JP2006172819A - Lighting control circuit of vehicular lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a switching regulator and an LED by rapidly detecting its abnormality when the LED has been opened. <P>SOLUTION: In a process in which switches SW 1-SW 5 are ON/OFF operated by switching signals from a microcomputer 44, and in which lighting of LED 1-LED 5 is controlled by discharging electromagnetic energy accumulated in switching regulators 12-20 to output blocks 22-30, for example, when the LED 1 becomes opened, and an abnormality detecting signal is inputted from an open detection circuit 32 to the external interruption terminal 66 and a signal input terminal 68, the microcomputer 44 determines that the LED 1 has become open from the abnormality detecting signal, and as the external interruption processing to respond to the abnormality detecting signal, only on-duty of the switching signals to the switch SW 1 is made smaller, and the output voltage of the switching regulator 12 is prevented from becoming overvoltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting control circuit for a vehicular lamp, and more particularly, to a lighting control circuit for a vehicular lamp configured to control lighting of a semiconductor light source composed of a semiconductor light emitting element.

  2. Description of the Related Art Conventionally, a vehicular lamp using a semiconductor light emitting element such as an LED (Light Emitting Diode) as a light source is known, and this type of vehicular lamp has a lighting control circuit for controlling the lighting of the LED. Has been implemented.

  When configuring the lighting control circuit, a switching regulator equipped with a switching element and a transformer is used. The input voltage from the DC power supply is stored in the transformer as electromagnetic energy when the switching element is turned on, and the electromagnetic energy stored in the transformer is switched. There is one in which an element is supplied to an LED via a rectifier diode and a smoothing capacitor from the secondary side of the transformer when the element is turned off (see Patent Document 1). In this lighting control circuit, a configuration is adopted in which the operation of the switching regulator is stopped when the disconnection of the LED is detected.

  On the other hand, when controlling the on / off operation of the switching element of the switching regulator, it has been attempted to generate a switching signal using a microcomputer and control the on / off operation of the switching element in accordance with the switching signal. When the switching element of the switching regulator is controlled using the microcomputer and the state of the LED is monitored, the voltage applied to the LED is divided and taken into the microcomputer, and the taken-in voltage is stored in the A built in the microcomputer. A digital data is converted using a / D converter, and it is determined whether or not an LED is disconnected (opened) based on the converted digital data. If processing for determining whether or not an LED is disconnected using a microcomputer is performed, processing for a plurality of switching regulators can be performed by a single microcomputer.

JP 2004-134147 A (pages 2 to 6, FIGS. 1 and 2)

  In the method of processing the digital data obtained by the A / D converter in the microcomputer when monitoring the state of the LED using the microcomputer, the A / D conversion usually requires several tens of microseconds, and the LED Cannot be detected quickly. In particular, when monitoring the state of a plurality of LEDs, the voltage obtained from each LED must be A / D converted by an A / D converter, which requires a lot of time for A / D conversion. Become. In addition, processing time is also required for channel switching for sequentially taking in data from each A / D converter, and even if one of the plurality of LEDs is disconnected, it is disconnected once every several hundreds of μs. Will be detected. In other words, even if one LED is disconnected, control is performed to limit the output of the switching regulator several hundreds of μs after disconnection, and it takes time to stop the operation of the switching regulator even if the LED is disconnected. Therefore, when the LED is disconnected, the output voltage of the switching regulator cannot be sufficiently suppressed, the output of the switching regulator becomes an overvoltage, and the LED and the circuit elements of the switching regulator may be destroyed.

  The present invention has been made in view of the above-described problems of the prior art, and its purpose is to quickly detect an abnormality when a semiconductor light source connected to the switching regulator has an abnormality to detect the switching regulator or It is to protect circuit elements and semiconductor light sources connected to the switching regulator.

  In order to achieve the above object, in the lighting control circuit for a vehicle lamp according to claim 1, the input voltage from the power source is converted into electromagnetic energy by the on / off operation of the switching element connected to the transformer or the coil. A switching regulator that emits, energy propagation means that rectifies electromagnetic energy emitted from the switching regulator and propagates it as light emission energy to one or a plurality of different semiconductor light sources, and a switching signal for turning on and off the switching element A microcomputer for controlling the on / off operation of the switching element based on the result of the arithmetic process, and an abnormality detection signal when an abnormality of the semiconductor light source is detected. Error output to terminal And the microcomputer has an on-duty of a switching signal applied to the switching element as an external interrupt process when the abnormality detection signal is input to the external interrupt terminal. A lighting control circuit for a vehicular lamp, which executes a process for reducing the size of the lamp.

