JP2010221842A - Lighting fixture for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve safety during vehicle driving by maintaining the lighting of an LED having a light distribution function even when an LED having a decoration function is in open abnormality. <P>SOLUTION: The lighting fixture 1 for a vehicle has: an indicator lamp unit 3 provided with LEDs 10, having a light distribution function and LEDs 11, having a decoration function and serially connected to the LEDs 10; a DC/DC converter 6 for supplying LED drive current I<SB>L</SB>to the indicator lamp unit 3; and a lighting maintaining circuit 9 having an NMOS transistor Tr1. The NMOS transistor Tr1 is controlled in such a way as to maintain the lighting of the LEDs 10, when the LEDs 11, go off because of malfunction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field for controlling lighting of a light source unit including a semiconductor light source having a light distribution function and a semiconductor light source having a decoration function in a vehicular lamp.

  2. Description of the Related Art Conventionally, as a vehicular lamp, for example, a light source unit configured by connecting a light emitting diode (LED) as a semiconductor light source having a light distribution function and an LED as a semiconductor light source having a decoration function in series, A device including a switching regulator as a current supply unit that supplies an LED driving current as a light source driving current to the light source unit and a control unit that controls the output voltage of the switching regulator is known (for example, Patent Document 1). reference).

JP 2004-136719 A

  In the above-described conventional vehicle lamp, when an LED having a decoration function becomes an open abnormality such as disconnection, both the LED having the light distribution function and the LED having the decoration function are turned off. Therefore, when only the LED having the decoration function becomes an open abnormality, the LED having the light distribution function is turned off in spite of the normality, and there arises a problem that the safety when the vehicle is traveling is lowered.

  Accordingly, an object of the present invention is to maintain the lighting of the LED having the light distribution function even when the LED having the decoration function becomes an open abnormality, and to improve the safety during traveling of the vehicle.

  A vehicle lamp according to an aspect of the present invention includes a light source unit including a first semiconductor light source having a light distribution function and a second semiconductor light source connected in series to the first semiconductor light source and having a decoration function; A current supply unit that supplies a light source driving current to the light source unit; and a lighting maintenance unit that includes a lighting maintenance switch connected to the first semiconductor light source and the second semiconductor light source and controls the light source driving current. When the first semiconductor light source becomes abnormal and turns off, the second semiconductor light source is turned off, and when the second semiconductor light source becomes abnormal and turns off, the first semiconductor light source is kept on. Thus, the lighting maintenance switch is controlled.

  Therefore, the lighting maintenance switch is controlled so as to maintain the lighting of the first semiconductor light source when the second semiconductor light source is abnormal.

  A vehicular lamp according to the present invention includes a light source unit including a first semiconductor light source having a light distribution function and a second semiconductor light source connected in series to the first semiconductor light source and having a decoration function; A current supply unit that supplies a light source drive current; and a lighting maintenance unit that includes a lighting maintenance switch connected to the first semiconductor light source and the second semiconductor light source, and controls the light source driving current, The second semiconductor light source is turned off when one semiconductor light source is abnormal and turned off, and the first semiconductor light source is kept on when the second semiconductor light source is abnormal and turned off. The lighting maintenance switch is controlled.

  Therefore, even when only the semiconductor light source having the decoration function becomes abnormal, the lighting of the semiconductor light source having the light distribution function is maintained, so that it is possible to improve safety when the vehicle is traveling.

  In the invention described in claim 2, since a resistor having a predetermined resistance value is disposed between the first semiconductor light source and the second semiconductor light source, only the semiconductor light source having a decoration function is provided. Even when an open abnormality occurs, the light source driving current having a current value determined by the resistance is supplied to the semiconductor light source having the light distribution function, so that the lighting of the semiconductor light source having the light distribution function is reliably maintained and the vehicle travels. The safety at the time can be reliably improved.

  According to a third aspect of the present invention, the lighting maintenance switch is an NMOS transistor that is turned on when the second semiconductor light source becomes abnormal, and the light source driving is performed when the NMOS transistor is turned on. A current flows to the ground through the resistor, and the current value of the light source driving current increases as the on-voltage of the NMOS transistor increases.

  Therefore, even when only the semiconductor light source having the decoration function becomes an open abnormality, the light source driving current having a current value determined by the resistance is supplied to the semiconductor light source having the light distribution function, and then the gate source voltage of the NMOS transistor is increased. Accordingly, the light source driving current increases, so that the lighting of the semiconductor light source having the light distribution function is reliably maintained, and the safety can be reliably improved when the vehicle is traveling.

