JPS63264771A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the efficiency of image forming operation by stopping the operation of a paper feeding means without stopping the operation of the heating means of a heat-fixing device when no recording paper is fed to a photosensitive body from a paper feeding section. CONSTITUTION:A toner image formed on a photosensitive body 11 is thermally fixed to recording paper by means of the heating means 33 of a fixing device after the recording paper is fed to the photosensitive body 11 from a paper feeding section 16 and the toner image formed on the body 11 is transferred to the recording paper. A means which inhibits the operation of a paper feeding means 21 while the heating means 33 is operated when feeding of the recording paper is not detected by a paper feeding detecting means 42 within a prescribed time after the start of the image forming operation is instructed from an operation start instructing means, is provided. Therefore, when no recording paper is fed to the photosensitive body from the paper feeding section, the power supply to the heating means of the fixing device is not stopped and, the image forming operation can be started immediately after a prescribed paper jam restoring process. Thus the efficiency of the image forming operation can be improved sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image forming apparatus such as an electrophotographic copying machine, and in particular, the present invention relates to an image forming apparatus such as an electrophotographic copying machine. The present invention relates to an image forming apparatus that heats and fixes a recording paper using a heating means in a fixing device.

(Prior Art) In an electrophotographic copying machine, a predetermined toner image is formed on a photoreceptor drum, and recording paper fed from a paper feeder is conveyed in synchronization with the rotation of the two photoreceptor drums.

After the toner image is transferred onto the recording paper, the toner image on the recording paper is fixed by a fixing device to form a copy image. With such electrophotographic copying machines.

In order to fix a toner image on recording paper, a fixing device that uses a heating fixing method that melts and fixes the toner is common. A fixing device using a heat fixing method uses a heating roller with a heater inside as a heating means.
The toner image is fixed onto the recording paper by applying pressure to the toner image on the recording paper while the heating roller is heated to a temperature at which the toner can be melted. Therefore, in an electrophotographic copying machine employing a heat fixing method, toner cannot be fixed on the recording paper until the heating roller reaches a predetermined temperature, and copying operations cannot be performed during this time.

Furthermore, in an electrophotographic copying machine, toner images are transferred, fixed, etc. while the recording paper fed from the paper feed section is conveyed vertically across the I1 body. There is a risk of a paper jam occurring in the machine.There is a heater, charger, etc. inside the machine that is at high temperature and voltage, so do not enter the machine to remove the jammed recording paper. Inserting your hands etc. is very dangerous. For this reason, conventional electrophotographic copying machines
In the event of a paper jam, for example, the copying operation cannot be restarted unless a reset operation is performed after the power supply is once prohibited in conjunction with an operation to open the inside of the machine.

(Problems to be Solved by the Invention) Paper jams in electrophotographic copying machines occur when the recording paper is not reliably fed from the paper feed section to the photoreceptor drum, or when the recording paper wraps around the photoreceptor drum.

A possible case is that it wraps around a heating roller in a fixing device.

In any case, in conventional electrophotographic copying machines, it is necessary to perform a reset operation after power supply is once prohibited.

Therefore, the power supply to the heater of the heating roller in the fixing device is also stopped.

The temperature of the heating roller will drop. Once the temperature of the heating roller drops, the copying operation cannot be performed until the heating roller reaches a predetermined temperature, and even after the predetermined paper jam has been cleared, the user must wait for a while.

If the recording paper is not reliably fed to the photoreceptor drum,
Recording paper is not fed from the paper feed section.

Alternatively, the cause may be that the recording paper is jammed between the paper feed section and the photoconductor drum, but in either case, do not insert your hand, etc. into the high temperature or high voltage part of the two machines. Paper jams can be easily cleared without any problems. For this reason, once the power supply to the heater of the heating roller is stopped and its temperature drops once.

Even after clearing a paper jam, you have to wait.

The efficiency of copying work is significantly reduced.

The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to not stop energizing the heating means in the fixing device when recording paper is not fed from the paper feeding section to the photoreceptor; An object of the present invention is to provide an image forming apparatus which can perform an image forming operation immediately after processing a predetermined paper jam, thereby significantly improving the efficiency of the image forming operation.

(Means for solving problems).

In the present invention, recording paper is fed from a paper feeding section to a photoreceptor.

After transferring the toner image formed on the photoreceptor to recording paper,
This is an image forming apparatus that heats and fixes the toner image onto a recording paper using a heating means in a fixing device.

