US2211320A - Photoelectric controlling device - Google Patents

Description

Aug. 13, 1940. G. EFRON PHOTOELECTRIC CONTROLLING DEVICE Filed Jan. 14, 1938 4 Sheets-Sheet l lll/111111.

INVENTOR. GEORGE EF/ioN im m ATTORNEY.

Aug. 13, 1940. G, EFRQN 2,211,320

PHToELEcTRI CONTROLLING DEVICE Filed Jan- 14, 1938 4 Sheets-Sheet 2 INVENTOR.

ATTORNEY.

u8 13, 1940 G. EFRoN 2,211,320

PHDTQELECTRIC CONTROLLING DEVICE Filed Jan. 14. 1938 4 Sheets-Sheet 3 INVENTOR. GEORGE P/PON ATTORNEY.

Aug. 13, 1940. G. EFoN 2,211,320

PHOTDELECTRIC CONTROLLING DEVICE Filed Jan. 14, 1938 4 Sheets-Sheet 4 "wl-m1 333 III ATTORNEY.

Patented Aug. 13, 1940 UNITED STATES PATENT OFFICE 12 Claims.

The present invention relates to a photoelectric controlling device of the type in which characters are explored, and a controller is operated when the identity of an explored character is established by comparison with a negative thereof. A conventional apparatus of this type contains a photoelectric unit adapted to control a switch of an operating circuit when the light impinging on the photosensitive surface of the unit is a minimum. Such minimum occurs when alight beam containing the image of a character and another beam containing a negative image of a character coincide. In order to obtain such coincidence, a set of negatives to be comparedy with the character to be explored is movable relative to a light-source. This type of wellknown device has the drawback that the stationary light beam carrying the negative image constantly changes not only in its intensity but also in its shape, and that owing to the movement of lthe negatives there is practically only an iniinitestimal time of true coincidence frequently insuiiicient for a reaction of the photosensitive unit.

Anobject of the invention is to avoid said drawback and to maintain the coincidence of the image of a comparison character and of a character to be explored for a deiinite length of time.

A further object is to obtain images 4of strong light intensity with the aid of a relatively weak light source.

Another object of the invention is to provide an apparatus of substantially symmetric structure which is simple in its arrangement.

The invention consists in means for creating a. movable light beam in connection with stationary comparison characters and an optical system whereby an image may be produced which is stationary for a definite time.

The invention further consists in stationary compa-rison characters of equal shape but larger size than the corresponding characters to be explored, in combination with means for reducing the size of the images of the comparison characters to that of the characters to be explored.

'I'he invention also comprises means for casting the image of a, comparison character upon a character to be explored while the image of a preceding character still prevails so that the times of the presence o1 the images overlap each other.

The invention consists also in means for casting a light beam through a, stationary comparison character, and for reilecting its image upon the (Cl. 23S-61.11)

character to be explored, and further on upon the sensitive surface of the photosensitive unit.

. movable beam upon such mirrors, and for superimposing the images of said mirrors by the aid of said beam upon a character to be explored.

Further details and objects of the invention may be apparent from the description herein- 10 after, and the appended drawings illustrating embodiments of the invention by way oi example.

In the drawings,

Fig. 1 is a longitudinal section of an embodiment of the invention; 15

Figs. 2 and 3 are sections along lines 2-2 and 3 3 respectively, of Fig. 1;

Fig. 4 is a development of a cylinder carrying the comparison characters;

Figs. 5 and 6 show two different modiiications 20 of a portion of the embodiment oi Fig. 1;

Fig. 7 is a longitudinal section of another embodiment of the invention in its preferred form:

Figs. 8 and 9 are an elevation and a sectional view of a part of the embodiment of Fig. 7;

Figs. 10 and 11 are modifications of Figs. 8 and 9; and

Fig. 12 is a circuit diagram.

