JPH0539143A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To avoid lowering of image quality and to improve the transport accuracy of recording paper sheets by eliminating generation of crease on recording paper sheets at the time of transporting the recording paper sheets at a registration roller portion. CONSTITUTION:An image forming apparatus comprises a registration roller 112 for transporting recording paper sheets to a transfer portion in synchronization with an image formed on a photoreceptor belt, an intermediate roller 110 for feeding recording paper sheets into the registration roller 112 and a paper sheet feed roller for separating and feeding recording paper sheets to the intermediate roller 110, wherein when the recording paper sheets are transported to the transfer portion by the registration roller 112, the intermediate roller 110 is stopped according to the size of the recording paper sheet to eliminate slackening of the recording paper sheet between the registration roller 112 and the intermediate roller 110.

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 such as a copying machine, a facsimile machine, a laser printer, etc., in which the conveyance (speed) of the recording paper from the paper feed section to the registration roller section can be controlled well. The present invention relates to an image forming apparatus that eliminates wrinkles.

[0002]

2. Description of the Related Art In a conventional image forming apparatus such as a copying machine, a facsimile machine, a laser printer, etc., when a recording paper is conveyed to a transfer section for transferring an image formed on a photoconductor, a registration roller is used. The conveyance speed of the intermediate roller or the paper feed roller that feeds the recording paper (the conveyance speed of the registration roller <the conveyance speed of the paper feed roller or the intermediate roller was used) was controlled, or the predetermined conveyance timing (the leading edge of the recording paper was registered (Delaying the time from the arrival at the roller until the start) is taken, and the conveyance process is executed while forming a certain slack on the recording paper when the registration roller is restarted.

[0003]

However, in the image forming apparatus conveying method as described above, when the recording sheet is conveyed from the sheet feeding section to the registration roller, the sheet feeding roller or the intermediate roller conveys the recording sheet. Since the speed is set to be slightly high, the slack of the recording paper in front of the registration rollers increases, and wrinkles are generated on the recording paper. In particular, when a long recording paper is used, such a problem is likely to occur and an image is formed on a wrinkled portion, so that the image quality is deteriorated.
Further, when a large wrinkle is generated on the recording paper, it causes catching or meandering in the conveying path, which causes a conveyance failure such as a jam, and lowers the conveying accuracy of the recording paper.

The present invention has been made in view of the above, and eliminates the occurrence of wrinkles when the recording paper is conveyed by the registration roller portion, avoids the deterioration of the image quality, and improves the conveyance accuracy of the recording paper. The purpose is to improve.

[0005]

In order to achieve the above object, the present invention provides a conveying means for conveying a recording sheet to a transfer section in synchronization with an image formed on a photosensitive member, and a conveying means for conveying the recording sheet. In an image forming apparatus having an intermediate conveying unit for feeding the recording sheet and a sheet feeding unit for separating and feeding the recording sheet to the intermediate conveying unit, recording is performed while the recording sheet is conveyed to the transfer section by the conveying unit. (EN) An image forming apparatus provided with a control means for stopping the intermediate conveying means according to the size of the paper and for removing the slack of the recording paper between the conveying means and the intermediate conveying means. ..

Further, a registration roller that conveys the recording paper to the transfer portion in synchronization with the image formed on the photosensitive member, an intermediate roller that relays the recording paper to the registration roller, and sends the recording paper to the intermediate roller. A sheet feeding roller for separating and feeding the sheet, an intermediate sensor arranged immediately before the intermediate roller for detecting the conveyance timing of the recording sheet, and a register arranged immediately before the registration roller for detecting the leading edge of the recording sheet. In an image forming apparatus including a sensor and a control unit that controls the drive timing of the registration roller, the intermediate roller, and the paper feed roller based on signals from the intermediate sensor and the registration sensor, recording paper is transferred by the registration roller. While being conveyed to the sheet, the intermediate roller is stopped according to the size of the recording paper so that it is placed between the registration roller and the intermediate roller. It is desirable to remove the slack of the recording paper that.

