JPH05165358A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To miniaturize a device without curling a sheet by holding the leading edge of the sheet after transfer by a nip part, detecting it and facing it to a paper ejecting direction. CONSTITUTION:An ejected paper receiver 23 is obliquely attached to a device main body 10, while a fixing device 21 is supported by the driving shaft 31a of a stepping motor 31 and the supporting position is set as a 1st position. The sheet 12 on which the image has been transferred is inserted in the nip part N of the fixing device 21 at the 1st position so as to fix a transferred image. The leading edge of the sheet 12 ejected from the fixing device 21 is detected by a sheet detecting means 30, which transmits a signal to drive the stepping motor 31 so as to turn the fixing device 21 from the 1st position to a 2nd position, then the nipped sheet 12 is ejected on the receiver 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on an electrophotographic system (a system for transferring an image formed on a photoconductor to a sheet for recording) using a laser, such as a printer, a copying machine and a facsimile. It can be applied to an electrophotographic apparatus for recording on a sheet. Specifically, the sheet after the image transfer is put in the nip portion of the fixing device, where heat and pressure are applied to fix the transferred image on the sheet, and the sheet after the fixing is placed on the paper receiving tray. To an electrophotographic device for discharging to

[0002]

2. Description of the Related Art Conventionally, for example, in a laser printer, an image on a photoconductor 1 is transferred onto a sheet by a transfer device 2,
The sheet after the image transfer is conveyed to heat the fixing device 3 by heating.
It is put in the nip portion between the roller 4 and the pressure roller 5, where heat and pressure are applied to fix the transferred image on the sheet, and the sheet after fixing is discharged as it is in the direction of the arrow, It is designed to be stacked on the discharge tray 6. Therefore, the paper output receiver 6
Has become substantially horizontal, the length A protruding from the main body of the apparatus has become longer, and the length B of the entire apparatus has become longer, resulting in an increase in size.

[0003]

However, if the paper discharge tray 6 is obliquely attached in order to shorten the protruding length A of the apparatus main body, the sheet is bent immediately after fixing.
However, there is a problem that the sheet is curled because the heat of fixing is still left in the sheet and the sheet cannot be stacked on the sheet receiving tray 6.

Therefore, the object of the present invention is to provide a sheet
It is to enable downsizing of the device without the need for

[0005]

Therefore, according to the first aspect of the invention, the sheet 12 after the image transfer is put in the nip portion N of the fixing device 21 as shown in the following illustrated embodiment,
Therefore, in an electrophotographic apparatus in which heat and pressure are applied to fix the transferred image on the sheet 12, and the sheet 12 after fixing is discharged onto a paper discharge tray 23, at least fixing means of the fixing device 21. 27 is rotatable between a first position in which the tip of the sheet 12 after image transfer is sandwiched in the nip portion N and a second position in which the sandwiched sheet 12 is directed in the direction of the discharged paper receiver 23. A sheet detecting means 30, 35, 36 for detecting a sheet and a driving means such as a stepping motor 31 for rotating the fixing means 27 according to a signal from the sheet detecting means 30, 35, 36 are provided. Is obliquely attached to the apparatus main body 10.

According to a second aspect of the present invention, there is provided an electrophotographic apparatus according to the first aspect of the present invention, for example, as in the embodiments shown in FIGS.
All of the fixing devices 21 including 7 are rotated.

According to a third aspect of the present invention, in the electrophotographic apparatus according to the first aspect, for example, as in the following embodiments shown in FIGS. 3 and 4, the fixing unit 21 of the fixing unit 21 is driven by the driving unit. It is characterized in that only the fixing means 27 is rotated.

The invention according to claim 4 is the electrophotographic apparatus according to claim 1, as in the embodiment shown in FIGS. 1 and 2, for example, in which the nip portion at the tip of the sheet 12 is used. N-sandwiched to N and the sheet receiving tray 23 of the sheet 12
Both of the upward discharge are detected by the one sheet detecting means 30.

The present invention as defined in claim 5 is the electrophotographic apparatus according to claim 1, as in the embodiment shown in FIGS. 3 and 4, for example. One of the sheet detecting means 35 is one that is sandwiched in N.
And the discharge of the sheet 12 onto the paper discharge tray 23 is detected by the other sheet detecting means 36.

