US1971281A - Display device - Google Patents

Description

F. J. -SFRAC-UE DISPLAY DEVICE Aug.v 21, 1934.

4 Sheets-Sheet l Filed Jan. 30, 1933 'LJ A ljZ/ /Z Aug. 21, 1934. F. J. sPRAGUE DISPLAY DEVICE 4 Sheets-Sheet 2 1 7- /ZZ-Zjg.

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Filed Jan. :5o. 193s Allg. 21, 17934. 1 SPRAGUE l 1,971,281

` l DISPLM(` DEvIcE Filed Jan. so, 193s 4sheets-sneet 5 [NI/EN TOR.

Aug. 2l, 1934. F. J. SPRAGUE 1,971,281

, DISPLAY DEVICE Filed Jan. so, 195s 4 sheets-'sheet 4 ATTORNEYS.

Patented Aug. 21, 1934 UNITED lSTATES DISPLAY DEVICE Frank J. Sprague, New York, N. Y.

Application January 30, 1933, Serial No. 654,319

i 1s claims. (ci. 4c-s4) My invention relates to a novel display device as well as to a method of operation, by which a plurality of display members, for instance, lithographed posters, photographs or other forms of advertisements are made up into an assembly and are successively displayed in an opening or window of the casing of the display device.

I shall describe my invention on hand of a preferred embodiment, which consists of a sectionized elastic belt or band made up of a series of individual and independent display units, each of which includes a carrier provided with guide extensions, and` with a freely turning l5 spring-biased roller to which the display member, for instance, a poster, is detachably anchored with one of its ends. When the different units are assembled into a band the free end of each poster is detachably locked to the carrier of the next unit in advance, or'in the rear.

The housing of the display device is providedV on the inside of each of the two opposing sides with tracks of likecontour, in which tracks the guide extensions of the display units are properly guided. The tracks preferably form loops in which the display units arespaced with `the postersv in rolled up, or partly or fully unwound condition `depending on the position of their units in the tracks.

'I'he units may be removed or inserted from either the front or the back of the display device, and the number of units can be increasedl or decreased within the maximum and minimum capacity of the track, whereby the display band will automatically adiust itself to the number of units installed.

The displays may be progressed continuously, but preferably by interruptedfadvance past the frontal window or frame, and while before the window the posters unroll from their roller and when fully unro'lled before the display window the poster is stopped, although the driving mechanism and driving members for the carriers are rotating at continuous speed.

For the advance of the carrier members I provide preferably carrier Vchains mounted on the two opposing sides of the housing of the display device and close to the tracks. The chains are suitably driven by motor and intermediate driving members, and carry pick-up links which engage the carriers of the units for their passage before the display window and disengage the car riers after they have passed the Window.

My novel display device comprises various important advantages, for instance, standard advertising posters may be used. The number of posters can be varied between the maximum and minimum capacity of the device.

The insertion and removal of one or all of the units requires but little time and skill.

My novel device comprisesfew, simple and rugged parts, can be manufactured at comparatively low cost, and the mechanism requires practically no servicing.

The"whole device forms a self-contained unit f and the insertion and removal of the units can take place by opening the display window carrying front frame of the housing.

'I'he device can be manufactured in various sizes whereby to a great extent the same standard parts can be lused also for different sizes.

Except for the poster` and for the carrier bar, which may also be provided with advertising matterno part of the device passes the display window, and the printed matter of the displays appears before the window in such a manner that the successive lines can be read in the natural way.

The poster can be conveniently and efficiently illuminated from the inside and no part ofI the device falls between the light source and the poster.

Various other novel features and advantages of my invention will appear as the specification progresses. l 4

In the drawings vforming part of the specication:

Figure 1 is a front view, partly broken away, of a sign display device according to my invention.

Fig. 2 is a section of Fig. 1 along the line 2 2.

Fig. 3 is an enlarged section, partly broken away, of Fig.Y 1, along the line 3 3.

Fig. 4 is a partly broken away, enlarged View of the right front end of Fig. 1.

