Light-controlling device used for vehicle

Details Light-controlling device used for vehicle Light-controlling device used for vehicle

2002-10-04

2003-09-16

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Special application

Vehicle

C315S178000, C315S159000, C315S224000, C307S010800

Reexamination Certificate

active

06621224

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a light-controlling device used for controlling illumination of an indicator or an operating panel in a vehicle.
BACKGROUND OF THE INVENTION
A conventional light-controlling device illuminates an indicator or an operating panel using an incandescent lamp or a light emitting diode (LED). Operating a variable resistor changes an electric output of a controlling circuit, so that illumination of the incandescent lamp or the LED is controlled.
The conventional light-controlling device is described hereinafter with reference to
FIGS. 8-10
.
FIG. 8
shows a circuit diagram of a conventional light-controlling device used for a vehicle.
FIG. 9
shows an outward appearance of a dashboard in a vehicle. As shown in
FIGS. 8 and 9
, connecting terminal
1
of a power supply e.g., battery, is coupled with incandescent lamp
2
for illuminating indicator
3
and the like. Connecting terminal
1
is also coupled with diode
6
for suppressing surge. In addition, diode
6
, fixed resistance
7
for controlling an electric current, and light emitting diode (LED)
4
for illuminating meter
5
such as a speed meter or a fuel meter are connected in series.
Controlling circuit
8
, which generates voltage waveforms, is coupled with variable resistor
9
which is operated by rotating. Transistor
10
for controlling an electric current is coupled with controlling circuit
8
, incandescent lamp
2
and LED
4
.
FIG. 10
is a graph showing a characteristic of a resistance for an operating angle. A resistance value rate for an operating angle varies linearly as shown in characteristic R
1
of FIG.
10
.
When operating section
11
of variable resistor
9
rotates, an operating angle changes, thereby changing a resistance value rate. Then an output voltage from controlling circuit
8
changes, and an electric current through transistor
10
is controlled. As a result, illumination of incandescent lamp
2
and LED
4
change, and brightness of indicator
3
and meter
5
on a dashboard change.
However, when incandescent lamp
2
differs from LED
4
in characteristic, a minimum voltage of illuminating lamp
2
differs from that of LED
4
at predetermined illumination. In that case, when operating section
11
rotates for turning off, indicator
3
illuminated by lamp
2
and meter
5
illuminated by LED
4
are not turned off simultaneously. As a result, an operator feels strange.
SUMMARY OF THE INVENTION
The present invention aims to provide a light-controlling device, which is used for a vehicle and includes the following elements:
(a) a controlling circuit coupled with a plurality of light-emitting sections, which have minimum voltages different from each other at predetermined illumination,
(b) a variable resistor for changing illumination of the plurality of light-emitting sections by changing an electric output of the controlling circuit,
where when the illumination of the plurality of light-emitting sections decreases to the predetermined illumination using the variable resistor, the controlling circuit turns the plurality of light-emitting sections off simultaneously based on a signal from a detecting section which is linked with the variable resistor.


REFERENCES:
patent: 4463284 (1984-07-01), Tamura et al.
patent: 4494851 (1985-01-01), Maida et al.
patent: 6320330 (2001-11-01), Haavisto et al.
patent: 6329755 (2001-12-01), Nakade et al.

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