JP3521533B2 - Paper transport control method for image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of sheet conveying units, and more particularly to an image forming apparatus constructed so that the jammed sheet can be easily removed when a jam occurs in the sheet conveying unit. The present invention relates to a paper transport control method.

[0002]

2. Description of the Related Art For example, as an output device of an electrophotographic copying machine, a laser beam printer, an LED printer, a facsimile, or a word processor, a belt-shaped or drum-shaped transfer material carrying member is electrostatically adsorbed on a sheet to remove the paper from the photoconductor. The image forming apparatus of the type that electrostatically transfers the image information of (3) is widely adopted.

In this type of image forming apparatus, if there is a gap between the transfer material carrying member and the sheet due to the state of the leading edge of the sheet, the sheet is transferred due to a peeling discharge phenomenon during transfer of the toner image formed on the photoconductor. A so-called pop jam (POP-JAM: P) that is peeled off from the material carrying member and electrostatically adsorbed on the photoconductor side.
Aper On Photoreceptor-Ja
m), or paper jam called wrapping jam may occur.

For this reason, in this type of image forming apparatus, it is necessary to provide a measure for preventing a jammed wrap or a measure for stopping the damage to the device to a minimum when a wrapping jam occurs, and a means for easily removing the jammed paper. There is.

[0005]

In the prior art, a gripper system in which the leading end of a sheet is mechanically held by a transfer material carrying member, and JP-A-63-257773 and JP-A-4 are disclosed.
As disclosed in Japanese Patent Application Laid-Open No. 278976 and Japanese Patent Application Laid-Open No. 5-94095, the winding jam is controlled by controlling the photoconductor-side or transfer-side factor corresponding to the leading edge of the paper to prevent the peeling discharge phenomenon from occurring. There are known methods to prevent the occurrence of (pop jam), but in either method, the effective image area of the leading edge of the paper has a large receding area, so that an image cannot be placed on the image. It has the drawback of being lost.

Further, among other prior arts, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 2947601, a device is provided to prevent the paper from peeling off from the transfer material carrying member by providing a guide upstream of the contact between the photosensitive member and the transfer material carrying member, and as described in Japanese Patent Application Laid-Open No. 5-281861. Japanese Patent Application Laid-Open No. 2004-242370 discloses a paper pressing member provided upstream of the transfer unit to prevent winding jam by taking measures to prevent the paper from bending toward the photoconductor.

However, in any of the above-mentioned conventional techniques, for example, when a sheet left under high humidity has its tip deformed due to moisture absorption, an image is formed on the first side after a fixing step. There is no ability to cope with the occurrence of a jam on the sheet after being folded, and this is not an effective method for suppressing the occurrence of a jam around the photoconductor while maintaining the effective image area at the leading end.

Therefore, as a measure to minimize the damage to the device when a winding jam occurs, the purpose is to detect the occurrence of the winding jam promptly and stop the device.
For example, regarding the arrangement of the sensors and the detection sequence, as shown in JP-A-1-109383, after detecting a jam, a part of the inside of the apparatus is reversed so that the wound jammed paper can be easily taken out.

Further, the present applicant previously made a transfer material such as a paper electrostatically adsorbed and held on a belt-shaped transfer material carrying member,
In an image forming apparatus of a system that obtains a multicolor image by transferring a toner image, which is image information, while transferring a transfer material along a plurality of image transfer portions that transfer image information from a photoconductor, If a peeling defect occurs when peeling a transfer material such as a sheet from the transfer material supporting member after the image transfer is completed, the transfer material supporting member is reversed so that the jammed paper can be easily taken out. .

In the case of an image forming apparatus having a plurality of image transfer portions, a plurality of sheets may exist in the apparatus when a winding jam occurs. Further, those sheets may be spread over a plurality of units (a sheet transport unit that constitutes a transfer unit including a photoconductor, a sheet transport unit that constitutes a fixing device, a sheet feeding or sheet circulating unit, etc.). .

An object of the present invention is to make it possible to easily take out a wrapping jammed paper that has occurred in a paper conveyance path extending between units having a plurality of image transfer sections and the papers before and after the wrapping jammed paper without causing damage to the apparatus. Another object of the present invention is to provide a paper transport control method for the image forming apparatus.

[0012]

In order to achieve the above object, the present invention provides a paper transport unit having a unique transport drive system for transporting a plurality of papers, and a unit within or between the units. The sheet detecting means is disposed at the position for detecting the sheet conveying state, and the control means for controlling the operation of each unit based on the information from the sheet detecting means.

That is, the first invention according to claim 1 is the first paper transport unit for transporting a paper, and the first paper transport unit.
It is located downstream of the paper transport unit in the paper transport direction and
Transports the paper transported by the first paper transport unit
A plurality of paper transport units including at least a second paper transport unit, an in-unit paper detection unit installed in the first paper transport unit, and a space between the first paper transport unit and the second paper transport unit. The inter-unit sheet detection means and the drive control means for controlling the operation of the plurality of sheet transport units, wherein the drive control means is configured such that the in-unit sheet detection means installed in the first sheet transport unit detects the sheet. When a conveyance error is detected,
The sheet transport operation of the second sheet transport unit is stopped based on the sheet presence detection signal of the inter-unit sheet sensor, and the sheet transport operation of the second sheet transport unit is stopped . Accordingly, the paper transport operation of the first paper transport unit is stopped, and the transport operation is performed by a predetermined distance in the direction opposite to the regular transport direction, so that the paper can be easily removed from the first paper transport unit. It is characterized by According to a second aspect of the present invention, in the first aspect of the invention, the first sheet conveying unit comprises an image transfer device including one or a plurality of photosensitive drums and a transfer belt, and the second sheet conveying unit. Is a fixing device for fixing the transferred sheet discharged from the first sheet conveying unit 30.

The third invention according to claim 3 is
In order to clarify the correspondence with the embodiment, the description will be given with reference numerals, and the first paper transport unit 3 that constitutes the image transfer device will be described.
0, a second paper transport unit 31 which constitutes a fixing device for fixing the transferred paper discharged from the first paper transport unit 30, and a paper delivery device which feeds the paper to the first paper transport unit 30. A plurality of sheet conveying units including at least a third sheet conveying device 32; in-unit sheet detecting means 64, 65, 66, 67 installed in the first sheet conveying unit 30;
An inter-unit sheet detection unit 68 installed between the sheet transport unit 30 and the second sheet transport unit 31 and a drive controller 84 for controlling the operation of the plurality of sheet transport units are provided, and the drive controller 84 includes: In-unit sheet detection means 64 installed in the first sheet transport unit 30,
When 65, 66, and 67 detect a paper conveyance abnormality, based on the detection signal of the presence of paper by the inter-unit paper detection means 68 installed between the first paper conveyance unit 30 and the second paper conveyance unit 31. The second paper transport unit 3
No. 1 paper transport operation is stopped , and the paper transport operation of the first paper transport unit 30 is stopped in response to the stop of the paper transport operation of the second paper transport unit 31 and the first paper transport unit 30 is properly operated. The sheet conveying operation is performed for a predetermined distance in the opposite direction to the sheet conveying direction, and the first sheet conveying unit 30 and the third sheet conveying device 32 are provided.
When the inter-unit sheet detection means 63 installed between the sheets detects the presence of the sheet, the sheet is conveyed to the first sheet conveyance unit 3
It is characterized by facilitating the removal of the sheet from the image transfer device by executing the conveying operation of pushing the sheet into the 0.

Further, a fourth invention according to claim 4 is
The sheet detecting means in the first sheet conveying unit is arranged on the sheet conveying path downstream of the transfer device. Further, a fifth aspect of the present invention is characterized in that the sheet detecting means in the first sheet conveying unit is arranged upstream of a cleaning member provided around the photosensitive drum.