  (Operation) In the process of supplying electromagnetic energy generated from a switching regulator as light emission energy to one or multiple different semiconductor light sources, an abnormality occurs in the semiconductor light source.For example, when the semiconductor light source is disconnected (opened), an abnormality is detected. Since the abnormality detection signal is output from the means, the microcomputer does not perform the arithmetic processing for detecting the abnormality of the semiconductor light source, and the on-duty of the switching signal is changed to the previous on-duty in response to the abnormality detection signal. That is, by controlling the on-duty before the abnormality occurs in the semiconductor light source, it is possible to suppress the output voltage of the switching regulator from becoming excessive, and the circuit elements connected to the switching regulator and the switching regulator And reliably protect semiconductor light sources be able to.

  In the lighting control circuit for the vehicular lamp according to claim 2, a plurality of switching regulators that convert and release the input voltage from the power source into electromagnetic energy by the on / off operation of the switching element connected to the transformer or the coil, A plurality of energy propagation means for propagating electromagnetic energy emitted from the switching regulator as light emission energy to a plurality of different semiconductor light sources, and arithmetic processing related to generation of a switching signal for turning on / off the switching element of each switching regulator. And a microcomputer for controlling the on / off operation of the switching element of each switching regulator based on the result of the arithmetic processing and an abnormality detection signal when the abnormality of each semiconductor light source is detected. A plurality of abnormality detecting means for outputting to an external interrupt terminal and a plurality of signal input terminals corresponding to each of the semiconductor light sources, and the microcomputer is input from any one of the signal input terminals. In accordance with the abnormality detection signal, an abnormal semiconductor light source is determined, and as an external interrupt process in response to the abnormality detection signal input to the external interrupt terminal, the switching regulator of the switching regulator corresponding to the semiconductor light source determined to be abnormal The processing is performed to make the on-duty of the applied switching signal smaller than the previous on-duty.

  (Operation) The switching elements of a plurality of switching regulators are controlled to be turned on and off by a single microcomputer, and the states of a plurality of semiconductor light sources (loads) are monitored. The electromagnetic energy generated from each switching regulator is emitted to each semiconductor light source as light emission energy. When an abnormality occurs in any of the semiconductor light sources during the supply process, an abnormality detection signal is output from the abnormality detection means to the microcomputer. After determining the semiconductor light source in which an abnormality has occurred, it is possible to cope with the semiconductor light source determined to be abnormal without performing arithmetic processing for detecting the light source abnormality using digital data by A / D conversion. The switching elements of the selected switching regulator By executing external interrupt processing, it is possible to quickly suppress the output voltage of the switching regulator from becoming excessive, and to reliably protect the circuit elements and semiconductor light sources connected to the switching regulator and the switching regulator. it can.

  In the lighting control circuit for a vehicular lamp according to claim 3, the switching regulator that converts the input voltage from the power source into electromagnetic energy by the on / off operation of the switching element connected to the transformer or the coil and releases the electromagnetic energy, and the switching regulator A plurality of energy propagation means for propagating the emitted electromagnetic energy as light emission energy to a plurality of different semiconductor light sources, and a calculation process relating to generation of a switching signal for turning on and off the switching element. A microcomputer that controls the on / off operation of the switching element of the switching regulator based on the result, and an abnormality detection signal when an abnormality of each of the semiconductor light sources is detected, an external interrupt terminal among the microcomputer terminals, and the A plurality of abnormality detection means for outputting to a plurality of signal input terminals corresponding to the semiconductor light source, and each energy propagation means has an auxiliary switching element for opening and closing a circuit connecting the switching regulator and each semiconductor light source. The microcomputer executes a calculation process related to generation of a switching signal for sequentially turning on and off the auxiliary switching elements of the energy propagation means, together with generation of switching signals for the switching elements of the switching regulator. In the process of performing control to turn on and off the auxiliary switching elements in order, the abnormal semiconductor light source is determined according to the abnormality detection signal input from any one of the signal input terminals, and the abnormality detection signal input to the external interrupt terminal External in response to As write processing was with the on-duty of the abnormality determined as the switching signal applied to the auxiliary switching elements corresponding to the semiconductor light source formed by executing the processing for less than previous Ondeyutei configuration.

