Light source control device

Abstract

Light source control device (1) comprising: a light source (211); a push button (213) whose one side is connected to a power source via a pull-up resistor (119), and whose other side is connected to ground, wherein when the push button (213) is actuated its one side is conductively connected to its other side, and when the push button (213) is not actuated the connection between the one side and the other side is interrupted; a control unit (110) which is connected to one side of the push button (213) and which has an input terminal (106) to which a switching signal is applied corresponding to the actuation state of the push button (213), wherein the control unit (110) controls the current supply to the light source (211) such that the light source (211) is switched between an illuminated state and a non-illuminated state when, based on the switching signal, it is detected that the push button (213) has been actuated; a temperature-sensitive resistor (214), one side of which is connected to one side of the button (213), and the other side of which is connected to ground, and whose resistance changes depending on the temperature; and a switching means (20) which is provided between the other side of the temperature-sensitive resistor (214) and ground, and which switches between a state in which current flows through the temperature-sensitive resistor (214) and a state in which no current flows through the temperature-sensitive resistor (214), wherein a switching signal from the push button (213) or a voltage divider signal is received at the input terminal (106) of the control unit (110) by dividing the voltage of the current source by the pull-up resistor (119) and the temperature-sensitive resistor (214); and The control unit (110) controls the luminance of the light source (211) based on the voltage divider signal.

Description

TECHNICAL AREA

[0001] The present invention relates to a light source control device. TECHNICAL BACKGROUND

[0002] The use of LEDs as light sources for vehicle lights is becoming increasingly widespread. However, there is a possibility that the LEDs themselves, or components installed near them, may degrade due to the heat generated by the LEDs. To prevent this, a device has been proposed in the prior art that is equipped with a temperature-sensitive resistor which detects the temperature near the LEDs and, based on this temperature, reduces the current supplied to the LEDs, thus suppressing their heat generation. STATE OF TECHNOLOGY PATENT DOCUMENTS

[0003] JP 2014-154335 A discloses a lighting device comprising an ignition / control circuit that supplies electrical power to a light source consisting of a light-emitting element, a first detection unit provided on the light source and comprising a first impedance element whose impedance changes continuously depending on the temperature of the light source, a second detection unit comprising a second impedance element whose impedance switches to one of two binary values ​​depending on the state of an object to be detected, which changes between a first state and a second state, a pair of terminals to which the first detection unit and the second detection unit are connected, and a control circuit that controls the control circuit based on the impedance between the terminals, which consists of the total impedance of the first impedance element and the second impedance element.or is controlled based on a voltage value between the terminals, wherein the impedance between the terminals and the voltage value between the terminals change continuously when the first state of the object to be detected is within a predetermined range and change outside the predetermined range when the second state of the object to be detected is present, and wherein the control circuit increases or decreases the output power of the drive circuit based on the impedance or voltage value between the terminals when the impedance or voltage value between the terminals is within the predetermined range, and detects that the impedance or voltage value between the terminals is outside the predetermined range or exhibits a discontinuous change.that the object to be detected is in the second state.

[0004] EP 2 048 916 A1 discloses a lighting network with several lighting units as network nodes, which are connected to a common power supply unit in which a channel for information transmission is also formed, wherein each lighting unit is provided with or directly coupled to one or more operating and / or sensor elements and has an information signal line with one or more wires, and the information signal line is coupled to the operating and / or sensor element(s) as well as to the information transmission channel. Outline of the invention; Problem to be solved by the invention

[0005] However, it is also common practice to use LEDs as a light source for vehicle interior lighting, just as it is for vehicle headlights, and there is a need to increase the luminance of the LEDs to make the interior brighter. When the luminance of the LEDs is increased, the amount of heat emitted by the LEDs also increases, so, as with vehicle headlights, it is necessary to include a temperature-sensitive resistor to monitor the temperature near the LEDs. Furthermore, a vehicle interior lighting device located in the front area of ​​the ceiling is equipped with a control unit, and a vehicle interior lighting device in the middle of the ceiling, which is spaced away from the front area, is controlled by the control unit in the front area of ​​the ceiling.In this case, the control unit and the LEDs of the vehicle's interior lighting system are located on separate circuit boards in the center of the ceiling. Furthermore, the circuit board for the interior lighting system in the center of the ceiling, which also houses the LEDs and the temperature-sensitive resistor, includes a push button. Pressing this button switches the LEDs on and off. This increases the number of connectors required, and a wiring harness is also necessary to connect the circuit board in the front of the ceiling, where the control unit is located, to the circuit board in the center of the ceiling, where the LEDs of the interior lighting system are located, thus increasing the overall cost.

