JPH06324533A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the developer stuck on the surface of a photoreceptor drum from being stuck to a transfer roller, fouling the recording paper, and generating irregularities of density on an image when transfer is interrupted by jamming or the like during the transfer of the image. CONSTITUTION:An image forming device is provided with a photoreceptor drum 11 carrying a developer image provided on an upper structural member 1, a transfer roller 22 provided on a lower structural member 2 and kept in rolling contact with the photoreceptor drum 11 via the recording paper P so that they can be contacted or removed each other by the vertical rotation of the upper structural member 1, a sensor SE detecting the separation between the photoreceptor drum 11 and the transfer roller 22, and a controller 10 rotatively driving the photoreceptor drum 11 to the angle theta or above between the position A facing a developing unit 16 and the position B facing the transfer roller 22 when the sensor SE detects the separation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention passes a recording sheet between a photosensitive drum, which is an image carrier, and a transfer roller to which a bias voltage is applied to transfer the developer image on the photosensitive drum onto the surface of the recording sheet. The present invention relates to a so-called contact transfer type image forming apparatus.

[0002]

2. Description of the Related Art A contact transfer type image forming apparatus does not require a high-voltage power source as compared with a type in which transfer is performed by using a corona discharger, has a low running cost, and is accompanied by ozone and nitrogen generated by high-voltage discharge. There are advantages such as no generation of oxides, less deterioration of the photosensitive drum due to these, and no trouble due to dirt on the corona discharger.

On the other hand, however, since the transfer roller and the photosensitive drum are in rolling contact with each other, the jammed recording paper is removed when jamming occurs due to jamming of the recording paper during recording and the transfer is interrupted. Then, when copying is restarted, the developer already attached to the surface of the photosensitive drum adheres to the surface of the transfer roller, and when the recording paper passes, the developer adheres to the back surface of the recording paper and stains the back surface of the recording paper. In addition, there is a problem that the developer attached to the transfer roll becomes an obstacle, and the transfer of the developer from the photosensitive drum to the surface of the recording sheet is uneven, which may cause unevenness of light and shade in the image.

As a countermeasure against this, conventionally, the developer attached to the transfer roller is removed by using a means for scraping the attached toner by touching the transfer roller with a blade, a brush, a felt or the like, or a polarity control charger. A means for reverse transfer onto the surface of the photosensitive drum has been proposed.

[0005]

However, in the former method, the surface of the transfer roller is not always smooth and there are many fine irregularities. Therefore, the developer adhering to the concave portions may scrape off the surface. In the latter method, there is a problem that the developer having a van der Waals force against the generated electric charge cannot be reverse-transferred to the photosensitive drum side and remains on the transfer roller surface. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus capable of reducing the adhesion of toner to the surface of a transfer member.

[0006]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention comprises an image carrier for carrying a developer image and a developer provided around the image carrier, and a developer for the image carrier. And another component having a transfer member that presses the recording paper to separate the recording paper in order to transfer the image, and by moving one of the components with respect to the other, the image carrier and the transfer member. In an image forming apparatus capable of contacting and separating from each other, a sensor that detects that the image carrier and the transfer member are separated from each other, and, when the sensor detects separation, at least the image carrier is the developing device. And a drive control unit for rotating and driving the transfer member at an angle equal to or greater than an angle between the transfer member and the transfer member.

[0007]

According to the present invention, this prevents the area of the image carrier on which the developer remains adhering to the transfer member without being transferred to the transfer sheet, thereby preventing the transfer member surface from being soiled. Can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A case in which the present invention is applied to a copying machine will be specifically described below with reference to the drawings showing an embodiment. FIG. 1 is a schematic side sectional view of an image forming apparatus according to the present invention, and FIG. 2 is also an operation explanatory view thereof, in which 1 is an upper constituent member that is a movable side and 2 is a lower constituent member that is a stationary side. Is shown.
The upper constituent member 1 and the lower constituent member 2 are arranged so as to face each other in an upper direction and a lower direction, and the opposite one end side edge portions thereof are pivotally supported by a shaft 3 so that the upper constituent member 1 is as shown in FIG. It can be rotated between a closed state where they are joined to each other and an open state where the upper component 1 is moved upward as shown in FIG. Reference numeral 4 denotes a locking tool provided at the other end side edge portions of the upper constituent member 1 and the lower constituent member 2 facing each other.

