JPH05286609A - Sheet feeding apparatus - Google Patents

Abstract

PURPOSE: To perform lateral registering of a sheet at a low cost and with accuracy and reliability when the sheet is stopped and inverted, related to a both-side copier or printer. CONSTITUTION: A sheet feeding apparatus comprises a feed roller 41, etc., for feeding a sheet 50, and members 52 and 53 for aligning sheets in the direction across a process direction. The aligning member comprises a member 53 for laterally shifting a carriage 52 provided with the feed roller. A sensor 57 for a sheet is provided, for controlling a lateral shift member according to the signal. If the sheet 50 is not detected, the lateral shift member acts to move a feed member laterally toward the sensor, then the lateral movement is stopped when the sheet is detected with the sensor. If the sheet is detected, firstly the lateral shift member is operated to laterally move the feed member away from the sensor, and when no sheet is detected, the lateral shift member is operated to move the feed member toward the sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus useful in a copying machine or printer such as an electrostatographic copying machine or an electrostatographic printer. In copiers and printers, it is necessary to align the copy sheets both in the process direction and transverse to the process direction to ensure the correct position of the image on each sheet. The present invention relates to lateral alignment of sheets in a sheet feeder.

[0002]

Devices for lateral shifting and alignment of sheets are known and are described, for example, in U.S. Pat. No. 4,712.
There are lateral seat shift or offset mechanisms of U.S. Pat. No. 786 and U.S. Pat. No. 4,480,825.
U.S. Pat. No. 4,712,786 discloses a printer device including a sorter and an offset device. The offset device is located in the printer and moves the sheets back and forth with respect to the sorter, so that the sheets are offset before entering the sorter and subsequent sheet sets are offset from each other in the sorter pockets. An apparatus for separating a set of copy sheets from a copier is disclosed in U.S. Pat. No. 4,480,825, which feeds a set of sheets alternately along a plurality of vertically overlapping and laterally separated overlapping passages. Includes a feed mechanism to a stationary tray for feeding. Sheets are first fed through a laterally fixed device of the opposing feed rollers and then enter the stacker through a second laterally movable device of the feed rollers. Sheets belonging to the alternating sets are offset by laterally shifting the second set of rollers.

US Pat. No. 4,823,159 discloses a lateral shift and alignment arrangement in which a sheet is fed between two cooperating nip rollers and when the sheet is in the nip between the nip rollers. The nip roller is then stopped and laterally shifted, after which the edge of the sheet is detected by the sensor. The sheets are then aligned transversely or transversely to the process direction and fed to the next step in the process by rotation of the rollers. In this way, the sheets can be laterally aligned when held in the nip between the rollers. After each sheet has been ejected from the rollers, the roller arrangement is shifted in the opposite lateral direction in the alignment direction,
In other words, it returns to the “home” position.

The arrangement described in US Pat. No. 4,823,159 is particularly useful in copiers that perform double-sided copying, in which the copy sheet bearing the image on the first side is stopped and then in the opposite direction. To receive the image on the second surface. Before feeding in the opposite direction, the sheets must be realigned laterally of the process direction. Another device for realigning copy sheets in a similar situation is described in EP-A-0,378,005, here the first
Sheets that have passed through the sheet configuration in the process direction are not laterally shifted, but are laterally shifted when stopped and inverted so that the sheet is driven toward the end registration wall.

[0005]

However, in particular, as described above, in a copying machine or printer for double-sided copying, a device for laterally aligning a sheet when the sheet is stopped and inverted is much cheaper. Need accurate, high reliability.

[0006]

SUMMARY OF THE INVENTION In view of the above need, the present invention therefore provides, according to the present invention, a feeding means for feeding sheets in the process direction and aligning the sheets transverse to the process direction. The aligning means for shifting the feeding means in the lateral direction, the sensor arranged to detect the presence of the sheet and generate a signal, and the aligning means in response to the signal. A sheet feeding device comprising a control means for controlling a shift means, wherein the control means shifts the sheet when the sheet is not detected by the sensor at the first input of the sheet to the feeding means. Means operate to move the feeding means laterally toward the sensor and then stop the lateral movement when the sheet is detected by the sensor, or the feeding means What When a sheet is detected at the time of the first input of the sheet, first, the shift means is operated to move the feeding means laterally away from the sensor, and then the sheet is detected by the sensor. If not, the sheet feeding device is provided, wherein the shift means is operated to move the feeding means toward the sensor.

