United States Patent fI9J
`Teshima et al.
`
`[54] COLORED-LIGHT EMITTING DISPLAY
`[75]
`Inventors: Toru Teshima, Yokohama; Jun-ichi
`Nishizawa, Sendai; Yasunori Kishi,
`Tokyo, all of Japan
`
`[73] Assignee: Stanley Electric Co., Ltd., Tokyo,
`Japan
`[21] Appl. No.: 84,384
`[22] Filed:
`Oct. 12, 1979
`[30]
`Foreign Application Priority Data
`Oct. 17, 1978 [JP]
`Japan ................................ 53-127726
`Oct. I 7, 1978 [JP]
`Japan ................................ 53-127727
`Oct. 17, 1978 [JP]
`Japan ................................ 53-127728
`Oct. 17, 1978 [JP]
`Japan ................................ 53-127729
`Int. Cl,3 ................................................ G08B 5/36
`[51]
`[52] U.S. CI ....................................... 340/702; 40/564;
`40/581; 340/366B; 340/782
`[58] Field of Search ............... 340/366 R, 366 B, 702,
`340/780, 782; 40/564, 58I, 582, 583
`References Cited
`U.S. PATENT DOCUMENTS
`Keenan .................................. 40/564
`4/1927
`Bone ........ ............ .................. 40/564
`4/1936
`Hart ................. ................ 340/366 R
`12/1964
`Gley ................................. 340/780 X
`1/1965
`10/1974
`Smith ............................... 340/366 B
`
`1,626,286
`2,038,409
`3,161,853
`3,163,949
`3,845,468
`
`[56]
`
`[I I]
`
`[45]
`
`4,271,408
`Jun. 2, 1981
`
`4,056,733 11/1977
`Prestridge ........................ 340/782 X
`Primary Examiner-David L. Trafton
`Attorney, Agent, or Firm-Cushman, Darby & Cushman
`
`ABSTRACT
`[57]
`A plurality of cellular concave mirror surfaces are
`formed on a plate-like reflector unit, and a plurality of
`light-emitting diodes are disposed on these cellular con(cid:173)
`cave mirror surfaces to jointly form a colored light
`source. Connection wirings to be connected with a
`power supply source are provided on a substrate lami(cid:173)
`nated with the reflector unit. A lamp base of a conven(cid:173)
`tional type may be coupled to the substrate for being
`electrically connected to the; wirings. This colored light
`source can provide a single or multiple color displays.
`Improved shadow pattern display can be provided by
`forming a complementary color pattern on a front
`cover lens. Letter, symbol or pattern display can be
`provided by selectively arrangiillg light-emitting diodes
`on the reflector unit. In case the above-mentioned light
`source is used as a traffic signal device, power dissipa(cid:173)
`tion and maintenance care are reduced by the light(cid:173)
`emitting diodes having low power consumption and
`long service life, and high security of the traffic is as(cid:173)
`sured by the elimination of false indications caused by
`external lights.
`
`20 Claims, 23 Drawing Figures
`
`3~
`3a.)u!f
`
`3
`
`3
`
`2a
`2a" 2b
`2b''
`
`IPR PAGE 1
`
`Acuity v. Lynk
`Acuity Ex.