  (Operation) The on / off operation of the switching element of the switching regulator is controlled by one microcomputer, and the auxiliary switching element of each energy propagation means is controlled to be turned on / off in order, and the electromagnetic energy generated from the switching regulator is emitted as the light emission energy. In the process of sequentially supplying to each semiconductor light source (load), when an abnormality occurs in any one of the plurality of semiconductor light sources, for example, the disconnection (open) of the semiconductor light source occurs, the abnormality detection means sends the error to the microcomputer. Since the abnormality detection signal is output, the microcomputer determines the semiconductor light source in which an abnormality has occurred according to the abnormality detection signal, and thereafter detects the abnormality of the semiconductor light source using digital data by A / D conversion. Without performing computations for By executing external interrupt processing immediately for the auxiliary switching element of the energy propagation means corresponding to the semiconductor light source determined to be abnormal, it is possible to quickly suppress the output voltage of the switching regulator from becoming excessive. The circuit elements and semiconductor light sources connected to the switching regulator and the switching regulator can be reliably protected.

  In the vehicle lamp lighting control circuit according to claim 4, the vehicle lamp lighting control circuit according to claim 2 or 3, wherein each of the abnormality detection means is connected to the external interrupt terminal via an OR circuit. It was set as the structure which is connected.

  (Operation) Since each abnormality detection means is connected to the external interrupt terminal of the microcomputer via an OR circuit (OR circuit), the abnormality detection signals from a plurality of abnormality detection means are taken into one external interrupt terminal. be able to.

  As is clear from the above description, according to the lighting control circuit for a vehicular lamp according to the first aspect, even if the semiconductor light source becomes abnormal, the switching regulator, the circuit element connected to the switching regulator, and the semiconductor light source are surely secured. Can be protected.

  According to the lighting control circuit for the vehicular lamp according to the second aspect, even if the semiconductor light source becomes abnormal, it is possible to reliably protect the switching regulator, the circuit element connected to the switching regulator, and the semiconductor light source.

  According to the lighting control circuit for the vehicular lamp according to the third aspect, even when the semiconductor light source becomes abnormal, the circuit element connected to the switching regulator or the switching regulator and the semiconductor light source can be reliably protected.

  According to the fourth aspect of the present invention, abnormality detection signals from a plurality of abnormality detection means can be taken into one external interrupt terminal.

  Next, embodiments of the present invention will be described according to examples. FIG. 1 is a circuit configuration diagram of a lighting control circuit for a vehicular lamp according to an embodiment of the present invention, FIG. 2 is a circuit configuration diagram of a switching element and a drive circuit constituting a switch, and FIG. 3 is an open detection circuit FIG. 4 is a waveform diagram for explaining the process of compare match in the microcomputer. FIG. 5 is a circuit diagram of the lighting control circuit for the vehicular lamp according to the second embodiment of the present invention. 6 is a circuit configuration diagram showing an embodiment when a forward type switching regulator is used, FIG. 7 is a circuit configuration diagram showing an embodiment when a flyback type switching regulator is used, and FIG. 8 is a step-down type. FIG. 9 is a circuit configuration diagram showing an embodiment when a step-up type switching regulator is used. .

  In these drawings, the lighting control circuit 10 for the vehicular lamp is an element of the vehicular lamp (light-emitting device), with respect to LED1, LED2, LED3, LED4, and LED5 as semiconductor light-emitting elements constituting a semiconductor light source. Switching regulators 12, 14, 16, 18, 20; output blocks 22, 24, 26, 28, 30; open detection circuits (disconnection detection circuits) 32, 34, 36, 38, 40; and OR circuits (logical sums) Circuit) 42 and a microcomputer (hereinafter referred to as a microcomputer) 44.

  In addition, instead of LED1 to LED5, as a semiconductor light source serving as a load for each output block 22 to 30, two or more LEDs connected in series with each other or a plurality of LEDs connected in series as a light source block A plurality of light source blocks connected in parallel can also be used. In addition, each semiconductor light source can be configured as a light source for various vehicle lamps such as a headlamp, a stop & tail lamp, a fog lamp, and a turn signal lamp.

