JP7131085B2 - vehicle lamp - Google Patents

Description

The present invention relates to a vehicle lamp.

In recent years, vehicular lamps have been provided that also function as daytime running lamps in addition to functioning as turn lamps and clearance lamps. A PWM-controlled power supply circuit is used to supply the required power to each of the turn lamps, clearance lamps, and daytime running lamps (see, for example, Patent Documents 1 and 2).

JP 2015-230423 A JP 2016-048988 A

However, in the prior arts such as those described in Patent Documents 1 and 2, lighting circuits are mounted for each of the turn lamps, clearance lamps, and daytime running lamps, and switching circuits for switching these lamps are separately required. Furthermore, in order to satisfy legal requirements, when any one of the turn lamps, clearance lamps, and daytime running lamps is turned on, the other lamps must be turned off, so a dedicated timer IC or microcomputer is used separately. there is Therefore, a large-capacity element, a dedicated circuit, and a redundant high-performance circuit are required, resulting in high cost and an increase in the number of parts. Therefore, with the conventional techniques as described in Patent Documents 1 and 2, it is not possible to achieve cost reduction and miniaturization while satisfying legal requirements.

The present disclosure has been made in view of such circumstances, and aims to achieve cost reduction and miniaturization while satisfying regulatory requirements.

A vehicle lamp according to one aspect of the present disclosure includes a lighting circuit for supplying an input current, a first light emitting element group, and a second light emitting element group provided in parallel with the first light emitting element group. and a load switching circuit for switching the supply destination of the input current supplied from the lighting circuit to either the first group of light emitting elements or the second group of light emitting elements, wherein the load switching circuit comprises a PWM control unit for outputting a PWM control signal for controlling the lighting circuit; and one of the first light emitting element group and the second light emitting element group based on the PWM control signal output from the PWM control unit. A delay circuit that delays switching timing to one side , and a switching control unit that determines a delay time for delaying the switching timing based on an output voltage output from the delay circuit and a lighting input signal , The lighting input signal is a signal corresponding to at least one of a daytime running lamp, a turn lamp, and a clearance lamp .

Further, in the vehicle lamp according to one aspect of the present disclosure, the delay circuit includes a time constant setting unit that sets a time constant that determines the switching timing; and a time constant adjustment unit that adjusts the determined time constant.

According to one aspect of the present disclosure, cost reduction and miniaturization can be realized while satisfying regulatory requirements.

1 is a circuit diagram of a vehicle lamp according to an embodiment to which the present disclosure is applied; FIG. 3 is a block diagram showing the functional configuration of the load switching circuit 3 according to the embodiment to which the present disclosure is applied; FIG. 2 is a diagram showing a circuit configuration example of a delay circuit 32 according to an embodiment to which the present disclosure is applied; FIG. 4 is a time chart illustrating an example of setting a delay time when switching from DTRL lighting to TrL lighting according to an embodiment to which the present disclosure is applied; 7 is a time chart illustrating an example of setting a delay time after switching from DTRL lighting to TrL lighting according to an embodiment to which the present disclosure is applied; 4 is a time chart illustrating an example of setting a delay time when switching from CLL lighting to TrL lighting according to an embodiment to which the present disclosure is applied;

Hereinafter, embodiments of a vehicle lamp to which the present disclosure is applied will be described in detail based on the drawings. Note that the present disclosure is not limited by this embodiment.

Embodiment 1.
(Outline configuration)
FIG. 1 is a circuit diagram of a vehicle lamp according to an embodiment to which the present disclosure is applied. A vehicle lamp is, for example, a headlamp, and headlamp units are mounted on both left and right ends of a front portion of a vehicle. The vehicle lamp includes a lighting circuit 1, a load switching circuit 3, a first light emitting element group LDm, and a second light emitting element group LDn. The lighting circuit 1 supplies an input current to either one of the first light emitting element group LDm and the second light emitting element group LDn. The first light emitting element group LDm includes light emitting elements LD_A1 to LD_Am. Each of the light emitting elements LD_A1 to LD_Am is connected in series. Each of the light emitting elements LD_A1 to LD_Am is composed of, for example, an LED (Light Emitting Diode). The second light emitting element group LDn is provided in parallel with the first light emitting element group LDm. The second light emitting element group LDn includes light emitting elements LD_B1 to LD_Bn. Each of the light emitting elements LD_B1 to LD_Bn are connected in series. The load switching circuit 3 switches the supply destination of the input current supplied from the lighting circuit 1 to either the first light emitting element group LDm or the second light emitting element group LDn.

