US3545742A

US3545742A - Automatic paper feeder

Info

Publication number: US3545742A
Application number: US744583A
Authority: US
Inventors: Alex M Muller; Kunio A Sumida
Original assignee: Telautograph Corp
Current assignee: Telautograph Corp
Priority date: 1968-07-12
Filing date: 1968-07-12
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08
Also published as: SE356866B; GB1247773A; FR2016796A1; DE1935425A1

Description

United States Patent Inventors Alex M. Muller Redondo Beach, California; Kunio A. Sumida, Los Angeles, Calif. Appl. No. 744,583 Filed July 12,1968 Patented Dec. 8, 1970 Assignee Telautograph Corporation Los Angeles, California a corporation of California AUTOMATIC PAPER FEEDER 9 Claims, 5 Drawing Figs.

US. Cl 271/10, 271/57 Int. Cl B65h 5/06, B65h 7/18 Field ofSearch 271/10, 36,

[56] References Cited UNITED STATES PATENTS 2,759,729 8/1956 Hedlun............;......... 271/10 3,339,917 9/1967 Petrovsky 271/36 Primary Examiner Edward A. Sroka Attorney Lindenberg & F reilich ABSTRACT: Apparatus for feeding individual sheets of paper from a stack through a facsimile transmitter with a minimum spacing between succeeding sheets. The apparatus comprises a feed roller which rapidly moves a sheet from the stack along a feed path to a slow moving belt, and a paper sensing switch which stops rotation of the feed roller as soon as the leading i edge of the sheet reaches the belt. When the trailing edge of the sheet leaves the position of the paper sensing switch, the feed roller is again driven to remove another sheet and send it rapidly to the belt.

AUTOMATIC PAPER-FEEDER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to paper feeding mechanisms.

2. Description of the Prior Art One type of facsimile transmitter accepts a stack of paper with images thereon and feeds the sheets of paper one at a time into a scanner. The scanner scans the sheet, one line at a time, and transmits the images to a distant receiver. In order to provide reliable automatic operation, the paper feeder must deliver only one sheet at a time, leaving at least a small gap between succeeding sheetsJForefticient utilization of the apparatus, the gap between sheets must be very small.

One prior art feed apparatus utilizes a feed roller which moves one sheet at a time from a'stack holder to a belt. The belt engages the sheet and carries it at a slowspeed, such as 6 inches perminute, past an optical scanner. The feed roller turns continuously to remove one sheet after another from the stack. However, the roller turns at a-slightly slower speed than the belt in order to leave a small gap between the trailing edge of one sheet and the leading edge of the next sheet. The feed rollers become worn and may slip on the paper so that a large gap is left between sheets. This results in the user paying for the high transmission costs while no image is being transmitted. In addition, the feed rollers often skew the paper, and following sheets tend to acquire the same skew so that information on edge portions of the sheet may not be transmitted.

OBJECTS AND SUMMARY OF THE INVENTION One object of the present invention is to provide a slow rate feeding mechanism which.limits skew and which assures a small but controlled gap between successive sheets.

Another object is to provide apparatus for the more positive control of paper feeding] i In accordance with the present invention, a mechanism is provided for positive control of paper feeding, to reduce skew and to reduce the gap between succeeding'sheets of paper. Such feed mechanisms find particular use in a facsimile transmitter wherein the paper is moved slowly past a scanner. The sheet feeding mechanism comprises a slow sheet transport for final handling of thesheet and a fast sheet transport for moving individual sheets from a stack to the slow sheet transport. A sheet sensing switch is located near the point where sheets are transferred from the fast transport to the slow transport.

point of transfer betweenthe fast and slow transports, means are provided for abutting the leading edge of the sheet to stop it.

The gap between sheets is held to a small and constant lengthby reason of the fact 'that the fast transport is energized only when the prior sheet has passed the sensing switch location. Even if minor slippage occurs in the fast transport, this does not unduly increase the gap between sheets, since the fast transport is energized untilthe paper reaches the slow transport. A t-the end of the fast transport path, when the sheet is decelerated, any large. skew is eliminated by reason of the stopping of the leading edge of the paper so that it lies parallel I to the path. I

transmitter where sheet scanning occurs.

