JPH0659594A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To move a sheet feeding and moving part in optimum timing according as paper enters a suction unit and to follow up an actuating mode for the suction unit even when copying speed is made higher. CONSTITUTION:This device is provided with a fixing device 200 having an upper fixing part for a color mode and a lower fixing part for a black-and-white mode, and the suction unit 100 having the sheet feeding and moving part 117 capable of moving between a 1st position where the paper is fed to the upper fixing part and a 2nd position where the paper is fed to the lower fixing part; and the suction unit 100 is provided with a paper entering detection sensor 108 detecting paper entering the unit 100, so that the movement of the sheet feeding and moving part 117 is controlled based on the paper entering detecting action of the sensor 108.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a fixing device having three fixing rollers, first to third fixing rollers. The first and second fixing rollers have a pressure contact portion and the second and third fixing rollers have a pressure contact portion. The present invention relates to an electrophotographic apparatus in which a fixing portion is formed on each of the and.

[0002]

2. Description of the Related Art Conventionally, as a copying machine as an electrophotographic apparatus, there is known a copying machine provided with two fixing rollers, an upper fixing roller and a lower fixing roller. In such a copying machine, an original is scanned by a light source lamp, a photoconductor is exposed by reflected light from the original, and an electrostatic latent image formed on the photoconductor is developed by toner of a developing device. After the toner image is transferred onto the sheet, the sheet is nipped and conveyed between the fixing rollers of the fixing device so that the toner image corresponding to the image of the original is fixed on the sheet.

As the copying machine as described above, a copying machine corresponding to each of the color and black and white copy modes has been proposed. However, such a copying machine can be used for both the color and black and white modes. Since the material of the fixing roller in the fixing device is limited to a single material, the types of sheets that can be used in both modes are limited.

Therefore, a copying machine capable of the above-mentioned color and monochrome copying modes is disclosed in Japanese Patent Laid-Open No. 51-980.
As disclosed in Japanese Patent Laid-Open No. 36-36, there has been proposed a fixing device provided with three fixing rollers of upper, middle, and lower. In this copying machine, the first fixing portion is formed between the upper and middle fixing rollers, and the second fixing portion is formed between the middle and lower fixing rollers, so that the first and second fixing rollers are formed. Each fixing unit is set as a fixing unit corresponding to a color or monochrome copy mode.

Thus, in the above copying machine, it is possible to use sheets made of various materials such as paper, label, mylar, and polycarbonate by appropriately selecting the materials of the upper, middle and lower fixing rollers. ing.

It should be noted that such a copying machine is provided with a sheet conveying device movable between a first position for conveying a sheet to the first fixing section and a second position for conveying a sheet to the second fixing section. The sheet transporting device is provided so that it is moved between the fixing units by a user operating the operation panel.

[0007]

However, in the copying machine in which the selection range of sheets to be used is expanded by forming the first and second fixing portions as in the above-mentioned conventional method, the copying modes of color and black and white are used. Accordingly, the sheet conveying device must be moved by a user operation. For this reason, when copying in a mixture of color and black and white modes such as color to black and white or black and white to color, the sheet conveying device must be moved in accordance with each mode. Moreover, there is a problem that continuous copying cannot be automatically performed in each mode.

[0008]

In order to solve the above-mentioned problems, an electrophotographic apparatus according to the present invention has a first to a third structure.
A first fixing portion is formed at a pressure contact portion between the first fixing roller and the second fixing roller, and a second fixing portion is formed at a pressure contact portion between the second fixing roller and the third fixing roller. Is
A fixing device that feeds the sheet conveyed to each fixing unit in the discharge direction by the rotation of the fixing roller, a first position that conveys the sheet to the first fixing unit, and a second position that conveys the sheet to the second fixing unit. The following means are taken in an electrophotographic apparatus provided with a sheet transporting device movably provided between them.

