JP2021002440A - Lighting control device, lighting control method, and vehicular lighting fixture - Google Patents

Abstract

To provide good-response lighting control with simple constitution.SOLUTION: A lighting control device 1 for a light source unit 2 that includes at least a first light source module 21 which has a relatively small electric load and a second light source module 22 which has a relatively large electric load, executes, when a voltage supply circuit supplies voltages to each of the first light source module and second light source module, a first control of turning the voltage supply circuit ON to supply the voltage to the first light source module, a second control of disconnecting a current path of the first light source module and keeping the voltage supply circuit ON, and a third control of connecting a current path of the second light source module and keeping the voltage supply circuit ON.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lighting control technique for a light emitting element, and more particularly to a lighting control technique for a vehicle lamp configured by using the light emitting element.

Conventionally, when pulse dimming a light emitting element such as an LED, lighting control is performed by combining, for example, a step-up circuit and a step-down circuit in consideration of responsiveness (for example, Japanese Patent Application Laid-Open No. 2018-102053). That is, when only the booster circuit is used, it takes a relatively long time to raise the voltage, and it is difficult to turn on the light emitting element sharply. Therefore, the voltage is boosted to a constant voltage by the booster circuit in advance. The responsiveness was ensured by generating a desired voltage with a step-down circuit.

However, in the above-mentioned conventional configuration, since the booster circuit and the step-down circuit are combined, the configuration becomes complicated, and it is difficult to reduce the cost.

Japanese Unexamined Patent Publication No. 2018-102053

One of the specific aspects of the present invention is to provide a lighting control technique capable of performing lighting control with good responsiveness with a simple configuration.

[1] The lighting control device of one aspect according to the present invention (a) controls lighting of a light source unit including at least a first light source module having a relatively small load and a second light source module having a relatively large load. (B) A voltage supply circuit that supplies a voltage generated by boosting to each of the first light source module and the second light source module, and (c) the first light source module and the voltage supply. The first switching element provided in the current path with the circuit, (d) the second switching element provided in the current path between the second light source module and the voltage supply circuit, and (e) the voltage supply circuit. It includes a control unit that controls on / off and controls the on / off of each of the first switching element and the second switching element. (F) The control unit turns the first switching element into an on state. A first control in which the voltage supply circuit is turned on to supply a voltage to the first light source module, and a second control in which the first switching element is turned off and the voltage supply circuit is maintained in the on state. It is a lighting control device that executes a third control that turns on the second switching element and keeps the voltage supply circuit in the on state.
[2] The lighting control device of one aspect according to the present invention is (a) a lighting control device of a light source module including at least a first light source module having a relatively small load and a second light source module having a relatively large load. (B) When the voltage generated by boosting the voltage is supplied to each of the first light source module and the second light source module by the voltage supply circuit, the voltage supply circuit is turned on and the first light source module is turned on. The first control for supplying a voltage to the light source module, the second control for blocking the current path of the first light source module and maintaining the voltage supply circuit in the ON state, and the current path of the second light source module are conductive. It is a lighting control device that executes a third control that keeps the voltage supply circuit in the ON state at the same time.
[3] One aspect of the lighting control method according to the present invention is (a) a lighting control method for a light source module including at least a first light source module having a relatively small load and a second light source module having a relatively large load. (B) When the voltage generated by boosting the voltage is supplied to each of the first light source module and the second light source module by the voltage supply circuit, the voltage supply circuit is turned on and the first light source module is turned on. The first step of supplying a voltage to the light source module, the second step of cutting off the current path of the first light source module and maintaining the voltage supply circuit in the ON state, and conducting the current path of the second light source module are conducted. It is a lighting control method that executes the third step of keeping the voltage supply circuit in the ON state at the same time.
[4] The vehicle lighting fixture according to the present invention is a vehicle lighting fixture provided with the lighting control device according to any one of the above.

In the present specification, "connection" between a certain circuit element and another circuit element means not only the case where these circuit elements are directly connected to each other, but also the case where another circuit element or the like is between these circuit elements. The case of intervening connection is also included.

According to the above configuration, it is possible to perform lighting control with good responsiveness with a simple configuration.

