Color display system utilizing a matrix arrangement of triads

A color display system for use in stadiums, arenas or streets has a matrix of three-primary triads of light-emitting elements controlled by electric signals for displaying images, characters, and/or other patterns in colors. The color display system comprises display units arrayed in horizontal rows and vertical columns and each having simplified electric connector means for external electric connection and means for effectively cooling the light-emitting elements which are packed at high density. Each of the display units has two horizontal rows of light-emitting elements mounted on a front panel of a display unit body, a control circuit housed in the body, and electric connector means mounted on a rear panel of the body. The display units are located closely in each horizontal row and spaced at intervals in each vertical column. A ventilator is disposed behind the display units for cooling the light-emitting elements. Various support arrangements are provided for stably supporting the display units which may have an increased depth.

BACKGROUND OF THE INVENTION 
The present invention relates to a color display system to be installed in 
stadiums, arenas, or streets for displaying images, characters and/or 
other patterns in colors by controlling a matrix of triads of 
light-emitting elements capable of emitting three primary colors with 
electric signals. 
Known electric display systems installed in stadiums, arenas, streets or 
other public facilities and spaces comprise a matrix of incandescent lamps 
controlled by electric signals for displaying characters, images, and/or 
other patterns in monochromatic tones. As long as only characters are to 
be displayed, monochromatic display systems are usually satisfactory. 
However, monochromatic display systems have proven unattractive if images 
or graphic patterns are to be displayed thereon. To cope with this 
problem, there has been developed in the recent past a system composed of 
a matrix of three-primary triads of light-emitting elements for displaying 
colored images. Where only the colors of the light-emitting elements are 
to be displayed, the color display system is subjected to no technical 
difficulty since the density of light-emitting elements per unit area is 
not required to be increased. Where any images are to be displayed in 
natural colors by mixing the three primary colors, however, the 
light-emitting elements have to be packed at a much higher density, 
resulting in a variety of technical difficulties to be solved. More 
specifically, a color display system capable of displaying images and 
graphic patterns in various colors by mixing the three primary colors 
requires that about thirty to ninety thousand light-emitting elements be 
packed at an increased density such as at a pitch or inter-element 
interval of about 22 to 45 mm. Such a color display system is 
disadvantageous in that it is quite large in scale, is highly difficult to 
install, and a large amount of heat will be generated by the matrix of 
light-emitting elements. 
One electric color display system which has heretofore been developed 
comprises a number of bar-shaped parallel display units each composed of 
an array of light-emitting elements. Two adjacent display units serve as 
one set of triads of light-emitting elements of three primary colors. 
Therefore, two separate trains of electric signals have to be applied to 
the display units in each triad set, thus requiring a complex wiring 
arrangement. Since there are required at least as many lead wires as there 
are light-emitting elements, a large number of cables are necessary for 
connection of the light-emitting elements to a control circuit disposed 
behind the display units. It is a tedious and time-consuming task to lay 
and connect those cables. The cables need a large installation space 
behind the display units and result in a substantial increase in the cost. 
In addition, only a limited space is available for the installation of a 
ventilator for cooling the light-emitting elements. 
Another prior color display unit is in the form of a rectangular 
parallelopied supporting on its face a matrix of light-emitting elements. 
Such a display unit, particularly those light-emitting elements close to 
the center thereof, cannot sufficiently be cooled for heat dissipation by 
a ventilator positioned behind the display unit. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a color display system 
which will eliminate the foregoing conventional drawbacks. 
Another object of the present invention is to provide a color display 
system composed of a plurality of display units which are appropriately 
unitized for easy installation and wiring. 
Still another object of the present invention is to provide a color display 
system having simplified electric connector means for external connection. 
A still further object of the present invention is to provide a color 
display system having means for effectively cooling a multiplicity of 
light-emitting elements packed at a high density. 
