JPH0577996A - Paper refeeder for sheet recorder - Google Patents

Abstract

PURPOSE:To miniaturize a device and further to attain a sure refeeding of paper by reducing a cost of the device and also increasing its longevity. CONSTITUTION:A weight 37 is mounted through an arm 36 to the turning center shaft 34 of a switching pawl 35 to give a turning habit by gravitational force to the switching pawl 35. A photointerrupter 38 for reversing a switchback roller 39 by detecting a turning position of the switching pawl 35 is provided. The switching pawl 35 is placed in the first position against gravitational force by a sheet having finished one side recording to feed the sheet into a switchback part 26, and after the rear end of the sheet passes, the switching pawl 35 is switched to the second position by the turning habit to detect the switching pawl 35 placed in the second position by the photointerrupter 38 and to reverse the switchback roller 39. The sheet is guided and switched back by the switching pawl 35 and refed to a printer main unit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printers, copying machines,
The present invention can be applied to a sheet recording device such as a facsimile machine or a printing machine, which records on a sheet by printing, transferring, copying, or printing. More specifically, in such a sheet recording apparatus, the switching claw is set to the first position to send the one-side recorded sheet to the switchback section, and then the switching claw is switched to the second position, and the switchback section is also set. The switchback roller is reversely rotated to switch back the sheet, and the sheet is fed again by being guided by the switching claw.

[0002]

2. Description of the Related Art Conventionally, this type of sheet re-feeding device is, for example,
As shown in FIG. 10, a guide rib 2 is provided on the printer main body such as the printer, which is continuous with the sheet conveyance path of the printer main body, and a guide rib 2 is provided below the guide rib 2 and rotated by a rotating shaft 3a. A switching claw 3 movably supported is provided with its front end facing the front of the transport path 1, and is in a second position in which it is tilted with the front end facing upward by being urged by a spring 4. Although not shown, the switching claw 3 is connected to a solenoid that is driven by a drive circuit and that rotates the switching claw 3 to a first position whose upper surface is along the transport path 1. In addition, a filler sensor 5 is urged so as to be upright in front of the transfer path 1 of the switching claw 3 and swingably supported, and further in front of it is driven by a drive motor 6. A switchback section having a pair of switchback rollers 7 is provided.

When recording is performed on the other side of the sheet which has been recorded on one side by the printer body, a solenoid (not shown) is driven to rotate the switching claw 3 against the urging force of the spring 4. The upper surface is the first position along the transport path 1. Then, the one-side recorded sheet which has been conveyed from the printer main body is sent to the switchback section along the guide ribs 2 and is conveyed by the switchback roller 7. At that time, the filler sensor 5 is tilted by the sheet, and the sheet passes over it. The rear end of the conveyed sheet is the filler sensor 5.
When passing over, the filler sensor 5 stands up and
To detect the passage of a signal and send a signal to a control circuit (not shown),
The control circuit gives a command to stop driving the solenoid. Then, the switching claw 3 is rotated to the second position by the spring 4, and the drive motor 6 of the switchback unit is reversely driven to reverse the switchback roller 7 to switch the sheet back. The switching claw 3 guides and re-feeds the paper to the printer body.

[0004]

However, the above-mentioned sheet re-feeding device requires a solenoid as a drive source for switching the switching claw 3 and its drive circuit, a spring 4 for urging the switching claw 3, and the like. there were. Therefore, the cost is increased because they are provided, and the useful life of the device is shortened due to wear of those parts.

Further, the front and rear ends of the sheet are directly filled with filler.
The sensor 5 is used for detection, and the filler sensor 5 is required to have a space corresponding to the swing due to the nature of swinging and sensing the passage of the sheet. Therefore, the switching claw 3
Distance L between the tip and the nip portion 8 of the switchback roller 7
As shown in FIG. 11, the reverse margin D (the distance for preventing the rear end of the sheet from coming off from the nip portion 8 at the time of switchback) becomes smaller as shown in FIG. There is a danger of leaving the seat. d
Indicates the distance that the sheet moves before the filler sensor 5 detects the sheet end and reverses the switchback roller 7. Therefore, when an attempt is made to increase the size of the reversing margin D, as shown in FIG. 10, the distance L between the tip of the switching claw 3 and the nip portion 8 increases, and the size of the apparatus increases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce the cost of the re-feeding device and increase its service life, and also to downsize the device and enable reliable re-feeding.

