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Publication numberUS3641390 A
Publication typeGrant
Publication dateFeb 8, 1972
Filing dateJun 5, 1969
Priority dateJul 9, 1968
Also published asCA930870A, CA930870A1, DE1933330A1
Publication numberUS 3641390 A, US 3641390A, US-A-3641390, US3641390 A, US3641390A
InventorsNakamura Tadashi
Original AssigneeIse Electronics Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Solid-state letter display device
US 3641390 A
A plurality of luminous diodes and a driving circuit therefor adapted to cause selected combinations of the luminous diodes to luminesce to display selected letters are formed on the same or different sides of a substrate and the assembly is encapsulated by a transparent molded protective coating. The driving circuit in the form of a diode matrix circuit is fabricated by the integrated circuit technique.
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Description  (OCR text may contain errors)

United States Patent Nakamura 54] SOLID-STATE LETTER DISPLAY DEVICE [72] Inventor:

[73] Assignee:

Tadashi Nakamura, Ise-City, Japan lse Electronics Corporation, lse-City, Japan [22] Filed: Julie 5,1969

[211 App]. No.: 830,706

[30] Foreign Application Priority Data July 9, 1968 Japan ..43/476l9 52 us. c1 ..315/l69, 313/108 .1105 37/00 Field or Search ..307/303; 313/108, 108 1);

1451- 4 Feb. 8, 1972 [56] References Cited UNITED STATES PATENTS 2,951,970 9/1960 Matarese ..315/169 3,308,452 3/1967 Michel et al. ..315/169 x 3,330,983 7/1967 Cusano et a1... ..313/108 3,343,155 9/1967 Pahlavan ..3i5/l69 x 3,354,342 11/1967 Ohntrup 8t al ..3l5/169 x Primary Examiner-Roy Lake Assistant ExaminerLawrence J Dahl Attorney-Chittick, Pfund, Birch, Samuels & Gauthier [57] ABSTRACT A plurality of luminous diodes and a driving circuit therefor adapted to cause selected combinations of the luminous diodes to lurninesce to display selected letters are formed on the same or different sides of a substrate and the assembly is encapsulated by a transparent molded protective coating. The driving circuit in the form of a diode matrix circuit is fabricated by the integrated circuit technique.

1 Claims, 4 Drawing Figures SOLID-STATE LETTER DISPLAY DEVICE I BACKGROUND OF THE INVENTION This invention relates to a novel solid-state letter display device.

Among conventional letter display devices may be mentioned a light spot-type display device employing discharge tube-type display tubes, fluorescent display tubes or groups of small lamps. These prior devices are not advantageous in that the physical dimensions of the devices are large when compared with those of the letter or characters to be displayed or the number of letters to be displayed because all .of these devices utilize vacuum tubes, require relatively high voltage and relatively large power, have poor space factor and require independent driving circuits.

Recently developed electronic circuits require miniaturization of the display device itself, low operating voltage, small driving power and decreased thickness of the device because of the tendency of utilizing integrated circuits and large scale integrated.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a new and improved letter display device which can eliminate disadvantages of the above described types of conventional display devices and can satisfy the requirements of modern display devices.

One of the features of this invention lies in a solid-state letter display device wherein well-known luminous diodes are used as the display elements, the display driving circuit is formed by the technique of the integrated circuit so that these elements are formed on a substrate and are then molded into a unitary structure. Accordingly, the solid-state letter display device embodying this invention is characterized in that it does not utilize any vacuum tube and that it is of small size and thin.

Another feature of this invention lies in a solid-state letter display device wherein luminous diodes and a display driving circuit are formed on a single-semiconductor wafer as an integrated circuit and are then molded into a unitary structure.

Still further feature of this invention is to provide a solidstate letter display device capable of displaying a number of letters.

In accordance with this invention there is provided a solidstate letter display device characterized by comprising a substrate, a plurality of luminous diodes which are formed on the substrate and arranged such that when they are suitably combined they can display any desired letter, a driving circuit for selectively exciting the luminous diodes, said driving circuit being formed on the substrate by the integrated circuit technique and a protective coating encapsulating the substrate, the luminous diodes and the driving circuit. The substrate may be an electric insulator, a metal plate or a semiconductor wafer.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages together with organization and operation of this invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view of a solid'state letter display device or unit embodying the principle of this invention with a portion of the casing broken away;

FIG. 2 is a partial sectional view showing the relation between a substrate and luminous elements;

