is an LED. The number of light-emitting elements 21 may be one, or two or more, and can be set appropriately as needed. The light-emitting element 21 is not limited to an LED, and may be, for example, an organic EL (Electro Luminescence) element. The anode of the light-emitting element 21 is connected to a connector terminal 4a of a connector 4 provided on the light source board, and the cathode is connected to a connector terminal 4b of the connector 4. The connector terminals 4a and 4b are electrically connected to the drive unit 31 by connecting harnesses to connector terminals 5a and 5b of a connector 5 provided on the control board, respectively.

[0015] The rank detection element 22 is, for example, a rank resistor (BIN resistor), and light emission characteristics are ranked according to the resistance value of the rank resistor, and by reading the resistance value, it is possible to adjust the drive current according to the light emission characteristics of the light emitting element 21. Furthermore, the temperature detection element 23 is, for example, a thermistor, which is an element whose resistance value changes depending on the temperature, and by detecting the temperature, it is possible to adjust the drive current according to the temperature of the light emitting element 21.

[0016] One end of the rank detection element 22 is connected to a connector terminal 6a of a connector 6 provided on the light source board via a switching circuit 24 and a noise filter 25, and the other end is connected to a connector terminal 6b of the connector 6. Furthermore, one end of the temperature detection element 23 is connected to the connector terminal 6a via a switching circuit 24 and a noise filter 25, and the other end is connected to the connector terminal 6b via the switching circuit 24. The noise filter 25 is a low-pass filter that removes noise components from the detection signal from the rank detection element 22 or the temperature detection element 23. The connector terminals 6a and 6b are electrically connected to a rank detection unit 321 and a temperature detection unit 322 in the control unit 32 by connecting harnesses to connector terminals 7a and 7b, respectively, of a connector 7 provided on the control board.

[0017] The switching circuit 24 switches between connecting one of the rank detection element 22 and the temperature detection element 23 to the rank detection unit 321 and the temperature detection unit 322 of the control unit 32 in accordance with the drive current of the light-emitting element 21. The drive current supplied from the drive unit 31 is used as a control signal for switching the switching circuit 24. When the control signal is not input to the switching circuit 24, i.e., when no drive current is input to the switching circuit 24, the switching circuit 24 switches between connecting the rank detection element 22 to the control unit 32. When the control signal is input to the switching circuit 24, i.e., when a drive current is input to the switching circuit 24, the switching circuit 24 switches between connecting the temperature detection element 23 to the control unit 32.

[0018] The drive unit 31 applies an input voltage Vin supplied from a battery to generate an output voltage Vout, which is supplied to the light emitting element 21 connected to connector terminals 4a and 4b provided on the light source board via a harness from connector terminals 5a and 5b provided on the control board. The drive unit 31 feeds back the voltage generated across both ends of a detection resistor (not shown) as a detection signal for detecting the drive current Iout supplied to the light emitting element 21, compares it with a reference voltage, and performs constant current control so as to achieve a target current value.

[0019] The control unit 32 includes a switching element therein, and controls the on / off of the light-emitting element 21 by turning the switching element on / off, and also performs rank adjustment to adjust the drive current based on the rank of the light-emitting element 21, and temperature adjustment to adjust the drive current based on the temperature of the light-emitting element 21. The control unit 32 is configured by, for example, a microcomputer.

[0020] The control unit 32 includes a rank detection unit 321 that detects the rank of the light emitting element 21 from the rank detection element 22, and a temperature detection unit 322 that detects the temperature of the light emitting element 21 from the temperature detection element .

[0021] A reference voltage Vref, which is obtained by voltage conversion of an input voltage Vin from a battery (not shown), is connected to the control unit 32 via a resistor 33. The reference voltage Vref is also connected to a connector terminal 7a of a connector 7 provided on the control board via the resistor 33 and a noise filter 34. The connector terminal 7a is connected to a connector terminal 6a of the light source board via a harness, and the connector terminal 7b of the connector 7, which is connected to ground GND, is connected to the connector terminal 6b of the light source board via a harness. Therefore, the reference voltage Vref is applied to the rank detection element 22 and the temperature detection element 23 via the connector terminals 7a, 6a, 6b, and 7b. In this way, the connector terminals used for rank detection and the connector terminals used for temperature detection are the same. The signal detected by the rank detection element 22 and the signal detected by the temperature detection element 23 are input to a rank detection unit 321 and a temperature detection unit 322 in the control unit 32 via a common path via the connector terminals 6a, 6b, 7a, and 7b.