An operation start instructing means for instructing the start of an image forming operation, a paper feeding means for feeding recording paper from a paper feeding section to a photoconductor, and a paper feeding section for detecting the recording paper being fed from a paper feeding section to the photoconductor. If the paper feed detection means does not detect the feeding of the recording paper within a predetermined time after the instruction to start the image forming operation by the operation start instruction means, at least the paper feed is detected while the heating means is operated. and means for prohibiting the operation of the means.

This achieves the above objective.

(Example) The present invention will be described below with reference to an example of an electrophotographic copying machine.

As shown in FIG. 1, the electrophotographic copying machine of the present invention has two photosensitive drums 11 disposed approximately at the center of the machine, and copies images are formed by a normal electrophotographic process. In other words, the original on the original mounting table 12 arranged on the upper surface of body a,
While the original table 12 is moving, an electrostatic latent image is formed on the photoreceptor drum 11 by exposure by the optical system 13 and uniformly charged by the charging device 14 . Then, the latent image is developed with toner by the developing device 15, and the toner image is transferred by the transfer device 17 onto the recording paper fed from the paper feed section 6, and then the separation device 1B The toner image is separated from the photoreceptor tram 11 at the fixing bag W30, and the toner image is fixed onto the recording paper using the fixing bag W30. Residual toner is removed from the photosensitive drum 11 by a cleaning device 24 , and residual charge is removed by a static elimination lamp 25 .

Recording paper fed from the paper feed cassette 16 by one, for example, a paper feed roller 21, is once conveyed to a registration roller 22 and stopped. Then, the registration rollers 22 are rotationally driven in synchronization with the rotation of the photoreceptor drum 11, and the recording paper is fed to the photoreceptor drum 11.

The recording paper is conveyed in synchronization with the rotation of the photoreceptor drum 11 and comes into contact with the photoreceptor drum 11 as described above.

The toner image is transferred to recording paper. The recording paper onto which the toner image has been transferred is transported to a fixing device 30 by a 2wi conveyor belt 23, and the toner image is fixed to the recording paper while passing between a heating roller 31 and a pressure roller 32 in the fixing device 30. Ru. A heater 33 is disposed inside the heating roller 31 as a means for heating the heating roller 31. The heating roller 31 is heated to a predetermined temperature by the heater 33, and the heating roller 31 and the pressure roller 32 are heated. The toner on the recording paper is melted and fixed under pressure. The recording paper with the toner image fixed thereon is discharged to the outside of the machine by a paper discharge roller 26.

The fixing device 30 is provided with a thermistor 41 for detecting the surface temperature of the heating roller 31.

In addition, in this embodiment, the two machines can be divided into an upper frame body and a lower frame body, with the boundary between the transport path of the recording paper fed from the paper feed power center 16 and the upper surface of the fixing device 3°. The upper frame and the lower frame are rotatably supported at a pivot point 27 above the paper feed cassette 16.

A registration switch 42 is provided on the upstream side of the registration rollers 22 in the recording paper conveyance direction, and is a paper feed detection means for detecting the recording paper conveyed from the paper feed cassette 16 to the registration rollers 22 .

Also, at the recording paper exit in the fixing device 30.

A paper discharge switch 43 is provided as a means for detecting recording paper conveyed from the fixing device 30.

Furthermore, a safety switch 44 is provided above the paper ejection roller 24 to operate when the upper frame body is connected to the lower frame body.
is attached to the lower frame.

FIG. 2 is a schematic block diagram of a control system in an electrophotographic copying machine according to the present invention. In the figure, 350 is a control unit using a microcomputer, for example, and the control unit 5
0 includes the output of the thermistor 41 disposed in the fixing device 30, the output of the registration switch 42 that detects the recording paper fed from the paper feed cassette 16 to the registration rollers 22, and the output of the recording paper discharged from the fixing device 30. An output from a paper ejection switch 43 that detects the connection of the upper frame and a lower frame is provided, as well as an output from a safety switch 44 that detects that the upper frame and the lower frame are connected. The control unit 50 also includes an output from the main switch 45 .

On the operation panel located on the top of the aircraft. Output of the copy key 46 for instructing the start of a copying operation.

Sheet number key 47 for instructing the number of recording sheets to be copied
and an output from a clear key 48 for clearing the number of recording sheets set in the number key 47.

