US2113323A - Electrically controlled changeable exhibitor - Google Patents

Description

April 5, 1938.

J. HUTCHlNSON ELECTRICALLY CONTROLLED CHANGEABLE EXHIBITOR Original Filed Dec. l5, 1932 6 Sheets-Sheet 1 INVENTOR. JWZ 57 m,

ATTORNEYS.

April 5, 1938.

u VII'IIIIIIIIIIIIIIIIIII J. HUTCHINSON ELECTRICALLY CONTROLLED CHANGEABLE EXHIBITOR Original Filed Dec. 15, 1932 6 Sheets-Shed? INVENTOR.

' A TTORNEYS.

April 5, 1938. J. HUTCHINSON 2,113,323

ELECTRICALLY CONTROLLED CHANGEABLE EXHIBITOR Original Filed Dec. '15, 1932 6 Sheets-Sheet 4 A TTORNEYS.

April 5, 1938. J. HuTcHmsoN 2,113,323

ELECTRICALLY CONTROLLED CHANGEABLE EXHIBITOR Original Filed Dec. 15, 1932 6 Sheets-Sheet 5 VWXYZ+I&123

9/ v "91 Pl w a 4 m INVENTOR.

A TTORNEYS.

A ril 5, 1938. J. HUTCHlNSON 2,113,323

ELECTRICALLY CONTROLLED CHANGEABLE EXHIBITOR Original Filed Dec. 15, 1932 6 Sheets-Sheet 6 INVENTOR. mffimml, @5411, BY

A TTORNEYS.

Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE ELECTRICALLY CONTROLLED CHANGE- ABLE EXHIBITOR Job Hutchinson, Great Neck, N. Y.

6 Claims.

This invention relates to electrically operated changeable exhibitors for announcing information, and more particularly to display units of the general type disclosed in my prior co-pending application Serial No. 590,484, filed February 2, 1932.

While in said prior application, I have shown and described a device in which the movable display element, carrying a series of characters, is driven at a uniform rate by a rotary motor, in the present case I provide mechanism by which the display element is driven by such a motor intermittently or step-by-step, a distance of one character at a time.

Also, while in said prior application, there is required a number of control wires equal to the number of characters to be displayed, I am enabled, by the present invention, to completely control a unit so as to cause it to display any desired number of characters, by means of a single circuit only.

Among the other and more specific objects of the invention are to provide improved means for accurately positioning and locking the display element after each movement; to prevent, so far as possible, sparking at the various contacts; to devise an improved selector device for automati cally stopping the display element when the desired selected character is reached; and to provide an improved remote control device by means of which the selector is operated.

In order that the invention may be readily understood, reference is had to the accompanying drawings, forming part of this specification, and in which:

Fig. 1 is a side elevation of my improved display unit, parts being shown in section;

Fig. 2 is a plan view thereof with the top plate omitted so as to more clearly show the gearing;

Fig. 3 is a horizontal section taken on a plane just below the gearing shown in Fig. 2;

Fig. 4 is a side elevation of the selector mechanism shown at the center of Fig. 1, the magnets and supporting plate being removed and some of the gearing omitted to more clearly illustrate the construction;

Fig. 5 is a transverse section on a plane at right angles to Fig. 4, also illustrating the selector mechanism, the magnets being omitted, and parts being shown in elevation;

Fig. 6 is a front end elevation of the display unit;

Fig. 7 is a transverse section taken substantially on the line 11 of Fig. 1, looking in the direction of the arrows;

Fig. 8 is an elementary diagram of the circuits necessary to operate one of the improved units;

Figs. 9, l and 11 are views of a remote control device employed tooperate my improved display unit, Fig. 9 being ahorizontal section substanin the direction of the arrows; and Fig. 14 being a front elevation; and

Fig. 15 is a diagram illustrating the wiring necessary for the operation of a group of four of the improved display units.

