JPH05289563A - Fixing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To eliminate waste of copying sheet due to delay in detection of jamming and to reduce maintenance cost in a copying machine by individually setting jamming detection timing corresponding to each copying mode. CONSTITUTION:Heating lamps 35 to 37 where heating temperature of each can be controlled to an arbitrary temperature, are provided in a central part of fixing rolls 32 to 34 and outer periphery surface of each fixing roll 32 to 34 is heated by these heating lamps 35 to 37 and color toner transferred to a copying sheet 41 is melt-stuck by being heated by heater lamps 35 to 37. Moreover, the fixing rolls 32 to 34 have the rotational direction and positions of the rolls appropriately changed over for each copying mode. A different fixing roll among 32 to 34 is utilized for a full color copying mode, a color copying mode, or a black and white copying mode and the length of the fixing and carrying path is different for each copying mode. Then, since the jamming detection time is made different according to each copying mode in the fixing device 22, a more accurate jamming detection can be carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner on a copy sheet by heating and melting the toner image transferred to the copy sheet in an electrophotographic apparatus such as a full color copying machine. is there.

[0002]

2. Description of the Related Art A full-color copying machine, which is an electrophotographic apparatus, is usually capable of executing a color copying mode for copying with a single color toner and a full-color copying mode for copying with a plurality of color toners. When copying with, the color images of yellow, magenta, and cyan are transferred onto the copy sheet, and the multi-layer image formed by stacking these color toners is fixed on the copy sheet, so that the original image It is possible to obtain a full-color copy image that faithfully reproduces the color of.

As described above, when copying is performed by the full-color copying machine, for example, a jam occurs when the copy sheet is not conveyed at a predetermined timing by the fixing device, or slips or is caught during fixing. Sometimes. Normally, the fixing device 22 includes a sheet detection sensor 5 provided in the conveyor belt 21 and a sheet detection sensor 6 for detecting the copy sheet after fixing, as shown in FIG. 4 which is an explanatory view of the present invention. Is provided. The fixing passage time of the copy sheet is calculated from the detection signals from the sheet detection sensors 5 and 6, and the fixing device 22 detects the jam by comparing the fixing passage time with the preset jam detection time.

Copy sheet 4 in the fixing device 22
The fixing of No. 1 will be described for each copy mode with reference to FIG.

First, in the full-color copying mode, the transferred copy sheet 41 is fixed by the fixing belt 32.
The toner is fixed while being conveyed to the nip 38 of 33 and being heated and pressed there, and the copy sheet 41 is pushed out to the carry-out port 40. At this time, the leading edge of the copy sheet 41 conveyed from the transfer section is detected by the sheet detection sensor 5 on the conveyance belt 21. Then, the copy sheet 41 on which the toner has been fixed is fed to the paper detection sensor 6 immediately before the exit 40.
The tip portion is detected by. In this way, the fixing passage time of the copy sheet 41 is calculated.

Next, in the black-and-white copy mode, the transferred copy sheet 41 is conveyed by the conveyor belt 21 which is not inclined.
The copy sheet 4 is conveyed to the nip 39 of the fixing rollers 33 and 34, where the toner is fixed while being heated and pressed.
1 is pushed out to the carry-out port 40. At this time, the copy sheet 41 conveyed from the transfer section has its leading end detected by the sheet detection sensor 5 on the conveyance belt 21 as in the case of full-color copying, and the toner sheet-fixed copy sheet 41 is taken out. Immediately before 40, the leading edge of the sheet is detected by the sheet detection sensor 6. In this way, the fixing passage time of the copy sheet 41 is calculated.

Jam detection in the fixing device in each of the copying modes will be described. In the case of full-color mode copying, the above-described fixing passage time is calculated, and the fixing passage time and the preset jam detection time are calculated. According to the comparison, when the fixing time is longer than the jam detection time, the copying operation is stopped. Also in the color copying mode or the black-and-white copying mode, the copying operation is stopped when the fixing time is longer than the jam detection time, as in the full-color copying mode.