Referring now to Figs. 1 tc 4, the apparatus comprising the photoelectric controller is denoted 30 by l. In operative relation thereto, a carrier 2 of suitable design is arranged which is diagrammatically shown like a typewriter cylinder 3 with a sheet of paper 4 having characters 5 thereon. No means have been shown for bringing a par- 35 ticular area oi.' the carrier with a character therein into operative position relative to controller I,

because such means are well-known in the art and do not form part of the present invention. The photoelectric controller comprises a photosensitive unit 6 such as aphotoelectric cell with accessoria] parts available as a unit on the market and described e. g. in the catalogue CR7505 of the General Electric Company on Photo- Electric Relays, and furthermore, a light source 5 1, a set of comparison characters, means for directing light rays from said source 1 so as to impinge on an area of the carrier 2 of the characters to be explored, and switching means 8 for the control of aplurality of circuits. Said carrier 2 is so positioned that said area can reiiect the light rays toward the unit 6. Such reflection from the carrier'will be either regular or irregular, depending on the optical smoothness or roughne of the carrier surface. This difference,

however, is immaterial since the unit 6 does not distinguish in its sensitiveness between direct and scattered light. In the illustrated embodiment, the mentioned parts are housed in a casing having a substantially cylindric portion 9, a co-axial top portion I0 in the shape of a truncated cone, and a partition II. Within the casing, two cenlcral chambers I2 and I3 are provided, in which unit B, andthe light source 1 are respectively mounted. A parabolic reflector I5 and a collector lens I6' are provided so as to guide a light beam downward in the direction of the apparatus axis 20. The set of comparison characters is housed in the casing portion 9, and may be made in various ways, for instance, as shown in Fig. 1. In this iigure, a hollow cylinder I4 is attached to the lower side of partition I I, coaxial withaxis 29, and is provided with at least as many apertures as there are characters to be explored. A lm ring I1 covers the apertures I1. In front of the latter, lm portions I1" (see Fig. 4) in the shapes of the various comparison characters are pervious to light. The remainder of the film is impervious to light. The comparison characters I1" correspond in shape to the characters 5 respectively, but are larger in size than the latterzior reasons to be explained hereinafter. The cylindermI may be removably secured to partition I I for instance, by means of screws I8, so that another cylinder may be appplied if the same apparatus is to be used in connection with a diiereht set of characters.

Means are provided to render the light beam movable so that the 1beam may pass through the comparison characters one after the other, and travel on via the character to be explored towards the photosensitive vunit 6. Such means may consist of an inclined plane mirror I9 rotatable about the axis 20 of the light beam of lamp 1. For this purpose a disc 2I is provided on a shaft 22 of an electric motor 23, the latter being secured to the removable bottom wall 24 of the casing portion 9. -Mirror I9 is mounted on the disc 2| and so inclined that a beam of light emitted by lamp 1 and impinging on the mirror is reflected to rotate together with the mirror and to pass through the apertures I1 and comparison characters I1" one after the other. Between disc 2| and bottom Wall 24 a multiple switch is arranged which comprises a set of stationary contacting elements 25 on a circle about axis 20, and a contact arm 26 secured to shaft 22 so as to rotate in synchronism with mirror I9. The contacting elements 25 and arm 26 are so arranged in relation to the comparison characters I1" and mirror I9, that arm 26 contacts a certain element 25 when the light beam reiiected by mirror I9 passes through a corresponding aperture I1. In other words, each of the comparison .characters is coordinated to one of the stationary elements, and as each of the elements is part of an individual actuating circuit 21 (see Fig. 12) of a set of circuits, the comparison characters are also coordinated to said circuits respectively.

A set of stationary inclined mirrors 28 is mounted on bottom wall' 24 .opposite to the comparison characters I1". There are as many mirrors 28 as there are characters, and their inclination is such that all rays passing through characters I1 are so reected by mirrors 28 as to converge to a denite point on axis 20. The carrier 2 of the characters 5 is so located that said point lies in the center .of the area containing a character which is in the positionfor being light rays, and motor 23 rotates.

