US3340637A

US3340637A - Status display assembly

Info

Publication number: US3340637A
Application number: US386882A
Authority: US
Inventors: Floyd L Campbell; Ralph W Wight
Original assignee: TECHNICAL PRODUCTS ENGINEERING
Current assignee: TECHNICAL PRODUCTS ENGINEERING; TECHNICAL PRODUCTS ENGINEERING Co
Priority date: 1964-08-03
Filing date: 1964-08-03
Publication date: 1967-09-12
Anticipated expiration: 1984-09-12

Description

ep 1 1967 F CAMPBELL ETAL 3,340,637

STATUS DISPLAY ASSEMBLY Filed Aug. 3, 1964 I 2 Sheets-Sheet l Z J /2a l05 INVENTORS Flora L. CAMPBELL, 56 /00 m2 RALPH //1/. W/GHT 9.2 95 5y THE/Q ATTORNEYS HARE/5, K/Ech', Puss/ELL & KER/v United States Patent fornia Filed Aug. 3, 1964, Ser. No. 386,882 11 Claims. (Cl. 40-130) This invention relates generally to communication control systems and more particularly to a status display system and provides improvements in status display boards and equipment associated therewith.

Status display systems are used in visual control and are commonly employed by police departments, fire departments, civil defense control units, hotels, vehicle dispatchers, pipeline operations, and many other applications. The status display board may frame a map, a series of numbers, circuitry such as that of a telephone system, and other subject matters susceptible to visual display for control purposes. The intelligence displayed need not be limited to that enumerated but may be any information which is desirably continuously displayed for visual regulation.

A typical status display board or panel heretofore employed has a frontal glass or rigid plastic sheet or pane with which the intelligence to be displayed is closely associated; for example, a map of an area in the form of a light transmitting sheet placed immediately behind the frontal pane- Signal lamps are positioned within an egg crate bafile structure immediately behind the frontal pane and map. Alternatively, the map or other intelligence may be etched or imprinted on the frontal pane itself. Individual lamps are located within the compartments of an egg crate structure with the bafiiing serving to shield against lateral diffusion of light behind the display panel pane. Commonly, the lamps employed require watts or more of power and will light a relatively large area of the display panel. A typical egg crate structure provides approximately two inch or larger square compartments with a permanent socket and lamp located centrally thereof. With this arrangement, there is a definite limitation on the accuracy with which a specific point may be located as to the many sites of the display map, since with the use of the egg crate baffling structure of the conventional display panel, the entire enclosed area of each compartment of the egg crate structure is lighted, resulting in an indefinite signal location. This limits pin pointing sites.

It is a principal object of the invention to provide an improved status display board or panel permitting more precise location of signals than heretofore possible.

It is a further object of the invention to provide a status display board which permits a ready interchange of the subject displayed.

It is a still further object of the invention to provide a status display board that is flexible in its use with various electrical information sources.

It is a further object of the invention to provide a status display board characterized by a minimum of glare and a board in which the signals are in focus with little lateral emanation of light.

It is another object of the invention to provide a status display board capable of providing many more signal sites than are characteristic of display boards heretofore em ployed.

It is a still further object of the invention to provide a status display board wherein the structure of the board behind the frontal pane is hidden from view.

It is another object of the invention to provide a status display board having greatly reduced power requirements.

It is another object of the invention to provide a status display board which readily dissipates the heat of the signal lamps.

It is a still further object of the invention to provide a display board of a structure which permits the use of many more lamps per unit area than heretofore possible.

It is a still further object of the invention to provide lamp holders which are movable from site to site without the use of tools.

It is a still further object of the invention to provide a status display board which is accessible from the front as well as the back for changing the location of the various signal sites.

In the status display board of the invention there is provided a rigid, flat grid or grating structure behind and paralleling a transparent frontal pane and closely spaced therefrom. The grid structure has a plurality of lamp holder receiving slots or openings, preferably rec-.

tangular, but other shapes of openings may be conveniently employed in some applications. The lamp holders used in the status display board of the device are removably held within their respective openings and are readily removed therefrom and transferred to other sites. In a preferred embodiment of the invention means are provided for moving the grid structure toward and away from the transparent frontal pane and the lamp holders are also provided with means permitting movement of the lamps toward and away from the frontal pane.

