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Publication numberUS2770712 A
Publication typeGrant
Publication dateNov 13, 1956
Filing dateJan 9, 1952
Priority dateFeb 12, 1951
Also published asDE944739C
Publication numberUS 2770712 A, US 2770712A, US-A-2770712, US2770712 A, US2770712A
InventorsDros Aris
Original AssigneeHartford Nat Bank & Trust Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Illuminated dial plate
US 2770712 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Nov. 13, 1956 DRQS YILLUMINATED DIAL PLATE Filed Jan. 9, 1952 INVENTQR ARIS DROS .& l) A J AG ENT ILLUMINATED DIAL PLATE Application January 9, 1952, Serial No. 265,683 r 1 Claims priority, application Netherlands February 12, 1951 2 Claims. (Cl. 240 2.1

This invention relates to improvements in dials having a dial plate of transparent material which areparticularly useful in radio receivers.

Use is frequently made, particularly in radio receivers, of dial plates of transparent material, illuminated by one or more incandescent lamps, the light of which falls through one of the edges in the plate in which it is propagated by total reflection.

Although initially the dial plates were always made of glass, there is an increasing use of dial plates of transparent plastic material, such, for example, as polymethacrylate.

Plastic dial plates, however, often give rise to difliculties due to the heat produced by the dial lamp, which may result in weakening and, after some time, dim-ness of the plastic material. Previously, this has been an o'bjection to the use of particular plastics having definite advantages, for example, polystyrene, the price of which is relatively low.

The invention has for its object to obviate these difiiculties, which are in general inherent with the use of dial plates of a material having little resistance to heat. This is eifected by providing a connecting piece between the incandescent lamp and the dial plate, this piece being made of a transparent material which has greater resistance to heat than the material of the dial plate.

The difliculties described above will be explained more fully with reference to the drawings in which:

Figure 1 shows the front view of a radio receiver according to the invent-ion.

Figure 2 is a perspective view of the invention from the rear side of the dial, and

Figure 3 shows in section another embodiment of the invent-ion.

The receiver shown in Fig. 1 comprises a front wall which comprises, as usual, a frame 1 having a board provided behind the aperture, in which an aperture 3 for the loudspeaker is provided and covered by a cloth. In front of this cloth provision is made for a dial plate 15 in suitable grooves of the frame 1, a pointer 7 being adapted to move behind this plate. In the connecting piece 17 provision is made for a recess 9 and an illuminating lamp III, which is arranged in a manner such that its light falls laterally on the connecting piece 17 and emerges at the markings of the station dial, so that these marks are distinctly illuminated.

With the use of dial plates of poorly heat-resistant material, for example plastic, in the device described above difiiculties are experienced .due to the heat produced by the lamp 11. Since most clear plastics are thermoplastic, i. e. they weaken under the action of heat, undue deformations and even often dimness of the material may occur about the lamp and over the lamp, hindering the transition of the light into the dial. This is undesirable from an aesthetic point of view. If, in order to avoid this etfect, the radius of the semi-circular recess 9 and hence the spacing between the lamp and the dial plate is chosen to be greater, the quantity of light nited States Patent 2,770,712 Patented Nov. 13, 1956 falling into the dial-plate is considerably reduced. Use may be made of plastics having a slightly greater heat resistance, such for example, as polymethacrylate, but they are materially more costly than plastics having low weakening temperatures, such as for example, polystyrene.

Fig. 2 illustrates, viewed from the rear side of the dial, howthe major part of the dial can be made of inexpensive plastic according to the invention. In this case, a trapezoidal connecting piece 17 of transparent sheet material is arranged between the vertical dial plate 15, made for example, of polystyrene, and the incandescent lamp 11, at right angles to the plate'1 5. The transparent sheet material in piece 17 has a higher weakening point than polystyrene and can be for example, polymethacrylate or glass. The incandescent lamp 11 is housed in a recess at the short parallel edge of the trapezoidal (horizontal) connecting piece 17 and the long parallel edge loosely engages the lower edge of the plate 15 or is secured thereto with the use of transparent adhesive.

Rays emanating approximately horizontally from the lamp 11 are collected by the connecting plate 17 and propagated to the lower edge of the dial plate 15. The rays fall on the rear side in a horizontal direction into the plate 15; however, on the front side, at the lower edge, the plate 15 has a facet, i. e. a slanting surface 19, which is at an angle of approximately 45 to the rear side of the plate and which reflects the horizontal incident inside of the plate approximately in a vertical direction.

As may be seen from the figure, the plate 15 is insulated from the heat produced by the incandescent lamp 11. In the arrangement described above, the cooling of the incandescent lamp is particularly favorable, since a vertical flow of air can freely brush past the lamp. In contradistinction to apparatus of the kind known, structural advantage is obtained by the present invention since the dial occupies little space and since the plate 17 extends primarily along the bottom of the cabinet. The trapezoidal intermediate piece ensures furthermore a uniform distribution of the light in the plate 15.

Furthermore, as an alternative, the plate 17 can be made of two plates of this kind and may be arranged in line with the plate 15.

The intermediate piece 17 may have a particular color or differently colored parts, so that a color effect may be obtained in a colorless dial plate.

