JPH09134097A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely move an image forming body by releasing the pressure- contact of a transfer means, in case a jam occurs during image transfer. SOLUTION: A mechanism brings the transfer roller 18 into pressure-contact with the periphery of a photoreceptive drum 10 and releases its pressure-contact by the turn of a pressing member 80 which is in pressure contact with a cam C on a cam plate 70 which is rotated by a pulse motor M. The timing of image transfer is detected by the signal of a photosensor S which detects each notch of the cam plate 70. In case an abnormal condition occurs during the transfer, all the driving systems of the device are stopped, thereafter only the drive of the pulse motor M is resumed to release the pressure contact of the transfer roller 18, and the cam plate 70 is set into a home position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a charging means, an image exposing means and a developing means arranged around an image forming body, and a toner image is formed on the peripheral surface of the image forming body by rotating the image forming body. The present invention relates to an image forming apparatus using an electrophotographic system for transferring a sheet onto a transfer material by a transfer device of a pressure type.

[0002]

2. Description of the Related Art Among image forming apparatuses, an electrophotographic copying machine used for office work or an image recording apparatus used as a terminal device can easily perform maintenance work such as jam clearance, inspection and replacement of equipment. For this purpose, a structure is adopted in which the transfer material transport surface can be opened on the user side.

As for the structure of such an apparatus, a conventional apparatus main body is divided into upper and lower parts with a transfer material conveying surface as a boundary, and an upper main body for accommodating an image forming body is opened and closed vertically with respect to a lower main body for accommodating a transfer means. In the so-called clamshell type device, the main body of the device is divided into a first main body and a second main body, and the second main body containing the image forming body is moved horizontally with respect to the first main body containing the transfer means. There are known devices for doing so.

[0004]

However, the occurrence of the transfer material transport accident is high when the toner image is transferred,
In that case, when the transfer means is pressed against the image forming surface and the image forming body is moved from the pressed state, there is a risk that the image forming surface is damaged due to rubbing of the transfer means.

As a result of solving and improving this point, the present invention provides
An object of the present invention is to provide an image forming apparatus that stops the rotational operation of the image forming body and releases the pressure-bonding action of the transfer unit on the image forming surface when an abnormality occurs in the conveyance of the transfer material.

[0006]

The above-mentioned object is to provide an image forming body, a charging means for charging the image forming body, an image exposing means for performing image exposure on the image forming body, and the image forming means. Developing means for developing the latent image formed on the body into a toner image, transfer means for transferring the toner image onto a transfer material, and fixing for fixing the transferred toner image onto the transfer material. In the image forming apparatus including means, the apparatus is configured by a first main body including at least the transfer means, and a second main body including at least the image forming body that is attachable to and detachable from the first main body in a substantially horizontal direction, This is achieved by an image forming apparatus characterized by further comprising control means for stopping the operation of the main drive system including the image forming body to release the pressure-bonding action of the transfer means with respect to the image forming body when an abnormality occurs.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to a color image forming apparatus shown in FIGS.

In FIG. 1, reference numeral 10 designates a photosensitive drum which is an image forming body, which is formed by coating an OPC photosensitive body on the drum and is grounded and driven and rotated clockwise. 12 is a scorotron charger, provided by a corona discharge by a grid and the corona discharge wire which uniform charging has been potential held in the V _G of the V _H the photosensitive drum 10 peripheral surface. Prior to the charging by the scorotron charger 12, in order to eliminate the history of the photoconductor up to the previous print, exposure is performed by the PCL 11 using a light emitting diode or the like to eliminate the charge on the peripheral surface of the photoconductor.

Image exposure means 13 after uniform charging of the photoreceptor
Performs image exposure based on the image signal. The image exposure means 13 scans the optical path by a reflecting mirror 132 through a rotating polygon mirror 131, an fθ lens, and the like, using a laser diode (not shown) as a light emitting light source. The rotation of the photosensitive drum 10 (sub-scanning) A latent image is formed. In this embodiment, the character portion is exposed to form a reversal latent image such that the character portion has a lower potential _VL .

At the periphery of the photosensitive drum 10, there are provided developing units 14 each containing a developer composed of toner such as yellow (Y), magenta (M), cyan (C), black (K) and a carrier. First, the development of the first color is performed by the developing sleeve 141 which contains a magnet and holds the developer and rotates. The developer consists of a carrier in which ferrite is used as a core and is coated with an insulating resin around it, and a toner whose main component is polyester and pigments according to the color and charge control agents, silica, titanium oxide, etc. are added. The agent is regulated by the layer forming means to have a layer thickness (developer) of 100 to 600 μm on the developing sleeve 141 and is conveyed to the developing area.