Preferably, the sheet feeding apparatus drives the feeding means to drive the sheet in the first direction, stops the sheet in the feeding means, and aligns the sheet by the aligning means,
Includes means for reversing the feeding means and driving the sheet in a direction opposite to the first direction. The feeding means may comprise at least one pair of rollers mounted on the carriage and the lateral shift means are connected to the carriage.

[0008]

According to the sheet feeding apparatus of the present invention, a wide range of sheet positions when the sheet enters the apparatus can be accommodated on either side of the desired alignment position. Whatever the initial sheet position, the sheet feeder of the present invention is always aligned in the same direction, which results in backlash in the system.
h) Or the mismatch due to hysteresis can be eliminated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the essential portions of an electrostatographic laser printer 10 are shown. This printer produces a print or copy of input information in electronic form derived from a document. Digital input information in electronic form is processed by an electronic subsystem (ESS) 11 and used in a raster output scanner (ROS) 13 to modulate a scanning light beam 12 generated by a laser. The light beam 12, typically a laser beam, is directed onto a photoreceptor contained within an electrostatographic cassette 14. The photoconductor is uniformly electrostatically charged and moves so as to pass through the lower slit of the cassette 14. The light beam 12 is scanned across the slit to form an electrostatic latent image on the photoreceptor by selectively discharging a uniform charge by imagewise exposure.
The electrostatic latent image is developed with toner particles that selectively adhere to the latent image of the same shape as the image, and the developed image is transferred to a paper sheet at transfer station 15. afterwards,
The paper sheet with the developed image passes through a fuser 16 which comprises a heating roller and a cooperating backup roller to fuse the image to the paper sheet to form a permanent print or copy. The copy is then transported into one of the two output trays described below or, if in duplex mode, returned to the electrostatographic cassette,
The second surface receives another developed image.

The paper sheet for receiving the developed image is removed from any one of the four trays 21, 22, 23, 24, these different trays having different sizes,
It is designed to include different numbers of seats. For example, the tray 21 is a large-capacity tray containing size sheets most frequently used in the printer, for example, A4 size sheets. The trays 22 and 23 accommodate larger sizes, and the tray 24 can be used to contain specialty paper such as color sheets, transparencies, and the like. Sheet is tray 2
1, 22, 23, 24 by the corresponding sheet feeders 31, 32, 33, 34 respectively, and thereafter
Sheets taken out by the transport rollers via the convergent sheet path and finally from any of the four trays are also fed by the common feed roller pair 25 to the electrostatographic cassette 14 at the transport station 15. .. After that, the sheet having the developed image is fixed to the fixing device 1.
Pass 6.

The next processing of the copy sheet by the machine depends on whether single-sided or double-sided copying is done. If a one-sided copy is to be made, the sheet passes through the transport rollers 27 and 28, and then moves to the upper paper path 26. Thereafter, the sheet rotates above the sheet passage 30 and enters the upper output tray 35. Alternatively, it proceeds in a substantially horizontal direction along the passage 36 to the reversing drum 37 and then into the receiving tray of the high capacity stacker 38. A suitable seat deflector is provided at position 29 to seat the seat in the seat passage 3
Pass a selected one of 0, 36.

When a two-sided copy is made, the sheet with the first side image passes through the transport rollers 27, 28,
At the position 39, it is turned and goes along the lower sheet path 40 toward the reversing roller pair 41, 42. After the main part of the sheet has been fed into the sheet path 43 by the reversing rollers 41, 42 and, if necessary, into the vertical storage pocket 44, the reversing rollers 41, 42 stop and reverse,
As a result, the sheet is re-fed along the return paper path 45,
The sheet passes between the transport rollers 28 and 46, and merges with the sheet path where the sheet fed from the uppermost tray 24 from the beginning normally passes. The sheet then receives the developed image on the other side at the transfer station 15 of the electrostatographic cassette 14 through the common feed roller 25. After that, the double-sided copy passes through the above-mentioned upper surface paper path 26, and is selected and fed between sheet output to the upper surface output tray 35 and sheet output to the high capacity stacker 38.

