United States Patent [191
`Waltz et al.
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`US005450301A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,450,301
`Sep. 12, 1995
`
`[54] LARGE SCALE DISPLAY USING LEDS
`[75]
`Inventors: Thomas M. Waltz, Newtown; Alfred
`Dagenais, Norwalk, both of Conn.
`[73] Assignee: Trans-Lux Corporation, Norwalk,
`Conn.
`[21] Appl. No.: 131,895
`[22] Filed:
`Oct. 5, 1993
`[51]
`Int. Cl.6 .............................................. G09F 13/00
`[52] U.S. CI •.................................... 362/231; 362/800;
`362/812; 40/544; 40/581; 340/815.45;
`340/815.65; 345/83
`[58] Field of Search ....................... 362/231, 800, 812;
`40/544, 581; 340/815.45, 815.65; 345/82, 83
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,887,074 12/1989 Simonet al .................... 340/815.45
`
`5,036,248 7/1991 McEwan et al .................... 362/800
`5,184,114 2/1993 Brown ................................... 345/83
`5,268,828 12/1993 Miura .................................. 362/812
`
`FOREIGN PATENT DOCUMENTS
`8604439 7/1986 WIPO ................................... 345/83
`
`Primary Examiner-Ira S. Lazarus
`Assistant Examiner-Sara Sachie Raab
`Attorney, Agent, or Firm-Kane, Dalsimer, Sullivan,
`Kurucz, Levy, Eisele & Richard
`
`[57]
`ABSTRACf
`A large scale display is made of several panels, each
`holding several display elements defined by LEOs.
`Preferably, each panel is arranged so that it can directly
`replace, both mechanically and electrically, a panel
`having incandescent bulbs as display elements.
`
`2 Claims, 3 Drawing Sheets
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`U.S. Pat. No. 7,038,399
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`1
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`5,450,301
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`LARGE SCALE DISPLAY USING LEDS
`
`BACKGROUND OF THE INVENTION
`
`2
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring now to the drawings, and more particu-
`5 lady to FIG. 1, a display 10 constructed in accordance
`with this invention consists of several panels 12. Each
`1. Field of Invention
`This invention pertains to large scale displays used,
`panel12 consists of a plurality of display elements 14. In
`FIGS. 1 and 3, the panel 12 has eight display elements
`for example, for traffic signs, and more particularly to
`14. A triac power controller 16 is provided to activate
`large scale displays which have elements selectively
`turned on and off to generate alphanumeric characters 10 each display element 14. (In FIG. 1 only a single con-
`or graphic patterns.
`troller 16 is shown for the sake of clarity, however it
`2. Description of the Prior Art
`should be understood that each display element 14 is
`Large scale displays are used for various purposes at
`coupled to an identical power controller as described
`sports stadiums, on the highways, and so on to display
`below). Controller 16 receives power for the respective
`selected messages. Presently, there are two types of 15 display element 14 from an AC line 18. The AC output
`of the power controller is rectified by a full wave recti-
`displays which are prevalent. One is an electromechani-
`cal type formed of a plurality of windows arranged in
`fier bridge 20. The bridge 20 generates a corresponding
`DC voltage on its output terminals 22 and 24 which
`grids and small two-colored panels arranged behind the
`feed to the display 14 through a series resistor 26.
`windows which can be moved to render each window
`either color or the other (i.e. black or amber). A disad- 20 Additionally, a resistor 28 is coupled in parallel to the
`output of the triac power controller to draw a small
`vantage of this type of display is that since it is mechani-
`holding current for the triac power controller 16.
`cal, it requires frequent maintenance. Moreover, at
`night, external lights are required to illuminate the dis-
`As shown in more detail in FIG. 2, display 14 consists
`play. The second prevalent display type consists of a
`of a plurality of LED assemblies 30, each diode assem-
`plurality of incandescent bulbs arranged in preselected 25 bly 30 c_onsisting of t~o ~iodes 32, 34 connec~ed in
`parallel m the same drrect10n. In FIG. 2, the display
`arrays for example 8X5. Various alphanumeric charac-
`ters can be displayed in each array by selectively ener-
`element 14 consists of 57 diode assemblies 30. The LED
`gizing some of the bulbs. A problem with this type of
`assembl_i~s 30 are ~onnected in series _and are coupled to
`display is that the bulbs have a relatively short life and
`the p~Sitive t~rnrmal 22 through resisto~ 26 and to the
`hence must be changed frequently. Another problem is 30 n~gative te~nal24 as shown. I~ ol?erat10n, each of the
`d~odes of a display ~lements 14 IS sunultaneously ener-
`that when incandescent bulbs are used, power consump-
`tion is high and excess heat is generated.
`gu:ed through the tnac power controller 16. Controller
`16 can turn all of the diode assemblies 30 fully on, or
`they can be set to a partial brightness as required. The
`35 current from the controller flows through the rectifier
`20, terminal22, resistor 26, the diodes 32, 34 and back to
`terminal 24 and the common ground 46. The current
`through diodes 32, 34 is limited by resistor 26.
