Illumination – Illuminated scale or dial
Reexamination Certificate
1999-06-30
2001-05-01
Husar, Stephen (Department: 2875)
Illumination
Illuminated scale or dial
C362S029000, C362S030000, C116S286000, C116SDIG003
Reexamination Certificate
active
06224221
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to rotatable knobs suitable for use with such electric and/or electronic appliances as radios, air conditioners, and the like, particularly in motor vehicles.
BACKGROUND OF THE INVENTION
Illuminated rotatable knobs are disclosed in DE 35 35 881 C2 which describes an illumination apparatus formed from several light conductors and in which the position of the rotatable knob is indicated by corresponding illumination of a scale. This apparatus was developed especially for installation in a motor vehicle. However, a loss of light is incurred by the twisting of the light conductors while using the rotatable knob. Further, the lighting arrangement is very complex in its design.
DE 197 12 294.9 of Preh-Werke GmbH & Co. KG (the assignee of the present invention), published on Oct. 1, 1998, discloses a rotatable knob of a rotary potentiometer comprising a light-transmitting body. A light entry surface is designed in the rotational center thereof, ahead of which a light source is placed. In this case, the light-transmitting body is bounded in its peripheral area with a transparent housing part. This transparent housing part carries a scale visible from the outside. A transparent, light-conducting annulus with a path of light such that a total reflection surface is created, by which the path of the light beams is diverted, is placed between the peripheral area of the light-transmitting body of the rotatable knob and the scale. Again, in this case, experience shows that only a weak illumination of the scale is achieved.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a generic rotatable knob having improved scale illumination. It is another object of the present invention to provide a simplified and improved rotatable knob design that is suitable for mass production.
These and other objects are achieved with a rotatable knob of a control apparatus with electric and/or electronic components and an illuminating arrangement. The knob assembly comprises a light source positioned before a first light-transmitting body situated within the rotatable knob and possessing a light entry surface arranged in the rotational center thereof and terminating with its peripheral portion within a transparent housing part that includes an externally visible scale.
In accordance with this invention, the transparent housing part of the rotatable knob contains a second light-transmitting body fixed in the housing. This second light-transmitting body is disposed between the scale and a peripheral area of the first light-transmitting body. This second light-transmitting body comprises a total reflection surface in its light path, which total reflection surface comprises an outer face forming an envelope of a conic or cup-shaped frustum on which segment-shaped 90° prisms are arranged. The conic or cup-shaped frustum may lie within an angle adjusted with respect to a given light output beam from the second light-transmitting body.
In accordance with a preferred feature of the present invention, the first light-transmitting body may comprise a light output area which effects a light output beam in a direction of a translucent zone with a pointer mark in the rotatable knob.
In another preferred embodiment, the first light-transmitting body and the second light-transmitting body may contain light-diffusing particles.
REFERENCES:
patent: 1566069 (1925-12-01), Buchholz et al.
patent: 2999148 (1961-09-01), Kay
patent: 4215647 (1980-08-01), Fukasawa
patent: 4646206 (1987-02-01), Bauer et al.
patent: 5697689 (1997-12-01), Levine et al.
patent: 21 38 660 (1973-03-01), None
patent: 35 35 881 C2 (1987-04-01), None
patent: 40 22 515 A1 (1992-01-01), None
patent: 197 12 294 A1 (1998-10-01), None
Birch & Stewart Kolasch & Birch, LLP
Husar Stephen
Preh-Werke GmbH & Co. KG
Ward John Anthony
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