  In the invention described in claim 4, since the daytime running lamp that lights up in the time zone other than night time and exhibits the sign function is used as the light source unit, it is continuously in the time zone other than night time. The lighting of the daytime running lamp, which is often lit, is reliably maintained, and the safety can be reliably improved when the vehicle is running.

  The vehicle lamp according to the first embodiment of the present invention will be described below.

  The vehicular lamps 1 and 1 are respectively attached to the left and right end portions of the front end portion of the vehicle. As shown in FIG. 1, the vehicular lamp 1 includes a lamp body (not shown) having a concave portion opened forward, and a cover 14 that closes the opening surface of the lamp body. An internal space formed by the lamp body and the cover 14 is formed as a lamp chamber 15.

  The lamp chamber 15 is provided with a marker lamp unit 3 that is arranged from the front to the side of the vehicle and functions as a light source, and a headlamp unit 12 that includes an LED 13. As shown in FIG. 2, the vehicular lamp 1 has a lighting control unit 2 connected to a marker lamp unit 3.

The lighting control unit 2 includes a DC / DC converter 6 as a current supply unit, a shunt resistor _RSH , a current detection unit 7, a control unit 8, and a lighting maintenance circuit 9 as a lighting maintenance unit. ing.

  The beacon lamp unit 3 is a so-called daytime running lamp unit that lights up in a time zone other than night time, that is, a time zone before and after sunrise to a time zone before and after sunset. A first light source 4 having LEDs 10, 10... As a first semiconductor light source having a function and a second light source 5 having LEDs 11, 11. And. The marker lamp unit 3 is not limited to a daytime running lamp, but may be another marker lamp such as a clearance lamp or a turn signal lamp.

DC / DC converter 6 is fed to the indication lamp unit 3 through the high-side output terminal 22 of the LED drive current I _L by receiving the lighting control signal St from the control unit 8.

Control unit 8, the constant current control to the current value of a predetermined control current by the shunt resistor R _SH and the current detection unit 7 control unit 8 a current value of the detected LED drive current I _L through the Is going.

  Further, the output voltage is detected by a value obtained by dividing by the resistors R9 and R10, and overvoltage limit control is performed so that the output voltage does not exceed a predetermined value. The value of the overvoltage limit is set to a value sufficiently higher than the total value of the forward voltage Vf and the voltage drop at the resistor R4 of the LEDs 10, 10,. Yes.

  The lighting maintenance circuit 9 includes a grounded NMOS transistor Tr1, a collector grounded PNP transistor Tr2, a grounded emitter NPN transistor Tr3, resistors R1 to R8, and a capacitor C as lighting maintenance switches.

  The drain of the NMOS transistor Tr1 is connected to the cathode of the LED 10 through the intermediate output terminal 23 and to the anode of the LED 11 through the intermediate output terminal 24. The gate of the NMOS transistor Tr1 is connected to the collector of the NPN transistor Tr3 through the resistor R8 and is connected to the control power supply Vcc through the resistor R3.

  One end of the resistor R1 is connected to the cathode of the LED 10 through the intermediate output terminal 23 and is connected to the anode of the LED 11 through the intermediate output terminal 24, and the other end is grounded.

  The base of the PNP transistor Tr2 is connected to the cathode of the LED 11 via the low-side output terminal 25, and the emitter is connected to the base of the NPN transistor Tr3 via the resistor R6 and to the control power supply Vcc via the resistor R5. Yes.

  The operation of the lighting control unit 2 in the vehicle lamp 1 will be described below with reference to FIG. FIG. 3 is a time chart for explaining the operation of the lighting control unit 2. In FIG. 3, section A indicates a section in which the LEDs 11, 11,... Having the decoration function are normal, and section B to section F indicate sections in which the LEDs 11, 11,. ing. In the example of FIG. 3, the LEDs 11, 11,... Become open abnormal at the start point of section B, the power is turned off at the start point of section D, and the power is turned on at the start point of section E. Time t1 is a time determined by the time constant of the resistor R3 and the capacitor C.

When the power source of the battery (not shown) is turned on, the DC / DC converter 6 starts control so as to have a predetermined LED drive current value, so that the output voltage Vo is the forward voltage Vf of the LEDs 10, 10,. rises to a voltage determined by, LED drive current _{I L} based on the output voltage Vo is supplied to LED10,10 · · · through the shunt resistor _{R SH} LED10,10 ··· is illuminated (see section a). LED10,10 LED drive current _{I L} supplied to ... are also supplied to LED11,11 ... via the intermediate output terminal 23.

In section A of Figure 3, in order to flow through the LED driving current _{I L} in LED11,11 ···, PNP transistor Tr2 voltage resistor R4 occurred NPN transistor Tr3 off operation is turned on. When the NPN transistor Tr3 is turned on, the NMOS transistor Tr1 is turned off.