On the other hand, the output of the control section 50 is transmitted to the main motor 61. which is the drive source in the electrophotographic copying machine. A paper feed clutch 62 for transmitting and interrupting the power of the main motor 61 to the paper feed roller 21, which is a paper feed means for feeding recording paper from the paper feed cassette 16 to the photoreceptor drum 11. And it is applied to a heater 33 which is a heating means in the fixing device 30. Further, the control section 50 is located on an operation panel disposed on the top surface of the eight aircraft. Operation enable indicator 63 for indicating that copy operation is possible. A sheet number display 64 using a pair of 7-segment displays for displaying the number of sheets of recording paper to be fed on the operation panel. and photoreceptor drum 1
1 is provided to a paper jam indicator 65 that indicates that a paper jam has occurred on the downstream side in the recording paper conveyance direction. Note that the number-of-sheets display 64 can also indicate that a paper jam has occurred upstream of the photosensitive drum 11 in the recording paper transport direction.

When such a paper jam occurs, for example, the characters rPFJ are displayed as shown in FIG.

The operation of the electrophotographic copying machine having such a configuration will be explained based on the flowcharts shown in FIGS. 4 and 5. First, turn on the main switch 45.

The heater 33 is turned on, and the heating roller 31 is heated. Then, the surface temperature of the heating roller 31 reaches a predetermined value t°C.
When the thermistor 41 detects this, the operable indicator 63 turns on. Until the surface temperature of the heating roller 31 reaches a predetermined value t.degree. C., the operable indicator 63 remains off, and no copying operation can be performed.

In this case, if a plurality of copies of images are required, the one-sheet number key 47 is operated, and a predetermined number n is set in the recording paper sheet number counter. When the sheet number key 47 is not operated, the sheet number 1 is set in the five sheet number counter. Further, when the clear key 48 is turned on with a predetermined number of sheets set in the two-sheet counter.

The set number of sheets in the sheet number counter is reset.

The number of sheets is set to 1.

In this state, when the copy switch 46 is turned on, the paper feed clutch 62 is turned on so that it can transmit power, and the main motor 61 is driven.

As a result, the paper feed roller 21 is rotated, and the recording paper is conveyed from the paper feed cassette 16. The recording paper is stored for a predetermined time T.
During this time, it reached the registration roller 22.

Turn on the registration switch 42. As a result, it is detected that the recording paper has been conveyed from the paper feed cassette 16 to the registration rollers 22.

On the other hand, also due to the rotation of the paper feed roller 21.

When the recording paper is not fed from the paper feed cassette 16.

Alternatively, if the recording paper is stuck between the paper feed roller 21 and the registration roller 22, the recording paper does not reach the registration roller 22 within the predetermined time T. and.

If the registration switch 42 is not turned on within the predetermined time T, it is assumed that a paper jam has occurred between the paper feed cassette 16 and the photosensitive drum 11, and the control unit 50 sets the paper feed clutch 62 to the power cutoff state. The rPF is turned off and the nine-sheet count display 64 indicates that the paper jam has occurred.
Display the letter J. and.

Ready indicator 63 is turned off. In this case, heater 3
3 is not stopped, and the surface of the heating roller 31 is maintained at a predetermined temperature. In this case, if the drive of the main motor 61 is not stopped, the photosensitive drum 11. Conveyor belt 23. Since the fixing device 30 and the like are driven, when a paper jam occurs between the paper feed cassette 16 and the registration roller 22 during continuous copying, the recording paper is placed downstream of the photosensitive drum 11 in the recording paper transport path. If there is, the recording paper is ejected from the machine.

When the characters rPFJ are displayed on the sheet count display 64, the operator who was operating the copying machine can

It is recognized that a paper jam has occurred between the paper feed cassette 16 and the registration switch 22, and predetermined paper jam handling is performed. For example, this process may occur because the paper feed cassette 16 is not securely attached to the machine.

Alternatively, if the recording paper is not fed from the paper cassette 16 due to the paper being fed in the cassette 16 even though it is present in the cassette 16, the paper cassette 16 must be securely attached to the machine, or , place the recording paper in a predetermined position in the paper feed cassette 16, and if a paper jam occurs between the paper feed roller 21 and registration roller 22, remove the paper feed cassette 16 and remove the jammed record. Remove paper.

After clearing the paper jam, turning on the copy switch 46 turns off the rPFJ display on the 9-sheet count display 64, and as the heater 33 continues to be energized, the machine immediately becomes ready for operation. The ready indicator 63 is turned on. Then, the paper feed clutch 62 is turned on, and the recording paper is fed from the paper feed cassette 16 to the registration rollers 22.

Also, during continuous copying, there is no need for a copying operation after a predetermined paper jam has been cleared.

When the clear key 48 is operated, the display of rPFJ on the one-sheet number display 64 is turned off, and one aircraft enters a standby state.

When the registration switch 42 detects that the recording paper has reached the registration roller 22, the registration roller 22 is rotated in synchronization with the photoreceptor drum 11, and so on.