In this embodiment of the invention, the slow transport comprises a belt which is driven slowly and a delivery roller which holds paper against the beltfThe sensing switch includes a pair of electrical contacts located near the nipformed by the belt and delivery roller. These contacts are separated when a sheet of paper is moved to the nip. When no paper is present at the nip, the feed roller motor is energized to rapidly move a sheet of paper until its leading edge is engaged between the belt and delivery roller. This opens the sensing switch and stops the energization of the feed roller. When the slow belt drive has moved the sheet far enough that its trailing edge passes the switch, the switch is gain closed to again energize the feed roller motor.

Each new sheet of paper removed from the stack moves rapidly until its leading edge strikes the nip between the belt and delivery roller. Any large skew in the sheet is reduced by reason of the abutting of theleading edge at opposite sides of its center. If the sheet is skewed, the trailing side of the sheet continues to move forward while the leading side'is stopped, thereby realigning the sheet. l v

The novel features of the invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 4 is a side elevation view taken on the line'4-4 of FIG.

3; and i FIG. 5 is a diagram of a control circuit used with the a' paratus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a portion of a facsimile transmitter comprising a frame 11 with a hopper 10 for receiving a stack of sheets of paper.v Each of the sheets carries an image, which may be a printed or written message, a photograph, or other information. The sheets are fed one at a time along a path past a scanning aperture 12. An electric lamp 14 projects a beam of light that is reflected and concentrated by a mirror 16 at the scanning aperture. A system including a lens 18, mirror 20, and a mechanical light chopper (not shown) scans the image lying within the scanning aperture 12. Electrical circuitry (not shown) converts the dissected optical image'into electrical signals for transmission over telephone lines or the like to a distant receiver, where the image is reconstructed.

In order to transmit the information on the entire stack of sheets in the hopper 10, the sheets must be moved one at a time along the path past the scanning aperture 12. The facsimile transmitter is often used for transmission over long distances, such as across the country, and the charges for use of telephone cables is relatively high. Accordingly, it is desirable to provide as small a gap as possible between the trailing edge of one sheet and the leading edge of the next, so that transmission time is not wasted by scanning long gaps. On the other hand, it is important to make sure that only one sheet at a time is moved past the scanning aperture, so that all of the information on a sheet is transmitted. In addition to providing a small gap between sheets, the paper feeding apparatus must 7 prevent the introduction of large skew. This is because the width of the scanning aperture 12is generally adjusted to the width of the paper placed in the hopper 10, to eliminate scanning on either side of the paper. If the paper is skewed,

some portions on either side of the paper will not be scanned,

and the complete imageswill not be transmitted.

The paper feeding mechanism comprises a slow transport means which moves each sheet of paper slowly past the scanning aperture 12. The slow transport 22 comprises a rubber belt 24 which extends between a drive wheel 26 and an idler wheel 28. The drive wheel 26 moves at a slow speed, such as a peripheral speed of one-tenth inch per second, thereby moving the belt past the scanning aperture 12 at the same slow speed. A delivery roller 30 and pressure roller 32 lie on opposite sides of the belt, both being idler rollers. The delivery roller 30 has a shaft 34 which is fixed in place on the frame 11. The pressure roller 32 is rotatably mounted at the end of an arm 36 that pivots about a point 38, the arm being spring biased upwardly toward the delivery roller. Each sheet of image-bearing paper is initially received between the delivery roller 30 and belt 24. The pressure roller 32 deflects downwardly sufficiently to enable receipt of the leading edge of the paper. The pressure roller then applies the pressure necessary to assure firm engagement of the paper between the delivery roller and belt.

The movement of paper from the hopper to the slow transport 22 is accomplished by a fast transport means 40 which comprises a pair of feed rollers 42 mounted on a feed roller shaft 44. A reverse roller 46 mounted on a reverse roller shaft 48 is disposed on a side of the hopper opposite the feed roller 42. The hopper 10 is tapered to a narrow throat S0, and the feed roller and reverse roller have peripheral portions extending through openings in the hopper walls immediately above the throat. A stack 52 of sheets of paper with images thereon to be transmitted is laid in the hopper 10 in an almost vertical position. A bar 53 mounted on the frame lies against the forward face of the stack 52 to prevent the paper from falling over. A pair of paper-centering brackets 47, which are moved together and apart by a manually turned lead screw 49, keeps the stack of sheets atthe center of the fast transport path.