`Referring now to FIGS. 3 and 4, each panel 12 fur(cid:173)
`ther consists of a board 40 having two opposed faces 42,
`44. The LED assemblies are mounted on face 42 while
`the remaining electrical components (i.e. the resistors
`26, 28 and the rectifier bridge 20) can be mounted on
`face 44. Preferably, the LED assemblies 30 are closely
`packed and arranged in a substantially circular pattern
`to defme a respective display element 14. In FIG. 3, an
`array of 1 X 8 display elements 14 is shown. In this con(cid:173)
`figuration, panel12 can be made to the same dimensions
`and the same electrical requirements and connections as
`a standard panel having an array of 1 X 8 incandescent
`bulbs. Various regulatory authorities have prescribed
`that large scale display panels have certain formats. For
`example, the State of California has mandated that in(cid:173)
`candescent highway signs must be made of five replace(cid:173)
`able sections of eight incandescent bulbs each for a total
`for 40 display elements. This standard can be met by
`using five panels 12 ·such as illustrated in FIG. 3, each
`panel electrically and mechanically replacing a respec(cid:173)
`tive panel of incandescent bulbs.
`The LEDs 32, 34 come in various colors, however,
`green and red LEDs generate the most intensity. Some
`large scale displays are required to have characters of a
`certain color. If red or green display elements are re(cid:173)
`quired, then of course all the LEDs of a display element
`will have that color. However, in many instances, the
`display element must be amber, Such a display element
`may be generated by using both red and green assem(cid:173)
`blies closely packed together. It has been found that
`
`OBJECTIVES AND SUMMARY OF THE
`INVENTION
`In view of the above-mentioned disadvantages of the
`prior art, it is an objective of the present invention to
`provide a large scale display which makes use of semi(cid:173)
`conductor-based light elements which last much longer
`than incandescent bulbs.
`A further objective is to provide a display with light
`elements which are much more efficient than incandes(cid:173)
`cent bulbs and hence require much less power and gen-
`erate less heat.
`A further objective is to provide a semiconductor
`based display which is made up of modules that can
`readily replace incandescent bulb arrays.
`Other objectives and advantages of the invention
`shall become apparent from the following description. 50
`Briefly, a large scale display constructed in accordance
`with this invention consists of several boards, each
`board having an array of semiconductor light sources
`defming display elements. Advantageously, LEDs of
`various colors can be selected for each display element 55
`and arranged to generate a display element having a
`perceived color which is different from the colors of the
`LEDs.
`
`40
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`45
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`60
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`BRIEF DESCRIPTION OF THE FIGURES
`FIG. 1 shows a block diagram of a display con(cid:173)
`structed in accordance with this invention;
`FIG. 2 shows a schematic diagram of the LEDs for
`the display elements of FIG. 1;
`FIG. 3 shows a front view of a panel with several 65
`display elements; and
`FIG. 4 shows an enlarged partial cross-sectional view
`of the panel of FIG. 3.
`
`

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`5,450,301
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`3
`good results are obtained if the ratio of red to green
`assemblies is 1:2. Thus, an amber display element con(cid:173)
`sisting of 57 assemblies should include 19 red LED and
`38 green LED assemblies. As shown in FIG. 3, the
`assemblies 30 can be arranged so that except at the 5
`edges of the pattern (FIG. 3) every red assembly 30R is
`surrounded by six green assemblies 30G. In this manner,
`when the display 14 is on, a person looking at it from a
`distance will perceive it as an amber display element
`even though it is made of red and green LED assemblies 10
`30R, 30G wherein a red assembly 30D consists of two
`red LEDs and a green assembly 30G consists of two
`green LEDs.
`As previously mentioned, the panels 12 can be made
`to directly replace mechanically and electrically panels 15
`of incandescent bulbs. However, because panels 12
`have display elements made of LED assemblies, they
`are will last much longer before requiring maintenance
`since LEDs have much longer life than incandescent
`bulbs. In addition, the panels require less power and 20
`generate virtually no heat while generating substan(cid:173)
`tially the same amount of light as the incandescent
`bulbs.
`Obviously, numerous modifications may be made to
`this invention without departing from its scope as de- 25
`fmed in the appended claims.
`I claim:
`1. A large scale display comprising:
`a plurality of panels, each panel having a plurality of
`display elements, said panels being constructed and 30
`
`4
`arranged to form a rectangular array defined by
`said display elements;
`wherein each display element includes a plurality of
`LED diodes arranged in a preselected pattern on a
`respective panel;
`wherein at least one of said display elements includes
`a first set of diodes emitting red light and a second
`set of diodes emitting green light, said first and
`second sets of diodes cooperating to allow said
`display to be perceived as amber; and wherein at
`least one of said diodes emitting red light is sur(cid:173)
`rounded by and in contact with six diodes emitting
`green light.
`2. A replacement panel for incandescent bulb display
`panels, said replacement panel comprising;
`a board;
`a plurality of display elements mounted on said board,
`wherein each display element includes a plurality of
`LED diodes arranged in a preselected pattern on a
`respective panel;
`wherein at least one of said display elements includes
`a first set of diodes emitting red light and a second
`set of diodes emitting green light, said first and
`second sets of diodes cooperating to allow said
`display to be perceived as amber; and wherein at
`least one of said diodes emitting red light is sur(cid:173)
`rounded by and in contact with six diodes emitting
`green light.
`
`* * * * *
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