[0008]

In a full-color copying machine in which the fixing roller is switched depending on the copying mode, the fixing conveyance path length of the copy sheet, that is, the sheet detection sensor provided in the conveyance belt is used to detect the fixing roller depending on each copying mode. The length to the paper detection sensor that detects the fixed copy sheet via the nip between them is different. Further, in the full-color copying mode and the color copying mode or the black-and-white copying mode, the toner adhesion amount is different and the fixing time is also different. Therefore, the fixing passage time and the jam detection time in each copy mode are different.

However, in the conventional full-color copying machine, the jam detection is performed in the fixing device by setting the same jam detection time regardless of the copy mode. Therefore, it is not possible to perform accurate jam detection in each copy mode, and the jam detection during fixing is delayed. Due to the delay in the jam detection, the copy sheets are wasted, and the jam cannot be detected early, which causes a trouble of the copying machine and raises the maintenance cost and maintenance cost of the copying machine.

The present invention has been made in view of the above problems, and an object of the present invention is to perform more accurate jam detection by separately setting the jam detection time corresponding to each copy mode. Accordingly, it is an object of the present invention to provide a fixing device for an electrophotographic apparatus that eliminates waste of copy sheets due to delay in jam detection and reduces maintenance costs in a copying machine.

[0011]

The fixing device of the electrophotographic apparatus according to the present invention uses different fixing rollers depending on the full-color copying mode and the color copying mode or the black-and-white copying mode. Therefore, the fixing conveyance path length is different in each copying mode. In a fixing device of an electrophotographic apparatus such as a full-color copying machine, the jam detection time in the fixing device is changed according to each copying mode.

[0012]

With the above construction, by changing the jam detection time in the fixing device according to each copy mode, the jam detection time can be set in advance for each copy mode. By comparing the calculated fixing passage time with the jam detection time selected according to the copy mode at that time, more accurate jam detection can be performed. Therefore, it is possible to reduce the waste of the copy sheet due to the delay of the jam detection and reduce the maintenance cost in the copying machine.

[0013]

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

The fixing device of the electrophotographic apparatus according to the present embodiment, as shown in FIG. 3, has a color copy mode and a monochrome copy mode for copying an original image in a single color, and faithfully reproduces the original image color for copying. It is built into a full-color copying machine which is an electrophotographic apparatus capable of executing the full-color copying mode.

The above-mentioned full-color copying machine has a transparent original placing table 11 on its upper surface, and an original 23 to be copied is placed on the original placing table 11. Below the document table 11, the exposure optical system 12 is provided.
The exposure optical system 12 includes an exposure lamp 12a that irradiates a document 23 placed on the document table 11 with light and a light reflected from the document 23 that is exposed by a broken line, for example. It is provided with a plurality of reflecting mirrors 12b ... Which are guided onto the body 17, an imaging lens 12c arranged on the optical path, and a color separation filter 12d having color filters of three primary colors of red, green, and blue.

Below the exposure optical system 12, a photoconductor 17 to which the above-mentioned reflected light is irradiated is arranged. The photoconductor 17 is in the form of a belt, and is a roller 2 for rotational driving.
It is stretched on April 25. Further, between the photoconductor 17 and the exposure optical system 12, a black and white developing tank 13 and color developing tanks 14 to 16 are disposed in a state of not contacting the photoconductor 17, and the color developing tanks 14 to 16 are provided. Each of the developing tanks 14 to 16 contains a color developer composed of yellow, magenta, and cyan color toners and a carrier, respectively.

A charger (not shown) that charges the photoreceptor 17 and a cleaning device (not shown) that removes the toner remaining on the photoreceptor 17 are provided on the roller 24 side of the outer periphery of the photoreceptor 17. There is. Below the charger and the cleaning device, there are provided a manual paper feed tray 27 and two paper feed cassettes 18 and 19 for each paper size. The paper cassettes 18 and 19 send out copy sheets to the transport system 26.