The lamps used in the status display board of the invention are preferably elongated and are movably held within their respective lamp holders with their longitudinal axes substantially perpendicular to the frontal pane and means are provided for limiting emanation of light to the end of the elongated lamp which is adjacent the frontal pane. For example, in a preferred embodiment the elongated lamp structure at its light emanating end has a lens with a guard or blind thereabout which substantially eliminates lateral extension of the rays of light. This provision, together with the location of the light emanating end of the lamp adjacent to the frontal pane, assures a sharper focus, permits the use of a smaller lamp, and hence more precise location of the signal site.

In a preferred embodiment, a cylindrical lamp having an end lens of a diameter 7 to inch is used.

The status display board of the invention in its preferred form has the intelligence whether it be a map or other information provided on a thin, flexible translucent but not transparent plastic sheet and this sheet is located immediately adjacent and in contactwith the inner face of the transparent frontal pane. The light emanating ends of the respective lamps are located immediately adjacent the translucent plastic sheet and preferably in contact therewith. The provision of the translucent plastic sheet is a special feature of the status display board of the invention and not only does it serve to hide the structure of the display board behind the frontal pane but it has been found to minimize diffusion of light and to give an even more precise location for each signal site. There is substantially no diffusion of light laterally with joint use of the translucent plastic sheet and the use of lamps which have their light emanation limited to an end immediately adjacent the translucent plastic sheet. In some forms of the invention no intelligence or other information is provided on the thin translucent sheet. The sheet serves only to hide the mechanical structures behind it, While the intelligence or other information is applied by various means to either the front or rear side of the frontal pane.

In one form of the status display board of the invention, the grid is hinged to provide for outward swinging (after first removal of the frontal pane) and thus permit access from the front of the device to the rear of the grid structure for relocation of the signal lamps in their respective lamp holders.

The display panel board of the invention is not limited to use with any particular means for supplying electrical information. However, the display panel is particularly useful with a system employing IBM type cards wherein information concerning events that are desired to be continuously displayed is received by an operator or dispatcher and recorded on an IBM type card. The card is then inserted into a suitable electronic device and there results an illumination of the lamp of the display board applicable to the situation.

Other objects and advantages of the invention will become apparent to those skilled in the art upon reference to the accompanying specification and drawings which disclose presently preferred forms of the structure of the invention.

In the drawings:

FIG. 1 is a perspective view of a preferred embodiment of the status display system of the invention including a wall mounted status display board;

FIG. 2 is a longitudinal sectional view taken along line 22 of FIG. 1 illustrating in considerable detail the structure of the status display board;

FIG. 3 is a horizontal sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a side elevational view of one embodiment of a lamp holder suitable for use with the status display board of FIGS. l3 inclusive;

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 4;

FIG. 6 is a side elevational view of another and preferred embodiment of a lamp holder suitable for use with the display board;

FIG. 7 is a fragmentary sectional view, partially in elevation, illustrating the lamp holder of FIG. 6 positioned within the status display board; and

FIG. 8 is a fragmentary, side elevational view of the lamp supporting grid of the status display board of the invention.

There is illustrated in FIG. 1 a status display system made up of a wall mounted status display board or panel 10 and a console 12 comprising a desk 14, an IBM card control unit 16 for regulation of the status display board 10, a remote control unit 18, and a microphone 20.

The status display board or panel 10 of the invention includes a cabinet 24 fixed to the wall above the console 12. The lower portion of the cabinet 24 has an enclosed area or compartment 26 which includes a terminal block support 28 with the compartment being closed at its front by a removable cover 30 which is held in place by bolts 32.

The front of the status display board 10 is closed by a removable door 36 which is pivotally attached to the cabinet 24 at its upper end by pins 38 resting in door brackets 40 mounted at the outside top of the cabinet. The door 36 at its lower end is provided at its opposite sides with handles 44 which are fixed to a rectangular door frame 46. The door frame 46 has fixed to its inner face a rectangular, transparent, rigid, frontal pane 48 by several screws 50. The frontal pane 48 is preferably formed of a rigid, clear plastic material such as Lucite; however, glass may be employed. The heads of the screws 50 are recessed so as not to interfere with the clinging of a flexible plastic sheet 52 to the inner face of the frontal pane 48. The plastic sheet 52, which may take the form of a city map or other intelligence, is supported at its upper end by a map retaining clamp 56 which is held by screws to the upper backside of the frontal pane 48. The plastic sheet 52 hangs freely from the map retaining clamp 56 and normally is held by a static charge to the inner face of the frontal pane 48. In a preferred embodiment the plastic sheet 52 is' a commercially-available processed translucent polyester film.