Accordingly, the LED drive current _{I L} flowing through the LED10,10 · · · flows in LED11,11 ···, LED10,10 ··· and LED11,11 · · · are both turned (see section A).

Next, a case where the LEDs 10, 10... Are normal but the LEDs 11, 11,... Become open abnormal will be described (section B to section F). When LED11,11 · · · is open fault, the NMOS transistors Tr1 immediately is turned OFF, to flow to ground through the LED drive current _{I L} is the resistance R1 that flows from LED10,10 ···, DC / The output voltage Vo of the DC converter 6 becomes an overvoltage limit value. Therefore, even immediately after the LED11,11 · · · becomes open fault, LED10,10 · for LED drive current _{I L} which is determined by the forward voltage Vf and the resistor R1 overvoltage limit value and LED10,10 · · · flows .. can be prevented from turning off (see section B).

Therefore, the current value of the LED drive current I _L is controlled to be smaller than the current value of the control current by the resistor R1. For this reason, the output voltage Vo of the DC / DC converter 6 rises to the overvoltage limit value, and then the output voltage Vo is maintained at a constant voltage (overvoltage limit value) (see section B).

In Section B, the order does not flow LED drive current _{I L} in LED11,11 ···, the voltage at the resistor R4 PNP transistor Tr2 becomes zero is turned on, NPN transistor Tr3 is turned OFF. When the NPN transistor Tr3 is turned off, the gate-source voltage Vgs of the NMOS transistor Tr1 starts to rise.

  The NMOS transistor Tr1 enters an on state (a state in which the on voltage has been exceeded) after a predetermined time has elapsed after starting the on operation (start point of the section B) (point a in the section C). That is, the gate-source voltage Vgs of the NMOS transistor Tr1 gradually increases during the time t1 determined by the time constant of the resistor R3 and the capacitor C, and the NMOS transistor Tr1 is turned on at a point a in the section C.

LED drive current I _L, as shown in Section B, the decreased current value determined by the resistor R1 after the output voltage Vo of the DC / DC converter 6 becomes overvoltage limit value, the subsequent rise of the gate-source voltage Vgs It increases with it. Then, the current value of the LED drive current I _L is constant and increases to the current value of the control current in the (see section C).

  The time constants of the resistor R3 and the capacitor C are set so as to be sufficiently later than the control delay time in the feedback loop of the feedback means composed of the DC / DC converter 6, the current detector 7 and the controller 8. Is preferred. This is because if the time constant of the resistor R3 and the capacitor C is faster than the control delay time, the constant current control by the feedback means described above may not be possible.

  Further, it is desirable that the resistance value of the resistor R8 be set sufficiently smaller than the resistance value of the resistor R3. This is because if the resistance value of the resistor R8 is greater than or equal to the resistance value of the resistor R3, the NMOS transistor Tr1 may not be turned off even when the NPN transistor is turned on.

Thereafter, the output voltage Vo of the turning off the power of the battery DC / DC converter 6 becomes zero, LED drive current _{I L} is not supplied to any of LED10,10 · · · and LED11,11 ··· (section D see ).

Then again even after power of the battery, LED11,11 · · · open abnormality because is not eliminated LED drive current to LED11,11 ··· _{I L} does not flow. Accordingly, the voltage at the resistor R4 becomes zero, the PNP transistor Tr2 is turned on, and the NPN transistor Tr3 is turned off. When the NPN transistor Tr3 is turned off, the gate-source voltage Vgs of the NMOS transistor Tr1 starts to rise (see section E). Since the output voltage Vo of the DC / DC converter 6 increases again to over voltage limit, LED drive current I _L is increased to until the current value determined by the resistor R1 becomes constant, the control current further described above after a predetermined time has elapsed It increases to the current value (see section E). Since the subsequent operation (section F) is the same as the operation in section C described above, description thereof is omitted.

According to the first embodiment, even when only LED11,11 · · · having the decorative function becomes open fault, LED drive current I _L has a light distribution function having a current value determined by the resistor R1 LED10,10 supplied to ..., then since the LED driving current _{I L} increases with increasing gate-source voltage Vgs of the NMOS transistors Tr1, lighting of LED10,10 ... having a light distribution function maintains Thus, it is possible to improve safety when the vehicle is running.

  Below, the vehicle lamp which concerns on the 2nd Embodiment of this invention is demonstrated.

  In the second embodiment, the lighting control unit 2 of the vehicular lamp 1 according to the first embodiment described above is used for the function of the marker lamp unit 3 for a daytime running lamp or a clearance lamp. This is an example when a dimming function is added.

