JP2011068185A - Vehicular lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the power loss and to reduce the manufacturing cost, and to protect a switching power supply circuit. <P>SOLUTION: A vehicular lamp includes a light source 12, and a light emission device 2 having a switching power supply circuit 5 and a control circuit 6. The switching power supply circuit 5 is non-insulating, and a switch element 3 for starting and stopping the supply of the input voltage from a battery 14 is arranged between a power supply input terminal 20 and the switching power supply circuit 5. The control circuit 6 has an output detection unit 7 for detecting the drive voltage or the drive current of the switching power supply circuit 5, and an input detection unit 11 for detecting the input voltage. The switch element 3 is controlled so as to stop the supply of the input voltage if the detected drive voltage or drive current exceeds the predetermined threshold, or the detected input voltage exceeds the predetermined threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicular lamp having a non-insulated switching power supply circuit that supplies a driving voltage or driving current to a light source.

Some vehicle lamps use a semiconductor light emitting element such as a light emitting diode (LED) or a discharge lamp as a light source. Such a vehicular lamp is provided with a switching power supply circuit that converts an input voltage from a battery into a driving voltage and supplies the converted driving voltage to turn on the light source (see, for example, Patent Document 1). .
Since a large current flows from the input side when a short circuit or a ground fault occurs on the output side, the switching power supply circuit is generally configured as an insulation type.

JP 2006-206001 A

  However, the isolated switching power supply circuit has different current loops on the input side and output side, so the input voltage is more efficient than the non-isolated switching power supply circuit that outputs most of the input voltage to the light source. Can not be converted.

  Therefore, the insulation type switching power supply circuit has a problem that power loss increases.

  On the other hand, when a non-insulated type having a switching element with a low withstand voltage is used as a switching power supply circuit, in addition to when a large current flows when a short circuit or a ground fault occurs on the output side, for example, on the input side Even when an overvoltage such as a load dump is applied from the battery, there is a possibility that the low-voltage switching element or the like may be destroyed.

  Accordingly, an object of the present invention is to reduce power loss and protect a switching power supply circuit.

  The vehicular lamp according to the first aspect of the present invention includes a light source, a switching power supply circuit that receives an input voltage from a power input terminal and supplies a driving voltage or a driving current to the light source via a driving output terminal, and the driving voltage or the A light emitting device having a control circuit for controlling a drive current, the switching power supply circuit being non-insulated, and a switch for starting and stopping the supply of the input voltage between the power supply input terminal and the switching power supply circuit An element is disposed, and the control circuit includes an output detection unit that detects the drive voltage or the drive current and an input detection unit that detects the input voltage, and the detected drive voltage or the drive current is predetermined. The switch element so that the supply of the input voltage is stopped when the threshold value of the input voltage is exceeded or when the detected input voltage exceeds the predetermined threshold value. Controls, control voltage input to the control power supply for operating the control circuit is obtained so as to be supplied from between the supply input terminal and the switching element.

  Accordingly, the switch element is controlled so that the supply of the input voltage is stopped when an overvoltage is supplied from the input side of the switching power supply circuit and an overvoltage or overcurrent is supplied from the output side.

  A vehicle lamp according to a second aspect of the present invention includes a light source, a switching power supply circuit that receives an input voltage from a power supply input terminal and supplies the drive voltage or drive current to the light source via a drive output terminal, and the drive voltage or A light emitting device having a control circuit for controlling the drive current, wherein the switching power supply circuit is non-insulated, and is connected between the switching power supply circuit and the light source, and the drive voltage or the drive current is a predetermined threshold value When the value exceeds the value, a shut-off element that cuts off the supply of the drive voltage or the drive current to the light source is provided.

  Therefore, when an overvoltage or overcurrent is supplied from the output side of the switching power supply circuit, the cutoff element is melted and the supply of the input voltage is stopped.

  The vehicle lamp according to the present invention includes a light source, a switching power supply circuit that receives an input voltage from a power supply input terminal and supplies the drive voltage or drive current to the light source via the drive output terminal, and a control that controls the drive voltage or the drive current. A switching element that starts and stops the supply of the input voltage between the power supply input terminal and the switching power supply circuit, and the switching power supply circuit is configured to be non-insulated. The control circuit has an output detection unit that detects the drive voltage or the drive current and an input detection unit that detects the input voltage, and the detected drive voltage or drive current exceeds a predetermined threshold value Alternatively, the switch element is controlled to stop the supply of the input voltage when the detected input voltage exceeds a predetermined threshold, and the control is performed. Control voltage input to the control power supply for operating the circuit is characterized in that it is supplied from between the supply input terminal and the switching element.

  Therefore, since the input voltage can be converted into the output voltage with high efficiency, the power loss can be reduced.

  Further, since an inexpensive device such as a switching element having a low withstand voltage characteristic can be used, the manufacturing cost can be reduced.

