JP4459147B2 - Vehicle lamp failure detection device and lamp unit - Google Patents

Description

  The present invention relates to a vehicle lamp failure detection device and a lamp unit effective for detecting and notifying a failure of a vehicle direction indicator lamp or the like.

  In a direction indicator lamp of an automobile as a vehicle, a flashing relay or the like flashes at a predetermined cycle in response to a signal from an operation switch that selects left and right direction indications. When the direction indicator lamp breaks down (disconnection, etc.), it becomes a poorly maintained vehicle, so it is necessary to notify the driver of the failure. As a conventional vehicle lamp body failure detection device, for example, there is one used for a trailer (see, for example, Patent Document 1).

  An example of a circuit in such a failure detection apparatus for a vehicle lamp is shown in FIG. In the illustrated circuit, a direction indicating operation switch 2 having two position selection contacts 2b and 2c is connected to a positive terminal of a battery BT as a power source via a flasher relay unit 21, and each selection contact 2b and 2c of the operation switch 2 is connected. A plurality of lamps 24, 25, and 26 are connected to the left and right via separate wiring cables (wire harnesses) 3. In the illustrated circuit, a front lamp 24 at the front of the vehicle, a side lamp 25 at the side, and a rear lamp 26 at the rear are provided on the left and right respectively. What is shown is shown.

  In the flasher relay unit 21, a shunt resistor Rs and an on-contact 8a at the time of excitation of the relay 8 are connected in series to a power supply line connecting the positive terminal of the battery BT and the common terminal 2c of the operation switch 2. The coil 8 b of the relay 8 is excited by an output signal from the control circuit 27. The output signal is normally a pulse signal of the first cycle T1, and the coil repeats excitation and de-excitation in the cycle T1, thereby causing the lamps 24, 25 and 26 on the side selected by the operation switch 2 to flash. To do. Further, the control circuit 27 performs current detection by the shunt resistor Rs.

When one of the lamps 24 to 26 is disconnected, the current that flows changes. Therefore, when the change is detected by the shunt resistor Rs, the control circuit 27 outputs, for example, a second period T2 that is half of the first period T1. The pulse signal is output. The user can know the disconnection by blinking the lamp at an earlier cycle.
JP 2000-264127 A

  However, in each of the lamps 24, 25, and 26, a light bulb is used. For example, the capacity of the front and rear lamps 24 and 26 is 21 watts, and the capacity of the side lamp 25 is 5W. Therefore, the current change is small when the small-capacity side lamp 25 is disconnected, and the disconnection cannot be detected by the disconnection detection. The same applies to the case where a lamp body using a light emitting diode in recent years is used. If the existing light bulb is simply replaced with a light emitting diode, the load current will be about ½ or less. Therefore, the current change width becomes small, and there is a problem that it is difficult to detect disconnection in current detection.

  Also, in disconnection detection by shunt resistance, the threshold for disconnection detection changes according to the amount of current consumed by the load (lamp), so a separate threshold is set according to the specifications of each vehicle or the value of shunt resistance There is a problem that the design becomes complicated due to the necessity of changing the operation. In particular, when the trailer is used as in Patent Document 1, the number of lamps is greatly different between towing and non-towing, and thus the above problem is remarkable. In addition, when a light emitting diode is employed, the degree of freedom in designing the lamp body is increased, and the number of light emitting diodes used may vary from vehicle type to vehicle type, further increasing the opportunity for design changes.

  In addition, there is a structure in which a signal line for disconnection detection is provided separately from the power supply line of the lamp body. However, since the wiring is bulky and the existing wiring (wire harness) cannot be diverted, a new design is designed for each vehicle type. There is a problem that it must be fixed.

  In order to solve such a problem and realize a vehicle lamp failure detection apparatus that can divert existing wiring and can detect disconnection of a small-capacity lamp body, A control circuit that can output a first pulse signal having a cycle and a second pulse signal having a second cycle different from the first cycle, and outputting the pulse signal having the first cycle in a normal state; Switch means connected to the control circuit so as to be turned on and off in response to outputs of the first and second pulse signals, and an operation switch connected to a power supply for supplying a first voltage via a contact of the switch means A plurality of lamps including light emitting diodes connected to the ON contact of the operation switch in parallel via a wiring cable and capable of emitting light when the voltage of the wiring cable exceeds a second voltage lower than the first voltage. unit Failure detecting means for detecting disconnection or short failure of the light emitting diode, and a predetermined first voltage lower than the second voltage at which the light emitting diode can emit light when the failure is detected in any of the light emitting diodes. And a failure voltage generating means for outputting the third voltage to the wiring cable and not outputting the third voltage when the light emitting diode is normal, and turning off the first or second pulse signal. A failure detection circuit that detects whether or not the third voltage is sometimes generated in the wiring cable and outputs a detection signal to the control circuit when the third voltage is detected, The control circuit outputs the pulse signal of the second period when the detection signal is input from the failure detection circuit.

