JP2863536B2 - Image forming apparatus having belt-shaped image carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus such as a copying machine and a laser printer,
More specifically, the present invention relates to an image forming unit that supports a belt-shaped photoreceptor (photoreceptor belt) and that can be replaced when the life of the belt expires.

(Prior art)

Conventionally, a belt-shaped photoreceptor having a detection marker is supported so as to be able to circulate, a detection window for the detection marker is provided, and an image formation start position is detected by detecting the detection marker by a detection sensor in an image forming apparatus main body. A photoreceptor unit of an image forming apparatus that determines the image quality is known. In such a conventional photoreceptor unit, a new photoreceptor belt at the time of product shipment is such that the seam of the belt is immediately below a position where a cleaning blade of a cleaning unit of an image forming apparatus, for example, a laser printer abuts on the photoreceptor belt. And this position is the home position. When an unused photoreceptor unit having the photoreceptor belt arranged in this way is set in the image forming apparatus and the first image is formed, the frictional force between the cleaning blade and the photoreceptor belt causes no toner at all. When the image is transferred from the portion where the toner is not attached to the portion where the toner is attached, the photoconductor belt suddenly changes, causing a slip on the photoreceptor belt. Therefore, there is a problem that a black band extending in the lateral direction is generated on the transferred image.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide an image forming apparatus provided with a belt-shaped photosensitive member that does not adversely affect image quality.

[Means for solving the problem]

According to the present invention, the above problem is detected by a detection sensor via a detection window for a detection marker, wherein a belt-shaped photoreceptor having a detection marker is supported so as to be able to circulate and is arranged to abut on a cleaning blade. In an image forming apparatus that determines an image forming start position by detecting a marker, a new belt-shaped photoreceptor attached to the image forming apparatus is assembled at a position after the detection marker has passed the detection window in the moving direction. The first image formation after a new belt-shaped photoreceptor is mounted on the image forming apparatus, the photoreceptor idles for approximately one rotation of the belt-shaped photoreceptor, and the toner is transferred from the developing device. The problem was solved by being controlled to start after being supplied.

[Action]

When an unused, that is, a new photoreceptor belt is attached to the image forming unit, the first image forming operation is performed only after the belt is rotated substantially once and toner is replenished. The toner adheres to the cleaning blade in contact with the belt, and abrupt changes in the frictional force between the belt and the blade are reliably prevented before the start of image formation, regardless of the position of the belt seam.

〔Example〕

 The details of the present invention will be described based on an embodiment shown in the drawings.

In FIG. 1, an image forming apparatus utilizing the present invention, for example, a laser printer 1 includes a photosensitive unit 3 detachably mounted on an upper unit 2, a paper feed cassette 5 mounted on a lower unit 4, and a fixing unit. A unit 6 and a paper discharge tray 7 are provided.

The photoconductor unit 3 is formed, for example, as shown in FIG. 2, and is considered so that it can be easily attached to and detached from the upper unit 2. In the casing 8 of the photoconductor unit 3, a detection window 10 for detecting a detection marker provided on the belt-shaped photoconductor (photoconductor belt) 9 is formed, and a cleaning unit 11 is provided.

In the laser printer 1, as shown in FIG. 3, a photoreceptor belt (for example, an OPC belt) 9 is
, Exposed by the laser exposure device 13, and developed by the developing roller 14.

The developed toner image on the photoreceptor belt 9 is sent out from a sheet feeding cassette 15 by a sheet feeding roller 16 or is sent out from a sheet feeding tray by a pickup roller 17 and a feed roller 18, and passes through a grip roller 19 and an intermediate roller 20. The sheet is transferred by a transfer charger 22 onto a sheet which is registered by a registration roller 21 and fed in synchronization with the photoreceptor belt 9.

The transferred paper is fixed by a transport roller 23 to a fixing roller device.
The sheet is conveyed to 24, fixed and discharged.

After the transfer, the photoreceptor belt 9 is cleaned by the cleaning blade 25 of the cleaning unit 11, is discharged by the discharge lamp 26, and the image forming process from charging is repeated again.

Photoconductor unit (OPC belt magazine) shown in Fig. 2
As shown in FIGS. 4 and 5, a belt-shaped photoreceptor (OPC belt) 9 is incorporated in 3 so as to be wound around a driving roller 27, a driven roller 28, and a tension roller 29.

The belt-shaped photoreceptor 9 has a joint 30. The image forming start position is set so that the exposure device 13 performs exposure after the joint 30 passes during image formation.