When it is desired to remove the door 36 from the status display board to gain access to the interior thereof, retaining screws 60 above and to the outside of the handles 44 are removed. The door 36 is then swung upwardly and lifted out of the brackets 44 and thereby wholly removed from the cabinet 24. The door 36 may be hinged along a vertical edge to swing laterally out of the way.

It is a special feature of the status display board of the invention to provide a rigid, flat, metal grid 64 having a plurality of lamp holder receiving slots 66 closely spaced to and paralleling the frontal pane 48 of the door 36. The grid is preferably formed of stamped metal which metal serves as a heat sink for the lamps and thus assists in the dissipation of heat. As perhaps most clearly seen in thecut-away area of the status display board of FIG. 1, and also in FIG. 3, the grid 64 in the particular embodiment illustrated is divided vertically into two

members

68 and 70. The respective grid halves 68 and 7 0 are carried by grid support frame assemblies 74. Each frame assembly 74 comprises a U-shaped channel member 76 forming a three-sided frame which is pivotally supported at its outer front edge by a vertically extending, elongated, piano-type hinge 78 to the interior frame of the cabinet 24. With this means of mounting, it will be seen that the respective grid halves 68 and 70, upon removal of the frontal door 76 may be swung respectively and individually in an outward direction to give access to the rear side of the grid 64.

Each of the grid support frame assemblies 74 of the respective grid halves 68 and 70 has vertically extending angle iron supports 79 held to its rear face. Adjustable grid support rods or studs 80 support or hold the grid halves 68 and 70 to their respective grid support frame assemblies 74. The opposite ends of the grid support rods 80 are threaded and passed through tapped holes in the grid 64 at one end thereof and at the other end through the frame assembly 74 and vertical angle iron supports 79. Lock nuts 82 may be loosened to move the grid supports rods and the grid carried thereby toward and away from the paralleling frontal pane 48. It will be noted that the grid support rods at the upper and lower ends of the grid support frame assembly are of heavier structure than that of the intermediate support rods 80 because of the weight carried by the former.

The rear wall of the cabinet 24 carries a cable support bar 84 from which wires emanate (not shown for purposes of clarity) connecting to several lamps 88 which, in the particular embodiment illustrated in FIGS. 1-3, are supported in lamp holders 90 in batteries of three. A lamp holder 90 will occupy a single slot 66 of the grid 64.

The particular lamp holder 90 illustrated in FIGS. 1-3 is seen in enlarged detail in FIGS. 4-5. The lamp holder 90- has along its lower edge an elongated offset flange 92 and along its upper edge three spaced forwardly extending spring element locking flanges 94. The latter locking flanges 94 include a horizontally extending section 94a and integral with the forward end thereof an upwardly and downwardly turned section 94b. The particular lamp holder 90 illustrated is designed to hold three lamps 88 side-by-side with the respective lamps extending through apertures of the main body 98 of the holder. The body 98 is sized to fit snugly within a slot 66. In the insertion of the lamp holder 90 illustrated in FIGS. 4 and 5 into the grid 64, which lamp holder is preferably formed of metal, the offset flange 92 is placed through a slot 66 from the rear side of the grid 64 and the top portion of the holder is then forced forwardly with the locking flange 94 being depressed downwardly and then snapping up into the position illustrated in FIG. 5 to lock the lamp holder in position. To remove the holder from the slot, the spring element locking flanges 94 are depressed and the holder forced backward, pivoting about the offset flange 92 during the'removal. It will be seen that the lamps 88, which are cylindrical, are fixed in position by a split friction clamp 100 which may be opened by forcing outwardly extending lugs 102 apart, thus permitting movement of the lamps within the holder.

The particular lamp holder 90 illustrated in FIGS. 4 and 5 is provided with three colored lamps; namely, yellow, red and green, which may be used to indicate varying statuses at a particular site on a map. It will be appreciated that in some applications a single lamp or perhaps two lamps will be employed in the holder.