explored. In the upper portion I0 of the casing, a set of lenses 29 may be arranged to produce real images of the comparison characters. With regard to the lenses 29 diagrammatically shown in the iigures it is immaterial whether a single lens or a combination of lenses is used for each individual of the set, in other'words whether lenses are selected which produce a real upright or a real inverted image, because the type of the lenses and the shape of the comparison characters can be easily adapted to each other so as to produce images which cover the corresponding characters. This is particularly easy in the case of the lm strip I1 which may be applied either in the manner indicated or turned upside down and inside out whereby upright characters will be inverted. The lenses 29 are so located in relation to mirrors 28 as to reduce-the cross-sections of the beams reiiected by mirrors 28 to the size of the characters 5. Such reduction is unnecessary if the characters I1" of cylinder I4 have the same size as the corresponding characters 5. However, it is advisable to use comparison characters of a size larger than that of the characters to be explored, because in that case a relatively weak lamp 1 is sufficient to produce the necessary light intensity of the reiiected beams. Lenses 29 may be fastened in a mount 30 attached to chamber I2. A collector lenses 32 is mounted in a tubular extension 3| to project the light beam impinging upon and reilected by the area of the pertaining character 5 to the photosensitive unit 6. In order to permit the passage of the reflected beam, apertures of suitable size are provided in the top of the casing at 33 and in the partition I I and 34.

The electric connections of the apparatus are shown in Fig. l2. The photosensitive unit 6, the light source 1 and the motor 23 are connected to an electric source i via a main switch 35. Another electric source 36 is connected to unit 6 by wire 31 and to the contact arm 26 by wire 38 and ring 38. The actuating circuits 21 start at the contact elements 25 and have a common return lead 39 for the current back to the unit 6. The actuating circuits may serve to provide external apparatus with current, so as to cause predetermined functions in such external apparatus under the control of the photosensitive unit and of a character to be explored. Individual means operative by current in the external apparatus are diagrammatically indicated by inductances 48 in Fig. 12.

The described apparatus operates in the following manner: First, the character carrier 2 is so adjusted that the character to be explored is in the operative position, that is to say, that its center lies substantially on axis 20 in the point to which the light rays from the mirrors 28 converge. When switch 35 is in its closed position, the photoelectric unit is excited, lamp 1 emits Driven by motor 23, the mirror I9 and contact arm 26 rotate also, and the beam of light projected by lamp 1 with reflector I5 and lens I6," and reflected by' mirror I9 travels along a circle on the inner wall of cylinder I4. Wherever the beam nds an aperture i. e. a comparison character I1, it passes on to the corresponding mirror 28 and through the coordinate lens 29 and is superimposed on the characters 5 which happens to be in the operative position, for instance, the character 3 in Fig. 1. From there, the beam is reected upon the unit 6 through lens 32. Since the characters 5 are dark on a light background, and the beam passing through the comparison characters furnishes light images, a minimum of light will be reilected upon the photosensitive unit when the beam cross-section corresponds in shape and size to that of the character to be explored. This will be the casein the example otFig. 1 when the light beam passes through the comparison character representing the character I. In the corresponding position of mirror I8, contact arm 28 contacts the coordinate element 25. Owing to the prevailing minimum of light impinging on the unit 6, the latter responds causing the passage oi current which iiows from electric source 36 through wire 38, ring 38', arm 28, corresponding circuit 21, return lead 38, unit 6, and wire 31 back to the source 3B, thereby actuating the external device indicated by inductance 40 in Fig. 12. n

It is a particular feature ot the apparatus according to the invention, that the image of a comparison character projected upon the character to be explored remains stationary as long as any light reflected by mirror I9 passes through the corresponding comparison character during the rotation of the mirror I9. This stationarlness is certainly not to be understood as meaning that the entire character to be explored is covered at once by the entire image oi the corresponding comparison character. But, whenever even only a portion of the image is cast upon the character to be explored, such image portion will always cover the corresponding portion oi' the character. In other words, the position of the image relatively to that of the character remains constant. This phenomenon is due to the fact that in the optical system plane mirrors I9 and 28 are used, and that iilm I1 as well as mirrors 28 remain stationary with respect to the character carrier. While the image thus is stationary, its light intensity increases from zero to a maximum and, then, decreases again to zero owing to the decreasing and increasing inclination of the light beam relative to the plane of the comparison character. However, the apparatus cannot operate properly unless there is light constantly impinging upon the photosensitive unit except when thelight Ibeam passes through the comparison character corresponding to the character to be explored; For this reason the mirror I9 and the beam reflected by said mirror are so dimensioned with respect to their width that light passes through at least portions of two neighboring comparison characters when the beam center is directed towards the middle between said two neighboring characters, that, however, light passes only through one comparison character when the beam center is directed towards the middle of said comparison character. In consequence thereof, the image of one comparison character will progressively appear on the character to be explored and its light intensity will increase, While the image of the preceding comparison character is still present though fading.