  In particular, the failure-time voltage generating means includes a capacitor provided to be charged when the pulse signal is turned on and discharged when the pulse signal is turned off when the light-emitting diode fails, and a charging voltage of the capacitor is set to the first voltage. It is preferable to have a constant voltage element specified to a voltage of 3.

  In addition, the lamp unit is connected to the plurality of light emitting diodes connected in series to each other via the wiring cable to the ON contact of the operation switch, and the voltage of the wiring cable is the first voltage. When the lower second voltage is exceeded, the lighting means that is turned on to supply current to the light emitting diode, and the second light emitting diode that can emit light when any of the plurality of light emitting diodes fails. It is preferable to have a failure voltage generating means for outputting a predetermined third voltage lower than the voltage to the wiring cable and not outputting the third voltage when the light emitting diode is normal.

  The lighting means includes a switch element connected in series with the light emitting diode, and is connected to the switch element and connected to the wiring cable, and when the voltage of the wiring cable exceeds the second voltage, A first constant voltage element that is turned on together with the switch element is preferably included.

  According to the present invention, there is provided a lamp unit including a light emitting diode as a lamp unit, which is connected to a wiring cable supplied with a first voltage from a power source, and the voltage of the wiring cable is a first voltage. When the lighting device that is turned on when a lower second voltage is exceeded and supplies current to the light emitting diode, a failure detecting device that detects a failure in which the light emitting diode is disconnected or short-circuited, and the light emitting diode fails When a failure occurs in which a predetermined third voltage lower than the second voltage at which the light emitting diode can emit light is output to the wiring cable and the third voltage is not output when the light emitting diode is normal. Voltage generation means.

  In particular, the light emitting diode includes a first light emitting diode group composed of a plurality of light emitting diode elements connected in series to each other, and a plurality of light emitting diode elements connected in series to each other and the first light emitting diode group A second light emitting diode group connected in parallel is preferably included.

  Thus, according to the present invention, for example, when a light emitting diode is used as a light source in a direction indicating lamp as a vehicle lamp, and the light is turned on / off according to the pulse signal of the first cycle, In the event of a failure, a predetermined low voltage (third voltage) lower than the light emission possible voltage (second voltage) is output from the lamp body to the wiring cable, and the failure detection circuit generates that low voltage when the pulse signal is turned off. When a failure is detected, a pulse signal of the second period is output, so that when a failure occurs, other normal lamps are turned on and off in a second period different from the normal state, so that no separate signal detection wiring is required. Failure detection using existing wiring (wire harness) can be performed. Note that even if a low voltage is generated in the wiring cable when the pulse signal is turned off, the other light emitting diodes are not lit at the low voltage, so that the light can be turned on / off in the second period.

  In addition, instead of detecting the change in current at the time of disconnection, the low voltage is returned to the control circuit side at the time of disconnection, and the presence or absence of the low voltage is detected when the pulse signal is turned off. It is suitable for a device using a light emitting diode which is not affected and has a smaller current than a light bulb. Further, a small-capacity side lamp, which has been difficult with current detection, can be detected without any problem, and disconnection can be detected for all of the direction indicating lamps.

  In particular, the disconnection can be detected with a simple circuit configuration by providing a capacitor for generating a low voltage at the time of disconnection, charging when the pulse signal at the time of disconnection is on, and discharging at the time of off.

  Further, the lamp unit has a plurality of light emitting diodes connected in series with each other, and has lighting means for turning on the light emitting diodes when the second voltage is exceeded. Thus, the circuit can be configured, and versatility is enhanced. In particular, the determination of the second voltage by the lighting means can be performed easily by using a constant voltage element, and the circuit can be simplified, which is effective when handled as a lamp unit.