  The switching regulators 12, 14, 16, 18, and 20 are configured to include switches (switching elements) SW1, SW2, SW3, SW4, and SW5 and transformers T1, T2, T3, T4, and T5. One end of the primary winding of T5 is connected to the plus terminal of the in-vehicle battery (DC power supply) 46, the other end is connected to the minus terminal of the in-vehicle battery 46 via the switches SW1 to SW5, and both ends of the secondary winding are respectively The output blocks 22, 24, 26, 28 and 30 are connected. Each of the switches SW1 to SW5 is turned on / off in response to a switching signal (pulse signal) from the microcomputer 44. When the switches SW1 to SW5 are turned on, the transformers T1 to T5 accumulate the input voltage from the in-vehicle battery 46 as electromagnetic energy in the primary winding, and the electromagnetic energy accumulated in the primary winding is turned off of the switches SW1 to SW5. Sometimes it is discharged from the secondary side to the output blocks 22-30.

  As the switches SW1 to SW5, for example, as shown in FIG. 2, an NMOS transistor 48 as a switching element can be used. As circuit elements for driving the NMOS transistor 48, resistors R1, R2, an NPN transistor 50, A PNP transistor 52 is provided. The drain of the NMOS transistor 48 is connected to the primary windings of the transformers T1 to T5, and the source is grounded. The bases of the NPN transistor 50 and the PNP transistor 52 are connected to output terminals (signal output terminals) 54, 56, 58, 60, 62 of the microcomputer 44, respectively, so as to constitute a buffer circuit. When a high-level switching signal is output from the microcomputer 44, the NPN transistor 50 is turned on and the NMOS transistor 48 is turned on to accumulate electromagnetic energy in the primary windings of the transformers T1 to T5. It has become. On the other hand, when a low-level switching signal is output from the microcomputer 44, the PNP transistor 52 is turned on and the NMOS transistor 48 is turned off, and the electromagnetic energy accumulated in the primary windings of the transformers T1 to T5 is transferred to the transformers T1 to T1. It discharges to each output block 22-30 from the secondary side of T5.

  The output blocks 22 to 30 are connected to both ends of the LEDs 1 to 5 with the LEDs 1 to 5 as loads, and rectify the electromagnetic energy emitted from the secondary side of the transformers T1 to T5 to the LEDs 1 to 5 as light emission energy. As energy propagating means for propagating, diodes D1, D2, D3, D4, and D5 as rectifying elements that rectify currents output from the secondary sides of the transformers T1 to T5, and capacitors that smooth the output currents of the diodes D1 to D5 C1, C2, C3, C4, and C5. Furthermore, each output block 22-30 is provided with resistors R11, R12, R21, R22, R31, R32, R41, R42, R51, R52 as voltage dividing means for dividing the voltage applied to each LED1-LED5. ing. The resistors R11 and R12 divide the voltage applied to the LED 1 and output the voltage A obtained by the voltage division to the open detection circuit 32. The resistors R21 and R22 divide the voltage applied to the LED 2 and divide the voltage. The voltage B obtained by the pressure is output to the open detection circuit 34, the resistors R31 and R32 divide the voltage applied to the LED 3, and the voltage C obtained by the voltage division is output to the open detection circuit 36, and the resistance R41 and the resistor R42 divide the voltage applied to the LED 4, and output the voltage D obtained by the voltage division to the open detection circuit 38. The resistor R51 and the resistor R52 divide the voltage applied to the LED 5, The voltage E obtained by the voltage division is output to the open detection circuit 40.

  For example, as shown in FIG. 3, the open detection circuits 32 to 40 include resistors R 3, R 4, R 5 and a comparator (comparator) 64 as open detection means (disconnection detection means). The resistors R3 and R4 divide a certain reference voltage and apply the voltage obtained by the voltage division to the negative terminal of the comparator 64. Both ends of the resistor R5 are connected to the negative input terminal and the output terminal of the operational amplifier 64. It is connected. The positive input terminal of the comparator 64 is obtained by dividing the voltage A obtained by dividing the resistors R11 and R12, the voltage B obtained by dividing the resistors R21 and R22, and dividing the resistors R31 and R32. Voltage C, voltage D obtained by dividing the resistors R41 and R42, and voltage E obtained by dividing the resistors R51 and R52 are input. The open detection circuits 32 to 40 compare the voltage (voltage A to voltage E) input to the plus input terminal of the comparator 64 with the reference voltage using the voltage applied to the minus input terminal of the comparator 64 as a reference voltage. When the voltage input to the plus input terminal exceeds the reference voltage, it is assumed that the LEDs 1 to 5 are opened (disconnected), and a high level signal (abnormality detection signal) is sent to the microcomputer 44 via the OR circuit 42 as an external interrupt. In addition to being output to the terminal (IRQ) 66, it is also output to the signal input terminals (I / O1 to I / O5) 68, 70, 72, 74, and 76.

