US2703280A

US2703280A - Counting circuit control for electrophotographic printers

Info

Publication number: US2703280A
Application number: US162591A
Authority: US
Inventors: Butterfield Louis Boydston; Sulzer John Henry
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1950-05-17
Filing date: 1950-05-17
Publication date: 1955-03-01
Anticipated expiration: 1972-03-01

Description

March 1, 1955 2,703,280

COUNTING CIRCUIT CONTROL FOR ELECTROPHOTOGRAPHIC PRINTERS Filed May 17, 1950 L. BfBUTTERFlELD ET AL 2 Sheets-Sheet l INVENTORS 159x 33. 4502221729 Jkrz Xi jwlzel' 6b fl ATTORNEY March 1, 1955 1.. B. BUTTERFIELD ET AL 2,703,280

COUNTING CIRCUIT CONTROL FOR ELECTROPHOTOGRAPHIC PRINTERS Filed May 17, 1950 2 Sheets-Sheet 2 ATT ORNEY United States Patent COUNTING CIRCUIT CONTROL FOR ELECTRO- PHOTOGRAPHIC PRINTERS Louis Boydston Butterfield, Plainfield, and John Henry Sulzer, Union Beach, N. J., assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application May 17, 1950, Serial No. 162,591

15 Claims. (Cl. 95--1.9)

Thisinvention relates to controls for printing and more particularly to electrostatic printing and electrical controls including a counting circuit for ejecting a microfilm and holder therefor after the microfilm has been cyclically moved through an optical system to produce a predetermined number of electrostatical-ly printed copies from each film.

The recent introduction of the use of electrophotographic printing, while presenting a great theoretical improvement over the existing printing methods, is considerably limited in commercial application because of the complete lack of machinery or apparatus which can utilize the best qualities of the electrophotographic process and yet compete commercially with high speed printers of the many well known types. The present devices utilizing electrophotographic printing are manually operated and require a large number of independent manually performed steps in order to produce a single printed copy. In addition, the available equipment requires a complete reassembly of the printer in order to print copies of more than one desired object.

Consequently, an object of this invention is to provide a high speed printer of the electrostatic or electrophotographic type wherein the objects to be printed are automatically fed into the printer and subsequently ejected upon completion of a predetermined number of printed copies.

In accordance with this and other objects, one embodiment of the invention comprises a reciprocating carrier which is adapted to cyclically move a microfilm and holder through a beam of light in an optical system so as to produce variations in light intensity which are subsequently applied to a photoconductive printing surface to generate electrostatic images thereon. A photoelectric cell is positioned adjacent the moving holder to be energized thereby for producing pulses of current which are totalized in a counting circuit adjusted so as to eject the moving microfilm and its holder upon completion of a predetermined number of movements of the film. Also, the photoelectric cell energizes a circuit which controls a printing surface actuating means so that this surface moves only during the same intervals of time as the moving microfilm.

A more complete understanding of the invention may be had by consideration of the following detailed description in conjunction with the accompanying drawings wherein Fig. l is a schematic view of an electrophotographic printer disclosing the invention;

Fig. 2 is a circuit diagram of a counting circuit for controlling the apparatus of Fig. 1;

Fig. 3 is a plan view of a microfilm and a holder therefor in printing position; and

Fig. 4 is a side elevational view of the microfilm and holder in printing position.

Referring now to Fig. 1 of the drawings, a photoconductive printing roll 11 is driven by an electric motor 12. The term photoconductive as used in this application means those materials having such a change in their electrical characteristics in the transition from darkness to light that an electrostatic image can be produced and maintained by said materials during an electrostatic printing cycle. Such materials include amorphous selenium, sulphur, germamium, lead sulphide, copper oxide, silver chloride, silver iodide, various combinations of-selenium and sulphur and pthers.

2,703,280 Patented Mar. 1,1955

A pair of receptacles 13 and 14 are rigidly secured opposite each other and adjacent the periphery of the printing roll 11. Receptacle 13 contains a color pigment which is used to print a desired color image and receptacle 14 encloses a brush which is used to clean the surface of the printing roll 11 after each printing operation. A supply roll 15 of paper positioned adjacent a lower sector of the periphery of the printing roll 11 feeds a continuous web of paper to the roll 11 for receiving the desired color image to be printed.

Three spaced groups of electrostatic charging wires 16, 17 and 18 are positioned adjacent three separate portions of the roll 11. The wires 16 are used to place a uniform electrostatic field on the surface of the photoconductive roll 11 and the wires 17 transfer the color pigment image from the surface of the roll 11 to the surface of the paper web supplied by the roll 15. The wire group 18 appliesan electrostatic field of a polarity reversed to the field produced by the wire group 16 on the photoconductive surface of roll 11 so as to reduce the fatigue thereof or to prevent breakdown of the photoconductive characteristics. The fatigue elimination effect of the wire group 18 is described more fully and also is claimed in a copending application of Butterfield and Claybourne, Seriai Number 162,592, filed May 17, 1950.

An electric bulb 19 provides a source of light which is focused on a moving microfilm 20 (Figs. 3 and 4) by a lens 21. A movement of the microfilm 20 through the focused light produces variations of intensity in the light which has passed through the film 20. These variations in light intensity are then transmitted through a light restricting slit 22 (Figs. 3 and 4), through an enlarging lens 23 and are finally reflected onto the photoconductive surface of the roll 11 by mirrors 24 and 25. These light variations when applied to the photoconductive-surface of the moving roll 11 generate an electrostatic image which is proportional to the variations in light intensity received on the uniformly charged photoconductive surface of the roll 11.

The rotation of the roll 11 carries the progressively formed electrostatic images through the color pigment receptacle 13 wherein the electrostatic charge on the roll 11 attracts and holds the color pigments to form a color image on the surface of the roll 11 which image is subsequently transferred to the paper web by the electrostatic field of the wire group 17. Following the transfer of the color image by the electric field of the .Wire group 17, the surface of the roll 11 is cleaned in the receptacle 14, charged by an electric field produced by the wires 18 to reduce fatigue, and finally charged by the wires 16 to produce a uniform electrostatic field which is moved into the field of the light variations once again to produce another electrostatic image. The foregoingsteps of the electrostatic printing process are carried on in an endless sequence through the continuous start-stop rotation'of the printing roll 11.