On the other hand, on the roller 25 side of the photoconductor 17, an intermediate transfer body 20 pressed against the photoconductor 17 is arranged. The intermediate transfer body 20 is in the form of a belt and is a roller for rotation drive. It is stretched at 28-30. The intermediate transfer body 20 is sandwiched between the roller 30 and a transfer roller 31 arranged so as to face the roller 30, and the intermediate transfer body 20 is provided between the transfer roller 31 and the intermediate transfer body 20. Copy sheets sent from the paper tray 27 or the paper feed cassettes 18 and 19 are carried in via the transport system 26.

The transfer roller 31 and the intermediate transfer member 2 described above.
A transport belt 21 that transports the copy sheet onto which the color toner is transferred from the intermediate transfer body 20 is disposed on the unloading side of 0, and the color toner is heated and melted on the unloading side of the transport belt 21. A fixing device 22 for fixing the copy sheet is provided.

As shown in FIG. 4, the fixing device 22 comprises a conveyor belt 21 for conveying a copy sheet 41 on which color toner has been transferred, and three fixing rollers 32 to 34 which are vertically connected to each other. Paper detection sensors 5 and 6 for detecting the passage of the copy sheet 41 are provided in the conveyance belt 21 and near the fixing rollers 32 to 34 unloading outlets.

The fixing rollers 32 to 34 each have a heater lamp 35 to which the heat generation temperature can be controlled to an arbitrary temperature.
37 is provided in the center, and these heater lamps 3
Reference numerals 5 to 37 heat the outer peripheral surfaces of the respective fixing rollers 33 to 34 to heat and melt the color toner transferred to the copy sheet 41. Further, the fixing rollers 32 to 34 are configured such that the rotation direction and the positions of the rollers are appropriately switched depending on each copy mode.

The sheet detection sensors 5 and 6 are provided to calculate the time when the copy sheet 41 passes through the fixing device 22, that is, the fixing passage time. The fixing passage time and the preset jam detection time are calculated. Jam detection of the fixing device is performed by comparison with.

As shown in FIG. 2, the above-mentioned control means is an I / O serving as a buffer circuit for control signals of the paper detection sensors 5 and 6, the conveyor belt drive system 7 and the fixing roller drive system 8.
It is composed of a circuit 4, a ROM 2, a RAM 3, and a CPU 1 connected to each of the above circuits and the like by a data bus and an address bus.

The ROM 2 connected to the CPU 1 stores various programs necessary for fixing such as conveyance belt drive control and fixing roller drive control, relational expressions for calculating jam detection time, and the like. Further, a jam detection time required for a jam detection described later is written in the RAM 3 connected to the CPU 1.

The fixing device 22 is disclosed in Japanese Patent Laid-Open No. 51-98.
As disclosed in Japanese Patent No. 036, the conveyor belt 21
Between the fixing rollers 32 and 33, that is, the nip 38
And the fixing rollers 33 and 34, that is, the nip 39.
Further, the copy sheet 41 on which the toner has been transferred can be switched and conveyed.

The operation of the fixing device 22 of the present embodiment having the above structure will be described.

First, when performing full-color copying in the full-color copying mode, as shown in FIG.
Light is emitted from the light source lamp 12a to the original document 23 placed on the document, and scanning is performed. The reflected light of the original 23 is reflected by the reflecting mirrors 12b ... And the imaging lens 12.
After being incident on the color separation filter 12d via c, the color separation filter 12d separates each color component, the reflecting mirror 1
The photoconductor 17 is irradiated via 2b.

The above scanning is repeated three times for each color component, and the light for each color component transmitted through each color filter of the color separation filter 12d is exposed uniformly by a charger (not shown). The body 17 is irradiated with light in order, and an electrostatic latent image for each color component on the original 23 is formed on the photoconductor 17.