Fig. 5 is a front view of a display unit with its poster unwound and connected to the carrier of the preceding unit.

Fig. 6 is a side view of Fig. 5.

Fig. 'l is a side view of the display unit seen from the left. l

Fig. 8 is a fractional perspective view of the upper end of the poster.

Fig. 9 is a fractional perspective view of the lower end of a poster.

Fig. 10 is a perspective view partly broken away of the poster roller.

Fig. 11 is a side view of a pick-up link.

Fig. 12 is a front view of Fig. 11.

Fig. 13 is a side view of aretarding link.

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Fig. 14 is a front view of Fig. 13.

Fig. 15 is a side view partly in section and partly broken away of the poster roller.

Referring to Figs. 1 to 4 the display device cornprises a metal housing 1 having two sides l0-10, a top 2, bottom 3, a removable front 4 and a back 5. The housing when closed, offers a substantially dust-proof protection for the operating parts of the device, all of which fall within the housing.

The front 4 comprises a vertically hinged frame 6 provided with a window 7 of transparent material, for instance of glass, theA dimensions of which correspond to those of the displays. If desired the frame 6 may be an ornamental frame, but I prefer to provide a plain metal frame for the housing proper and provide a separate ornamental frame which covers either only the front or also partly or fully the sides of the housing.

The sides 10-10 are tied together at the top by rods 11 and l1 and at the bottom by rods 12 and 12', the rods being secured to the sides 10 by means of screws or in other suitable way.

Centrally located with respect to the front and the rear of the casing are an upper and a lower transverse shaft l6 and 17 respectively, carried in suitable bearings 15 provided on the sides l0-10 (see Fig 4).

Close to each of their ends, each of the shafts 16 and 1'7 carries sprockets 20-20, preferably spaced from the sides 10-10 by suitable washers.

The two left-hand and the two right-hand sprockets 20-20 are interconnected by a pair of synchronized chains 21-21, inside guides' 22-22 being provided to guide the straight portions of the chains.

Each chain is provided with a pick-up link 23 (see Figs. 3, 11 and 12) the two pick-up links being provided on corresponding portions of the The tow chains to form a complementary pair. pick-up links comprise xed pawls 24 which extend outwardly from the chain.

Preceding the pick-up links in the direction of travel of the chains are provided one or two pairs of retarding links 25 (see Figs. 3, 13 and 14). The retarding links are provided with a stop 28 and with a pivoted tongue 26 which is normally pressed against the stop -28 by means of a spring 27.

The tongue 26 projects outwardly I'from the chain and when pressure is exerted on the tongue 26 from its side facing the spring 27 the tongue is pressed against the stop and then assumes the position indicated in Fig. 13 in full lines; however, if pressure is exerted on the tongue from the other side the tongue assumes the position indicated in Figs. 13 and 14 in dotted lines. It should be noted that the tongues 26 of the re tarding links 25 are longer than the pawls 24 of the pick-up links 23. The reason therefor will appear later on.

A plate 30 carrying the light source or light sources and also acting as a reilector, is secured to the sides 10-10, the plate 30 being parallel with the front and back of the housing and is disposed intermediate between the two chains 21-21 preferably closer to the back than to the front of the housing. The plate 30 is preferably coated with a light-reecting coating 31, for instance with a coating of white enamel. The plate 30 carries suitable light sources, for 'instance, incandescent lamps 34 which arejinserted in suitable sockets 32 secured to the plate 30. g

In the drawings seven vertically-mounted lamps 34 are shown, so spaced 'as to obtain a substanievinei tially uniform illumination of the light transparent display. Electric connections are provided for the lamps through 32 and 33 and the lamp circuits may'be suitably controlled by switches or other control means. l

For the driving of the sprockets 20 suitable driving means are provided. In the device illustrated two motors M1 and M2 are provided which arev vertically mounted on the sides 10-10 above the shaft 17 and centrally disposed with respect to the chains 21-21. The shaft 35 of each of the motors is provided with a worm 36 which matches with a worm gear 37 rotatively carried on a horizontal stud 38 mounted on the corresponding side 10 (see Fig. 4). Also rotatively carried on the stud 38 and xedly connected with the worm-gear 37 is a driving member 39 adapted to drivingly engage the teeth of the corresponding sprocket 20.

