JP2009150851A - Illuminating device of vehicle instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating device of vehicle instrument capable of inhibiting a heat generation rise of a resistor, while making mounting space of circuit board small by connecting the resistor linked to a light source in common. <P>SOLUTION: This device includes a plurality of light sources 1 which are connected to a power supply side at one side of the light sources 1, a limiting resistor 2 which is formed between the light sources 1 and the power supply and is connected with the plurality of light sources 1 in common, a voltage detection means 3 which detects the voltage supplied from the power supply, and a control means 4 in which a duty ratio is established based on the voltage value, and a PWM drive is carried out so that the plurality of light sources 1 may light alternatively based on the duty ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting device for a vehicle instrument, and is suitable, for example, as a lighting device for a vehicle instrument that PWM-drives an illumination light source in the instrument.

Some conventional lighting devices for vehicle meters use a transistor to control a plurality of light sources to be turned on / off. Such an illuminating device needs to be provided with a plurality of resistors corresponding to each light source, and a large mounting space for the circuit board must be ensured. Therefore, it is desired to share the resistors. .
JP 2003-188415 A

  However, in these illumination devices, since a higher voltage for lighting a plurality of light sources is supplied to the resistor, heat generation of the resistor is increased. In particular, in a lighting device for a vehicle meter, since the supply voltage from the battery power supply changes depending on the use state, when this supply voltage is high, a heat countermeasure such as a heat dissipation structure is required separately. was there.

  Accordingly, an object of the present invention is made by paying attention to the above-described problems, and by sharing the resistor connected to the light source, the mounting space of the circuit board can be reduced, and the resistor An object of the present invention is to provide an illumination device for a vehicle instrument capable of suppressing an increase in heat generation.

  As described in claim 1, the lighting device for a vehicle instrument according to the present invention is provided between a plurality of light sources, one of which is connected to the power source side, and between the light source and the power source, and is common to the plurality of light sources. A connected resistor, voltage detecting means for detecting a voltage supplied from the power source, a duty ratio is set based on the voltage value, and the plurality of light sources are alternately turned on based on the duty ratio And a control means for PWM driving.

  Further, as described in claim 2, in the lighting device for a vehicle meter according to claim 1, the control means is based on duty ratio data corresponding to each voltage value stored in the storage unit. A drive signal for PWM driving the plurality of light sources is generated and output.

  The present invention relates to an illumination device for a vehicle instrument that drives a plurality of light sources, and by sharing a resistor connected to the light source, the mounting space of the circuit board can be reduced and an increase in heat generation of the resistor can be suppressed. It becomes an illuminating device of a vehicle meter capable of.

  Hereinafter, as an embodiment of the present invention, a case where it is mounted in a vehicle instrument provided on an instrument panel of a vehicle and applied to an indicator such as a door opening / closing display will be described as an example with reference to the accompanying drawings. Although not shown in detail, this vehicle meter is composed of a composite meter that displays vehicle information such as vehicle travel speed, engine speed, remaining fuel amount, total travel distance, various warning lights, etc. in addition to these displays. .

  FIG. 1 shows an illuminating device according to an embodiment of the present invention, which mainly comprises a light source 1, a limiting resistor (resistor) 2, a voltage detection means 3, and a control means 4. .

  The light source 1 can be applied with a plurality of LEDs, one of which is connected to the power supply side. In this case, the light source 1 illuminates an alarm mounted on the vehicle meter, and one of the two LEDs is connected to the vehicle via the limiting resistor 2. Connected to a power source such as a battery, and the other is connected to the control means 4. In this case, the light source 1 is provided so that an indicator for displaying the open state of the left and right doors can be turned on.

  The limiting resistor 2 is provided so as to be commonly connected to the plurality of light sources 1 between the light source 1 and the power source. The limiting resistor 2 is selected to have a resistance value that emits light with a desired light emission luminance in consideration of the voltage supplied from the power supply, the specifications and light emission characteristics of the light source 1, the control from the control means 4, and the like.