[0011] As 0.2~1.0mm gap is greater than the layer thickness (developer) to the developing sleeve 141 in the developing zone between the photosensitive drum 10, the DC bias of the AC bias and V _DC of V _AC during which The signals are superimposed and applied. V _DC and V _H, for charging the toner are the same polarity, the toner given the opportunity to leave from the carrier by V _AC and V
_It does not adhere to the _VH portion having a higher potential than _DC, but adheres to the _VL portion having a lower potential than _VDC , and visualization (reversal development) is performed.

After the visualization of the first color is completed, the process proceeds to the image forming process of the second color, the uniform charging is performed again by the scorotron charger 12, and a latent image based on the image data of the second color is formed by the image exposing means 13. To be done. At this time, the charge elimination by the PCL 11 performed in the image forming process of the first color is not performed because the toner attached to the image portion of the first color scatters due to the sudden decrease in the potential around the image.

Again, a latent image similar to that of the first color is formed on the portion of the photoconductor having the potential of V _H all over the peripheral surface of the photoconductor drum without the image of the first color, and development is performed. However, in the portion where the first-color image is developed again, the latent image of V _M ′ is formed by the light-shielding toner of the first color and the electric charge of the toner itself.
Developing in response to the potential difference between the _DC and V _M 'is performed. In the overlapping portion of the first color image and the second color image, development of the first color is performed by V
_When the latent image of _L is formed, the balance between the first color and the second color is lost, so that the exposure amount of the first color is reduced and V _H > V _M >
In some cases, the intermediate potential may be V _L.

For the third and fourth colors, the same image forming process as that for the second color is performed, and 4 steps are performed on the peripheral surface of the photosensitive drum 10.
A visible color image is formed.

On the other hand, the half-moon roller 16 from the paper feeding cassette 15
The recording paper P carried out via the printer is temporarily stopped, and is supplied to the transfer area by the rotation of the paper supply roller 17 when the transfer timing is adjusted.

In the transfer area, a transfer roller 18 is pressed against the peripheral surface of the photosensitive drum 10 in synchronism with the transfer timing, and the supplied recording paper P is nipped and a multicolor image is transferred at once. It

Then, the recording paper P is de-charged by the pointed electrodes 19 provided with a slight gap, and the photosensitive drum 10 is discharged.
The toner is conveyed to the fixing device 20 after being separated by the peripheral surface of the heat roller 201, and the toner is welded by heating and pressing of the heat roller 201 and the pressure roller 202, and then discharged to the outside of the device via the paper discharge roller 21. The transfer roller 18 is retracted from the peripheral surface of the photosensitive drum 10 after the recording paper P has passed, and is ready for the formation of the next toner image.

On the other hand, the photosensitive drum 10 from which the recording paper P is separated
Removes and cleans the residual toner by pressing the blade 221 of the cleaning device 22 and receives the charge removal by the PCL 11 and the charge by the charger 12 again to start the next image forming process. The blade 221 moves immediately after the cleaning of the surface of the photoconductor and is retracted from the peripheral surface of the photoconductor drum 10.

The transfer roller 18 is pressed and released from the peripheral surface of the photosensitive drum 10 by the driving mechanism shown in FIGS. 2 and 3 and the operation time charts and operation flows shown in FIGS. 4 and 5. It

The pulse motor M rotates clockwise when the image is not formed, so that the gear G3 on the motor shaft is rotated.
0 also rotates the sun gear G33 clockwise through the gear G31 and the coaxial gear G32, and revolves the planetary gear G34 on the rotatable support plate 66 clockwise as shown in FIG. Is operated, and an operation such as color selection of toner to be supplied to the developing device 14 is performed as necessary.

The pulse motor M rotates counterclockwise with the start of image formation, revolves the planetary gear G34 counterclockwise as shown in FIG. 3, and connects the transfer roller 18 to the pressure contact drive. The gear G40 is rotated counterclockwise.

The gear G40 is a coaxial integral gear G4.
From 1 through the gear G42, the power to rotate counterclockwise is transmitted to the gear G43 with which the cam plate 70 is integrated.

The cam plate 70 is integrally formed with a cylindrical cam C having two large and small radii of curvature R and r, and a notch corresponding to the fixed photosensor S at the position divided into four equal parts on the outer peripheral edge thereof. 70A, 70B, 70C and 70D and 70
E is equipped.