  The vehicular lamp 30 according to the second embodiment includes a switching unit 40 that controls the emitter voltage of the PNP transistor Tr2 of the lighting maintenance circuit 9 by on / off control, and the switching unit 40 and the control unit 8 include Except for the point that the DC dimming signal Sd is sent out, it is the same as in the first embodiment described above, so the description is omitted. The DC dimming signal Sd is a pulse signal, and is a signal in which a high level signal and a low level signal are repeatedly transmitted at a predetermined cycle.

  The switching unit 40 includes an NPN transistor Tr4 and resistors R11 to R13. The collector of the NPN transistor Tr4 is connected to the emitter of the PNP transistor Tr2 via the resistor R4.

By the way, if it is set as the structure which does not provide the switching part 40, when the marker lamp unit 3 is used for a clearance lamp by DC light control, since LED drive current _IL will decrease compared with the thing for a daytime running lamp, resistance R4 voltage drop is reduced. Therefore, there is a possibility that the second light source 5 is erroneously determined as an open abnormality, the PNP transistor Tr2 is turned on, and the NMOS transistor Tr1 is also turned on.

  Therefore, in the second embodiment, the PNP transistor Tr2 is not turned on and the NMOS transistor Tr1 is not turned on even when the marker lamp unit 3 is used for a clearance lamp by DC dimming.

  Below, operation | movement of the lighting control unit 32 in the vehicle lamp 30 is demonstrated.

  The DC dimming signal Sd is sent to the control unit 8 and the switching unit 40 when the marker lamp unit 3 is used for a daytime running lamp, and is low when it is used for a clearance lamp. The level DC dimming signal Sd is sent to the control unit 8 and the switching unit 40.

  Accordingly, when the clearance lamp is used, the NPN transistor Tr4 is turned off, the voltage at the resistor R4 is not zero, and the PNP transistor Tr2 is not turned on. This is because the resistor R11 is inserted in series with the resistor R4 and the NPN transistor Tr4 is turned off to cause a voltage drop in the resistor R4. Since the PNP transistor Tr2 is not turned on, the NMOS transistor Tr1 is not turned on, and the second light source 5 is kept on.

  As described above, according to the second embodiment, even when the marker lamp unit 3 is used for a clearance lamp by DC dimming, the second light source 5 is not erroneously determined to be open and the first light source 5 is not erroneously determined. The light source 4 and the second light source 5 can be kept on.

  The vehicular lamp according to the third embodiment of the present invention will be described below.

  In the third embodiment, the PWM for performing the function of the marker lamp unit 3 for a daytime running lamp or for a clearance lamp in the lighting control unit 2 of the vehicular lamp 1 according to the first embodiment described above. This is an example when a dimming function is added.

  As shown in FIG. 5, the lighting control unit 52 is the same as that in the first embodiment except that the PWM dimming signal Sc is sent to the control unit 8, and thus the description thereof is omitted.

  Below, the operation | movement of the lighting control unit 52 in the vehicle lamp 50 is demonstrated with reference to FIG. FIG. 6 is a time chart for explaining the operation of the lighting control unit 52. The example of FIG. 6 is an example in which the high-level and low-level PWM dimming signals Sc are intermittently transmitted at a predetermined cycle, and the marker lamp unit 3 is used for a clearance lamp by PWM dimming. . In FIG. 6, a section G indicates a section in which the LEDs 11, 11,... Having the decoration function are normal, and a section H indicates a section in which the LEDs 11, 11,. In the example of FIG. 6, the LEDs 11, 11,. The time t2 is the time in one cycle of the PWM dimming signal Sc, and the time t3 is the time during which the high level signal is output in one cycle of the PWM dimming signal Sc (hereinafter referred to as “high level period”). is there.

PWM dimming signal Sc at the high level is inputted to the control unit 8, when powered on battery, DC / output voltage Vo of the DC converter 6 is raised to a predetermined voltage, LED drive current I _L based on the output voltage Vo Are supplied to the LEDs 10, 10... Via the shunt resistor R _SH and the LEDs 10, 10. LED10,10 LED drive current _{I L} supplied to ... are also supplied to LED11,11 ... via the intermediate output terminal 23,24, LED11,11 ··· also turned (see section G) .

When PWM dimming signal Sc having a low level is input to the control unit 8, the output voltage Vo of the DC / DC converter 6 becomes zero, LED drive current _{I L} does not flow. The voltage at the resistor R4 becomes zero, the PNP transistor Tr2 is turned on, and the NPN transistor Tr3 is turned off. When the NPN transistor Tr3 is turned off, the NMOS transistor Tr1 starts an on operation. A voltage from the control voltage Vcc is applied to the capacitor C through the resistor R3 and charged.