  In addition, by configuring the lamp unit with the lighting means, the failure detection means, and the failure voltage generation means, it is not necessary to provide a failure detection signal line or the like in the wiring to the lighting control circuit, and an existing wiring cable ( Since the wiring structure for lighting the lamp body with the wire harness can be used, it can be applied to various vehicle lamp circuits without changing the wiring route. In particular, a plurality of light emitting diodes connected in series are connected in parallel to constitute the light emitting diode of the lamp unit, and thus can be applied to various light emitting diode layouts.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a direction indication control circuit of a motorcycle, for example, to which the present invention is applied, and includes a vehicle lamp failure detection device to which the present invention is applied. In the figure, the same parts as those shown in FIG. 9 as conventional circuits are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the figure, the flasher relay unit 1, the operation switch 2, and the left and right wiring cables (wire harnesses) 3 are connected to a power supply line connected to the positive terminal of the battery BT as a power supply, as in the conventional circuit. is there. A front lamp unit 4, a side lamp unit 5, and a rear lamp unit 6 are connected to each wiring cable 3 wired along the left and right sides of the vehicle in parallel with each other.

  The front and rear lamp units 4 and 6 use a lamp that consumes a large amount of power, while the side lamp unit 5 uses a lamp that consumes a relatively small amount of power. It is done. The lamp used in each lamp unit 4, 5, 6 is a light emitting diode.

  In the flasher relay unit 1, a control circuit 7 having a built-in transmission circuit, a relay 8 as a relay means, and a failure detection circuit 9 are provided. Further, as external connection terminals of the flasher relay unit 1, a power supply terminal 1a connected to the battery BT, an output terminal 1b connected to the common terminal 2a of the operation switch 2, and a ground terminal 1c are provided.

  An ON contact 8a when the relay 8 is energized is connected between the power supply terminal 1a and the output terminal 1b, the power supply terminal of the control circuit 7 is connected to the power supply terminal 1a, and the ground terminal of the control circuit 7 is connected to the ground terminal 1c. It is connected. A pulse signal having a first period (T1) and a second period (T2) that is different from the period is selectively output from the output terminal of the control circuit 7, and the coil 8b of the relay 8 is pulsed by the output. Excitation and de-excitation are repeated according to the signal cycle. In the normal state, a pulse signal of the first period that is the blinking speed of the vehicle direction indicator lamp is output.

  Outside the flasher relay 1, the output terminal 1 b and the common terminal 2 a of the operation switch 2 are connected via the same connection line (wire harness) 10 as the existing one used in the conventional vehicle. Further, the above-described wiring cable 3 may be an existing one used in a conventional vehicle and may have the same wiring path. For example, the right wiring cable 3 is connected to the ON contact 2b when one of the operation switches 2 is selected, and the left wiring cable 3 is connected to the ON contact 2c when the other is selected.

  A hazard switch 11 is provided in parallel with the operation switch 2. By turning on the hazard switch 11, the output terminal 1b and each wiring cable 3 are connected even when the operation switch 2 is in the off state. When the operation switch 2 and the hazard switch 11 are turned on, the control circuit 7 is also activated by the interlocked switch (not shown), and a pulse signal is output.

  Next, the lamp units 4, 5, 6 connected to the wiring cable 3 as described above will be described with reference to FIG. As described above, the lamp units 4, 5, and 6 are the same for the front and rear lamp units 4 and 6, and the side lamp unit 5 has the same circuit configuration with a small capacity. FIG. 2A shows the front lamp unit 4 on the right side as a representative, and description of the other parts is omitted.

  The lamp unit 4 is provided with a power supply terminal 4a and a ground terminal 4b connected to the wiring cable 3. A plurality of light emitting diodes LED1, LED2, and LED3 connected in series to each other are connected to the power supply terminal 4a. The collector of the first transistor Tr1 is connected to the ground side via a diode D2. Note that the emitter of the first transistor Tr1 is grounded. Connected between the power supply terminal 4a and the base of the first transistor Tr1 is a first Zener diode ZD1 that defines the lighting voltage of the light emitting diodes LED1, LED2, and LED3. The first transistor Tr1 and the first Zener diode ZD1 constitute lighting means. A second transistor Tr2, a resistor R1, and a capacitor C are connected in series in this order between the power supply terminal 4a and the ground terminal 4b, and a third transistor Tr3 that constitutes a failure detection means is connected in parallel with the capacitor C. Has been. The base terminal of the third transistor Tr3 is connected to the connection point between the light emitting diodes LED1, LED2, LED3 and the diode D2. The base terminal of the PNP-type second transistor Tr2 is connected to the collector terminal of the first transistor Tr1, and the second transistor Tr2 is controlled by the first transistor Tr1. Further, the anode of the second Zener diode ZD2 is connected to the ground terminal 4b, the anode of the diode D1 is connected to the cathode of the second Zener diode ZD2, and the cathode of the diode D1 is connected to the power supply terminal 4a. The connection point between the second Zener diode ZD2 and the diode D1 is connected to the + terminal of the capacitor C via the resistor R2.