Similar to a conventional electrophotographic copying machine, the toner image is transferred onto the recording paper, the recording paper is separated from the photosensitive drum 11, and so on, and the toner image is transferred onto the recording paper.

The recording paper onto which the toner image has been transferred is conveyed by a conveyor belt 23 and fed to a fixing device 30, where the toner image is fixed onto the recording paper by a heating roller 31 heated to a predetermined temperature. The recording paper with the toner image fixed on it.

After the paper ejection switch 43 is turned on, the paper is ejected from the machine by the paper ejection roller 24.

When the paper ejection switch 43 is turned on, the set number of sheets in the two-sheet counter is decremented by one when a predetermined number of sheets are continuously copied, and if the set number of sheets is not O, the paper feed clutch 62 is turned on. The recording paper is placed on the photoreceptor drum 11 again.
A predetermined copying operation is repeated. When a predetermined number of copies are completed, the main motor 61 is stopped and the two machines enter a standby state in which the heater 33 is continuously energized for 41 days. In this case, the operable indicator 63 continues to be on. Then, when the main switch 45 is turned off, the heater 33
At the same time, the operation ready indicator 63 is turned off.

During such a copying operation, a predetermined transfer is performed.

If the paper ejection switch 43 is not turned on after the separation and fixing operations are completed, it is assumed that the recording paper is jammed on the downstream side of the photosensitive drum 11 in the recording paper conveyance direction, and the control unit 5
0 turns off the operable indicator 63, turns on the 1 paper jam indicator 65, and also stops driving the main motor 61 and stops energizing the heater 33 of the heating roller 31. As a result, the worker who was operating the copying machine recognizes that the recording paper is jammed on the downstream side of the photosensitive drum 11 in the recording paper conveyance direction, and separates the upper frame from the lower frame. Remove the recording paper present in the recording paper transport path. In this case, by stopping the power supply to the heater 33, the temperature of the heating roller 31 is lowered, and
This is because the rotation of the photoreceptor drum 11 and the like is stopped.

Workers can safely remove jammed recording paper. When the upper frame is separated from the lower frame.

The safety switch 44 is turned off, and when the upper frame is connected to the lower frame after removing the recording paper, the safety switch 44 is turned on, the 1 paper jam indicator 65 is turned off, and the heater 33 is turned off. The power supply is restarted, and the heating roller 31 is heated. When the surface of the heating roller 31 reaches a predetermined temperature, the operable display 63 is turned on and the two machines enter a standby state, and when the copy switch 46 is turned on, the copying operation is performed as described above.

When such a paper jam occurs during continuous copying, if there is no need to continue the copying operation after processing one paper jam, a clear key 48 is operated to clear the set number of sheets in the one-sheet counter and enter a standby state.

(Effects of the Invention) As described above, in the image forming apparatus of the present invention, when the recording paper is not fed from the paper feeding section to the photoreceptor, at least the recording paper is fed without stopping the operation of the heating means in the heat fixing device. Since it stops the operation of the paper means, even if a jam occurs between the paper feed section and the photoreceptor, the image forming operation can be performed immediately after the predetermined processing is completed.2 The efficiency of image forming operation is improved. Significantly improved.

4. Figure 1 is a sectional view of an electrophotographic copying machine showing an example of the present invention.
FIG. 2 is a schematic block diagram of the control system.

FIG. 3 is an explanatory diagram showing an example of a paper jam display on the sheet number display, and FIGS. 4 and 5 are respectively.

3 is a flowchart for explaining the operation of the electrophotographic copying machine of the present invention.

11... Photosensitive drum, 16... Paper feed cassette, 2
1... Paper feed roller, 22... Registration roller, 30
...Fixing device.

33... Heater, 41... Thermistor, 42...
Registration switch, 43... Paper ejection switch, 44...
・Safety switch, 46...Copy switch, 50...
-Control unit, 61...Main motor, 62...Paper feed clutch.

that's all

Claims (1)

[Scope of Claims] After the recording paper is fed from the paper feeding section to the photoreceptor and the toner image formed on the photoreceptor is transferred to the recording paper, the toner image is heated onto the recording paper by a heating means in a fixing device. It is an image forming apparatus for fixing, and includes an operation start instructing means for instructing the start of an image forming operation, a paper feeding means for feeding recording paper from a paper feeding section to a photoconductor, and a paper feeding section for feeding recording paper from a paper feeding section to a photoconductor. a paper feed detection means for detecting the recording paper that is being fed; An image forming apparatus comprising: means for prohibiting at least the operation of the paper feeding means while operating the paper feeding means.