The driving member 39 comprises a disc 40 carried by a bushing 42 and a disc 40' carried by a bushing 43, both bushings being rotatively pr'o vided on the shaft 38. ' I'he discs 40 and 40 are xedly interconnected by a plurality of rollers 4l shaped to engage the teeth of the sprocket 20. The driving member 39 is xedly connected with the worm-gear 37 by means of a retaining washer and a screw 45. Thus the worm-gear 37 and the driving member 39 rotate in unison and act as intermediate driving means between the motor `work 36 and the sprocket 20.

It should be well understood that other suitable driving means could be used to drive the sprockets.

The sides 10-10 carry inwardly facing complementary U-shaped channels 50-50 forming loops surrounding' the chains 21-21 and acting as guiding runways or tracks for the display carriers as will be later explained.

Each track 50 comprises two straight portions 51 and 51 provided at the front and at the rear ofthe sides 10-10 along and outside of the chains 21-21, these straight portions extending substantially the whole length of the display window 7. It should be noted that, for reasons later to be explained, the front portions 51 and rear' portions 5l of the track are not symmetrically disposed with regard to the chains, but the front track portions 51 are slightly closer to the chains 21-21 than are the rear portions 5l.

rIhe straight portions 51 and 51 of the tracks are interconnected by upper and lower curved track portions 52 and 52', which are substantially circular but which slightly close toward the front. Preferably the curved track portions 52 and 52 are composed of two circular portions 53 and 54,

and 53 and 54 respectively drawn around different centers. Starting from the rear straight track portion 51 the upper portion 53 and lower portion 53 follow for about 135 circles drawn around the centers of the shafts 16 and 17 re- 1 spectively, these portions being thus concentrical with the sprockets 20.

The curved portions 54 and 54 which connect the portions 53 and 53' vwith the straight front track portion 51 extend approximately 45" and ill.

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are drawn around centers 55, which fall out- My display device is suitable for various types of displays, for instance for the display of panels carrying pictures, printed matter, or the like, and these panels may be standard posters of paper or of other transparentI flexible material, land for the sake of simplicity the display memberswill bereferred to hereafter as posters.

I prefer to subject the posters to a suitable treatment to enhance their transparency to light, for instance, colored paper posters may be treated with a suitable oil whereby not only their transparency to light is increased, but also their colors rendered more vivid.

The poster 85 which consists of a transparent panel carrying. a picture, advertising matter or the like, and has the proper dimensions for which the display window is designed, is provided at its lower end, as shown in Fig. 9, with a reinforcing member in the form of a crimped'metal strip 89. At its upper end, as shown in Fig. 8, the poster is provided with a metal shield 86, crimped at 88 around the end of the poster and forming therewith a hooked portion 87. V

. The poster is detachably secured to a carrier member, which will hereafter be described, and which together with the poster form the display unit.

The carrier comprises a bar-shaped member 60 (see Figs..5 to 7) provided at its rear side with a stiiening angle bar 61. At both of its ends the bar 60 is provided with rectangular openings l72---' 72, which serve, as will be later'I explained, for

the engagement of the pick-up and retarding links 23, which during their travell before the dislplay window engage by means of their pawls 24,

the upper edges 73 of the openings72.

On its four corners the carrier 60 is lprovided with cylindrical guides 62, bymeans of which the carrier is guided in the tracks 50. The guide cylinders are preferably made of fibre or are provided with a bre sleeve. i

The bar member 60 carries rearwardly extend- I ing triangularly-.shaped brackets 63 and 64 respectively. At the top portions the brackets 63 and` 64 are provided with holes 69 forming bearings for the pivots 7l of an idler-roll 70, whereas at their lowerrear end the brackets 63 and 64 are provided/with a bearing 68 and a slot 65 respectively to receive the pivot'97, and the extension 96 of a roller (Fig. 10). The extension 96 is rectangular and the bearing 65 of the left--side bracket 63 has a corresponding shape (see Fig. 7).