FIG. 1 is a diagram showing a configuration of a vehicle lamp according to an embodiment. 2 (A) to 2 (E) are waveform diagrams for explaining the operation of the lighting control device. 3 (A) to 3 (E) are waveform diagrams for explaining the operation of the lighting control device of the comparative example. 4 (A) to 4 (E) are waveform diagrams for explaining the operation of the lighting control device. 5 (A) to 5 (E) are waveform diagrams for explaining the operation of the lighting control device of the comparative example. 6 (A) to 6 (E) are waveform diagrams for explaining the operation of the lighting control device of the modified example. 7 (A) to 7 (E) are waveform diagrams for explaining the operation of the lighting control device of the modified example. FIG. 8 is a diagram showing a configuration of a vehicle lighting fixture of a modified example. FIG. 9 is a waveform diagram for explaining the operation of the lighting control device according to the modified example in FIG.

FIG. 1 is a diagram showing a configuration of a vehicle lamp according to an embodiment. The illustrated vehicle lamp is configured to include a lighting control device 1 and a light source unit 2 whose lighting is controlled by the lighting control device 1.

The vehicle lighting fixture lights the light source modules 21 and 22 of the light source unit 2 in a time-division manner. The light source module 21 is used as, for example, a low beam lamp (passing lamp), and the light source module 22 is used, for example, as a position lamp (vehicle side lamp).

The light source module 21 is configured by connecting a relatively small number (for example, 3) of light emitting elements in series, and the light source module 22 is configured by connecting a relatively large number (for example, 14) of light emitting elements in series. It is connected and configured. In other words, it can be said that the light source module 21 has a relatively low electrical load and the light source module 22 has a relatively high electrical load. The light source module 21 and the light source module 22 are connected in parallel. The light emitting element included in each of the light source modules 21 and 22 is, for example, an LED, and all have the same specifications. The voltage required to drive the light source module 21 is about 10 V, and the voltage required to drive the light source module 22 is about 47 V. In the present specification, the voltage range required for driving is 2V or more and less than 20V as "relatively low electrical load", and the voltage range required for driving is 20V or more and less than 50V "relatively". "High electrical load".

The lighting control device 1 shown in FIG. 1 includes a booster circuit (voltage supply circuit) 10, a control microcomputer (control unit) 11, switching elements 12, 13, 14 and a resistance element (discharge circuit) 15.

The booster circuit 10 generates a voltage of a desired magnitude by boosting the voltage VB supplied from the battery of the vehicle. As the booster circuit 10, for example, a known booster DC / DC converter can be used. The voltage generated by the booster circuit 10 is supplied to the light source unit 2.

The control microcomputer 11 is for controlling the overall operation of the lighting control device 1, and is configured by using, for example, a microcomputer having a CPU, a ROM, a RAM, or the like. Specifically, the control microcomputer 11 is connected to the booster circuit 10 and performs on / off control of the booster circuit 10, and is connected to the switching elements 12, 13 and 14 to perform on / off control of these.

The switching element 12 is connected in series with the light source module 21, and by opening and closing according to a control signal given from the control microcomputer 11, the conduction / interruption of the current path including the light source module 21 is switched. As the switching element 12, for example, the illustrated field effect transistor can be used.

The switching element 13 is connected in series with the light source module 22, and by opening and closing according to a control signal given from the control microcomputer 11, the conduction / interruption of the current path including the light source module 22 is switched. As the switching element 13, for example, the illustrated field effect transistor can be used.

The switching element 14 is connected in series with the resistance element 15, and by opening and closing according to a control signal given from the control microcomputer 11, the conduction / interruption of the current path including the resistance element 15 is switched. As the switching element 14, for example, the illustrated field effect transistor can be used.

The resistance element 15 is connected in parallel with the light source modules 21 and 22, and is also connected to the booster circuit 10. When the switching element 14 is in the open state, the resistance element 15 is connected to the reference potential (ground potential) terminal and functions as a discharge circuit.

2 (A) to 2 (E) are waveform diagrams for explaining the operation of the lighting control device. Specifically, FIG. 2A is an output voltage waveform of the booster circuit 10, FIG. 2B is an output current waveform of the booster circuit 10, and FIG. 2C is a waveform showing on / off of the booster circuit 10. 2 (D) is a waveform showing on / off (conduction / cutoff) of the switching element 12, and FIG. 2 (E) is a waveform showing on / off (conduction / cutoff) of the switching element 13. Here, the operation when both the light source module 21 used as the low beam lamp and the light source module 22 used as the position lamp are turned on will be described.