Further, a conveying means for conveying the recording paper to the transfer portion in synchronization with the image formed on the photoconductor, an intermediate conveying means for feeding the recording paper to the conveying means, and a recording paper for the intermediate conveying means. In an image forming apparatus having a sheet feeding unit for separating and feeding, the recording sheet conveying speed of the intermediate conveying unit is controlled at high speed until the recording sheet is conveyed from the sheet feeding unit to the conveying unit, and the conveying unit performs recording. An image forming apparatus is provided which is controlled at a low speed while a sheet is conveyed to a transfer unit.

[0008]

In the image forming apparatus according to the present invention, when the recording sheet is being conveyed to the transfer section by the conveying means, the intermediate conveying means is stopped in accordance with the size of the recording sheet so that the conveying means and the intermediate conveying means are separated from each other. The control is performed to remove the slack of the recording paper during the interval.

Further, the recording paper conveying speed of the intermediate conveying means is
High speed control is performed until the recording paper is fed from the paper feeding means to the transport means, and low speed control is performed while the transport means is transporting the recording paper to the transfer section.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a configuration of a laser printer as an example of an image forming apparatus according to the present invention. 10
Reference numeral 1 is a laser printer main body that forms an image by a copying process, 102 is a polygon motor that rotates a polygon mirror 103 at a high speed, 103 is a polygon mirror that has a mirror on the side surface of a regular polyhedron and that rotates at a high speed to scan a laser beam,
Reflection mirrors 104 and 105 guide the laser beam scanned by the polygon mirror 103 to the photoconductor belt 106.
Reference numeral 106 is a photoconductor belt that forms an electrostatic latent image by a copying process.

Further, 107 is a paper feed tray for accommodating a plurality of recording papers, 108 is a paper feed roller for feeding the recording papers, 1
Reference numeral 09 is a friction pad that faces the paper feed roller 108 and separates the recording paper, 110 is an intermediate roller that conveys the recording paper sent from the paper feed roller 108 to the registration roller 112, and 111 detects the leading end position of the recording paper. Intermediate roller 1
An intermediate sensor for outputting a conveyance timing signal of 10, 11
Reference numeral 2 is a registration roller that conveys the recording paper while keeping timing with the image on the photosensitive belt 106, and 113 is a registration sensor that detects the leading end position of the recording paper.

Further, 114 is a charging charger for uniformly corona-discharging the surface of the photoconductor belt 106, 115 is a developing unit for accommodating toner and performing a developing process by a developing process, 116 is supplying toner to the developing unit 115. A toner cartridge 117, a transfer charger that performs a transfer process by corona discharge, and 118 a photosensitive belt 10.
Cleaning blade for cleaning 6 surfaces, 1
Reference numeral 19 denotes a cleaning unit including a cleaning blade 118, a toner recovery tank, and the like. Reference numeral 120 denotes a charge eliminating lamp (Q) that removes residual charges on the photosensitive belt 106 by irradiating light after the cleaning process.
L).

Further, 121 is a fixing roller which has a heater built in inside thereof, the surface of which is made of a heat-resistant and releasable material and which is controlled to rotate at a predetermined temperature, and 122 is a fixing roller 121.
A pressing roller that rotates in a state of being urged with a predetermined pressure in opposition to the reference numeral 123 is a discharging roller for discharging the recording paper after the fixing processing (during face-up discharging), or a discharging roller for sending to a conveying roller 124, 124 Is a relay conveyance roller that relays the recording paper sent by the paper ejection roller 123 to the next conveyance roller 125, and 125 is a paper ejection roller that ejects the recording paper during face-down paper ejection.

Further, 126 is a paper feed roller 108, an intermediate roller 110, a registration roller 112, and a fixing roller 12.
1, a discharge roller 123, a conveyance roller 124, a discharge roller 125, and the like, which are all-conveyance drive motors that are drive sources for the rollers that convey the recording paper. Each roller is drivingly connected by a timing belt or the like. A clutch and a solenoid (not shown) for controlling start / stop are arranged on the drive shaft portion.

Numeral 127 is an alternative construction of the above-mentioned drive motor 126, which is arranged separately from the drive motor 126,
It is a conveyance motor configured by a stepping motor that drives the paper feed roller 108 and the intermediate roller 110.