[0007]

Therefore, according to the present invention as set forth in claim 1, for example, as in the following illustrated embodiment, the sheet 20 on which one side is recorded is switched back with the switching claw 35 as the first position. It is sent to the portion 26, and then the switching claw 35
Is switched to the second position, and the switchback roller 39 of the switchback unit 26 is reversed to rotate the shutter
In the sheet re-feeding device 11 of the sheet recording apparatus, the sheet 20 is switched back and guided by the switching claw 35 to re-feed the sheet.
With the sheet 20 after the one-sided recording sent to the switchback section 26, the switching claw 35 can be rotated to the first position, and the switching claw 35 can rotate in the second position direction by gravity. In addition to the above, it is provided with a detection sensor such as a photo interrupter 38 which detects the switching pawl 35 when the switching pawl 35 reaches the second position due to its rotational habit and reverses the switch back roller 39. , Is characterized.

Further, according to a second aspect of the present invention, for example, as in the following illustrated embodiment, in the sheet re-feeding device 11 of the sheet recording apparatus according to the first aspect, the switching claw 35 is rotated. A weight 37 is directly or indirectly attached to the moving center shaft 34 to give the switching claw 35 a turning habit by gravity.

Further, according to a third aspect of the present invention, for example, as in the following illustrated embodiment, in the sheet re-feeding device 11 of the sheet recording apparatus according to the first aspect, the switching claw 35 is rotated. A detected member such as an arm 36 is provided on the moving center shaft 34, and an optical sensor such as a photo interrupter 38 is used as the detection sensor, and the optical sensor detects the detected member. It is characterized by

Further, according to a fourth aspect of the present invention, the sheet re-feeding device 11 of the sheet recording apparatus according to the first aspect is arranged at the position of the switching claw 35 as shown in the following illustrated embodiment. The guide ribs 42 for guiding the one-side recorded sheet 20 and the second ribs between the guide ribs 42.
The stopper 43 against which the switching claw 35 in the position abuts
And are provided.

[0011]

According to the first aspect of the invention, when the sheet 20 after one-sided recording is conveyed, the switching claw 35 is switched to the first position, and the rear end of the sheet 20 is switched claw 35. When passing the position, the switching claw 35 is switched to the second position due to the habit of turning due to gravity. This is detected by the detection sensor, the switchback roller 39 is rotated in the reverse direction, and the sheet 20 having one side recorded is sent to the switchback section 26.

According to the second aspect of the invention, when the sheet 20 passes, the weight 37 gives a turning habit by gravity.

According to the third aspect of the invention, the member to be detected is moved as the switching claw 35 is rotated, the member to be detected is detected by the optical sensor, and the switchback roller 39 is reversed.

Further, in the invention of claim 4, the guide rib 42 guides the one-side recorded sheet 20 to the switchback portion 26 and feeds it. Further, the switching claw 35 in the second position hits the stopper 43 and stops.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 9 is a schematic configuration diagram showing the entire laser printer. Reference numeral 10 in the drawing denotes the printer body. A drum-shaped photosensitive member 12 is provided in the printer main body 10 substantially at the center. Around the photoconductor 12, the charging device 13 and the developing device 1 are sequentially arranged in the driving direction indicated by the arrow.
4, a transfer device 15, and a cleaning device 16 are arranged. An optical writing device 17 is arranged below the charging device 13 and the cleaning device 16, and a paper feeding cassette 18 is detachably attached to the side of the developing device 14.

The sheet 20 fed from the sheet feeding cassette 18 by the sheet feeding roller 19 is conveyed to the upper side of the photoconductor 12 at a timing by the registration roller pair 21. The photoconductor 12 is driven in the counterclockwise direction as shown by the arrow, and at that time, the surface thereof is uniformly charged by the charger 13, and the laser beam L from the optical writing device 17 is irradiated to the photoconductor 12. Form an electrostatic latent image. This latent image is visualized by toner as it passes through the developing device 14. Then, this visible image is transferred by the transfer device 15 to the lower surface of the sheet 20 conveyed to the upper side of the photoconductor 12. The transferred sheet 20 is conveyed to a fixing device 22, a visible image is fixed, and the sheet is ejected to a sheet ejection unit 23. On the other hand, the residual toner on the photoconductor 12 after the transfer of the visible image is removed by the cleaning device 16.

On the printer body 10 as described above, as shown in FIG.
Can be attached. The sheet re-feeding device 11 includes a sheet conveying section 24 and a sheet reversing section 25.
4 is provided on the printer body 10 from the sheet discharge side of the printer body 10, and a sheet reversing section 25 is provided on the printer body 10 following the sheet conveying section 24.

The sheet transport unit 24 includes a printer body 10
Of the sheet discharge side is provided with two conveying paths, one conveying path serving as a discharging path 27 to a paper discharging unit attached outside the printer body 10, and the other conveying path serving as a sheet discharging path. The conveyance path 28 to the reversing unit 25. A switching claw 30 operated by the solenoid 29 is provided at the branch point. A plurality of pairs of first, second, and third conveyor rollers 32a, 32b, and 32c are provided in the conveyor path 28, and the rollers below the conveyor rollers 32a, 32b, and 32c.
The conveyor belt 32 is stretched between the rollers. Then, the lower roller of the first transport roller 32a can be driven by the motor 31.