At this time, each of the electrostatic latent images described above is formed at a portion facing the developing tanks 14 to 16 having developers of respective colors of yellow, magenta, and cyan which are complementary colors of the respective color filters in the color separation filter 12d. The toner image is developed by each developer supplied from a developing magnet roller provided in each developing tank (not shown), and the toner image for each color component is transferred to a corresponding portion of the intermediate transfer body 20. From this, at the end of three scans, the toner images for the respective color components are overlaid on the intermediate transfer body 20,
One completed toner image is formed.

The toner image is transferred by the transfer roller 31 to the copy sheet supplied from the paper feed tray 27 or the paper feed cassettes 18 and 19 through the transport system 26.
After that, the copy sheet onto which the toner image has been transferred is separated from the intermediate transfer body 20 and introduced into the fixing device 22 by the transport belt 21.

On the other hand, when a single-color copy is made in the color copy mode and the black-and-white copy mode, the light source lamp 12a irradiates the original 23 on the original table 11 with light.
The scan will be performed once. The reflected light from the original 23 by this scanning is guided to the photoconductor 17 by the reflecting mirrors 12b ... And the imaging lens 12c, and an electrostatic latent image for the original 23 is formed on the photoconductor 17. Then, the electrostatic latent image formed on the photoconductor 17 is developed with a black developer in the developing tank 13 or one of the developing tanks 14 to 16 to be a toner image. After that, this toner image is transferred to the intermediate transfer member 20, and further transferred to the copy sheet by the transfer roller 31,
The copy sheet onto which the toner image has been transferred is introduced into the fixing device 22 by the conveyor belt 21.

As shown in FIG. 4, the copy sheet introduced into the fixing device 22 in each of the above-mentioned copying modes has the leading end of the conveyor belt 21 in the full-color copying mode by a control device such as a solenoid (not shown). The nip 3 between the fixing rollers 32 and 33 rises to the position shown by the dotted line.
It is heated and pressed at 8. Further, in the color copying mode or the black-and-white copying mode, the conveyor belt 21 is in a state where it does not rise as shown by the solid line, and the copy sheet is heated and pressed by the nip 39 between the fixing rollers 33 and 34. At this time, the leading edge of the copy sheet passing through the conveyor belt 21 is detected by the paper detection sensor 5 provided in the conveyor belt 21, and the leading edge of the copy sheet passing through the nip 38 or the nip 39 is detected by the paper detection sensor 6. Detected. Based on the detection results of the sheet detection sensors 5 and 6, the time taken for the copy sheet to pass from the sheet detection sensor 5 to the sheet detection sensor 6 via the nip 38 or the nip 39,
That is, the fixing passage time is calculated.

As described above, the reason for using different fixing rollers depending on the copy mode is that the fixing conditions in each copy mode, that is, the fixing time or the fixing temperature, are different. For example, in the case of the full-color copy mode, since the toner is multi-layered in order to faithfully reproduce the original image as described above, the toner adhesion amount becomes larger than that in other copy modes, and the fixing time is extended or the fixing temperature is increased. Appropriate fixation is performed by raising the. Since the fixing conditions differ depending on the copy mode as described above, if the same fixing roller is shared and used in each copy mode, it becomes difficult to perform appropriate fixing for each copy mode. Therefore, in order to perform fixing that satisfies different fixing conditions for each copy mode, it is necessary to use a fixing device provided with different fixing rollers that can be switched for each copy mode as in the present embodiment. ..

Further, in the fixing device 22, when the timing of sending the copy sheet from the fixing rollers 32 and 33 or the fixing rollers 33 and 34 is delayed, or when the copy sheet is slipped midway and predetermined fixing is not performed. Jam occurs. Therefore, when such trouble occurs, jam detection for stopping the copying machine is performed. Therefore, the jam detection in the fixing device 22 is performed by comparing the fixing passage time calculated by the paper detection sensors 5 and 6 with the preset jam detection time.