A pressing member 80, which is bent in a U-shape and rotates around a shaft 80A as a fulcrum, presses the tip 80B of the cam C by the urging force of a tension spring 81, and further the pressing member 80 is pressed. A pressure contact lever 90 for supporting the transfer roller 18 presses a protrusion 92 against the pressure pin 82 provided by the protrusion 92 by the urging force of a tension spring 91.

In the cam plate 70, as shown in FIG. 2, the angle at which the notch 70A is detected by the photosensor S is the home position (HP) of rotation, and the cam C has a large curvature at this angle. The tip portion 80B of the pressing member 80 is pressed against the radius R. Therefore, the pressing member 8
0 occupies the position rotated counterclockwise, and the pressing pin 82 presses the projection 91 of the pressing lever 90 to press the pressing lever 90.
Is placed at a position rotated clockwise about the shaft 90A as a fulcrum, whereby the transfer roller 18 is retracted to a position separated from the peripheral surface of the photosensitive drum 10 at the home position (HP).

When the pulse motor M rotates in the counterclockwise direction, the cam C rotates as shown in FIG. 3 to press the tip portion 80B of the pressing member 80 against a portion having a small radius of curvature r. The member 80 occupies a position rotated clockwise, and the pressing pin 82 is separated from the projection 92 of the pressure contact lever 90 to free the pressure contact lever 90, whereby the transfer roller 18 is urged by the tension spring 91 and the photosensitive drum 10 is urged. The transfer action of the image is started by pressing it against the peripheral surface of.

The rotation speed of the pulse motor M is controlled by a detection signal generated by the photosensor S sequentially detecting each notch of the cam plate 70 as shown in FIG. 4, and the pressure contact state of the transfer roller 18 is maintained. And two notches 7
After continuously detecting 0D and 70E, the transfer roller 18
The pressure contact is released and stopped again at the position where the notch 70A is detected, and the cam C is again set to the initial position shown in FIG. 3, that is, the home position described above.

Further, this apparatus is provided with a detecting means (not shown) for detecting a jam-related conveyance abnormality related to the recording paper P, and the transfer of the image from when the notch 70B is detected to when the notch 70E is detected. When the above-mentioned abnormal situation is detected in the middle, that is, while the transfer roller 18 is pressed against the peripheral surface of the photoconductor drum 10, the program incorporated in the control circuit of the drive system causes the drive system to follow the flow shown in FIG. The task of abnormal stop is performed.

That is, when the occurrence of an abnormal situation is detected and the image forming program is switched to the abnormal stop task program, the main motor is turned off and the drive system of the apparatus is stopped. The operation of the motor M is also temporarily stopped.

After the main motor is turned off, the photosensitive drum 10 and others are kept stationary for a predetermined time, for example, 100 ms, and then only the pulse motor M is driven again to rotate the cam plate 70. When the transfer roller 18 is restarted, the transfer roller 18 is released from the pressure contact with the peripheral surface of the photosensitive drum 10, and the rotation operation of the pulse motor M is stopped by detecting the home position described above, and the transfer roller 18 is retracted from the peripheral surface of the photosensitive drum 10. Keep it in the correct position.

As a result, the photosensitive drum 10 can be safely moved and pulled out without any obstacle in the horizontal direction, and maintenance such as jam removal can be carried out.

Horizontal movement of the photosensitive drum 10, etc.,
For example, a detaching function as described below is used for the drawer.

FIG. 6 shows the layout of the planes of the respective units constituting the apparatus. The side indicated by the arrow A corresponds to the front surface of the apparatus, that is, the side surface on the operating side.

The main body of the apparatus is composed of two upright side panels 1.
And a side panel 2, and a writing unit which is the image exposing means 13 between these side panels, a photosensitive drum 10, a developing unit which houses a plurality of developing devices 14, and a fixing device. 20 units and a DC power supply unit are incorporated, while a drive system, a formatter for decoding printer commands, and control boards for machine operation sequence control are housed outside the side panel 1, and the upper part of the developing unit. Each developing unit 1 in the developing unit
The toner replenishing means 140 connected to No. 4 is accommodated.

The photoconductor drum 10, the charger 12 and the cleaning device 22 are integrated into a drum cartridge 30 while the developing devices 14 and the toner replenishing means 140 are integrated into a drum base 40. Has been done.

As shown in FIG. 7, the drum base 40 can be moved substantially horizontally from the mounting position (shown by the broken line) with respect to the apparatus main body and set to the pulling-out position. The drum cartridge 30 of
The conveyance surface of the recording paper P is widely opened by retreating from the position (shown by the broken line) where the image formation is possible following the movement of the drum base 40.