Referring to the drawings in detail, my improved display unit comprises a top plate I and 'a bottom plate ,2, secured together in suitable spaced relation by spacing rods 3. At the rear end of the unit is a back plate 4 and at the forward end is a front plate 5, the latter having a display opening 6 therein behind which may be placed a transparent screen 1 of glass or the like. It will be noted that this glass is removable and interchangeable, being slid into position from the side and held in place by means of a spring l as shown in Fig. 3. I

Supported between the top and bottom plates are a pair of reels 8 and 9, to the upper ends of the shafts of which are secured gears l0 and H, the latter being angularly adjustable relative to its reel, as indicated in Fig. 2. The gears 10 and H mesh with an idler pinion I2, located between them, so that the reels are geared together. One of the reels, such as 9, is rigidly secured to its shaft, while the other reel 8 is connected with its shaft through a spiral or other spring M.

A web or band l has its ends secured to and is wound upon the reels 8 and 9. Adjacent each side of the display opening 6, and just behind the same, are a pair of guide rollers l6, and the web or band 15 passes around said guide rollers behind said opening as it travels from one reel to the other. The web orband I5 carries a series of individual characters of such size and spacing that they are visible one at a time through the display opening 6. Each of these characters substantially fills the display opening, as is illustrated by the character 4 in Fig. 6.

The web I5 is preferably substantially opaque, while the characters are translucent. A suitable electric lamp I1 is placed behind the portion of the web which extends between the guide rollers l6, and back of the lamp I1 is a suitable reflecter 18. In this way, the characters appearing at the display opening are strongly illuminated. The construction and arrangement of parts so far described is substantially the same as that disclosed in my prior copending application, above identified.

Supported by the top plate I and carried in parallel spaced relation thereto by means of bolts 2|! is an auxiliary plate l9 between which and the top plate the gearing hereinafter described is journalled.

Meshing with the gear H is a gear 2|, secured beneath which and rigid therewith is one member 22 of a Geneva gear. Cooperating with the member 22 is a pin 23, and the complementary member 25 of the Geneva gear, such pin and member being rigidly carried by a gear 24, journalled upon a shaft 46 The gear 24 meshes with a pinion 26 rigid with a gear 21, which in turn meshes with a pinion 28 rigid with a gear 29. This meshes with a pinion 3|], secured to a friction wheel 3|, constituting the end of the chain of gearing by which the reels 8 and 9 are driven.

Adapted to engage the friction wheel 3| is a friction pulley 32, carried by the shaft of a vertically disposed electric motor 33, pivotally mounted at 34 on a bracket carried by the bottom plate 2 of the unit. The pulley 32 is normally held out of engagement with the friction wheel 3| by means of a spring 35 carried by the plate IS. The pulley is adapted to be yieldingly forced into engagement with the friction wheel 3| by means of a leaf spring 36, which bears against the motor on the side thereof opposite to the spring 35. This leaf spring is carried by an armature 31 pivoted at 38 to a fixed bracket and arranged to be attracted by an electromagnet 39.

The armature 31 carries at its free end a pin 40 adapted to engage the cam surface 4| of a spring finger carrying a contact 42 and to force such contact into engagement with a contact 43, carried by a similar spring finger. These contacts are carried by brackets supported on the rear plate 4. One of the contacts, such as 43, is connected with one of a series of five jacks 44, as clearly shown in Fig. 7, these jacks being adapted to receive plugs to complete the control and power circuits when the units are assembled on a display board, as in my prior copending application, above referred to. The other contact 42 is not shown as connected to one of the jacks, because this contact is wired only to elements of the unit itself, as will be seen from an inspection of Fig. 8.

In another prior copending application, Serial No. 595,402, filed February 26, 1932, now Patent No. 2,010,263, I have shown and described an electrically operated changeable exhibitor controlled from a distant station by means of a selector or governing device of the step-by-step type. I propose to employ a step-by-step selector of this general type, but of somewhat improved construction, in connection with the present invention.