To achieve the above objects, a color display system according to the 
present invention comprises a plurality of display units each composed of 
a body having a front panel supporting two rows of sockets thereon, two 
rows of light-emitting elements mounted respectively in the sockets and 
capable of emitting light of three primary colors, the light-emitting 
elements being grouped into a horizontal array of triads across the two 
rows of light-emitting elements, a control circuit unit accommodated in 
the body and including a printed-circuit board electrically connected to 
the sockets for controlling the light-emitting elements, and electric 
connector means electrically connected to the control circuit unit for 
external electric connection. The color display system also includes 
support means for supporting the display units as a matrix of horizontal 
rows and vertical columns, the display units being disposed closely in 
each of the horizontal rows and spaced in each of the vertical columns 
with passages defined between the display units in the vertical columns, 
and ventilator means disposed behind the display units for forcibly 
delivering air through the passages. 
With the above arrangement, each single display unit supports three-primary 
triads of light-emitting elements with signal lines connected thereto 
being disposed in the body without the need for many cables for external 
connection. The air delivered from the ventilator means is passed through 
the passages between the vertically spaced display units for cooling the 
sockets and the light-emitting elements. The bodies of the display units 
are shaped so that the adjacent display units in each horizontal row are 
disposed closely to each other, and the sockets are disposed on the front 
panel of the body so that the body has a height held to a minimum. The 
control circuit unit housed in the display unit body is arranged to 
simplify the electric connector means and deliver control signals from 
display unit to display unit in each horizontal row. Various support 
arrangements are provided for stably supporting the display units which 
may have an increased depth. 
The terms "front", "rear", "upper", and "lower" are employed with reference 
to the normal posture of use of the color display system throughout the 
specification and claims. 
The above and other objects, features and advantages of the present 
invention will become more apparent from the following description when 
taken in conjunction with the accompanying drawings in which a preferred 
embodiment of the present invention is shown by way of illustrative 
example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 through 7 illustrate a color display system according to a first 
embodiment of the present invention, the color display system being 
suitable for installation in an open stadium. The color display system 
comprises a plurality of display units 1. Each of the display units 1 is 
composed of a body 2 made of metal such as aluminum, as shown in FIG. 1. 
The body 2 comprises an upper chassis 3 and a lower chassis 4. The upper 
chassis 3 has a front panel 5, an upper panel 6, a pair of side panels 7, 
8, and a narrow lower panel 9 including an inner stepped portion. The 
front panel 5, the upper panel 6, and the lower panel 9 are integrally 
formed by extrusion molding, and the side panels 7, 8 are welded to the 
opposite side edges of the front panel 5, the upper panel 6, and the lower 
panel 9. The lower chassis 4 is composed of a lower panel 11 having a 
ridge 10 extending along a front edge thereof and projecting downwardly 
from a lower surface of the lower panel 11, a rear panel 13 having a ridge 
12 extending along an upper edge thereof and projecting forward from an 
inner surface of the rear panel 13, and a pair of side ridges 14, 15 
mounted on opposite ends of the inner surface of the rear panel 13. The 
lower and rear panels 11, 13 are integrally formed by extrusion molding, 
and the side ridges 14, 15 are welded to the rear panel 13. 
The front panel 5 of the upper chassis 3 has two rows of socket attachment 
holes 16. A plurality of sockets 17 are installed respectively in the 
socket attachment holes 16. Each of the sockets 17 has an outer casing 
molded of synthetic resin and includes a terminal support 18 projecting 
from an end thereof through a annular water-resistant packing 19 of rubber 
into each of the socket attachment holes 16. The socket 17 is secured to 
the front panel 5 by means of screws 21 disposed behind the front panel 5 
and threaded into a pair of attachment legs 20 projecting laterally from 
the end of the socket 17 in diametrically opposite relation. The 
attachment legs 20 are inclined with respect to the horizontal plane so 
that the attachment legs 20 of the adjacent sockets 17 will not interfere 
with each other and the sockets 17 can be packed at a higher density. 