When the light intensity of the comparison character reaches its maximum and, according to the width of the beam, shortly before such maximum occurs, the image .of the preceding character will have entirely disappeared. When the reilected beam continues to rotate the intensity of the image of the comparison character will decrease while the image of the subsequent comparison character will progressively appear. Thus, it will be found, that, according to the width of the reflected light beam, two part images of diiierent comparison characters may be simultaneously created. Even if, in that event, the two part images would combine so as to form an image having the shape of one of the characters to be explored, such occurrence would not interiere with the correct operation oi the apparatus. It is clear that such combination could occur only when the beam center is directed to a point intermediate two neighbored comparison characters. If this is the case, the switch arm 26 oi' Fig. 12 is also in a position between two contacts 2l. Hence, even if under such circumstances the photosensitive unit reacts to permit the passage of current, no current will flow through one of the circuits 21.

However, it will be understood, that the particular type and shape of characters shown in the drawings are selected only by way of example. As i'ar as the device according to the present invention is concerned, the characters as such have no specific meaning. Each character to be explored serves, in a sense, to express a command to the apparatus to energize a co-ordinate circuit 21. Thus, the characters may be chosen from among vthe conventional forms of letters or iigures, or

they may be of any fanciful design. Hence, it is easy to avoid the possi-bility of a combination of the images of parts of two characters into the image of athird character belonging to the group of those to be explored. Furthermore. even it there are in a group two characters, parts of which may form an undesired combination any disturbance can be prevented by so arranging the sequence of the characters, e. g. on the illm of Fig.` 4, -that the two characters under consideration are separated by another one. For fnstance, if the characters of Fig. 4 are used and if it is assumed that a combination of part of the 8 with part of the 9 may form an image similar to the 2 then, any other character of the group, e. g. .the "I or the 1" or the circle may be removed from its illustrated position and arranged between the "8" and "9. This can be done, because the particular sequence of the characters is obviously immaterial with regard to the operation of the device. It is only necessary that ythe sequence of the circuits 21 in relation to switch arm 26 is the same as that of the respectively co-ordinate comparison characters in relation to the rotating beam.

Particular optical phenomena are caused by the rotating beam, owing to the fact that the characters to be explored have a deiinite upright position, and that lthe comparison characters are stationarily arranged about the axis of the beam rotation. If all comparison characters are so arranged as to have equal upright positions, their images on the character to be explored will appear in a position turned with respect to the character notwithstanding a coincidence of the centers of the images and of the character to be explored. lIn order to obtain complete coincidence, only one comparison character may be so arranged that it is in an upright position on cylinder I 4 and that its image appears also upright on the character to be explored. All other comparison characters must be so turned that their center lines which shall appear in their images in upright position are inclined on lm I1' at the cylinder I4. 'I'he correct inclination is deiined by the fact that each comparison character must be turned in relation to the position of the neighboring one about an axis perpendicular t0 the axis of rotation, at an angle equal to that traversed by the beam upon its rotation from one comparison character to the other one. This is exemplified by the development of the nlm ring I1 as shown in Fig. 4. In this gure the ring I1 carries twelve comparison characters II", viz. the numer ls I to Il, an asterisk and a circle. The numer l I" is in upright position and will thus appear on the character to beexplored provided the cylinder I4 with filmV ring I'I' is secured t0 partition I I in the correct position relative to the upright direction of said character. As the twelve comparison characters are arranged on cylinder I4 at equal distances from each other, the numeral 2 is turned 360: 12=30 relatively to the numeral numeral 3 is turned 30 relatively to the 2; etc.

If the apparatus is arranged for twelve different comparison characters as in the embodiment of Figs. 1 to 4, any number of characters up to twelve can be explored with its aid provided the shapes of the comparison characters correspond to those of the characters to be exsuitable comparison characters for cylinder I4.