[0022] Next, Fig. 2 shows the configuration of a vehicle lamp 1 that embodies the switching circuit 24 shown in Fig. 1. The same parts as in Fig. 1 are given the same reference numerals, and a description thereof will be omitted. What differs from Fig. 1 is that the switching circuit includes a first switching element 241 and a second switching element 242, which are connected to the rank detection element 22 and the temperature detection element 23, respectively, and resistors 243, 244, and 245 are provided on a line to which the drive current for the light emitting element 21 is input as a control signal, and these are input to the bases of the switching element 241 and the switching element 242, respectively.

[0023] One end of the rank detection element 22 is connected to a connector terminal 6a provided on the light source board via a switching element 241 and a noise filter 25, and the other end is connected to a connector terminal 6b. Furthermore, one end of the temperature detection element 23 is connected to the connector terminal 6a via the noise filter 25, and the other end is connected to the connector terminal 6b via a switching element 242. The switching elements 241 and 242 constitute a switching circuit 24, and by turning the switching elements 241 and 242 on and off, the rank detection element 22 and the temperature detection element 23 are switched to be alternatively connected to the rank detection unit 321 and the temperature detection unit 322 of the control unit 32.

[0024] The switching element 241 is a PNP transistor, and its collector is connected to the rank detection element 22, and its emitter is connected to the connector terminal 6a via the noise filter 25. The base of the switching element 241 is connected between the resistors 243 and 244 in a path that connects the connector terminal 4a to the connector terminal 6b via the resistors 243, 244, and 245, and the driving current supplied from the driving unit 31 is input to the base of the switching element 241.

[0025] The switching element 242 is an NPN transistor, and its collector is connected to the temperature detection element 23 and its emitter is connected to the connector terminal 6b. The base of the switching element 242 is connected between the resistors 244 and 245 in a path that connects the connector terminal 4a to the connector terminal 6b via the resistors 243, 244, and 245. Similar to the switching element 241, the base of the switching element 242 receives the drive current supplied from the drive unit 31.

[0026] Therefore, the on / off of switching element 241 is controlled according to the drive current from drive unit 31 supplied to the base of switching element 241 and the base of switching element 242, while the on / off of switching element 242 is controlled in the opposite manner to switching element 241, and either rank detection element 22 or temperature detection element 23 is electrically connected to control unit 32.

[0027] Next, the rank adjustment and temperature adjustment operations performed by the control unit 32 will be described with reference to a flowchart.

[0028] 3 is a flowchart of the adjustment process showing the rank adjustment and temperature adjustment operations. First, in step S101, the control unit 32 determines whether or not the drive unit 31 has not yet started supplying the drive current Iout.

[0029] Here, the light source unit 2 is configured such that a driving current Iout is input to the bases of switching elements 241 and 242 that switch between connecting to either the rank detection element 22 or the temperature detection element 23. The switching element 241 is in an on state when no driving current Iout is input to its base, and the switching element 242 is in an off state when no driving current Iout is input to its base. Therefore, when no driving current Iout is supplied to the bases of the switching elements 241 and 242, only the rank detection element 22 is in a detectable state.

[0030] If the control unit 32 determines that the drive unit 31 has not yet started supplying the drive current Iout (step S101: Yes), it executes rank detection by the rank detection unit 321 (step S102). If it does not determine that the drive unit 31 has not yet started supplying the drive current Iout (step S101: No), the processing operation of step S101 is repeated.

[0031] Here, the rank detection unit 321 is connected between the resistor 33 and the rank detection element 22. Therefore, the rank detection unit 321 receives a voltage obtained by dividing the reference voltage Vref between the resistor 33 and the rank detection element 22, i.e., a voltage appearing across the rank detection element 22. The rank detection unit 321 measures the input voltage and calculates the resistance value of the rank detection element 22. The control unit 32 is provided with a memory unit 323, which stores a correspondence table indicating the resistance value of the rank detection element 22 corresponding to each rank of the light-emitting element 21. The rank detection unit 321 identifies the rank of the light-emitting element 21 from the calculated resistance value by referring to the correspondence table stored in the memory unit 323. Note that the correspondence table may associate measured voltages with each rank instead of the resistance value of the rank detection element 22. The correspondence table also stores an adjustment value for generating an adjustment current. The control unit 32 reads the adjustment value corresponding to the rank from the memory unit 323 and sets it in the drive unit 31 (step S103). The measured voltage, resistance value, rank, or adjustment value detected by the rank detection unit 321 is stored in the storage unit 323.