That is, the above-described sheet conveying device is provided with a sheet detecting means for detecting a sheet, and has a first position and a second position.
The movement to and from the position is performed based on the sheet detecting operation of the sheet detecting means.

[0010]

According to the above structure, when the sheet detecting means detects the supply of the sheet to the sheet conveying device, the sheet conveying device is moved to the first or second position based on the detection of the supply of the sheet to the sheet conveying device. First or second fixing device
The sheet is conveyed to the fixing unit. Therefore, the sheet conveying device can be moved at an optimum timing according to the supply of the sheet to the sheet conveying device, and the operation of the sheet conveying device can be made to follow even if the copy speed is increased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

A full-color copying machine (hereinafter simply referred to as a copying machine) as an electrophotographic apparatus in this embodiment is shown in FIG.
As shown in FIG. 1, the copying machine main body 1 and the reversing and retransmitting unit 2 provided below the copying machine main body 1 are provided.

The main body 1 of the copying machine has an original placing table 3 made of hard transparent glass on the upper surface thereof, and an exposure optical system section 4 under the original placing table 3. This exposure optical system section 4
Is a lamp unit 5 that scans an original document (not shown) placed on the original document table 3 while irradiating it with light, a plurality of reflecting mirrors 6 that guide reflected light from the original document to the photoconductor 8, The lens unit 7 is arranged in the optical path of the reflected light.

A charging charger 9 for charging the surface of the photoconductor 8 to a predetermined potential is provided on the outer circumference of the photoconductor 8. Further, the charging direction of the photoconductor 8 from the charge charger 9 (A
Direction), an inter-image eraser (not shown), a black developing tank 10, a yellow developing tank 11, a magenta developing tank 1
2, a cyan developing tank 13, an intermediate transfer device 14, a cleaning device 15, and a charge eliminating device 16 are arranged in this order.

The intermediate transfer device 14 is the transfer belt 1
7. Rollers 18, 19 supporting this transfer belt 17
20, the transfer belt 17 is pressed against the photosensitive member 8
The first transfer rollers 21 and 21 that transfer the toner image formed on the surface to the transfer belt 17, and are pressed against the roller 20 when the toner image is transferred onto the sheet as a sheet, and the toner image on the surface of the transfer belt 17 is transferred onto the sheet. A second transfer roller 22 for transferring and a cleaning device 23 for removing residual toner on the surface of the transfer belt 17 are provided.

A registration roller 24, a paper feed cassette 25, and a paper feed tray 26, which feed the paper to the intermediate transfer device 14 at a predetermined timing, are provided on the paper feed side of the intermediate transfer device 14. A paper feed roller 27, a transport roller 28, and the like are provided near the cassette 25 and the paper feed tray 26.

A suction unit 100 as a sheet conveying device for conveying a sheet, a fixing device 200, a switching gate 29, a sheet discharging roller 30, and a sheet discharging tray 31 are provided in a sheet discharging direction from the intermediate transfer device 14. There is. The switching gate 29 is configured to switch the conveying direction of the sheet discharged from the fixing device 200 between the discharging roller 30 direction and the lower conveying path 32 direction.

The above-mentioned transport path 32 is the reversal retransmission unit 2
Of the fixing device 200 is conveyed, and the sheet is discharged onto the intermediate tray 33 with the surface on which the toner image is formed facing up. The sheets sent by the conveying path 32 are stacked on the intermediate tray 33, and the sheets are fed by the sheet feeding roller 3
4, the sheet is sent to the transport path 35. The conveyance path 35 is adapted to reverse the sheet sent from the intermediate tray 33 and convey it to the registration rollers 24.