IA leaf spring 66 having a rectangular opening 67 corresponding in shape to the extension 96 retains the same in place.

The roller 95 as shown in Figs. 10 and 15, consists of a hollow cylinder 100, and is provided with `endpieees lOl- 101, properly. secured' thereto.

A plug is v fixedly disposed within the cylinder at a suitable distance from its left end.

A rod 103 'provided at one endwith the rectangular projection 96 and on its other end with a stud 108 is rotatively supported in the left end piece 101 and in a bearing 107 of the plug 105 respectively.

Surrounding the rod 103 is a coil-spring 102 anchored with its ends 106 to the plug 105 and with its other end 104 to the rod 103. f

IThe roller 95 is provided with a transversal recess 98 adapted toreeeive the reinforced end 89 of the posters'ii.

To assemble the display unit the roller 95 is inserted with its pivot 97u in the opening 68 of bracket 64 and with its projection 96 in the slot 66 of bracket 63, and is so retained by the slotted leaf-spring' es. 1t shou1d be weu understood that if desired the roller may be permanently secured to the brackets 63 and 64- as the insertion and removalV of the posters takes place without the' removal of the roller 95 from'the brackets.

The roller 95 is given'` the desired tension by winding up its spring 102 through rotation of the roller to a predetermined extent; it will be apparent that while the cylinder 100 rotates withits pivot 97, the projection 96 is. xedly held in the slot 66 of the bracket 63 and the spring 102 is thus given the desired tension, which is also imparted to the roller 95.

With the roller 95 held under the proper ten- `son` and in a position in which the recess 98 is cylinders 62 are forced through the openings 56 of the tracks 50, passed by the springs 57. Upon the insertion of both pairs of its guide cylinders 62 the unit is guided in the tracks 50. A

'I'he individual units are interconnected by engaging with the free hooked end 87 of each poster 85 the upper edge of the carrier bar 60, of the adjoining unit. If, as is the case in the device shown, the poster is secured to its roller 95 by means 'of its lower end, its free upper end is hooked to the carrier bar of -the next unit in advance, (see Figs. 5 and 6). However, if the upper end of the poster is secured to its roller, the free lower end of the poster will be hooked to the carrier next in the rear. 'I hereby on a poster, in any. position of its unit,- two forces are exerted, first the .pull exerted on its one end (in the present case the lower end) by its tensioned roller 95,

vthis pull tending to wind up the poster on its roller; secondly, the pull exerted on the other end tolwhich the poster is unwound in the different positions of the unit during its travel along the tracks thus depends in this case on the distance between its carrier and the carrier next in advance and this distance in its turn is determined by the interlocked operation of various parts of the mechanism and will be more fully explained in connection with the description of the operation oi. the display device.

Pivotally mounted on the two lower front rods 12 are catches 81 biased by springs 83 and carrying cams 82, and pivotally mounted on the upper front rods 11 are catches 77 carried by 1evers75 and biased by springs 78. The function of the in the operation of the device.

To insure that the posters as they appear before the display window `be free from folds and wrinkles, I provide a plurality of slanted straightening levers 90 pivoted at 91, and disposed at the two sides of the display window, which'rest with slight pressure on the poster appearing before the p window, and keep it taut. Proper stops 92 are provided to limit the movement of the levers 90.

The operation of my display device will now be described:

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i. nemesi The individual display unitsare inserted in the device, as has been previously explained, by passing their cylindrical guids 62 through the springcovered openings 56--56. So Ainserted the unit is guided in the tracks -50 by means of its four guide cylinders 62-62. To tie together the successive display units, the-projecting hooked end 87 of each poster 85 is attached to the top edge of the bar member of the unit next in advance, as has been explained in connection with Figs. 5 and 6.