Microfilm feeding control centrally mounted. Since the film 20 is recessed from both the upper and lower surface of the film holder 29, there is no danger of damaging the surface of the film 20 by accidental abrasion or rubbing. Each of the holders 29 is also provided with two spaced vertical holes 41 and 42 (Figs. 3 and 4) which are positioned adjacent one edge of the holder 29.

An L-shaped carrier 43 having two vertical holes 44 and 45 (Figs. 3 and 4) and a vertical central opening 46 rests on the top surface of the frame 26 and is adapted to be reciprocated thereon. An arm 47 issecured to the left end of the carrier 43 and extends parallel to the upper surface of the frame 26. A pin 48 is rigidly secured to the left end of the arm 47 and projects perpendicularly therefrornto engage within thebifurcations of aforked end 49 on an upright arm 50. The arm 50 is reciprocated by a drive 60 which may be any one of the numerous well-known types such as an eccentric system driven by an electric motor.

The reciprocating drive 60 is controlled by a spring pressed contact 61 which connects a source of power 62 to the electric motor of the drive 60 through the conductors 63, 64 and 65. The contact 61 is secured to the rack 28 in such a manner that this contact is held closed to supply power to the drive 60 as long as a film holder 29 remains in the rack 28. When the last film holder 29 which does not contain a film 20 is removed from the rack 28, a spring 66 forces the contact 61 open and the reciprocating drive 60 is stopped.

The initial operation of the drive 60 is accomplished by dropping a holder 29 into the rack 28 to be held therein by the detent 30 so that the contact 61 is closed by the holder 29 against the action of the spring 66. The additional films 20 to be printed and their associated holders 29 are stacked on top of the first placed holder 29. Operation of the drive 60 reciprocates the arm 50 thereby causing the carrier 43 to move through an oscillatory cycle between a position beneath the rack 28 and a position over an edge of the recess 27.

The operation of the drive 60 actuates the arm 50 to move the carrier 43 under the rack 28 whereby an edge of the upper surface of the carrier 43 moves the detent 30 out of its normal position to allow the first holder 29 to drop onto the carrier 43. When the holder 29 is in place on the carrier 43, the holes 41, 42 and opening 40 are aligned with the holes 44, 45 and opening 46, respectively, in the carrier 43. The reciprocating arm 50 then continuously moves the carrier 43 and the holder 29 with a microfilm 20 over the light slit 22 in the frame 26 to scan the microfilm 20 and make one printed copy thereof. If only one printed copy is desired, the holder 29 and its film 20 is then ejected into the recess 27. However, where more than one printed copy is to be made, the particular holder 29 and film 20 must be reciprocated in the carrier 43 past the light slit 22 to accomplish the desired number of scanning operations. When, in the event that more than one copy is desired, the carrier 43 and holder 29 return to a position beneath the rack 28, the detent 30 is again engaged. However, the lowermost holder 29 will not drop onto the carrier 43 at this time inasmuch as the former holder 29 is still on the carrier 43. The above de scribed cycle of operation is repeated until the holder 29 being moved by the carrier 43 is eiected therefrom. At this time, movement of the carrier 43 to engage the detent 30 releases another holder 29 which falls into the space on the carrier 43 occupied by the previous holder 29.

A switch 67 (Fig. 3), positioned on the frame 26 and in the path of movement of the carrier 43, is closed by a forward movement of the carrier 43 an instant before the leading edge of the film 20 registers with the slot 22 and remains closed until it is opened when the carrier clears or passes the switch and is maintained opened during the entire reverse movement of the carrier 43 toward the rack 28. The switch 67 interconnects the electric light bulb 19 with a battery 68 through conductors 69 and 70 so that the bulb 19 will only be illuminated during the forward movement of the carrier 43 when the microfilm 20 is scanned. Therefore, the films 20 are scanned to produce light variations on the photoconductive surface of the roll 11 only during the forward movement of the holder 29 and, consequently, any scanning during the return movement of the carrier 43 toward the rack 28 is prevented.

A slit 80 in the frame 26 (Figs. 3 and 4) is so positioned below and in alignment with the path of travel of the aligned holes 42, 45 and the aligned holes 41, 44 that a beam of light from the bulb 19 will pass through each hole in sequence and through the slit 80 to impinge on a photoelectric cell 81 therebeneath. Since the bulb 19 is energized after the switch 67 is closed by the forward movement of the carrier 43 the only light incident upon the slit 80 and, consequently, upon the cell 81 is that which passes through aligned holes 42. 45 and aligned holes 41, 44 as they pass over the slit 80 on the forward stroke of the film holder 29. The distance between the slits 22 and 80 is the same as that between the leading edge of the microfilm 20 and the leading edge of the hole 42 so that the first beam of light striking the photocell 81 will correspond exactly in time with the incidence of the first beam of light which passes through the microfilm 20 to be reflected by the mirrors 24, 25 and then impinged on the printing roll 11. The distance between the trailing edge of the microfilm 20 and the leading edge of hole 41 is so positioned that the cell 81 is energized simultaneously with the completion of the scanning of the microfilm 20.

Printing roll control The incidence of the first beam of light on the cell 81 produces a pulse of current which is transmitted to a photocell amplifier 82 by a conductor 83. The amplifier 82, when energized by the photoelectric cell 81, produces a ground pulse which is applied by a conductor 86 to a contact 84 of a relay 85. The ground pulse transmitted from the amplifier 82 by the conductor 86 is also applied through a normally closed contact 87 of a relay 88 to and through a resistor 89 and a battery 90 to ground. The ground pulse applied to the contact 84 completes a circuit from ground through a battery 100, a resistor 101, the operating coil of the relay 85, the contact 84, and thence to ground in the amplifier 82 through the conductor 86. Completion of this circuit operates relay 85 from the battery so that

contacts

102, 103 and 104 close and the contact 84 opens. Relay 88 remains unoperated throughout the duration of the first ground pulse since the ground on contact 84 is shunted around the operating coil of relay 88 by the closed contact 87.

The operation of relay 85, although removing the ground by opening contact 84, closes a holding circuit comprising grounded contact 104, now closed, the operating coil of relay 85, resistor 101, and battery 100. This holding circuit maintains the relay 85 operated after ground is removed from the contact 84. The closure of contact 102 provides ground through a conductor 105 to an operating coil of a relay 106 and thence through a battery 187 to ground so that the relay 106 is operated to close contact 108. The contact 108 is in series with an external power supply 109, shown here as a transformer, and with the motor 12 for actuating the printing roll 11. The operation of relay 106 to close contact 108 energizes the motor 12 to rotate the roll 11 and since the original ground pulse operating the relay 85 and, subsequently, the relay 106 was initiated by light passing through the aligned holes 42 and 45, which holes register with slit 80 simultaneously with the leading edge of the microfilm 20 passing over the slit 22, the roll 11 begins to rotate at the exact moment that the microfilm 20 moves across the slit 22 to produce the first light variations for generating the electrostatic image on the surface of the roll 11.