The feed roller shaft 44 is coupled by a chain belt to the output shaft 56 of a feed motor 54. initially, the feed motor 54 is energized and rotates the feed roller 42 at a rapid rate such as several revolutions per second. The feed roller engages the sheet shown at 55 at the bottom or back of the stack and moves it downwardly along an initial path defined by a guide plate 58. The sheet continues to move along this path until it reaches the forward nip between the delivery roller 30 and the belt 24. The leading edge of the sheet 55 deflects the belt 24 and pressure roller 32 thereunder downwardly a small amount sufficient for the leading edge to be engaged between the roller 30 and belt, as shown in FIG. 2.

As the leading edge of the sheet approaches the forward nip at the delivery roller, it raises a contact 60 of a paper sensing switch 62. The raising of contact 60 breaks an electrical circuit between the contact 60 and another contact 64 below the paper. The opening of the sensing switch 62 results in the deenergization of the motor 54 and the application ofa motor brake (not shown) thereto for a brief time. This quickly stops the rotation of the feed roller 42 so that it no longer feeds paper toward the belt, and the feed roller is then freewheeling.

The sheet 55 is now engaged between the delivery roller 30,

located at the down-path end of the initial path, and the belt 24. The sheet then moves along another path defined by the belt, toward the scanning aperture 12 at a slow rate, such as one-tenth inch per second. As it passes the scanning aperture, the images thereon are optically scanned for transmission. The sheet of paper continues to move along the belt until it is deposited in an after hopper 66.

When the trailing edge of the sheet passes the paper sensing switch 62, the contact 60 again falls on the other contact 64. This again energizes the feed motor 54 to drive the feed roller 42, so that the next sheet of paper is drawn out of the stack 52 and is moved rapidly along the guide plate 58 to the nip of the delivery roller 30. The inertia of the feed motor 54 and feed rollers, and their speed ofoperation, is chosen so that the leading edge of the next sheet reaches the nip ofthe delivery roller 30 at a time when a trailing edge of the preceding sheet has just passed the nip. This leaves a gap between sheets, which is chosen to be a small distance such as one-eighth inch. The motor 54 accelerates the feed roller rapidly, which shakes up" the stack of sheetsin the hopper and jerks the bottom sheet away from the others. It is found that this tends to separate the sheets and substantially reduces the chance that more than one sheet will be fed.

The feed rollers 42 are constructed of a soft rubber having a high coefficient of friction with respect to paper. This coefficient of friction is higher than the coefficient of friction of paper on paper or of the reverse roller 46 on paper. As a result, a sheet of paper in contact with the rotating feed roller 42 is driven along the path towards the belt, instead of being held back by another piece ofpaper or by the reverse roller; 46 which is engaged with the other face of the sheet. Some slippage of the feed roller on the paper may occur, but it rarely lasts for more than a fraction of a revolution of the feed roller. Such slippage does not substantially affect the gap between successive sheets at the scanning aperture 12 because the preceding sheet moves past the scanning aperture only a small fraction of an inch during even a complete revolution of the feed roller. The advantage of continuous rotation of the feed roller until a sheetis sensed near the nip of the delivery roller can be appreciated by comparison with previous feed mechanisms wherein the gap between successive sheets increased by approximately the total amount of any slippage.

The reverse roller 46 is preferably constructed of a material with a lower coefficient of friction on paper than the feed roller 42 on paper, but with a coefficient greater than that between two sheets of paper. The reverse roller may be constructed of a medium-hard rubber or of relatively soft plastic. The reverse roller shaft 48 is turned in the direction indicated by arrow 49 during the entire time that the machine is operating to scan the sheets. As a result, the reverse roller tends to move any sheet of paper which passes by it, back into the hopper 10. In some instances, two or more sheets may pass between the feed and reverse rollers and through the throat 50 towards the belt. The extra sheets rarely move all the way to the nip, but they may move part of the way. The reverse roller 46 turns slowly, having a peripheral speed approximately onehalf the belt speed, so that the extra paper is gradually moved back into the hopper. This helps to prevent jamming of the feed apparatus. The reverse roller does not move back a sheet which has reached the nip of the delivery roller 30, because such a sheet is firmly engaged between the delivery roller and the belt.