Referring particularly to Figs. 1, 3, 4 and 5, it will be seen that to the lower end of the shaft carrying the gear 2| and supported in a bracket Ill is secured a pinion 45. This meshes with a large gear 46, journalled freely on the lower end of the stud or shaft 46 This gear 46 meshes in turn with a crown gear 41, mounted to rotate about a fixed shaft 48, supported between spaced vertical plates 49 and 5D. Rigidly secured to the crown gear 4'! is a disc of insulating material which constitutes the hub that bears upon the shaft 48, and which is formed with a laterally projecting annular rib 5|. On the outside of this rib is a metallic rim or band 52, and extending radially inward from this rim or band and terminating flush with the inner surface of the annular rib 5| is a narrow metallic contact segment 53, as clearly shown in Fig. 4. Bearing upon the metallic rim 52 is a brush 54, by means of which an electrical connection with the rim is established.

Also mounted to rotate on the shaft 48 is a toothed disk 58 of insulating material, to which is secured a ratchet Wheel 55. A spring pawl 56 bears against the teeth of this ratchet wheel and serves both as a locking pawl to prevent reverse rotation thereof, and also as a brush to establish electrical connection therewith. Secured to and moving with the ratchet wheel 55 is another brush or spring finger 51, which bears against and rides upon the inner surface of the annular rib 5|. When this contact brush or spring finger engages the contact segment 53, it will be seen that an electrical connection is established from the brush 5'! (and thus from the brush 56 through the ratchet wheel 55 to the band 52 and thence to the brush 54). At all other times, the electrical connection between these parts is broken, and the circuit in which they are included is open.

Carried on the outside of the crown gear 41 is a stud or pin 59, which is adapted to engage and shift the lever 60 of a reversing switch 60.

It will be understood that the gearing ratio between the reel 9 and the crown gear 41 is such that this crown gear makes one complete revolution as the web or band l5 travels from one end to the other of its limits of movement. Consequently, the entire series of characters carried by said web pass by the display opening as the crown gear 41 makes one revolution. Thus, as each end of the series of characters is reached and the web approaches its limit of movement in either direction, the reversing switch 60 is operated by the stud 59 and the motor reversed so as to drive the web in the opposite direction. This motor reversing feature is substantially the same as that disclosed and claimed in the first of my above mentioned prior copending applications, and therefore needs no further detailed description here.

Mounted on a bracket 62 on the side of plate 49 opposite to that on which the ratchet wheel 55 is located is an electro-magnet or relay 6|, having an armature 63 pivoted at 64 to the plate 49 and normally held in retracted position by means of a spring 65. The free end of the armature carries a switch plate 66 which, when the magnet is energized, is adapted to engage and bridge a pair of fixed contacts 61 and 68, (see Figs. 1 and 5).

Rigid with the armature 63 is a double ended driving pawl or pallet having arms 69 and 18 (see Fig. 4), which pawl or pallet is adapted to engage the V-shaped teeth of the disc 58 and cause such disc to rotate as the armature 63 is oscillated. Each oscillation of the armature moves the disc 58 a distance of one tooth, so that the elements just described constitute step-bystep mechanism for shifting the disc 58, which constitutes one member of the selector.

Referring now to Fig. 8, H and 12 represent a pair of spring contacts constituting part of the remote control device and located at a distant station, as hereinafter more fully described. The contact 12 is connected by wire 13 with one side of the relay magnet 6|, while the contact H is connected to one side of the line and the other side of the relay 6| is connected through wire 14 with the other side of the line or source of supply. A wire 15 connects contact 61 with a wire 19, connecting contact 42 with one side of the magnet 39, while the other side of the magnet 39 is connected by wire 76 to the reversing switch 69 and through it by one of the two wires 1'! with the motor 33. The other side of the motor is connected as by wire 78 with one side of the supply circuit, while the contact 43 is connected with the other side of the supply circuit. The brush 54 of the selector is connected with the wire 76, and the other brush 5'! of the selector is connected with the contact 61. A switch 80 is provided for controlling the lamp I! by means ofawire 8|.