This may be accomplished by removing the botltom plate 24 with the parts connected thereto, whereupon cylinder I4 may be easily exchanged. If more than twelve characters are to be explored, the sets of mirrors 28, lenses 29, contact elements 25 and comparison characters I'I of cylinder I4 must have at least the same number of elements as there are characters to be explored. In order to adjust the time required for one rotation of the light beam, to the number of comparison characters applied, so that each image prevails suillciently long to cause the photosensitive unit to respond, means may be provided for altering the speed of the drive of the y'rotating member. Such means are indicated by an adjustable resistance 4| in Fig. 12, for adjusting the speed of motor 23.

Figs. 5 and 6 illustrate two modications of the apparatus according to the invention as described hereinbefore. In the modication lof Fig. 5, one rotatable mirror |28 is substituted for the set of stationary mirrors 28 in Fig. 1, and is so arranged that the beam reflected by mirror I9 is directed upon the mirror |28 which rotates synchronously with mirror I9. For this purpose the disc I2I on which mirror I9 is mounted has a larger diameter than disc 2| of Fig. 1, and also -carries mirror |28 outside of cylinder I4. In all other respects the devices of Figs. 1 and 5 are alike. Since, upon rotation of disc I2I mirror |28 takes the position of the individual mirrors 28 of Fig. 1 one after the other, the device operates in the same manner as the embodiment described rst, and the images of the comparison characters will appear and fade on the char:

.acter to be explored in a manner similar to that described with respect to Fig. 1,.provided the dimensions of mirror |28 are suitably selected. 'I'he embodiment of Fig. 5 offers the advantage 4that only one mirror |28 is required for any upon mirror 228 and is reilected in the manner described. The rotation of the disc 22| brings the aperture 2I8 in registry with one comparison character after the other.

Fig. 'l illustrates the preferred form of an apparatus according to my invention. The arrangement of the character carrier .2, photosenstive unit 6, lamp 1, mirror I9, lenses 29, switching device- 8, motor 23, and the housing with parts 9 and I0, partition II and bottom plate 24 are the same as in Fig. 1. However, cylinder I4 of Fig. 1 is lacking, and the stationary inclined mirrors 328 are so designed as to form the comparison characters whose images are to be cast upon the character to be explored. 'Ihe mirrors 328'may be made in various ways. For instance, they may consist each of a highly polished metal plate 329 in the shape of one of the comparison characters, with a standard 338 as shown in Figs. 8 and 9. The standards may be secured to Vring 33| of U-shaped crosssection, and the latter may be mounted on the bottom plate 24. In the modification of Figs. and 11, an inclined plane mirror 332 is covered by a stencil sheet 333. The material of the sheet is light-absorbing, while light will be reected by the mirror surface corresponding to the character 334 of the stencil sheet 333. In order to change the comparison characters of thev apparatus of Fig. 7, either individual characters may be removed by loosening screws 335, or ring 33| with the entire set of characters 328 may be taken oi the bottom plate 24 after screws 336 are removed. The switching elements 25 and the lenses 29 are coordinate to the comparison characters 328 in the same manner as they are coordinate to the characters I1" in Fig. 1.

The operation of the apparatus of Fig. 7 is similar to that of Fig. 1. When lamp I is burning and mirror I9 rotating, a light beam reiiected by said mirror successively passes the reflecting comparison characters 328. Each character reects in its turn a beam having the cross-section of the pertaining character, through the coordinate lens 29 upon the area of carrier 2 which contains the character to be explored in operative position. The images appearing on said area are in the same upright position as character 5, sincethe comparison characters are correctly turned relative to each other as clearly shown in Fig. '7, and as explained hereinbefore with relation to Fig. 4. Owing to the fact that the cross-section of the beam is suiiiciently large to cover at least portions of two neighboring characters when the beam center is directed towardsvthe middle therebetween, the image of a comparison character will appear superimposed upon the character 5 while the image of the preceding comparison character is st1ll in the state of fading. Furthermore, an image of an entire comparison character remains on character 5 as long as the rotating beam impinges upon the whole surface of the pertaining comparsion character. 'Ihe light cast upon said area of character carrier 2 increases to a maximum which holds on for a certain length of time. Thereafter the light decreases. Light will be reflected by said area upon the photosensitive unit except when the image of the comparison characters 328 corresponds to and coincides with the character to be explored. In that instance the unit 6 will respond and cause an electric circuit to pass the switch element 25 coordinate to the pertaining comparison character to operate the actuating device 40 in the pertaining circuit 21. 75

While I havedescribed, in the embodimentsv of lmy invention the use `of a reecting character carrier 'with non-reflecting characters' to be explored. in connection with comparison characters producing light images, the devices according to my invention are operative with equal result if the characters to be explored are light, i. e. reiiecting, on a non-reflecting carrier in connection with comparison characters furnishing dark images on a light background. I consider such reverse as an equivalent of the described embodiments, and desire that the appended claims are understood to include such reverse. changes may be made in the construction and arrangement of the described embodiments without departing from the scope and the vspirit o! the invention.