In the first, second, third, fourth, or fifth invention of the present invention, the following configuration can be adopted. (1) The conveyance operation of the second sheet conveyance unit is stopped by releasing the pressure between the fixing rolls constituting the fixing device.
Stop . (2) From the time when the paper detecting means of the first paper carrying unit detects a paper carrying abnormality, it is detected whether or not there is a paper between the first paper carrying unit and the second paper carrying unit. Delay the time required for.

(3) When the paper detecting means of the first paper carrying unit detects a paper carrying abnormality, it is detected whether or not there is a paper between the first paper carrying unit and the second paper carrying unit. When the presence of paper is detected by the information from the paper detecting means,
Delay the time to stop . (4) The time from when the stop of the sheet conveyance of the second sheet conveyance unit is detected until the conveyance of the first sheet conveyance unit is stopped is delayed.

(5) After stopping the sheet conveyance of the first sheet conveyance unit, a control device provided in advance in the apparatus has a time for operating the first sheet conveyance unit in the direction opposite to the regular sheet conveyance direction. It is determined by the count value of the timer set in the CPU in the logical operation circuit that constitutes it. (6) The time for operating the first paper transport unit in the direction opposite to the regular paper transport direction after stopping the paper transport of the first paper transport unit is determined by the information of the paper detection means for detecting the paper transport state. decide.

(7) After stopping the sheet conveyance of the first sheet conveying unit, the time for operating the first sheet conveying unit in the direction opposite to the regular sheet conveying direction is set to the transfer device immediately before the sheet front end portion. The paper transport direction of the first paper transport unit is operated in the reverse direction until it returns to the position. (8) A means for judging the size of the sheet for which the conveyance abnormality is detected, and a storage means for storing the position where the conveyance abnormality has occurred are provided on the sheet conveyance path from the first sheet conveyance unit based on these information. The operation of the third sheet transport unit located upstream is controlled.

(9) A judgment means for judging the presence or absence of the succeeding paper after the paper for which the conveyance abnormality is detected is provided, and the third paper conveyance which is upstream of the first paper conveyance unit on the paper conveyance path based on the information. Control the operation of the unit. (10) A determination unit that determines whether the sheet for which the conveyance abnormality is detected is the sheet that is being transferred on the first side or the sheet that is being transferred on the second side. The operation of the third unit located upstream in the sheet conveyance path is controlled.

(11) The first paper transport unit can be attached to and detached from the apparatus main body. (12) The plurality of transfer devices forming the first paper transport unit can be attached to and detached from the plurality of photoconductors. (13) The first paper transport unit and the second paper transport unit can be attached to and detached from the apparatus main body at the same time.

[0022]

When a jam occurs in the image forming apparatus as well as the winding jam, some units are arranged to be detachable from the apparatus main body so that the user can easily take out the jammed paper. For example, a unit such as a photoconductor unit that is likely to be damaged when being attached or detached is often arranged so that the user cannot attach or detach it.

When a plurality of units cannot be attached / detached at the same time, when only one unit is attached / detached, a part of the paper is broken and remains in the device or the device is damaged when only one unit is attached / detached. May be given. According to the present invention, in such a case as well, by determining the operation of each unit from the paper position information between units or within the unit, the paper conveyed before and after the wrapped jam paper can be prevented from causing damage to the apparatus. It can be taken out.

That is, in the structure of the first aspect of the invention, the first paper transport unit is provided with in-unit paper detection means for detecting the presence or absence of the transported paper inside the first paper transport unit. In addition, the first paper transport unit and the second paper transport unit
Between the paper transport units, inter-unit paper detection means for detecting the presence / absence of paper existing across both units is installed.

Then, the drive control means controls the operation of the plurality of paper transport units to control the paper transport so that the paper is positioned at a position where the jammed paper can be easily taken out. That is, the drive control means, when the in-unit sheet detection means installed in the first sheet conveyance unit detects an abnormality in sheet conveyance, the drive control means is configured to detect the presence of the sheet by the inter-unit sheet detection means. 2 The paper transporting operation of the paper transporting unit is stopped , and the paper transporting operation of the first paper transporting unit is stopped in accordance with the stop of the paper transporting operation of the second paper transporting unit, and the normal transport direction is reversed. By carrying out the carrying operation for a predetermined distance, it becomes easy to remove the paper from the first paper carrying unit.

According to a second aspect of the present invention, the first sheet conveying unit in the first aspect of the invention is an image transfer device including one or a plurality of photosensitive drums and a transfer belt. The second paper transport unit is the first
As a fixing device for fixing the transferred paper discharged from the paper carrying unit 30, the jammed paper being transferred and the paper conveyed to the fixing device after the transfer are jammed, the jammed paper can be easily taken out. To do.

In the structure of the third aspect of the present invention, the first sheet conveying unit is provided with in-unit sheet detecting means for detecting the presence / absence of conveyed sheets in the first sheet conveying unit. In addition, an inter-unit sheet detection unit for detecting the presence or absence of sheets existing between the first sheet conveyance unit and the second sheet conveyance unit and existing between the units, and the third sheet conveyance unit and the first sheet conveyance unit. An inter-unit sheet detection unit for detecting the presence / absence of sheets existing across the sheet conveyance units is installed.

Further, the drive control device controls the operation of the plurality of paper transport units to control the paper transport so as to position the paper at the position where the jammed paper can be easily taken out. That is, the drive control device is based on the detection signal of the presence of the paper of the inter-unit paper detection means when any of the intra-unit paper detection means installed in the first paper conveyance unit detects the paper conveyance abnormality. Stop the sheet conveying operation of the second sheet conveying unit, stop the sheet conveying operation of the first sheet conveying unit in response to the stop of the sheet conveying operation of the second sheet conveying unit, and determine the normal conveying direction. The conveyance operation is performed in the reverse direction by a predetermined distance, and the first sheet conveyance unit 30
When the inter-unit sheet detecting means 63 installed between the third sheet conveying device 32 and the third sheet conveying device 32 detects the presence of the sheet, the sheet is pushed into the first sheet conveying unit 30 and the conveying operation is performed, whereby the first sheet is conveyed. Makes it easy to remove paper from the paper transport unit.

Further, in the structure of the fourth aspect of the present invention, the sheet detecting means in the first sheet conveying unit is arranged on the sheet conveying path downstream of the transfer device so that the sheet is exposed to light. Detects the occurrence of so-called pop jam around the body drum. Further, according to the fifth aspect of the present invention, the sheet detecting means in the first sheet conveying unit is arranged upstream of the cleaning member provided around the photosensitive drum, so that the jammed sheet can be prevented. The rotation of the transfer drum is stopped before entering the cleaning member.

The above-mentioned first, second, third, fourth, or fifth
The configurations (1) to (13) adopted in the configuration of the invention of (1) operate as follows. (1) By stopping the conveyance of the second sheet conveyance unit by releasing the pressure between the fixing rolls constituting the fixing device, it is possible to avoid jamming of the fixing roll.

(2) Whether or not there is a sheet between the first sheet conveying unit and the second sheet conveying unit after the sheet detecting means of the first sheet conveying unit detects the sheet conveying abnormality. By delaying the time required for detection, the conveyance time difference between the transfer belt and the fixing roll is adjusted. (3) Paper detection for detecting whether or not there is a paper between the first paper carrying unit and the second paper carrying unit when the paper detecting means of the first paper carrying unit detects a paper carrying abnormality The time from the detection of the presence of paper to the stop of the transportation of the second paper transportation unit is delayed by the information from the means to adjust the transportation time difference between the transfer belt and the fixing roll.