  In the lamp unit 4 configured as described above, the operation switch 2 is operated to the on-contact 2b side when selected, and the common terminal 2a and the contact 2b are brought into an electrically conductive state. The battery voltage is applied to the power supply terminal 4a when the pulse signal of the period T1 shown is on. The battery voltage is lowered to a predetermined constant voltage VL by the first Zener diode ZD1, a voltage is applied to the base via the first Zener diode ZD1, the transistor Tr1 is turned on, and currents are supplied to the light emitting diodes LED1, LED2, and LED3. Flows, and the light emitting diodes LED1, LED2, and LED3 emit light. The Zener voltage VL defined by the first Zener diode ZD1 is set to a voltage that can turn on the first transistor Tr1, for example, 7 volts.

  In this normal state, when the first transistor Tr1 is turned on, current flows through the light emitting diodes LED1, LED2, and LED3 and the second transistor Tr2 is turned on, and current flows through the light emitting diodes LED1, LED2, and LED3. The transistor Tr3 is also turned on. Since the current flowing from the second transistor Tr2 via the resistor R1 flows to the third transistor Tr3, the capacitor C is not charged. The voltage of the power supply terminal 4a of the lamp unit 4 is a constant voltage VH (see FIG. 3).

  Here, a case where any one of the light emitting diodes LED1, LED2, and LED3 is disconnected (failed) will be described. In this case, one lamp unit (for example, the right front side) is disconnected, and the other lamp units are normal. Referring to FIG. 2A, when any one of the light emitting diodes LED1, LED2, and LED3 is disconnected, the first transistor Tr1 is turned on when the pulse signal supplied from the power supply terminal 4a is turned on. Then, the second transistor Tr2 is turned on, but since no current flows through the light emitting diodes LED1, LED2, and LED3, the third transistor Tr3 is turned off, and the capacitor C is caused by the current flowing from the second transistor Tr2 through the resistor R1. Charged. The charging voltage of the capacitor C is regulated by the Zener voltage Vz of the second Zener diode ZD2. For example, the zener voltage Vz is 5 volts. The voltage of the power supply terminal 4a of the lamp unit 4 at this time, that is, the constant voltage VH is 12 volts.

  Next, when the pulse signal is off, the third transistor Tr3 is off, and the voltage Vz charged in the capacitor C is supplied from the charged capacitor C through the diode D1 to the power supply terminal 4a. The Zener voltage Vz of the second Zener diode ZD2 is selected to be smaller than the Zener voltage VL of the first Zener diode ZD1, and the first Zener diode ZD1 is not turned on by the discharge voltage Vz from the capacitor C. The transistor Tr1 is not turned on, and no current flows through the light emitting diodes LED1, LED2, and LED3. This low voltage Vz is supplied to the wiring cable 3. Therefore, the voltage Vz is also applied to the power terminals of the other lamp units 4 to 6, but is lower than the Zener voltage VL of the first Zener diode ZD1 of the other normal lamp units 4 to 6. The lamp units 4 to 6 do not emit light.

  The low voltage Vz supplied to the power supply terminal 4a is detected by the failure detection circuit 9 in the flasher relay unit 1. The detection procedure is shown in the example of FIG. In the illustrated example, the output terminal 1b is connected to one of a pair of input terminals of an AND circuit 9a constituting the failure detection circuit 9, and the pulse signal output of the control circuit 7 is inverted and input to the other input terminal of the AND circuit 9a. ing. Thereby, when the pulse signal is turned off, a high level signal is output from the AND circuit 9a according to the potential of the output terminal 1b. The output signal of the AND circuit 9a is input to the control circuit 7. The control circuit 7 stops the signal of the first period T1, generates a signal of the second period T2, and sends the signal of the second period T2 to the relay 8. Supply. Note that the input threshold value of the AND circuit is selected to be 2 volts. Further, the charging time constant (R1 × C) of the capacitor C is selected to be about the first period T1, and the discharging time constant (R2 × C) of the capacitor C is selected to be sufficiently larger than the first period T1. Yes.