I claim:

1. In a photoelectric controlling device, including a photosensltive unit, for exploring characters on a character carrier, the combination of a light source, means for moving a light beam oi said source about a predetermined point, a plurality of stationary means for giving the beam u successively cross-sections corresponding to the various characters to be explored, said means being arranged in the path of said moving beam and at an angle thereto so as to be impinged upon by said beam one after the other, means for directing the beam from said last mentioned means upon an area of said character carrier, and lmeans for directing light reflected from said area upon said photosensltive unit so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area.

2. In a photoelectric controlling device, including a photosensltive unit, for exploring characters ion a character carrier, the combination of a light source, means for rotating a light beam originat- 40 ing from said source about an axis and in a predetermined plane, a plurality of stationary means for giving the beam successively cross-sections corresponding to the various characters to be explored, said means being arranged around said axis in the path of the rotating beam so as to be successively impinged upon by said beam, means for directing the beam from said last mentioned means upon an area of said character carrier, and means for directing light reflected from said area upon said photosensltive unit so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area.

3. In a photoelectric controlling device, "including a photosensltive unit, for exploring characters on a character carrier, the combination of a light source, means for moving a light beam originating from said light source in a predetermined plane, a set of stationary comparison characters in the path of said light beam, said comparison characters respectively corresponding in shape to the characters to be explored, and being pervious to light and so arranged as to be passed by said moving beam one after the other, and an optical system for reflecting said beam after it has passed through any one of said comparison characters, upon the area of said character carrier opposite said photosensitive unit, so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area.

4. In a photoelectric controlling device, including a photosensltive Junit, for exploring characters on a character canier, the combination of a light source, means for moving a light beam Other originating from said light source in a predetermined plane, and a set oi stationary mirrors in the path of said light beam, said mirrors having reecting surfaces in the shape of comparison characters respectively corresponding to the characters to be explored, and being so arranged as to be passed by said moving beam one after the other, said mirrors being so inclined as to reflect said beam upon the area of said character carrier opposite said photosensltive unit, so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area.

5. In a photoelectric controlling device, including a photosensltive unit, for exploring characters on a character carrier, the combination of a light source, means for rotating a light beam originating from said' light source about an axis and in a predetermined plane, a stationary-hollow cylinder arranged co-axially with said axis oi' rotation, said cylinder comprising a set of comparison characters pervious to light and arranged in the path of said beam so as to be successively impinged upon by said rotating beam, and an optical system for reecting said beam after it has pass ed through any one of said comparison characters, upon the area of said character carrier opposite said photo-sensitive unit, so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area.

6. In a photoelectric controlling device, including a photosensltive unit, for exploring characters on a character carrier, the combination of a light source, means for moving a light beam originating from said light source in a predetermined plane, a set of stationary comparison characters for giving the beam successively cross-sections corresponding to the various characters to be explored, said comparison characters being arranged in the path of said light beam, and being larger in size than but corresponding in form to the respective characters to be explored, and being so arranged as to be passed by said moving beam one after the other, and an optical system for directing said beam from said comparison characters upon the area of said character carrier opposite said unit, said optical system including means for reducing the cross-sections of said beam at said carrier to the size of the characters to be explored, whereby said photosensltive unit will be enabled to respond when the cross-section of said beam corresponds to a character in said area.