At time t1, when the booster circuit 10 changes from the off state to the on state under the control of the control microcomputer 11, and the switching element 12 changes from the off state to the on state, the voltage of the booster circuit 10 starts to rise. Since the light source module 21 corresponding to the switching element 12 has a small number of light emitting elements, the voltage of the booster circuit 10 reaches the set voltage of the light emitting element in a relatively short time (for example, 0.3 ms). When the set voltage is reached at time t2, a current flows through the light source module 21 and each light emitting element lights up.

Here, in order to prevent the lighting delay of the light source module 21, the booster circuit 10 is switched to the on state and the switching element 12 is switched to the on state, for example, 0.1 ms earlier. The gradient of the current during 0.1 ms depends on the light emitting element, but as a whole, the light source module 21 is lit for a long period (for example, 3.5 ms), so that the current accuracy at the time of dimming is not significantly affected.

At time t3, the switching element 12 is switched from the on state to the off state by the control of the control microcomputer 11. As a result, the light source module 21 is turned off. At this time, the control microcomputer 11 keeps the booster circuit 10 in the ON state. As a result, the voltage of the booster circuit 10 further rises.

At time t4, the switching element 13 is switched from the off state to the on state by the control of the control microcomputer 11. At this time, the booster circuit 10 is maintained in the ON state, and the voltage has risen above the set voltage of the light emitting element, so that a current instantly flows through the light source module 22 and each light emitting element is turned on. The period from time t3 to time t4 is set to, for example, 0.6 ms.

After that, at time t5, the switching element 13 is switched from the on state to the off state by the control of the control microcomputer 11. As a result, each light emitting element of the light source module 22 is turned off. The period from time t4 to time t5 is set to, for example, 0.25 ms.

Further, at this time t5, the booster circuit 10 is switched to the off state by the control of the control microcomputer 11. This is to prevent an excessive voltage from being applied when the light source module 21 is turned on in the next cycle to generate a surge current. As described above, the light source module 21, which has a relatively low load, can be quickly raised to the voltage required for driving the light source module 21, and the lighting period is long, so that the accuracy of current control is not affected so much. The circuit 10 can be temporarily turned off. The period from time t5 to time t6 (end of one cycle) is set to, for example, 0.6 ms. Further, the voltage of the booster circuit 10 drops to the lowest value when 0.1 ms has elapsed from the time t5.

By repeating the above operation in the cycle T, both the light source module 21 corresponding to the low beam and the light source module 22 corresponding to the position lamp can be time-divisionally driven by one booster circuit 10.

When the voltage required for the light source module 22 is relatively low, the open circuit voltage of the booster circuit 10 is lowered by the control of the control microcomputer 11, or the switching element 14 is controlled by the discharge circuit composed of the resistance element 15. The open circuit voltage can also be lowered by discharging.

3 (A) to 3 (E) are waveform diagrams for explaining the operation of the lighting control device of the comparative example. The configuration of the lighting control device of the comparative example is the same as that of the embodiment shown in FIG. 1, and the control method thereof is different. In the lighting control device of the comparative example, when the switching element 12 is turned off and the light source module 21 is turned off at time t11, the booster circuit 10 is also turned off, so that the voltage of the booster circuit 10 drops. After that, when the switching element 13 is turned on and the booster circuit 10 is also turned on at time t12, each light emitting element of the light source module 22 lights up in the process of increasing the voltage of the booster circuit 10. Therefore, for example, if the lighting time of the light source module 22 is set according to the required lighting time specification, the emitted light of the light source module 22 becomes dark, and on the other hand, if the lighting time is lengthened, the specification cannot be satisfied. Bring.

4 (A) to 4 (E) are waveform diagrams for explaining the operation of the lighting control device. The details of each waveform are the same as those in FIG. Here, the operation when only the light source module 22 used as the position lamp is turned on will be described.

As shown in the figure, since the light source module 21 is turned off, the switching element 12 is left in the off state (see FIG. 4D). At time t4, the switching element 13 is switched from the off state to the on state by the control of the control microcomputer 11. At this time, in the first cycle, since the voltage of the booster circuit 10 has not risen sufficiently, the current flowing through the light source module 22 also becomes low, and the light emitted from the light source module 22 becomes dark.

After that, at time t5, the switching element 13 is switched from the on state to the off state by the control of the control microcomputer 11. As a result, each light emitting element of the light source module 22 is turned off. At this time, the booster circuit 10 is maintained in the ON state under the control of the control microcomputer 11. As a result, the voltage of the booster circuit 10 gradually rises to the maximum value and is maintained.