`
`1012
`
`

`
`U.S. Patent
`
`Jun. 2, 1981
`
`Sheet 1 of 5
`
`4,271,408
`
`FIG. 1
`
`FIG. 2
`3~
`3a»
`
`3
`
`5
`
`3
`
`2a
`
`2a"
`
`2b
`2b"
`
`FIG. 3
`
`1b
`
`1a
`
`FIG. 4
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`3
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`5a
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`5b
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`FIG. 6
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`FIG. 7
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`FIG. B:
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`
`IPR PAGE 2
`
`

`
`U.S. Patent
`
`Jun. 2, 1981
`
`Sheet 2 of 5
`
`4,271,408
`
`FIG. 9
`
`1a
`
`FIG. 10
`
`FIG. 11
`15
`
`FIG. 12
`
`IPR PAGE 3
`
`

`
`U.S. Patent
`
`Jun. 2, 1981
`
`Sheet 3 of 5
`
`4,271,408
`
`FIG. 13
`
`FIG. 14
`
`IPR PAGE 4
`
`

`
`U.S. Patent
`
`Jun. 2, 1981
`
`Sheet 4 of 5
`
`4,271,408
`
`FIG. 75A
`
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`0
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`FIG. 758
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`23
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`RL
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`FIG. 76
`
`23a
`
`23
`
`24
`
`28
`
`25
`
`IPR PAGE 5
`
`

`
`U.S. Patent
`
`Jun. 2, 1981
`
`Sheet 5 of 5
`
`4,271,408
`
`FIG. 17
`[/;10
`RLl i GLl
`
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`I
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`FIG. 18
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`
`FIG. 19
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`
`FIG. 21
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`38
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`37
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`39
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`FIG. 20
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`
`IPR PAGE 6
`
`

`
`1
`
`COLORED-LIGHT EMITTING DISPLAY
`
`4,271,408
`
`BACKGROUND OF THE INVENTION
`(a) Field of the Invention
`The present invention relates to a display device, and
`more particularly it pertains to a colored-light display
`device utilizing light-emitting diodes serving as light
`source constituting elements.
`(b) Description of the Prior Art
`Most of the colored-light emitting display devices,
`such as traffic signal devices and railroad signal devices,
`employ incandescent lamps serving as light sources, and
`also color filter means for coloring the display lights.
`For example, a city road traffic signal device comprises 15
`a plurality of lamp units, each comprising a reflecting
`mirror, an incandescent lamp disposed on the reflecting
`mirror to serve as the light source, and a colored.front
`cover lens arranged in the foreground of the reflecting
`mirror. The reflecting mirror, the light source and the 20
`cover lens are arranged at predetermined positions
`within a housing. City traffic continues day and night
`throughout the year, and hence the city traffic signal
`devices mostly are required to be operated day and
`night for the control and security of the traffic. This 25
`means that the incandescent lamps serving as the light
`sources of such traffic signal devices should be turned
`on and off frequently day and night. Furthermore, traf-
`fic signal devices which are installed outdoors are sub(cid:173)
`jected directly to varying severe environmental condi- 30
`tions such as temperature and weather. Therefore, there
`are many factors that can cause malfunctions of the
`signal device, including disconnection of lamps. Thus,
`sufficient care, and hence considerable cost, need to be
`paid for the maintenance of the system. Furthermore,
`since the incandescent lamp supplies only white color
`lights, a coloring filter such as a colored cover lens is
`required for coloring the display lights. Filtering away
`of those unnecessary lights other than the light of a
`desired color such as green, yellow or red results in a 40
`reduction in the intensity of illumination or brightness
`and also in a low efficiency of conversion of electric
`power to a usable light energy. To compensate for such
`low efficiency, it is inevitable to use a light source of
`high wattage for obtaining sufficient brightness of dis- 45
`play. A large power consumption, however, contrib(cid:173)
`utes to a large heat generation, and leads to a remark(cid:173)
`able rise of the temperature within the lamp housing.
`Therefore, consideration should be paid not only to
`finding means to cope with the variations in the envi- 50
`ronmental conditions, but also to find means to cope
`with the variations of the temperature within the lamp
`housing. Such being the actual circumstances, the over-
`all structure of signal devices for controlling the city
`traffic has tended to be large in size and complicated in 55
`mechanism. Signal devices for controlling the railway
`traffic have similar problems also.