[0010]

In the present invention, the sheet 1 after the image transfer is performed.
The tip of No. 2 is put in the nip portion N of the fixing device 21 and sandwiched, and the sheet detecting means 30, 35, 36 detect it, and the driving means fixes it by a signal from the sheet detecting means 30, 35, 36. The means is rotated from the first position to the second position, and the sandwiched sheet 12 is discharged onto the paper discharge tray 23. After the sheet is discharged, the driving means is operated again to return the fixing means from the second position to the first position.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a schematic configuration diagram showing the entire laser printer. The paper feed cassette 11 is removably loaded in the lower portion of the printer body 10. Paper cassette 1
The sheets 12 in 1 are fed one by one by a sheet feeding roller 13 and guided in a reversal direction in a conveying path 14 to form a pair of registration rollers 15.
Transport to. Then, the registration roller pair 15 conveys it to the upper side of the photoconductor 16 at a timing. The photoconductor 16 is rotated counterclockwise to charge the surface by the charger 17 and irradiate the surface with laser light from the laser optical system 18 to form an electrostatic latent image.

This latent image is visualized by toner as it passes through the developing device 19, and this visible image is transferred to the lower surface of the sheet 12 conveyed on the photoconductor 16 by the transfer device 20 to obtain the sheet. 12 is conveyed to the fixing device 21. The fixing device 21 has a fixing means 27 composed of a heating roller 25 and a pressure roller 26 which comes into pressure contact with the heating roller 25. The fixing means 27 fixes the transferred image on the sheet 12. To do. And the fixing device 2
The sheet 12 that has exited 1 is discharged onto the paper discharge tray 23 and stacked with the image side facing down. On the other hand, after the visible image is transferred, the photoconductor 16 is cleaned by the cleaning device 24 to remove the residual toner.

By the way, in the present invention, the paper discharge receiver 23 is provided obliquely with respect to the apparatus main body 10 so that the protruding length from the apparatus main body 10 is a, and the fixing device 21 is constructed as follows. That is, as shown in FIG.
A heating roller 25 containing a halogen heater 25a is supported on the case 28 of No. 1 and a pressure roller is placed on the heating roller 25.
The fixing means 27 is configured by urging and pressing the la 26 with a spring (not shown) or the like. On the paper discharge side of the fixing means 27,
A sheet discharge roller pair 29 supported by the sheet 28 is provided, and the fixing unit 2
The sheet detecting means 30 is provided on the case 28 between the sheet discharging roller pair 7 and the sheet discharging roller pair 29, and the lower end of the sheet detecting means 30 is swingably supported in the sheet discharging direction, and the front end side is directed toward the fixing means 27. Energize to stand upright. Reference numeral 22 is a separating claw whose tip is in contact with the heating roller 25.

A stepping motor 31, which is an example of a driving means, is provided in the apparatus main body 10 and its driving shaft 31a is provided.
Is parallel to the heating roller 25, one end of the lower side of the case 28 on the paper feeding side is fixed to the drive shaft 31a thereof to support the fixing device 21, and the heating roller 25 and the pressure roller 26 are supported. The nip portion N where and are brought into pressure contact with each other is an extension of the sheet conveying direction. Then, this position is referred to as a first position.

Then, the sheet 12 after the image transfer is sent to the fixing device 21 and put into the nip portion N, where heat and pressure are applied to fix the transferred image on the sheet 12. When the tip of the sheet 12 is sent out from the fixing means 27 and reaches the sheet detecting means 30, the sheet detecting means 30 is pushed by the sheet 12 and falls down to detect the sheet 12. A signal is sent to drive the stepping motor 31. Then, the fixing device 21 is rotated to the second position by the drive shaft 31a, and the sandwiched sheet 12 is discharged onto the discharge tray 23 as shown in FIG.

Then, the transferred image on the sheet 12 is fixed and sent out from the fixing device 21, and the sheet 12 after fixing is discharged onto a discharge tray 23. When the discharge of the sheet 12 is completed, the sheet detecting means 30 pushed down by the sheet 12 returns by an urging force and sends a signal. Then, the stepping motor 31 is driven in the reverse direction to drive the drive shaft 31a.
The fixing device 21 is returned to the first position as shown in FIG.