[0006] The present invention was made against the background described above and provides a light source control device which can reduce costs even when it includes a temperature-sensitive resistor and a push button. MEANS TO SOLVE THE PROBLEM

[0007] A light source control device according to a first embodiment of the invention comprises the features of claim 1.

[0008] The light source control device according to the first embodiment comprises a light source, a push button, a control unit, and a temperature-sensitive resistor. The control unit detects the actuation of the push button at its input terminal, and when the button is not actuated, it detects a voltage divider signal, obtained by dividing the voltage of the power source with the pull-up resistor and the temperature-sensitive resistor. Based on the result of the detection at the input terminal, the control unit switches the light source on or off when the push button is actuated and also controls the luminance of the light source using the voltage divider signal. Consequently, with this arrangement, the actuation of the push button and the temperature near the light source can be detected with only a single input terminal of the control unit, thus reducing the cost of the light source control device.

[0009] A light source control device according to a second embodiment of the invention comprises the features of claim 2.

[0010] The light source control device according to the second embodiment comprises a light source, a push button, a control unit, a temperature-sensitive resistor, a first circuit board, and a second circuit board. The first and second circuit boards are spaced apart from each other, with the control unit located on the first circuit board and the light source, push button, and temperature-sensitive resistor located on the second circuit board. The actuation of the push button is detected at the input terminal of the control unit, and when the push button is not actuated, a voltage divider signal is detected. This signal is obtained by dividing the voltage of the power source by the pull-up resistor and the temperature-sensitive resistor. Based on the result of the detection at the input terminal, the control unit switches the light source on or off when the push button is actuated and also controls the luminance of the light source based on the voltage divider signal.Consequently, with this arrangement, the actuation of the button and the temperature near the light source can be detected with only a single input connection of the control unit, thus reducing the number of cable strands and therefore the cost of the light source control device.

[0011] A light source control device according to a third embodiment of the invention is a light source control device according to the first or second embodiment and further comprises a switching means which is provided between the other side of the temperature-sensitive resistor and ground, and which switches between a state in which current flows through the temperature-sensitive resistor and a state in which no current flows through the temperature-sensitive resistor.

[0012] The light source control device according to the third embodiment is a light source control device according to the first or second embodiment and further comprises a switching means. The switching means, which switches the current flowing through the temperature-sensitive resistor, performs a control function that ensures no current flows through the temperature-sensitive resistor when it is not necessary to detect the temperature with the temperature-sensitive resistor. Consequently, this arrangement makes it possible to prevent an increase in the current consumption of the light source control device.

[0013] A light source control device according to a fourth embodiment is a light source control device according to the third embodiment, and further comprises a current supply means for supplying current to the switching means, coupled to the supply of current to the light source.

[0014] The light source control device according to the fourth embodiment is a light source control device according to the third embodiment and further comprises a current supply means that is coupled to the current supply to the light source. Current is supplied from the current supply means to the switching means, and the switching means is controlled. Since the current supply means is provided that supplies current to the switching means in response to the state of the current supply to the light source, the switching means, in response to the state of the current supply to the light source, switches to a state in which no current flows through the temperature-sensitive resistor when, in the off state of the light source, it is not necessary to allow a current to flow through the temperature-sensitive resistor to detect the temperature.Therefore, in this arrangement it is not necessary to provide a control connection in the control unit to control the switching device, and an increase in the power consumed can be prevented without increasing costs. EFFECTS OF INVENTION

[0015] With the embodiments according to the invention, a light source control device can be provided which can reduce costs, even if it has a temperature-sensitive resistor and a push button. BRIEF EXPLANATION OF THE FIGURES Fig. Figure 1 is a diagram showing the structure of a light source control device 1 according to a first embodiment of the invention. Fig. Figure 2 is a circuit diagram of the light source control device 1 according to the first embodiment according to the invention. Fig. Figure 3 is a diagram showing the relationship between the actuation of the button of the light source control device 1 according to the first embodiment according to the invention and the input voltage that is entered into the control unit. Fig. Figure 4 is a diagram showing the relationship between the temperature of the light source control device 1 according to the first embodiment of the invention and the input voltage that is entered into the control unit. Fig. Figure 5 is a diagram showing the relationship between the temperature of the light source control device 1 according to the first embodiment of the invention and the PWM duty cycle. EXAMPLE OF EXECUTION First example of execution

[0016] With reference to the Fig. 1 and Fig. 2 In the following, a light source control device 1 according to a first embodiment according to the invention is explained. Structure of the light source control device 1

[0017] Fig. Figure 1 is a diagram showing the structure of a light source control device 1 according to this embodiment, which is installed in a vehicle V. The vehicle V in which the light source control device 1 is installed can be, for example, a four-wheeled vehicle, which includes vehicles with an internal combustion engine such as a diesel engine or a gasoline engine as a drive source, as well as electric vehicles with an electric motor as a drive source and hybrid vehicles with an internal combustion engine and an electric motor.