(4) A paper jam occurs on the fixing roll by delaying the time from when the stop of the sheet conveyance of the second sheet conveyance unit is detected until the conveyance of the first sheet conveyance unit is stopped. Prevent. (5) After stopping the sheet conveyance of the first sheet conveyance unit by the timer set in the CPU in the logical operation circuit that constitutes the control device provided in the apparatus in advance, the first
The time for operating the paper transport unit in the direction opposite to the regular paper transport direction is determined.

(6) Based on the information of the paper detecting means for detecting the paper carrying state, after the paper carrying of the first paper carrying unit is stopped, the first paper carrying unit is moved in the direction opposite to the normal paper carrying direction. The time to operate is decided. (7) After the sheet conveyance of the first sheet conveyance unit is stopped, the time for operating the first sheet conveyance unit in the direction opposite to the regular sheet conveyance direction is returned to the position of the immediately preceding transfer device with the leading end of the sheet. Until then, the paper transport direction of the first paper transport unit is operated in the reverse direction.

(8) Based on information from the means for judging the size of the paper for which the conveyance abnormality has been detected and the storage means for storing the position where the conveyance abnormality has occurred, on the paper conveyance path more than the first paper conveyance unit, The operation of the third sheet transport unit located upstream is controlled. (9) The operation of the third sheet transport unit upstream of the first sheet transport unit on the sheet transport path is controlled by the information of the determination unit that determines the presence or absence of the sheet following the sheet for which the transport abnormality is detected. .

(10) Based on the information of the judging means for judging whether the paper for which the conveyance abnormality is detected is the paper which is being transferred on the first surface or the paper which is being transferred on the second surface, it is more than the first paper carrying unit. The operation of the third unit located upstream on the paper transport path is controlled. (11) Since the first paper transport unit can be attached to and detached from the apparatus body, the jammed paper can be easily removed.

(12) The plurality of transfer devices forming the first paper transport unit can be attached to and detached from the plurality of photoconductors, so that the jammed paper can be easily removed. (13) Since the first sheet transport unit and the second sheet transport unit can be attached to and detached from the apparatus main body at the same time, the jammed sheet can be easily removed.

[0037]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of an embodiment of an image forming apparatus according to the present invention, which is 2Y, 2M, 2C, 2
K is yellow (Y), magenta (M), cyan (C),
Black: Photoconductor drum corresponding to each color of black (K), 3
Y, 3M, 3C and 3K are primary chargers, 4Y, 4M and 4
C and 4K are exposure beams, 5Y, 5M, 5C and 5K are developing devices, 6 is a transfer device, 7 is a transfer belt, and 8Y, 8M and 8
C and 8K are transfer chargers, 9 is a drive roll, and 10 and 1
1, 12 are driven rolls, 13 are counter electrodes, 14 are adsorption chargers, 15 are guide members, 15Y, 15M, 15C, 1
5K is a cleaning member for the photosensitive drum, 20 is a stripping static eliminator, 21 is a stripping nail, 23 is an internal static erasing charger, 24 is an external static erasing charger, and 25-1 and 25-2 are transfer belt cleaning means ( Cleaning member).

Further, 100 is a fixing device (fixing device including a fixing roll), 112-1, 112-2 and 112-3 are paper supply trays, 113 is a paper conveying path for double-sided printing,
114-1, 114-2, 114-3, 120-122
Is a transport roll, 116, 117, 118, and 119 are discharge transport rolls, 124 is a paper delivery roll (registry roll), 125 is a sheet transport path confluence point, 127 is a reversal point, 128 to 134 are transport rolls, and 129 is movable. It is a paper guide.

In the figure, this image forming apparatus has four photosensitive drums 2Y, 2 corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K).
M, 2C, and 2K are arranged in this order from the right side of the drawing, that is, at a predetermined distance from the registration roll 124 side. The primary chargers 3Y, 3M, 3C, 3 are provided near the outer circumferences of these photosensitive drums 2Y, 2M, 2C, 2K, respectively.
K is provided. These primary chargers 3Y, 3M,
3C and 3K are corresponding photoconductor drums 2Y and 2Y, respectively.
The surfaces of M, 2C and 2K are uniformly charged to a specific level between -800 and 800V, for example.

Further, the photosensitive drums 2Y, 2M, 2C,
Exposure devices, such as a laser beam exposure device, are provided downstream of the primary chargers 3Y, 3M, 3C, 3K near the outer periphery of 2K in the rotational direction.
C and 4K scan the surfaces of the photoconductor drums 2Y, 2M, 2C and 2K. Further, the exposure beam 4Y near the outer periphery of each photoconductor drum 2Y, 2M, 2C, 2K,
Developing devices 5Y, 5M, 5C, and 5K are provided on the downstream side in the rotational direction of the scanning regions of 4M, 4C, and 4K, respectively.

Exposure beams 4Y, 4M, 4 from the exposure device
C and 4K are modulated with the light image obtained by each color separation or the light image corresponding thereto to form an electrostatic latent image on the photoconductor drums 2Y, 2M, 2C and 2K. Developing devices 5Y, 5M, 5C, 5
K develops this electrostatic latent image with toner to visualize it as a toner image. Each photoconductor drum 2Y, 2M, 2C, 2
Below K, a transfer device 6 is arranged. The transfer device 6 includes an endless transfer belt 7 of a predetermined length arranged in contact with each of the photoconductor drums 2Y, 2M, 2C and 2K, and the lowermost part of the photoconductor drums 2Y, 2M, 2C and 2K. Transfer chargers 8Y, 8M, 8 arranged to face the transfer positions, respectively.
It consists of C and 8K.

The transfer belt 7 is composed of a conveying sheet made of a dielectric material using a resin film such as polyethylene terephthalate (PET), polycarbonate (PC), or polyvinylidene fluoride (PVDF). The transfer belt 7 includes a drive roll 9 connected to a dedicated transfer belt drive source (not shown) having excellent constant speed and one or more driven rolls (9 to 1 in FIG. 1).
2) It is stretched with a certain tension applied between it and
Further, it is rotated by the drive roll 9 in the direction of arrow A, that is, in the counterclockwise direction.

The transfer chargers 8Y, 8M, 8C and 8K are corona chargers, for example, +4.2 kV to +12.0 kV.
Different voltages are applied in the respective ranges and the total discharge current is +50 μA to +2000 μA. Part of this transfer current flows into the photoconductor drums 2Y, 2M, 2C, 2K, and the toner images on the photoconductor drums 2Y, 2M, 2C, 2K are transferred onto the transfer material (paper) adsorbed on the transfer belt 7. Transfer.

Between the drive roll 9 of the transfer belt 7 and the first transfer charger 8Y, an attraction charger 14 for attracting a sheet to the transfer belt 7 and a transfer material are transferred in opposition to the attraction charger 14. A guide member 15 for guiding the belt 7,
Opposite electrodes 13 of the adsorption charger 14 are provided respectively. FIG. 2 is a schematic view of a main part for explaining the configuration around the sheet peeling means and the transfer device. 68 and 69 are sheet detection sensors,
The same reference numerals as those in FIG. 1 correspond to the same parts.

That is, a peeling means for peeling the sheet from the transfer belt 7 is arranged downstream of the final transfer charger 8K on the transfer belt 7. This peeling means uses the driven roll 10 as a peeling roll for peeling by utilizing the “strain” of the paper by bending the transfer belt 7, and at the same time, the transfer roll 7 is transferred to the outside of the transfer belt 7 near the driven roll 10. The peeling static eliminator 20 is arranged toward the belt 7, and the peeling claw 21 is arranged outside the transfer belt 7 near the peeling position.