  Further, since the overcurrent and overvoltage to the switching power supply circuit can be interrupted on the input side, the switching power supply circuit can be protected.

  Another vehicle lamp of the present invention includes a light source, a switching power supply circuit that receives an input voltage from a power supply input terminal and supplies the drive voltage or drive current to the light source via a drive output terminal, and the drive voltage or drive current. A light emitting device having a control circuit to control, the switching power supply circuit is configured to be non-insulated, and connected between the switching power supply circuit and the light source, and the driving voltage or the driving current exceeds a predetermined threshold Further, a shut-off element that cuts off the supply of the drive voltage or the drive current to the light source is provided.

  Therefore, since the input voltage can be converted into the output voltage with high efficiency, the power loss can be reduced.

  Further, since an inexpensive shut-off element can be used, the manufacturing cost can be reduced.

  In addition, since the supply of the input voltage is stopped when the drive voltage or drive current supplied to the interruption element exceeds a predetermined threshold value, the overcurrent to the switching power supply circuit is interrupted to protect the switching power supply circuit. it can.

  In the invention described in claim 3, since the interruption element is a pattern fuse or a wire bond, when the supplied drive voltage or drive current exceeds a predetermined threshold value, the input voltage from the battery is reliably detected. Supply can be stopped.

  In the invention described in claim 4, since the light source is composed of a light emitting diode, and the switching power supply circuit and the control circuit are fixed on the same substrate, the light source, the switching power supply circuit and the control circuit are provided. This eliminates the need for a connector for connecting the, and can reduce the manufacturing cost.

  Below, 1st Embodiment of the vehicle lamp of this invention is described with reference to FIG.

  As shown in FIG. 1, the vehicular lamp 1 includes a light emitting device 2 and a light source 12.

The light-emitting device 2 includes power input terminals 20 and 21, output terminals 22 and 23, a switch element 3, a non-insulated switching power supply circuit 5, a shunt resistor R _SH , a capacitor C, and a control circuit 6. It functions as a voltage / current supply means for supplying a driving voltage or a driving current. As the light source 12, for example, an LED (Light Emitting Diode) or a discharge lamp that functions as a semiconductor light source is used.

  The switch element 3 is disposed between the power input terminal 20 and the switching power supply circuit 5 and starts and stops the supply of the input voltage supplied via the power input terminal 20 when turned on and off. As the switch element 3, for example, an NMOS (Negative Channel Metal Oxide Semiconductor) transistor, a PMOS (Positive Channel Metal Oxide Semiconductor) transistor, or the like is used.

  As the non-insulated switching power supply circuit 5, for example, a circuit using a chopper circuit including a coil or a flyback circuit using a chopper circuit including a transformer is used. For example, a flyback switching power supply circuit includes a transformer, a capacitor, a diode, and an NMOS transistor.

  Both ends of the capacitor C are connected to power input terminals 20 and 21, respectively. The power input terminal 20 is connected to the positive terminal of the battery 14 via the switch 15, and the power input terminal 21 is connected to the negative terminal of the battery 14.

  The control circuit 6 includes an output detection unit 7, a drive control unit 8, an input detection unit 9, a control power supply 10, and a switch control unit 11.

  The output detection unit 7 is connected to the drive control unit 8 and the switch control unit 11 and detects a drive voltage or a drive current that is an output of the switching power supply circuit 5. The detected drive voltage or drive current is sent to the drive control unit 8 and the switch control unit 11.

  The input detection unit 9 is connected to the switch control unit 11 and detects the input voltage of the switching power supply circuit 5. The detected input voltage is sent to the switch control unit 11.

  The drive control unit 8 is connected to the switching power supply circuit 5 and has a function of controlling the output of the switching power supply circuit 5 according to the detected drive voltage or drive current.

  The switch control unit 11 is connected to the switch element 3 and controls on / off of the switch element 3 according to the detection results of the output detection unit 7 and the input detection unit 9.

  The control power supply 10 is connected to a node between the switch element 3 and the power supply input terminal 20 and supplies a control voltage for operating the control circuit 6.

  Below, operation | movement of the light-emitting device 2 which comprises the vehicle lamp which concerns on this 1st Embodiment is demonstrated.

Output detector 7 is delivered to the shunt resistor R drive voltage or drive current detection drives and controls the detected driving voltage or driving current portion 8 in the _SH and the switch control unit 11.

  The input detection unit 9 detects the input voltage and sends the detected input voltage to the switch control unit 11.

  The drive control unit 8 feedback-controls the switching power supply circuit 5 so that the drive voltage or drive current sent to the light source 12 in response to the detected drive voltage or drive current has a predetermined value.