The closure of contact 103 connects ground through a contact 110 of the relay 88, conductor 120, contact 103, through a conductor 121 to an operating coil of a stepping relay 122 (Fig. 2) and thence to grounded battery 123. As long as this circuit remains closed, the relay 122 will be held operated by the battery 123.

Referring again to the carrier 43, the continuing movement thereof toward the recess 27 moves the holes 42 and 45 out of alignment with the slit 80 so that the cell 81 is no longer energized by light from bulb 19 and, consequently, the ground pulse produced by the amplifier 82 is removed from the conductor 86. The removal of ground from conductor 86 removes the shunt around the operating coil of relay 88 through contact 87, and the relay 88 is then operated by a circuit extending through contact 104, now closed, a conductor 124, the operating coil of relay 88, resistor 89, and battery 90. Operation of relay 88 opens the

contacts

87, 110 and closes a contact 125. The opening of contact 110 breaks the circuit comprising ground, contact 110, conductor 120, contact 103, conductor 121, the operating coil of a stepping relay 122 (Fig. 2), and battery 123, whereby the relay 122 is released.

Operation of the relay 88 does not affect the continued energization of the motor 12 so the roll 11 continues to rotate in synchronism with the movement of the film carrier 43 past the slit 22 so that the progressively formed light variations at the slit 22 are continually applied to a new portion of the surface of the printing roll 11. However, as the carrier 43 and microfilm 20 reach the point at which the trailing edge of the microfilm 20 passes the slit 22, the holes 41 and 44- reach alignment with the slit 80 so that once again the cell 81 is energized by light energy from the bulb 19.

As previously described, the cell 81 energizes the amplifier 82 to produce a ground pulse which is applied through conductor 86 to the contact 84. The ground pulse of conductor 86 is applied through contact 125. now closed by the operation of relay 88, to theresistor 101, battery. 100and 'tlierethrougli toground to form a ground shunt aroundtheoperating coil of relay 85. Since relay 85, isthus deprivedot cnergization from the battery 100, the relay,85 releases and, consequently, opens

contacts

102, 103 and 104, while closing contact 84.

Relay 88 remains operated although ground is removed trom the operating coil thereof by the opening of contact 104-because the contact 84 is now closed and the operating coil of the relay 88 is energized by theground pulse from amplifier 82 which is transmitted through conductor 86, contact 84, the operating coil of. relay 88, resistor 89 and finally through battery 90 to ground.

The opening of contact 103. opens the voperating path for energizing the stepping relay 122' of Fig. 2 to prevent relay 122 from operating when relay 88 releases.v

The opening of contact 102 breaks thecircuit energizing the relay 106 so that contact 108 opens and subsequently removes the energization from the driving motor 12 to stop rotation of the printing roll 11. Since the aligned holes Y41 and 44' are placed adjacent the end of the microfilm 20, the pulse initiatingthe removal of the driveto the printingroll 11 occurs simultaneously with the end of the scanningprocess so that rotation of the roll 11 ceases as soon as the entire film 20 has been scanned.

A slight movement of the carrier 43 and the film 20 toward the recess 27 and beyond the slit 22 moves the holes 41 and 45 out of alignment with the slit 80 so that light from the bulb 19 no longer energizes the photoelectric cell 81. As described hereinbefore, removal of the energizationof'cell 81 renders the amplifier 82inoperative to produce a ground pulse and the ground is subsequently removed from the conductor 86 and contact 8 This removal ofground from contact 84 breaks the circuit comprising ground, battery90, resistor 89, and conductor 124 so that relay 88 releases and opens contact 125 While

closing contacts

87 and 110. As soon as the relay 88 is released, the circuit comprising relays 85 and 88 is conditioned for another two ground pulse cycle exactly the same as that just described. Since switch 67 is open on the return stroke of the carrier 43, the light bulb 19 will not be energized and the holes 41, 42, 44 and 45 passing over the slit 80 fail, therefore, to produce any energization of the cell 81.

Counting circuit and ejector The pulses applied by the relays 85 and 88 to the conductor 121 energize the stepping relay 122 (Fig. 2) to initiate a counting circuit which controls the number of printed copies to be made of a particular microfilm 20.

The stepping relay 122 (Fig. 2), which is energized by the operation of the relay 85 and released. by the operation of the relay 88, advances two pairs of

contact making arms

126, 127 and 128, 129 which are rigidly secured to a single shaft to move simultaneously and close an off-normal switch 130. The switch 130 is arranged so that the initial movement of the

arms

126, 127, 128, 129 closes the switch 130 and the return of the

arms

126, 127, 128, 129 to a normal home position opens the switch 130.

Arms

126 and 127, which are electrically interconnected, complete a circuit between a conducting ring 131 and a plurality of contacts 140 which are arranged in a semicircle to be progressively contacted, step by step, upon each advance of the arm 126. The arms 128 and 129, which are electrically interconnected, complete a circuit between a conducting ring 132 and a plurality of contacts 141 which are arranged in a semi-circle to be progressively contacted by each advance of the arm 128.

The contacts 140 are adapted to be connected to ground through a plurality of switches 142 which are singly connected in parallel with ground through a conductor 143. The switches 142 represent the digits 19 and zero in the units denominational column, the uppermost switch 142 representing the digit one 1) and the lowermost switch 142 representing the zero or cipher, and the other intervening switches 142 representing the digits two to nine (2-9), inclusive. Anyone of the switches 142 may be closed to connect the respectively associated contact 140 to ground in accordance with the particular digit desired to be registered in the units denominational column. Although the contacts 140 are shown as being manually grounded through the switches 142, they also may be grounded by any of the grounding circuits which are controlled by punched cards or punched tapes as disclosed in'a copendin'g application of Butterfield 6. and.SulZer, Serial No. 186,008 filed.September .21,'- 1950, now Patent No. 2,641,997, issuedJune 16,1953.