Thus in Fig. 3, which, represents the left side of the display-device, and in which the advance o the chain is shown to be in clockwise direction,.

so that the display units advance upwardly through the display space, the free end of the poster of the unit A-2 is hooked around the bar 60 of the unit A-l; the free end of the poster of unit ifi-3 is hooked around the bar 60 of the unit A-Z, etc.

After the display units have been so tied together, the motors are started which causes the sprockets 20-'20 to drive the chains 21-21 at a constant speed. |lhe chains carry with them the twin pick-up links 23-23 and one or two pairs of retarding links 25.

As has been stated before, the straight front portions 51 of the tracks and the upper and lower curved portions 5-54, which are excentrical with respect to the sprockets 20-20, are closer to the chains than are the straight rear portions 5l and the curved portions 53-53 which are concentric with the sprockets. The pawls 24; of the pick-up links 23 are of such length that they may engage the apertures 72 of a carrier-bar 60 when such apertures are encountered by the pawls 2li in their travel on the excentrically located portions 54 and 54 and the straight front portion 5l.

of the tracks, but not when the pawls 24 travel along rear front portion 51', and the curved track portions 53 and 53.

When the pick-up links 23 in their travel along the lower track portions eireach the cams 82 their pawls 24 force the cams 82 out of their way and thereby free from the catches 8l-8l the carrier bar 60 of a display unit which then assumes the position shown in Fig. 3 to be occupied by the display unit .Ll-3. The pawls 2i at the same time engage the openings 72 of the bar 60 of this unit and this bar is now carried upwardly by the pickup links 23. The carrier 60 of this unit passes before the display window and after that passes the catches 77.

When the links 23-23 assume the position indicated in Fig. 3 their pawls 24 disengage the apertures 72 of the carrier 60 of a unit which then occupies the position shown in the drawings to be occupied by the unit A-2. The carrier bar 60 of this unit is prevented by the catches 77 from dropping back, which engage the lower edge of its bar 60. The pick-up links 23 now proceed with the chains without their pawls further enf gaging any of the carrier bars until the links again ascend in the lower front curved portion of the tracks and after pushing aside the cams 82, as before described, engage the bar 60 of the following display unit, which in the meantime has assumed the position indicated in Fig. 3 as being occupied by the unit A-3.

In Fig. 3 the display device is shown at-a moment at which the pawls 2li- 2li of the pick-up links 23-23 are just about to disengage the carrier of the display unit A-2 after having carried same past the display window 7. The unit A2 is retained in this position through the engagement of the lewe:4 edge of its bar 60 by the catches 77-77 and remains in this position for almost a full revolution of the pick-up links.

In this position of the display unit .Pi-2, the poster of the succeeding display unit A-3, which by meansof its hooked end 87 engages the locked carrier of the display member ifi-2, and of which the carrier 60 is locked by the catches 81, appears fully unrolled in iront of the display Window.

The poster 85 of the unit .fn-3 remains thus displayed in its stretched condition, until the pickup links 23-23 have again reached the position in which their pawls 24T-24 rst cause the catches l81--81 to release the bar 6G of the display unit A-3, and then engage the apertures 'l2-72 of this carrier.

As the carrier 60 of unit ifi-3 moves upwardly, it causes poster 85 of unit A-fi to gradually disappear by re-rolling around its roller 95, and the poster 85 or" the unit .fi-4 to gradually rise before the display window by unrolling from its roller which with its carrier 60 is now retained by the lower catches 8l-8i.

It should be noted that the carrier of unit A- has assumed the position previously occupied by the unit ifi-3, partly due to the pull exerted on its poster 85 by the advancing carrier of unit A--3, and partly due to the pressures exerted by the weight of the succeeding units f1-f5, 1r-6, etc. piled up in the lower portion of the tracks.