  The switch control unit 11 compares the detected input voltage with a predetermined first threshold value, and supplies the supply stop control signal Sk to the switch element 3 when the detected input voltage exceeds the first threshold value. Send it out. The first threshold value is preset and stored in a memory (not shown) in the switch control unit 11 so that the voltage at the power input terminal 20 is equal to or less than a normal voltage value that is not an overvoltage.

  Further, the switch control unit 11 compares the detected drive voltage or drive current with a predetermined second threshold value, and when the detected drive voltage or drive current exceeds the second threshold value, the switch element 3 is supplied with a supply stop control signal Sk. The second threshold value is set in advance and stored in the memory so that the voltage at the output terminal 22 is equal to or lower than the normal voltage value or current value when the voltage is not overvoltage or overcurrent.

  The switch element 3 receives the supply stop control signal Sk and is turned off so as to stop the supply of the input voltage. For example, when the switch element 3 is an NMOS transistor, the switch element 3 is turned off when the low-level supply stop control signal Sk is sent to the gate of the NMOS transistor, and the input voltage is supplied to the switching power supply circuit 5. Stops. When the switch element 3 is a PMOS transistor, when the high-level supply stop control signal Sk is sent to the gate of the PMOS transistor, the switch element 3 is turned off and the input voltage is supplied to the switching power supply circuit 5. Stops.

  As described above, in the vehicular lamp 1, current and voltage are detected by both the input detection unit 9 on the input side of the switching power supply circuit 5 and the output detection unit 7 on the output side, and the detected drive is detected. When the voltage or drive current exceeds a predetermined second threshold, or when the detected input voltage exceeds the predetermined first threshold, the switch element 3 is controlled to stop supplying the input voltage. is doing. Therefore, overcurrent and overvoltage to the switching power supply circuit 5 can be cut off on the input side, and the switching power supply circuit can be protected.

  Further, as described above, in the vehicular lamp 1, since the non-insulated type is used as the switching power supply circuit 5, the following two effects can be obtained. First, since the input voltage can be converted into the output voltage with high efficiency, the power loss can be reduced. Secondly, since devices such as switching elements having low withstand voltage characteristics are included, these devices are inexpensive and the manufacturing cost can be reduced.

  Below, 2nd Embodiment of the vehicle lamp of this invention is described with reference to FIG.2 and FIG.3.

  As shown in FIG. 2, the vehicular lamp 30 includes a light emitting device 32, a pedestal 48 that fixes the light emitting device 32, a projection lens 46 that projects emitted light forward, and a lens holder that holds the projection lens 46. 47 and a reflector 33 that opens forward.

  The light emitting device 32 includes, for example, a light source 42 that is an LED, a substrate 43 on which the light source 42 is mounted, a connector 44 for connecting a battery to be described later, and a circuit board 45 on which the substrate 43 and the connector 44 are mounted. Yes. The light source 42 may be a light source other than the LED. When the light source 42 is, for example, a discharge lamp, the discharge lamp is not mounted on the circuit board 45 but is connected to the circuit board 45 via a predetermined connector.

  The circuit configuration of the light emitting device 32 will be specifically described below.

As shown in FIG. 3, the light emitting device 32 includes power input terminals 50 and 51, output terminals 52 and 53, a non-insulated switching power supply circuit 35, a shunt resistor R _SH , a capacitor C, a control circuit 36, and a cutoff element. The pattern fuse 39 and the light source 42 are provided, and function as voltage / current supply means for supplying a drive voltage or drive current to the light source 42. The light source 42, the switching power supply circuit 35, and the control circuit 36 are fixed on the circuit board 45 so that they cannot be removed from the circuit board 45 (see FIG. 2). The pattern fuse 39 or a wire bond described later is fixed to the circuit board 45.

  As the non-insulated switching power supply circuit 35, for example, a circuit using a chopper circuit including a coil as in the switching power supply circuit 5 shown in FIG. 1 or a flyback type using a chopper circuit including a transformer is used. It is done.

  Both ends of the capacitor C are connected to power input terminals 50 and 51, respectively. The power input terminal 50 is connected to the plus terminal of the battery 54 via the switch 55, and the power input terminal 51 is connected to the minus terminal of the battery 54.

  The control circuit 36 includes an output detection unit 37, a drive control unit 38, and a control power supply 40.

Pattern fuse 39 is blown when connected to the driving voltage or the driving current exceeds a predetermined threshold value is supplied between the shunt resistor R _SH and the light source 42 arranged on the output side of the switching power supply circuit 35. The interrupting element may be other than a pattern fuse as long as it is blown when a driving voltage or driving current exceeding a predetermined threshold is supplied. For example, a wire bond may be used. . As the wire bond, for example, an ultrafine metal wire made of a material such as gold, aluminum, or copper is used. The threshold value is set by changing the wire bond diameter.