The operation of the off-normal switch on receipt of the first pulse from. the relay 122 closes

contacts

144 and 145, which contacts remain closed until the relay 122 is reset to the normal home position. Contact 145, when closed, connects ground to. a pair of open contacts 146 and 147 of a relay 148 through a conductor149; Contact .144, whenclosed, connectsbattery 150 to the wind ing of a reset relay 161. A contact 162 is: adapted to be connected to ground through..a conductor 163 and a normally closed contact 164 of a normally operated relay 165. 'lhe relay 165 isoperated by an energizing circuit comprising ground, a.normally closedcontact 166 of a relay 167, aconductor 168, theoperating coil'of relay 165, and a grounded battery 169.

As hereinbefore explained, the pulsesthroughthe con ductor 121 energize the relay 122 to progressively advance the arm 126 over the contacts .140. When the arm 1'26 advances to a contact.140 which is grounded through switch 142 and conductor 143, a..circuit is completed from ground through conductor.143, switch 142, arm 126, arm 127, ring 131, a conductor. 170, a contact of the relay 165, a conductor181, the operating coil ofrelay 148, and thence through groundedbattery 182. This circuit energizes the relay 148 to close

contacts

146, 147, 162, 228 and a contact 183.

The closing of contact 146 by the operationv of relay 148 completes a holding circuit for the relay 148 throughv ground, switch 1.30, contact .145, conductor 149, contact 146, the operating coil of relay 148,. and grounded battery 182. the arm 126 is moved away from the grounded contact 140 and also prevents the relay 148 from. openingin the event that grounding switch 142 is inadvertently or prematurely opened. Contact 147, in closing, completesa holding circuit for the relay 165 through ground, switch.

1311, contact 145, conductor-149, contact 147,.conductor 168, the operating coil, of relay 165,.and grounded battery 169.

Contact 183, when closed, completes acircuit from ground through. a conductor 184, through the. operating coil of an ejector (Fig. 1) for ejecting a film holder 29 off the carrier 43, and-finally through a battery 186 to. ground. This circuit energizes the operating. coil of. the ejector 185 so that an armature 187, thereof, moves.

downward to strikethe holder 29 which is. now posi tioned directlyunder the armature 187 so asto. force the holder. 29 out of the carrier 43 and into therecess 2.7. Therefore, the operationof the relay 148 by the arm 126 reaching a predetermined grounded contact140 causes the ejection of the microfilm 20 and holder 29.

in response to a predetermined number of counted movements of the film 21).

Contact 162, when closed by therelay 148, energizes the reset relay 161 through a circuit comprising ground, contact 164, conductor 163, contact 162,-conductor 151, operating coil of relay 161, .contact 144, switch 130, and grounded battery 150. Operation of therelay 161 causes the

arms

126, 127, 128, 129 to return to their normal home position, i. e., the position before receipt of any pulses, and the homing movement of

thearms

126, 127, 128, 129. causes the off-normal switch 130 to. return to its normal home position, thus opening the

contacts

144 and 145. The opening of contact 145 breaks the holding circuit associated with relay 148 thus causing the relay 148 to open

contacts

146, 147, 162, 183. and to break the holding circuit of relay 165. However, since the contact 166 of relay 167 remains closed, the relay 165 remains operated by the ground provided through the contact 166. and the conductor 168. The

opening of contact 144 breaks the energizing circuit of the reset relay 161 thereby allowing advance .ofv the

arms

126, 127 128, 129 upon receipt of future Pulses by the stepping relay 122.

The opening of the contact 183, ,by the release of relay 143 breaks the energizing circuit of the ejector185 and the armature 187 thereof returnsto a normal position. The opening of contacts 146, 147 and 162 conditions the relay 148 for another cycle of pulse counting. In effect, therefore, the energization of the reset relay 161, upon ejection of the microfilm 2t) and holder 29, conditions the counting circuit for another complete counting cycle.

In order to count more than the ten pulses made available by the tencontacts 140, asecon'dstepping relay This circuit holds the relay 148. operated after 188 representing the digits in the tens denomination column is connected to be energized by completion of a circuit extending from ground through conducting ring 132, arms 128 and 129, contact 141, conductor 189, the operating coil of relay 188, a battery 190, and thence to ground. Relay 188 is similar to relay 122 in having two pairs of electrically

interconnected arms

200, 201 and 202, 203 which are mounted for simultaneous rotation. An off-normal switch 204 is arranged, as in relay 122, to close two contacts 205, 206 upon receipt of the first pulse to be counted and to open the contacts 205, 206 upon return of the

arms

200, 201, 202, 203 to their normal home position.

The arm 200 completes a circuit from a plurality of contacts 207, through the electrically interconnected arms 200 and 201, to and through a ring 208 which is connected to the operating coil of the relay 165 by a conductor 209 and the conductor 168. The contacts 207 are arranged to be selectively grounded by a plurality of switches 210 which are connected in parallel to ground by a conductor 220. The switch 210 may be replaced by automatic electrical grounding circuits controlled by punched cards or punched tapes which are shown and described in the copending application of Butterfield and Sulzer referred to in conjunction with the previous descri tion of the groundin of the contacts 140.

Each of the contacts 207 is also connected through one of a plurality of parallellv connected resistors 221, to and through a conductor 222. to the operating coil of the relay 167, and therethrough to ground throu h a battery 223. The value of the resistors 221 is set high enough that the marginal relay 165 cannot be operated by a current from ground passing through two resistors 221 in series and thence throu h the arms 200 and 201 to the operating coil of the relay 165. This selection of the value of ma nitude for the resistors 221 prevents a premature operation of the relay 165 when the arm 200 advances to a contact 207 which is not directly grounded by its associated switch 210 but which is grounded throu h two seriallv con ected esistors 221 and a closed swi h 210 associated with a different contact 207.

The arm 202 completes a circuit from a plurality of e ectrically interconnected cont cts 224 through the arms 202. 203 and a contact ring 225 to a reset relay 227. The electricallv interconnected contacts 224 are adapted to be connected to a contact 228 of the relay 148 thr ugh a conductor 229.

The closure of contact 205 by the o eration of ottnormal switch 20 connects a battery 2 from ground throu h c ntact 205 to the reset relay 227. The simultaneous closing of contact 206 connects conductor 189 to an operating coil of a relav 240 through a conductor 241 and hence to a ground through a battery 242. A contact 243 of the relay 240, when operated connects ground throu h an o erating coil of a relay 244 to and throu h a ba ery 245 to ground. A contact 246 of the relay 244. when operated, connects ground to winding of reset relay 161.

