JP2001312150A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of ejecting transfer paper to the outside without secondarily transferring an image by driving a carrying means when the transfer paper comes to the position of a resist roller with a delay. SOLUTION: When a paper detection means 57 at a position just before the resist roller 12 detects the position of the leading edge of the transfer paper 15 after a driving command signal gets to the resist roller 12 from a control means 7, the transfer paper 15 is carried and ejected to the outside without secondarily transferring the image to the transfer paper 15, so that the transfer paper 15 is ejected to the outside by driving paper carrying means 3, 22 to 26 even when paper jamming does not occur. Therefore, toner and the transfer paper 15 are prevented from being wasted due to a transfer error that the image is secondarily transferred to the transfer paper 15 in a state where it is positionally deviated.

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, and more particularly, to a countermeasure for a trouble during transfer of a transfer sheet.

[0002]

2. Description of the Related Art Conventional techniques include, for example,
There is a jam detection device described in Japanese Patent No. 38655.
This conventional jam detection device stores the jam position when a paper jam occurs, detects whether or not transfer paper is present in a passage when power feeding is resumed, and detects when the transfer paper is detected. If the detected transfer paper is present at the jam position stored in the storage means, the control at the time of paper jam detection is continued, and the detected transfer paper is stored in a position other than the jam position stored in the storage means. If it exists in
By controlling the paper transport means to drive and discharge the transfer paper, a jam detection device capable of performing an efficient processing without the risk of damaging a mechanical device in the processing of a paper jam. It is described in the above-mentioned publication that the object is to provide the above.

[Problems to be solved by the invention]

On the other hand, in a color image forming apparatus, for example, a registration roller determines that multiple transfer to an intermediate transfer drum has been completed based on a detection signal from a reference position sensor for detecting a reference position of a photoconductor, and then sets a registration roller. Since the transfer of the transfer sheet is started at the timing of the start position of the transfer sheet, the start position of the transfer sheet is compared with the case where the start position of the transfer sheet is set only by the registration roller as in a monochrome image forming apparatus. If the transfer paper is not at the position of the registration roller before the drive command signal is sent from the controller to the registration roller, the position that is shifted from the normal transfer position of the transfer paper The color toner image is secondarily transferred to the printer, causing a transfer error and causing toner and transfer paper Waste is generated.

The fact that such a transfer sheet arrives at the position of the registration roller later than a predetermined time does not necessarily occur only in the case of a sheet jam. If the transfer paper comes to the position of the registration roller later than a predetermined time due to slippage between the roller of the paper conveyance means and the transfer paper, a decrease in the rotation speed of the roller of the paper conveyance means, etc. In the case of the described conventional jam detection device, the transfer sheet cannot be discharged by driving the sheet conveying means.

Accordingly, in view of the above problems, the present invention provides a method for driving a transfer sheet when a transfer sheet arrives at a position of a registration roller later than a predetermined time without performing secondary transfer to the transfer sheet. An object of the present invention is to provide an image forming apparatus capable of discharging a transfer sheet to the outside.

[0006]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention comprises a photosensitive member for forming an electrostatic latent image on a peripheral surface, and a toner image formed by developing the electrostatic latent image. Developing means for forming, a reference position detecting means for detecting a reference position of the photoreceptor, an intermediate transfer body for primary transfer of a toner image from the photoreceptor, and a transfer sheet passing between the intermediate transfer body. A secondary transfer means for secondary-transferring the toner image of the intermediate transfer body, and a registration roller for conveying the transfer sheet at the timing of the secondary transfer by the secondary transfer means,
Paper transport means for transporting the transfer paper along the transport path, paper detection means for detecting the transfer paper at each position of the transport path, and control means for controlling each component, the control roller from the control means When the paper detecting means immediately before the registration roller detects the leading position of the transfer sheet after the drive command signal is received, the transfer sheet is transferred without the secondary transfer by the secondary transfer means. And discharge it to the outside.