As shown in FIG. 2, the fixing device 200 includes an upper heat roller 201, which is a first fixing roller, and a middle heat roller 202, which is a second fixing roller. And a lower heat roller 203 which is a fixing roller. The upper heat roller 201 and the middle heat roller 202, and the middle heat roller 202 and the lower heat roller 203 are pressed against each other, and an upper fixing portion (first fixing portion) is formed at a pressure contact portion between the upper heat roller 201 and the middle heat roller 202. ) Is a fixing unit at the time of full-color copying, and is a lower fixing unit (second fixing unit) formed at a pressure contact portion between the middle heat roller 202 and the lower heat roller 203.
Is the fixing unit for black and white copying. Therefore, the surface layer is made of silicon rubber for the upper heat roller 201, Teflon for the middle heat roller 202, and silicon rubber or another suitable rubber for the lower heat roller 203. The surface of the upper heat roller 201 is a very smooth surface in order to obtain high releasability from the three-layer toner image for obtaining a full-color image.

In the suction unit 100, as shown in FIG. 3, two conveyor belts 101 are supported by a drive shaft 102 on the paper input side and a driven shaft 103 on the paper output side, and the drive shaft 102 is a belt. By being rotated by the power transmitted from a drive motor (not shown), the sheet is circulated in the B direction, which is the sheet conveying direction. The drive shaft 102 is rotatably supported by the back plate 104 and the front plate 105, and the driven shaft 103 is
The suction plate 106 is rotatably supported at the paper output side end. Suction plate 106 is drive shaft 1
The suction case 1 is attached so as to be vertically movable around the 02 side and has a suction fan inside on the lower surface thereof.
07 is provided.

An opening 10 is provided between the conveyor belts 101 on the suction plate 106.
6a is formed, and the rod portion 10 of the sheet input detection sensor (sheet detection unit) 108 that detects that a sheet has entered the suction unit 100 through the opening 106a.
8a is protruding.

Below the suction case 107, a cam shaft 109 is rotatably supported by the back plate 104 and the front plate 105, and the cam shaft 109 is provided.
In the portion corresponding to the lower surface of the suction case 107, two eccentric cams 110, 110 are eccentric in the same direction.
Is provided. Cam shaft 109 on the back plate 104
An idle shaft 111 is provided in the vicinity of, and a timing belt 114 is hung between the sprocket 112 and 113 provided on the idle shaft 111 and the drive shaft 102. A gear 115 provided on the idle shaft 111 meshes with an input gear 116a of a spring clutch 116 provided on the cam shaft 109.

As a result, the rotation of the drive shaft 102 is transmitted to the cam shaft 109 via the sprocket 113, the timing belt 114, the sprocket 112, the idle shaft 111, the gear 115, and the spring clutch 116, and the eccentric cams 110 and 110 are used. Suction case 1
The lower surface of 07 is pushed, and the sheet conveyance moving unit 117 is moved up and down.

The above-described sheet conveying / moving section 117 includes the suction plate 106 and the conveying belts 101, 10.
1 and the like, which move up and down, to a first position where the sheet is conveyed to the upper fixing portion of the fixing device 200 when moved upward, and to the fixing device when moved downward. The second fixing unit 200 is arranged at each of the second positions where the sheet is conveyed to the lower fixing unit.

The full-color copying operation in the copying machine having the above-mentioned structure will be described below.

First, the surface of the photoconductor 8 rotating in the A direction is uniformly charged by the charging charger 9, and the exposure optical system unit 4 scans the original on the original placing table 3 for the first time. The reflected light from the document passes through a blue color separation filter (not shown) and a slit (not shown),
The exposure point on the surface of the photoconductor 8 between the charging charger 9 and the inter-image eraser is irradiated, and the photoconductor 8 is exposed to form an electrostatic latent image. Next, the potential of the non-image area on the photoconductor 8 is removed by the inter-image eraser, and then the electrostatic latent image is developed by the yellow developing tank 11 to form a yellow toner image.

Next, the yellow toner image on the surface of the photoconductor 8 is transferred onto the transfer belt 17 which moves in the C direction by the first transfer roller 21 to which a negative high voltage is applied. The residual toner on the surface of the photoconductor 8 is removed by the cleaning device 15, and the residual charge on the surface of the photoconductor 8 is removed by the charge eliminating device 16.