As the carrier of the display unit A-3 thus advances and the poster 85 of the unit A-fi gradually unrolls before the display window taking the place gradually given up by the poster 85 of unit A-3, it appears to the onlooker as if the poster 35 of the unit A-S would stand still and the poster 85 of unit l-e would gradually rise in the front of it.

As the carrier of unit [fr-3 passes with its upper guide cylinders 62-62 the catches 77 it abuts against the guide cylinders 62-62 of the preceding unit [i2 and being still in engagement with the pawls 24; of the pick-up links 23-23, it pushes the carrier of A-Z forward along the track and this in turn pushes the carrier of the preceding unit The unit A-l thereby comes to fall with its center of gravity on the descending portion of the track, being however checked in its fall by its engagement with the tongues 26 of the retarding links 25, which are carried by the chains 2l-2l in proper spacing relative to the pick-up rings 23-23.

If desired more than one pair of retarding links may be provided, although as a rule a single pair suffices.

As has already been previously stated, the retarding links 25 are so constructed that in the ascending portion of the tracks their tongues 26 are free to retract when passing the carriers 60 and thus kdo not engage or otherwise interfere with same.

The display units pile up .in the lower curved portion of the track and depending on their number also partly or fully ll up the straight rear track 5i.

The number of display units provided in the device can vary Within comparatively wide limits. For instance, in the display device shown in the drawings twenty units can be provided. In the case of the device being provided with a maximum number of display units the whole track loop is iilled with units, except for that portion of the track which opposes the display window and for lic one lnterspace corresponding to a carrier unit. On the other hand, as has been stated, it is not necessary to fill up the display device to its maximum capacity, and in the device illustrated .satisfactoryoperation is obtained even if the number of units is reduced to six. This feature is of great practical importance as the number of posters to be displayed may be conveniently reduced or increased without affecting in general the operation'of the device.

While I have described a specific embodiment of my invention, it should be well understood that various modifications may suggest themselves without departing from the spirit of the invention, and that more or less of th'e novel features of my invention may be combined fin the display device.

I do not'wish, therefore, to be limited to the specific example shown, but desire the appended claims to be construed as broadly as permissible in View of the prior art.

What I now claim as new and desire by Letters Patent is:

1. A display unit comprising a roller, a carrier for said roller, a spring to bias said roller, said spring being anchored with one end to said roller and with its other end to said carrier, and a to secure poster detachably secured with one end toA said roller and having its free end passing between the carrier and the rller and means to project said free end of the poster beyond said carrier `and said roller.

' plementary guide tracks provided on the two sides of the casing, a plurality of display units, each unit comprising a carrier andguides by means of` which the units are guided in said tracks, and

a poster, said poster at one end being springbiased tov itscarrier and at its other end being attached to one of the adjoining units, and means cooperating with said carriers to successively move said units along said track.

4. A display device comprising a plurality of display units each comprising a bar member, and an endless chainadapted to travel at constant speed, a member on said chain adapted in certain positions of the chain to engage the bar member of a selected unit and to pass the bar members of the units in other positions of the chain without engaging same and a second member on said chain adapted in certain positions of the chain to engage the bar member of another selected unit and to pass the 'bar members of the units in other positions of the chain without engaging same.

5. A display unit comprising a display opening, a looped track'and a looped chain disposed within said track and closely'encircled by same, a plurality of display units guided in said track,

i the distancebetween said track'and said chain being smaller in the region of the display opengage said display units to lift them through said display space and to disengage said units alter they have passed said space, and another member carried by said chain to cause retarded falling down of the display units after they have passed the display space.

7. A display device comprising a housing having a display opening at the front and closed looped tracks on its two sides, looped chains disposed inside of said tracks adjacent to the two sides of the housing and closely spaced to said tracks, driving meansincluding a motor to rotate said chains at a constant speed, said means being encircled by the said tracks and said chains, interlocked display members guided in said tracks, means comprising locking members and pawled links carried by said chains to successively move said members alongthe track and to cause their arrested display before the opening.