Assuming the contacts H, 72 at the control station to be momentarily closed, a circuit is established from one side of the supply line through these contacts, through wire 13, and relays 6| to the other side of the supply line. This energizes relay 5 I, and causes it to bring the switch plate 66 into engagement with the contacts 61 and 68. This closes a circuit from the positive side of the line through wire 14, contacts 68 and 61, wire 15, wire 19, magnet 39, wire 16, reversing switch 60, wire TI, to and through the motor 33 and thence through wire 18 to the negative side of the line. This immediately energizes the magnet 39 and causes it to attract its armature. As the armature comes down, it engages the cam surface 4| and forces the contacts 42 and 43 together. A new circuit is thereupon established from the positive side of the line through the contacts 43, 42, wire 19 and magnet 39, as before, this circuit, however, being independent of the relay contacts 61 and 68. As this new circuit passes through magnet 39, the energization of this magnet is continued, with the'result that it becomes a holding magnet and maintains its own circuit closed at the contacts 42, 43. The motor then begins to run and continues to run so long as the contacts 42, 43 remain closed.

The movement of the armature 31 toward the magnet 39 also has another effect, namely, it increases the tension on the spring 36 (see Fig. 1) and causes it to rock the motor on its pivot 34 and yieldingly forces the friction pinion 32 into engagement with the friction wheel 3| Thus, as the motor begins to run, an operative driving connection is established between it and the train of gears which drive the reels and also the selector.

It may be noted at this point that the movement of the armature 63 of the relay 6| also produces another effect, in addition to closing the circuit between the contacts 61 and 68, namely, it oscillates the driving pawl or pallet 69, 18, and moves the toothed disc 58 around one notch, thus shifting the contact brush 5! (see Fig. 4) around through a similar angle.

Referring again to Fig. 8, the motor, having been started as above described, continues to run until the contact segment 53 and contact brush 51 are brought into engagement. At the moment of such engagement, a connection is established from wire 19 through wire 15 up through brush 5?, and thence through contact segment 53, brush 54, and reversing switch and motor to the negative side of the line, thus short circuiting magnet 39 and causing it to be deenergized. This magnet therefore immediately releases its armature, which, under the influence of spring 36, rises and permits contacts 42 and 43 to open, thus interrupting the motor circuit. Therefore, tension on the spring 36 being relieved, the spring 35 predominates and moves the pinion 32 away from the friction wheel 3|.

Thus, the circuit to the motor is opened and the motor is simultaneously disconnected from the train of gearing.

It will be noted that the contacts 42 and 43 are the only contacts in the unit which are opened while carrying current. It will be noted that instead of opening the circuit of magnet 39, with consequent sparking, I de-energize this magnet by short-circuiting it, as above described. Also, by the time the relay BI is tie-energized and the switch plate 66 leaves the contacts '6! and 68, these contacts are no longer carrying current, as the circuit has been closed at contacts 42, 43. Thus, there is no sparking at the contacts 61 and 68. Similarly, no circuit is broken at the selector while carrying current, the circuit being closed through the segment 53, but not opened again until the circuit is dead. Thus, it will be seen that I have provided a system of electrical connections and controls which reduce to a minimum the sparking at contacts, and thus greatly lengthen the life of the contact devices.

In connection with the contacts H and 12, above described, I preferably employ the improved remote control device illustrated in detail in Figs. 9 to 14. By reference to these figures, it will be seen that the remote control device is constructed in the form of a relatively long and narrow unit so that a plurality of these devices may be assembled in bank formation side by side to constitute a control board. Each unit comprises a top plate 86, a bottom plate 81, a rear plate 88, and a front plate 89. Like the display unit, this control unit has a sight opening 98 in its front plate 89, and the contacts 1| and 12 are connected by wires 13 and I3 to jacks l3 set in the rear plate 88. These jacks are adapted to receive plugs to which the wiring on the back of the control board is connected. Thus, it will be understood, the control wires extend from the plugs on the control board to the plugs on the display board, and the'control and display units are detachably connected with these wires by means of the jacks.

Extending from the front plate to the rear plate and dividing the control unit into upper and lower compartments is a shelf or partition wall 9|, on the lower side of which the contacts H and 12 are supported.