[0018] The light source control device 1 comprises a control unit board 100 and an LED board 200. The control unit board 100 and the LED board 200 are connected to each other by a cable harness 150.

[0019] The control unit board 100 is located in the front area of ​​the vehicle interior ceiling of vehicle V, and the LED board 200 is located in the middle area of ​​the vehicle interior ceiling. A control unit for controlling the vehicle interior lighting is integrated into the control unit board 100, and one or more LEDs for illuminating the vehicle interior at night or similar purposes, as well as an operating switch, are integrated into the LED board 200.

[0020] It is also possible that the control unit board 100, like the LED board 200, is equipped with a circuit arrangement for illuminating the vehicle interior. For the sake of simplicity, this possibility is not explained in detail in the present embodiment. Control unit board layout 100

[0021] The control unit board 100 includes a control unit 110, an LED power source circuit 10, a PWM control circuit 11, a detection circuit 12, and connection terminals 101 - 103.

[0022] The control unit 110 has connections 104 - 106.

[0023] The LED current source circuit 10 includes transistors 111 and 112 as well as resistors 113 - 115.

[0024] The emitter of transistor 111 is connected to one end of resistor 113 and to a power source for operating the LED lighting. It is connected to the positive terminal of a battery installed in vehicle V, but can also be connected to the output of a stabilizing current source circuit, which is supplied with voltage from the battery installed in vehicle V. The base of transistor 111 is connected to the other end of resistor 113 and to the collector of transistor 112. The collector of transistor 111 is connected to terminal 101. The emitter of transistor 112 is connected to ground. The base of transistor 112 is connected to one end of resistor 114 and to one end of resistor 115. The other end of resistor 114 is connected to terminal 104, and the other end of resistor 115 is connected to ground.

[0025] The PWM control circuit 11 comprises a transistor 116, a resistor 117, and a resistor 118. The collector of transistor 116 is connected to terminal 102, its emitter is connected to ground, and its base is connected to one side of resistor 117 and one side of resistor 118. The other side of resistor 117 is connected to terminal 105, and the other side of resistor 118 is connected to ground.

[0026] The detection circuit 12 includes a resistor 119, which is configured as a pull-up resistor. One side of the resistor 119 is connected to terminal 106 and the connecting terminal 103. The other side of the resistor 119 is connected in a pull-up configuration to the output of the stabilizing current source circuit, which is supplied with voltage V from the vehicle's battery (not shown in detail). In the present embodiment, this voltage can be, for example, 5 V, and the same voltage can also be supplied to the control unit 110. LED board structure 200

[0027] The LED board 200 includes one or more LEDs 211 as a light source, a resistor 210, a push button 213, a temperature-sensitive resistor 214, a switching circuit 20 and connection terminals 201 - 203.

[0028] The connection terminal 201 is connected to one side of the resistor 210.

[0029] Furthermore, the connection terminal 201 is connected to one side of a resistor 216 via a power supply line 218, which serves as a power supply means.

[0030] The anode of LED 211 is connected to the other side of resistor 210, and its cathode is connected to the connection terminal 202.

[0031] The connection terminal 203 is connected to one side of the push button 213 and to one side of the temperature-sensitive resistor 214. The other side of the push button 213 is connected to ground, and the other side of the temperature-sensitive resistor 214 is connected to the collector of a transistor 215.

[0032] The switching circuit 20, which serves as a switching device, comprises the transistor 215, the resistor 216 and a resistor 217.

[0033] The emitter of transistor 215 is connected to ground, and its base is connected to the other end of resistor 216 and to one end of resistor 217. The other end of resistor 217 is connected to ground.

[0034] The connection terminals 201 - 203 are connected via the cable harness 150 respectively to the connection terminals 101 - 103 of the control unit board 100. Operation of the light source control device 1

[0035] The control unit 110, for example, is designed as a microcontroller and includes input and output connections. Connection 106, which serves as the input connection of the control unit 110, is an analog input. A voltage applied to this connection is converted from analog to digital, and the applied voltage value is fed into the control unit 110 (not shown in detail). A switching signal corresponding to the operating state of the push button 213, which is provided on the LED board 200, is input into connection 106.