  The OR circuit 42 includes diodes D11, D21, D31, D41, and D51. The anode side of each of the diodes D11 to D51 is connected to the output side of the open detection circuits 32 to 40, and the cathode side is an external interrupt terminal 66. It is connected to the. That is, since the cathode side of each of the diodes D11 to D51 is connected to the external interrupt terminal 66 by wired OR connection to each other, an abnormality detection signal output from the plurality of open detection circuits 32 to 40 is sent via the OR circuit 42. A single external interrupt terminal 66 can be provided. In this case, since the diodes D11 to D51 are inserted between the open detection circuits 32 to 40 and the external interrupt terminal 66, the output signals of the open detection circuits 32 to 40 flow backward to the other open detection circuits. It is possible to prevent malfunction.

  The microcomputer 44 includes a CPU (Central Processing Unit), a RAM, a ROM, an input / output interface, and the like, and an arithmetic process for generating a switching signal for turning on and off the NMOS transistor 48 based on a processing program. And the on / off operation of the NMOS transistor 48 is controlled based on the result of the arithmetic processing. That is, the switching signal obtained by the calculation is output to the NPN transistor 50 and the PNP transistor 52 of the switches SW1 to SW5 via the output terminals 54 to 62. During the process of generating the switching signal, the microcomputer 44 outputs an abnormality detection signal (high level) from one of the open detection circuits 32 to 40 as an external interrupt signal to the external interrupt terminal 66. When the input signal is input, as an external interrupt process, a process for making the on-duty of the switching signal smaller than the previous on-duty (before the opening of any one of LEDs 1 to 5 is detected) is performed. It is supposed to run. When an abnormality detection signal (low level signal) is input, a process for reducing the on-duty may be executed. However, in that case, the relationship between the anodes and cathodes of the diodes D11 to D51 is reversed.

  In the present embodiment, since the microcomputer 44 targets the plurality of switching regulators 12 to 20, any one of the signal input terminals 68 to 76 prior to executing the process for reducing the on-duty of the switching signal. It is determined whether or not an abnormality detection signal (high level signal) is input to the signal input terminal, and the LED corresponding to the signal input terminal to which the abnormality detection signal (high level signal) is input is open (disconnected). A process for determining that it has occurred is performed. And based on this determination result, the process for making the on-duty of the switching signal with respect to the switching regulator corresponding to the open LED smaller than the previous on-duty is executed. For example, when an abnormality detection signal (high level signal) is output from the open detection circuit 32, a high level signal is input only to the signal input terminal 68 among the signal input terminals 68 to 76. Assuming that the LED 1 is opened, a process for reducing the on-duty of the switching signal output from the output terminal 54 as a switching signal for the switch SW1 is executed.

  When the on-duty of the switching signal is reduced, the on-operation time of the NMOS transistor 48 in the switch SW1 is shortened, and the output voltage of the switching regulator 12 can be limited or prevented from being overvoltage. In this case, the on-duty value of the switching signal can be set in association with the allowable current that can protect the NMOS transistor 48. Further, when reducing the on-duty of the switching signal, the NMOS transistor 48 can be completely turned off by setting the on-duty of the switching signal to zero.

  In setting the on-duty of the switching signal in the microcomputer 44, for example, as shown in FIG. 4, when the count value reaches the set value α as a timer counter, the level of the switching signal is changed from “1” to “1”. A timer counter (not shown) for setting to “0” is provided, and a timer counter (not shown) for setting the level of the switching signal from “0” to “1” when the count value reaches the set value β. And starts counting at timing t1 and counts the clock. When the count value reaches the set value α at timing t2 and a compare match occurs, one timer count is reset and the level of the switching signal is set. Set from “1” to “0” and continue counting the clock. The count value is the set value at timing t3. When β is reached, the other timer count is reset, the level of the pulse signal is set from “0” to “1”, and clock counting is started again from timing t3. When the time from the timing t1 to the timing t2 is set to the on-duty and this on-duty is reduced, the on-duty can be reduced by reducing the set value α of one timer counter. Conversely, when increasing the on-duty, the on-duty can be increased by increasing the value of the set value α.