In the next second cycle, at time t4', the switching element 13 is switched from the off state to the on state by the control of the control microcomputer 11. At this time, since the voltage of the booster circuit 10 has risen sufficiently, each light emitting element of the light source module 22 lights up with sufficient brightness.

After that, at time t5', the switching element 13 is switched from the on state to the off state by the control of the control microcomputer 11. As a result, each light emitting element of the light source module 22 is turned off. Even at this time, the booster circuit 10 is maintained in the ON state under the control of the control microcomputer 11. As a result, the voltage of the booster circuit 10 rises to the maximum value and is maintained.

By repeating the above operation in the cycle T, the light source module 22 corresponding to the position lamp can be driven with the necessary and sufficient brightness at least in the second and subsequent cycles.

5 (A) to 5 (E) are waveform diagrams for explaining the operation of the lighting control device of the comparative example. The detailed contents of the light source module 22 during operation in this comparative example are the same as those in the comparative example shown in FIG. 3 described above, and the inconveniences are also the same. Therefore, detailed description thereof will be omitted here.

6 (A) to 6 (E) are waveform diagrams for explaining the operation of the lighting control device of the modified example. The details of each waveform are the same as those in FIG. Here, a case where the voltage rise of the booster circuit 10 is limited by a constant value when both the light source module 21 used as the low beam lamp and the light source module 22 used as the position lamp are turned on will be described. Since the overall operation is the same as that shown in FIG. 2, the description thereof will be omitted.

As shown in FIG. 6A, the voltage rise of the booster circuit 10 from the time t3 to the time t4 is limited. The voltage increase may be limited by a control signal from the control microcomputer 11 to the booster circuit 10, or a limit circuit may be provided on each of the current paths of the light source modules 21 and 22. In the figure, as indicated by reference numeral a, the magnitude of the voltage of the booster circuit 10 is set to a value slightly smaller than the maximum voltage of the light source module 22 having a relatively high load. Since it is sufficient to boost only this slight voltage difference when the light source module 22 is lit, it is possible to prevent an overcurrent when the light source module 22 is lit and not to impair the responsiveness.

7 (A) to 7 (E) are waveform diagrams for explaining the operation of the lighting control device of the modified example. The details of each waveform are the same as those in FIG. Here, the operation when only the light source module 22 used as the position lamp is turned on will be described. A case where the control microcomputer 11 performs lighting control using a data table in the case of lighting will be described. Since the overall operation is the same as that shown in FIG. 4, the description thereof will be omitted.

As shown in the figure, since the light source module 21 is turned off, the switching element 12 is left in the off state (see FIG. 7D). At the time t1 of the first cycle, the lever of the vehicle is operated and a signal instructing the lighting of the position lamp is input to the control microcomputer 11. At this time, the control microcomputer 11 controls the booster circuit 10 to the ON state. As a result, the voltage of the booster circuit 10 begins to rise (see FIG. 7A).

At time t4, the switching element 13 is switched from the off state to the on state by the control of the control microcomputer 11. At this time, since the voltage of the booster circuit 10 has risen sufficiently, each light emitting element of the light source module 22 lights up with sufficient brightness.

After that, at time t5, the switching element 13 is switched from the on state to the off state by the control of the control microcomputer 11. As a result, each light emitting element of the light source module 22 is turned off. Even at this time, the booster circuit 10 is maintained in the ON state under the control of the control microcomputer 11. As a result, the voltage of the booster circuit 10 rises to the maximum value and is maintained.

The same control as above is executed in the second and subsequent cycles. In this way, a data table showing a control timetable according to the lighting pattern is prepared in advance and stored in a memory (not shown) of the control microcomputer 11, and control is performed according to the timetable. The light source module 22 can be turned on with sufficient brightness from the first cycle.

FIG. 8 is a diagram showing a configuration of a vehicle lighting fixture of a modified example. The difference from the embodiment shown in FIG. 1 is that the capacitive element (voltage holding circuit) 16 is added, so only the difference will be described. The capacitive element 16 is connected in parallel with the light source modules 21, 22 and the resistance element 15, and is also connected to the booster circuit 10. The other end side of the capacitance element 16 is connected to the reference potential terminal. The capacitive element 16 is, for example, an electrolytic capacitor.