Another and a presently preferred form of the removable lamp holder for use in the grid 64 is illustrated in FIGS. 6 and 7. The holder 104 is formed of a pliable plastic material such as heavy polyethylene and includes a rectangular body 106 sized to fit into a slot 66 and snugly fill said slot. The body 106 has on one face an integral perpendicularly extending sleeve 108 and is provided with means for removably retaining the rectangular body 106 within a slot 66 of the grid 64 in which it may be placed. It will be seen that the perpendicularly extending sleeve 108 at its free end is provided with a slot 110 extending toward the rectangular body 106. This slot 110- with positioning of the removable lamp holder 104 in a slot 66 tends to close so as to bring about a more snug engagement between the sleeve 108 and a lamp 112 slidably held within the sleeve. More particularly, the means for removably retaining the lamp holder within a slot '66 comprises in the particular embodiment illustrated in FIGS. 6 and 7 two

rearwardly extending flanges

116 and 118. The lamp holder of FIGS. 6 and 7 is inserted in the grid 64 from the rear side thereof. The flange 116 has a first portion 11611 perpendicular to the main body of the holder, which first portion 11611 has an outside surface engageable with the edge of the slot 66 in which the holder may be placed. An upturned second portion 116b is integrally formed with the trailing edge of the first portion of the flange 116, which upturned second portion engages the grid structure about the slot 66. The other flange 118 before insertion in the grid is disposed at a slight, outwardly extending angle to the main rectangular body of the lamp holder. The flange 118 is flexible inwardly to permit a forward portion or cut-out area 11% to engage an edge of the slot as illustrated in FIG. 7, thereby removably holding the lamp holder within the slot. The main rectangular body 106 of the lamp holder 104 is sized to snugly engage the edges of a slot when placed therein. The

flanges

116 and 118 are provided respectively with two, spaced raised and small protuberances or pimples 116a and 118c immediately adjoining the rectangular body 106. The protuberances 1160 and 1180 engage the outside face of the grid about the opening and help to retain the holder 104 in place.

The lamps employed in the lamp holders of the status board of the invention are preferably elongated and are movably held within their respective lamp holders with their longitudinal axes substantially perpendicular to the frontal pane 48 and are movable lengthwise of their respective longitudinal axes. The lamps are generally cylindrical and preferably are provided with means limiting emanation of light to the end of the lamp adjacent the frontal pane. In the lamps illustrated in FIGS. 5-7, inclusive, the means for limiting lateral emanation of light comprises an opaque guard member 126 placed about an end lens 127 (FIG. 5) and a similar but somewhat differently shaped opaque ring guard 128 in the lamps of FIGS. 6 and 7. The lamps are desirably of one watt capacity. The bases of the lamps of FIGS. 5 and 6 respectively are provided with

prongs

103 and 105 which are adapted to receive receptacles 107 as illustrated in FIG. 7.

As best seen in FIG. 7, the outer, light emanating end of the lamp engages the translucent sheet or map 52, pressing it against the frontal pane 48. The lamp holder illustrated in FIGS. 6 and 7 may include one or more lamps as does the holder described and illustrated in FIGS. 4-5.

Desirably the frontal pane 48 has its outer surface treated with a substance which reduces glare and more readily permits marking thereon as illustrated in the status display board of FIG. 1 to form numbered areas over the map of the translucent sheet 52. The surface is sprayed with a lightly pigmented vinyl solution, or may be lightly sandblasted, etched or otherwise treated to render less reflective.

The slots 66 of the grid 64 may take various forms but are conveniently rectangular and may be sized, preferably to small dimensions, to meet the needs of the particular application.

It will be seen that in the foregoing described structure, the respective lamps are adjustable in either of two fashions; by movement within their respective holders, and secondly by movement of the grid 64 forward or toward the frontal pane 48.

A convenient way of locating the lamps 112 of the lamp holders 104 in contact with the inner face of the translucent sheet 52 may be achieved in the following manner. A generally rough location of the grid 64, lamp holders 104, and lamps 112 with reference to the translucent sheet 52 and frontal pane 48 is had by adjustment of the grid adjusting rods to move the grid toward or away from the frontal pane 48 as required. The lamps 112 are located forwardly within their respective holders 104 as shown in FIG. 6. The respective grid halves 68 and 70 are swung into their closed positions as illustrated in FIG. 2 with the back side of the grid support frame assembly engaging a rubber shim 101 carried by a bracket member 99 of the cabinet 24. The door 36 containing the frontal pane 48 is then hung from the door brackets 40 of the cabinet 24 and lowered into position. The door 36 upon reaching its closed position will press the lamps 112 backward if they be too far extended through engagement of the heads of the lamps 112 and the translucent sheet 52 which backs against the frontal pane 48.