  During the time determined by the time constant of the resistor R3 and the capacitor C, the gate source voltage Vgs of the NMOS transistor Tr1 gradually increases. Before the gate-source voltage Vgs rises to the on-voltage, the high level PWM dimming signal Sc is input again to the control unit 8, the PNP transistor Tr2 is turned off, and the NPN transistor Tr3 is turned on. When the NPN transistor Tr3 is turned on, the NMOS transistor Tr1 starts to turn off. In this way, the dimming control of the marker lamp unit 3 is performed by intermittently sending the PWM dimming signal Sc to the control unit 8 as described above.

  In order to prevent the low-level PWM dimming signal Sc from being sent and the LEDs 11, 11,... The period t2 is preferably set to be sufficiently shorter than the time determined by the time constant of the resistor R3 and the capacitor C (see sections G and H). With this setting, the NMOS transistor Tr1 is not turned on even though the LEDs 11, 11,... Are normal.

  The time determined by the time constant of the resistor R8 and the capacitor C is preferably set to be sufficiently shorter than the period t2 of the PWM dimming signal Sc. With this setting, the discharge of the capacitor C ends during the high level period of the PWM dimming signal Sc, and the gate source voltage Vgs of the NMOS transistor Tr1 becomes zero, so that the LEDs 11, 11,. However, the NMOS transistor Tr1 is not turned on, and the LEDs 11, 11,...

Next, when the LEDs 10, 10,... Are normal but the LEDs 11, 11,... Become open abnormal, no voltage is generated in the resistor R4, so the PNP transistor Tr2 is turned on and the NPN is turned on. The transistor Tr3 is turned off, and the NMOS transistor Tr1 starts an on operation. Gradually increases the gate-source voltage Vgs of the NMOS transistor Tr1, LED drive current _{I L} is increased until the current value determined by the resistor R1 (see section H), LED10,10 lighting of ... it is maintained. After that, the high-level and low-level PWM dimming signals Sc are repeatedly transmitted, the gate-source voltage Vgs of the NMOS transistor Tr1 further rises, and after a predetermined time has elapsed, the NMOS transistor Tr1 is turned on and the LEDs 10, 10,. Maintained (see section H).

  According to the third embodiment, in the vehicular lamp having the PWM dimming function for controlling the dimming of the LED having the light distribution function and the LED having the decoration function, only the LED having the decoration function is an open abnormality. Even in this case, it is possible to maintain the lighting of the LED having the light distribution function and to improve the safety when the vehicle is running.

  Each of the above-described embodiments 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.

1 is a schematic front view of a vehicular lamp according to the present invention. It is the figure which showed the structure of the vehicle lamp which concerns on the 1st Embodiment of this invention. FIG. 6 is a time chart for explaining the operation of the lighting control unit 2. It is the figure which showed the structure of the vehicle lamp which concerns on the 2nd Embodiment of this invention. It is the figure which showed the structure of the vehicle lamp which concerns on the 3rd Embodiment of this invention. 5 is a time chart for explaining the operation of the lighting control unit 52. FIG.

DESCRIPTION OF SYMBOLS 1, 30, 50 ... Vehicle lamp, 3 ... Mark light unit, 6 ... DC / DC converter, 9 ... Lighting maintenance circuit, 10, 11 ... LED

Claims (4)

A light source unit including a first semiconductor light source having a light distribution function and a second semiconductor light source connected in series to the first semiconductor light source and having a decoration function;
A current supply unit for supplying a light source driving current to the light source unit;
A lighting maintenance unit comprising a lighting maintenance switch connected to the first semiconductor light source and the second semiconductor light source, and controlling the light source driving current;
When the first semiconductor light source is abnormal and turned off, the second semiconductor light source is turned off, and when the second semiconductor light source is abnormal and turned off, the first semiconductor light source is kept on. The vehicle lamp is characterized in that the lighting maintenance switch is controlled. The vehicular lamp according to claim 1, wherein a resistor having a predetermined resistance value is disposed between the first semiconductor light source and the second semiconductor light source. The lighting maintenance switch is an NMOS transistor that is turned on when the second semiconductor light source becomes abnormal,
When the NMOS transistor is turned on, the light source driving current flows to the ground through the resistor,
The vehicular lamp according to claim 2, wherein the current value of the light source driving current increases as the on-voltage of the NMOS transistor increases. 4. The vehicular lamp according to claim 1, wherein the light source unit is a daytime running lamp that is turned on in a time zone other than nighttime to exhibit a sign function.

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