  The output detection unit 37 is connected to the drive control unit 38 and detects a drive voltage or a drive current that is an output of the switching power supply circuit 35. The detected drive voltage or drive current is sent to the drive control unit 38.

  The drive control unit 38 is connected to the switching power supply circuit 35 and has a function of controlling the output of the switching power supply circuit 35 in accordance with the detected drive voltage or drive current.

  The control power supply 40 is connected to the input side of the switching power supply circuit 35 and supplies a control voltage for operating the control circuit 36.

  Below, operation | movement of the light-emitting device 32 which comprises the vehicle lamp which concerns on this 2nd Embodiment is demonstrated.

Output detection unit 37 sends a driving voltage or a driving current is detected by detecting the driving voltage or driving current in shunt resistor R _SH to the drive control unit 38.

  The drive control unit 38 feedback-controls the switching power supply circuit 35 so that the drive voltage or drive current sent to the light source 42 in response to the detected drive voltage or drive current has a predetermined value.

  The pattern fuse 39 is blown when the supplied drive voltage or drive current is larger than a predetermined threshold. The predetermined threshold value is set in advance so that the voltage at the output terminal 52 is equal to or less than the normal voltage value or current value that is not an overvoltage or overcurrent generated by a short circuit, ground fault, or the like.

  When the drive voltage or drive current greater than the predetermined threshold is supplied and the pattern fuse 39 is blown, the supply of the input voltage supplied from the battery 54 to the switching power supply circuit 35 is stopped.

  As described above, in the vehicular lamp 30, when the drive voltage or drive current supplied to the pattern fuse 39 disposed on the output side of the switching power supply circuit 35 exceeds a predetermined threshold, the input voltage is reduced. Supply stops. Therefore, the overcurrent and overvoltage to the switching power supply circuit 35 are cut off, and safety such as prevention of ignition of internal devices constituting the switching power supply circuit 35 can be improved, and the switching power supply circuit 35 can be protected. it can.

  Further, since the vehicle lamp 30 also uses the non-insulated switching power supply circuit 35, the same effect as the vehicle lamp 1 in the first embodiment described above, that is, reduction of power loss and manufacturing cost. Can be reduced.

  Further, since the light source 42, the switching power supply circuit 35, and the control circuit 36 are fixed on the circuit board 45 so that they cannot be removed from the same circuit board 45, the light source 42, the switching power supply circuit 35, and the control circuit 36 are connected. No connector (harness or the like) is required, and the inexpensive pattern fuse 39 is used as the interrupting element, so that the manufacturing cost can be reduced.

  The above-described embodiment is merely an example of a preferred embodiment of the present invention, and the present invention can be implemented with various modifications without departing from the gist thereof.

It is the figure which showed the circuit structure of the vehicle lamp which concerns on the 1st Embodiment of this invention. It is the perspective view which showed the structure of the vehicle lamp which concerns on the 2nd Embodiment of this invention. It is the figure which showed the circuit structure of the vehicle lamp which concerns on the 2nd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1,30 ... Vehicle lamp, 2, 32 ... Light-emitting device, 3 ... Switch element, 6, 36 ... Control circuit, 5, 35 ... Switching power supply circuit, 7, 37 ... Output detection part 10, 40 ... Control power supply , 11 ... input detection unit, 12, 42 ... light source, 20 ... power input terminal

Claims (4)

A light source including a light source, a switching power supply circuit that receives an input voltage from a power supply input terminal and supplies the drive voltage or drive current to the light source via a drive output terminal, and a control circuit that controls the drive voltage or drive current In the vehicular lamp provided,
The switching power supply circuit is non-insulated,
A switch element for starting and stopping the supply of the input voltage is disposed between the power supply input terminal and the switching power supply circuit,
The control circuit includes an output detection unit that detects the drive voltage or the drive current and an input detection unit that detects the input voltage, and the detected drive voltage or the drive current exceeds a predetermined threshold value. Or if the detected input voltage exceeds a predetermined threshold, the switch element is controlled to stop supplying the input voltage,
The vehicle lamp, wherein a control voltage input to a control power source for operating the control circuit is supplied from between the switch element and the power input terminal. Light emitting device comprising: a light source; a switching power supply circuit that receives an input voltage from a power supply input terminal and supplies the drive voltage or drive current to the light source via a drive output terminal; and a control circuit that controls the drive voltage or drive current With
The switching power supply circuit is non-insulated,
A blocking element connected between the switching power supply circuit and the light source and configured to cut off the supply of the driving voltage or the driving current to the light source when the driving voltage or the driving current exceeds a predetermined threshold. A vehicular lamp characterized by the above. The vehicular lamp according to claim 2, wherein the blocking element is a pattern fuse or a wire bond. 4. The vehicular lamp according to claim 1, wherein the light source includes a light emitting diode, and the switching power supply circuit and the control circuit are fixed on the same substrate. .

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