Pivotally mounted, as at 84 on the bottom plate of the control unit, is a lever or actuatingdevice 83, extending forwardly through a slot in the front wall 89 of the unit and terminating outside of such wall in a button or'thumb piece 85. The rear end of this lever is adapted to engage under the contact II as the lever isdepressed, and force it upwardly into engagement'with the contact 12, as illustrated in dotted lines in Fig. 11.

Mounted in the upper compartment of the control unit between the plates 86 and 9| are two polygonal pulleys 92 and 93, disposed respectively adjacent the front and adjacent the rear end of the unit, and mounted upon vertical shafts 92 and 93. An endless chain composed of a series of blocks hinged together like the links of a sprocket chain, passes around the two pulleys 92 and 93, and substantially fills the space between the plates 86 and 9|. Each of these blocks bears a character, the series of characters making up the chain corresponding exactly both in kind, numberand position with the characters appearing on the web l5 of the display unit.

Secured to the lower end of the shaft 92 beneath the plate 9| is a ratchet wheel 95 and adapted to engage this ratchet wheel is a spring 1 pressed pawl 96 carried at the free end ofa lever 9'! pivotally mounted at 98 on the plate 9|. An arm 83 rigid with the lever 83, projects up and into a socket in the lever 9'1, so that as the lever 83 is rocked upon its pivot 84, the lever 91 is also oscillated and the ratchet wheel 95 turned stepby-step. It will be noted that the number of teeth on the ratchet wheel 25 correspond with the number of faces on the polygonal pulley 92, so that this pulley is shifted a distance equal to the width of one face, for each actuation of the lever 91. It will, of course, be understood that the faces of the pulley 92 are of such width that each will just accommodate one of the blocks forming the chain 94. Furthermore, these blocks are of such size as to be displayed one at a time at the sight opening 99, as the chain passes around the pulley.

To the lower end of the shaft 93 carrying the pulley 93 is secured a notched wheel 99, with which is arranged to cooperate a stop lever I99 pivotally mounted on the plate 9| and having at its end a roller adapted to enter the notches in the wheel 99. A spring Hill urges the lever resiliently toward the wheel.

The number of notches in the wheel 99 corresponds, of course, with the number of faces on the pulley 93, so that as the chain is driven stepby-step, by means of the ratchet 95, as described, the roller on the end of lever I snaps successively into the notches of the wheel 99, as each block passes around the pulley and serves to cause the chain to be shifted accurately a distance equal to the width of one block at each step. In other words, the wheel 99 and associated parts serve to prevent drifting or overrunning of the chain and to accurately center each block in the sight opening 90.

From the foregoing, the operation of my improved apparatus can now be clearly understood. Assuming that the character A appears at the sight opening of the remote control unit, as shown in Fig. 14, the character A on the web l5 of the display unit will also appear at the display opening 6 thereof. Let it be supposed that the operator at the remote control station desires to cause the display unit to display the letter N. He will successively depress the thumb piece or button 85, the number of times necessary to move the chain or indicator element step-by-step until the character N appears at the sight opening 99 thereof, this chain or indicator element being shifted, as above described, a space of one character for each stroke of the lever 83. At each stroke also, the contacts ll, 12, are momentarily closed, the lever 83 being returned to normal position by a spring 93', (see Fig. 11). Each closure of the contacts H, 12 causes a momentary energization of the relay 6|, as above described, and a shifting of the toothed disc 58 of the selector an angular distance equal to the width of one tooth. The number of teeth on this disc bears a definite relation to the number of characters on the display and indicator elements, and as shown, the number of teeth is equal to the number of characters. Thus, in passing from A to N, the disc 58 would be advanced a distance of thirteen teeth, this advance being in a clockwise direction, as viewed in Fig. 4. It is also assumed, as would necessarily be the case, that, at the end of the previous shifting operation, or, at the beginning of the operation being described, the contact segment 53 would be in engagement with the brush 5!. Thus, in the example just given, the brush 51, moving with the ratchet wheel 55 and toothed disc 58, would be advanced a distance of thirteen teeth ahead of the position occupied by the contact segment 53.