FIG. 9 is a waveform diagram for explaining the operation of the lighting control device according to the modified example in FIG. The details of each waveform are the same as those in FIG. At time t4, the switching element 13 is switched from the off state to the on state and each light emitting element of the light source module 22 is lit, and then at time t5, the switching element 13 is switched from the on state to the off state and each light source of the light source module 22 is emitted. The element turns off. At this time, as indicated by reference numeral b in the figure, the voltage of the booster circuit 10 gradually decreases because the voltage is held by the capacitance element 16. That is, the slope of the discharge is adjusted. As a result, a necessary and sufficient voltage can be obtained even when each light emitting element of the light source module 21 is turned on in the next one cycle, so that the responsiveness is improved.

According to the above-described embodiment and modification, it is possible to obtain a lighting control technique capable of performing lighting control with good responsiveness with a simple configuration.

The present invention is not limited to the contents of the above-described embodiment, and can be variously modified and implemented within the scope of the gist of the present invention. For example, the configuration of the light source module is an example and is not limited to the above contents. Further, the use of each light source module is not limited to the above contents.

Further, in the above-described embodiment, the booster circuit is mentioned as an example of the voltage supply circuit, but the voltage supply circuit is not limited as long as it has a function of boosting the voltage. For example, a buck-boost circuit may be used as the voltage supply circuit. Good.

Further, in the above-described embodiment, the case where two light source modules are controlled to be lit is illustrated, but there may be three or more light source modules. In this case, for example, when the load of the third light source module is relatively small, the same lighting control as the lighting control for the light source module 21 may be performed before or after the lighting control for the light source module 22. Often, when the load of the third light source module is relatively large, the same lighting control as the lighting control for the light source module 22 is performed after the lighting control for the light source module 21 or after the lighting control for the light source module 22. You can do it at the right time. The same applies when the fourth and subsequent light source modules exist.

1: Lighting control device, 2: Light source unit, 10: Booster circuit, 11: Control microcomputer, 12, 13, 14: Switching element, 15: Resistance element, 16: Capacitive element

Claims (8)

A device for controlling the lighting of a light source unit including at least a first light source module having a relatively small load and a second light source module having a relatively large load.
A voltage supply circuit that supplies a voltage generated by boosting to each of the first light source module and the second light source module.
A first switching element provided in the current path between the first light source module and the voltage supply circuit, and
A second switching element provided in the current path between the second light source module and the voltage supply circuit, and
A control unit that controls on / off of the voltage supply circuit and controls on / off of each of the first switching element and the second switching element.
Including
The control unit turns on the first switching element and turns on the voltage supply circuit to supply voltage to the first light source module, and turns off the first switching element. At the same time, the second control for keeping the voltage supply circuit in the ON state and the third control for keeping the voltage supply circuit in the ON state while turning on the second switching element are executed.
Lighting control device. After executing the third control, the control unit executes a fourth control for turning off the second switching element and turning off the voltage supply circuit.
The lighting control device according to claim 1. The control unit periodically repeats a unit period including the first control, the second control, the third control, and the fourth control.
The lighting control device according to claim 2. A voltage holding circuit connected in parallel with each of the first light source module and the second light source module is further included.
The lighting control device according to any one of claims 1 to 3. Further including a discharge circuit connected in parallel with each of the first light source module and the second light source module.
The lighting control device according to any one of claims 1 to 4. A lighting control device for a light source module including at least a first light source module having a relatively small load and a second light source module having a relatively large load.
When supplying the voltage generated by boosting the voltage to each of the first light source module and the second light source module by the voltage supply circuit, the voltage supply circuit is turned on to supply the voltage to the first light source module. The first control for causing the voltage supply circuit to be interrupted, the second control for cutting off the current path of the first light source module and maintaining the voltage supply circuit in the ON state, and the voltage supply circuit for conducting the current path of the second light source module. Executes the third control, which keeps the on state,
Lighting control device. It is a lighting control method of a light source module including at least a first light source module having a relatively small load and a second light source module having a relatively large load.
When the voltage generated by boosting by the voltage supply circuit is supplied to each of the first light source module and the second light source module, the voltage supply circuit is turned on to supply the voltage to the first light source module. The first step, the second step of interrupting the current path of the first light source module and maintaining the voltage supply circuit in the on state, and the current path of the second light source module are conducted and the voltage supply circuit is connected. Perform the third step, which keeps it on,
Lighting control method. A vehicle lamp comprising the lighting control device according to any one of claims 1 to 6.

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