Further, on the outside of the transfer belt 7, an inner charge-eliminating charger 23 and an outer charge-eliminating charger 24, which constitute a charge-eliminating means for eliminating charge of the transfer belt 7, are provided at a position downstream of the final transfer charger 8K. They are arranged so as to face each other with the belt interposed therebetween. Further, transfer belt cleaning means 25-1 and 25-2 for cleaning the transfer belt 7 are arranged between the charge removing means for removing the charge on the transfer belt 7 and the attraction charger 14.

FIG. 3 is a schematic view of a main part for explaining the structure of the sheet feeding section for the transfer belt, and 63 is a sheet detection sensor.
The same reference numerals as those in FIG. 1 correspond to the same parts. That is, the sheets accommodated in the sheet supply tray 112 pass through the respective sheet supply paths from the respective sheet supply trays 112-1, 112-2, 112-3, and then the transfer belt 7 described above.
Is guided to the guide member 15 and is electrostatically attracted to the transfer belt 7 by the attraction charger 14 described above. Rolls (114, 116, 117, 124) having drive sources arranged at regular intervals are arranged in the paper feeding path, and the timing for reaching the transfer belt 7 at a desired speed and timing can be adjusted. it can.

The sheet electrostatically attracted to the transfer belt 7 is conveyed on the transfer belt 7 and reaches the transfer position of the yellow (Y) photoconductor drum 2Y. Transferred from the drum 2Y to a sheet. Next, the sheet is conveyed by the transfer belt 7, and the magenta (M) toner image is transferred from the photosensitive drum 2M to the sheet. Thereafter, in the same manner, the cyan (C) toner image and the black (K) toner image are sequentially transferred so as to be superposed on the transfer toner image on the paper. In this way, four-color full-color multiple transfer is performed.

When the full-color multi-transfer of four colors is completed, the paper is electrostatically or mechanically transferred from the transfer belt 7 by the action of the peeling roll (following roll) 10, the peeling static eliminator 20, the peeling claw 21, and the like. Fixing device 1 for peeling off and fixing the toner image to the paper thermally or pressureally
Sent to 00. In the single-sided print mode in which only the one side of the paper that has undergone the fixing process is printed, the discharge transport roll 1
It is discharged to the outside of the machine (outside of the device) by 18, 19. Also,
In the double-sided print mode, the discharge transport roll 118
After passing through the sheet, the movable sheet guide 129 does not discharge the sheet to the outside of the machine but sends it to the sheet conveying path for double-sided printing.

After the trailing edge of the sheet fed downward in the drawing by the conveying rolls 120, 121, 122 in the sheet conveying path for double-sided printing passes through the reversal point 127,
The paper is temporarily stopped, then is fed in the reverse direction of the front and rear ends in the direction of the paper transport path 113 for double-sided printing, and returns to the normal paper transport path. In this way, full-color double-sided printing is automatically performed.

However, when the sheet is conveyed through such a complicated route, a sheet conveyance abnormality caused by the state of the sheet or the state of the image forming apparatus is detected, and damage such as damage to the apparatus or breakage of the sheet is detected. It is common practice to provide a minimum of stopping means. FIG. 4 is a schematic view for explaining the arrangement of the paper detection sensor arranged in the image forming apparatus shown in FIG. 1, and 30 is a first portion including an image transfer device.
Paper transport unit, 31 is a second paper transport unit including a fixing device, 32 is a third paper transport unit including a paper feeding device, 33 is a fourth paper transport unit including a paper reversing device, and 34 is a double-sided print paper transport path. And a fifth paper transport unit including a paper feed tray, a sixth paper transport unit including a paper transport path from the paper supply tray, and reference numerals 36, 37 and 38 including seventh, eighth and ninth paper transport units including a paper feed tray.
Numerals 75 to 75 are paper detection sensors, 84 is a drive control means (paper conveyance control device), and the same reference numerals as those in FIG. 1 correspond to the same parts.

As shown in the figure, the paper detection sensor 51
Paper information from ~ 75 to the central controller (machine C
(PU) is compared with the information of the determination means incorporated in the PU to determine a paper conveyance abnormality, and the entire apparatus (all units) or a part of the apparatus (one or more units) is emergency stopped to damage the apparatus or to remove the paper. Control to minimize damage such as breakage.

The information from the sheet detection sensors 51 to 75 arranged in the image forming apparatus has various detection specifications depending on the arranged positions. For example, if the detection means is an optical sensor and outputs a high level (H) when there is paper and a low level (L) when there is no paper, the detection specification 1 is that the output changes from L to H by the reference time. If it is not switched, it may be determined that the paper conveyance is abnormal. That is, this is a case where it is determined that the leading edge of the sheet has not reached the reference position by the reference time. It is determined that the sheet has a conveyance abnormality upstream of the detection position.

As the detection specification No. 2, there is a case where it is determined that the paper conveyance is abnormal unless H → L is switched by the reference time. In this case, when it is determined that the trailing edge of the sheet cannot be completely removed from the sensor by the reference time, the sheet has a conveyance abnormality downstream of the detection position and at a position closer than the length of the sheet. Is judged. Furthermore, as the detection specification No. 3, the output is L regardless of the time.
If it is switched to → H, it may be determined that the paper conveyance is abnormal. In this case, it is a case where the portion where the paper is not originally traveled is detected, and it is judged that the conveyance abnormality has just occurred in the detected portion.

In FIG. 4, transfer chargers 8Y, 8M, 8C, 8
The paper sensor 64 is provided inside the transfer belt 7 just downstream of K.
65, 66 and 67 are installed as paper sensors inside the unit. The paper sensors 64, 65, 66, 67 are provided when the paper is electrostatically attracted to the transfer belt 7 and when the paper passes through a transfer electric field formed by the transfer chargers 8Y, 8M, 8C, 8K. The sheet sensor is provided to detect a phenomenon (pop jam) in which a sheet is wound around the photoconductor drums 2Y, 2M, 2C, and 2K due to a peeling discharge phenomenon that occurs.

In this case, in terms of the above-mentioned detection specifications, it is sufficient to judge the sheet conveyance abnormality as the detection specification No. 1. However, the paper photosensitive drums 2Y, 2M, 2
In order to detect the phenomenon of wrapping around C and 2K, it is possible to detect the paper sensor even if it is arranged on the photosensitive drums 2Y, 2M, 2C and 2K. In this case, in terms of the above-mentioned detection specifications, it is sufficient to determine a paper conveyance abnormality as detection specification No. 3.

Next, each paper transport unit in the image forming apparatus according to this embodiment will be described. FIG. 5 is an explanatory diagram of a unit configuration in the case where the above-described image forming apparatus is considered as a composite body of a plurality of sheet conveying units.
The same reference numerals as those in FIG. 4 correspond to the same portions.

In the figure, the first paper transport unit 30
Is a part including the transfer device 6, and is a unit downstream of the first paper transport unit 30 on the paper traveling path.
The unit of the portion including 0 is referred to as the second paper transport unit 31. Then, on the paper traveling path, the first paper transport unit 3
A unit including a transfer material feeding unit (paper feeding device) that is an upstream unit of 0 is referred to as a third paper feeding unit 32.

Further, in the above-mentioned sheet conveying path for double-sided printing, the portion where the transfer material can be removed from the left side when viewed from the front of the apparatus is unitized, and the portion is unitized as the fourth sheet conveying unit 3.
3, a part for removing paper from the front side of the apparatus is a fifth paper carrying unit 34, a part including three paper feeding units is a seventh paper carrying unit 36, and an eighth easy carrying unit 3, respectively.
The seventh and ninth paper transporting units 38 are defined as the sixth paper transporting unit 35, which is a part of the paper transporting path for double-sided printing that joins the paper transporting path from the paper feeding unit (seventh paper transporting unit 36). To do.