FIG. 8 shows the state in which the drum base 40 is placed in its mounting position and the drum cartridge 30 is fixed to the image forming apparatus, while FIG. 9 shows the state in which the drum base 40 is moved to the pull-out position and the drum cartridge 30 is in the image position. It shows a state in which the drum cartridge 30 is supported on the drum base 40 without being retracted and fixed from the formation position, and the drum cartridge 30 side is shown by a one-dot chain line and the drum base 40 side is shown by a two-dot chain line for convenience of illustration.

A first guide member 50 composed of an upper rail 51 and a lower rail 52 and a guide roller 53 are provided opposite to each other on the inner surfaces of the side panels 1 and 2 in the apparatus main body described above. .

On the other hand, the drum base 40 has
It has a plate-like member 41 provided with a rotating roller 42, and is supported by engaging the rotating roller 42 with the guide member 50 and the plate-like member 41 itself with the guide roller 53.

In the mounting position of the drum base 40, the rotating roller 42 is placed at a position where it has finished descending the inclined surface 52A at the tip of the lower rail 52 due to its own weight, and the plate-shaped member 41 and the rear end are arranged. The notch 41A is engaged with the guide roller 53 to determine the upper and lower positions and the front and rear positions, and the restriction pin 43 provided on the front surface of the pedestal and the restriction hole of the abutment plate 54 provided between the side panels. And is restricted in vertical movement.

Further, a guide plate 61 having an opening 61A and an elastic member (not shown) around a shaft 62A as a fulcrum are provided on the inner surfaces of the side panels 1 and 2 provided in the apparatus body counterclockwise within a predetermined angle. Locking lever 62 biased to
A second guide member 60 composed of and is provided opposite to each other.

On the other hand, in the drum cartridge 30, both ends of the drum shaft 10A for rotatably supporting the photosensitive drum 10 are projected to the left and right side surfaces thereof, and the drum shaft 10A is mounted at the mounting position of the drum mount 40. The guide plate 61
The position of the photosensitive drum 10 is set by further pressing the locking lever 62 in the state of being engaged with the opening 61A.

In the drum cartridge 30, in the state where the position of the photosensitive drum 10 is set, the pair of left and right compression springs 44 provided on the front surface of the drum base 40 press the rising portion 30A of the drum cartridge 30 main body, and the above-mentioned device is used. The abutment plate 54 of the main body is brought into pressure contact with the drum, so that the drum cartridge 30 is set at a position where an image can be formed.

The photosensitive drum 10 thus set in position
The abutting roller 141 of each developing device 14 is urged to the peripheral surface of
A is pressed to form a predetermined developing gap with the peripheral surface of the developing sleeve 141, and on the other hand, the gears and electrical contacts between the drum cartridge 30 side and the apparatus main body side are automatically connected. As a result, power and electric power required for image formation can be supplied and controlled.

In the drum mount 40, the plate-like member 41 rolls the rotating roller 42 on the one hand in the guide member 50, and on the other hand, the lower edge following the notch 41A is set on the guide roller 53. By sliding along it, it is moved to the front of the apparatus main body and pulled out as shown in FIG.

In the initial stage of the movement of pulling out the drum base 40, on the one hand, the rotating roller 42 ascends along the inclined surface 52A of the lower rail 52, and on the other hand, the inclined surface of the notch 41A rides on the guide roller 53. Of the plate-shaped member at the same time at a position where the restriction roller 43 is released from the engagement with the abutting plate 54 and is pulled out while the rotation roller 42 is locked to the end of the guide member 50. The locking portion 41B formed on the lower edge of 41 is engaged with the guide roller 53 and stopped.

When the movement of the pulling-out operation of the drum base 40 is started, each developing device 14 is retracted to the outside of the pressure contact operating range with respect to the photosensitive drum 10, while the drum cartridge 3
0 is released from the pressing force of the compression spring 44, and the receiving portion 30B formed at the upper portion is directly supported by the plate member 41 due to the rise of the drum base 40, and the protrusion 4 on the upper side thereof.
By the engagement of 1C, it is moved integrally with the drum base 40 and pulled out.

As a result, in the drum cartridge 30, the end portions of the drum shaft 10A protruding to the left and right side surfaces are forcibly rotated and retracted in the clockwise direction against the urging force of the locking lever 62 described above to guide the guide plate 61. The opening 61A of the recording sheet P, and while being supported without being fixed to the drum stand 40, the recording sheet P is moved to the drawing position to open the conveyance surface of the recording sheet P widely, and maintenance such as jam removal or replacement of equipment is performed. Make the work easier.