  In the present embodiment, any one of the LEDs 1 to 5 is open (disconnected), and an abnormality detection signal is output from any one of the open detection circuits 32 to 40. This abnormality detection signal is output from the external interrupt terminal 66. When the signal is input to any one of the signal input terminals 68 to 76, the microcomputer 44 does not perform arithmetic processing for A / D conversion of the voltage applied to each LED1 to LED5. The semiconductor light source in which an abnormality has occurred is determined by a signal input to any of the input terminals 68 to 76, and the on-duty of the switching signal is set in response to the abnormality detection signal input to the external interrupt terminal 66. The switch corresponding to the LED (load) in which the abnormality occurred among the switching regulators 12 to 20 It is possible to immediately limit or prevent the output voltage of the regulators 12 to 20 from becoming an overvoltage. The circuit elements constituting the switching regulators 12 to 20 and the circuit elements constituting the output blocks 22 to 30 and the LEDs 1 to LED5 It can be surely protected.

  In this embodiment, the microcomputer 44 controls the switching regulators 12 to 20. However, when the microcomputer 44 controls a single switching regulator, the output of a single open detection circuit is used as a signal. When a high level signal is input from the open detection circuit to the external interrupt terminal 66 without being connected to the input terminals 68 to 76, the microcomputer 44 detects that the abnormal LED ( Without performing the process for determining (load), it is possible to immediately execute the process for making the on-duty of the switching signal smaller than the previous on-duty.

  Furthermore, according to the present embodiment, even if a certain semiconductor light source (LED) becomes abnormal, it is possible to reliably secure the switching regulators 12 to 20 and the circuit elements connected to the switching regulators 12 to 20 and a normal semiconductor light source. Therefore, it is possible to prevent the lighting circuit from being damaged and to secure safety for drivers and pedestrians.

  In the present embodiment, the microcomputer 44 controls the five switching regulators 12 to 20, but the present invention can also be applied to other switching regulators. explain.

  FIG. 5 shows an embodiment when a time-sharing switching regulator 78 is used. The switching regulator 78 includes a transformer T10, a switch SW1 formed of a switching element is connected to the primary winding L1 of the transformer T10, and the output blocks 22 are respectively connected to the secondary windings L21, L22, L23, L24, and L25. 24, 26, 28, and 30 are connected, and LED1, LED2, LED3, LED4, and LED5 are connected to the output blocks 22 to 30, respectively. Each of the output blocks 22 to 30 includes diodes D1, D2, D3, D4, and D5, capacitors C1, C2, C3, C4, and C5, and switches SW21, SW22, SW23, SW24, and SW25 including switching elements. . Furthermore, resistors R11, R12, R21, R22, R31, R32, R41, R42, R51, R52 for dividing the voltage applied to each LED1 to LED5 are provided at both ends of the capacitors C1, C2, C3, C4, C5. Is connected. In this case, the microcomputer 44 generates a switching signal to control the on / off operation of the switch SW1, and controls the switches SW21 to SW25 in turn, and the switching signal is output from the output terminal 54 to the switch SW1. Are output from the output terminals 80, 82, 84, 86, and 88 to the switches SW21 to SW25.

  For example, when controlling the operation of each switch, the switch SW1 is turned on, the input voltage from the in-vehicle battery 46 is accumulated as electromagnetic energy in the primary winding L1, and the accumulated electromagnetic energy is turned off. Sometimes, it is discharged to any one of the output blocks 22-30. That is, when the switch SW1 is turned off, only one of the switches SW21 to SW25 is turned on to rectify the current as the electromagnetic energy emitted from the secondary side of the transformer T10 to emit light energy. Is supplied to any one of the LEDs 1 to 5.

  In this embodiment, when any one of the LEDs 1 to 5 is opened, an abnormal LED (load) is determined by an abnormality detection signal input to any of the signal input terminals 68 to 76, and In response to the abnormality detection signal input to the external interrupt terminal 66, processing for making the on-duty of the switching signal for the switch SW1 smaller than the previous on-duty is performed, and the switches SW21 to SW25 are opened. A process for reducing the on-duty of the switching signal for the switch corresponding to the LED that has become smaller than the previous on-duty is executed. By performing such control, it is possible to limit or prevent the output voltage for an abnormal LED from immediately becoming an overvoltage, to reliably protect the circuit elements and LEDs of the output block, In contrast, a normal current can be continuously supplied.