The vehicle lamp controls the amount of light by changing the lighting interval and lighting current of the first light emitting element group LDm and the second light emitting element group LDn according to a combination of lighting input signals input to the load switching circuit 3 . The lighting input signal is a signal corresponding to at least one of a daytime running lamp, a turn lamp, and a clearance lamp. The lighting circuit 1 controls the light intensity of the first light emitting element group LDm and the second light emitting element group LDn based on the current setting signal and the ON/OFF control signal input from the load switching circuit 3 as a daytime running lamp and a turn signal. Control to correspond to ramps and clearance ramps. In the vehicle lamp, the load switching circuit 3 outputs a PWM control signal used for dimming the first light emitting element group LDm and the second light emitting element group LDn, the first light emitting element group LDm and the second light emitting element group LDn. A PWM control signal for controlling switching timing to switch to one of the groups LDn is shared. In the following description, it is assumed that the first light emitting element group LDm has the function of a daytime running lamp or a clearance lamp, and the second light emitting element group LDn has the function of a turn lamp. , but not limited to.

The lighting circuit 1 is supplied with the input voltage Vin applied to the capacitor C1. The input voltage Vin is supplied from a battery (not shown). The lighting circuit 1 includes a booster circuit 11 , a current detection circuit 12 and a DCDC control circuit 13 . The booster circuit 11 includes a coil L1, a capacitor C2, a capacitor C3, a Zener diode ZD1, a switching element Q1 and a resistor R1. The coil L1 has one end connected to the input side and the other end connected to the anode side of the Zener diode ZD1. One end of a capacitor C2 is connected to the cathode side of the Zener diode ZD1. The other end of capacitor C2 is connected to ground. A capacitor C3 is connected in parallel with the Zener diode ZD1. The switching element Q1 is an N-channel MOSFET. The switching element Q1 has a drain side connected to the anode side of the Zener diode ZD1, a source side connected to the ground via the resistor R1, and a gate side connected to the DCDC control circuit 13 . The current detection circuit 12 is composed of a shunt resistor R_SH. The DCDC control circuit 13 controls the switching frequency of the switching element Q1 according to the detection result of the current detection circuit 12. FIG. The DCDC control circuit 13 controls the switching element Q1 to either the ON state or the OFF state according to the switching frequency, thereby realizing the boosting function of the boosting circuit 11 .

A switching element Q2 is provided between the lighting circuit 1 and the first light emitting element group LDm. The switching element Q2 is an N-channel MOSFET, and has a drain side connected to the output side of the lighting circuit 1, a source side connected to the first light emitting element group LDm, and a gate side connected to the load switching circuit 3. A series circuit of resistors R2 and R3 is connected in parallel with the first light emitting element group LDm, and a voltage V_m obtained by dividing the resistors R2 and R3 is input to the load switching circuit 3 .

A switching element Q3 is provided between the lighting circuit 1 and the second light emitting element group LDn. The switching element Q3 is an N-channel MOSFET, and has a drain side connected to the output side of the lighting circuit 1, a source side connected to the second light emitting element group LDn, and a gate side connected to the load switching circuit 3. A series circuit of resistors R4 and R5 is connected in parallel with the second light emitting element group LDn, and a voltage V_n obtained by dividing the resistors R4 and R5 is input to the load switching circuit 3 .

(circuit configuration)
FIG. 2 is a block diagram showing the functional configuration of the load switching circuit 3 according to the embodiment to which the present disclosure is applied. Based on the lighting input signal, the voltage V_m, and the voltage V_n, the load switching circuit 3 switches the current setting signal, the ON/OFF control signal, the first light emitting element group LDm connection signal, or the second light emitting element group LDn connection signal. Output a signal. The load switching circuit 3 includes a PWM control section 31 , a delay circuit 32 , a switching control section 33 , a current setting section 34 and a DCDC circuit operation control section 35 . The PWM control section 31 outputs a PWM control signal for controlling the lighting circuit 1 based on one of the voltage V_m and the voltage V_n and a preset duty ratio. The PWM control signal is output to the delay circuit 32 and the DCDC circuit operation control section 35 . The delay circuit 32 delays switching timing for switching to either the first light emitting element group LDm or the second light emitting element group LDn based on the PWM control signal output from the PWM control section 31 . Details of the delay circuit 32 will be described later.