According to the image forming apparatus having such a configuration,
When the paper detection means immediately before the registration roller detects the leading position of the transfer sheet after the drive command signal is sent from the control means to the registration roller, the sheet is transported to the transfer sheet without secondary transfer and transferred to the outside. Since the sheet is ejected, the transfer sheet can be ejected to the outside by driving the sheet conveying means without causing a sheet jam. For this reason, it is possible to prevent waste of toner and transfer paper from occurring due to a transfer error in which the image is shifted to the transfer paper and the image is secondarily transferred.

[0008]

Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 3
FIG. 1 is a diagram referred to for describing an embodiment of an image forming apparatus according to the present invention.

FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention. The color image forming apparatus includes a photosensitive drum 1 (photosensitive body), four developing devices 4a to 4d (developing means) for each color, and a photosensitive drum 1 for generating a reference position signal in the sub-scanning direction. Reflective photosensor 6 (reference position detection means) for reading reference position marks formed on the outer peripheral surface of body drum 1, intermediate transfer drum 8 (intermediate transfer body), secondary transfer roller 9 (secondary transfer means) , A separation charger 10 and a pair of registration rollers 12.

In such a color image forming apparatus,
The photosensitive surface of the photosensitive drum 1 is charged by a charging device (not shown), and the charged photosensitive surface of the photosensitive drum 1 is subjected to a laser light unit (not shown) based on image information based on image information. ) To form an electrostatic latent image.

The electrostatic latent image on the photosensitive drum 1 is subjected to, for example, magenta (red), yellow (yellow), cyan (blue) color toner and black (black) toner by four developing devices 4a to 4d. Are sequentially developed using. At this time, the photosensor 6 generates a reference position signal of the photosensitive drum 1 in the sub-scanning direction, and based on this signal, the toner images of the respective colors are developed so as not to be shifted from each other.

At each development, the toner image is primary-transferred onto the surface of the intermediate transfer drum 8 rotating in contact with the photosensitive drum 1 in order, and finally, the four colors are transferred onto the intermediate transfer drum 8. Are transferred in a multiplex manner.

The transfer paper 15 fed between the transfer roller 9 and the intermediate transfer drum 8 on which the color toner image is multi-transferred onto the surface from the photosensitive drum 1 is transferred by the transfer roller 9. By charging
The multiple color toner images on the intermediate transfer drum 8 are secondarily transferred.

After the transfer paper 15 on which the color toner image has been secondarily transferred passes between the transfer roller 9 and the intermediate transfer drum 8, the separation charger 10 removes the charge applied during the secondary transfer. Intermediate transfer drum 8
, And is fed leftward in the figure by the conveyor belt 3, and is fixed as a full-color image by the fixing device 5.

As shown in FIG. 2, the photo sensor 6 and the fourth paper sensor 57 are connected to a controller 7.
(Control means), and the controller 7 controls the transfer roller 9, the registration roller 12, the transport belt 3, the transport rollers 22, 23,
24, a signal is output to paper transport means such as discharge rollers 25 and 26.

The above configuration is provided in the main unit 20, and an auxiliary unit 30 is disposed below the main unit 20. A paper feed unit 30a is provided below the accessory unit 30, and a reverse paper feed unit 30b is provided above the accessory unit 30.

In the main unit 20, the manual feed tray 1
The transfer paper 15 from the transfer roller 7 passes through a feed roller 19 and a registration roller 12, and after the color toner image is secondarily transferred by the intermediate transfer drum 8 and the transfer roller 9, the transfer belt 3, the fixing device 5, the transfer roller 22 , 23,2
4. In addition to being discharged onto the tray 27 in the direction of arrow A via the discharge roller 25 so as to be in a face-down state, from the transport roller 22 via the discharge roller 26 in the direction of arrow B,
The sheet is discharged onto the tray 28 so as to be in a face-up state.

In the main unit 20 and the auxiliary unit 30, the transfer paper 15 from the paper supply unit 30a is sent to the registration roller 12 via the pickup roller 32, the conveyance rollers 34 and 35, the relay roller 36, and the conveyance roller 37.