  FIG. 6 shows an embodiment when a forward switching regulator 90 is used. The switching regulator 90 in this embodiment includes a transformer T11 and a switch SW1, diodes D1 and D2, a coil L1, and a capacitor C1 are connected to the secondary side of the transformer T11, and a resistor R11 and a resistor are connected to both ends of the capacitor C1. R12 and LED1 are connected.

  In this embodiment, when the switch SW1 is on, the electromagnetic energy of the transformer T11 is released to the secondary side, and when the switch SW1 is off, the electromagnetic energy accumulated in the coil L1 is released to the LED1. It has become.

  In this embodiment, when the LED 1 is open and an abnormality detection signal (high level signal) is input from the open detection circuit 32 to the external interrupt terminal 66, the microcomputer 44 sets the on-duty of the switching signal for the switch SW1. By making it smaller, it is possible to immediately limit or prevent the output voltage of the switching regulator 90 from becoming an overvoltage, and it is possible to reliably protect the circuit elements and the LEDs 1 connected to the secondary side of the switching regulator 90. . It is also possible to configure the switching regulator 90 with multiple outputs.

  FIG. 7 shows an embodiment when a flyback switching regulator 92 is used. The switching regulator 92 includes a transformer T12 and a switch SW1, a diode D1 and a capacitor C1 are connected to the secondary side of the transformer T12, and a resistor R11, a resistor R12, and an LED1 are connected to both ends of the capacitor C1. .

  In this embodiment, when the switch SW1 is on, electromagnetic energy is accumulated in the transformer T12. When the switch SW1 is off, the electromagnetic energy accumulated in the transformer T12 is transmitted to the LED1 via the diode D1 and the capacitor C1. Released.

  In this embodiment, when the LED 1 is open and an abnormality detection signal (high level signal) is input from the open detection circuit 32 to the external interrupt terminal 66, the microcomputer 44 sets the on-duty of the switching signal for the switch SW1. By making it small, it is possible to immediately limit or prevent the output voltage of the switching regulator 92 from becoming an overvoltage, and it is possible to reliably protect circuit elements and the LEDs 1 connected to the secondary side of the switching regulator 92. . It is also possible to configure the switching regulator 92 with multiple outputs.

  FIG. 8 shows an embodiment when a step-down switching regulator 94 is used. The switching regulator 94 includes a switch SW1, a diode D1, a coil L1, and a capacitor C1, and a resistor R11, a resistor R12, and LED1 are connected to both ends of the capacitor C1.

  In this embodiment, when the switch SW1 is turned on, the input voltage is accumulated as electromagnetic energy in the coil L1, and when the switch SW1 is turned off, the diode D1 is turned on and the electromagnetic wave accumulated in the coil L1. Energy is released to the LED 1.

  In this embodiment, when the LED 1 is open and an abnormality detection signal (high level signal) is input from the open detection circuit 32 to the external interrupt terminal 66, the microcomputer 44 sets the on-duty of the switching signal for the switch SW1. By making it small, it is possible to immediately limit or prevent the output voltage of the switching regulator 94 from becoming an overvoltage, and it is possible to reliably protect the circuit elements of the switching regulator 94 and the LED 1.

  FIG. 9 shows an embodiment when a step-up switching regulator 96 is used. The switching regulator 96 includes a coil L1, a switch SW1, a diode D1, and a capacitor C1, and a resistor R11, a resistor R12, and LED1 are connected to both ends of the capacitor C1.

  In this embodiment, when the switch SW1 is turned on, the input voltage is accumulated in the coil L1 as electromagnetic energy, and when the switch SW1 is turned off, the electromagnetic energy accumulated in the coil L1 is superimposed on the input voltage. Thus, the light is emitted to the LED 1 through the diode D1 and the capacitor C1.

  In this embodiment, when the LED 1 is open and an abnormality detection signal (high level signal) is input from the open detection circuit 32 to the external interrupt terminal 66, the microcomputer 44 sets the on-duty of the switching signal for the switch SW1. By making it small, it is possible to immediately limit or prevent the output voltage of the switching regulator 96 from becoming an overvoltage, and it is possible to reliably protect the circuit elements of the switching regulator 96 and the LED 1.