Referrin now to the switches 210. the top switch 210 re resents he di it one (1) in the tens denominational column while the lowermost switch 210 represents zero in the tens c lumn. The intervening switches 210 re resent the di its 2 t 9, inclusive, in the tens denominational column. When any one of the switches 210 is closed. a circuit is completed from ground. throu h conductor 220. switch 210. resis r 221. conductor 222. the operatin coil f the relay 167, ba tery 223. and back to round. This circuit ener izes the onerating coil of the relav 167 to open contact 166. The open ng of contact 166 breaks the circuit comprisin ground, contact 166. c nductor 168. the operatin coil of relay 165. batterv 169. and ground, so that relay 165. normally oper d. releases and in doing so opens

contacts

164 and 180.

Therefore. even though one of the switches 142 i closed. the relav 148 cannot be operated from ground through the c nt ct 180. now open. and hence the arms 126 and 128 index to the tenth contacts 140 and 14 1. resnectivelv. As arm 128 advances to the tenth con act 141.. a circuit is com leted from ground throu h ring 132, arms 129 and 128. contact 141. conductor 189. the operating coil of the relay 188. battery 190, and back to ground. whereby the relay 188 is operated to advance the

arms

200, 201, and 202, 203 from the normal home position to the first contacts 207 and 224, respectively.

The movement of the

arms

200, 201, 202, 203 also operates the off-normal switch 204 to close contacts 205 and 206. With contact 206 closed, a circuit is established from ground through the ring 132, through arm 129, arm 128, contact 141, conductor 189, contact 206, conductor 241, the operating coil of relay 240, battery 242 and back to ground, whereby the relay 240 is operated to close contact 243. Contact 243, closed, completes a circuit from ground through contact 243, through the operating coil of relay 244, and then through the battery 245 to ground so that relay 244 is operated to close contact 246.

Contact 246, in closing, connects ground to the reset relay 161 through conductor 247 so that the relay 161 is energized by the battery through the closed contact 144 of the oif-normal switch 130. Energization of the reset relay 161 returns the

arms

126, 127, 128, 129 to their normal home position and conditions the relays 122, 148, and for another cycle of pulse counting as hereinbefore described. The return of the arms 128, 129 to the normal home position removes the ground from the conductor 189 so that relays 240 and 244 release to condition the stepping relay 188 for receiving another pulse through ground from contact 141.

The process of counting ten pulses to advance the

arms

200, 201, 202, 203 to another contact 207 is repeated as described above until such time as the arm 200 advances to a contact 207 which is grounded through the switch 210 and conductor 220. As arm 200 engages a grounded contact 207, ground is applied through conductor 220, switch 210, contact 207, arms 200, 201, ring 208, conductors 209 and 168, the operating coil of relay 165, and finally through battery 169 to ground so as to operate relay 165. The operation of relay 165 to close contacts 164 and conditions relay 148 for operation the next time the arm 126 advances to a grounded contact 140 and also indicates that the counting has been completed in the tens denominational column.

As described above in conjunction with the resetting of the counting relay 122 in the unit denominational column by completion of the first count in the tens denominational column the relays 240 and 244 connect ground to the reset relay 161 to return the

arms

126, 127, 128, 129 to normal home position and to open the off-normal switch 130. The relay 122 then advances the

arms

126, 127, 128, 129 until arm 126 touches a grounded units contact 140 so that the relay 148 is energized by a circuit comprising grounded battery 182, operating coil of relay 148, conductor 181, contact 180, conductor 170, ring 131,

arms

126 and 127 contact 140, switch 142, con ductor 143, and back to ground. Operation of relay 148 closes the

contacts

146, 147, 162, 183 and 228 associated therewith.

The closing of

contacts

146, 147, 162 and 183 again performs the same function as described hereinbefore in conjunction with the explanation of the operation of the relays 122, 148, 161 and 165 when only a unit denominational number of pulses are counted. The closing of contact 228 completes a circuit for energizing the reset relay 227 from ground, through contact 164, conductor 163,

contacts

162 and 228, conductor 229, contact 224,

arms

202 and 203, ring 225, the operating coil of relay 227, contact 205, and grounded battery 230. Operation of the reset relay 227 moves the

arms

200, 201, 202, 203 to the normal home position and releases the off-normal switch 204. The opening of contacts 205 and 206 by the release of switch 204 completes the conditioning of the entire 0 unting system for the receipt of a new series of ground pulses on the conductor 121 from the relays 85 and 88.

In the special situation where the number to be counted, as determined by the settings of the switches 142 and 210, is an even tens digit; i. e., 20, 30, the reset relay 227 is energized through the contact 162 rather than through the contact 246 since the combined operating time of relays 148 and 165 is much less than the combined time of operation of the relays 240 and 244. It is apparent that the range of the counting circuit can be extended into higher denominational columns by the addition of any desired number of groups of stepping relays similar to those shown and described in this particular embodiment.

General operation of the system In view of the foregoing detailed description, it is 9; believed that the operation of the printing and feeding apparatus will now be understood. The. number of copies of the microfilm 20 desired to be printed is controlled manually by an operator or attendant setting the switches 142 and 210 so as to ground particular contacts 140 and 207. For example. if it is desired to print 21 copies of a particular microfilm 20 the digit 1 contact 140. inthe units denominational column is. grounded by the operator closing-the switch142. and the digit 2 contact 207 in the tens denominational column isgrounded. by the operator closing switch 210. When switch 210. is closed, the relay 167 is operated from ground through resistor. 221, conductor. 222,v the operating coil ofrelay 16.7, andthence through battery 223. to ground so;that contact 166 opens to remove ground from the operating coil of the relay 165.- Removal of ground from the operating coil of relay 165 releases contacts 164 and180 thereof and indicates to the counting circuit that there is a digit entered in the tens denominational column to be countedby the relay 188. beforethe relay 165. is operated again.

The microfilm 20, whichis. desired to be printed, and its holder 29. are placed in the rack 28. Any. additional microfilms 20. to be printed are placed in individual holders 29 which are stacked intherack 28 on top of the firstiplacedholder 29; An empty holder 29 is then placed on top of the stack in.therack.28 to. hold the switch 61. closed. while the. last film 20 is being printed.