The switching control unit 33 determines a delay time for delaying the switching timing based on the output voltage output from the delay circuit 32 and the lighting input signal. The switching control unit 33 outputs a switching time delay signal to the DCDC circuit operation control unit 35 based on the determined delay time, and controls either the switching element Q2 or the switching element Q3 to the ON state. The switching control unit 33 supplies the first light emitting element group LDm connection signal to the gate side of the switching element Q2 when controlling the switching element Q2 to the ON state. The switching control unit 33 supplies the second light emitting element group LDn connection signal to the gate side of the switching element Q3 when controlling the switching element Q3 to the ON state. Among the lighting input signals, DTRL is a signal corresponding to the daytime running lamp, CLL is a signal corresponding to the clearance lamp, and TrL is a signal corresponding to the turn lamp.

Details will be described later with reference to FIGS. 4 to 6, but when the lighting input signal is DTRL, the switching time delay signal is output when the lighting start time of the first light emitting element group LDm is Td. When TrL, it is output when the second light emitting element group LDn lighting start time is Tb, and when the lighting input signal is CLL, it is output when the second light emitting element group LDn lighting start time is Tf. When the lighting start time of the first light emitting element group LDm is Td, the output voltage of the delay circuit 32 is Vd. When the lighting start time of the second light emitting element group LDn is Tb, the output voltage of the delay circuit 32 is Vb. When the lighting start time of the second light emitting element group LDn is Tf, the output voltage of the delay circuit 32 is Vf. When the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn is Ta, the output voltage of the delay circuit 32 is Va. When the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn is Tc, the output voltage of the delay circuit 32 is Vc. When the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn is Te, the output voltage of the delay circuit 32 is Ve. When the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn is Tg, the output voltage of the delay circuit 32 is Vg.

The DCDC circuit operation control unit 35 outputs an ON/OFF control signal to the DCDC control circuit 13 based on the lighting input signal and the switching time delay signal. When the lighting input signal is DTRL, the DCDC circuit operation control unit 35 lights the first light emitting element group LDm with a constant current, and when the lighting input signal is CLL, the current at DTRL is dimmed by PWM control to perform the first light emission. The element group LDm is turned on. That is, when the lighting input signal is CLL, the DCDC circuit operation control unit 35 performs dimming by adding PWM control to the lighting state by DTRL. The PWM control signal that the PWM control unit 31 outputs to the DCDC circuit operation control unit 35 has, for example, a frequency of 500 Hz and an on-duty value of 5%.

When the lighting input signal is TrL and when the second light emitting element group LDn is to be lit, the legal requirement is to turn off the first light emitting element group LDm which is lit by the lighting input signal DTRL. There is Therefore, when the DCDC circuit operation control unit 35 switches from the circuit configuration including the first light emitting element group LDm lighting as the daytime running lamps to the circuit configuration including the second light emitting element group LDn lighting as the turn lamps. , and the PWM control signals for CLL. When the blinking of the second light emitting element group LDn functioning as turn lamps is completed and the lighting operation is completed, the first light emitting element group LDm which has been lighting as the daytime running lamps is turned on again.

The current setting section 34 outputs a current setting signal corresponding to the lighting input signal to the DCDC control circuit 13 . As a result, an input current corresponding to the lighting input signal is supplied to the first light emitting element group LDm and the second light emitting element group LDn.

FIG. 3 is a diagram showing a circuit configuration example of the delay circuit 32 according to the embodiment to which the present disclosure is applied. The delay circuit 32 includes a time constant adjusting section 321 , a time constant setting section 322 , a delay generating section 323 and a reset section 324 . The time constant setting unit 322 includes a resistor R6 and a capacitor C5 connected in series with the resistor R6, and sets a time constant that determines switching timing. The switching timing is timing for switching to either the first light emitting element group LDm or the second light emitting element group LDn, and the delay time is changed according to the lighting input signal. The time constant adjusting section 321 adjusts the time constant determined by the time constant setting section 322 according to the lighting input signal. The time constant adjustment unit 321 is composed of a switched capacitor consisting of a capacitor C4, a switching element Q8, and a switching element Q9, and is a pseudo-resistance component corresponding to the period for exclusively controlling the ON/OFF of the switching element Q8 and the switching element Q9, It functions as a variable resistance component connected in series with resistor R6. In other words, the time constant can be arbitrarily adjusted by changing the cycle of exclusively controlling the ON/OFF of the switching element Q8 and the switching element Q9 according to the lighting input signal. Control of the ON state and OFF state of the switching element Q8 and the switching element Q9 can be realized by a control circuit (not shown).