In the above embodiment, the fixing device 21 is entirely rotated, but it may be structured as shown in FIG. That is, the shafts of the heating roller 25 and the pressure roller 26 of the fixing means 27 are connected by the link 32. On the other hand, a disk 33 is attached to the drive shaft 31a of the stepping motor 31, and both ends of an arm 34 are rotatably connected to the peripheral edge of the disk 33 and the shaft of the pressure roller 26. Then, the nip portion N is located on the extension in the sheet conveying direction. Then, this position is referred to as a first position.

Then, a first sheet detecting means 35 for detecting the front end of the sheet 12 is provided on the sheet discharge side of the fixing means 27.
A second sheet detecting means 36 for detecting the rear end of the sheet 12 is provided on the case 28 near the paper discharge roller 29. In this embodiment, a paper discharge roller pair 29 is provided at a position before the paper discharge tray 23 in the case 28.

Then, the sheet 12 after the image transfer is sent to the fixing device 21 and put into the nip portion N, where heat and pressure are applied to fix the transferred image on the sheet 12. When the front end of the sheet 12 is sent out from the fixing means 27 and reaches the first sheet detecting means 35, the first sheet detecting means 35 detects the sheet 12 and sends a signal to the stepping mode. -Drive the disk 31 to rotate the disk 33. Then, the arm 34 pulls the pressure roller 26 side of the link 32, and the link 32 rotates about the heating roller 25,
The fixing means 27 is rotated to the second position as shown in FIG.
While holding down the second sheet detecting means 36, the sandwiched sheet 12 is ejected onto the sheet ejection tray 23.

Then, the transferred image on the sheet 12 is fixed and sent out from the fixing means 27, and the sheet 12 after fixing is fixed.
Are discharged onto the paper discharge tray 23. When the discharge of the sheet 12 is completed, the second sheet detecting means 36, which has been tilted by the sheet 12, returns to send a signal. Then, the stepping motor 31 is driven in the reverse direction to rotate the disk 33, and the link 32 is rotated by the arm 34 to move the fixing means 27 to the position shown in FIG.
Return to the first position as shown in.

[0021]

Therefore, according to the present invention, the front end of the sheet after the image transfer is inserted into the nip portion of the fixing device and sandwiched, and the sheet detecting means detects it to output a signal from the sheet detecting means. By the driving means, the fixing means is rotated from the first position to the second position, and the sandwiched sheet is directed in the oblique sheet ejection receiving direction. The device can be miniaturized without curling.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a main part of a laser printer according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state in which the fixing unit is rotated to a second position.

FIG. 3 is a schematic configuration diagram showing a main part of a laser printer which is another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a state in which the fixing unit is rotated to a second position.

FIG. 5 is an overall schematic configuration diagram of such a laser printer.

FIG. 6 is a schematic configuration diagram of a conventional laser printer.

[Explanation of symbols]

 10 Device Main Body 12 Sheet 21 Fixer 23 Paper Ejection Receiver 27 Fixing Means 30 Sheet Detecting Means 31 Stepping Motor (Drive Means) 35 First Sheet Detecting Means 36 Second Sheet Detecting Means N Nip part

Claims (5)

[Claims] 1. A sheet after image transfer is put in a nip portion of a fixing device, where heat and pressure are applied to fix the transferred image on the sheet, and the sheet after fixing is discharged. In an electrophotographic apparatus which discharges onto a receiving device, at least the fixing means of the fixing device is provided with a first position where the front end of the sheet after image transfer is sandwiched in the nip portion and a sheet which is sandwiched in the sheet receiving direction. It can be rotated to the second position facing
A sheet detecting means for detecting a sheet and a driving means for rotating the fixing means in response to a signal from the sheet detecting means are provided, and the discharge tray is obliquely attached to the apparatus main body.
Electrophotographic device. 2. The electrophotographic apparatus according to claim 1, wherein all of the fixing device including the fixing unit are rotated by the driving unit. 3. The electrophotographic apparatus according to claim 1, wherein only the fixing unit of the fixing unit is rotated by the driving unit. 4. The sheet detecting means detects both the sandwiching of the tip of the sheet into the nip portion and the discharging of the sheet onto the sheet receiving tray. The electrophotographic apparatus according to 1. 5. The sandwiching of the front end of the sheet into the nip portion is detected by one of the sheet detecting means, and the discharge of the sheet onto the sheet receiving tray is detected by the other. The electrophotographic apparatus according to claim 1.