The operation of the laser printer configured as described above will be described. The laser beam modulated according to the written image data is rotated at a high speed and at a constant speed, and the polygon mirror 103 and the reflection mirrors 104 and 10 are rotated.
The light beam is deflected by the beam No. 5 and is irradiated onto the photoconductor belt 106.
On the other hand, prior to this, since the surface of the photoconductor belt 106 is uniformly charged by the charging charger 114, an electrostatic latent image corresponding to the image data is formed on the photoconductor belt 106 due to the potential distribution. The formed electrostatic latent image is visualized by the toner in the developing unit 115.

On the other hand, a sheet feeding solenoid (not shown,
When the sheet feeding SOL) is turned on, the clutch operates to transmit the rotational force to the sheet feeding roller 108. Then, the recording paper stored in the paper feed tray 107 is fed one by one by the paper feed roller 108 and the friction pad 109. Next, the intermediate roller solenoid (not shown, hereinafter referred to as intermediate SOL) is turned on to operate the clutch, and the rotation of the intermediate roller 110 causes the recording paper to be relayed to the intermediate roller 110 and reach the registration roller 112. At this time, a registration solenoid (not shown, hereinafter, at a timing when the leading edge position of the recording paper is detected by the registration sensor 113).
The resist SOL) is turned on, the clutch is operated, and the resist roller 112 is rotated. The registration roller 112 aligns the toner image on the photosensitive belt 106 and sends the recording paper to the transfer portion.

The image on the photosensitive belt 106 is transferred onto this recording paper by the corona discharge of the transfer charger 117. The recording paper on which the toner image has been transferred is sent to the nip between the fixing roller 121 and the pressure roller 122, which are controlled at a predetermined temperature, and is subjected to the fixing process, and then discharged outside the machine.
At this time, when the face-up paper ejection is selected, the paper is ejected straight by the paper ejection roller 123, and when the face-down paper ejection is selected, the paper ejection roller 123, the relay conveyance roller 124, The sheet is discharged onto the laser printer 101 by the sheet discharge roller 125.

In the above, when the carry motor 127 is used, the structure of the paper feed SOL and the clutch and the intermediate SOL and the clutch is eliminated, and the carry motor 127 is turned on.
By the drive transmission by turning on / off, the paper feed roller 108 and the intermediate roller 110 are started / stopped.

Further, the photosensitive belt 106 after the transfer processing
The residual toner is removed by the cooling blade 118 of the cleaning unit 119, and the residual toner is stored in the recovery tank. Further, the charge removal lamp 120 removes the residual charge after the cleaning process, and stands by until the next image formation command is input.

FIG. 2 is a timing chart showing an operation example of the recording paper conveyance control according to the present invention. Figure 2
(A) is a paper feed S driven by the drive of the all-conveyance drive motor 126.
OL and clutch, intermediate SOL and clutch, resist SO
2B is a timing chart in the case of controlling via L and the clutch, and FIG. 2B is a timing chart in the case of controlling the transport speed (high speed / low speed) of the intermediate roller 110 by the drive transmission by ON / OFF of the transport motor 127. is there.

In FIG. 2, t ₁ is the time from when the leading edge of the recording sheet turns on the registration sensor 113 to when the conveyance operation of the recording sheet by the intermediate roller 110 is stopped, and the recording sheet enters the nip portion of the registration roller 112. Is fed to form a slack between the registration roller 112 and the intermediate roller 110 due to excessive feeding of the recording paper, and skew correction (oblique feeding of the recording paper is brought into contact with the nip of the registration roller 112 to be corrected) is executed. This is the slack forming time.
Further, t ₂ indicates the start of feeding the recording paper to the transfer charger 117 by the registration roller 112, and t ₃ is a temporary intermediate for preventing excessive slack of the recording paper during conveyance of the recording paper by the registration roller 112. Roller 11
It shows the time when the transport of 0 is stopped.

FIG. 3 is a flow chart showing an example of recording paper conveyance control according to the present invention.
FIG. 2 shows an example in which the drive transmission of FIG. 2 is started / stopped by the clutch of each roller and each SOL.
It is an operation example shown in the timing chart of (a).

In the figure, by the start of image formation,
First, a paper feeding SOL (not shown) and an intermediate SOL (not shown)
Is turned on (S301), the paper feed roller 108 and the intermediate roller 110 are rotated, and the recording paper in the paper feed tray 107 is fed. The ON state of the intermediate sensor 111 is confirmed by the movement of the recording sheet (S302). When the intermediate sensor 111 is ON, the sheet feeding SOL is turned OFF (S303), and the rotation of the sheet feeding roller 108 is stopped.