`Furthermore, another problem comes to the fore in
`case a signal lamp device which is provided with a
`coloring filter at the front cover or foreground surface 60
`of the device is installed at such location where the
`coloring filter is subjected to direct irradiation of inten(cid:173)
`sive lights such as the sunlight. Such sunlight which is
`transmitted to the device through the coloring filter is
`subjected to being colored through the filtering func- 65
`tion thereof, and is reflected by the reflector member or
`like member, and is caused thereby to emit outwardly of
`the device through this filter. Such reflected colored
`
`2
`light from the signal lamp device could tend to give
`false indication to the viewer as if the signal which, in
`reality, is turned off looks like working. This kind of
`false indication cannot be prevented in those conven-
`5 tional signal devices having such structure as stated
`above. Such false indications could lead to traffic acci(cid:173)
`dents. Among the conventional traffic signals, shadow
`signal lamp devices intended for pedestrians such as a
`device which displays a shadow figure of a moving
`ID person against a blue-color background or a shadow
`figure of a waiting or standing-still posture on a red(cid:173)
`color background tend to have the above-said problems
`especially, because of the relatively low degree of
`brightness of the colored display surface and/or be(cid:173)
`cause of the white or semi-transparent shadow figures
`provided on the surface of the device. Similar signal
`lamp devices include a colored "GO" and "STOP"
`sings.
`As will be understood from tlh.e foregoing statement,
`most of the inconveniences and drawbacks of those
`conventional colored-light emitting display devices
`may be attributed to the use of a combination of an
`incandescent lamp and a coloring filter.
`For the purpose of colored-light display, the employ-
`ment of light-emitting diodes is advantageous as com(cid:173)
`pared with the incandescent lamps, with respect to such
`aspects as low power operation, negligible heat genera(cid:173)
`tion, long service life and high luminous effciency. Fur-
`ther development of colored-light display devices using
`light-emitting diodes have been demanded.
`
`SUMMARY OF THE INVENTION
`It is, therefore, an object of tlh.e present invention to
`35 provide a colored-light emitting display device which is
`simple in structure and has an improved luminous effi-
`ciency.
`Another object of the present invention is to provide
`a colored-light emitting display device as described
`above, which is practically free of disconnections from
`the light source and needs little care for its maintenance.
`Still another object of the present invention is to
`provide a colored-light emitting display device of the
`type as described above, which is practically free of
`making false indication regardless of ambient conditions
`of light.
`A further object of the present invention is to provide
`a colored-light emitting display device of the type de(cid:173)
`scribed above, which is capable of selectively display(cid:173)
`ing a plurality of colored signals on a same front display
`surface.
`According to an embodiment of the present inven(cid:173)
`tion, there is· provided a signal device comprising a
`housing carrying therein a transparent or semitranspar(cid:173)
`ent colorless front cover lens, a substrate carrying
`thereon electric connection wiring led to a power sup(cid:173)
`ply source, a plate-like reflector unit laminated on said
`substrate and having thereon a plurality of individual
`cellular concave mirror surfaces, and a plurality of
`light-emitting diodes disposed on the cellular concave
`mirror surfaces and connected to the wirings arranged
`on the substrate for being energized to emit colored
`lights. Each of said cellular concave mirror surfaces of
`the reflector unit is provided witlh. a light-emitting diode
`so that the distribution of light emitted therefrom can be
`controlled very effectively by the concave mirror sur(cid:173)
`face. The employment of light-emitting diodes elimi(cid:173)
`nates the use of a color filter, and enables the device to
`
`IPR PAGE 7
`
`

`
`3
`carry out a lowpower and high brightness operation,
`and provides a semi-permanent service life.
`A lamp base of a conventional type may be connected
`to the wirings-carrying substrate to afford compatibility
`with and convenience for the conventional light-signal
`systems.
`According to another aspect of the present invention,
`there is provided a light-emitting signal device which
`enables a complementary color pattern to be provided
`on preferably the inner surface of the front cover lens to 10
`provide a black shadow display on a colored back(cid:173)
`ground. Selective superposed shadow displays can be
`provided also by the employment of lights of different
`colors. Recognition of the displayed signal can be
`highly enhanced through the non-false display arrange- 15
`ment including the transparent front cover lens.