Since the attachment legs 20 are also inclined with respect to the 
vertical plane, the height of the upper chassis 3 and hence the body 2 is 
held to a minimum for maintaining necessary ventilation spaces or air 
passages (described later on) between the display units 1. 
Each socket 17 includes a water-resistant packing 22 of rubber fitted over 
the peripheral edge around an open end. A light-emitting element 23 is 
inserted through the water-resistant packing 22 into the socket 17. The 
light-emitting element 23 comprises an incandescent lamp having a light 
reflecting film 24 of metal deposited on a rear circumferential surface 
thereof, and a colored light transmission film 25 painted on a front 
surface thereof. There are three types available of the light-emitting 
element 23; one capable of emitting red (R) light, one capable of emitting 
green (G) light, and one capable of emitting blue (B) light, the red, 
green, and blue being three additive primaries. The light-emitting 
elements 23 are mounted respectively in the sockets 17 and arranged in two 
rows on the front panel 5 of the body 2. Three adjacent light-emitting 
elements 23 which emit light in the three primaries are grouped as a 
triad, and a plurality of triads are horizontally arranged across the two 
rows of the light-emitting elements 23. The three-primary triads are 
shaped as either a regular triangle or an inverted regular triangle, as 
best shown in FIG. 2. The regular and inverted regular triangles of the 
triads are alternately positioned along the front panel 5. The opposite 
sides of the body 2 are inclined at an angle of 60 degrees to the 
horizontal plane so as to be in conformity with the outer sides of the 
opposite triads. 
As shown in FIG. 5, a control circuit unit 27 having a printed-circuit 
board 26 is accommodated in each body 2. Lead wires 28 are electrically 
connected between the control circuit unit 27 and terminals 29 of the 
sockets 17 for enabling the control circuit unit 27 to control the 
light-emitting elements 23 with electric signals delivered over the lead 
wires 28. The control circuit unit 27 will be described later in detail. 
The rear portion of the body 2, that is, the rear panel 13 of the lower 
chassis 4, supports thereon three electric connector means electrically 
connected to the control circuit unit 27 and to external terminals. The 
three electric connector means include, as shown in FIG. 4, a signal inlet 
composed of a cable 31 fixed by a bushing 30 to the rear panel 13 and an 
electric connector 32 attached to an outer end of the cable 31, a signal 
outlet composed of an electric connector 33 mounted on the rear panel 13, 
and a power supply inlet composed of a cable 35 fixed by a bushing 34 to 
the rear panel 13 and an electric connector 36 attached to an outer end of 
the cable 35. 
For assembling the body 2, the front edge of the lower panel 11 of the 
lower chassis 4 is placed on the upper surface of the lower panel 9 of the 
upper chassis 3 so that the ridge 10 is held against the rear edge of the 
lower panel 9, and then the lower panels 9, 11 are fastened together by 
screws 37 (FIG. 5). The ridge 12 of the rear panel 13 of the lower chassis 
4 is held against the lower surface of the rear edge of the upper panel 6 
of the upper chassis 3, and the ridge 12 and the upper panel 6 are 
fastened to each other by screws 38. The side ridges 14, 15 are located 
inwardly of the rear edges of the side panels 7, 8 and fastened thereto by 
screws (not shown). The joints between the upper and lower chassis 3, 4 
are coated with a caulking material for rendering the assembly resistant 
to the entry of water. The printed-circuit board 26 is supported on a 
support member 39 affixed by screws 40 to the lower panel 11 of the lower 
chassis 4. 
As shown in FIG. 3, a pair of upper and lower light shield partitions 41 of 
metal is interconnected by a connector plate 42 having rear bent lug 43 
which are secured by screws 44 (FIG. 2) to a front surface of an 
attachment leg 45. The attachment leg 45 has ends fixed by screws 46 47 
(FIGS. 4 and 5) to the upper and front panels 6, 5 of the body 2. The 
upper and lower light shield partitions 41 are disposed one on each side 
of each of alternate horizontal rows of the light-emitting elements 23, so 
that any displayed images or patterns can clearly be seen on the matrix of 
the light-emitting elements even under sunlight. Each of the light shield 
partitions 41 has a plurality of heat radiation holes 48 for upwardly 
dissipating heat radiated from the light-emitting elements 23. 