When the above series of operations is completed, the photoconductor 8 is charged again by the charging charger 9, the original is cooked, and the exposure optical system section 4 performs the second scanning. In this case, the green color separation filter is used and the photoconductor 8
The electrostatic latent image formed on is developed with magenta toner in the magenta developing tank 12. The magenta toner image formed on the surface of the photoconductor 8 is formed by the first transfer roller 2
1, the toner image is transferred onto the yellow toner image on the transfer belt 17 in an overlapping manner. Thereafter, in the same manner, a third scanning is performed by the exposure optical system unit 4 using the red color separation filter, and a cyan toner image is formed on the photoconductor 8 by the development with the cyan toner in the cyan developing tank 13. It is formed. This cyan toner image is transferred onto the magenta toner image on the transfer belt 17.

Next, the second transfer roller 22 separated from the transfer belt 17 in the operation so far is transferred to the transfer belt 1.
When the sheet is pressed against 7 and a negative potential higher than the surface potential of the transfer belt 17 is applied to the second transfer roller 22, the sheet is conveyed from the sheet feeding cassette 25 or the sheet feeding tray 26 through the registration roller 24. The three-layer toner image on the main body 17 of the copying machine is transferred onto the sheet.

The above-mentioned paper on which the toner image is transferred is transferred to the upper fixing portion formed at the pressure contact portion between the upper heat roller 201 and the middle heat roller 202 of the fixing device 200 by the conveyor belts 101, 101 of the suction unit 100. Be transported. In the upper fixing section, the three-layer color toner images on the paper are heated and melted by the upper and middle heat rollers 201 and 202 and fixed on the paper. Then, the paper discharged from the fixing device 200 is discharged onto the paper discharge tray 31 by the paper discharge rollers 30.

Next, the black-and-white copying operation of this copying machine will be described.

First, the surface of the photoconductor 8 is charged by the charger 9.
Are uniformly charged, and the exposure optical system unit 4 scans the document on the document table 3. The reflected light from the document is guided to the exposure optical system unit 4 and irradiates the photoconductor 8 without passing through the color separation filter and the slit, and an electrostatic latent image is formed on the photoconductor 8. After that, the electrostatic latent image is developed by the black developing tank 10, and the black toner image formed by this is transferred to the transfer belt 17,
Furthermore, it is transferred to the paper.

The paper on which the above-mentioned toner image has been transferred is conveyed belt 101.1 of suction unit 100.
01 by the middle heat roller 202 and the lower heat roller 20
The toner image is conveyed to the lower fixing unit formed at the pressure contacting portion with 3, and the toner image is fixed on the paper.

In the case of one-sided copying, the switching gate 29 operates so as to guide the paper toward the paper discharge roller 30, and the paper discharged from the fixing device 200 is discharged from the paper discharge roller 30. The sheet is discharged onto the paper tray 31.

On the other hand, in the case of double-sided copying, the switching gate 29 operates so as to guide the sheet toward the conveying path 32, and the sheet discharged from the sheet discharging roller 30 is conveyed to the conveying path 32.
Is discharged onto the intermediate tray 33. After that, the paper on the intermediate tray 33 is conveyed by the paper feed roller 34 to the conveyance path 35.
To the registration roller 24 by being reversed by the conveyance path 35.

Next, the surface of the photoconductor 8 is charged by the charger 9.
Then, the exposure optical system section 4 scans the original placed on the original placing table 3 with the exposure optical system section 4 turned upside down.
Next, the toner image is transferred to the back surface of the sheet by the same operation as described above, and the toner image is fixed on the sheet by the lower fixing unit. After that, the sheet is guided by the switching gate 29 toward the sheet discharge roller 30, and is discharged onto the sheet discharge tray 31 by the sheet discharge roller 30.