As previously described, the first energization of the relay 6| results in putting the motor in operation and it will be observed that the motor continues running during the subsequent energizations of the relay 6|, these subsequent energizations being idle so far as any electrical effect is concerned, the magnet 39 remaining energized and maintaining the motor circuit closed so long as the brush 5'! is shifted fast enough to keep awayfrom segment 53. The subsequent energizetions of the relay 6| serve merely to operate the driving pawl or pallet and advance the ratchet wheel of the selector, as above set forth. Thus, it is immaterial at what rate or speed the lever 83 of the remote control device is operated. It may be oscillated as rapidly as possible, until the desired character appears at the sight opening, and the display unit will follow at whatever speed it may be designed to run, the motor beginning to run upon the first actuation of the lever 83 and continuing during the subsequent actuations thereof.

In Fig. 8, the brush 51 is shown as having been set up or advanced an angular distance from the contact segment 53 corresponding with a dozen or more teeth. As soon as the motor begins to run, the pinion 45, through the gear 46, drives the crown gear 4'! and thus the segment 53, carried by the disc secured to such crown gear, is caused totravel around, until it overtakes and catches up with the brush 51, resting in the position to which it has finally been shifted by the last stroke of the control device and the last energization of the relay 6|. At the moment that contact is established between the segment 53 and the brush 51, the magnet 39 is shortcircuited, the contacts 42, 43 opened, and the motor deprived of current and also disconnected from the train of gearing, as above set forth. Thus, in the example given, if the brush 5'! had been shifted or advanced an angular distance corresponding to thirteen teeth or character spaces, then when the segment 53 engages it, and the mechanism is stopped, the letter N on the web l5 would have reached display position.

If it be desired to display next the letter E for example, the operator actuates the lever 83 a sufficient number of times to move the indicator chain around in the same direction until the letter E appears at the sight opening. In doing this, of course, all of the characters in the series subsequent to the letter N pass by the sight opening and these are followed by the first four letters at the beginning of the series until the letter E is reached. However, in order to shift the web at the display unit so as to cause the letter E to be displayed, the web travels first from the letter N to the end of the series of characters, and is then reversed and travels back to the letter E, where it is automatically stopped, as above described. This operation is practically the same as that described in my prior copending applications, above identified.

By virtue of the presence of the Geneva gear 22, 23, 25 in the train of gearing interposed between the motor and the reels, as shown in Fig. 2, it will be seen that the reels are driven intermittently, and that they are locked after each movement. In the embodiment shown, the Geneva gear turns the gear 2| a quarter of a revolution at each step, and is locked after each step by reason of the engagement of the periphry' of member 25 with the concave sides of the member 22. The ratio between the gear 2| and the gear I I, and the spacing of the characters on the web is such that each step of the Geneva gear shifts the web a distance equal to one character space. Thus, as the motor runs continuously, the reels and web are driven intermittently, one character at a time, and the web momentarily comes to rest after each successive character has been shifted to display position.

In addition to locking the reels after each intermittent movement thereof, as above described, so as to prevent drifting or coasting, the Geneva gear has another and important function. In both of my said prior copending applications, I have illustrated and described what I have termed main and auxiliary governing devices for automatically stopping the web with the selected character accurately registering with the display opening, the main device being described as approximately governing the position of the web, and the auxiliary device being described as serving to accurately position the web, the movement of the web being controlled jointly by the two governing devices. In said prior copending applications, both governing devices are in the nature of electrical circuit closers, both serving to jointly control the motor circuit.

In said prior copending applications, the impossibility of accurately positioning the web by means of a single circuit controlling or selector device is pointed out, this impossibility being due to the fact that the selector is necessarily geared down very low, as compared with the reels, so that a relatively large discrepancy in the position of the web would result from a very small inaccuracy in the movement of the selector. The same is true of the selector mechanism forming part of the present invention. Although, as above described, the motor circuit is opened and the motor disconnected from the train of gearing when the contact segment 53 of the selector engages the brush 57, this would not insure the accurate positioning of the desired character in registry with the display opening. The selector mechanism therefore in this case also constitutes only a main or approximate governing device.