The display units 1 are supported by a support arrangement composed of a 
vertical post 49 in the form of an H-shaped steel bar and a support plate 
51 of metal fastened by bolts 50 to a front surface of the vertical post 
49. The vertical post 49 and the support plate 51 are positioned across a 
joint between the rear portions of the bodies 2, 2 of adjacent display 
units 1, 1. Connectors 53 are fastened by bolts 52 to the rear portions of 
the bodies 2, 2, respectively, and also fastened by bolts 54 to the 
support plate 51. Since each vertical post 49 is shared by two 
horizontally adjacent display units 1, 1, the number of the vertical posts 
49 used is held to a minimum. This arrangement is of advantage for 
effective ventilation as described later. Each connector 53 extends 
vertically across the rear portions of a plurality, two for example, of 
vertcailly adjacent bodies 2, 2, so that the two vertically connected 
display units 1, 1 can be handled as one unit during transportation. The 
support plate 51 has the same height as that of the connectors 53, 53 and 
fixed thereto, so that one support plate 51 supports four display units 1. 
The display units 1 are disposed horizontally adjacent to each other with 
substantially no gap therebetween and vertically spaced at small distances 
or intervals left therebetween. 
FIGS. 6 and 7 illustrate different ventilators positioned behind the 
vertical post 49 on which the display units 1 are supported. As shown in 
FIG. 6, the ventilator comprises a plurality of ventilator fans 55 and a 
louver 56 placed in front of the ventilator fans 55. The ventilator shown 
in FIG. 7 includes a single ventilator fan 57 located in a lower position, 
a hood or duct 58 for directing an upward stream of air from the 
ventilator fan 57 into a horizontal direction, and a stepped louver 59 
mounted in front openings in the duct 58. The air streams from the 
ventilator flow through the passages between the vertically spaced display 
units 1 in the directions of the arrows (FIGS. 6 and 7) to cool the 
sockets 17, the water-resistant packings 22, and the light-emitting 
elements 23. Since the lower panels 11 of the bodies 2 are inclined 
upwardly and rearwardly, as shown in FIG. 5, the air streams are guided by 
the sloping lower panels 11 smoothly into the passages between the display 
units 1. 
The ventilator fans 55, 57 may be rotated in a reverse direction to direct 
air flows in a direction opposite to that of the arrows shown in FIGS. 6 
and 7 through the passages between the display units 1. Thus, the sockets 
17, the water-resistant packings 22, and the light-emitting diodes 23 can 
also be cooled for heat radiation. This mode of operation is adavantageous 
in that the level of noise produced by the color display system and 
radiated into the surrounding environment can be reduced. 
The electric connector 32 of the signal inlet of a display unit 1 is 
connected to the electric connector 33 of the signal outlet of a 
horizontally adjacent display unit 1, so that electric signals can be fed 
horizontally from display unit to display unit. The vertically adjacent 
display units 1 are not electrically connected and hence there is no 
electric signal delivered vertically from display unit to display unit. 
Accordingly, there is required no cable for vertical signal transfer, and 
the wiring procedure for electrically connecting the display units 1 can 
be simplified. The electric connector 36 of the power supply inlet is 
connected to a power supply (described later on). The light-emitting 
elements 23 may be arranged in other patterns. For example, each 
three-primary emitting set may comprise two light-emitting elements 
capable of emitting blue light which is relatively weak in intensity, a 
single light-emitting element capable of emitting red light, and a single 
light-emitting element capable of emitting green light, the four 
light-emitting elements being positioned on the corners of a square. With 
this modified arrangement, the opposite sides of the body 2 may be 
vertical, rather than inclined at 60 degrees to the horizontal plane as 
illustrated. 