`According to still another aspect of the present inven(cid:173)
`tion, there is provided a light-emitting signal device
`which enables selective displays of different colors on a
`same display surface to be achieved easily by the em- 20
`ployment of a selection switch and a plurality of groups
`of light-emitting diodes which are operatively con(cid:173)
`nected to this switch, each group including series-con(cid:173)
`nected light-emitting diodes and emitting a particular
`color of their own.
`According to a further embodiment of the present
`invention, each light-emitting diode is surrounded by
`frame walls having open opposite ends. This arrange(cid:173)
`ment enhances the clarity of a pattern display because 30
`the effect of the ambient lights is reduced by this frame
`wall and because the emitting light of the diode is pre(cid:173)
`vented from diffusing divergently.
`According to a still further embodiment of the pres(cid:173)
`ent invention, plural series connections oflight-emitting 35
`diodes are connected in parallel, and this arrangement
`allows one to make free selection of the driving voltage
`to vary the intensity of the output light.
`Furthermore, by driving light-emitting diodes with
`an ac power, the power source can be simplified, and 40
`brings forth compatibility with the conventional sys(cid:173)
`tem.
`These as well as other objects, the features and the
`advantages of the present invention will become appar(cid:173)
`ent by reading the following detailed description of the 45
`preferred embodiments when taken in conjunction with
`the accompanying drawings.
`
`25
`
`FIG. 9 is a diagrammatic perspective exploded ex(cid:173)
`planatory illustration of a part of an assembly of a sub(cid:173)
`strate and a reflector unit carrying light-emitting diodes
`for use, generally, in various embodiments of the pres-
`5 ent invention;
`FIG. 10 is a circuit diagram of a selective colored
`light display lamp device;
`FIG. 11 is a diagrammatic cross-sectional view of a
`lamp unit; and
`FIG. 12 is a diagrammatic plan view of a part of a
`reflector unit showing the arrangement of light-emit(cid:173)
`ting diodes of three different colors.
`FIGS. 13 through 17 represent another embodiment
`of the present invention, in which:
`FIG. 13 is a diagrammatic representation of a general
`perspective view of the device;
`FIG. 14 is a diagrammatic perspective view of a part
`of an assembly of a reflector unit carrying light-emitting
`diodes, frame walls assigned for separating the respec(cid:173)
`tive cells of the light-emitting diodes, and a front cover
`panel or lens;
`FIGS. 15A and lSB are a diagrammatic front view
`showing the arrangement of light-emitting diodes for
`providing letter signals;
`FIG. 16 is a diagrammatic cross-sectional view of a
`part of a lamp device of FIG. 14; and
`FIG. 17 is a circuit connection diagram for use in the
`device of FIG. 14.
`FIG. 18 is a diagrammatic representation of a front
`view of a display device intended for selective display
`of different signals on a same display surface.
`FIG. 19 is a diagrammatic illustration of a unit display
`area of the device containing two light-emitting diodes
`of different colors for two different color displays.
`FIG. 20 is a diagrammatic illustration of a shadow
`display signal device according to another embodiment
`of the present invention, for displaying two different
`shadows, one at a time, on two display devices.
`FIGS. 21 and 22 are another embodiment of the pres(cid:173)
`ent invention intended for selective shadow display, in
`which:
`FIG. 21 is a diagrammatic front view of a part of the
`display device; and
`FIG. 22 is a diagrammatic representation of arrange(cid:173)
`ment of light-emitting diodes of two different colors.
`
`4,271,408
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a diagrammatic explanatory perspective 50
`view, taken at the back, of a light-emitting diode lamp
`device according to an embodiment of the present in(cid:173)
`vention.