FIG. 3 shows a diagram of one example of a diode matrix driving circuit employed in this invention and FIG. 4 is a perspective view of a solid-state display device for displaying a plurality of letters.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 illustrating a perspective view, partly broken away, of a novel display unit for displaying digits, reference numeral indicates an insulating substrate of ceramic and the, like on which are formed a group of display elements a through h for constituting digits 0 through 9 inclusive wherein elements g and g are formed electrically integral. These elements are comprised by luminous diodes having PN- 10 junctions. The luminous diode is a solid-state luminous element typically consisting of GaAs, and as is well known in the art luminesces by the injection of charge carriers through the PN-junction by the application of a voltage and the recombination of such charge carriers. According to this invention, a preformed group of luminous diodes a through h is bonded to the substrate 10. As shown in FIG; 1, a driving circuit 20 formed by the integrated circuit technique is also bonded to the substrate. As will be described later in more detail, the

. driving circuit is comprised by a diode matrix circuit adapted to select predetermined combinations of display elements and to cause them to luminesce to form desired digits. One example of such a diode matrix circuit is illustrated in FIG. 3.

The diode matrix circuit shown in FIG.'3 is a so-called erasing system selecting circuit wherein the number of diodes utilized is decreased. In FIG. 3 reference numeral 0 through 9 represent terminals corresponding to respective digits to be displayed and terminals a through h correspond to respective luminous diodes shown in FIG. 1. It is now assumed that after closing a switch S, a wiper W is connected to a terminal corresponding to a digit desired to be displayed, then the digit will be displayed by a selected combination of luminous diodes. Thus for example, digit 3 is assumed to be displayed. Upon connecting the wiper W to terminal 3, diode D, will short circuit element f, diodes D and D element e and diodes D and D elements g and g. As a result, voltage is applied to elements a, b, c, d and h alone so that as can be readily understood from FIG. 1 these elements cooperate to display digit According to this invention the diode matrix circuit is fabricated by a well-known integrated circuit technique which may be either multitip, monolithic or mixed integrated circuit. In this manner, the circuit substrate 20 comprising an integrated circuit is of extremely small size. According to this invention, the circuit substrate 20 is bonded to the substrate 10 either on the front surface thereof as shown in FIG. 1 or on the rear surface. In addition to terminals 0 through 9, the circuit substrate 20 requires two more terminals for the source and ground. Thus there are 12 terminals. In FIG. I these terminals are shown by terminals T. v

As best shown in FIG. 3, it is necessary to connect circuit substrate 20 to respective luminous elements a through h. FIG. 2 is a cross-sectional view to illustrate the manner of deriving out lead wires to respective elements when the circuit substrate 20 is bonded to the rear surface of the substrate 10. More particularly, luminous elements are bonded to the front surface of the substrate and two perforations ll and 12 are provided near the opposite ends of. each luminous element. Grounding lead 30 connected to the lower electrode of the luminous element extends through the perforation 11 while an exciting lead connected to the upper electrode extends through the perforation 12 to a driving circuit.

A protective coating 40 of a resinous material, for example, is molded to encapsulate the assembly,- as shown in FIG. 1. In order to make visible the luminous elements, at least the front portion of the protective coating 40 should be transparent. Thus, FIG. 1 shows a solid-state letter display device or unit embodying this invention.

As can be noted from the foregoing description, the novel letter display device is characterized by having no vacuum tube or filament. In addition, since the luminous elements and mechanical vibrations and shocks. Further, as a driving circuit and luminous diodes are fabricated by the integrated circuit technique it is possible to operate them with low voltage and low power. For this reason the novel display device can be operated directly from an integrated circuit system. If the portion of the protective coating were constructed to act as an optical lens, more easy reading of the displayed letter would be possible. When suitably colored the coating acts as a filter. lnasmuch as the luminous elements utilized in this invention are comprised by luminous diodes, where indium and phosphorus are used in the semiconductor material, the luminous elements will emit red colored, while zinc and cerium provide blue colored. In this manner, letters of different colors can be displayed.

Although in the above embodiment, a plurality of independent luminous elements and an integrated driving circuit were bonded to a common insulating substrate of ceramic or the like, it will be obvious to those skilled in the art that such luminous elements and driving circuit may be formed on a single-semiconductor wafer by the integrated circuit technique. Where a metal plate is utilized as the substrate to act as one of the electrodes of the luminous diodes, not only the construction of the assembly can be simplified but also the efficiency of heat dissipation can be improved.