FIGS. 8 through 17 illustrate a color display system constructed in 
accordance with a second embodiment of the present invention. The color 
display system of the second embodiment is particularly suitable for use 
in an indoor arena or as a mobile display system on a large-size trailer. 
The color display system is composed of a plurality of display units 100 
each including a body 101 of synthetic resin comprising, as shown in FIGS. 
8 and 9, an upper chassis 102 and a lower chassis 103. The body 101 has on 
its front face a plurality of tubular casings 105 serving as outer shells 
of sockets 104, respectively. Two rows of light-emitting elements 106 
grouped as three-primary triads are horizontally mounted by the sockets 
104 in front end portions of the tubular casings 105. The light-emitting 
elements 106 are smaller in size than the light-emitting elements 23 
according to the preceding embodiment, but are arranged in the same 
pattern as that of the light-emitting elements 23. An annular 
water-resistant packing 107 of rubber is fitted over a front end of each 
of the tubular casings 105, with the light-emitting element 106 being 
inserted through the water-resistant packing 107 into the socket 104. 
As illustrated in FIG. 9, a control circuit unit 109 including a 
printed-circuit board 108 is housed in each body 101. The control circuit 
unit 109 is electrically connected by lead wires 110 to the sockets 104 
for controlling the light-emitting elements 106. The control circuit unit 
109 will later be described in detail. 
The body 101 supports on the rear portion thereof three electric connector 
means electrically connected to the control circuit unit 109 and to 
external terminals. The three electric connector means include, as shown 
in FIG. 11, a signal inlet composed of a cable 111 extending from the rear 
portion of the body 101 and an electric connector 112 attached to an outer 
end of the cable 111, a signal outlet composed of a cable 113 extending 
from the rear portion of the body 101 and an electric connector 114 
attached to an outer end of the cable 113, and a power supply inlet 
composed of a cable 115 extending from the rear portion of the body 101 
and an electric connector 116 attached to an outer end of the cable 115. 
As shown in FIG. 8, the body 101 has opposite sides 117, 118 inclined in 
conformity with the sides of opposite triads of light-emitting elements 
106, and any horizontally adjacent display units 100 are located as 
closely to each other as possible. The body 101 has rear side recesses 
101a, 101a defined behind the opposite sides 117, 118 so that the body 101 
can easily be supported in position as described later on. 
The tubular casing 105 has an upper portion projecting upwardly beyond an 
upper surface of the body 101, and a lower portion projecting downwardly 
beyond a lower surface of the body 101, for increased heat radiation 
through ventilation as described later on. As shown in FIGS. 8 and 9, a 
substantially L-shaped attachment 119 is fixed by screws to a rear upper 
surface of the body 101. 
FIGS. 10 through 13 show a support arrangement for the display units 100. 
The support arrangement comprises vertical posts 120 and support racks 
121. The posts 120 are positioned respectively in the rear side recesses 
101a in the bodies 101 of horizontally adjacent display units 100, 100. 
The horizontally adjacent display units 100 are secured to the posts 120 
by the support racks 121 fixed by screws 122 to opposite sides of the 
posts 120. Two symmetrical support racks 121 are employed as a pair 
capable of supporting a plurality (four for example) of vertically 
adjacent display units 100. As illustrated in FIG. 13, each of the suport 
racks 121 has upper and lower bent flanges 123, a plurality of vertically 
spaced partitions 124 disposed between the upper and lower flanges 123, 
and a rear bent flange 125. The display units 100 are guided at their rear 
portions between the flanges 123 and the partitions 124 when the display 
units 100 are inserted. After the display units 100 are inserted until the 
attachments 119 are held against the flange 125, screws 126 are threaded 
through the flange 125 into the attachment 119, thereby fastening the 
display units 100 to the support racks 121. The edges of each support rack 
121 which define the holes for the screws 122 are recessed away from the 
display unit 100 toward the post 120, so that the screws 122 have their 
heads disposed in the recessed portions out of interference with the 
display units 100 when the latter are slid along the support rack 121. 