`FIG. 2 is a diagrammatic perspective exploded ex(cid:173)
`planatory illustration of a part of an assembly of a sub- 55
`strate and a reflector unit carrying light-emitting diodes
`for use, generally, in various embodiments of the pres(cid:173)
`ent invention.
`FIG. 3 is a diagrammatic perspective illustration of
`an alternative structure of individual concave surfaces 60
`of the reflector unit for substituting the reflector unit
`shown in FIG. 2.
`FIG. 4 is a circuit connection diagram to be em(cid:173)
`ployed in the embodiments of the present invention.
`FIGS. 5 through 8 are partial circuit diagrams for 65
`substituting part of the circuit of FIG. 4.
`FIGS. 9, 10, 11and12 are another embodiment of the
`present invention, in which:
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`In accordance with the present invention, there are
`materialized various types of colored-light emitting
`signal lamp devices as a substitution of the conventional
`combination of an incandescent lamp and a coloring
`filter, by the employment of light-emitting diodes.
`Description will hereunder be made of some pre(cid:173)
`ferred embodiments of the present invention.
`FIG. 1 shows a diagrammatic perspective view of a
`lamp body as viewed from its rear side, according to an
`embodiment of the present invention. This lamp body
`includes a plate-like reflecting mirror unit 1, a substrate
`2 underlying this mirror unit 1 and carrying thereon
`electric connections, and a lamp base 5 illustrated in the
`form of Edison base. The reflecting mirror unit 1 and
`the substrate 2 may be integrally formed into a single
`unit, or they may be formed separately and then the two
`may be assembled together to provide an integral body.
`The lamp base may be of any other type than the Edison
`base. For the purpose of providing a sufficient amount
`
`IPR PAGE 8
`
`

`
`4,271,408
`
`5
`(flux) of light, a multiplicity of light-emitting diodes are
`mounted on the reflecting mirror unit l.
`FIG. 2 shows an example of the manner of arranging
`said multiplicity of light-emitting diodes on the reflect(cid:173)
`ing mirror unit 1 as well as the manner of connecting 5
`these light-emitting diodes to printed wirings carried on
`the substrate 2. These plural light-emitting diodes 3 emit
`lights of a certain color such as red, yellow or green.
`For enriching the hue of the emitting lights, there may
`be employed a combination of a plural kinds of light- 10
`emitting diodes. The reflecting mirror unit 1 is formed
`as an integrally molded plastic (synthetic resin) plate
`having a multiplicity of mirror cells la which are
`formed with spherical or parabolic cellular concave
`individual surfaces arranged on one surface of the plate. I 5
`These mirror surfaces may be formed with a metal such
`as aluminum deposition. For example, aluminum is
`vacuum-deposited on a mirror plate and a transparent
`thin protective resion or dielectric film may be coated
`thereon. At the central portion of each reflecting mirror 20
`cell la, there is provided a socket 4 for loading a light(cid:173)
`emitting diode 3. The mirror surface which forms one
`cell la is designed so as to be able to effectively lead the
`light emitting from the mating light-emitting diode 3 in
`a predetermined direction. The multiplicity of light- 25
`emitting diodes 3 combined with the corresponding
`multiplicity of mirrors cells la jointly form an overall
`light source for irradiating lights of a desired color in
`the desired directions. The solid angle of the emitting
`lights can be adjusted easily and in a wide range by 30
`designing the shape of the respective cellular mirror
`surfaces la in a desired manner and by selecting the
`positions of the light-emitting diodes 3 which are ar(cid:173)
`ranged on these mirror surfaces. It should be noted that
`a parabolic mirror cell has an ability of directing light 35
`rays much superior to that of a spherical mirror cell.
`Selection of the mirror shape may be done in accor(cid:173)
`dance with the specific purpose. If desired, a combina(cid:173)
`tion of various different shapes of mirror cells may be
`adopted.