When a paper conveyance abnormality occurs, and the operation of stopping the entire device or a part of the device by the information from the above-described paper sensor to stop the damage of the device, the breakage of the transfer material 17, etc. is minimized. In the middle of the multiple-sheet double-sided print mode, paper is present in most units. As a method of removing such a plurality of sheets, a third sheet conveying unit 32 capable of removing the transfer material from the right side as viewed from the front of the apparatus and a range capable of removing the sheet from the left as viewed from the front of the apparatus. Seven sheet transport units 3 other than the unitized fourth sheet transport unit 33
0, 31, 34, 35, 36, 37, 39 are arranged so that they can be pulled out from the front of the apparatus body.

Further, the transfer device 6 which is the first paper transporting unit and the fixing unit which is the second paper transporting unit both require a highly accurate relative positional relationship for full-color image formation. It is necessary to attach / detach the paper transport unit at the same time, but if each unit is positioned in the device with high accuracy with respect to the main body of the device, it is possible to adopt a configuration in which each unit can be independently attached / detached. .

Therefore, only the photosensitive drums 2Y, 2M, 2C, 2K and the units of the image forming members around the photosensitive drums 2Y, 2M, 2C and 2K, to which the paper should not be originally conveyed, cannot be attached to and detached from the apparatus main body. Is the photoconductor drums 2Y, 2M,
2C, 2K replacement, developer replacement, and photoconductor drum 2
In order to replace the peripheral image forming members of Y, 2M, 2C, and 2K, it is required to be attachable to and detachable from the apparatus main body.

However, the photosensitive drums 2Y, 2M, 2C,
2K is a characteristic that is required to retain an electrostatic latent image and to be visualized by a developer, so that it can be attached and detached only by a specific user who performs maintenance of the apparatus, and for a user who normally removes abnormally conveyed paper. The current situation is that it is not removable. On the other hand, in this embodiment, all the units are detachable independently of the device.

Next, the arrangement of the paper transport unit and the paper sensor will be described. As described above, for example, when a paper conveyance error occurs in the middle of double-sided printing of a plurality of sheets, the entire apparatus or a part of the apparatus is emergency stopped to damage the apparatus,
Although the damage such as the breakage of the paper is minimized, the stop position is limited to not only the paper in which the conveyance error has occurred but also all the paper existing in the device running before and after it. There is a need.

Therefore, as shown in FIG. 5, the paper sensor is always arranged near the entrance and exit of each paper transport unit. When the paper is stopped across a plurality of paper transport units, when only one unit is attached to or detached from the apparatus main body, the paper may not be completely removed. In order to prevent this, it is necessary to change the stop timing of a part of the apparatus so that the sheet does not stop across a plurality of units, based on information from the sheet sensor arranged in the vicinity of the sheet conveying units. .

When the jam of the photosensitive member according to the present embodiment occurs, the image forming apparatus operates as follows. In the unit configuration of the image forming apparatus as described above, the sheet sensor, and the control method for the sheet in the apparatus when the sheet conveyance abnormality occurs, for example, the sheet sensor 65 shown in FIG. It is assumed that a conveyance abnormality is detected.

As shown in FIG. 4, the fact that the paper conveyance abnormality is detected inside the transfer belt 7 means that the leading edge of the paper is detected by the paper sensor within the reference time due to the occurrence of the jam around the photosensitive drum 2M as described above. It means that we could not reach 65. During continuous printing, the intervals between the sheets are set to a certain interval, and there are a plurality of sheets in the image forming apparatus.

FIG. 6 is an explanatory diagram of a specific example of the space between the sheets according to the difference in the sheet size in the carrying direction in the image forming apparatus of this embodiment. In this embodiment, the distance between the sheets during continuous copying is determined by the following requirements. When a dielectric film made of the above materials is used as the transfer belt, an endless so-called seamless belt, which originally has no seams (seams), can be manufactured, but considering the cost, etc., it is flat. It is general to use a belt having a seam by using a method such as ultrasonic welding of the dielectric film of (1).

In this case, the seam portion is different from the other portions in surface property and thickness, and effective and proper transfer is not performed, so it is excluded from the image forming area. In order to prevent an image from being formed at the joint portion in any case, it is possible to provide it by, for example, providing detection means for detecting the joint portion and always making the same position on the transfer belt the image forming area, that is, the transfer material adsorbing area. .

Further, when the length of the transfer belt is sufficiently longer than the maximum paper length, it is possible to secure an image forming area for several sheets in one round of the transfer belt. When the paper length is recognizable and shorter than the maximum paper length, it is possible to increase the number of image forming areas secured in one round of the transfer belt. It is possible to increase the number of prints per hour without changing.

In FIG. 10A, assuming that the length of the transfer belt 7 is 2100 mm and the maximum paper length is 432 mm, when the number of image forming areas secured for one round of the transfer belt is 4, (2100-432). × 4) ÷ 4 = 93 mm is the space between the sheets. In addition, in FIG.
When the number of image forming areas is 3, the distance between the sheets is (2100-432 × 3) / 3 = 268 mm.

Further, in FIG. 7C, when the paper length is 216 mm, and the number of image forming areas secured in one round of the transfer belt is 8, the space between the paper sheets is (21).
00-216 × 8) /8=46.5 mm. When the number of image forming areas secured for one round of the transfer belt is 6 when the paper length is 216 mm, (2100
−216 × 6) ÷ 6 = 134 mm.

The transfer belt shown in FIG. 6 is shown by being cut and developed at the seam portion. In this embodiment, the length of the transfer belt 7 is 2100 mm, the number of image forming areas secured in one round of the transfer belt is 8, the length of the paper is 210 mm, and the distance between the paper is 52.5 mm. .
Further, the photosensitive drums 2Y, 2M, 2C shown in FIG.
The interval of each 2K is 196 mm, and each transfer charger 8
The paper sensors 64, 65, 66 and 67 are arranged 49 mm downstream of the Y, 8M, 8C and 8K paper paths.

FIG. 7 is an explanatory diagram of each sheet position when a jam occurs when the sheet is wound around the photosensitive drum in the present embodiment, and 17 is a jam sheet wound around the photosensitive body 2M, and 17
a is the preceding paper (a), 17b is the preceding paper (b), 17c
Indicates preceding paper (c), 17d indicates preceding paper (d), 17e indicates succeeding paper (e), and 17f indicates succeeding paper (f). Although four sheets of preceding papers 17a to 17d and two sheets of succeeding papers 17e and 17f are shown in the figure, the preceding papers that may exist in the apparatus and the following papers 17e and 17f are shown. Subsequent sheets may be different.

In the figure, when a winding jam occurs on the photoconductor 2M, it is necessary to stop the photoconductor drum 2M at a timing at which the jammed jammed paper 17 does not enter the cleaning member 15M of the photoconductor drum 2M. . Further, when only the photoconductor drum 2M is stopped, the jammed paper 17 has the rear end thereof adsorbed to the transfer belt 7, so that the jammed paper 17 causes the transfer belt 7 and the cleaning member 15M of the photoconductor drum 2M to be separated. It is not preferable because it will exist in an uncontrollable posture in the meantime.

Therefore, when a winding jam occurs,
At least the photoconductor 2M and the transfer belt 7 where the winding jam has occurred need to be stopped immediately. In this case, the preceding sheet 17d in FIG. 7, that is, the jam sheet 1
Although the paper existing immediately downstream of 7 is detected by the paper sensor 66, there is no problem in taking it out of the paper transport unit 30.