Next, the suction unit 1 in each of the above-described full-color copy and monochrome copy modes.
The operation process of No. 00 will be described below based on the flowcharts of FIGS. 4, 5, and 6.

First, it is determined whether or not paper has entered the suction unit 100 from the intermediate transfer device 14 side.
It is determined by 08 (S1). When the ON state of the paper feed detection sensor 108 is determined in S1, a suction timer and a jam timer (not shown) are set (S
2) Then, it is determined whether or not the suction timer overflows (S3).

Next, when the suction timer overflow is detected in S3, the next copy mode is determined (S4). If it is determined in S4 that the next copy mode is black and white, the process proceeds to S5 and the process shown in FIG.
Call the subroutine shown in. In this subroutine, first, it is determined whether the current copy mode is color or black and white (S51). If it is determined in S51 that the current copy mode is black and white, that is, the next copy mode and current If the black and white copy mode is the same,
The subroutine is terminated in this state, and S7 described later is executed.
Move to.

On the other hand, when it is determined in S51 that the color mode is selected, the sheet conveying / moving unit 117 of the suction unit 100 is rotated downward about the drive shaft 102 to obtain the current color mode. The sheet conveyance moving unit 11 moves from the first position to the second position for the next black and white mode.
7 is moved (S52), and the process proceeds to S7 described later.

If it is determined in S4 that the next copy mode is color, the process proceeds to S6,
The subroutine shown in FIG. 6 is called. In this subroutine, first, it is determined whether the current copy mode is color or monochrome (S61), and if it is determined in S61 that the color mode is selected, that is, the next copy mode and the current copy mode are determined. If the color is the same as the copy mode of, the subroutine is ended in that state,
The process proceeds to S7 described later.

On the other hand, when it is determined in S61 that the sheet is in the monochrome mode, the sheet conveying / moving unit 117 of the suction unit 100 is rotated upward about the drive shaft 102 to obtain the current monochrome mode. The sheet conveying / moving unit 117 moves from the second position to the first position for the next color mode.
(S62), and the process proceeds to S7, which will be described later.

At S7, the completion of the paper output from the suction unit 100 is determined by the paper input detection sensor 108. At S7, the paper-feed detection sensor 108 continues to turn on O.
In the N state, that is, when it is determined that the paper output from the paper input detection sensor 108 is incomplete, the process proceeds to S8, and it is determined whether the jam timer set in S2 has overflowed. It is determined (S8). If it is determined in S8 that the overflow has not occurred, S7 is executed again.
On the other hand, if it is determined that the paper has overflowed, a paper jam in the suction unit 100, that is, a jam is detected, and the occurrence of a jam is displayed on the display unit (not shown) (S9). .

On the other hand, in S7 described above, the paper entry detection sensor 1
When the OFF state of 08 is determined, that is, when it is determined that the ejection from the suction unit 100 is completed, the presence or absence of the next copy is determined (S10). If it is determined in S10 that there is a next copy, the process returns to S1 again, while if it is determined that there is no next copy, the suction unit 100 The operation is terminated.

Next, the continuous switching in each of the above-described full-color copy and monochrome copy modes will be described below with reference to the timing chart of FIG.

First, when the paper entry detection sensor 108 is turned on along with the entry of paper into the suction unit 100, the detection signal of the paper entry detection sensor 108 rises (H level), and this edge triggers a control circuit (not shown). The jam timer and the suction timer inside are set at the respective positions. At this time, the value of each timer that is set has a unique value that varies depending on the length of the copy paper.

Each timer set is
An interrupt is generated in the control circuit at the position. At this time, as shown in the figure, when the copy paper passes within a predetermined time, that is, the paper-in detection sensor 108 is turned off within a predetermined time.
In the case of FF, the output of the paper feed detection sensor 108 changes at the timing of (L level indicating that there is no paper), and thereafter, and interrupts occur. If an interrupt occurs before the edge of the detection signal, it is regarded as a copy jam.