7. In a photoelectric controlling device, including a photosensitive unit, for exploring characters on a character carrier, the combination of a light source, means for rotating a light beam originating from said light source about an axis Aand in a predetermined plane, a set of stationary comparison characters in the path of said light beam, said comparison characters respectively corresponding in shape to the characters to be explored and being pervious to light and so arranged about said axis as to be passed by said beam one after the other, and an optical system comprising a mirror rotatable in synchronism with said beam about said axis of rotation, said mirror being arranged in the path of the beam behind said comparison characters, and being so inclined as to direct said beam permanently on the area of said character carrier opposite said photosensltive unit, so as to enable the same to respond when the cross-section of said beam corresponds to a character in said area. l

8. In a photoelectric controlling device, including a photosensltive unit, for exploring characters on a character carrier, the combination of a light source, means for casting successively light beams originating from said light source from various points of a first closed curve towards the area of said carrier opposite said unit, so that said beams define a cone having its apex approximately in the center of said area, a plurality of stationary comparison characters arranged on a second closed curve concentric with said first closed curve and in the paths of the light beams respectively so as to give eachbeam a cross-section respectively corresponding to one of the various characters to be explored, each comparison char` acter being turned in relation to the position of the neighboring one about the axis of the pertaining beam at an angle equal to the angle which corresponds to the arc of said second closed curve between the two neighboring comparison characters, whereby the images of all comparison characters will consecutively appear on said area in the same upright position, and means whereby light reected from said area is directed upon said photosensitive unit, so as to enable the same to respond when the beam with a cross-section `corresponding to a character in said area impinges upon the latter.

9. In a photoelectric controlling device, including a photosensitive unit, for exploring characters on a character carrier, the combination of a light source, means for rotating a light beam originating from said source about a center in a predetermined plane, a plurality of stationary inclined reecting surfaces in the shape of comparison characters respectively corresponding to the characters to be explored, said comparison characters being arranged on radii in relation to said center so as to be successively passed by said rotating beam and to deect the latter to the area of said carrier opposite said unit, each comparison character being turned in relation to the position ofthe neighboring one about the respective radius at an angle equal to the angle enclosed by the two radii on which the two neighboring comparison characters are located, whereby the images of all comparison characters will appear on said area in the same upright position, and means whereby light reflected from said area is directed upon said photo-sensitive unit so as to enable the same to respond when the beam impinges upon that comparison character which corresponds to a character in said area.

l0. In a photoelectric controlling device, including a photosensitive unit, for exploring characters on a character carrier, the combination of a light source adapted to produce a iight beam having a predetermined axis, a iirst inclined mirror in the path of said beam, means for rotating said mirror about said beam axis, a set of stationary comparison characters in the path of the beam reected by said mirror, said comparison characters relatively corresponding in shape to the characters to be explored and being pervious to light and arranged about said axis so as to be passed by said rotating beam one after the other. and a second inclined mirror in the path of said rotating beam at a greater distance from said axis than said set of comparison characters, said second mirror being rotatable together with said first mentioned mirror and being so inclined as to reflect the beam which has passed through a comparison character consecutively upon the area of said character carrier opposite said unit, so as to enable the same to respond when the crosssection of said beam corresponds to a character in said area.

ll. In a photoelectric controlling device, including a photosensitive unit, for exploring characters on a character carrier, the combination of a light source emitting a beam of light, a rotatable inclined mirror in the path of said beam, a set of stationary comparison characters in the path of said beam reflected by said-mirror, and an optical system for projecting the images of said comparison characters with the aid of said beam towards a predetermined point which is opposite to the sensitive surface of said unit, said photosensitive unit, said light source, said mirror, said set of comparison characters and said optical system having a common axis on which said point is located, whereby the entire device is in operative position with respect to a character to be explored when the center of the latter co-incides with said predetermined point.

l2. In a photoelectric controlling device for controlling a plurality of circuits in accordance with characters on a character carrier, the combination of a photosensitive unit, a light source, a set of comparison characters, an optical system for projecting the images of said comparison characters towards a. character to be explored and positioned opposite the sensitive surface of said unit, a set of connections for said circuits respectively co-ordinate to said comparison characters; said unit, said comparison characters, said optical system and said circuit connections being arranged stationary with respect to each other, and movable means for consecutively directing a beam from said source upon said comparison characters and for connecting said unit to said circuit connections consecutively and synchronously with the movement of said beam whereby a circuit will be energized owing to the unit responding when the beam strikes a comparison character corresponding to the character to be explored.

GEORGE EFRON.

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