  The voltage detection unit 3 detects a voltage from a power source supplied to the light source 1 and the limiting resistor 2 and outputs a detection signal corresponding to the voltage value to the control unit 4.

  The control means 4 can be a microcomputer, is connected to a CAN (Controller Area Network) communication cable, an ignition switch (not shown), etc., and inputs a detection signal from the voltage detection means 3, various vehicle information, etc. In response to this signal, a drive signal for controlling each light source 1 is generated and output to each light source 1. The control means 4 includes a CPU for performing arithmetic processing based on various information, a readable / rewritable RAM for temporarily storing arithmetic processing results and the like in the CPU, and a ROM for storing control programs and control data. A bus for exchanging various information, control signals, clock signals, latch signals, and the like with a driver IC that generates a drive signal based on the calculation by the calculation process and outputs the drive signal to the light source 1 And an input / output interface connected thereto.

  Further, the control means 4 stores the optimum duty ratio of the drive signal with respect to the power supply voltage value stored in advance in the storage section as table data, and sets the duty ratio based on the detection signal from the voltage detection means 3. A drive signal is generated based on this duty ratio, and the light source 1 is driven. For example, when both the left and right doors of the vehicle are open, PWM (pulse width modulation) driving is performed so that the two light sources 1 are alternately lit. Note that the control unit 4 shortens the lighting time of the light source 1 when the power supply voltage becomes larger than usual with a change in the power supply voltage based on the table data stored in the storage unit. A drive signal having such a pulse waveform is generated. Therefore, since the voltage supplied to the limiting resistor 2 is intermittently thinned out, it is possible to suppress an increase in heat generation of the limiting resistor 2 due to a voltage change of the power source.

  Such a lighting device for a vehicle instrument includes a plurality of light sources 1 connected to the power source side, a limiting resistor 2 provided between the light source 1 and the power source, and connected in common to the plurality of light sources 1, and a power source. Voltage detecting means 3 for detecting a voltage supplied from the control circuit, and a control means 4 for setting a duty ratio based on the voltage value and performing PWM driving so that a plurality of light sources 1 are alternately lit based on the duty ratio; , Provided.

  Therefore, by sharing the limiting resistor 2 connected to the light source 1, the mounting space for the circuit board can be reduced, and the lighting device for the vehicle instrument can suppress the increase in heat generated by the limiting resistor 2.

  Further, the control means 4 generates and outputs a drive signal for PWM driving the plurality of light sources 1 based on the duty ratio data corresponding to each voltage value stored in the storage unit. By a simple process, the lighting device for the vehicle meter can suppress the rise in heat generation of the limiting resistor 2.

  In addition, although the illumination device for a vehicle instrument of the present invention has been described as an example in the configuration of the above-described embodiment, the present invention is not limited to this, and the configuration of the present invention is not limited thereto. It goes without saying that various improvements and design changes can be made without departing from the scope of the invention. For example, the control unit 4 may generate an optimal drive signal by a predetermined calculation instead of the table data stored in the storage unit. Further, for example, it may be applied to a door indicator displayed on a vehicle meter or a plurality of warning lights, and the same effects as those of the above-described embodiment can be obtained. Further, it can also be applied as a backlight source of liquid crystal for displaying in a plurality of colors.

The figure which shows the structure of embodiment of this invention.

Explanation of symbols

1 light source 2 limiting resistor 3 voltage detection means 4 control means

Claims (2)

A plurality of light sources, one of which is connected to the power supply side;
A resistor provided between the light source and the power source and connected in common with the plurality of light sources;
Voltage detecting means for detecting a voltage supplied from the power source;
A control means for setting a duty ratio based on the voltage value and performing PWM driving so that the plurality of light sources are alternately turned on based on the duty ratio;
A lighting device for a vehicle instrument, comprising: The control means generates and outputs a drive signal for PWM driving the plurality of light sources based on duty ratio data corresponding to each voltage value stored in a storage unit. The lighting device for a vehicle instrument according to claim 1.

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