[0036] Fig. Figure 3 shows the voltage applied to terminal 106 when push button 213 is in the ON state and the OFF state, respectively. When push button 213 is pressed, it assumes the ON state, shorting terminal 106 to ground. When push button 213 is not pressed, it assumes the OFF state, applying a voltage of 5 V to terminal 106. Furthermore, when the LED current source circuit 10, described later, is in the ON state, a voltage obtained by dividing the 5 V by the temperature-sensitive resistor 214 and resistor 119 is applied. Therefore, in Fig. Figure 3 shows that a voltage of approximately 5 V is applied to terminal 106 when the button 213 is in the OFF state, however, the level of this voltage changes with the temperature.

[0037] Fig. Figure 4 shows the temperature near the temperature-sensitive resistor 214 and the value of the voltage applied to terminal 106. In the present embodiment, the temperature-sensitive resistor 214 is designed using a thermistor. A thermistor with a negative temperature characteristic is used as the temperature-sensitive resistor 214; its resistance decreases as the temperature rises. Consequently, the value of the voltage applied to terminal 106 decreases as the temperature rises. The control unit 110 can detect the temperature near the LED 211 from the voltage applied to terminal 106. For the temperature to be detected, the LED current source circuit 10, described later, must be in the ON state.

[0038] The LED current source circuit 10 is switched on and off by the signal output from terminal 104 of the control unit 110. When the control unit 110 detects that the push button 213 has been pressed, via the signal present at its terminal 106, it outputs a high-level control signal from terminal 104, thus switching on the LED current source circuit 10. When the LED current source circuit 10 is switched on (i.e., put into the ON state), a voltage is supplied to terminal 201 of the LED board 200 via terminal 101 and cable 150. The voltage supplied to terminal 201 is fed to the switching circuit 20 via power supply line 218, and transistor 215 is switched on.

[0039] The PWM control circuit 11 controls the current flowing through the LED 211 by outputting a PWM control signal from terminal 105 of the control unit 110. The current flowing through the LED 211 changes with the duty cycle of the PWM control signal, depending on the temperature reading near the LED 211 as described above. When the PWM control circuit 11 is switched on with the PWM control signal at terminal 105, current flows through resistor 210 and the LED 211, and the LED illuminates.

[0040] Fig. Figure 5 shows the duty cycle of the PWM control signal as a function of the temperature near LED 211 in the present embodiment. If the temperature, calculated from the voltage applied to terminal 106, is no more than 85°C, a PWM control signal with a 100% duty cycle is output at terminal 105. If the temperature exceeds 85°C, a PWM control signal with a 50% duty cycle is output, and if the temperature exceeds 90°C, a PWM control signal with a 5% duty cycle is output. This control is applied as the temperature rises, but as the temperature falls, the duty cycle is changed with hysteresis. If the temperature drops below 85°C, the duty cycle is changed from 5% to 50%, and if the temperature drops below 80°C, the duty cycle is changed from 50% to 100%.The control unit 110 monitors the temperature near the LED 211 and controls the duty cycle of the PWM control circuit 11 according to the temperature, thus regulating the luminance (and therefore the amount of radiated heat) of the LED 211. Operational effect

[0041] As in Fig. As shown in Figure 2, the light source control device 1 of the present embodiment comprises a control unit board 100, an LED board 200 and a cable harness 150.

[0042] The control unit board 100 includes a control unit 110, an LED power source circuit 10, a PWM control circuit 11 and a detection circuit 12.

[0043] The LED board 200 includes an LED 211, a push button 213 and a temperature-sensitive resistor 214.

[0044] When the button 213 is pressed, the LED 211 is switched on or off by the control unit 110 of the light source control device 1 arranged in this way, and the luminance of the LED 211 is further regulated depending on the result of the temperature measurement by the PWM control circuit 11. Since both the sensing of the actuation of the button 213 and the temperature measurement with the temperature-sensitive resistor 214 are carried out with only a single connection 106, the number of connections used in the control unit can be reduced, and the costs can be lowered.

[0045] Even if the LED board 200, on which the LED 211, the push button 213, and the temperature-sensitive resistor 214 are mounted and which serves as the second board, is located in a different position and at a distance from the control unit board 100, which serves as the first board, it is possible to detect the actuation of the push button 213 and the temperature using the temperature-sensitive resistor 214 with only a single connection 106, thus simplifying the number of cable strands 150 and reducing costs. Furthermore, the number of connections in the cable strand can be reduced, thereby decreasing the number of wires in the cable strand and also reducing the weight of the light source control device 1.

