JPH05162582A - Lighting control unit of vehicle lamp body - Google Patents

Abstract

PURPOSE:To provide a lighting control unit capable of preventing a rush current from flowing at the ON of a switch, and improving the life of a lamp body. CONSTITUTION:In a lighting control unit in which a lamp body 11 is connected to a power supply 13 so that a current is supplied from the power supply 13 to the lamp body 11 to light the lamp body at the ON of a switch 15, a switch element 12 the allowable pass current of which is changed according to the magnitude of an inputted drive signal is interposed between the lamp body 11 and the power source 12, and the magnitude of the drive signal to be outputted to the switch element 12 is controlled according to the elapsed time from the ON of the switch 15 to keep the allowable pass current of the switch element 12 at a determined value smaller than a general value until a determined time T passes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle lighting control device, and more particularly to a lighting control device for reducing inrush current when a switch is turned on.

[0002]

2. Description of the Related Art As a conventional vehicle lighting control device, for example, a device described in Japanese Patent Laid-Open No. 63-90457 is known. In this lighting control device, a headlamp is provided between the battery and a relay contact that responds to the switch, and the lighting is turned on when the relay contact is closed and turned off when the relay contact is opened.

[0003]

However, in the above-described conventional lighting control device, since current flows through the headlamp when the relay contact is closed by the switch operation,
When the temperature of the valve filament is low and the electric resistance is low, there is a problem that a large rush current flows during the period until the temperature of the valve filament rises when the relay contact is closed, which adversely affects the durability of the filament. The present invention has been made in view of the above problems, and an object of the present invention is to provide a lighting control device capable of reducing a current flowing through a filament at the time of lighting and to improve durability.

[0004]

In order to achieve the above object, the present invention relates to lighting of a vehicle lamp body in which a lamp body is connected to a power source, and when the switch is turned on, power is supplied from the power source to the lamp body for lighting. In the control device, a switch element that changes according to the magnitude of the drive signal that the allowable passing current is input is interposed between the lamp body and the power supply, and the magnitude of the drive signal output to this switch element is switched on. The allowable passing current of the switch element is maintained at a predetermined value smaller than the normal value by controlling according to the elapsed time from the time of turning on and until the predetermined time elapses.

[0005]

In the vehicle lighting control device of the present invention, when the switch is turned on, that is, the magnitude of the drive signal is controlled according to the elapsed time from the start of energization of the valve filament, the switch is turned on. After that, the allowable passing current of the switch element decreases until a predetermined time elapses. Therefore, the energizing current to the lamp body is regulated so as to be smaller than the normal value, and it is possible to prevent the energizing of the excessive current, that is, the occurrence of the inrush current.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a lighting control device for a vehicle lamp according to an embodiment of the present invention. FIG. 1 is a circuit block diagram,
2 is a timing chart for explaining the operation, FIG.
Is a field effect transistor (FE
T) characteristic diagram of gate-source voltage and drain current,
FIG. 4 is a characteristic diagram of drain-source voltage vs. drain current of the same FET.

In FIG. 1, reference numeral 11 denotes a headlight (lamp body) having a bulb, and as is well known, a pair of left and right headlamps 11 are arranged at the front part of the vehicle body. The headlamp 11 has a well-known bulb, one end of which is connected to the + terminal of the battery 13 and the other end of which is connected to the field effect transistor (switch element) 12. The negative terminal of the battery 13 is grounded by body earth or the like.

The field effect transistor (FET) 12 is
An enhancement-type MOS-FET is used, the drain is connected to the headlamp 11, the source is grounded, and the gate is connected to the drive voltage control circuit 13. As is well known, in the FET 12, the drain current I _D is defined by the gate-source voltage V _GS (see FIG. 3), and the drain current I _D is gate-irrespective of the drain-source voltage V _DS.
It saturates at a value corresponding to the source-to-source voltage V _GS (see FIG. 4).

The drive voltage control circuit 14 comprises a microcomputer, a booster circuit, a gate drive circuit, etc., and is connected to the lamp switch 15. The lamp switch 15 is composed of a well-known switch that can be manually operated by the driver, and outputs a high level signal to the drive voltage control circuit 14 in the ON operation state (see FIG. 2a). The drive voltage control circuit 14 has a timer function, and as shown in FIG. 2, when a high level signal is input from the lamp switch 15, a relatively low voltage (5 V in the embodiment) for a predetermined period T from the time of input. Is applied to the gate of the FET 12 to limit the current value to a low value, and after the lapse of the predetermined period T, a higher voltage (12V, the same) is applied to increase the current value.

Needless to say, the specific numerical values in the embodiments are merely examples, and the specific numerical values are appropriately selected according to the FET to be used and the headlamp. Further, although a headlight is exemplified as the lamp body, it can be applied to a lamp body such as a position lamp.

In this embodiment, when the driver turns on the lamp switch 15, a high level signal is input to the drive voltage control circuit 14 and the drive voltage control circuit 14 causes the FET 12 to operate.
Voltage is applied to the gate of. Here, as shown in FIG. 2, the drive voltage control circuit 14 applies a relatively low voltage to the gate of the FET 12 for a predetermined time T from when the lamp switch 15 is turned on, and after the time T has elapsed, Apply a high voltage. Therefore, even when the temperature of the filament of the bulb of the headlight 11 is low and the electric resistance value is small, the current flowing through the filament when the switch is turned on can be reduced, and the occurrence of inrush current can be prevented. Then, after the lapse of the predetermined time T, a normal current for obtaining sufficient light emission energy is supplied to obtain the required brightness.

That is, the FET 12 has the structure shown in FIGS.
The gate-source voltage V _GS defines the maximum value of the drain current I _D. Therefore,
Even if the temperature of the bulb filament of the headlight 11 is low and the resistance is small, the output voltage of the drive voltage control circuit 14 is kept at a low voltage for a predetermined time after the switch 15 is turned on, so that the energizing current to the bulb filament is suppressed. As a result, a rush current at the time of turning on can be prevented, and thereafter, a current having a normal value is passed to secure sufficient emission energy.

[0013]

As described above, according to the lighting control device for a vehicle lamp according to the present invention, a current flowing through the lamp during a predetermined time from when the switch is turned on, that is, when energization is started. Can be regulated to a small value, so that inrush current can be prevented from occurring even when the filament temperature is low.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a vehicle lamp lighting control device according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the lighting control device.

FIG. 3 is a characteristic diagram of FET gate-source voltage V _GS vs. drain current I _D

FIG. 4 is a drain-source voltage V _DS vs. drain current I _D characteristic diagram of the FET.

[Explanation of symbols]

11 ... Headlight, 12 ... FET (switch element), 13 ... Battery, 14 ... Drive voltage control circuit, 15 ... Switch.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Hirakawa 1-4-1 Chuo, Wako, Saitama Prefecture

Claims (1)

[Claims] 1. A lighting control device for a vehicle lighting body, wherein a lighting body is connected to a power source, and when the switch is turned on, power is supplied from the power source to the lighting body and the lighting control device for the vehicle lighting body is allowed to pass between the lighting body and the power source. A switch element that changes according to the magnitude of the drive signal to which the current is input is provided, and the magnitude of the drive signal output to this switch element is controlled according to the elapsed time from when the switch is turned on Until then, the lighting control device for a vehicle lighting body is characterized in that the allowable passing current of the switch element is maintained at a predetermined value smaller than a normal value.