Next, the leading edge of the recording paper is the registration sensor 11
It is confirmed whether or not the number reaches 3 and the registration sensor 113 is turned on (S304). When the registration sensor 113 is turned on by the movement of the recording paper, the intermediate SOL is turned off after a lapse of a predetermined time from the time of turning on (S305), and the intermediate roller 110 is stopped. Next, the timing for synchronizing the toner image formed on the photosensitive belt 106 with the recording sheet (start of transfer conveyance) is confirmed (S306), and if it is the synchronizing timing, the resist SOL and the intermediate SOL are turned on (S307). , Registration roller 112 and intermediate roller 11
0 is restarted.

Next, it is confirmed that the intermediate sensor 111 is OFF (S308). If the intermediate sensor 111 is ON,
ON / OFF control of the intermediate SOL (the part of the timing chart t ₃ shown in FIG. 2) is performed (S309), and the intermediate sensor 1
If 11 is OFF, the intermediate SOL is turned OFF (S3
10) The rotation of the intermediate roller 110 is stopped. Next, the ON / OFF state of the registration sensor 113 is confirmed (S3
11) If the registration sensor 113 is OFF, the registration SOL is turned OFF (S312), and the registration roller 1
The rotation of 12 is stopped.

The image formation on one sheet of recording paper is completed by the above operation. At this time, it is confirmed whether or not there is a next recording instruction (S313), and if there is a next recording instruction, step 30 is performed.
Returning to step 1, the same operation is executed. On the contrary, if there is no next recording instruction, the paper discharge is confirmed (S314), and if the paper is discharged, the all-conveyance drive motor 126 is turned off (S315).

As described above, the registration roller 11
Since excessive slackening of the recording paper in two sets is appropriately suppressed by the start / stop control of the intermediate roller 110, wrinkling of the recording paper due to excessive slack can be eliminated.

FIG. 4 is a flow chart showing an example of recording paper conveyance control according to the present invention, in which the conveyance motor 127 is used to perform high speed / low speed control and stop control of the paper feed roller 108 and the intermediate roller 110. FIG. 2 (b)
6 is an operation example shown in the timing chart of FIG.

In the figure, by the start of image formation,
First, the transport motor 127 is driven at high speed (S40
1) rotate the paper feed roller 108 and the intermediate roller 110,
The recording paper in the paper feed tray 107 is fed. The ON state of the intermediate sensor 111 is confirmed by moving the recording paper (S402),
When the intermediate sensor 111 is ON, the paper feeding SOL is turned OFF (S403) and the rotation of the paper feeding roller 108 is stopped.

Next, the leading edge of the recording paper is the registration sensor 11
It is confirmed whether or not the number reaches 3 and the registration sensor 113 is turned on (S404). When the registration sensor 113 is turned on by the movement of the recording paper, the carry motor 127 is stopped (S405). Next, the timing for synchronizing the toner image formed on the photosensitive belt 106 with the recording sheet (starting transfer conveyance) is confirmed (S406), and if it is the synchronization timing, the conveyance motor 127 is driven at a low speed (S40).
7) The intermediate roller 110 is rotated at a low speed, and the rotation of the registration roller 112 is restarted.

Next, it is confirmed that the intermediate sensor 111 is OFF (S408), and if the intermediate sensor 111 is ON,
As it is, the recording paper is controlled to be conveyed at low speed (S409), and if the intermediate sensor 111 is OFF, the conveyance motor 127 is stopped (S410) and the rotation of the intermediate roller 110 is stopped. Next, the on / off state of the registration sensor 113 is confirmed (S411), and the registration sensor 113 is turned off.
If so, the rotation of the registration roller 112 is stopped (S
412).

By the above operation, image formation on one sheet of recording paper is completed. At this time, it is confirmed whether or not there is next recording (S413), and if there is a next recording instruction, step 401
Then, the same operation is executed, and conversely, if there is no next recording instruction, the paper discharge is confirmed (S414), and if the paper is discharged, the carry motor 127 is turned off (S415).