It is a circuit block diagram of the lighting control circuit of the vehicle lamp which shows one Example of this invention. It is a circuit block diagram of the switching element which comprises a switch, and its drive circuit. It is a circuit block diagram of an open detection circuit. It is a wave form diagram for demonstrating the process of the compare match in a microcomputer. It is a circuit block diagram of the lighting control circuit of the vehicle lamp which shows 2nd Example of this invention. It is a circuit block diagram which shows an Example when the switching regulator by a forward system is used. It is a circuit block diagram which shows an Example when the switching regulator by a flyback system is used. It is a circuit block diagram which shows an Example when a pressure | voltage fall type switching regulator is used. It is a circuit block diagram which shows an Example when a step-up type switching regulator is used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle lighting control circuit 12, 14, 16, 18, 20 Switching regulator 22, 24, 26, 28, 30 Output block 32, 34, 36, 38, 40 Open detection circuit 42 OR circuit 44 Microcomputer 54, 56 58, 60, 62 Output terminal 66 External interrupt terminal 68, 70, 72, 74, 76 Signal input terminal 78, 90, 92, 94, 96 Switching regulator

Claims (4)

A switching regulator that converts an input voltage from a power source into electromagnetic energy by an on / off operation of a switching element connected to a transformer or a coil and releases the electromagnetic energy, and one or a plurality of different electromagnetic energy emitted from the switching regulator as emission energy A microcomputer that executes energy calculation means for propagating to the semiconductor light source, and a calculation process related to generation of a switching signal for turning on and off the switching element, and controls the on / off operation of the switching element based on the result of the calculation process And an abnormality detection means for outputting an abnormality detection signal to an external interrupt terminal of the microcomputer when an abnormality of the semiconductor light source is detected, and the microcomputer detects the abnormality detection signal at the external interrupt terminal. When it is a force, outside as interrupt processing, the lighting control circuit of a vehicular lamp comprising running processing to be smaller than Ondeyutei on-duty earlier it switching signal applied to the Sutchingu element. A plurality of switching regulators that convert the input voltage from the power source into electromagnetic energy and release it by turning on and off the switching elements connected to the transformer or the coil, and a plurality of different types of electromagnetic energy emitted from each switching regulator as light emission energy A plurality of energy propagation means each propagating to the semiconductor light source, and a calculation process related to generation of a switching signal for turning on and off the switching element of each switching regulator, and each switching regulator based on the result of the calculation process A microcomputer for controlling the on / off operation of the switching element, and an abnormality detection signal when an abnormality of each semiconductor light source is detected, an external interrupt terminal among the terminals of the microcomputer and each semiconductor light source A plurality of abnormality detection means for outputting to each of a plurality of corresponding signal input terminals, and the microcomputer determines an abnormal semiconductor light source according to the abnormality detection signal input from any one of the signal input terminals, and the external As an external interrupt process in response to the abnormality detection signal input to the interrupt terminal, the on-duty of the switching signal applied to the switching element of the switching regulator corresponding to the semiconductor light source determined to be abnormal is more than the previous on-duty. A lighting control circuit for a vehicular lamp, which executes processing for reducing the size. A switching regulator that converts an input voltage from a power source into electromagnetic energy by an on / off operation of a switching element connected to a transformer or a coil and emits it, and a plurality of semiconductor light sources different from each other using the electromagnetic energy emitted from the switching regulator as light emission energy A plurality of energy propagating means each propagating to the switching element and a calculation process relating to generation of a switching signal for turning on and off the switching element, and controlling the on / off operation of the switching element of the switching regulator based on the result of the calculation process An abnormality detection signal when detecting an abnormality of each of the semiconductor light sources and an external interrupt terminal among the microcomputer terminals and a plurality of signal input terminals corresponding to the respective semiconductor light sources, respectively A plurality of anomaly detection means that act, each energy propagation means has an auxiliary switching element that opens and closes a circuit connecting the switching regulator and each semiconductor light source, and the microcomputer switches the switching regulator Along with generation of switching signals for the elements, calculation processing related to generation of switching signals for sequentially turning on / off the auxiliary switching elements of the energy propagation means is executed, and control for turning on / off the auxiliary switching elements is executed. In the process, the abnormal semiconductor light source is determined according to the abnormality detection signal input from any one of the signal input terminals, and the external interrupt processing in response to the abnormality detection signal input to the external interrupt terminal is determined as the abnormality. Semiconductor light source Lighting control circuit response to the auxiliary vehicle lamp the on-duty of the switching signal obtained by executing the processing to be smaller than previous Ondeyutei applied to the switching element. The lighting control circuit for a vehicle lamp according to claim 2 or 3, wherein each abnormality detecting means is connected to the external interrupt terminal via an OR circuit. circuit.

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