Illumination – Illuminated scale or dial – Edge illuminated modifier or light rod/pipe
Reexamination Certificate
2000-01-10
2001-08-21
Husar, Stephen (Department: 2875)
Illumination
Illuminated scale or dial
Edge illuminated modifier or light rod/pipe
C362S023000, C362S029000, C362S030000, C362S499000
Reexamination Certificate
active
06276809
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application relates to and claims priority from Japanese Patent Application No. 11-4664 filed on Jan. 11, 1999, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to meters, and particularly to a meter having a dial plate illuminated from back by a light source and a light transmitting plate. The present invention is suitably applied to a meter disposed on an instrumental panel of a vehicle.
2. Related Art
JP-A-9-21655 discloses an illumination structure for a meter used as a speedometer of a vehicle. In the meter, a light transmitting plate is layered at a rear side of a dial plate, and plural light sources are disposed below the light transmitting plate. Light from the light sources is introduced into the light transmitting plate, and is reflected by the light transmitting plate toward the dial plate. As a result, translucent indication marks and graduations formed on the dial plate are illuminated from back. Light from the light sources is also introduced into a light transmitting pointer disposed on the dial plate, and illuminates the pointer. The light sources are disposed around a shaft of the pointer, and the light transmitting plate has a shaft hole through which the shaft of the pointer passes. Light from the light sources is introduced into the light transmitting plate from the shaft hole.
However, since the light transmitting plate around the shaft hole is formed flat, incidence efficiency of light from the light sources into the light transmitting plate is poor. Especially, when the light sources are light-emitting diodes (LEDs), a large number of the LEDs may need to be used to increase amount of light introduced into the light transmitting plate, because the LED is generally smaller in size and emission area than a lamp. As a result, the number of the light sources may be increased, thereby increasing manufacturing cost of the meter.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a meter having a dial plate sufficiently illuminated by a minimum light source.
According to the present invention, a meter has a dial plate, a pointer, a drive unit from which a shaft of the pointer protrudes, a light transmitting plate disposed at a rear side of the dial plate and a light source for emitting light. The light transmitting plate has a shaft hole into which the shaft is inserted to be engaged with the pointer, and a convex portion disposed in the vicinity of the shaft hole, and formed into a substantially conical shape protruding toward a rear side of the light transmitting plate. The light source is disposed to face the convex portion.
As a result, when the light source emits light, light enters the light transmitting plate from the convex portion at a relatively large incidence angle. Therefore, even when the light source is a single small light-emitting diode, a sufficient amount of light is introduced into the light transmitting plate, and the dial plate is sufficiently illuminated.
Preferably, the pointer is made of a light transmitting material, and the light transmitting plate has a first light reflecting portion formed around the shaft hole to protrude toward the pointer for reflecting light toward a base portion of the pointer. As a result, light reflected by the light reflecting portion is introduced into the pointer, and the pointer is sufficiently illuminated.
REFERENCES:
patent: 4323951 (1982-04-01), Pasco
patent: 4404522 (1983-09-01), Pucciarello
patent: 5915822 (1999-06-01), Ogura et al.
patent: 4121248 (1991-06-01), None
patent: 4433150 (1994-09-01), None
patent: 2506009 (1982-05-01), None
patent: 09-21655 (1997-01-01), None
patent: 09-287981 (1997-11-01), None
Journal Of Nippondenso Technical Disclosure 58-113 (published Mar. 15, 1988).
Denso Corp.
Husar Stephen
Law Office of David G. Posz
Negron Ismael
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