  When the relay 8 is turned on / off by the signal of the second period T2, the pulse signal of the second period T2 is supplied to the wiring cable 3, and the lamp units 4, 5, and 6 are provided with light emitting diodes that are not broken down. Flashes in the second period T2. Among the lamp units 4, 5, and 6, those having a failed light emitting diode continue to supply the low voltage Vz to the wiring cable 3 when the pulse signal is off.

  Further, the lamp unit 4 in the present invention is not limited to the illustrated example, and as shown in FIG. 2B, the light emitting diodes LED1, LED2, and LED3 in the illustrated example are mutually connected. For example, a first light-emitting diode group LEDa, a second light-emitting diode group LEDb, and a third light-emitting diode group LEDc composed of, for example, four light-emitting diodes may be connected in parallel to the power supply terminal 4a. In this example, the same parts as those in FIG. 2A are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the illustrated example, the base terminals of the respective PNP transistors Tr5a, Tr5b, Tr5c provided in correspondence with the anodes of the diodes D2 corresponding to the light emitting diode groups LEDa, LEDb, LEDc are connected to the power source. A connection node between the terminal 4a and each transistor Tr5a, Tr5b, Tr5c is connected to the base terminal of the transistor Tr3. Thereby, in the normal time of each light emitting diode group LEDa, LEDb, LEDc, a constant voltage is applied to the base terminal of each transistor Tr5a, Tr5b, Tr5c via each corresponding light emitting diode group LEDa, LEDb, LEDc. The voltage of the power supply terminal 4a is divided by a resistor and applied to the emitter terminals of the transistors Tr5a, Tr5b, Tr5c as a constant voltage. At this time, the relationship between the voltages applied to the base-emitter terminals of the transistors Tr5a, Tr5b, Tr5c is Ve <Vb (Ve is the emitter terminal voltage, Vb is the base terminal voltage), and the transistors Tr5a, Tr5b , Tr5c is not turned on.

  On the other hand, at the time of open failure of each light emitting diode group LEDa, LEDb, LEDc, the base terminal of the corresponding one of the transistors Tr5a, Tr5b, Tr5c is in the ground state (0V), so the voltage applied to the base-emitter terminal Therefore, Ve> Vb is established, and the corresponding transistors Tr5a, Tr5b, Tr5c are turned on, whereby the transistor Tr3 is turned off. As a result, a failure detection state similar to the above is obtained. Thus, even in the lamp unit 4 in which the light emitting diode groups LEDa, LEDb, and LEDc are connected in parallel, the same effects as described above can be obtained.

  Next, the 2nd example of each lamp unit 4,5,6 is shown with reference to Fig.4 (a). The same parts as those in the example of FIG. 2A are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second example, a plurality of light emitting diodes LED1, LED2, and LED3 connected in series with each other are connected to the power supply terminal 4a, and the emitter is grounded via a diode D2 on the ground side. A first transistor Tr1 is connected, and a first Zener diode ZD1 for regulating the voltage of the wiring cable 3 at which the light emitting diodes LED1, LED2, and LED3 start lighting is connected between the power supply terminal 4a and the base terminal of the first transistor Tr1. Has been. The second transistor Tr2 and the capacitor C, and the PNP type fourth transistor Tr4 and the fifth transistor Tr5 are connected in series between the power supply terminal 4a and the ground terminal 4b. The capacitor C and the third transistor Tr3 are connected in parallel, and the base terminal of the third transistor Tr3 is connected to a connection node between the fourth transistor Tr4 and the fifth transistor Tr5. The base terminal of the fourth transistor Tr4 is connected to the cathode of the diode D2 via the third Zener diode ZD3. Note that the Zener voltage of the third Zener diode ZD3 is selected to be approximately the same as the total value of the forward voltage drop values of the light emitting diodes LED1, LED2, and LED3. The base terminal of the fifth transistor Tr5 is connected to the anode of the diode D2.

  In the lamp unit 4 configured in this way, during normal lighting, when the first transistor Tr1 is turned on, the second transistor Tr2 and the fourth transistor Tr4 are turned on. When the fourth transistor Tr4 is turned on, the third transistor Tr3 is also turned on, and the current flowing through the second transistor Tr2 does not accumulate in the capacitor C. Note that the PNP transistor Tr5 is off at this time.