As described above, by controlling the carry motor 127 at a high speed during the paper feeding operation, the margin for the paper feeding failure caused by the slip or the like becomes large, and the stable paper feeding can be performed. Further, during the recording operation, the process speed and the transport speed are controlled to be substantially constant,
Excessive slack in the recording paper at the registration roller 112 is eliminated, and stable image formation is realized.

Although the embodiment of the present invention has been described with reference to the configuration example of the laser printer, the present invention is not limited to this and can be applied to a copying machine, a facsimile, and an apparatus having a paper conveying means similar thereto. Further, although the intermediate roller 110 is configured in this embodiment, the intermediate roller 110 is omitted when the path is short or the path is long due to the transport path between the sheet feeding unit and the transfer unit. The intermediate roller 110 may be additionally provided to have a configuration suitable for the apparatus.

[0036]

As described above, according to the image forming apparatus of the present invention, when the recording sheet is conveyed to the transfer portion by the conveying means, the intermediate conveying means is stopped according to the size of the recording sheet. Control for removing the slack of the recording paper between the conveying means and the intermediate conveying means, and the recording paper conveying speed of the intermediate conveying means is controlled at high speed until the recording paper is fed from the paper feeding means to the conveying means. However, since the conveying unit controls the recording paper at a low speed while conveying the recording paper to the transfer unit, the occurrence of wrinkles when the recording paper is conveyed by the registration roller unit is eliminated,
It is possible to avoid deterioration of image quality and improve the conveyance accuracy of the recording paper.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a laser printer used as an example of an image forming apparatus according to the present invention.

FIG. 2 is a timing chart showing an operation example of recording paper conveyance control in the image forming apparatus according to the present invention.

FIG. 3 is a flowchart showing an example of recording paper conveyance control operation of the image forming apparatus according to the present invention.

FIG. 4 is a flowchart showing an example of a recording paper conveyance control operation of the image forming apparatus according to the present invention.

[Explanation of symbols]

106 Photoreceptor Belt 108 Paper Feed Roller 110 Intermediate Roller 111 Intermediate Sensor 112 Registration Roller 113 Registration Sensor 126 All Conveyance Drive Motor 127 Conveyance Motor

Claims (3)

[Claims] 1. A conveying means for conveying a recording sheet to a transfer section in synchronization with an image formed on a photoconductor, an intermediate conveying means for feeding the recording sheet to the conveying means, and a recording sheet for the intermediate conveying means. In an image forming apparatus having a sheet feeding unit for separating and feeding, while the recording sheet is being conveyed to the transfer unit by the conveying unit, the intermediate conveying unit is stopped according to the size of the recording sheet, and the conveyance is performed. An image forming apparatus comprising: a control unit that controls the slack of the recording paper between the unit and the intermediate conveying unit. 2. A registration roller that conveys a recording sheet to a transfer section in synchronization with an image formed on a photoconductor, an intermediate roller that relays the recording sheet to the registration roller, and sends the recording sheet to the intermediate roller. A sheet feeding roller for separating and feeding the sheet, an intermediate sensor arranged immediately before the intermediate roller for detecting the conveyance timing of the recording sheet, and a register arranged immediately before the registration roller for detecting the leading edge of the recording sheet. In an image forming apparatus including a sensor and a control unit that controls the drive timing of the registration roller, the intermediate roller, and the paper feed roller based on signals from the intermediate sensor and the registration sensor, recording paper is transferred by the registration roller. When the sheet is being conveyed to the sheet, the intermediate roller is stopped according to the size of the recording paper, and the recording between the registration roller and the intermediate roller is stopped. The image forming apparatus according to claim 1, wherein the slack of the recording paper is removed. 3. A conveying unit that conveys the recording sheet to a transfer unit in synchronization with an image formed on a photoconductor, an intermediate conveying unit that feeds the recording sheet to the conveying unit, and a recording sheet to the intermediate conveying unit. In an image forming apparatus having a sheet feeding unit for separating and feeding, the recording sheet conveying speed of the intermediate conveying unit is controlled at high speed until the recording sheet is conveyed from the sheet feeding unit to the conveying unit, and the conveying unit performs recording. An image forming apparatus that is controlled at a low speed while the paper is being conveyed to a transfer unit.