On the other hand, the sheet reversing unit 25 has a structure shown in FIGS.
It is configured as shown in. That is, the pair of left and right side plates 33a
Is provided, the guide plate 33 is attached between both side plates 33a, and the upper surface is extended along the extension of the transport path 28 of the sheet transport unit 24. In addition, between the side of the sheet conveying section 24 of both side plates 33a, a rotation center shaft 34 located below the conveying path 28 is rotatably supported. And, on the rotation center shaft 34,
The switching claw 35 is attached, and the tip end is directed to the side opposite to the sheet conveying section 24. Further, as shown in FIG. 3, a base end of an arm 36 orthogonal to the axis is attached to one end of the rotation center shaft 34, a weight 37 is provided at its tip, and one end of the guide plate 33 is provided. A photo interrupter 38 is provided. The photo interrupter 38 is provided with a notch 38a in which the arm 36 can freely intervene. Further, as shown in FIG. 1, a pair of switchback rollers 39 are provided in front of and below the switching pawl 35 at positions above and below the guide plate 33, and a switchback roller 39b below the switchback rollers 39b is provided on the guide plate 33. Open window 3
A portion of the roller 3a is seen through from 3b and is pressed against the upper roller 39a. The drive motor 41 is configured to transmit the rotation to the lower roller 39a via the belt 40, and the portion having the switchback roller 39 is the switchback section 26. Further, in the upper part of the sheet reversing section 25,
As shown in FIG. 4, a plurality of guide ribs 42 guide the sheet from the conveying path 28 to the switchback roller 39 at the lower edge 42a, and a plurality of ribs positioned above the lower edge 42a. A stopper 43 is provided. Then, the stopper 43 is located at a position vertically corresponding to the switching claw 35.

Further, as shown in FIG. 5, the control unit 46 of the sheet re-feeding device 11 analyzes the signal from the control device 45 of the printer body 10 by a software-aware process, and the CPU 47 and the signal from the CPU 47. It has drivers 48, 49 and 50 for inputting and sending signals to the motor 31, the drive motor 41, the solenoid 29, etc., respectively.
Then, it is connected to the control device 45 of the printer body 10 by a serial line. The CPU 47 has two sensors, that is, the motor 31 which is a trigger source for timing the sheet conveyance.
A sheet detection sensor 44 provided in the vicinity and a photo interrupter 38 provided in the vicinity of the rotation center shaft 34 of the switching pawl 35 are connected.

When the sheet 20 recorded on the printer body 10 and recorded on one side is ejected as it is, the control unit 4 receives a signal from the control device 45 of the printer body 10.
The solenoid 29 is turned off by the driver 50 of No. 6 to switch the switching claw 30, and the sheet 20 is discharged to the paper discharge portion through the paper discharge path 27.

When recording on both sides of the sheet, the driver 50 of the control unit 46 turns on the solenoid 29 in response to a signal from the control device 45 of the printer body 10 to move the switching claw 30 toward the conveyance path 28. And the drivers 48 and 49 drive the motor 31 and the drive motor 41. Then, the single-sided recorded sheet recorded by the printer body 10 is sent to the sheet reversing section 25 through the conveyance path 28 of the sheet conveying section 24. Sheet 20 is guide rib 4
When the sheet is conveyed along the second guide surface 42a, the tip is pressed by the sheet 20 as shown in FIG. 6, and the switching claw 35 is rotated so that gravity is applied as shown by the alternate long and short dash line in FIG. The upper surface of the guide rib 42 is switched to a first position substantially parallel to the lower edge 42a of the guide rib 42. Then, the sheet 20 is sent to the switchback unit 26, and the tip thereof is switchedback.
When the sheet reaches the roller 39, the sheet 20 is conveyed by the switchback roller 39. When the rear end of the conveyed sheet 20 passes over the front end of the switching claw 35, the switching claw 35 is moved to the weight 3
It rotates counterclockwise due to the habit of turning by gravity 7 and, as shown in FIG. 4, its tip comes into contact with the stopper 43 and switches to the second position shown by the solid line in FIG. Then, the photo interrupter 38 detects the lever 36 and detects the drive motor 4
1 is reversed and the switchback roller 39 is reversed.
Then, the sheet 20 is switched back to switch the claw 35.
, And re-feed the paper to the printer body 10.