Thefirst placed holder 29 at the bottom of the rack 28 closesthe switch 61 to. complete the power supply circuitrto the motor for the reciprocating'drive 60 whereby the carrier 43, now empty, moves .towardtherack 28. Whendirectly beneath therack 28,.the carrier 43.strikes the detent 30. to. release the first. microfilm holder 29, which drops in proper position on the carrier 43. The reciprocating drive: 6.0,,having. reached the reverse end of itscycle ofmovement,nowmoves the carrier 43 toward the recess 27 andthereby. permits thedetent 3.0 to return to normal position and to engage the. next holder- 29. inthe rack 28. whereby the switch 61.15;.(1'1311'11311161 closed tov supply energy to. themotor. of. thedrive 60. As the carrier 43 moves toward. the recess 27, the switch 67 is closed to energize the, light bulb, 19 fromthe battery 68so, that whenthe holes 4,2..and 45. move into simultaneous alignment with the slit 80 andrthe leading edge of the microfilm 20 is. in alignment with the slit 22, a beam of light passesthrough the. microfilm 20. and holes 42 and 45'for energizing boththe photoconductive surface of printing roll 11 andthe control circuits.

The light energy from the bulb 19 istvaried in inten-. sity in passing through the microfilm 20. andis. subsequently magnified. by the lens. 23, and refiected onto the photoconductive surface of the roll 11 by the mirrors 24 and 25. These light variations generate an electrostatic image on the surfaceof .the roll 11. Simultaneously with the application of the light variation to, the roll 11, a beam of, light passing through the slit 80 energizes. the photoelectric cell 81to trigger the amplifier 82 to. produce a ground pulse on theconductor 8.6. Thisjground on the conductor 86 isapplied through the contact 84. to energize the relay 85, which, in operating, closes its associated contacts.102, 103.and 104. The contact 102, in closing, operatestherelay 106 to close the contact 108, which then energizes the printing ro l motor 12 from the energy source 109. Therefore, the printing rollll is. rotated by the motor 12. at the same instant with respect to time as the original instant. of incidence of the light variations ,on the roll 11.

Contact 103, when closed, applies a ground to the relay 122 through the conductor 121 so that the relay 122, is operated from battery to. advance the arms..1 26, 127, 1 28, l29fand'to close the off-normal switch 130. The relay 148 is not operated at this time, although the arm 126 is advanced one step. to touch the first contact 140- which has been grounded. by the switch 142, because. the relay 165 has been previously released by the, operation of relay 167.

The continuing movement of the carrier 43 advances the holes 42 and 45 out of alignment with the slit 80 thereby shuttingofi the beam of light and. the cell 81 is thus deprived of energization so. that the ground is removed from the conductor 86. by the amplifier 82. The removal of ground'from the conductor86 operates relay 88 to close'contact 12S"and.to opencontacts 87 and 110; Opening contact 110 breaks the ground circuit throughthe conductor 121 to the relay 122 so that relay 122. returns to an unoperated state in condition for receipt of the next pulse. In addition, the continuing forward movement of the carrier43 advances new portions of the microfilm 20 past the slit 22 so that light variations representative of the entire area of the film 20 are progrelsslnllely applied to the photoconductive surface of the rol When the carrier 43 is advanced so that the trailing edge of the microfilm 20 arrives at the slit 22, the holes 41 and 44 are aligned with the slit 80 to allow a beam of lightfrorn thebulb 19 to energize the cell 81. The energization of cell 81 once again connects ground to the conductor 86 so that relay 85 is released by virtue of the ground shunt around its operating coil completed through contact 125, now closed. The release of relay 85 opens

contacts

102, 103 and'104, whereby contact 102 opens the energizing circuit of the relay 106 and subsequently disconnects power from the motor 12 through the opening of the contact 108 controlled by the relay 106. In this manner, the printing roll 11 stops rotating at the same instant that the trailing edge of the microfilm 20 passes over the slit 22.

As the carrier 43 moves on toward the end of the forward cycle, the holes 41 and 44 move out of alignment with the slit 80 and the cell 81 is no longer energized so that once again the ground is removed from the conductor 86 and the relay 88 is released. in releasing,.relay 88 completes the conditioning of the relays 85and 88 for receipt of the next ground pulse on conductor 86.

When the carrier 43 clears switch 67 the light bulb 19 is extinguished. Upon reaching the end of the forward cycle, the carrier43 reverses direction to move toward the rack .28 but, asthere is no source of light to energize the photoconductive surface of the roll 11 or the cell 81, there will be no image on the roll and no control pulses in the amplifier 82. The carrier 43 then moves into position-beneath the rack 28 once again and moves the detent 30 to release the next holder 29. However, the original holder 29 is still in position on the carrier 43 and the holder 29 in the rack 28 remains therein. As carrier 43 reaches the end of the reverse cycle of movement, the drive 60 moves the carrier 43 in a forward direction toward the recess 27 and in doing so the detent 30 closes to securethebottom holder 29 in position on the rack 28.

The above described cycle of operation is repeated eight more times until on the tenth forward movement ofthe carrier 43, the relay 122 is energized to advance thearm-128 to engage the tenth contact 141 whereby a circuit is completed from ground through ring 132, arms 129 and 128, contact 141, conductor 189, the operating coil. of-relay; 188, and grounded battery 190. Completion of this circuit operates relay 188 to advance the arms 200,- 201, 202, 203 oneposition from the normal home position and also to close the off-normal switch 294. The operation of switch 204 closes contact 206 to initiate successive operation of therelays 240 and 244 for connecting ground to the reset relay 161. The reset relay 161, when energized, returns the

arms

126, 127, 128, 129 to normal home position and releases the oil-normal switch 130, whereby the relay 122 is conditioned to receive a; new cycle of ten pulses.

Onceagain the relays 85-and 88 operate in response to ten additional forward or scanning movements of the carrier 43 so that the arm 128 is'again moved to engage the tenth contact'141 and completes an energization circuit forfthe relay 183. When relay 188 receives this second pulse, representing the twentieth forward or scanning movementof the carrier 43, the arm 200 is advanced to engage the; grounded digit 2 contact 297 so as to complete a. circuit from'ground through conductor 220, switch 210,- contact 207, arms 20%! and 201, ring 208, conductors 209 and 168, the operating coil of relay 165, and grounded battery 169. This circuit operates relay 165 to close: the

contacts

180, 164 and indicates that the tens denominational column requirement (20 counts) has been fulfilled so that the next time the arm 126 engages the'grounded contact the ground will be applied to the operating coil of relay 148. The reset relay 161 is again energized by the relays 240, 244 to reset the

arms

126, 127, 128, 129 to the normal home position and also ot open the off-normal switch 130.