With the foregoing support arrangement, the display units 100 are located 
in horizontally adjacent relation and spaced vertically with small 
distances or passages therebetween. 
The same ventilator as that shown in FIGS. 6 or 7 may be used with the 
color display system according to the second embodiment for passing air 
through the passages between the vertically arranged display units 100 to 
thereby cool the tubular casings 105, the water-resistant packings 107, 
and the light-emitting elements 106. The heat radiated by the display 
units 100 can effectively be dissipated from the portions of the tubular 
casings 105 which project upwardly and downwardly into the passages 
between the display units 100. Such a tubular construction can easily be 
achieved since the body 101 is molded of synthetic resin, and is 
advantageous in that the outer shells 105 of the sockets 104 that will be 
heated up to a high temperature can be formed with the body 101. The 
display units 100 have a relatively large depth, and would not be stably 
supported by rear supports. The support arrangement of the invention 
supports the sides of the display units 100 at the recesses 101a defined 
behind the opposite sides 117, 118 of the bodies 101. This allows the 
display units 100 to be stably supported in position. 
FIG. 14 shows a modified support arrangement composed of vertical posts 
120, channel-shaped auxiliary support members 128 fastened by screws to 
opposite sides of the vertical posts 120, and support racks 121 fixed by 
the auxiliary support members 128 to the vertical posts 120. 
According to still another modification shown in FIGS. 15 through 17, a 
support arrangement comprises vertical posts 120 disposed behind the 
horizontally adjacent display units 100 and aligned with their joints, 
arms 130 retractably extending through guides 129 of metal fixed to 
opposite sides of the posts 120, and support racks 121 secured to the 
sides of ends of the arms 130 and positioned in the rear side recesses 
101a in the bodies 101, the support racks 121 being fastened to the bodies 
101. As shown in FIG. 17, each guide 129 has four guide rollers 131 
rollingly supporting the upper and lower surfaces of one of the arms 130. 
When the arms 130 are in the most advanced position as shown in FIGS. 15 
and 17, stoppers 132 on the arms 130 are held against the rear ends of the 
guides 129 to keep the display units 100 in their normal position. When 
selected arms 130 are slid in a rearward direction, the display unit 100 
secured to the selected arms 130 is positioned rearward of the rear ends 
of the other adjacent display units 100 as shown in FIG. 16. In this 
position, the screws 126 may be removed and the display unit 100 may be 
slid forward out of the support racks 121 for servicing. This is 
advantageous in applications where the color display system is installed 
in an elevated position and hence cannot be serviced from the front face 
thereof. 
The display units 100 may directly be secured to the arms 130 without the 
intermediary of the support racks 121. In the support arrangement shown in 
FIG. 11, the display units 100 may also directly be attached to the posts 
120. Similarly, in the support arrangement of FIG. 14, the display units 
100 may directly be attached to the auxiliary support members 128. 
However, use of the support racks 121 is more advantageous in that a 
plurality of display units 100 can be transported as one unit since they 
are supported together by the support racks 121, 121 secured thereto by 
the screws 126. 
The body 101 is assembled by combining the upper and lower chassis 102, 
103, fastening them with screws, and applying a caulking material to the 
joints of the upper and lower chassis 102, 103. For electric connection, 
the electric connector 112 of the signal inlet of one display unit 100 is 
connected to the electric connector 114 of the signal outlet of a 
horizontally adjacent display unit 100. Vertically stacked display units 
100 are not electrically interconnected. 