Referring to FIG. 2, there is shown a reversing roller 41 (the lower roller 42 cooperating therewith is not shown). The rollers 41 or 42 are driven so that they cooperate to drive the sheet 50 in the direction of arrow 51 until the main part of the sheet has passed between the rollers. The rollers are then stopped and the sheets are laterally aligned, as described below. The rollers are then inverted to return the sheet to the electrostatographic cassette as described above.

The lateral alignment of the sheets is achieved by the movement of a carriage 52 having rollers 41, 42, which is driven by a motor 53 laterally in the process direction. Before each sheet of paper is fed to the rollers 41, 42, the carriage is brought to the "home" position by the motor 53, which home position is detected by the home position sensor 54. In this case, the carriage 52 moves to the right when the home position sensor 54 confirms the carriage 52 during the feeding of consecutive sheets, and moves to the left when the home position sensor 54 cannot confirm the carriage 52. .. When the state of the home position sensor 54 changes, the motor 53 is stopped and
The carriage 52 will be located at its home position. The paper sheet then enters rollers 41, 42,
A wide range of lateral positions can be taken, indicated by the extreme positions shown by the dotted lines 55,56. When the sheet enters the correct range through the reversing rollers 41 and 42, the rollers 41 and 42 stop. At this time, when the sheet edge sensor 57 cannot confirm the sheet, the motor 53 drives to move the carriage, and thus the roller having the sheet moves to the left side. Seat edge sensor 5
When state 7 changes, motor 53 is stopped and the sheets are aligned. However, when the sheet edge sensor 57 can confirm the sheet, the motor 53 is driven,
The carriage 52 is moved to the right until the sheet end sensor 57 cannot confirm the sheet. When the sheet cannot be confirmed, the motor 53 is reversed and the carriage 52
Moves to the left. When the state of the sheet edge sensor 57 changes, the motor 53 stops and the sheets are aligned.

Thus, the rattling (b
ACKlash) or hysteresis in the sheet edge sensor is taken into account. Once the sheets are aligned, they are easily returned to the transfer station.

[0016]

The aligning device of the present invention is accurate and reliable in the above-described reversing roller arrangement or in other cases where the sheets need to be aligned laterally of their processing direction. Low cost sheet alignment is possible. The approaching sheet can be located over a large lateral position range so that the edge of the sheet may or may not be initially detected by the sheet edge sensor. This configuration is very economical for space within the machine.

[Brief description of drawings]

FIG. 1 is a schematic view showing a paper path in a printer capable of double-sided copying and incorporating a sheet feeding device of the present invention.

FIG. 2 is a plan view of the sheet feeding device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Laser printer 11 ... Electronic subsystem (ESS) 12 ... Scanning light beam 13 ... Raster output scanner 14 ... Cassette 15 ... Transfer station 16 ... Fixing device 21, 22, 23, 24 ... Feed tray 25 ... Feed roller Pair 26 ... Top paper passage 27, 28 ... Transport roller 30 ... Sheet passage 31, 32, 33, 34 ... Sheet feeding device 35 ... Top output tray 38 ... High-capacity stacker 41, 42 ... Reversing roller 45 ... Return paper passage 46 ... transport roller 52 ... carriage 53 ... motor 54 ... home position sensor 57 ... sheet end sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03G 15/00 106 110 7369-2H (72) Inventor Paul Sheerbold England Berkshire Sheddington Pittstone Marsworth Road 31

Claims (1)

[Claims] 1. A feed means for feeding a sheet in a process direction and an aligning means for aligning the sheet in a direction transverse to the process direction, wherein the aligning means shifts the feed means laterally. In the sheet feeding device, a sheet feeding device including a unit, a sensor provided to generate a signal by detecting the presence of a sheet, and a control unit that controls the shift unit according to the signal, When a sheet is not detected by the sensor at the first input of the sheet to the feeding means, the shift means operates to move the feeding means laterally toward the sensor, and then: When the sheet is detected by the sensor, the lateral movement is stopped, or when the sheet is detected when the sheet is first input to the feeding means, first, the shift Means to move the feeding means laterally away from the sensor, and then when the sheet is no longer detected by the sensor, the shift means is operated to move the feeding means to the sensor. A sheet feeding device, characterized in that it is adapted to move toward.