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JP-2026075938-A - Lighting circuits and vehicle lighting fixtures

JP2026075938AJP 2026075938 AJP2026075938 AJP 2026075938AJP-2026075938-A

Abstract

[Problem] To provide a lighting circuit that suppresses variations in the drive current when lighting a light source by changing the drive current. [Solution] The lighting circuit comprises a first drive circuit, a second drive circuit, and first and second power lines that supply power to the first and second drive circuits, wherein the first drive circuit supplies a first drive current of a first value to the light source in a first mode in which a power supply voltage is applied to the first power line, and supplies a first drive current smaller than the first value to the light source in a second mode in which the power supply voltage is applied to the second power line, and the second drive circuit supplies a second drive current of a second value to the light source in the first mode, and stops supplying the second drive current in the second mode. [Selection Diagram] Figure 1

Inventors

  • 中井 啓太

Assignees

  • 株式会社小糸製作所

Dates

Publication Date
20260511
Application Date
20241023

Claims (8)

  1. A lighting circuit comprising a first drive circuit, a second drive circuit, and first and second power lines that supply power to the first and second drive circuits, The first drive circuit is, In the first mode, when the power supply voltage is applied to the first power supply line, a first drive current of a first value is supplied to the light source, and in the second mode, when the power supply voltage is applied to the second power supply line, a first drive current smaller than the first value is supplied to the light source. The second drive circuit is, In the first mode, a second drive current of a second value is supplied to the light source, and in the second mode, the supply of the second drive current is stopped. Lighting circuit.
  2. A lighting circuit according to claim 1, The system includes a first control circuit for controlling the first drive circuit, The first drive circuit is, A variable resistor circuit and A first output circuit that outputs the first drive current corresponding to the resistance value of the variable resistor circuit, Includes, The first control circuit is, In the first mode, the variable resistor circuit is controlled such that the first drive current becomes the first value, and in the second mode, the first drive current becomes smaller than the first value. Lighting circuit.
  3. A lighting circuit according to claim 1, The first drive circuit is, A setting circuit for setting the duty cycle, In the second mode, a first output circuit outputs a first drive current smaller than the first value based on the duty cycle, including, Lighting circuit.
  4. A lighting circuit according to claim 1, The system includes a first control circuit for controlling the first drive circuit, The first drive circuit is, A variable resistor circuit and A setting circuit for setting the duty cycle, In the first mode, a first output circuit outputs a first drive current corresponding to the resistance value of the variable resistor circuit, and in the second mode, a first output circuit outputs a first drive current corresponding to the resistance value of the variable resistor circuit and the duty cycle, Includes, The first control circuit is, In the first mode, the variable resistor circuit is controlled such that the first drive current becomes the first value, and in the second mode, the first drive current becomes smaller than the first value. Lighting circuit.
  5. A lighting circuit according to any one of claims 1 to 4, The second drive circuit is, A second output circuit that outputs the second drive current corresponding to the resistance value of a predetermined resistor, Includes, The second output circuit is, In the first mode, the second drive current of the second value is output, and in the second mode, the supply of the second drive current is stopped. Lighting circuit.
  6. The lighting circuit according to claim 5, When the power supply voltage is applied to the first and second power supply lines, the second control circuit causes the first drive circuit to supply a first drive current of a first value and the second drive circuit to supply a second drive current of a second value. A lighting circuit equipped with the following features.
  7. A lighting circuit according to claim 1, The first and second drive circuits are step-down drive circuits that output a voltage lower than the power supply voltage. Lighting circuit.
  8. Vehicle lighting fixtures, Light source and Equipped with a lighting circuit, The aforementioned lighting circuit is First drive circuit and The second drive circuit and A first power supply line that supplies power to the first drive circuit, A second power supply line that supplies power to the second drive circuit, Includes, The first drive circuit is, In the first mode, when the power supply voltage is applied to the first power supply line, a first drive current of a first value is supplied to the light source, and in the second mode, when the power supply voltage is applied to the second power supply line, a first drive current smaller than the first value is supplied to the light source. The second drive circuit is, In the first mode, a second drive current of a second value is supplied to the light source, and in the second mode, the supply of the second drive current is stopped. Vehicle lighting fixtures.