Jam detection in the fixing device 22 will be described with reference to the flowchart of FIG.

First, copying is performed by starting copying. At this time, it is selected whether or not it is the full-color copy mode (S1). In the full-color copying mode, the fixing conveyance path length, that is, the length from the sheet detection sensor 5 shown in FIG. 4 to the sheet detection sensor 6 via the nip 38 is recognized (S2). The passage time is obtained from the fixing conveyance path length and the conveyance speed using a relational expression programmed in advance in the ROM 2, and the passage time is set as the jam detection time t1 (S3). On the other hand, in the color copy mode or the black-and-white copy mode, the fixing conveyance path length, that is, the length from the sheet detection sensor 5 to the sheet detection sensor 6 via the nip 39 is recognized (S4). The passage time is calculated from the fixing conveyance path length and the conveyance speed using a relational expression programmed in advance in the ROM 2, and the passage time is set as the jam detection time t2 (S5). Then, the jam detection times t1 and t2 obtained above are written in the RAM 3 described above (S6).

Next, when a copy sheet passes through the paper detection sensor 5 and the paper detection sensor 6 during copying, a signal is sent from the paper detection sensors 5 and 6 to the CPU 1 via the I / O circuit and stored in the ROM 2. The fixing passage time of the copy sheet is calculated by the obtained passage time calculation formula. Further, the data regarding the jam detection time of each copy mode which is written in the RAM 3 in advance is selected and sent to the CPU 1, and the jam is determined by comparing with the fixing passage time (S7). If no jam is detected, it is determined whether copying is completed (S11), and if a jam is detected, CP is determined.
An operation stop signal is sent from U1 to each drive system such as the conveyor belt drive system 7 and the fixing roller drive system 8 to stop the copying operation (S8). Next, it is determined whether the jam processing is completed (S9). When the jam processing is completed, the copying operation is restarted (S10). If the jam processing is not completed, the copying operation remains stopped. Then, it is determined whether or not copying is completed (S11). At this time, if the end of copying is detected, the execution of copying is ended. If the end of copying is not detected, copying is continued.

In this way, by setting the jam detection in the fixing device 22 by changing the jam detection time depending on each copy mode, the fixing passage time calculated from the fixing conveyance path length in a certain copy mode and the time By comparing the jam detection time selected in the copy mode of
It is possible to perform more accurate jam detection. Therefore, it is possible to reduce the waste of the copy sheet due to the delay of the jam detection, and it is possible to reduce the maintenance cost and the maintenance cost of the copying machine.

[0039]

As described above, the fixing device of the electrophotographic apparatus of the present invention has different fixing rollers depending on the full-color copying mode and the color copying mode or the black-and-white copying mode. In a fixing device of an electrophotographic apparatus such as a full-color copying machine having a different length, a jam detection time in the fixing device is changed according to each copying mode.

Therefore, by setting the jam detection time corresponding to each copy mode, the jam detection in each copy mode can be accurately performed, and the waste of copy sheets due to the delay of the jam detection can be reduced. It is possible to reduce the maintenance cost and the maintenance cost of the copying machine.

[Brief description of drawings]

FIG. 1 is a flowchart of jam detection control in a fixing device of an electrophotographic apparatus of the present invention.

FIG. 2 is a block diagram of control means in a full-color copying machine.

FIG. 3 is a front view showing a schematic configuration of a full-color copying machine of this embodiment.

FIG. 4 is a schematic view of a fixing device of the full-color copying machine in FIG.

[Explanation of symbols]

 32-34 fixing roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location G03G 15/20 107 (72) Inventor Nobuyuki Ueda 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Within the corporation

Claims (1)

[Claims] 1. A fixing device for an electrophotographic apparatus, such as a full-color copying machine, which uses different fixing rollers depending on a full-color copying mode and a color copying mode or a black-and-white copying mode. A fixing device for an electrophotographic apparatus, wherein the jam detection time in the fixing device is changed according to each copy mode.