The transfer sheet 15 from the transport roller 22 after the secondary transfer by the intermediate transfer drum 8 and the transfer roller 9 and further fixing by the fixing device 5 is discharged in the A and B directions. , Are sent to the accessory unit 30 and are transported by rollers 41, 42, 43, 44, 45,
After being sent to the reversing sheet feeding unit 30b and turned upside down by 46, the conveying rollers 45 and 46 rotate in the reverse direction to send the transfer paper 15 to the relay roller 36 via the conveying roller 47, and then the conveying roller 37 and the resist Secondary transfer can be performed on the back surface of the transfer paper 15 by the intermediate transfer drum 8 and the transfer roller 9 via the roller 12. The rollers and the conveyor belt 3 constitute a paper conveying unit.

Several paper sensors (paper detection means) are arranged and provided in the middle of the paper transport path. That is, the first paper sensor 51 in front of the transport roller 35,
The second paper sensor 53 before the relay roller 36, the third paper sensor 55 before the conveyance roller 37, the fourth paper sensor 57 before the registration roller 12, the conveyance roller 24
, The sixth paper sensor 61 behind the discharge roller 25, and the seventh paper sensor 61 before the discharge roller 26.
Paper sensor 63, conveyance roller 22 of main unit 20
Eighth and ninth paper sensors 65 and 67 between the transport rollers 41 of the reversing paper feed unit 30b and a tenth paper sensor 69 between the transport rollers 43 and 44 are provided.

Such paper sensors 51, 53, 5
5, 57, 59, 61, 63, 65, 67, and 69 can detect the current transport position of the transfer paper 15 and the jam position of the transfer paper 15 at the time of paper jam (paper jam).

Further, based on a reference position detection signal in the sub-scanning direction of the photosensitive drum 1 input to the controller 7 by the photo sensor 6, the color toner images on the intermediate transfer drum 8 are kept on the intermediate transfer drum 8 without any deviation. When the registration roller 12 is determined to have formed, the registration roller 12 immediately conveys the standby transfer paper 15, and the transfer roller 9 transfers the color toner image to the transfer paper 15 secondarily.

However, due to double feeding of the transfer paper 15, slippage between the roller of the paper transport means and the transfer paper, reduction of the nip amount due to wear of the roller of the paper transport means, etc., the registration roller 12 at the standby position is located. Transfer paper 15
However, when the drive command signal from the controller 7 comes later than it arrives at the registration roller 12, if the transfer paper 15 is transported as it is and the secondary transfer is performed by the transfer roller 9, the color toner on the intermediate transfer drum 8 is The image is deviated from the proper transfer position of the transfer paper 15 and is secondarily transferred.

In order to prevent this, in the present embodiment, as shown in FIG. 3, the fourth sheet sensor 57 detects that the transfer sheet 15 has arrived at the position of the registration roller 12 later than a predetermined time. Is detected (YES in step S3 in the same figure), the transfer roller 9 is separated from the intermediate transfer drum 8 and is conveyed to the transfer paper 15 without performing the secondary transfer (step S5 in the same figure). (Step S4 in the figure), the transfer paper 15 is simply discharged from the transport roller 22 in the direction of the arrow A or B (Step S6 in the figure).

For this reason, even if a paper jam does not occur,
If the transfer paper 15 is delayed from the position of the registration roller 12 by a predetermined time, the paper transport means can be driven to discharge the transfer paper 15 to the outside. It is possible to prevent the paper 15 from being wasted.

In the above embodiment, when the transfer sheet 15 arrives at the position of the registration roller 12 with a delay, the transfer sheet 15 is conveyed without secondary transfer and discharged to the outside. The transfer paper 15 is wound around the intermediate transfer drum 8 when it comes to the position of the registration roller 12, and the unit including the intermediate transfer drum 8 is later pulled out to remove the wound transfer paper 15 by hand. You may make it.