Fig. 3 shows, in an axial sectional view, a second embodiment of the intermediate piece 21, which is, in this case, primarily rod-shaped; one end thereof may be secured in a fitting circular aperture in the dial plate 23. This is possible since the material of the plate 23 weakens at a lower temperature than that of the rod 21. At the free end, the rod has a cup-shaped cavity 24, in which the incandescent lamp 11 is housed. At the other end secured in the plate 23, the rod has a re-entrant profile 25 of such a shape that primarily axially incident light rays are projected into the plate 23 in radial directions. This construction is particularly suitable for dial plates, with which the incandescent lamp is arranged approximately opposite the center of the dial plate.

What I claim is:

l. A dial for use in radio receivers comprising an incandescent lamp, a transparent dial plate composed of a thermoplastic resin material which will be deformed or discolored when positioned adjacent to said lamp, said dial plate having a bottom marginal edge which slants angularly upwards, and a transparent connecting piece arranged between said lamp and said dial plate and angularly thereto, said piece being adapted to transmit light from said lamp to said dial plate through said bottom marginal edge and said piece being composed of a thermoplastic resin material exhibiting a value of resistance to heat at which said piece is not substantially deformed or discolored when adjacent said lamp.

2. A dial for use in radio receivers comprising an incandescent lamp, a transparent dial plate composed of a thermoplastic resin material which will be deformed or discolored when positioned adjacent to said lamp, said dial plate having a bottom marginal edge which slants angularly upwards, and a transparent connecting piece in the form of a trapezoidal plate arranged between said lamp and said dial plate and angularly thereto, said piece being adapted to transmit light from said lamp to said dial plate through said bottom marginal edge, said piece being composed of a thermoplastic resin material ex hibiting a value of resistance to heat at which said piece is not substantially deformed or discolored when adjacent said lamp and having a recess in the shorter parallel edge in which is located said incandescent lamp, the longer parallel side of said connecting piece engaging said dial plate, and the air heated by said lamp being adapted to escape in a substantially vertical direction without contacting said connecting piece.

References Cited in the file of this patent UNITED STATES PATENTS 1,714,242 Del Riccio May 21, 1929 2,071,284 Hy1and Feb. 16, 1937 2,150,836 Lamb Mar. 14, 1939 2,413,848 Simpson Ian. 7, 1947 2,560,117 Mallary July 10, 1951 2,611,018 Thorp Sept. 16, 1952 FOREIGN PATENTS 595,003 Great Britain Nov. 25, 1947 OTHER REFERENCES Proceedings of the I. R. E., December 1945, page 829, Table VIII.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1714242 *Apr 19, 1927May 21, 1929Paramount Famous Lasky CorpReflector arc
US2071284 *Oct 23, 1935Feb 16, 1937Bendix Radio CorpIndicating device
US2150836 *Feb 27, 1937Mar 14, 1939Weston Electrical Instr CorpElectrical measuring instrument
US2413848 *Feb 2, 1944Jan 7, 1947Simpson RayIlluminated instrument
US2560117 *Jan 31, 1947Jul 10, 1951Robert W MallarySign
US2611018 *Jun 28, 1950Sep 16, 1952Westinghouse Brake & SignalMimic diagram panel
GB595003A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2854509 *Feb 12, 1953Sep 30, 1958Alden Products CoFacsimile optical scanning apparatus
US2868960 *Feb 7, 1956Jan 13, 1959Arthur V AppelInstrument dial illuminator
US3148834 *Nov 22, 1961Sep 15, 1964Sperry Rand CorpIllumination system
US3248554 *Dec 13, 1961Apr 26, 1966Sperry Rand CorpUniform intensity illumination system
US3761704 *Jan 6, 1972Sep 25, 1973Matusushita Electric Ind Co LtDial illuminating device
US4026635 *Oct 7, 1975May 31, 1977Ab TeleplanIndicator for displaying text or symbols on small surfaces
US4085436 *Oct 14, 1976Apr 18, 1978Allen WeissRing light converter for electronic flash units
US4447118 *Sep 21, 1981May 8, 1984The Boeing CompanyOptical information transfer system
US4564286 *Jun 9, 1983Jan 14, 1986Xerox CorporationIllumination device
US5255162 *May 6, 1992Oct 19, 1993Pioneer Electric CorporationLighting device for a grille of a car stereo
US6932499 *Jun 29, 1999Aug 23, 2005Canon Kabushiki KaishaLight conductive member, illuminating device having the same, and information processing apparatus having the illuminating device
US7566138 *Mar 3, 2006Jul 28, 2009Sumitomo Wiring Systems, Ltd.Light guiding body and lighting apparatus having the same
US20060203463 *Mar 3, 2006Sep 14, 2006Sumitomo Wiring Systems, Ltd.Light guiding body and lighting apparatus having the same
DE1173267B *Aug 14, 1961Jul 2, 1964M K Juchheim ThermometerfabrikVorrichtung zum lichtelektrischen Betaetigen von Grenzwertkontakten und zum Beleuchten der Anzeigemittel bei Zeigereinbauinstrumenten
Classifications
U.S. Classification362/23.15, 385/31, 362/23.1
International ClassificationH03J1/04, H03J1/00, G09F13/18, H01K1/00, H01K1/50
Cooperative ClassificationH01K1/50, H03J1/044, G09F13/18
European ClassificationG09F13/18, H03J1/04C, H01K1/50