When a sheet from the stack 52 is accelerated by the feed roller toward the belt, some skew may be imparted. This may occur, for example, if one feed roller slips while the other does not, or if one feed roller slips more than the other, Such skew is generally eliminated when the sheet strikes the nip of the delivery roller 30. This is because the delivery roller 30 extends across substantially the entire width of a sheet, except for a center portion of the roller which is of reduced diameter. The reduced diameter portion is provided to accommodate the sensing switch contact 60 immediately up-path from the nip of the delivery roller. If a sheet is skewed, its leading edge is not parallel to the length of the nip of the delivery roller. As a result, one side of the leading edge reaches the nip first, and when it hits the belt or delivery roller at the nip, the sheet is buckled on the leading side, which causes the reduction of skew.

The facsimile machine is generally left constantly in a standby condition, so that all of the apparatus is kept heated to operating temperature. During standby operation, however, the lamp 14, a copy motor 72 which drives the drive wheel 26, and reverse roller 46 and feed motor 54 are deenergized. The apparatus may be started by inserting a first sheet through a manual feed opening 70 to the nip of the delivery roller 30. The first sheet opens the paper sensing switch 62, which causes the apparatus to be placed in an operating state. While the machine is in the operating state, the lamp l4 and copy motor 72 are on continuously, while the feed motor 54 is turned on whenever the sensing switch 62 is closed. The copy motor 72 drives a transmission chain 73 that rotates the belt drive wheel 26 and the reverse roller shaft 48.

The first sheet moves along the belt until its trailing edge has passed the contact 60. At this't'ime, the feed motor 54 rotates the feed roller 42 to feed the next sheet to the belt. When a trailing edge of the last sheet in the stack 52 passes the contact 60, the feed motor 54 is turned on and the feed roller 42 starts to spin. After a predetermined period such as a few seconds, the machine is placed in a standby, or nonoperating state, wherein the lamp l4 and the

motors

54 and 72 are deenergized. This provides for automatic stopping of the transmission when the last sheet in the stack is transmitted, and also provides for stopping if: amalfunction occurs which prevents feeding to the belt. In order to start the machine again, another sheet may be manually fed through the slot 70. Alternatively, all of the sheets may be placed in the stack 52, and a pushbutton depressed for placing the apparatus in the operating state to start the feeding of the first sheet.

FIG. 5 is a diagram of acircuit which automatically places the paper feed apparatus in an operating or nonoperating condition, and controls the energization of the feed motor. The circuit comprises a pair of

electrical conductors

80 and 82 for coupling it to a power source indicated at 84, which may be an ordinary electrical outlet. A circuit between the power source and the copy motor 72 can be completed by an operating switch 86. The circuit between the feed motor 54 and the power source can be completed by closing of both the operating switch 86 and the paper sensing switch 62. A timer 88 monitors the state of the paper sensing switch 62 and controls a relay coil 90 which opens and closes the operating switch 86. If the timer 88 senses that the paper sensing switch 62 is closed for more than a predetermined period, such as several seconds, it operates the coil 90 to open the operating switch 86. So long as the sensing switch 62 is opened, or is closed no more than several seconds, the operating switch 86 remains continuously closed. A pushbutton 92 is provided which is in parallel with the operating switch 86, to enable bypassing of the operating switch, for initially turning on the apparatus.

If the paper feed apparatus is in a nonoperating state, it can be placed in an operating state in either of two ways. One way is by manually feeding. a sheet of paper to the nip of the delivery roller, thereby opening the paper sensing switch 62. Upon opening the switch 62, the timer 88 energizes the coil 90 to close the operating switch 86. The copy motor '72 is then energized, so that the belt which moves paper past the scanning aperture begins to turn. when the trailing edge of the first sheet passes by the sensing'switch 62, the sensing switch closes and turns on the feed motor 54. If at least one other sheet is in the stack 52, the sheet will be quickly fed to the belt, and the sensing switch 62 will again be opened.

Another way of initially placing the apparatus in an operating state is by merely loading a stack of sheets in the hopper and then depressing the pushbutton switch 92. When the pushbutton is depressed, current can flow to the feed motor 54, enabling the first sheet to be fed to the belt. The first sheet opens the sensing switch 62,. so that the apparatus can continue to operate. When the trailing edge of the last sheet has passed the sensing switch 6 2 the switch 62 remains closed while the feed motor 54 rotates. After a few seconds,- the timer 88 deenergizes the coil 90 to open the operating switch 86. The apparatus is then placed in a nonoperating state.