In operation, the dispatcher or operator, upon receiving information in the particular system illustrated in FIG. 1 records that information on a card 109 and inserts it into the card control unit 16 which causes the appropriate lamp to light behind the tranlucent map sheet 52 of the status display board.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

We claim:

1. In a status display board of the type having a rigid transparent frontal pane with intelligence associated therewith and viewable from the front side thereof and a plurality of display lamps located behind the transparent frontal pane, the improvement comprising:

a rigid open grid structure paralleling the transparent frontal pane and closely spaced therefrom, said grid structure having a plurality of lamp holder receiving slots;

lamp holders removably held within the slots of the grid structure, said lamp holders having means permitting movement of the lamps relative to the holders toward and away from said frontal pane; and

lamps movably held within said lamp holders.

2. In a status display board of the type having a rigid transparent frontal pane with intelligence associated therewith and viewable from the front side thereof and a plurality of display lamps located behind the transparent frontal pane, the improvement comprising:

a rigid grid structure paralleling the transparent frontal pane and closely spaced therefrom, said grid structure having a plurality of lamp holder receiving slots;

a lamp holder removably held within a slot of the grid structure, said lamp holder having means permitting movement of a lamp within the holder toward and away from said frontal pane; and

an elongated lamp having an end adjacent the frontal panel and movably held within the lamp holder with its longitudinal axis substantially perpendicular to the frontal pane and movable lengthwise to said axis between a position in which said end is against the pane and a position in which the end is spaced therefrom, said lamp having means limiting emanation of light to the end adjacent the frontal pane.

3. In a status display board of the type having a rigid transparent frontal pane with intelligence associated therewith and viewable from the front side thereof and a plurality of display lamps located behind the transparent frontal pane, the improvement comprising:

a lamp holder removably held within a slot of the grid structure, said lamp holder having means permitting movement of a lamp within the structure toward and away from said frontal pane and including a body portion snugly filling the slot with an integral rearwardly extending open-ended sleeve adapted to receive the lamp; and

an elongated lamp movably held within the sleeve of the lamp holder with its longitudinal axis substantially perpendicular to the solid frontal pane and movable lengthwise of said axis, said lamp having means limiting emanation of light to the end thereof adjoining the frontal pane.

4. In a status display board, the structure comprising:

a rigid transparent frontal pane;

a thin translucent plastic sheet, said sheet being immediately adjacent the inner face of the rigid transparent frontal pane;

a rigid grid structure paralleling the plastic sheet and closely spaced therefrom, said grid structure having a plurality of lamp holder receiving slots;

a lamp holder removably held within a slot of the grid structure, said lamp holder having means for movably holding a lamp therein and permitting its movement relative to the holder into contact with the back of the translucent sheet; and

an elongated lamp movably held within the lamp holder with its longitudinal axis perpendicular to the frontal pane and movable lengthwise of said axis, said lamp having means limiting emanation of light to the end adjacent the translucent plastic sheet.

5. In a status display board, the structure comprising:

a rigid transparent plastic frontal pane having an outer nonglare surface upon which markings may be applied;

a thin translucent plastic sheet with intelligence imprinted thereon, said sheet being immediately adjacent the inner face of the rigid transparent frontal pane;

a rigid grid structure paralleling the solid transparent frontal pane and closely spaced from said translucent plastic sheet, said structure having a plurality of rectangular lamp holder receiving slots;

a lamp holder removably held within an opening of the grid structure, said lamp holder having means permitting movement of the lamp relative thereto and toward the transparent frontal pane and into contact with the translucent plastic sheet; and

an elongated lamp held within the lamp holder with its longitudinal axis substantially perpendicular to the frontal pane and movable lengthwise thereof, said lamp being generally cylindrical and having means limiting emanation of light to the end thereof adjacent the translucent plastic sheet.