The delay generator 323 delays and outputs the PWM control signal. The delay generator 323 includes a capacitor C6, a capacitor C7, an inverter INV1, an inverter INV2, a switching element Q10 and a switching element Q11. The switching element Q10 has one end connected to the output of the time constant setting section 322 and the other end connected to a connection point between one end of the capacitor C6 and the input side of the inverter INV1. The switching element Q11 has one end connected to the output side of the inverter INV1 and the other end connected to a connection point between one end of the capacitor C7 and the input side of the inverter INV2. It should be noted that the switching element Q10 and the switching element Q11 are controlled so as not to be turned on at the same time, although a detailed description thereof will be omitted as it can be easily understood by those skilled in the art. The reset unit 324 resets the internal states of the time constant adjustment unit 321 , the time constant setting unit 322 and the delay generation unit 323 . The reset unit 324 includes switching elements Q4 to Q7, which are N-channel MOSFETs, arranged in parallel. The drain side of the switching element Q4 is connected to one end of the capacitor C4 via the resistor R7. The drain side of the switching element Q5 is connected to one end of the capacitor C5 via the resistor R8. The drain side of switching element Q6 is connected to one end of capacitor C6 via resistor R9. The drain side of switching element Q7 is connected to one end of capacitor C7 via resistor R10. In other words, by controlling the switching elements Q4 to Q7 to the ON state, the potentials of the capacitors C4 to C7 are discharged and the output voltage of the delay circuit 32 is reset.

(circuit operation)
FIG. 4 is a time chart illustrating a setting example of a delay time when switching from DTRL lighting to TrL lighting according to an embodiment to which the present disclosure is applied. When the turn lamp is controlled to be on, the DCDC control circuit 13 stops operating and the output voltage of the delay circuit 32 is reset. The output voltage of the delay circuit 32 begins to rise in response to the PWM control signal, and the output voltage of the delay circuit 32 reaches Va corresponding to Ta, which is the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn. , the supply destination of the input current supplied from the lighting circuit 1 is switched from the first light emitting element group LDm to the second light emitting element group LDn. When the output voltage of the delay circuit 32 reaches Vb corresponding to the lighting start time Tb of the second light emitting element group LDn, the DCDC control circuit 13 is operated.

FIG. 5 is a time chart illustrating a setting example of a delay time after switching from DTRL lighting to TrL lighting according to the embodiment to which the present disclosure is applied. The output voltage of the delay circuit 32 rises according to the PWM control signal, and after exceeding Vb, the turn lamp is controlled to be turned off, the turn lamp blinking is completed, and it is determined that the turn lamp has completed blinking. In this case, until the output voltage of the delay circuit 32 reaches Vc corresponding to Tc, which is the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn, the input current supplied from the lighting circuit 1 is switched from the second light emitting element group LDn to the first light emitting element group LDm. When the output voltage of the delay circuit 32 reaches Vd corresponding to the lighting start time Td of the first light emitting element group LDm, the DCDC control circuit 13 is operated. It should be noted that the turn lamp is in the ON state, the OFF state, or the flashing completion state, and whether or not the flashing completion of the turn lamp is determined is based on the ON/OFF control signal output from the DCDC circuit operation control unit 35. DCDC control circuit 13 can determine.

FIG. 6 is a time chart illustrating a setting example of the delay time when switching from CLL lighting to TrL lighting according to the embodiment to which the present disclosure is applied. Lighting of the clearance lamps and turn lamps is controlled by high-speed switching operation so that the second light emitting element group LDn is turned on while the first light emitting element group LDm is turned off. At this time, the time constant of the delay circuit 32 is also changed. The current set value is also changed while switching the lighting method of the first light emitting element group LDm and the second light emitting element group LDn, which are the loads, to either continuous lighting or PWM control in combination with the lighting input signals. When the turn lamp is turned on while the clearance lamp is on, the output voltage of the delay circuit 32 is Ve corresponding to Te, which is the switching delay time between the first light emitting element group LDm and the second light emitting element group LDn. , the supply destination of the input current supplied from the lighting circuit 1 is switched from the first light emitting element group LDm to the second light emitting element group LDn. When the output voltage of the delay circuit 32 reaches Vf corresponding to the lighting start time Tf of the second light emitting element group LDn, the DCDC control circuit 13 is operated. The destination of the input current supplied from the lighting circuit 1 until the output voltage of the delay circuit 32 reaches Vg corresponding to the switching delay time of the first light emitting element group LDm/second light emitting element group LDn. are switched from the second light emitting element group LDn to the first light emitting element group LDm. Since the turn lamp has a higher light intensity than the clearance lamp, the input current to be input to the second light emitting element group LDn is increased while the second light emitting element group LDn is being lit.