  On the other hand, when one of the light emitting diodes is disconnected, the second transistor Tr2 and the fourth transistor Tr4 are turned on when the first transistor Tr1 is turned on while the pulse signal is on, but the light emitting diode is disconnected. A current flows from the base terminal of the fifth transistor Tr5 to the first transistor Tr1 via the diode D2, and the fifth transistor Tr5 is turned on. In this way, failure detection means for detecting disconnection is configured. As a result, the current flowing through the fourth transistor Tr4 flows to the fifth transistor Tr5 and the base current of the third transistor Tr3 does not flow, so the third transistor Tr3 is turned off, and the capacitor C is charged. As in the first example (FIG. 2A), a low voltage Vz lower than the Zener voltage VL of the first Zener diode ZD1 can be supplied to the wiring cable 3 when the pulse signal is off.

  When the first transistor Tr1 is turned on in the ON state of the power supply pulse at the time of short-circuit failure of the light-emitting diode, the voltage drop in the light-emitting diodes LED1, LED2, and LED3 is reduced by the number of fast-acting diodes that are short-circuited. Since the Zener voltage of the third Zener diode ZD3 is selected to be substantially the same as the total value of the forward drop voltages of the respective light emitting diodes LED1, LED2, LED3, the third Zener increases when the cathode voltage value of the diode D2 increases. The diode ZD3 is turned off. As a result, the fourth transistor Tr4 is turned off, and as a result, the third transistor Tr3 is turned off. In this way, failure detection means for detecting a short circuit is configured. Then, the capacitor C is charged through the second transistor Tr2, and as in the first example, the low voltage Vz lower than the Zener voltage VL of the first Zener diode ZD1 is applied to the wiring cable 3 when the pulse signal is turned off. Can be supplied to.

  The voltage Vz is also applied to the power terminals of the other lamp units 4 to 6, but is lower than the Zener voltage VL of the first Zener diode ZD1 of the other normal lamp units 4, 5, and 6, so The body units 4, 5, 6 do not emit light.

  As in the first example, the low voltage Vz supplied to the power supply terminal 4a is detected by the above-described failure detection circuit 9 in the flasher relay unit 1. Thereby, when the pulse signal is turned off, a high level signal is output from the AND circuit 9a according to the potential of the output terminal 1b. The output signal of the AND circuit 9a is input to the control circuit 7. The control circuit 7 stops the signal of the first period T1, generates the signal of the second period T2, and supplies it to the relay 8.

  When the relay 8 is turned on / off by the signal of the second period T2, the pulse signal of the second period T2 is supplied to the wiring cable 3, and the lamp unit 4 or 5 or 6 including the light emitting diode that has not failed is in the second period T2. Flashes. The lamp unit 4 or 5, 6 including the failed light emitting diode continues to supply the low voltage Vz to the wiring cable 3 when the pulse signal is off.

  In this way, when the low voltage Vz is generated at the output terminal 1b when the pulse signal is turned off, the detection signal is output from the AND circuit 9a, and the detection signal is input to the control circuit 7. In the control circuit 7, when the detection signal of the AND circuit 9 a is input, the control circuit 7 determines that any of the lamp units 4 or 5, 6 is in a failure state, and the second is used to notify the user of the disconnection. A pulse signal with period T2 is output. The second period T2 is, for example, half of the first period T1. The voltage waveform of the power supply terminal 4a of the lamp unit 4 in this state is the state on the right side of FIG. That is, when the pulse signal is turned on in the second period T2, it is the power supply voltage VH, and when the pulse signal is turned off, it is the low voltage Vz defined by the second Zener diode ZD2.

  FIG. 4B shows the first example corresponding to the parallel connection shown in FIG. 2B. Also in this figure, the same parts as those in the illustrated example are denoted by the same reference numerals, and detailed description thereof is omitted. Each Zener diode directly connected to each of the diode groups LEDa, LEDb, and LEDc to the Zener diode ZD3 for short circuit failure detection is for backflow prevention. In the circuit of FIG. 4B as well, the disconnection and short-circuit failure of any one of the light emitting diodes can be detected in the same manner as in FIG.

  In this illustrated example, as in FIG. 2B, the PNP transistors Tr5a, Tr5b, Tr5c provided corresponding to the anodes of the diodes D2 corresponding to the light emitting diode groups LEDa, LEDb, LEDc, respectively. Are connected, and a connection node between the power supply terminal 4a and each of the transistors Tr5a, Tr5b, Tr5c is connected to the base terminal of the transistor Tr3. A constant voltage is applied to the emitter terminals of the transistors Tr5a, Tr5b, Tr5c via the transistor Tr4. In this example as well, the relationship between the voltages applied to the base-emitter terminals of the transistors Tr5a, Tr5b, Tr5c at normal times is Ve <Vb, and the transistors Tr5a, Tr5b, Tr5c are not turned on. On the other hand, when an open failure occurs in each of the light emitting diode groups LEDa, LEDb, and LEDc, Ve> Vb is established, and the corresponding transistors Tr5a, Tr5b, and Tr5c are turned on, thereby turning off the transistor Tr3. As a result, a failure detection state similar to the above is obtained.