If such a jam determination is performed and it is not regarded as a jam, the suction mode is switched from the color mode to the black and white mode by an interrupt generated at the timing of. On the contrary, when switching from the monochrome mode to the color mode, the switching is also performed at this timing.

As described above, in the electrophotographic apparatus of this embodiment, the fixing device 200 having the upper fixing section for the color mode and the lower fixing section for the monochrome mode, and the first sheet conveying the sheet to the upper fixing section. And a suction unit 100 having a sheet transport moving unit 117 that is movable between a position and a second position for transporting a sheet to a lower fixing unit. By including the paper-feeding detection sensor 108 for detecting the sheet feeding, the movement of the sheet conveying / moving unit 117 is controlled based on the paper-feeding detection operation of the paper-feeding detection sensor 108.

Therefore, the sheet conveying / moving unit 117 can be moved at an optimum timing in accordance with the entry of paper into the suction unit 100. Therefore, even if the copy speed is increased, the operation mode of the suction unit 100 is tracked. In addition, the copy mode can be changed from color to black and white, or black and white to color.
It enables continuous copying in both color and black and white modes.

The above embodiment is not intended to limit the present invention, and various modifications can be made within the scope of the present invention.
For example, in the above embodiment, paper is used as a sheet for copying an image of an original, but the sheet is not particularly limited to this, and sheets made of various materials such as a label, mylar, and polycarbonate are used as the sheet. It is also possible to do so.

[0052]

As described above, according to the electrophotographic apparatus of the present invention, the sheet conveying apparatus is provided with the sheet detecting means for detecting the sheet, and the movement between the first position and the second position is detected by the sheet. The configuration is performed based on the sheet detecting operation by the means.

As a result, the sheet conveying device can be moved at an optimum timing according to the supply of the sheet to the sheet conveying device, and the operation mode of the sheet conveying device can be followed even if the copying speed is increased. become.
In addition, even when copying in mixed modes of color and black and white, such as copying from color to black and white or from black and white to color, it is necessary to move the sheet conveying device according to each mode one by one. In other words, it is possible to automatically perform continuous copying in each mode.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a copying machine according to an embodiment of the present invention.

FIG. 2 is a side view showing a suction unit and a fixing device which constitute the copying machine.

FIG. 3 is a perspective view showing the suction unit.

FIG. 4 is a flowchart showing an operation process of the suction unit in each of full-color copy mode and monochrome copy mode.

5 is a flowchart showing a subroutine in the monochrome mode in the operation process of FIG.

FIG. 6 is a flowchart showing a subroutine in the color mode in the operation process of FIG.

FIG. 7 is a timing chart showing continuous switching in each mode of full-color copy and monochrome copy.

[Explanation of symbols]

 100 Suction Unit (Sheet Conveying Device) 108 Paper Input Detection Sensor (Sheet Detection Unit) 200 Fixing Device 201 Upper Heat Roller (First Fixing Roller) 202 Middle Heat Roller (Second Fixing Roller) 203 Lower Heat Roller (Third Fixing Roller) )

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazunori Iwasa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (1)

[Claims] 1. A first to a third fixing roller having three fixing rollers, wherein the first fixing roller and the second fixing roller have a first pressure contact portion.
A fixing unit is formed, a second fixing unit is formed at a pressure contact portion between the second fixing roller and the third fixing roller, and the sheet conveyed to each fixing unit is fed in a discharge direction by rotation of the fixing roller; First for conveying a sheet to the first fixing section
In an electrophotographic apparatus provided with a sheet transport device movably provided between a position and a second position for transporting a sheet to a second fixing section, the sheet transport device includes a sheet detection unit for detecting a sheet. An electrophotographic apparatus comprising the above-mentioned feature, wherein the movement between the first position and the second position is performed based on a sheet detecting operation by a sheet detecting unit.