(Effect)
As described above, in the present embodiment, the timing of switching to either the first light emitting element group LDm or the second light emitting element group LDn is delayed based on the PWM control signal. Therefore, it is not necessary to mount the lighting circuit 1 corresponding to each of the turn lamps, clearance lamps and daytime running lamps. is not required. Furthermore, even without a dedicated timer IC or microcomputer, when any one of the turn lamps, clearance lamps, and daytime running lamps is turned on, the other lamps can be turned off, which satisfies legal requirements. Therefore, since an element with a large capacity, a dedicated circuit, and a redundant high-performance circuit are unnecessary, it is possible to avoid high cost and an increase in the number of parts. Therefore, cost reduction and miniaturization can be realized while satisfying legal requirements.

Note that switching to either the first light emitting element group LDm or the second light emitting element group LDn is controlled based on the PWM control signal, so the loss of power conversion efficiency can be reduced. In addition, since the daytime running lamp, the clearance lamp and the turn lamp can be lit by one lighting circuit 1, the space can be saved. Since only one DCDC control circuit 13 is required for one lighting circuit 1, the DCDC control circuit 13 for supplying power for lighting each of the daytime running lamp, the clearance lamp and the turn lamp can be shared. Further, when combining the capacitor C5 and the resistor R6 to create a time constant, by combining the PWM control signal, the electrostatic capacitance of the capacitor C5 and the resistance value of the resistor R6 can be changed more than simply combining the capacitor C5 and the resistor R6. Since it can be kept low, it is not necessary to make the capacitor C5 particularly expensive for temperature compensation. Therefore, it is possible to realize a circuit configuration particularly remarkably at low cost. In addition, the daytime running lamps, clearance lamps and turn lamps can be turned on individually, so that legal requirements can be reliably met.

Further, in the present embodiment, the delay time for delaying the switching timing is determined based on the output voltage output from the delay circuit 32 and the lighting input signal. Therefore, the first light emitting element group LDm and the second light emitting element group LDn can be exclusively controlled with a simple configuration. Therefore, it is possible to realize a low-cost circuit configuration while surely satisfying legal requirements.

Further, in the present embodiment, the time constant that determines the switching timing is adjusted according to the lighting input signal. Therefore, since the switching timing can be determined with a simple configuration, it is possible to significantly realize low cost and miniaturization.

As described above, the vehicle lamp to which the present disclosure is applied has been described based on the embodiment, but the present disclosure is not limited to this, and modifications may be made without departing from the gist of the present disclosure.

For example, the configuration example in which the delay generation unit 323 includes the capacitor C6, the capacitor C7, the inverter INV1, the inverter INV2, the switching element Q10, and the switching element Q11 has been described, but it is not particularly limited to this, and PWM control Any circuit configuration that can delay a signal may be used. Also, although an example in which the time constant adjustment unit 321 is configured by a switched capacitor has been described, the present invention is not particularly limited to this, and any circuit configuration that can adjust the time constant may be used.

Reference Signs List 1 lighting circuit 11 booster circuit 12 current detection circuit 13 DCDC control circuit 3 load switching circuit 31 PWM control unit 32 delay circuit 321 time constant adjustment unit 322 time constant setting unit 323 delay generation unit 324 reset unit 33 switching control unit 34 current setting unit 35 DCDC circuit operation control unit Vin input voltage C1 to C7 capacitor L1 coil R1 to R10 resistor R_SH shunt resistor ZD1 Zener diode INV1, INV2 inverter Q1 to Q11 switching element LDm first light emitting element group, LD_A1 to LD_Am light emitting element LDn second light emitting element group, LD_B1 to LD_Bn light emitting elements V_m, V_n voltage

Claims (2)

a lighting circuit that supplies an input current;
a first light emitting element group;
a second light emitting element group provided in parallel with the first light emitting element group;
a load switching circuit that switches a supply destination of an input current supplied from the lighting circuit to either one of the first light emitting element group and the second light emitting element group;
with
The load switching circuit is
a PWM control unit that outputs a PWM control signal for controlling the lighting circuit;
a delay circuit for delaying switching timing of switching to either one of the first light emitting element group and the second light emitting element group based on a PWM control signal output from the PWM control unit;
a switching control unit that determines a delay time for delaying the switching timing based on the output voltage output from the delay circuit and the lighting input signal;
with
The lighting input signal is
A signal corresponding to at least one of a daytime running lamp, a turn lamp, and a clearance lamp ;
Vehicle lighting. The delay circuit is
a time constant setting unit that sets a time constant that determines the switching timing;
a time constant adjustment unit that adjusts the time constant determined by the time constant setting unit according to the lighting input signal;
comprising
The vehicle lamp according to claim 1 .

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