This is shown in a chart as shown in FIG.
When the motor 20 is being sent by the normal rotation of the drive motor 41, the photo interrupter 38 is in the ON state. When the rear end of the sheet 20 passes the tip position of the switching claw 35, the switching claw 35 switches to the second position, and the photo interrupter 38 detects the arm 36 and switches from ON to OFF. , The motor 41 is instantly reversed. for that reason,
The distance d that the rear end of the seat 20 travels is extremely short before the photo interrupter 38 detects the arm 36 and the drive motor 41 starts reverse rotation. Therefore, the distance (margin at the time of reversal) D for preventing the rear end of the sheet 20 from separating from the switchback roller 39 is the tip position of the switching claw 35 and the switchback roller 39. It is a long distance that occupies most of the distance L from the nip position.

[0025]

Therefore, according to the first aspect of the present invention, the detection sensor detects that the switching claw has rotated to the second position due to the habit of rotation due to gravity, and the switchback lock.
Since the rotor is reversed, an urging member for urging the switching claw, a solenoid for rotating the switching claw, and a drive circuit thereof are not required. Therefore, the cost of the re-feeding device can be reduced, and since there is no risk of wear or failure of those parts, the service life of the device can be increased. Also, since a filler sensor is not used, reliable re-feeding can be performed even if the length of the transport path is short.
The device can be downsized.

Further, according to the second aspect of the invention, when the sheet passes, the switching claw gives a turning habit by gravity by the weight, so that the sheet can be reliably re-fed with a simple structure. ..

Further, according to the third aspect of the invention, since the switchback roller is reversed by detecting the member to be detected by the optical sensor when the switching claw is rotated, the re-feeding can be surely performed with a simple structure. Paper becomes possible.

According to the fourth aspect of the invention, since the sheet on which one side has been recorded is guided to the switchback portion by the guide ribs and fed into the switchback portion, the sheet can be reliably guided and the sheet can be reliably guided.
Since the switching claw that pivots to the second position of the switch abuts against the stopper and stops, the switching claw can be reliably positioned at the second position.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a re-feeding device that is an embodiment of the present invention.

FIG. 2 is a perspective view showing the printer body with an upper portion of the sheet reversing unit removed.

FIG. 3 is a detailed view of the vicinity of the rotation center axis end of the sheet reversing portion.

FIG. 4 is a configuration diagram showing a positional relationship among a guide rib, a stopper and a switching claw.

FIG. 5 is a block diagram showing a control unit of the re-feeding device.

FIG. 6 is a configuration diagram showing a positional relationship among a guide rib, a stopper, and a switching pawl in the sheet conveyance state.

FIG. 7 is a chart showing the relationship between the position of the rear end of the sheet and motor rotation switching by the photo interrupter.

FIG. 8 is a schematic configuration diagram showing a laser printer and a sheet re-feeding device provided therein.

FIG. 9 is a schematic configuration diagram of a laser printer main body.

FIG. 10 is a schematic configuration diagram of a sheet reversing unit in a conventional re-feeding device.

FIG. 11 is an explanatory diagram showing a problem in a state where the length of the conveyance path of the sheet reversing unit is shortened.

[Explanation of symbols]

 11 Refeeding Device 20 Sheet 26 Switchback Section 34 Rotation Center Shaft 35 Switching Claw 36 Arm (Detected Member) 38 Photointerrupter (Optical Sensor) 39 Switchback Roller 42 Guide Rib 43 Stopper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/00 108 7369-2H

Claims (4)

[Claims] 1. A switchback claw is set to a first position, a sheet recorded on one side is sent to a switchback section, and then the changeover claw is switched to a second position, and a switchback roller of the switchback section is reversed. Then, the sheet is switched back, and in the sheet refeeding device of the sheet recording device which guides the sheet by the switching claw and re-feeds the sheet, the sheet after the one-sided recording fed to the switchback unit, The switching claw is rotatable to the first position, and the switching claw is given a turning habit in the second position direction by gravity, and the switching claw is brought to the second position due to the turning habit. At this time, a sheet re-feeding device of the sheet recording apparatus, which is provided with a detection sensor that detects it and reverses the switchback roller. 2. The sheet recording apparatus according to claim 1, wherein a weight is directly or indirectly attached to a central axis of rotation of the switching claw to give the switching claw a rotational habit by gravity. Paper feeder. 3. The detection member is provided on the center axis of rotation of the switching claw, and an optical sensor is used as the detection sensor, and the detection member is detected by the optical sensor. Refeeding device for sheet recording device. 4. The switching claw position is provided with a plurality of guide ribs for guiding the one-side recorded sheet, and a stopper between the guide ribs, which abuts the switching claw at the second position. The sheet re-feeding device of the sheet recording apparatus according to claim 1.