FIG. 4 shows a perspective view of a modified embodiment of this invention wherein a plurality of display unitsshown in FIG. 1 are arranged in side by side relationship to simultaneously display a number of letters or numerals of several orders of magnitude. 7

Although the invention has been shown and described in terms of preferred embodiments thereof numerous changes and modifications may occur to one skilled in the art within I the scope of this invention as defined in the appended claim.

What is claimed is:

1. A self-contained solid-state character decoder display device comprising:

a thin support substrate having a rectangular area generally the size of a character space occupied in a display;

a plurality of luminous PN-junction diode display elements supported on said substrate in the form of a character raster with power and ground electrical leads respectively from each side of said PN-junction projecting through said substrate; I

a set of plug connection terminals extending from one edge of said substrate, one terminal for each character to be selected and in addition power and ground terminals;

a unitary diode matrix decoder circuit supported on said substrate outside the area occupied by said character raster, said circuit having:

a first set of leads connected respectively to said power leads of said display elements and a second set of character selection leads with a diode connected selection circuit from each character selection lead of said second'set to a predetermined combination of leads of said first set,

circuit connections from said ground terminal to said ground leads of all of said display elements, and

circuit connections from said power terminal through respective resistors to each lead of said first set; and an encapsulating shell for said substrate providing a transparent area over the area occupied by said display elements and having said terminals projecting therefrom.

Patent Citations
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US2951970 *Mar 25, 1957Sep 6, 1960Sylvania Electric ProdElectroluminescent device
US3308452 *Dec 24, 1962Mar 7, 1967IbmHigh speed electro-optical semiconductor display apparatus
US3330983 *Nov 9, 1964Jul 11, 1967Gen ElectricHeterojunction electroluminescent devices
US3343155 *Jan 6, 1964Sep 19, 1967Pahlavan Marcel ADisplay apparatus
US3354342 *Feb 24, 1964Nov 21, 1967Burroughs CorpSolid state sub-miniature display apparatus
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3715636 *Jan 3, 1972Feb 6, 1973Gen ElectricSilicon carbide lamp mounted on a ceramic of poor thermal conductivity
US3781852 *Nov 21, 1972Dec 25, 1973Bowmar Instrument CorpCalculator display circuit
US3800177 *Dec 20, 1971Mar 26, 1974Motorola IncIntegrated light emitting diode display device with housing
US3827043 *Dec 6, 1972Jul 30, 1974Suwa Seikosha KkDisplay device for numeric characters
US3855500 *Jun 27, 1973Dec 17, 1974Sony CorpGaseous glow-discharge indicator system
US3889147 *Sep 30, 1974Jun 10, 1975Litton Systems IncLight emitting diode module
US3890170 *Nov 2, 1973Jun 17, 1975Motorola IncMethod of making a multicolor light display by graded mesaing
US3918053 *Aug 6, 1973Nov 4, 1975Dialight CorpDigital display
US3924227 *Nov 7, 1973Dec 2, 1975Michael StolovDigital display device
US3942065 *Nov 11, 1974Mar 2, 1976Motorola, Inc.Monolithic, milticolor, light emitting diode display device
US3950844 *Dec 19, 1974Apr 20, 1976The Marconi Company LimitedMethod of making L.E.D. arrays
US4019196 *Oct 24, 1975Apr 19, 1977Stanley Electric Co., Ltd.Indicating element and method of manufacturing same
US4303915 *Jul 11, 1979Dec 1, 1981Angelo George DSilent communicator
US5432015 *Apr 30, 1993Jul 11, 1995Westaim Technologies, Inc.Electroluminescent laminate with thick film dielectric
US5634835 *May 23, 1995Jun 3, 1997Westaim Technologies Inc.Electroluminescent display panel
US5679472 *May 23, 1995Oct 21, 1997Westaim Technologies, Inc.Electroluminescent laminate and a process for forming address lines therein
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US5756147 *Apr 28, 1995May 26, 1998Westaim Technologies, Inc.Method of forming a dielectric layer in an electroluminescent laminate
US6160528 *Dec 3, 1996Dec 12, 2000Schneider AutomationDisplay apparatus for programmable logic controllers
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DE2534608A1 *Aug 2, 1975Apr 1, 1976Litton Industries IncSichtanzeigeeinrichtung
U.S. Classification345/82, 257/92, 257/99, 313/500, 257/100, 257/93
International ClassificationG09F9/33, G09G3/14, G09G3/04
Cooperative ClassificationG09F9/33, G09G3/14
European ClassificationG09G3/14, G09F9/33