The belt-shaped photoconductor 9 is provided with a detection marker 31 for determining an image formation start position. A detection sensor is provided in the image forming apparatus 1, for example, in the upper unit 2 to detect the detection marker 31, and a detection window 10 is provided in the casing 8 in order to detect the detection marker 31 by the detection sensor.
Is formed.

When the detection marker 31 of the belt-shaped photoconductor 9 passes through the detection window 10, the detection sensor detects the detection marker 31, and based on the detection signal, the image forming start timing is set in synchronization with the detection of the detection marker 31. For example, if it is determined that image formation is to be started from the time of detection of the detection marker 31 by the detection sensor, the seam 30 starts charging by passing through the charging charger at the time of detection, and after the seam 30 passes, the exposure device 13
Exposure starts. In such an example, at the time of shipment of an unused photoreceptor unit to which a new photoreceptor belt 9 is attached, the detection marker 31 of the photoreceptor belt 9 is at a position immediately after passing through the detection window 10 as shown in FIG. like,
The assembly state of the photoreceptor belt 9 is adjusted.

In this way, when an unused photoreceptor unit is mounted on the upper unit 2 and a print start command is received for the first time, the photoreceptor belt 9 starts to circulate, the developing roller 14 also rotates, and the photoreceptor belt 9 Means that toner adheres.

The photoreceptor belt 9 circulates and the toner adhering start portion reaches a new cleaning blade 25 without toner adhering,
The toner adhered on the photoreceptor belt 9 is cleaned.

Conventionally, the cleaning blade 25
At this point, a horizontal black band was generated due to the slip at this point because the transfer had already started. However, in the present invention, not only the transfer but also the image formation has not been started yet, so that the black band image is not formed by the horizontal black band.

The photoconductor belt 9 circulates almost once and the detection marker 31
The operation for forming the first image is started only when or crosses the detection window 10.

At the start of the first image formation, since the toner has already adhered to the cleaning blade 25, the frictional force of the photosensitive belt 9 does not suddenly change.

When the photoconductor unit 3 is shipped, in the state shown in FIG. 5, the tension roller 29 and the cleaning blade 25 are locked so that no tension is applied.
Even if the photoreceptor belt 9 is stored unused for a long time, the photoreceptor belt 9 does not bend.

If the operation is started for the first time after shipment, the image formation is started at the time when the photoreceptor belt rotates substantially once, thereby eliminating the influence of the rapid change in the frictional force of the photoreceptor belt as described above. At this time, the rotation is not necessarily limited to exactly one rotation, and may be any length that is close to one rotation and runs idle so as to eliminate a sudden change in frictional force of the photosensitive belt. For this reason, the position of the detection marker is not necessarily limited to immediately after passing through the detection window.

〔effect〕

According to the present invention, the photoreceptor belt is rotated substantially once before the first image formation with the new image forming unit attached, and toner is replenished on the belt. Since toner adheres and image formation is started after that,
When the transfer of the toner image is performed, the frictional force between the cleaning blade and the photosensitive belt does not change suddenly, and image defects such as a horizontal black band do not occur.

[Brief description of the drawings]

1 is an overall perspective view of an image forming apparatus used in the present invention, FIG. 2 is a perspective view of a photoreceptor unit, FIG. 3 is a schematic diagram illustrating an image forming process, and FIG. FIG. 5 is an explanatory perspective view of a photoreceptor belt of the body unit, and FIG. DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 3 ... Photoconductor unit 9 ... Photoconductor belt, 10 ... Detection window 31 ... Detection marker

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-55-124174 (JP, A) JP-A-58-142379 (JP, A) JP-A-62-15566 (JP, A) JP-A-59-124 111167 (JP, A) JP-A-62-124570 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/10-21/12 G03G 21/00 370-540 G03G 21 /14

Claims (1)

(57) [Claims] A belt-like photoreceptor having a detection marker is supported so as to be capable of circulating and is arranged so as to abut a cleaning blade. The detection marker is detected by a detection sensor through a detection window for the detection marker. In the image forming apparatus which determines the image forming start position by performing the above operation, the new belt-shaped photoreceptor attached to the image forming apparatus is mounted such that the detection marker is assembled at a position after passing the detection window in the moving direction. In the first image formation after a new belt-shaped photoconductor is mounted on the image forming apparatus, toner is supplied from the developing device by spinning the photoconductor for almost one rotation of the belt-shaped photoconductor. An image forming apparatus controlled to start later.