While in said prior copending applications, the auxiliary or accurate governing device is electrical, I have provided in the present invention an auxiliary or accurate position governing device which is mechanical. In other words, in the organization as shown and described in the present case, the Geneva gear itself serves as this auxiliary or accurate governing device.

This is accomplished by so adjusting the Geneva gear relative to the gear II, the gear H relative to the reel 9, and the position of the characters on the web that when the member 22 of the Geneva gear momentarily stops or comes to rest after each step or intermittent movement, acharacter is accurately presented at the display opening 6. Thus, by virtue of this arrangement, the web always stops in a position in which a character accurately registers with the display opening.

By reference to Figs. 1 and 3, it will be noted that the crown gear 41 and associated parts are also driven intermittently through the gear 46 and pinion 45 by the Geneva gear. Consequent- 13', as the contact segment 53 travels aroundand finally engages the brush 51, it must necessarily engage it during a step of the Geneva gear member 22, as after the completion of one step, it remains stationary until the beginning of the next step. Moreover, the speed and inertia of the parts and the ratio of the train of gearing connecting the motor with the Geneva gear are such that, when the contact 53 engages the brush 5'1 and the motor is de-energized and disconnected from the train of gearing, as described, the Geneva gear will always complete the step which it is making before coming to rest, but will not begin another step.

It will be further observed that the active movement of the pin 23, during which it causes a step of the member 22, is only about one-quarter of the revolution of the gear 24, and that about three-quarters of such revolution is idle. This idle three-quarters of a revolution is ample to take care of any running or drifting of the motor or train of gears after the completion of the step which brought the contact 53 into engagement with the brush. Hence, the selector serves to disconnect the motor approximately when the desired character reaches display position and during the step of the Geneva gear that brings such character into position, and the gearing described insures the completion of the step and the bringing of the selected character into accurate registry with the display opening.

From the foregoing, it will be seen that the Geneva gear therefore performs two functions, namely, it insures the accurate positioning of the selected character at the display opening and it simultaneously locks the web after each intermittent movement so as to positively prevent drifting or coasting thereof.

The foregoing discussion, it will be seen, is based upon the assumption that equal angular movements of the Geneva gear and reel 9 produce equal linear displacements of the web at all times. This, however, is not strictly true, because the effective diameter of the reel changes, as the web iswound thereon or unwound therefrom. Thus, if the characters were uniformly spaced upon the web, it will be seen that a different angular movement of the reel would be required to shift from one character to another near the beginning of the series, than would be necessary to shift from one character to the next, near the end of the series, and this would, of course, interfere with the operation of the Geneva gear, as above described, and accurate positioning of the characters at the display opening would be impossible.

In order, however, to compensate for this changing effective diameter of the reel, and to insure that each of the characters throughout the series is accurately centered in the display opening, I progressively vary the spacing of the characters on the web from one end of the series to the other. By this simple expedient, I am enabled to achieve the result that the same angular movement of the reel is required to shift the Web from one character to the next, throughout the entire series of characters. Therefore, with this arrangement, the Geneva gear, operating as described, serves in practice to cause each character to accurately register with the display opening, whatever the position of the character in the series may be. I therefore regard this progressively varying spacing of the characters on the web as an important feature of the invention.

As already mentioned, I contemplate assembling a plurality of my improved display units to build up a display board, andto arrange them in horizontal rows so as to constitute lines of reading matter. In Fig. 15, I have illustrated the circuit connections for four units, thus assembled. In

this view, the various mechanical elements are illustrated conventionally in perspective, and are identified by the same reference characters as those employed in the other views.

From an inspection of this Fig. 15, it will be seen that but a single control circuit comprising the wire designated 13 is required to enable each unit to be controlled from its corresponding remote control station. This wire 13 extends from the remote control contact 12 to the relay Bl, as in Fig. 8. In addition to the control wire 13, there must extend to each unit a pair of power supply wires 14, 18, for operating the motor, and a pair of lighting wires for supplying the lamp I1. These are shown in the drawings, and it will be noted that there are just five wires extending to each unit. As above explained, these wires are run on the back of the display board and connected to plugs with which the five jacks carried by the inner plate of the unit, as shown in Fig. 7, are adapted to engage.