As. the carrier. 43 makes'the next forward movement; i. e., the twenty-first, the arm 126 is advanced by relay 122 to touch the grounded first contact 140 and thereby completes the energizing circuit of relay 148 comprising ground, conductor 143, switch 142, contact 140,

arms

126 and 127, ring 131, conductor 170, contact 180, conductor 181, the operating coil of the relay 148, and grounded battery 182. The operation of relay 148, closes

contacts

146, 147, 162, 183 and 228. The closing of contact 162 completes a circuit from ground to operate the relay 161, which, when operated, returns the

arms

126, 127, 128, 129 to normal home position and also opens the off-normal switch 130. The closing of contact 228 completes a circuit from ground through the operating coil to operate the relay 227, which, when operated, returns the

arms

200, 201, 202, 203 to the normal home position and also opens the off-normal switch 204. With both

relays

122 and 188 reset, the counting circuit is conditioned for another complete counting cycle in accordance with the permutation of switches 142 and 210 that are to be closed by the operator to control the next desired number of copies to be printed.

The contact 183, when closed, completes a circuit from ground through contact 183, conductor 184, ejector 185, battery 186, and thence to ground whereby the ejector 185 is energized to move its armature 187 downward. The ejector armature 187, in moving downward, strikes the holder 29 moved by the carrier 43 and forces the holder 29 into the recess 27 to terminate the printing cycle of the first microfilm 20.

Thereafter, the carrier 43 returns to the rack 28 to receive a second holder 29 with a second microfilm 20 to be printed. At this time, the switches 142 and 210 are set, either manually or by the automatic means referred to in conjunction with the copending application of Butterfield and Sulzer, Serial No. 186,008, filed September 21, 1950, now Patent No. 2,641,997, issued June 16, 1953, to the number of copies which it is desired to print. The cycle of operation for the printer and feeding means described above is then repeated until such time as the last holder 29 and microfilm 20 which it is desired to print have been ejected. At that time the dummy holder 29, containing no microfilm 20 drops into position on the carrier 43 and in doing so releases the switch 61 so that the spring 66 forces the switch 61 open to render the reciprocating drive 60 inoperative until another holder 29 and film 20 are again placed in the rack 28 for printing.

' It is to be understood that the above-described embodiment is simply illustrative of an application of the principles of the invention and numerous other embodiments may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In combination, a photoconductive printing surface, means for moving said printing surface, means for placing an electrostatic charge on the surface, a source of light energy, an optical system for projecting the light energy onto said charged surface to modify the charge thereon, and means for varying said light energy in synchronism with the movement of the printing surface, said light varying means comprising a plurality of holders for carrying objects to be printed, said holders each having two light transmitting portions therein, means for repetitively moving one of the holders through the light energy to produce variations therein in accordance with the object carried by the moving holder, light sensitive means, means for energizing the light sensitive means in response to the movement of the two light transmitting portions through the light energy to produce a first and a second electrical pulse, said first pulse producing a counting pulse and actuating the printing surface movmg means, said second pulse de-actuating the printing surface moving means, a counting circuit energized by said counting pulse for totalizing a series of such countmg pulses, and means energized by said counting circuit upon rece pt of a predetermined number of pulses for e ecting said moving holder whereby another of the pluralrty of holders may be moved into printing position.

2. In combination, a photoconductive printing surface, means for moving said printing surface, means for placing an electrostatic charge on the surface, a source of llght y. an optical system for projecting the light energy onto said charged surface to modify the charge thereon, and means for repetitively providing variations in said light energy in synchronism with the movements of the surface, said means comprisnig a plurality of holders for carrying objects to be printed, said holders each having two light transmitting portions therein, means for repetitively moving one of the holders through the light energy to produce light variations therein in accordance with the object carried by the moving holder, light sensitive means, means for energizing the light sensitive means in response to the movement of the two light transmitting portions through the light energy to produce a first and second electrical pulse, said first pulse producing a counting pulse and energizing the printing surface moving means, said second pulse de-energizing said printing surface moving means, a circuit connected to said light sensitive means for totalizing the counting pulses, means connected to said counting circuit for resetting said counting circuit to a zero pulse count after said circuit counts a predetermined number of pulses, and means acting simultaneously with said resetting means for replacing said moving holder with another of the plurality of holders whereby a second of the plurality of objects is produced as an electrostatic image on the printing surface.

3. An electrophotographic printer for reproducing an object comprising photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving the object past said light source, an optical system for applying said light source as varied by the obiect moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of the object moving past said light source, and ejecting means controlled by said photoelectric means responsive to the light for ejecting the object upon completion of a predetermined number of cycles of movement of the object.

4. An electrophotographic printer for reproducing an object comprising photoconductive printing means. means for moving said printing means, means for applying an uniform electrostatic charge to said printing means. a li ht source, cyclically moving means for moving the object past said light source. an optical system for applying said li ht source as varied by the obiect moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to li ht from said light source during each cyclic movement of the obiec't moving past said light source, ejecting means controlled by said photoelectric means res onsive to the light for ejecting the obiect upon completion of a predetermined number of cycles of m vement of the obiect, and means controlled by said photoelectric means for controlling movement of said printing means moving means. whereby said printing means will be moved only during the movement of the obiect past said light source.

5. An electrophotographic printer for reproducing an obiect comprising photoconductive printing means, means for applying an uniform electrostatic char e to said printing means, a li ht source. c clically moving means for moving the object past said light source. an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to li ht from said light source during each cyclic movement of the object moving past said li ht source, counting means controlled by said photoelectric means responsive to the li ht for counting the number of cycles of movement of the obiect, and e ecting means controlled bv said counting means for eiecting the obiect after a predetermined number of cyclic movements has been counted.

6. An electrophotographic printer for re roducing a plurality of obiects comprising hotoconductive printing means. means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the objects ast said light source. an o tical system for a plying said li ht source as varied by the ob ect moving therepast to said printing means to produce a li ht image thereon, photoelectric means respon'sive to light from said light source during each cyclic movement of the object moving past said light source, and means controlled by said photoelectric means responsive to the light for replacing the moving object with another of the plurality of objects after a predetermined number of cycles of movement of the moving ob ect.