  In the present circuit, the existing wiring cables 10 and 3 between the flasher relay unit 1 and the lamp units 4, 5 and 6 can be used as described above, and even in such a case, the light emitting diodes are used. It is possible to detect a disconnection when using the lamp unit without any problem and to perform a process of notifying a failure as in the conventional case. Further, in the case of detecting the disconnection by detecting the current change in the power supply line using a conventional light bulb, the disconnection cannot be detected because the current changes only slightly when the side lamp of a small capacity (for example, 5 W) is disconnected. On the other hand, in the present invention, since the predetermined low voltage Vz is returned to the failure detection circuit 9 at the time of pulse-off, disconnection of each lamp unit can be detected regardless of the magnitude of the current capacity of the load.

  Further, the present invention is not limited to the direction indicator circuit of a motorcycle, and can be applied to a direction indicator circuit in a trailer, for example. Conventional current detection type failure detection devices are difficult to handle because the current capacity changes as the number of lamps increases. In the failure detection device of the present invention, since the low voltage Vz generated when each lamp unit fails is detected, failure detection is possible regardless of the current capacity. Thus, it is possible to cope with the case where the number of lamps, that is, the current capacity during lighting changes greatly. Furthermore, it is not necessary to change the wire harness as described above.

  Next, another example of the failure detection circuit is shown in FIGS. In addition, the same code | symbol is attached | subjected to the part similar to the said example of illustration, and the detailed description is abbreviate | omitted. The third example of FIG. 5 has a configuration in which a comparator 9b is added to the AND circuit 9a in the first example. The comparator 9b uses the comparator 9b to set the voltage of the output terminal 1b to a predetermined low voltage Vz or higher. And outputs the detection output to the control circuit 7 via the AND circuit 9a. Other operations are the same as those in the first example, and the same effects are obtained.

  In the fourth example of FIG. 6, the AND circuit 9a is eliminated, and the pulse signal of the control circuit 7 is input to the reference voltage input terminal of the comparator 9b via the diode D3. Thereby, a high voltage (for example, battery BT voltage) is applied to the reference voltage input terminal of the comparator 9b via the diode D3 when the pulse signal is turned on, and the high voltage is compared with the voltage of the output terminal 1b. When the voltage at the output terminal 1b is the power supply voltage VH, the detection signal is not output from the comparator 9b because the voltages of the two input signals of the comparator 9b are equal. On the other hand, at the time of failure, when the pulse signal is turned off, the diode D3 is turned off and a low voltage Vz exceeding the reference voltage Vr is generated at the output terminal 1b. A detection signal is output from the comparator 9 b to the control circuit 7. Also in this case, other operations are the same as those in the first example, and the same effect is obtained.

  The direction indication control circuit according to the present invention is a method of blinking operation with a single relay 8 in FIG. 1, which is an explanatory diagram thereof, but is not limited to this, for example, as shown in FIG. The same applies to the structure in which a plurality of structures are used. In the illustrated example, a right direction instruction operation switch SWR and a left direction instruction operation switch SWL, and a hazard switch 11 provided in parallel therewith are provided between the battery BT and the control circuit 7. In the flasher relay unit 1, the right and left relays 8 are provided independently and in parallel with each other, and the right lamp units 4 corresponding to the respective on-contacts 8 a during excitation, 5 and 6 and the lamp units 4, 5 and 6 for the left side are connected via the respective wiring cables 3. The right side and left side failure detection circuits 9 are provided in parallel in the flasher relay unit 1. Thus, even when the relay 8 and the failure detection circuit 9 are provided independently for the right side and the left side, the failure detection operation is the same as in the illustrated example.

  FIGS. 8 (a) and 8 (b) show a part of the circuit shown in FIGS. 2 (a) and 2 (b), respectively. In addition, the same code | symbol is attached | subjected about the part similar to the above, and the detailed description is abbreviate | omitted. Since these circuits also operate in the same manner as described above and show modifications of the circuit, description of connection of each element is omitted. Moreover, it cannot be overemphasized that there exists the same effect.