In the above embodiment, the case where the present invention is applied to a color image forming apparatus has been described. However, the present invention is not limited to a color image forming apparatus. And any other types of image forming apparatuses.

[0028]

As described above, according to the image forming apparatus of the present invention, after the drive command signal is sent from the control unit to the registration roller, the paper detection unit immediately before the registration roller determines the leading position of the transfer sheet. When a sheet is detected, the sheet is conveyed without secondary transfer to the transfer sheet and ejected to the outside.Therefore, the sheet conveying means can be driven to eject the transfer sheet to the outside even if a sheet jam does not occur. it can. For this reason, it is possible to prevent waste of toner and transfer paper from occurring due to a transfer error in which the image is shifted to the transfer paper and the image is secondarily transferred.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a main unit 20 and an attachment unit 30 of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a main part of the color image forming apparatus in FIG. 1;

FIG. 3 is a flowchart illustrating a main part of an operation procedure of the color image forming apparatus in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 3 Conveyor belt 4a-4d Developing device 5 Fixing device 6 Photosensor 7 Controller 8 Intermediate transfer drum 9 Secondary transfer roller 10 Separation charger 12 Registration roller 15 Transfer paper 17 Manual feed tray 19 Feed roller 20 Main unit 30 Attached unit 30a Paper feed unit 30b Reverse paper feed unit 22, 23, 24 Transport roller 25, 26 Discharge roller 27 Tray unit 28 Tray 32 Pickup roller 34, 35 Transport roller 36 Relay roller 37 Transport roller 41, 42, 43, 44, 45, 46, 47 Conveying rollers 51 First paper sensor 53 Second paper sensor 55 Third paper sensor 57 Fourth paper sensor 59 Fifth paper sensor 61 Sixth paper sensor 63 Seventh paper sensor 65 Eighth paper sensorー 67 9th paper sensor 69 10th paper sensor

Claims (2)

[Claims] A photosensitive member that forms an electrostatic latent image on a peripheral surface; a developing unit that develops the electrostatic latent image to form a toner image; and a reference position detecting unit that detects a reference position of the photosensitive member. An intermediate transfer member on which a toner image is primarily transferred from the photoreceptor; a secondary transfer unit for secondary-transferring a toner image of the intermediate transfer member onto transfer paper passing between the intermediate transfer member; A registration roller that conveys the transfer paper at the timing of the secondary transfer by the transfer unit; a paper conveyance unit that conveys the transfer paper along the conveyance path; and a paper detection unit that detects the transfer paper at each position of the conveyance path And control means for controlling each component.When the paper detection means immediately before the registration roller detects the leading position of the transfer sheet after a drive command signal is sent to the registration roller from the control means, This transcription An image forming apparatus, wherein a sheet is conveyed by the paper conveying means and discharged to the outside without being secondarily transferred by the secondary transfer means. 2. A photosensitive member for forming an electrostatic latent image on a peripheral surface, a developing unit for developing the electrostatic latent image to form a toner image, and a reference position detecting unit for detecting a reference position of the photosensitive member An intermediate transfer member on which a toner image is primarily transferred from the photoreceptor; a secondary transfer unit for secondary-transferring a toner image of the intermediate transfer member onto transfer paper passing between the intermediate transfer member; A registration roller that conveys the transfer paper at the timing of the secondary transfer by the transfer unit; a paper conveyance unit that conveys the transfer paper along the conveyance path; and a paper detection unit that detects the transfer paper at each position of the conveyance path And control means for controlling each component.When the paper detection means immediately before the registration roller detects the leading position of the transfer sheet after a drive command signal is sent to the registration roller from the control means, This transcription The paper is conveyed by the paper conveyance means without being secondary-transferred by the secondary transfer means, and the transfer paper is wound around the intermediate transfer drum, and a unit including the intermediate transfer drum is later pulled out to the outside, and the wound transfer paper is wound An image forming apparatus characterized in that the image is removed.