While the paper feeding apparatus of the invention is useful in facsimile transmitters, itis also useful in a variety of other applications. The use of a fast transport to move paper to a mechanism which thereafter moves it at a slower speed, and the use of a sheet sensor at the end of the fast transport, assures a small gap between sheets. The use of means that abut opposite sides-of the sheet to suddenly slow it, particularly where the sheet is substantially stopped as where it is slowed to less than an inch per second after traveling at least several inches per second, enables the substantial reduction of skew.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

We claim: 1. Apparatus for feeding individual sheets from a stack comprising:

fast transport means activatable to move individual sheets from said stack along a first path at a first speed;

slow transport means disposed to receive individual sheets from said first path, for substantially continually moving I said sheets along a second path at a second speed which is less than said first speed, said slow transport means spaced from said fast transport means a distance less than the length of said sheets;

sheet sensing means for detecting the presence of a sheet at an area near the intersection of said first and second paths; and

means responsive to said sheet sensing means for terminat ing activation of said fast transport means when said sheet sensing means detects a sheet. i l

2. Apparatus for feeding individual sheets from a stack comprising:

fast transport means for moving individual sheets from said stack along a first path at a first speed of at least several inches per second;

slow transport means disposed to receive individual sheets from said first path, for moving said sheets along a second path at a second speed which is less than an inch per second, said slow transport means including means for initially abutting sheets received from said first transport means at positions disposed on opposite sides of the center of said first path and disposed along a line substantially perpendicular to said paths to reduce large skew; and

sheet sensing means responsive to the presence of a sheet at an area near the intersection of said first and second paths for deactivating said fast transport means.

3. Apparatus for feeding individual sheets from a stack comprising:

fast transport means for moving individual sheets from said stack along a first path at a first speed;

slow transport means disposed to receive individual sheets from said first path, for moving said sheets along a second path at a second speed whichis less than said first speed, said slow transport means including a delivery roller disposed on one side of said second path and means disposed opposite said'delivery roller having a surface for continually moving along said second path to carry sheets therealong; and

sheet sensing means responsive to the presence of a sheet at an area near the intersection of said first and second paths for deactivating said fast transport means, said sheet sensing means including a pair of contacts disposed immediately up-path from the nip formed by said delivery roller and said means disposed opposite said delivery roller.

4. Apparatus for feeding individual sheets from a stack comprising: r

' fast transport means activatable to move individual sheets from said stack along a first path at a first speed;

slow transport means .disposed to receive individual sheets from said first path, for moving said sheets along a second path at a second speed which is less than said first speed;

sheet sensing means responsive to the presence of a sheet at an area near the intersection of said first and second path for deactivating said fast transport means; and

means for deactivating said fast transport means after a predetermined period of continual activation greater than the usual time between the activation of said fast transport means and the arrival of a sheet near the intersection of said first and second paths.

5. Apparatus for feeding paper through a facsimile transmitter comprising:

hopper means for holding a plurality of sheets;

means for carrying sheets at a constant slow speed along a scanning path;

means defining-an initial path between said hopper means and said means for carrying sheets at a slow speed;

feed roller means activatable to move individual sheets along said initial path at a fast speed which is substantially greater than said slow speed;

delivery roller means engageable with said means for carrying sheets at a constant slow speed, for holding sheets thereto, said delivery roller means disposed at the downpath end of said initial path;

means for sensing the presence of a sheet at a position near said delivery roller means; and

means responsive to said means for sensing, for activating said feed roller means until a sheet is sensed.

6. The apparatus defined in claim wherein:

said means for carrying sheets at a slow speed comprises a belt; and

said delivery roller means comprises a roller having portions on opposite sides of the center of said scanning path for engaging said belt, and means for biasing said belt and said delivery roller means toward each other to abut the leading edge of sheets moved down said initial path, whereby to reduce large skew.

7. The apparatus defined in claim 5 wherein:

means for rotating saidfeed roller; and including means for rotating said reverse roller, during periods when said feed roller is stationary, in a direction to move sheets back towards said hopper means, whereby to return the second sheet toward the hopper in case of double feeding. 9. Apparatus as defined in claim 5 including: means responsive to said means for sensing, for placing said facsimile transmitter in a nonoperating state to cease the transmittal of images, upon the absence of sensing of a sheet for a predetermined period.