Description

This invention relates to a lighting circuit and a vehicle lighting device. Some vehicles have lighting fixtures that illuminate a predetermined light source, for example, as a stop lamp or a tail lamp that is dimmer than a stop lamp (for example, Patent Document 1). Patent No. 6867228 This figure shows an example of the configuration of a vehicle lighting fixture 1a.This figure shows an example of the configuration of the first drive circuit 106.This figure shows an example of the configuration of the second drive circuit 109 and the third drive circuit 112.This figure shows an example of the configuration of the first control circuit 116.This figure shows an example of the configuration of the second control circuit 117.This diagram shows an example of the operation of the lighting circuit 10a.This figure shows an example of the configuration of a vehicle lighting fixture 1b.This figure shows an example of the configuration of the first drive circuit 600.This figure shows an example of the configuration of the first control circuit 601.This figure shows an example of the operation of the lighting circuit 10b.This figure shows an example of the configuration of a vehicle lighting fixture 1c.This figure shows an example of the configuration of the first drive circuit 800.This figure shows an example of the operation of the lighting circuit 10c. The following matters become clear from this specification and the accompanying drawings: The following describes preferred embodiments of the present invention with reference to the drawings. Note that identical or equivalent components, members, etc., shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. Furthermore, in this embodiment, "connection" refers to a state of electrical connection unless otherwise specified. Therefore, "connection" includes cases where two components are connected not only by wiring, but also, for example, through a resistor. == <<Configuration of vehicle lighting fixture 1a>> Figure 1 shows an example of the configuration of the vehicle lighting fixture 1a of this embodiment. The vehicle lighting fixture 1a includes switches SW1 and SW2, a lighting circuit 10a, and a light source 20. The light source 20 is illuminated by a drive current Iout supplied from the lighting circuit 10a, which is the sum of drive currents Iout1, Iout2, and Iout3. In this embodiment, the light source 20 is installed at the rear end of the vehicle body and illuminates as a stop lamp or a tail lamp that is dimmer than a stop lamp. The light source 20 is equipped with multiple (for example, three) light-emitting elements (e.g., light-emitting diodes (LEDs)) 30-32. However, the light-emitting elements are not limited to LEDs; other semiconductor light-emitting elements such as laser diodes (LDs) or organic EL elements may also be used. Furthermore, as will be explained in detail later, when the light source 20 is illuminated as a stop lamp, the lighting circuit 10a supplies a drive current Iout with a predetermined current value I0 to the light source 20. On the other hand, when the light source 20 is illuminated as a tail lamp, the lighting circuit 10a supplies a drive current Iout with a predetermined current value I1 (for example, a current value of 1/8 of the predetermined current value I0) to the light source 20. As a result, the stop lamp illuminates brighter than the tail lamp. <<Lighting circuit 10a>> The lighting circuit 10a is applied to the vehicle light fixture 1a and is a circuit that controls the lighting and extinguishing of the light source 20 of the vehicle light fixture 1a. A power supply voltage Vbat (hereinafter also simply referred to as voltage Vbat) of, for example, 24V from the vehicle battery is applied to the power supply line L1 of the lighting circuit 10a via switch SW1. A voltage Vbat is also applied to the power supply line L2 of the lighting circuit 10a from the vehicle battery via switch SW2. Power supply lines L1 and L2 each supply power to the first drive circuit 106, the second drive circuit 109, and the third drive circuit 112, respectively. The voltage of power supply line L1 is denoted as voltage VL1, and the voltage of power supply line L2 is denoted as voltage VL2. Power supply line L1 corresponds to the "first power supply line," and power supply line L2 corresponds to the "second power supply line." Furthermore, for convenience, the voltages VL1 and VL2 are notated differently, but since the on-resistance of switches SW1 and SW2 is sufficiently small, the voltage levels of VL1 and VL2 when switches SW1 and SW2 are turned on are the same as the voltage level of voltage Vbat. The lighting circuit 10a then supplies a drive current Iout based on the on/off status of switches SW1 and SW2, and turns the light source 20 on or off as a stop lamp or tail lamp. <<Configuration of the lighting circuit 10a>> The lighting circuit 10a includes capacitors 100, 104, 107,