`The substrate 2 is made with a board of an insulating
`material carrying a metal layer printed thereon for elec(cid:173)
`trically connecting the multiplicity of light-emitting
`diodes. This substrate 2 is adapted to be brought into a
`close or tight contact with the bottom surface of the 45
`reflector mirror unit 1. In the example shown in FIG. l,
`there are formed a plurality of printed wirings 2a, 2b, 2c,
`... on that surface of the insulator board 2 on which the
`mirror member 1 is brought into contact. The adja(cid:173)
`cently located end portions 2a" and 2b' of the adja- 50
`cently located wirings 2a and 2b jointly constitute a pair
`of receptors for a pair of terminals 3a of a single light(cid:173)
`emitting diode 3 for the electric connection of this di(cid:173)
`ode. Likewise, the two end portions 2b" and 2c' of the
`two wirings 2b and 2c jointly form a pair of receptors 55
`for the connection of another light-emitting diode 3. In
`this way, a plurality of light-emitting diodes 3 may be
`electrically connected in series through these wirings
`2a, 2b, 2c, .... Since a single light-emitting diode has a
`low driving voltage such as about 1.6 to 1.8 volts in case 60
`of a red-light emitting gallium-aluminum arsenide (Gax(cid:173)
`Al1-xAs, wherein O<x< I) diode, multiplication of
`such unit driving voltage is advantageous for the driv(cid:173)
`ing of the light-emitting diode circuit by a commercial
`power supply or like power source. For example, a 65
`series connection of 62 light-emitting diodes each hav(cid:173)
`ing a driving voltage of 1.6 volts will make the total
`driving voltage of about de 100 volts.
`
`6
`In case a single series connection of light-emitting
`diodes is unable to provide a sufficient intensity of light
`(illumination), there may be formed a parallel connec(cid:173)
`tion of such series connection, as. will be described later.
`The rear surface of the substrate 2 mentioned above is
`coupled to, for example, a lamp base 5 (see FIG. ll). In
`FIG. 1, the substrate 2 has, on its back side, a guide
`projection 2d, and the lamp base 5 is coupled tightly
`thereto by, for example, an adhesive agent or like
`means. The printed wirings 2a, 2b, 2c, ... and the termi(cid:173)
`nals of the lamp base 5 are electrically connected to-
`gether by means of the socket. Alternatively, it will be
`apparent that soldering, compressed bonding and like
`means may be employed. It will be noted also that each
`of the light-emitting diodes may be replaced by a fresh
`one by merely removing it out of its mating socket 4 and
`inserting a new one into this socket.
`An alternative structure of the reflecting mirror unit
`1 is shown in FIG. 3. In this example, each mirror cell
`la of the mirror unit 1 is provided with no socket 4 for
`a light-emitting diode 3, but instead .the mirror cell lla is
`provided with a through-aperture lb. Each of the light(cid:173)
`emitting diodes 3 is mounted directly on the substrate 2
`by inserting, via this through-aperture lb, the terminals
`3a of a light-emitting diode 3 into the receptors 2a" and
`2b', for example, of the wiring formed through the sub(cid:173)
`strate 2, after passing through the mirror unit 1.
`FIG. 4 shows an example of the circuit diagram for
`electrically connecting a pluralitty of light-emitting di(cid:173)
`odes. Input terminals Sa and Sb represent the contact
`points of the lamp base S and they are connected to an
`ac power supply not shown. A full-wave rectifying
`circuit 6 is connected between the input terminals Sa
`and Sb for supplying a pulsating de power to the device.
`A capacitor C forms a smoothing circuit for absorbing
`ripple components of the power supply and for supply(cid:173)
`ing a smoothed de power to the light-emitting diodes. A
`protective resistor R is connected in series with a diode
`40 circuit 13. It should be understood that the rectifying
`circuit, the smoothing circuit and the protective resistor
`may be mounted inside the lamp base and/or on the
`substrate 2. As noted in FIG. 4, tlhe light-emitting diode
`circuit 13 includes a parallel connection of two series
`connections of light-emitting diodes 3. The number of
`light-emitting diodes 3 in each series connection may be
`determined by giving consideration to the input volt(cid:173)
`age. Each series connection of light-emitting diodes
`may be considered as a component unit light source.