FIG. 18 shows an electric wiring arrangement for the color display system 
of the first embodiment in which the display units 1 are arranged as a 
matrix in horizontal rows and vertical columns, the display units 1 being 
electrically connected. In each horizontal row of display units 1, 
electric signals are supplied from a signal inlet cable 31 (shown at a 
righthand end) to the display unit 1 connected thereto. The signals are 
then fed from the electric connectors 33 of the display unit 1 over a next 
cable 31 to a following display unit 1. Likewise, the signals are 
delivered through the succession of display units 1 until the signals 
reach the display unit 1 at the lefthand end. The signal delivery cables 
31 are interconnected only between the horizontally arrayed display units 
1, and not between the vertically arrayed display units 1. Accordingly, 
the electric connection between the display units 1 is relatively simple 
and easy to perform. The cables 35 extending as the power supply inlets 
from the display units 1 are all connected to a power supply 200. The 
display units 100 according to the second embodiment are electrically 
connected in the same pattern as that shown in FIG. 18. 
FIG. 19 is a block diagram of the control circuit unit 27 (109). There are 
employed five types of electric signals; three R, G, B signals which are 
pulse-width modulated, a shift pulse signal, and a latch pulse signal. The 
five signals delivered from the cables 31 (111) are fed through the input 
buffer 201 into the display unit 1 (100). Except for the latch and shift 
pulse sigals, the R, G, B signals are delivered through a plurality of 
shift registers 202 to an output buffer 203. The latch and shift pulse 
signals and the R, G, B signals are then issued from the output buffer 203 
over the cables 31 (113) to a next display unit 1. The shift registers 202 
serve to shift the R, G, B signals and apply their output signals through 
latches 204 to drivers 205 for driving the light-emitting elements 23 
(106) with pulse-width modulated signals to display images or patterns in 
desired color tones. The shift pulse signal as it is fed from the input 
buffer 201 is applied to each of the shift registers 202 for enabling the 
latter to shift the R, G, B signals. The latch pulse signal as it is fed 
from the input buffer 201 is applied to each of the latches 204 to latch 
the R, G, B signals. The input and output buffers 201, 203 may be 
dispensed with in the control circuit unit 27 (109). 
The basic arrangement of the color display systems according to the present 
invention has the following advantages: 
(1) Each display unit has two rows of light-emitting elements mounted in 
respective sockets disposed on the front face of a display unit body, the 
light-emitting elements being capable of emitting light of three primary 
colors and grouped as triads horizontally arrayed across the two rows of 
light-emitting elements. Thus, each display unit has triads of 
three-primary light-emitting elements with signal lines connected to the 
triads being bunched up in the display unit. Accordingly, the procedure 
for laying and connecting the signal lines is facilitated by the 
appropriately unitized display units. 
(2) The control circuit unit with the printed-circuit board electrically 
connected to the sockets for controlling the light-emitting elements is 
accommodated in the body of each display unit. The control circuit unit is 
electrically connected to the sockets within the display unit body without 
requiring any outside cables for connection to the sockets. This keeps the 
required cables for connection to external sources or terminals to a 
minimum, so that the operation for laying and connecting the cables is 
simplified at the time the color display system is installed. The wiring 
construction needs substantially no space or only a small space for the 
cables, and contritutes to a reduction in the installation cost. 
(3) The display units are vertically spaced with small gaps or passages 
left therebetween for admission therethrough of air supplied from the 
ventilator to cool the sockets and light-emitting elements arranged in two 
rows on each display unit. Consequently, the sockets and light-emitting 
elements are kept at a relatively low temperature during operation of the 
color display system, and hence will have a higher reliability and a 
longer service life. Since the cables need only a small installation space 
at most, a sufficient space is available for installing the ventilator 
therein behind the display units. As there is no control circuit unit 
disposed outside and rearward of each dislay unit, the ventilator can be 
located as closely to the display units as possible for an increased 
ventilation effect. 
Although certain preferred embodiments of the present invention have been 
shown and described in detail, it should be understood that various 
changes and modifications may be made therein without departing from the 
scope of the appended claims.