However, the leading edge of the preceding two sheets of paper 17c located further downstream is restricted by the nip of the fixing device 100. Generally, when a transfer material such as a sheet is transported from a sheet transport unit to the next sheet transport unit as in the configuration of the image forming apparatus of this embodiment, the transport speed of each unit is not constant. This is because there is a fluctuation in the transport speed, and if the downstream unit is faster than the upstream unit, the transport materials such as transfer material will be pulled together, which may damage the paper or damage the unit. This is because it may lead to damage of the constituent transport members.

Therefore, the transport speed of the downstream paper transport unit, that is, the paper transport unit including the fixing device 100 in this case is set lower than the transport speed of the transfer belt 7. Therefore, the sheet is peeled from the transfer belt 7 and is gradually bent while being conveyed by the fixing device 100. However, when the transfer belt 7 is stopped, the fixing device 100 is stopped.
However, if it is not stopped before the above-described bending of the sheet is absorbed, the sheet may be broken or the transport member of the unit may be damaged.

For this reason, the fixing device 100 also needs to be stopped as soon as the photosensitive drum and the transfer belt, but the fixing device 100 cannot be stopped immediately in order to achieve the following characteristics. It is said that. That is, the fixing device 100 has a function of giving a thermal and pressure physical quantity to the toner on the paper and carrying the paper to the downstream side.
At the same time, a release agent is supplied to achieve a stable color image fixing process.

This release agent is often applied to a fixing roll constituting the fixing device 100 and transferred onto a transfer material, but is supplied to the fixing roll by a web or a donor roll. When stabilized, reversing the fuser roll leads to a reduction in the performance of the stable release agent supply member. Further, in order to stably fix the full-color image, a large amount of toner is required, and thus a large pressure is required as compared with the conventional monochrome image. In order to release this large pressure, it is most advantageous to gradually release the pressure as the fixing roll rotates. Therefore, due to the structure of the fixing device, when releasing the pressure, it is necessary to rotate the fixing roll in the forward direction.

In the fixing device having such a structure, when the preceding paper exists between the transfer belt and the fixing roll forming the fixing device, that is, the paper sensor 6 between the paper conveying units in FIG.
Only when the presence of paper is detected in 8, the transfer belt 7 is stopped after the transfer material conveyance ability by the fixing roll is lost. In this case, since the reduction of the sheet conveying ability by the fixing roll is determined in advance by a mechanical factor of pressure release, the stop of the transfer belt 7 may be delayed after a predetermined time has elapsed from the pressure release signal from the control device. Alternatively, the sheet conveying ability itself of the fixing roll, for example, the speed of the fixing roll may be detected, and the transfer belt may be stopped when the speed becomes a certain speed or less.

The positions of the preceding papers 17a and 17b, which are further preceding papers in FIG. 7, are detected by the paper sensors 75 and 72, respectively, and the fourth paper carrying unit 33 and the fifth paper carrying unit, respectively. The drive of the transport rolls inside the respective units is controlled so as not to stop between the 34th and sixth sheet transport units 35. Similarly to the preceding sheets 17a and 17b, the succeeding sheet 17f is also controlled by the sheet detection information of the sheet sensor and the driving of the conveying roll inside each unit so as not to stop between the third sheet conveying unit 32 and the other sheet conveying units. To do.

The control of the succeeding sheet 17e stretched between the transfer unit (first sheet conveying unit 30) detected by the sheet sensor 63 and the conveying unit (third sheet conveying unit 32) located upstream thereof is controlled by I have to think about it. First, as described above, even if the transfer belt 7 is stopped, it cannot be stretched between the first and third sheet conveying units 30 and 32. The entire succeeding paper 17e is pushed out to the transfer belt 7 side.

In this case, the succeeding paper sheet 17e is present in the vicinity of the suction device 14 in an uncontrollable posture, but when the first paper sheet transport unit 30 including the transfer device is pulled out toward the apparatus, the leading edge of the paper sheet is brought out. If the portion is adsorbed to the transfer belt 7, it can be pulled out. The second method of controlling the succeeding sheet of paper stretched between the first sheet conveying unit 30 and the third sheet conveying unit 32 is that the leading end of the sheet is the transfer belt 7.
This is the case when it is not adsorbed on.

In this case, when the first sheet conveying unit 30 is pulled out toward the apparatus, the sheet may be left in the apparatus, which is not a wise method. Therefore, for example, when it is determined from the paper detection information of the paper sensor 63 that the leading end of the paper is sufficiently attracted to the transfer belt 7 when the transfer belt 7 is stopped, the registration roll 1
When it is determined that the sheet is pushed toward the first sheet transport unit 30 side by 24 and is not sufficiently adsorbed, the transfer belt 7 is stopped and the registration roll 124
Is also stopped to minimize the amount of paper to be pushed into the first paper transport unit 30, and the third paper transport unit 32
Take a configuration that can be removed from the side.

The stop condition of the transfer belt, the photosensitive drum, the fixing device, and the conveying device when the winding jam occurs on the photosensitive drum has been described above. In this state, the leading end of the winding jammed paper is Since it is attracted to the drum by a fairly strong electrostatic attraction force, it cannot be removed only by pulling out the first paper transport unit including the transfer device. Therefore, the transfer belt and the photoconductor drum are temporarily stopped and then operated in the opposite directions.

Due to the stop condition, there is no paper between the transfer belt and the second paper transport unit including the fixing device which is a unit downstream thereof. Similarly, there is no paper between the transfer belt and the third paper transport unit including the registration roll, which is an upstream unit of the transfer belt. Therefore, the reverse operation of the transfer belt and the photosensitive drum may be an operation of returning the leading end of the wound jammed paper to the transfer belt position.

However, in the case where the stop condition of the fixing device 100 reaches the stop together with the pressure release, the stop of the transfer belt may be delayed after the stop of the photosensitive drum. In this case, the wound jammed paper is present between the transfer belt 7 and the cleaning member 15M of the photosensitive drum 2M in an uncontrollable posture. In order to return from this uncontrollable posture to a controllable posture even a little, it is possible to solve the problem by causing the transfer belt to reversely rotate at the time of reverse rotation because the transfer belt is stopped with a delay with respect to the photosensitive drum at the time of stop.

That is, the photosensitive drum is stopped at the moment when the occurrence of the winding jam is detected. However, the pressure release of the signal of the fixing device as emitted simultaneously, when the actual 300msec elapses until conveyance stop by the fixing device, stopping of the transfer belt should be delayed until the transport stopped by the fixing device. Therefore, the stop of the transfer belt is delayed by 300 msec with respect to the photoconductor drum, which affects the behavior of the jammed paper. However, after reversing only the transfer belt for 300 msec and removing the disturbed posture of the jammed jam paper by pulling the rear edge, the transfer belt and the photoconductor drum are reversed and the leading edge of the jammed jam paper is moved to the transfer belt position. Just go back up.

As means for returning the leading end of the wound jammed paper to the transfer belt position, the reverse rotation is performed by the reverse rotation time considering the relationship between the paper sensor and the transfer position, the time from the detection to the actual stop of the photosensitive drum, and the like. You may predict the amount. Further, the reverse rotation stop time may be calculated from the sheet detection information of sheet sensors arranged at various places in the apparatus. When the reversal is completed, the user can instruct the user to remove the paper existing in the device on the message board of the device, and the user can safely and simply remove the paper. Further, at the end of the work, the device can be returned to normal without any damage.