[0032] When the rank adjustment is completed, the control unit 32 determines whether the drive unit 31 has started supplying the drive current Iout (step S104). If the control unit 32 determines that the drive current Iout has started supplying the drive current Iout (step S104: Yes), the control unit 32 executes temperature detection by the temperature detection unit 322 (step S105). If the control unit 32 does not determine that the drive unit 31 has started supplying the drive current Iout (step S104: No), the processing operation of step S104 is repeated.

[0033] When the supply operation of the drive current Iout starts, the drive current Iout is input to the bases of the switching elements 241 and 242. The switching element 241 is in the OFF state when the drive current Iout is input to its base, and the switching element 242 is in the ON state when the drive current Iout is input to its base. Therefore, when the drive current Iout is supplied to the bases of the switching elements 241 and 242, only the temperature detection element 23 is in the detectable state.

[0034] The temperature detection unit 322 is connected between the resistor 33 and the temperature detection element 23. Therefore, the temperature detection unit 322 receives a voltage obtained by dividing the reference voltage Vref between the resistor 33 and the temperature detection element 23, i.e., the voltage appearing across the temperature detection element 23. The temperature detection unit 322 measures the input voltage and calculates the temperature of the temperature detection element 23. The memory unit 323 in the control unit 32 stores an adjustment value for generating an adjustment current corresponding to the temperature of the light-emitting element 21. The control unit 32 reads the adjustment value corresponding to the temperature from the memory unit 323 and sets it in the drive unit 31 (step S106). Note that the memory unit 323 may store an adjustment value for generating an adjustment current corresponding to the measured voltage, rather than the ambient temperature of the light-emitting element 21.

[0035] The control unit 32 includes an adjustment current generator that generates an adjustment current according to the adjustment value of the rank adjustment and the adjustment value of the temperature adjustment. The adjustment current generated by the adjustment current generator is configured to be supplied to the connector terminal 5b side where a detection resistor (not shown) is provided, so that a drive current to which the adjustment current that has been adjusted for rank and temperature is applied is supplied to the light-emitting element 21. Alternatively, the control unit 32 may include an adjustment voltage generator that generates an adjustment voltage according to the adjustment value of the rank adjustment and the adjustment value of the temperature adjustment, instead of the adjustment current generator. The adjustment voltage generated by the adjustment voltage generator is configured to be applied to the drive unit 31 in addition to the input voltage Vin, so that the output voltage is adjusted, and a drive current to which the adjustment current that has been adjusted for rank and temperature is applied is supplied to the light-emitting element 21.

[0036] When the temperature adjustment value is set in step S106, the control unit 32 determines whether the operation of supplying the drive current Iout by the drive unit 31 has ended (step S107). If the control unit 32 determines that the operation of supplying the drive current Iout has not ended (step S107: No), the process returns to step S105, where the temperature detection unit 322 continues to detect the temperature and the temperature adjustment value is set in step S106. If the control unit 32 determines that the operation of supplying the drive current Iout by the drive unit 31 has ended (step S107: Yes), the adjustment process ends. As described above, the adjustment of the drive current of the light-emitting element 21 based on rank detection is performed before the light-emitting element 21 is driven, and while the adjustment value is maintained, the adjustment of the drive current of the light-emitting element 21 based on temperature detection is performed while the light-emitting element 21 is being driven, and continues until the driving ends.

[0037] FIG. 4 shows measured values ​​of the rank detection and temperature detection signals input to the control unit 32 before and after driving the light emitting element 21 in the vehicle lamp 1 of this embodiment. In the figure, the vertical axis represents voltage and the horizontal axis represents time. On the horizontal axis, 0 to 100 ms represents before driving the light emitting element 21, and 100 ms marks the boundary at which the light emitting element 21 is driven. Here, the measured values ​​are shown when three rank resistors with resistance values ​​of 510 Ω, 1.0 kΩ, and 1.5 kΩ are used as the rank detection element 22. Also, the measured values ​​are shown when a thermistor is used as the temperature detection element and the thermistor temperatures are 75°C, 100°C, and 125°C.