[0046] Furthermore, a switching circuit 20 is integrated into the LED board 200. The switching circuit 20, which switches the current flowing through the temperature-sensitive resistor 214, performs a control function that ensures no current flows through the temperature-sensitive resistor 214 when it is not necessary to detect the temperature using the temperature-sensitive resistor 214. Consequently, this arrangement makes it possible to reduce the power consumption of the light source control device 1. And because the switching circuit 20 controls the voltage supplied by the LED power source circuit 10 via the power supply line 218, it is not necessary to provide a control terminal on the control unit 110, thus reducing costs.Furthermore, the number of connections in the cable harness can be reduced, thus reducing the number of wires in the cable harness and also reducing the weight of the light source control device 1. Further embodiments

[0047] The present invention is not limited to the embodiment described above, but can be varied in various ways within the scope of the claims.

[0048] An example was described above in which the inventive switching on and off of the LED power source circuit 10 is done by pressing a button 213, however this can also be done by switching on and off the accessory power source in the vehicle V. REFERENCE MARK LIST 1 Light source control device 10 LED power source circuit 11 PWM control circuit 12 Detection circuit 150 cable harness 100 control unit boards 101, 102, 103, 201, 202, 203 Connection ports 104, 105, 106 connections 110 Control unit 20 switching circuit 200 LED board 211 LED 213 buttons 214 temperature-sensitive resistor 218 Power supply line V vehicle

Claims

[1] Light source control device (1) comprising: a light source (211); a push button (213) whose one side is connected to a power source via a pull-up resistor (119), and whose other side is connected to ground, wherein when the push button (213) is actuated its one side is conductively connected to its other side, and when the push button (213) is not actuated the connection between the one side and the other side is interrupted; a control unit (110) which is connected to one side of the push button (213) and which has an input terminal (106) to which a switching signal is applied corresponding to the actuation state of the push button (213), wherein the control unit (110) controls the current supply to the light source (211) such that the light source (211) is switched between an illuminated state and a non-illuminated state when, based on the switching signal, it is detected that the push button (213) has been actuated; a temperature-sensitive resistor (214), one side of which is connected to one side of the button (213), and the other side of which is connected to ground, and whose resistance changes depending on the temperature; and a switching means (20) which is provided between the other side of the temperature-sensitive resistor (214) and ground, and which switches between a state in which current flows through the temperature-sensitive resistor (214) and a state in which no current flows through the temperature-sensitive resistor (214), wherein a switching signal from the push button (213) or a voltage divider signal is received at the input terminal (106) of the control unit (110) by dividing the voltage of the current source by the pull-up resistor (119) and the temperature-sensitive resistor (214); and The control unit (110) controls the luminance of the light source (211) based on the voltage divider signal. [2] Light source control device (1) comprising: a light source (211); a push button (213) whose one side is connected to a power source via a pull-up resistor (119), and whose other side is connected to ground, wherein when the push button (213) is actuated its one side is conductively connected to its other side, and when the push button (213) is not actuated the connection between the one side and the other side is interrupted; a control unit (110) which is connected to one side of the push button (213) and which has an input terminal (106) to which a switching signal is applied corresponding to the actuation state of the push button (213), wherein the control unit (110) controls the current supply to the light source (211) such that the light source (211) is switched between an illuminated state and a non-illuminated state when, based on the switching signal, it is detected that the push button (213) has been actuated; a temperature-sensitive resistor (214), one side of which is connected to one side of the button (213), and the other side of which is connected to ground, and whose resistance changes depending on the temperature; and a switching means (20) which is provided between the other side of the temperature-sensitive resistor (214) and ground, and which switches between a state in which current flows through the temperature-sensitive resistor (214) and a state in which no current flows through the temperature-sensitive resistor (214), wherein the light source control device (1) is provided with a first circuit board (100) and a second circuit board (200) which are spaced apart from each other; the control unit (110) is provided on the first circuit board (100); the light source (211), the push button (213) and the temperature-sensitive resistor (214) are provided on the second circuit board (200); a switching signal from the push button (213) or a voltage divider signal is received at the input terminal (106) of the control unit (110) by dividing the voltage of the current source by the pull-up resistor (119) and the temperature-sensitive resistor (214); and The control unit (110) controls the luminance of the light source (211) based on the voltage divider signal. [3] Light source control device (1) according to claim 1 or 2, further comprising a current supply means (218) for supplying current to the switching means (20), coupled to the supply of current to the light source (211).

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