FIG. 8 is a conceptual diagram of functional blocks for executing the operation of the present embodiment. Reference numeral 80 is a central control unit (machine CPU) that controls the overall control of the image forming apparatus, and 81 is a paper transport unit and the like. Drive system CPU for driving,
A component CP 82 controls each member of the image forming system.
U and 83 are sensors CP for detecting the paper sensor and the like.
U, 83a is a timer circuit, 83b is a machine clock source,
83c is an image signal source, 83d is a signal from the registration sensor,
83e is a signal from the pop sensor, 83f is a sensor A
(A paper sensor in the unit), 83g a signal from a sensor B (paper sensor between units), 84 a drive control circuit for the paper transport unit, 84a a photoconductor drive motor, 84b a transfer belt drive motor, and 84c. Is a fixing unit drive motor, 85 is an output control circuit for supplying various image forming voltages, 85a is a developing bias, and 86 is a memory circuit for storing the sheet detection information of the sheet sensor. Reference numeral 14 is a transfer suction device, and 8 (Y, M, C, K) is a transfer device.

In the figure, the machine CPU 80 is a drive system CPU 81, a component CPU 82, and a sensor C.
The entire operation of the image forming apparatus is controlled via the PU 83.
The sensor CPU 83 recognizes a detection signal (registration sensor, pop sensor, sensor A, sensor B) indicating the presence / absence of a paper, which is detected by a paper sensor installed in each paper transport unit and between them, and is supplied to the machine CPU 80. It

At the same time, the status of each of the above-mentioned paper sensors, that is, the high level / low level (H / L) information, which is the paper detection information of each of the above-mentioned paper sensors, is stored in the memory circuit 86.
Remember. Then, the information regarding the presence / absence of the sheet of the sheet sensor, the information stored in the memory circuit 86, and the machine C.
The drive system CPU 81 controls the drive control circuit 8 based on the interval between sheets according to the print mode set in the PU 80.
The photosensitive member drive motor 84, the transfer belt drive motor 84b, and the fixing device drive motor 84c are controlled via 4 to adjust the position of the paper in each of the paper transport units described above.

The sheet conveying operation including the jam sheet position adjustment will be described in more detail below. FIG. 9 is an explanatory diagram of each CPU and each CPU of the image reading apparatus of this embodiment, and the flow of functions and operations thereof. In the figure,
For example, set an original as an image signal source, press the print button to read the original, perform predetermined image processing to form an image forming signal, and output the image forming condition to a required image forming member. The conveyance of the transfer material (paper) is started.

The sheet conveyance is started, the sheet is adsorbed onto the transfer belt and conveyed, and the sheet sensor in the sheet conveyance unit installed immediately downstream of the photosensitive drum of the first sheet conveyance unit 30 during the transfer operation. When the (pop sensor) detects that there is no paper, each CPU controls the drive of the drive system to adjust the jammed paper and the paper being conveyed to the above-mentioned easy-to-remove position. At the same time, the output of the component system is controlled to stop the supply of each voltage to the suction device, the fixing device, the developing device, and the like.

Then, the message board is instructed to remove the jammed paper, and the user is instructed to display the jammed paper carrying unit and take out the jammed paper. When the user removes the jammed paper and returns the paper transport unit to the normal state according to the instructions on the message board, a message to that effect is displayed on the message board.The user can press the print button again. You can continue printing.

10 to 14 are partial views of the flow chart for explaining an example of the operation when a winding jam occurs in this embodiment. The count time of the timer is just an example. In FIG. 10, a machine (image reading device)
When the registration roll is turned on (the registration sensor 63 of FIG. 4 detects the presence of paper) (S-1), the timer circuit (83 of FIG. 8) starts.
a) starts time counting.

After the cash register roll is turned on, the timer circuit becomes 161.
If the paper sensor 64 installed on the transfer drum 2Y in the first paper transport unit 30 does not detect the paper at the time when 0 ms is counted (S-2a) (S-3a), a pop jam occurs on the transfer drum 2Y. It is judged that it did (S
-4a). In addition, the timer circuit becomes 2 after the registration roll is turned on.
When the paper sensor 65 installed on the transfer drum 2M in the first paper transport unit 30 does not detect the paper at the time point when 830 ms is counted (S-2b) (S-3b), a pop jam occurs on the transfer drum 2M. It is judged that it did (S-4b).

Further, when the timer circuit counts 4060 ms after the registration roll is turned on (S-2c), the first
When the paper sensor 66 installed on the transfer drum 2C in the paper transport unit 30 does not detect the paper (S-3
In c), it is determined that pop jam has occurred in the transfer drum 2C (S-4c). Then, when the timer circuit counts 5280 ms since the registration roll is turned on (S-2
If the paper sensor 67 installed on the transfer drum 2K in the first paper transport unit 30 does not detect the paper in d) (S-3d), it is determined that a pop jam has occurred in the transfer drum 2K (S-). 4d).

In FIG. 11, when a pop jam occurs in any of the transfer drums, all drum motors in the image forming system are stopped (S-5a), and all image forming elements (components) are stopped (S-6). ). In the transfer belt system, depending on the presence / absence of paper detection by the paper sensor 68, after detection of 300 ms after detection, if there is no paper, the status of the paper sensor 68 (H / L)
Information is stored in the memory circuit 86 (FIG. 8), and the transfer belt motor is stopped (S-9).

In the fixing system, depending on whether or not the paper sensor 68 detects the paper, the fuser motor is stopped as it is if the paper is detected (S-11), and if the paper is not detected, the paper sensor 69 does not detect the paper ( The fixing unit motor is stopped at S-10) (S-11). In FIG. 12, when a pop jam occurs in any of the transfer drums in FIG. 10, it is determined in the registration roll system whether there is a condition matching “Table 1” 8S-12). Stop (S-15). If there is no matching condition, it is judged whether or not the paper sensor 63 detects the paper (S-13), and if there is, it counts 100 ms (S-14) and the register roll motor is stopped (S-15). .

Then, in the paper transport system (paper feed system), processing basically conforming to the normal jam removal specification is carried out (S-
16). However, the cash register roll sequence is based on the cash register roll described above. Further, in the case of “yes” in S-12 of the registration roll system sequence for judging the presence or absence of the condition matching “Table 1”, the registration motor is not driven to push the paper and the registration motor is immediately stopped, The motor is stopped (S-17).

In FIG. 13, (S-6) in FIG.
After (S-9) and (S-11), go to the (H / L) information of the paper sensor stored in the memory circuit 86,
When this information is L, all the drum motors are reversed as it is (S-20), and after counting A × 100 ms (S-
21) Stop all drum motors (S-22) and turn on all developing bias (S-23) A × 1
After counting 00 ms (S-24), all developing biases are turned off (S-25).

When the above information is H, after counting 300 ms (S-19), the process goes to (S-20). Then, at the same time as (S-18), the belt motor is rotated in the reverse direction (S
-26), go to the (H / L) information of the paper sensor stored in the memory circuit 86, and if this information is H, the belt motor after counting (A + 3) x 100 ms (S-28) Is stopped (S-30), and in the case of L, A × 100 ms is counted as it is (S-29) and the belt motor is stopped (S-30).

[0105] Note that "A" in the above is a value set individually, and it is possible to adjust when the deviation amount from the receipt of the start signal by the belt motor to the actual start of the belt motor is different, thereby causing a jam. The motor reverse rotation time required to return the sheet to a position where it can be easily removed is changed. In FIG. 14, stop of all drum motors (S-22), turn off of all developing bias (S-25), stop of belt motors (S-30).
Subsequently, it is determined whether or not the paper sensor 70 (FIG. 4) detects the paper (S-31), and the detection is present (H), that is, the paper exists between the second paper transport unit 31 and the third paper transport unit 32. If you are doing so, remove the paper from the left side of the machine.
Is displayed on the message board (S-32).

If there is no paper in S-31, an instruction for [remove paper from the belt maintenance door] is displayed on the message board (S-33), and the paper sensors 64 and 6 are detected.
It is determined whether or not paper is detected in 5, 66 and 67 (S-3
4) If there is detection, that is, if all the sheets in the first sheet conveying unit 30 are removed, and if there is no detection, an instruction for [normal jam removal] is displayed on the message board (S-35).