`Then, two such light source units are connected in
`parallel to raise the output light intensity in FIG. 4. It
`will be apparent that the number of such unit light
`sources may be selected arbitrarily to meet the desired
`light output. Various alterations and modifications of
`the diode circuit 13 is possible.
`.
`FIG. S is a modification of a diode circuit arrange(cid:173)
`ment shown in FIG. 4, and a protecting resistor R1 and
`another protecting resistor R2 are connected in series
`respectively to the respective series connections of the
`light-emitting diodes 3. These protecting resistors R1
`and R2 may preferably be adjustable resistors which can
`balance the current dividing ratio and can compensate
`for the excess voltage which might be applied to the
`light-emitting diodes during, for example, the step of
`adjustment of the luminous intensity of the lamp device.
`In case two series connections olf light-emitting diodes
`are employed as shown in FIG. 5, one of these two
`resistors R1 and R1 may be dispensed with.
`
`IPR PAGE 9
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`4,271,408
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`7
`FIG. 6 is a modification of the diode circuit arrange(cid:173)
`ments shown in FIG. 4 and 5. In this example, an addi(cid:173)
`tional series connection of light-emitting diodes 3 is
`connected in parallel, through a switching means 7, to
`the series connection of diodes 3 for varying the inten- 5
`sity of the output lights. This switch 7 may be closed
`during the daytime to give out a higher luminous flux,
`while it may be opened during the night time to reduce
`the luminous flux. Thus, a clear display can be achieved
`even in the circumstance wherein the intensity of the 10
`ambient light is great. Along therewith, this arrange(cid:173)
`ment serves to minimize wasteful power dissipation
`during the night time.
`FIG. 7 shows a further modification of the light-emit(cid:173)
`ting diode circuit arrangement, in which a capacitor 8 is 15
`connected to one or more of the series connections of
`light-emitting diodes 3. As will be understood by those
`skilled in the art, a phase shift is generated in the current
`which flows through the light-emitting diodes con(cid:173)
`nected in series to this capacitor 8, and thus this ar- 20
`rangement serves to prevent the occurrence of flickers.
`A light-emitting diode is capable of enduring a re(cid:173)
`verse voltage below the reverse breakdown voltage.
`Thus, a light-emitting diode circuit may be actuated by
`an ac power as well as by a de power. FIG. 8 shows an 25
`example of a light-emitting diode circuit arrangement
`for ac drive. A pair of light-emitting diodes of opposite
`polarities relative to each other are connected in paral(cid:173)
`lel, and a plurality of such pair connections are con(cid:173)
`nected in series. The series connection is directly con- 30
`nected to an ac power surce through a protective resis(cid:173)
`tor R, without the intervention of a rectifier circuit nor
`a smoothing circuit which is the case in FIG. 4. One of
`a pair of light-emitting diodes 3 emits light for every
`one half cycle and the other of the pair of the light-emit- 35
`ting diodes emits light for every other half cycle. Thus,
`the provision of a full-wave rectifier circuit is not
`needed.
`According to those embodiments mentioned above,
`traffic signal lamp devices are formed by utilizing light- 40
`emitting diodes to serve as the light source, and hence
`the device has a semi-permanent service life, and mark(cid:173)
`edly reduces cares required for the maintenance as com(cid:173)
`pared with those signal devices using conventional in(cid:173)
`candescent signal lamps, and thus can simplify the struc- 45
`ture because the provision of a coloring filter is not
`required, nor the provision of a heat radiating means. A
`desired amount of colored light can be emitted from the
`device by appropriately selecting the number of light(cid:173)
`emitting diodes in a series connection of the arrange- 50
`ment as well as the number of the series circuits con(cid:173)
`nected in parallel. Also, a convenient driving voltage
`can be selected by the adjustment of the number of the
`light-emitting diodes in each series circuit.