The drum mount 40 is raised to a predetermined height in the initial stage of movement as described above.
Also, since the amount of rise H2 of the drum cartridge 30 caused by the movement of the drum base 40 is restricted by the slope of the inclined surface 52A, the peripheral surface of the photosensitive drum 10 is retracted from the pressure contact operation range of the transfer roller 18. Is lacking in
Therefore, by releasing the pressure contact operation of the transfer roller 18 itself, a sufficient gap is formed between the photosensitive drum 10 and the transfer roller 18.

The drum base 40 in the pulled-out position is moved by sliding the plate-shaped member 41 in the horizontal direction by releasing the engagement with the guide roller 53 by pressing the drum base 40 from the state shown in FIG. The amount of increase H mentioned above at the end
The plate-like member 41 is lowered by one position and is again attached to the position shown in FIG. 8 with the plate-like member 41 engaged with the guide roller 53. By utilizing the gravity in this way, it is possible to stably shift to the mounted state.

On the other hand, the drum cartridge 30 slides horizontally following the movement of the drum base 40, and at the same timing as the lowering of the drum base 40, the drum shaft 10A is lowered by the guide of the guide plate 61 and the locking lever 62 is moved. 8 is forcibly rotated to be locked and fixed at the position shown in FIG. 8, and then the compression spring 44 of the drum base 40 is pressed to reset the drum cartridge 30 to the image forming position. The drum mount 40 has a descending amount corresponding to the above-described ascending amount H1 while the drum cartridge 30 has a descending amount corresponding to an ascending amount H2 slightly smaller than the above-described ascending amount H1 of the drum mount 40. Since there is a gap between the drum cartridge 40 and the drum base 40, the drum cartridge 30 is set at a predetermined image forming position without being constrained by the drum base 40.

In the above-described embodiments, the drum-shaped image forming body is described as the image forming body, but the present invention also includes a belt-shaped image forming body stretched between rollers.

[0053]

According to the present invention, when an abnormal situation such as a jam or a failure occurs at the time of transferring an image, it is possible to automatically cancel the pressing action of the transfer means with respect to the image forming body, and the cancellation can be performed. Since the operation is performed after a predetermined time has passed after the image forming body is stopped, an image forming apparatus is provided which can safely and easily perform jam processing and other maintenance without damaging the image forming body. became.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus.

FIG. 2 is a pressure contact mechanism diagram of a transfer unit (first).

FIG. 3 is a press contact mechanism diagram of a transfer unit (No. 2).

FIG. 4 is a time chart showing a pressure contact operation of a transfer unit.

FIG. 5 is a flowchart of an abnormal stop task.

FIG. 6 is a plan layout view of the color image forming apparatus.

FIG. 7 is a cross-sectional configuration diagram showing a drawing position of the image forming body.

FIG. 8 is a cross-sectional view of essential parts showing the configuration when the image forming body is attached.

FIG. 9 is a cross-sectional view of essential parts showing the configuration when the image forming body is pulled out.

[Explanation of Codes] 10 Photosensitive Drum 12 Charging Device 13 Image Exposure Means 14 Developing Device 15 Paper Feeding Cassette 17 Paper Feeding Roller 18 Transfer Roller 20 Fixing Device 22 Cleaning Device 70 Cam Plates 70A, 70B, 70C, 70D, 70E Notches 80 Pressing member 81, 91 Tension spring 82 Pressing pin 90 Pressing lever 92 Protrusion R, r Curvature radius S Photo sensor C Cam M Pulse motor

Claims (2)

[Claims] 1. An image forming body, a charging means for charging the image forming body, an image exposing means for exposing the image forming body to an image, and a latent image formed on the image forming body. An image forming apparatus comprising: a developing unit that develops a toner image, a transfer unit that transfers the toner image onto a transfer material, and a fixing unit that fixes the transferred toner image onto the transfer material, The apparatus is configured by a first main body including at least the transfer unit, and a second main body that is attachable to and detachable from the first main body in a substantially horizontal direction and includes at least the image forming body. An image forming apparatus comprising: a control unit that stops the operation of a main drive system including the unit and releases the pressure-bonding action of the transfer unit to the image forming body. 2. The control means controls so that the pressure-bonding action of the pressure-bonding means of the transfer means with respect to the image forming body is released after a lapse of a predetermined time after the operation of the main drive system is stopped. 1. The image forming apparatus according to 1.