As described above, according to this embodiment, the jammed paper can be easily removed. The present invention is not limited to the so-called tandem type digital full-color copying machine as in the above embodiment, but can be applied to image forming apparatuses such as other types of copying machines.

[0108]

As described above, according to the present invention,
By determining the operation of each paper transport unit based on the paper position information within the paper transport unit or between the paper transport units, it is possible to prevent the wound jammed paper and the paper transported before and after it from damaging the device. In addition, it can be removed without causing breakage of the paper.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a schematic view of a main part for explaining a configuration around a sheet peeling unit and a transfer device of an embodiment of an image forming apparatus according to the present invention.

FIG. 3 is a schematic view of a main part for explaining a configuration of a sheet feeding unit for a transfer belt of an example of an image reading apparatus according to the present invention.

FIG. 4 is a schematic view illustrating the arrangement of a sheet detection sensor arranged in an embodiment of the image forming apparatus according to the present invention.

FIG. 5 is an explanatory diagram of a unit configuration when an embodiment of the image forming apparatus according to the present invention is considered as a composite body of a plurality of sheet conveying units.

FIG. 6 is an explanatory diagram of a specific example of the distance between the sheets according to the difference in the sheet size in the transport direction in the embodiment of the image forming apparatus according to the present invention.

FIG. 7 is an explanatory diagram of each sheet position when a sheet wrapping jam around the photosensitive drum occurs in an example of the image reading apparatus according to the present invention.

FIG. 8 is a conceptual diagram of functional blocks for executing the operation of the embodiment of the image reading apparatus according to the present invention.

FIG. 9 is an explanatory diagram of each CPU and each CPU of the image reading apparatus of one embodiment of the image reading apparatus according to the present invention, and the function and operation flow thereof.

FIG. 10 is a partial view of a flow chart explaining an example of an operation when a winding jam occurs in the embodiment of the image reading apparatus according to the present invention.

FIG. 11 is a partial view of a flow chart for explaining an example of an operation when a winding jam occurs in the embodiment of the image reading apparatus according to the present invention.

FIG. 12 is a partial view of a flow chart explaining an example of an operation when a winding jam occurs in the embodiment of the image reading apparatus according to the present invention.

FIG. 13 is a partial view of a flow chart explaining an example of an operation when a winding jam occurs in the embodiment of the image reading apparatus according to the present invention.

FIG. 14 is a partial view of a flow chart explaining an example of an operation when a winding jam occurs in the embodiment of the image reading apparatus according to the present invention.

[Explanation of symbols]

2Y, 2M, 2C, 2K ... Photosensitive drum, 3Y,
3M, 3C, 3K ... Charger, 4Y, 4M, 4C,
4K ... ・ Exposure beam, 5Y, 5M, 5C, 5K ...
..Developing device, 7 ... Transfer belt, 8Y. 8M. 8
C. 8K ··· Transfer charger, 9 ··· Drive roll,
10 ... ・ Following roll (peeling roll), 11, 12 ・
... Following roll, 13 ... Adsorption roll, 14 ...
... Adsorption charger, 15 ... Guide member, 15Y,
15M, 15C, 15K ... Cleaning member, 2
0 ... Peeling static eliminator, 21 ... Peeling nail, 23 ...
..Transfer belt inner static eliminator, 24 ... transfer belt outer static eliminator, 25-1, 25-2 ... transfer belt cleaning member, 100 ... fixing unit, 112-1, 1
12-2, 112-3 ... Paper feeding unit, 113.
... Double-sided transport path, 114-1, 114-2, 114-
3 ...- Paper transport rolls in paper feed unit, 116, 1
17 ... Paper transport roll in the third paper transport unit,
118 ... Ejection roll in fixing unit, 119 ...
..Paper discharge rolls, 120, 121, 122 ...
Paper transport rolls in the fourth paper transport unit, 124 ...
・ Paper delivery roll (resile roll), 125 ...
-Paper transport path confluence point 127 ... Reversal point (paper reverse traveling point) 129 ...- Movable paper guide (paper traveling path switching member).

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Fukada 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Zelocks Co., Ltd. (72) Inventor Takizo Sagawa 2274, Hongo Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) ) Inventor Ryoichi Tsuruoka 2274 Hongo, Ebina-shi, Kanagawa Fuji Zerox Co., Ltd. (56) Reference JP-A-7-53087 (JP, A) JP-A-6-135599 (JP, A) JP-A-60- 204547 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65H ⁷ /00-7/20 B65H 43/00-43/08 G03G 15/00

Claims (5)

(57) [Claims] 1. A first paper carrying unit for carrying paper.
And on the downstream side of the first paper transport unit in the paper transport direction.
Is placed and conveyed by the first sheet conveying unit
A plurality of paper transport units including at least a second paper transport unit for transporting the above-mentioned paper, an in-unit paper detection unit installed in the first paper transport unit, the first paper transport unit and the second paper transport unit An inter-unit sheet detection unit installed between the unit and a drive control unit for controlling the operation of the plurality of sheet transport units, wherein the drive control unit is a unit sheet installed in the first sheet transport unit. When the detection means detects a paper conveyance abnormality, the paper conveyance operation of the second paper conveyance unit is stopped based on the paper presence signal of the inter-unit paper detection means, and the paper conveyance of the second paper conveyance unit is stopped. The sheet transport operation of the first sheet transport unit is stopped according to the stop of the operation, and the sheet is transported by a predetermined distance in the direction opposite to the regular transport direction. A paper transport control method for an image forming apparatus, wherein a paper is easily removed from the first paper transport unit by executing a transport operation. 2. The first paper transport unit according to claim 1, wherein the first paper transport unit comprises an image transfer device including one or a plurality of photosensitive drums and a transfer belt, and the second paper transport unit discharges from the first paper transport unit. A sheet conveyance control method for an image forming apparatus, which is a fixing device that performs a fixing process on a transferred sheet. 3. A first paper transport unit that constitutes an image transfer device, a second paper transport unit that constitutes a fixing device that fixes the transferred paper discharged from the first paper transport unit, and the first paper. A plurality of paper transport units including at least a third paper transport unit that configures a paper transport device that transports the paper to the transport unit; an in-unit paper detection unit installed in the first paper transport unit; and the first paper transport An inter-unit sheet detection unit installed between the unit and the second sheet conveyance unit, and a drive control unit for controlling operations of the plurality of sheet conveyance units, wherein the drive control unit is provided in the first sheet conveyance unit. When the paper detection means in the unit installed in the unit detects a paper conveyance abnormality, the first paper conveyance unit and the second paper conveyance unit Stops the sheet conveyance operation of the second sheet conveying unit on the basis of the paper there the detection signal of the installed units between sheet detection means between said first depending on the stop of the sheet conveying operation of the second sheet conveying unit The sheet transport operation of the sheet transport unit is stopped, the first sheet transport unit is caused to perform the sheet transport operation in a direction opposite to the regular transport direction by a predetermined distance, and the first sheet transport unit and the first sheet transport unit are connected to each other. Removal of paper from the image transfer device by executing a carrying operation of pushing the paper into the first paper carrying unit when the inter-unit paper detecting means installed between the three paper carrying devices detects the existence of the paper. A paper conveyance control method for an image forming apparatus, which makes it easy. 4. The paper conveyance control of the image forming apparatus according to claim 2, wherein the paper detection means in the first paper conveyance unit is arranged downstream of the transfer device on the paper conveyance path. method. 5. The sheet of an image forming apparatus according to claim 2, wherein the sheet detecting means in the first sheet conveying unit is arranged upstream of a cleaning member provided around the photosensitive drum. Transport control method.