It will be noted that each lighting switch controls the lamps of a plurality of units, which lamps are connected to the wires such as 8| in multiple.

What I claim is:

1. A self-contained changeable exhibitor unit comprising a relatively long, narrow frame having a display opening at its front end, a pair of reels mounted in said frame, one behind the other, a web carried by said reels, means for guiding said web so that it will pass behind said display opening as it travels from one reel to the other, an electric motor mounted adjacent the other end of said frame, a train of gearing extending from said motor to said reels for driving the latter, and a selector for controlling said motor, said selector comprising a pair of co-axial relatively rotatable members, one of said members being operatively connected with said gearing to be driven thereby, and electromagnetic means for actuating the other member, and both members, together with said electromagnetic means, being disposed within said frame at a point between said reels and motor.

2. A self-contained changeable exhibitor unit comprising a relatively long, narrow frame having a display opening at its front end, a pair of reels mounted in said frame, one behind the other, a web carried by said reels, means for guiding said web so that it will pass behind said display opening as it travels from one reel to the other, an electric motor mounted adjacent the other end of said frame, a train of gearing extending from said motor to said reels, for driving the latter, the shafts of the motor and of all of the elements of said gearing being substantially parallel with the axes of said reels, and a selector for controlling said motor, said selector comprising a pair of co-axial relatively rotatable members, one of said members being operatively connected with said gearing to be driven thereby, and electromagnetic means for actuating the other member, and both members, together with said electromagnetic means, being disposed within said frame at a point between said reels and motor, said train of gears overlying said selector.

3. A changeable exhibitor comprising a frame having a display opening, a display element bearing a series of characters visible, one at a time through said opening, a motor for shifting said element, a selector mounted in said frame and comprising a pair of co-axial relatively rotatable members, remote controlled electrically operated means for setting one member of said selector step-by-step to a predetermined position corresponding with that of a desired character on said element, means for automatically putting said motor into operation at the first step of said selector member, means whereby said motor continues to run while further movements of said selector member take place, the other member of said selector being driven by said motor, and means including said selector for automatically arresting the travel of said display element when w the desired character for which said first selector member has been finally set reaches said display opening.

4. A changeable exhibitor comprising a movable display element, a selector device comprising a pair of relatively movable rotatable members, one of said members being operatively connected with said display element, remote controlled electrically operated means for setting the other member of said selector step-by-step to a predetermined position corresponding with that of a desired character on said element, means for causing said display element to begin to move at the first step of said electrically operated selector member, means for causing said display element to continue moving during subsequent steps of said selector member at a definite rate regardless of the rapidity with which said selector member is operated, and automatic means including said selector for eventually arresting said display element at a position corresponding to that to which said electrically operated selector member has finally been set.

5. A changeable exhibitor comprising a movable display element, a rotary motor for moving the same, a selector for controlling said motor, said selector comprising a pair of relatively movable rotatable members, means whereby said motor drives one of said members, electrically actuated step-by-step means for shifting the other of said members, a remote control station, a single circuit connecting said remote control station with said exhibitor, means operating over said circuit for giving to said electrically actuated selector member an initial movement and for simultaneously causing said motor to begin to run, means also operating over said circuit for impartmg additional movements to said selector member to shift it to any desired position while said motor continues to run, and automatic means including said selector for stopping said motor when said display element reaches a position corresponding with that to which the electrically actuated selector member has been shifted.

6. A changeable exhibitor comprising a frame having a display opening, a display web bearing a series of characters visible one at a time through said opening, a rotary motor, a train of gearing including a Geneva gear through which said motor drives said web, whereby, while said motor runs continuously, said web is caused to travel intermittently and to pause momentarily as each character reaches a display position adjacent said opening, a selector device for controlling said motor, means for setting a part of said selector device to any desired predetermined position, and means including said selector for automatically arresting the movement of said web at a point corresponding with that to which said selector part has been set, the said Geneva gear serving, when the web is so arrested, to accurately center the selected character in the display opening.

JOB HUTCHINSON.

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