8. A display device comprising a housing, a display space and a plurality of display units, each comprising a carrier bar, a roller secured to said carrier bar and being spring-biased thereto, a poster detachably secured with one of its ends to said roller and adapted to Wind around same, said poster having its free end detachably secured to the carrier bar of one of the two adjoining units, said interconnected units thereby forming 'a closed elastic band in which part of the display units are fully wound around their roller, and means to cause the unrolling from its roller of a poster when it passes the display space.

9. In a display device, a housing having a displa'y space, a closed looped track, a looped carrier chain disposed substantially in parallel to said track and means to drive said chain, a pick-up member on saidchain, a plurality of detachable display units, each unit comprising a carrier and guides to guide it in said track, a spring-biased roller mounted on said carrier and a poster secured with one of its ends to said roller and adapted to'wind around the same, the poster having its free end detachably connected to the carrier of one of the adjoining units, said pickup member adapted to engage successive units and lift them through the display space and to disengage said units after they have passed the display space.

10. In a display device a housing comprising a display window provided in the front of said housing, driving means disposed in said housing, two

sidewise disposed looped chains and looped tracks surrounding said chains, a plurality of display units guided in said tracks, a pair of opposite members, one on each chain, ,and adapted to move with said chains to' engage a unit when it approaches said window and to disengage said unit after it has passed said window, and a second pair of opposite members, oneon each chain, and adapted to engage a unit when it enters the rear portion of said housing and to disengage saidunit when it leaves said rear portion.

. 11. A`display `device having a housing, a display Window and a closed looped track, said track consisting of straight front and straight rear portions and upper and lower curved portions, and a plurality of individual spring-biased display units interconnected with each other to form an elastic band, said units adapted to individually pass before said display window in the front straight portion of the track, the other portions of the track being at least partly occupied by display units, and means to cause the intermittent advance of the display units and their successive passage and arrest before the display window.

l2. in a display device, a looped track, a pin rality of removable display units, each ccmpris= ing as a unitary structure, acarrier, guides, a spring-biased roller, and aposter secured with one of its ends to saidspring-biased roller and tending to wind around said roller, said display units being adapted to be moved along said track and being guided therein by their guides, a display window in the front of said device, said display units being interlocked with each otner by interconnecting the iree end of each poster with the carrier of the adjacent unit, said posters assuming in different portions of the track a condition which. varies from being fully wound around its roller, tc being fully unrolled depending on the distance between the carriers to which its two ends are secured, the posters forming an elastic endless band and being adapted to successively unroll before said display window, and means cooperating with said display units to positively engage one or the carriers and thereby cause intermittent advance of the band.

i3. In a display device comprising a casing and a display window on the front of said casing, a driving mechanism disposed at the two sides of the casing and sidewise with regard to said window, eacn of said mechanism comprising a motor, a chain and gear members connecting said motor with said chain, and a shaft interlocking Q the two mechanisms.

la. A dispiay unit comprising a casing having :cercasi a window, a plurality of display units within said casing, each comprising a carrier, an ende1 less traclr to guide said carrier and an endless chain closely encircled bysaid track, and two lug members carried by said chain, one of said lug members having a xecl pawl to engage said carriers for the upward movement of the units past the Window, and the second of said lug members having a retractable pawl and adapted to said carriers for the retarded lowering of the units in the rear portion of the casing.

l5. A display unit comprising a carrier includ= ing a bar member, guide cylinders at the twc ends or' said member, brackets secured to said member close to the two ends thereof, roller pivoted in said brackets, a poster secured to said roller, and a spring which biases said roller and causes the poster to wind up around said roller.

16. In a display device comprising a housing and closed looped tracks secured to the two sides of the housing, a plurality of display units re-= movably disposed in said housing, each comprising a carrier and guide members at the two ends 0f said carrier to guide said carrier in said tracks, a spring-biased roller secured to said carrier and a poster connected with one end to lsaid spring-- biased roller and having at its free end a hocksnaped bm te secure said poster to the carrier of the radjoining unit. t

FRANK J. SPRAGUE.

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