1 is a direction instruction control circuit diagram of a motorcycle to which the present invention is applied. FIG. (A) is a figure which shows the circuit of a lamp unit, (b) is a figure which shows the example which connected the light emitting diode group of (a) in parallel. It is a figure which shows the waveform at the time of the normal time of a pulse signal, and a disconnection. (A) It is a figure corresponding to Drawing 2 (a) showing the 2nd example of a lamp unit in the present invention, and (b) is a figure corresponding to Drawing 2 (b) showing the 2nd example. It is a figure which shows the 3rd example of a failure detection apparatus. It is a figure corresponding to FIG. 4 which shows the 4th example of a failure detection apparatus. FIG. 6 is another directional support control circuit diagram of the motorcycle to which the present invention is applied. (A) It is a figure which shows the modification corresponding to FIG. 2 (a) of a lamp unit, (b) is a figure which shows the modification corresponding to FIG.2 (b). It is a conventional direction indication control circuit diagram.

Explanation of symbols

1 Flasher Relay Unit 2 Operation Switch 3 Wiring Cables 4, 5, 6 Lamp Unit 7 Control Circuit 8 Relay 9 Failure Detection Circuit ZD1 First Zener Diode ZD2 Second Zener Diode C Capacitor

Claims (6)

A control circuit capable of outputting a first pulse signal of a first period and a second pulse signal of a second period different from the first period and outputting the pulse signal of the first period in a normal state;
Switch means connected to the control circuit to turn on and off in response to the outputs of the first and second pulse signals;
An operation switch connected via a contact of the switch means to a power supply for supplying a first voltage;
A plurality of lamp units connected to the ON contact of the operation switch in parallel with each other via a wiring cable and having a light emitting diode capable of emitting light when a voltage of the wiring cable exceeds a second voltage lower than the first voltage; ,
Fault detection means for detecting disconnection or short fault of the light emitting diode;
When the failure is detected in any of the light emitting diodes, a predetermined third voltage lower than the second voltage at which the light emitting diode can emit light is output to the wiring cable, and the light emitting diode is normal. In the case of failure voltage generating means that does not output the third voltage,
When the first or the second pulse signal is turned off, it is detected whether the third voltage is generated in the wiring cable, and when the third voltage is detected, the detection signal is sent to the control circuit. Fault detection circuit that outputs to
When the detection signal is input from the failure detection circuit, the control circuit outputs the pulse signal of the second period, and the vehicle lamp failure detection device is characterized in that:   The failure voltage generating means is provided such that when the light emitting diode fails, the capacitor is charged when the pulse signal is turned on and discharged when the pulse signal is turned off, and the charging voltage of the capacitor is set to the third voltage. The vehicle lamp body failure detection device according to claim 1, further comprising a constant voltage element that regulates the voltage. A plurality of light emitting diodes connected in series with each other via a wiring cable to the ON contact of the operation switch;
A lighting means connected to the distribution cable, which turns on when the voltage of the distribution cable exceeds the second voltage lower than the first voltage and supplies current to the light emitting diode;
When one of the plurality of light emitting diodes fails, a predetermined third voltage lower than a second voltage at which the light emitting diode can emit light is output to the wiring cable, and when the light emitting diode is normal The failure detection device for a vehicular lamp according to claim 1, further comprising a failure-time voltage generation unit that does not output the third voltage.   The lighting means includes a switching element connected in series with the light emitting diode, and is connected to the switching element and connected to the wiring cable. When the voltage of the wiring cable exceeds the second voltage, the switching element The vehicle lamp body failure detection device according to claim 3, further comprising: a first constant voltage element that is turned on at the same time. A lamp unit having a light emitting diode as a lamp,
A light source that is connected to a wiring cable to which a first voltage from a power source is supplied and that turns on when the voltage of the wiring cable exceeds a second voltage lower than the first voltage to supply current to the light emitting diode. Means,
Failure detection means for detecting a failure in which the light emitting diode is disconnected or short-circuited;
When the light emitting diode fails, a predetermined third voltage lower than a second voltage at which the light emitting diode can emit light is output to the wiring cable, and when the light emitting diode is normal, the third voltage is applied. A lamp unit having a failure-time voltage generating means that is in a state of not outputting.   The light emitting diode includes a first light emitting diode group composed of a plurality of light emitting diode elements connected in series to each other, and a plurality of light emitting diode elements connected in series to each other and in parallel with the first light emitting diode group. The lamp unit according to claim 5, further comprising a second light emitting diode group connected thereto.

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