Lighting control circuit for vehicle lighting equipment

• US 20060043901A1
• Filed: 09/01/2005
• Published: 03/02/2006
• Est. Priority Date: 09/02/2004
• Status: Active Grant

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Ito, Masayasu, Takeda, Hitoshi
• Granted Patent: US 7,414,524 B2
• Time in Patent Office: Days
• US Class Current: 315/77
• CPC Class Codes: B60Q 1/28 for indicating front of vehicle
• CPC Class Codes: B60Q 2400/30 Daytime running lights [DRL], e.g. circuits or arrangements therefor
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

A higher voltage out of a battery voltage applied to an ignition voltage terminal or a control voltage applied to a control voltage terminal is supplied to a switching regulator via a diode. Then, a supply of current to an LED in the switching regulator is controlled in compliance with the control voltage while using an input voltage as energy. When a PWM signal is input into a control voltage terminal as the control voltage, transistors are turned off and on, whereby an instruction to turn-on the-LED in a dimmed lighting mode is issued to the switching regulator. Then, a current that is smaller than that supplied in a full lighting mode is supplied to the LED.

Claims

1. A lighting control circuit for vehicle lighting equipment, comprising:

selecting means for selecting a higher voltage from a battery voltage of a vehicle or a control voltage used to control a semiconductor light source;

controlling means for controlling a supply of current to the semiconductor light source in response to the control voltage, while using the voltage selected by the selecting means as an energy; and

deciding means for deciding whether the control voltage corresponds to a voltage used to turn on the semiconductor light source in a dimmed lighting mode;

wherein the controlling means reduces the supply of current to the semiconductor light source rather than a full lighting mode when an affirmative decision result is output from the deciding means.

2. A lighting control circuit for vehicle lighting equipment, according to claim 1, wherein the deciding means includes

average voltage generating means for generating an average voltage by smoothing the control voltage, and

dimmed lighting instructing means for instructing the controlling means to control the semiconductor light source in a dimmed lighting mode when the average voltage generated by the average voltage generating means is less than a predetermined voltage that is lower than the battery voltage.

3. A lighting control circuit for vehicle lighting equipment, according to claim 1, wherein the deciding means includes

average voltage generating means for generating an average voltage by smoothing the control voltage, and

dimmed lighting instructing means for instructing the controlling means to control the semiconductor light source in a dimmed lighting mode when the average voltage generated by the average voltage generating means is at a battery voltage or is higher than a predetermined voltage.

4. A lighting control circuit for vehicle lighting equipment, according to claim 1, further comprising:

turning-off instructing means for instructing the controlling means to turn off the semiconductor light source when it is sensed that the control voltage corresponds to a voltage used to turn off the semiconductor light source.

5. A lighting control circuit for vehicle lighting equipment, according to claim 2, further comprising:

a turning-off instructing means for instructing the controlling means to turn off the semiconductor light source when it is sensed that the control voltage corresponds to a voltage used to turn off the semiconductor light source.

6. The lighting control circuit for vehicle lighting equipment according to claim 3, further comprising:

a turning-off instructing means for instructing the controlling means to turn off the semiconductor light source when it is sensed that the control voltage corresponds to a voltage used to turn off the semiconductor light source.