7. kn electrpphotographic printer for reproducing a plurality of ob ects comprising photoconductive printing means, means for applying an unifionm electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the objects past said light source, an optical system for applying said light source as varied by said object moving therepast to said print ng means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of the object moving past said light source, means controlled'by said photoelectric means responsive to the light for replacing the moving ob ect with another of the plurality of objects after a predetermined number of cycles of movement of the moving ob ect, and means controlled by the replacement of the last of the objects to be reproduced for rendering said cyclically opcrating means inoperative.

'8. An electrophotographic printer for reproduc ng a plurality of objects comprising PhOlIOCOIIdUCtIVB PI'IIIt'mg means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the objects past said light source, an optical system for applying said light source as varied by the object moving therepast to said print ng means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of the object movmgpast said light source, counting means controlled by said photoelectric means responsive to the light for counting the number of cycles of movement of the object, and means controlled by said counting means for replacing the moving ob ect with another of the plurality of objects after a predetermined number of cycles of movement of the moving ob'ect.

9. An electrophotographic printer for reproducing a plurality of objects comprising photoconductive printing means, means, for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the plurality of objects past said light source, said means having control indicia there- On for passing light from said light source, an optical system for applying said light source as varied by the ob ect moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to the light passed by said indicia from said light source, counting means controlled by said photoelectric means for counting the number of cyclic movements of the object, and an ejector controlled by said counting means for ejecting the moving object upon completion of a predetermined number of cycles of movement of said cyclically moving means.

10. An electrophotographic printer for reproducing a plurality of objects comprising photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the objects past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of the object moving past said light source, counting means controlled by said photoelectric means responsive to the light for counting the number of cycles of movement of the object, means under the control of said counting means for ejecting the object from said cyclically moving means after a predetermined number of cycles of movement, and means forming a portion of said counting means for varying the predetermined number of cvcles at which said ejecting means will be operated.

11. An electrophotographic printer for reproducing a plurality of objects comprising photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of the objects past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of the object moving past said light source, counting means controlled by said photoelectric means responsive to the light for counting the number of cycles of movement of the object, means connected to said counting means for selectively predetermining the number of cycles of movement to be counted, means controlled by said counting means upon completion of the predetermined selection to return said a 14 counting means to its initial position, and ejecting means controlled by said counting means for ejecting the moving object upon completion of the predetermined selection of number of cycles of movement.

12. An electrophotographic printer for reproducing objects comprising a plurality of holders for carrying the objects to be reproduced, photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of said holders past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of said holder moving past said light source, means controlled by said photoelectric means responsive to the light for counting the number of movements of said holder, and means controlled by said counting means for ejecting said moving holder upon completion of a predetermined number of movements of said holder.

13. An electrophotographic printer for reproducing objects comprising a plurality of holders for carrying the objects to be reproduced, photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of said holders past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of said holder moving past said light source, means controlled by said photoelectric means responsive to the light for counting the number of movements of said holder, and means controlled by said counting means for replacing said moving holder with another of said plurality of holders upon completion of a predetermined number of movements of said holder.

14. An electrophotographic printer for reproducing objects comprising a plurality of holders for carrying the objects to be reproduced, photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of said holders past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of said holder moving past said light source, means controlled by said photoelectric means responsive to the light for counting the number of movements of said holder, means controlled by said counting means for replacing said moving holder with another of said plurality of holders upon completion of a predetermined number of movements of said holder, and means controlled by said counting means for rendering said cyclically moving means inoperative upon completion of a predetermined number of cycles of movement of the last of said holders.

15. An electrophotographic printer for reproducing objects comprising a plurality of holders for carrying the objects to be reproduced, photoconductive printing means, means for applying an uniform electrostatic charge to said printing means, a light source, cyclically moving means for moving one of said holders past said light source, an optical system for applying said light source as varied by the object moving therepast to said printing means to produce a light image thereon, photoelectric means responsive to light from said light source during each cyclic movement of said holder moving past said light source, means controlled by said photoelectric means responsive to the light for counting the number of movements of said holder, means controlled by said counting means for replacing said moving holder with another of said plurality of holders upon completion of a predetermined number of movements of said holder, and means forming a portion of said counting means for varying the predetermined number of movements at which said replacing means will be operated.

(Other references on following page) 15 1:6 UNITEDSTATES PATENTS 23 ,304 gorelsnsen lskug. 31, 192

2, ,809 arson ept. 12, 19 $53 323 gnyder 5%; 2,406,040 Ryan et a1. Aug. 20, 1946 2,221,776 f 8 1940 2,600,470 Breuers et a1. June 17, 1952 ar I 5 2,609,680 Caldwell Sept. 9, 1952 2,228,820 Griffith Ian. 14, 1941

Claims

1. IN COMBINATION, A PHOTOCONDUCTIVE PRINTING SURFACE, MEANS FOR MOVING SAID PRINTING SURFACE, MEANS FOR PLACING AN ELECTROSTATIC CHARGE ON THE SURFACE, A SOURCE OF LIGHT ENERGY, AN OPTICAL SYSTEM FOR PROJECTING THE LIGHT ENERGY ONTO SAID CHARGED SURFACE TO MOFIFY THE CHARGE THEREON, AND MEANS FOR VARYING SAID LIGHT ENERGY IN SYNCHRONISM WITH THE MOVEMENT OF THE PRINTING SURFACE, SAID LIGHT VARYING MEANS COMPRISING A PLURALITY OF HOLDERS FOR CARRYING OBJECTION TO BE PRINTED, SAID HOLDERS EACH HAVING TWO LIGHT TRANSMITTING PORTIONS THEREIN, MEANS FOR REPETIVELY MOVING ONE OF THE HOLDERS THROUGH THE LIGHT ENERGY TO PRODUCE VARIATIONS THEREIN UN ACCORDANCE WITH THE OBJECT CARRIED BY TE MOVING HOLDER, LIGHT SENSITIVE MEANS, MEANS FOR ENERGIZING THE LIGHT SENSITIVE MEANS THE RESPONSE TO THE MOVEMENT OF THE TWO LIGHT TRANSMITTING PORTIONS THROUGH THE LIGHT ENERGY TO PRODUCE A FIRST AND A SECOND ELECTRICAL PULSE, SAID FIRST PULS PRODUCTING A COUNTING PLUS AND ACTUATING THE PRINTING SURFACE, MOVING MEANS, SAID PLUS DE-ACTUATING THE PRINTING SURFACE MOVING MEANS, A COUNTING CIRCUIT ENERGIZED BY