[0038] Before the light-emitting element 21 is driven, the bases of the switching elements 241 and 242 are not supplied with the drive current for the light-emitting element 21 and are grounded, with the switching element 241 in an ON state and the switching element 242 in an OFF state. Therefore, when no drive current is supplied to the bases of the switching elements 241 and 242, only the rank detection element 22 is in a detectable state. In the period 0 to 100 ms before the light-emitting element 21 is driven, if the resistance value of the rank detection element 22 is 510Ω, a voltage value of 1.0V corresponding to this resistance value is detected. Furthermore, if the resistance value of the rank detection element 22 is 1.0 kΩ, a voltage value of 1.5V corresponding to this resistance value is detected, and if the resistance value is 1.5 kΩ, a voltage value of 1.95V corresponding to this resistance value is detected.

[0039] Next, at 100 ms, when light-emitting element 21 is driven, the drive current for light-emitting element 21 is input to the bases of switching elements 241 and 242, switching element 241 changes to the OFF state, and switching element 242 changes to the ON state. Therefore, when the drive current is supplied to the bases of switching elements 241 and 242, only temperature detection element 23 is set to a detectable state. 100 ms after light-emitting element 21 is driven, if the temperature of temperature detection element 23 is 75°C, a voltage of 2.5V corresponding to this temperature is detected. Furthermore, if the temperature of temperature detection element 23 is 100°C, a voltage of 1.7V corresponding to this temperature is detected, and if the temperature is 125°C, a voltage of 1.05V corresponding to this temperature is detected.

[0040] In this way, it is possible to switch between rank detection and temperature detection before and after driving by switching the connection depending on the presence or absence of drive current for the light emitting element 21. Therefore, it is possible to share the path between the rank detection element 22 and the rank detection unit 321 and the path between the temperature detection element 23 and the temperature detection unit 322, and it is possible to suppress an increase in the number of connector terminals for forming the paths and the noise filters and harnesses based thereon, thereby suppressing an increase in costs.

[0041] In the above embodiment, a transistor is used as an example of a switching element, but the switching element is not limited to this and may be a FET (Field Effect Transistor).

[0042] In the above embodiment, the drive unit 31 is not limited to a linear regulator, but may be a switching regulator. The control unit 32 may be a CPU (Central Processing Unit) using an AD converter. Software processing allows the rank detection unit, temperature detection unit, and storage unit to share hardware.

[0043] Furthermore, in the above embodiment, the description has been given of a vehicle lamp, but the invention is not limited to this and the lighting device can also be used for other purposes such as amusement equipment.

[0044] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0045] 1...vehicle lamp, 2...light source unit, 3...lighting control device, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b...connector terminal, 21...light emitting element, 22...rank detection element, 23...temperature detection element, 24...switching circuit, 25, 34...noise filter, 33, 243, 244, 245...resistor, 31...drive unit, 32...control unit, 241, 242...switching element, 321...rank detection unit, 322...temperature detection unit, 323...storage unit

Claims

1. a light source unit including a light emitting element, a rank detection element for identifying the rank of the light emitting element, and a temperature detection element; a driving unit that supplies a driving current to the light-emitting element; a control unit that detects the rank of the light-emitting element from the rank detection element and detects the temperature around the light-emitting element from the temperature detection element, and adjusts the drive current according to the detection results of the rank and the temperature; Equipped with the light source unit includes a switching circuit controlled in response to the driving current, and the light source unit selectively connects the rank detection element and the temperature detection element to the control unit via the switching circuit. Lighting equipment.

2. the switching circuit connects the rank detection element to the control unit when the drive current is not supplied, and connects the temperature detection element to the control unit when the drive current is supplied. The lighting device according to claim 1 .

3. the switching circuit comprises a first switching element connected to the rank detection element and controlled in response to the drive current, and a second switching element connected to the temperature detection element and controlled in an opposite manner to the first switching element in response to the drive current; the light source unit selectively connects the rank detection element and the temperature detection element to the control unit via the first switching element and the second switching element. The lighting device according to claim 1 .

4. the first switching element is turned on when the drive current is not supplied, and turned off when the drive current is supplied; the second switching element is turned off when the drive current is not supplied, and turned on when the drive current is supplied; 4. The lighting device according to claim 3.

5. the control unit detects the rank when the light-emitting element is not driven, and detects the temperature when the light-emitting element is driven, based on a signal detected via the switching circuit.

5. The lighting device according to claim 2 or 4.

6. The control unit holds the detected rank.

6. The lighting device according to claim 5.

7. The light source unit is mounted on a light source substrate, the control unit is mounted on a control board separate from the light source board, the light source board includes a connector having a connector terminal that selectively connects the rank detection element and the temperature detection element via the switching circuit, the control unit is connected to the rank detection element or the temperature detection element via the connector; The lighting device according to claim 1 .

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