6. In a status display board, the structure comprising:

a rigid transparent frontal pane;

thin translucent plastic sheet with intelligence imprinted thereon, said sheet being immediately adjacent the inner face of the rigid transparent frontal pane;

a rigid grid structure paralleling the translucent sheet and closely spaced therefrom, said grid structure having a plurality of lamp holder receiving slots;

a lamp holder removably held within a slot of the grid structure and including a body portion snugly filling the slot with an integral rearwardly extending sleeve adapted to movably receive a lamp and permit its movement into contact with the back of the translucent sheet; and

an elongated lamp movably held in the sleeve of the lamp holder with its longitudinal axis perpendicular to the frontal sheet and movable lengthwise of said axis, said lamp being generally cylindrical and having means limiting emanation of light to the end adjacent the translucent plastic sheet.

7. In a status display board, the structure comprising:

a rigid transparent plastic frontal pane;

a thin translucent plastic sheet with intelligence imprinted thereon, said sheet being immediately adjacent the inner face of the solid transparent frontal pane;

rigid grid structure paralleling the solid transparent frontal pane and closely spaced from said translucent plastic sheet, said structure having a plurality of lamp holder receiving slots;

a lamp holder removably held within a slot of the grid structure and including a body portion with an integral rearwardly extending open-ended sleeve adapted to receive and slidably hold a lamp and permit movement of said lamp toward the transparent frontal pane and into contact with the translucent plastic sheet; and

an elongated lamp slidably held within the sleeve of the lamp holder with its longitudinal axis substantially perpendicular to the frontal pane and movable lengthwise thereof, said lamp having means limiting emanation of light to the end thereof adjacent the translucent plastic sheet.

8. A removable lamp holder for elongated cylindrical lamps for use with a rigid grid having openings, said lamp holder comprising an integral structure formed of a resilient plastic material including a body with opposed faces sized to fit into an opening of the grid and having on one face thereof a perpendicularly extending openended sleeve to slidably receive a lamp, said body snugly filling the grid opening when inserted therein, and means for removably retaining the body within said slot.

9. A lamp holder as defined in claim 8 wherein the perpendicularly extending sleeve has a slot at its free end to provide for the enlargement of said free end upon insertion of a lamp therein, which slot extends toward said body.

10. A removable lamp holder for elongated cylindrical lamps for use with a rigid grid having rectangular slots, said lamp holder comprising an integral structure formed of .a resilient plastic material including a rectangular body of substantially the same dimensions as the slots of the grid and having on its rear face a rearwardly extending open-ended sleeve sized to slidably receive a lamp, said rectangular body snugly filling the slot when inserted therein and having integrally formed therewith first and second rearwardly extending flanges respectively at the upper and lower edges of said rectangular body, one of said flanges having a first portion substantially perpendicular to the body, which first portion has an outside surface engageable with the edge of the slot and an upturned second portion adjacent the rear edge thereof for engaging the grid structure about the slot and said other one of the flanges being disposed at a slight outwardly extending angle to said rectangular body, said other one of the flanges being flexible inwardly to permit a forward shoul body.

References Cited UNITED STATES PATENTS Camiener 339-126 X Linton 240l51 X Elliott 40132 X Johnson 40132 Roberts et al. 40132 Stark 240152 X FOREIGN PATENTS Australia. France.

Great Britain. Great Britain. Great Britain.

Light Receptacle, by W. L. Larrabee, February 1959.

15 LAWRENCE CHARLES, Primary Examiner.

HERBERT F. ROSS, EUGENE R. CAPOZIO, Examiners.

Claims

1. IN A STATUS DISPLAY BOARD OF THE TYPE HAVING A RIGID TRANSPARENT FRONTAL PANE WITH INTELLIGENCE ASSOCIATED THEREWITH AND VIEWABLE FROM THE FRONT SIDE THEREOF AND A PLURALITY OF DISPLAY LAMPS LOCATED BEHIND THE TRANSPARENT FRONTAL PANE, THE IMPROVEMENT COMPRISING: A RIGID OPEN GRID STRUCTURE PARALLELING THE TRANSPARENT FRONTAL PANE AND CLOSELY SPACED THEREFROM, SAID GRID STRUCTURE HAVING A PLURALITY OF LAMP HOLDER RECEIVING SLOTS; LAMPS HOLDERS REMOVABLY HELD WITHIN THE SLOTS OF THE GRID STRUCTURE, SAID LAMP HOLDERS HAVING MEANS PER-