Electric lamp and discharge devices: systems – Special application – Vehicle
Reexamination Certificate
2000-11-28
2001-12-11
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Special application
Vehicle
C315S178000, C315S224000
Reexamination Certificate
active
06329755
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light adjustment device for a vehicle used to control illumination of the display panel, operating panel, or the like, of a vehicle.
2. Description of the Related Art
In a vehicle, illumination of various meters on the display panel and knobs on the operating panel, or the like, is performed by means of lamps, LEDs, and the like. A conventional light adjustment device for controlling illumination of these is constituted such that the amount of light emitted by the lamps or LEDs is adjusted by changing the output voltage of a control circuit by operation of a variable resistor.
A prior art example is described below with reference to
FIG. 11
to FIG.
13
.
FIG. 11
is a circuit diagram of a conventional light adjusting device for a vehicle. Reference numeral
1
represents a terminal for connection to a power source, such as a battery, reference numeral
2
represents a lamp for illuminating an indicator
3
, such as shown in
FIG. 2
, and reference numeral
4
represents an LED for illuminating meters
5
, such as the speedometer and fuel gauge, and the like, as shown in FIG.
2
. An anti-surge diode
6
and a current-limiting fixed resistance
7
are connected to the LED
4
. Reference numeral
8
denotes a control circuit generating a constant voltage waveform and reference numeral
9
indicates a rotationally operated variable resistor which is connected to the control circuit
8
. A current control transistor
10
is connected between the control circuit
8
and the lamp
2
and LED
4
. Reference numeral
11
in
FIG. 2
indicates an operating spindle
11
of the variable resistor
9
; by rotating this operating spindle
11
, the angle of the variable resistor
9
is changed. The variable resistor
9
exhibits resistance characteristics R
10
as shown in FIG.
12
. As can be seen, the resistance value is changed linearly in proportion to the operating angle of the variable resistor
9
.
In this prior art light adjustment device for a vehicle, light adjustment is performed by rotating the variable resistor
9
, whereby the output voltage from the control circuit
8
changes and the current flowing through the transistor
10
is altered accordingly, hence causing the intensity of illumination of the lamp
2
and LED
4
to change and therefore causing the brightness of illumination of the indicators
3
and the meters
5
on the display panel to vary.
FIG. 13
is a plot of illumination intensity (%) versus voltage showing the illumination characteristics of the lamp
2
and the LED
4
according to the prior art. As shown, the illumination characteristics L
10
of the lamp
2
which illuminates the indicators
3
are expressed in a curve, whereas the illumination characteristics L
20
of the LED
4
which illuminates the meters
5
are expressed in a straight line. Also, it can be seen that the LED
4
has a greater illumination intensity.
In the conventional light adjustment device for a vehicle, the light adjustment is performed by the variable resistor
9
simultaneously changing the respective intensities of illumination of the lamp
2
and LED
4
having such different characteristics. Since the variable resistor
9
has resistance value characteristics which are expressed in a straight line R
10
as shown in
FIG. 12
, when the variable resistor
9
is rotated at a given angle whereby a given voltage is applied to both of the lamp
2
and the LED
4
, the intensities of illumination of the lamp
2
and LED
4
at this given voltage will be different. As a result, a disparity is produced in the brightness of the indicators
3
which are illuminated by the lamp
2
and the meters
5
which are illuminated by the LED
4
, and consequently the display will be difficult to view properly.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a light adjustment device for a vehicle capable of achieving uniform adjustment of respective intensities of illumination of a lamp and LED having differing illumination characteristics. In order to achieve the aforementioned object, the light adjustment device for a vehicle according to the present invention comprises a lamp, an LED, a control circuit which is connected to said lamp and outputs a predetermined voltage to said lamp, a first variable resistor for changing said voltage output from said control circuit, thereby adjusting illumination of said lamp, and a second variable resistor, having resistance value characteristics that are different from resistance value characteristics of said first variable resistor, for adjusting illumination of said LED.
According to the present invention, either one of the first variable resistor or the second variable resistor has resistance value characteristics that are expressed by a straight line in a plot of resistance value versus operating angle of the variable resistor, while the other has resistance characteristics expressed by a curve. Illumination of the lamp and the LED are respectively controlled by these first and second variable resistors having mutually different resistance value characteristics. It is therefore possible to achieve uniform adjustment of illumination in such a manner that there is no disparity in the degree of illumination of indicators which are illuminated by the lamp and of meters which are illuminated by the LED, on a display panel.
In the invention described above, the first variable resistor and second variable resistor may be operated by the same operating spindle, so that light adjustment of both the lamp and LED can be readily performed.
Furthermore, in the invention described above, it is possible to connect a plurality of fixed resistors to the lamp or LED, instead of at least one of the first variable resistor and the second variable resistor. Thereby, light adjustment can be performed by switching between the plurality of fixed resistors connected to the lamp or LED by operating the operating spindle, and hence the structure of the light adjustment device for a vehicle can be simplified and the device can be made inexpensively.
In the invention described above, if a switch for switching an illumination device other than the lamp and LED adjusted by the first variable resistor and the second variable resistor is provided in the vicinity of the variable resistors, or in an integral fashion with same, then a variety of functional operations can be performed manually by a vehicle occupant in a readily accessible manner. For example, it is possible to provide, in the vicinity of the first and second variable resistors, or in an integral fashion with same, a switch for switching an illumination device disposed in a separate location from the display panel or operating panel for which light adjustment is performed by the first variable resistor and second variable resistor, for example, an interior cabin light, or the like, installed in the upper part of the cabin.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.
REFERENCES:
patent: 4463284 (1984-07-01), Tamura et al.
patent: 61101049 (1986-06-01), None
English Language Abstract of JP 61-101049.
Nakade Yoshiyuki
Shigeyama Shigeo
Takamatsu Masahiro
Umezawa Shigeyoshi
Greenblum & Bernstein P.L.C.
Matsushita Electric - Industrial Co., Ltd.
Vu David
LandOfFree
Light adjustment device for a vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light adjustment device for a vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light adjustment device for a vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2596268