`The emitting light rays can be effectively directed to 55
`desired directions by the use of parabolic and/or spheri(cid:173)
`cal reflecting mirror cells which accommodate light(cid:173)
`emitting diodes, respectively. Particularly well oriented
`light rays can be obtained easily for road traffic signals
`and also for railroad traffic signals. Yet further, by as- 60
`sembling a lamp body as an integrated structure having
`a conventional lamp base, with the exception of the
`example of FIG. 6, the light-emitting diode lamp device
`can be made compatible with conventional signal lamp
`systems. A plurality of circuits as shown in FIG. 4 may 65
`be connected through a selection switch. Thus, the
`conventional signal systems utilizing incandescent light
`source can be reformed into those of light-emitting
`
`diodes step by step at each breakage of such incandes(cid:173)
`cent lamp. In emergency, the light-emitting diode lamp
`device can be replaced by an incandescent lamp. It
`should be noted that such arrangement as that shown in
`FIG. 6 saves the wasteful electric power in dark condi(cid:173)
`tion merely by the addition of a simple arrangement.
`The description made hereinabove has been directed
`mainly to those light-emitting diode lamp devices
`which emit light of a single color. The constituent light(cid:173)
`emitting diodes each has a very small dimension, and
`thus there can be arranged a plurality of or a number of
`light-emitting diodes on a single plane in various desired
`ways. Rows of either red, yellow or green light emitting
`diodes can be assembled in a single lamp body without
`any difficulty.
`FIGS. 9, 10 and 11 show an example of composite
`light-emitting diode lamp device which is capable of
`selectively emitting light of either red, yellow or green
`in color. In FIG. 9, a reflector unit 1 is formed with an
`integral mold of a synthetic resin and carries on one
`surface thereof a plurality of concave cellular reflecting
`mirror surfaces la each having a similar shape. A socket
`4 is provided in each of the reflecting mirror surfaces la
`at the central portion thereof for receiving the base
`portion of a light-emitting diode 3. A substrate 12
`carries on its surface a plurality of paired printed wir(cid:173)
`ings 12a, 12b, ... for supplying electric power to the
`light-emitting diodes. Each of the paired printed wir(cid:173)
`ings 12a, 12b, ... has a connection hole 12a', 12b', ...
`into which the base terminals not shown of the socket 4
`are to be inserted to provide electric connection. Since
`red, yellow and green light emitting diodes are arranged
`on a single entire lamp surface of the device, and each of
`the respective color diode groups is arranged neatly
`without being mingled among these different color light
`emitting diodes for avoiding confusion, the printed
`wiring arrangement in this example is little complicated
`as compared with the arrangement shown in FIG. 1.
`FIG. 10 shows a circuit diagram for actuating three
`groups of different color light emitting diodes. The
`full-wave rectifying circuit 6 and the smoothing capaci(cid:173)
`tor Care similar to those in FIG. 4. A selection switch
`means 10 is provided and is adapted to select the con(cid:173)
`nection of one of the three groups of the three different
`color light emitting diodes 3R, 3Y and 3G which, in
`turn, are provided at the ends of the rows thereof with
`their own protecting resistors R11, R12 and R13, respec(cid:173)
`tively. The respective groups 3R, 3Y and 3G are com(cid:173)
`prised of series connections of red, yellow and green
`light emitting diodes, respectively, and will emit red,
`yellow or green light by the selection of said switch
`connections. Although each group of color light emit(cid:173)
`ting diodes is shown to include only one series connec(cid:173)
`tion, there may be connected a plurality of series con(cid:173)
`nections in parallel relationship in each group in a man(cid:173)
`ner as shown in FIG. 4. The group 3R of red light
`emitting diodes is