In the upper component 1, a photosensitive drum 11, which is an image bearing member, is attached to a frame (not shown), a cleaning device 12, a discharging lamp 13, a charging roller 14 are provided along the periphery thereof.
The exposure lamp 15 and the developing device 16 are further provided with a paper feed roller 17, a registration roller 18, a heat roller 19, a driving motor M, and a control unit 10 thereof along the surface facing the lower component 2. The outer periphery is covered with a case except for the side facing the lower component 2. The control unit 10 controls the motor M and the above-mentioned members. On the other hand, in the lower component 2, the paper feed tray T ₁ is also provided on one end of the frame.
The discharge tray T ₂ is grounded on the other end side, and a registration roller 21, a transfer roller 22 and a fixing roller 23 are installed along the surface facing the upper component 1.

When the upper component 1 and the lower component 2 are opposed to each other as shown in FIG. 1, the paper feed roller 17 is in pressure contact with the surface of the transfer paper P in the paper feed tray T ₁ and the registration roller 18 is provided. Is a registration roller 21, the photosensitive drum 11 is a transfer roller 22, the heat roller 19 is a fixing roller 23, and the registration rollers 18 and 21 are a photosensitive drum 11.
Gears (not shown) provided on respective shafts of the transfer roller 22, the heat roller 19, and the fixing roller 23 when they face each other.
Mesh with each other, and the power of the motor M is transmitted to each part of the lower component 2.

In the image forming apparatus according to the present invention, an open / close detection sensor SE composed of a photo sensor or the like is provided at a position near the other end of the upper component 1, and a lower component 2 facing the open / close sensor SE. The projection 24 is provided on the. Figure 1
When it is in the closed state as shown in FIG. 2, the projection 24 is engaged in the opening / closing detection sensor SE to block the light from the light source and the light receiving element, and as shown in FIG. When the protrusion 24 is rotated and comes out of the open / close detection sensor SE, the light from the light source is captured by the light receiving element, and it is detected that the upper component 1 is in the open state.

When the open / close detection sensor SE detects the open / closed state, the control unit 10 drives the motor to move the photosensitive drum 11 to the developing unit 16.
Is rotated by an angle .theta. Or more, which is sandwiched between a portion A opposed to the transfer roller 22 and a portion B opposed to the transfer roller 22.
As a result, the area where a large amount of developer is attached is moved to a position where it does not face the transfer roller 22, and is collected by the cleaning device 12 when copying is resumed.

Next, the operation of such a device of the present invention will be described. The photosensitive drum 11 is rotationally driven in the direction of the arrow by the motor M. First, the front surface of the surface is uniformly charged at a position facing the charging device 14, and is exposed at a position facing the exposing device 15 to form an electrostatic latent image. It is formed. Next, a developer is made to adhere to the surface at a position facing the developing device 16 and visualized,
The developer image is transferred onto the recording paper P at a position facing the transfer roller 22. The recording paper P is accommodated in the paper feed tray T ₁ , taken out one by one by the paper feed roller 7, and fed by the registration rollers 18 and 21 at a predetermined timing.

After the transfer is completed, the photoconductor drum 11 collects the residual developer by the cleaning device 12, and then the charge is removed at a position facing the charge removal lamp 13, and the above process is repeated again. On the other hand, the recording paper P on which the developer image is transferred is fixed with the developer in the process of passing between the heat roller 19 and the fixing roller 23, and is discharged onto the paper discharge tray T ₂ .

Next, the operation at the time of occurrence of jamming such as paper jam will be described with reference to the flowchart shown in FIG.
When the jamming occurs, the motor M is stopped by a sensor (not shown), and the copying operation is stopped (step S1). The worker uses the locking device 4 to remove the jammed paper.
And the upper constituent member 1 is rotated upward around the shaft 3 to change the state shown in FIG. 1 to the state shown in FIG. As a result, the opening / closing detection sensor SE detects the opening of the upper component when the protrusion 24 comes out of the opening / closing detection sensor SE. Therefore, in the determination as to whether the open / close detection sensor SE has detected the open state in step S2, the control unit 10 rotates the motor M by θ / ω (ω: angular velocity rad / sec) or more and stops because it is in the open state. (Step S3).

When the cause of the jamming has been eliminated, the upper component member is rotated about the axis 3 and returned to the position shown in FIG. 1, and the opening / closing detection sensor SE is in a state of detecting closure. Therefore, in the judgment as to whether or not the opening / closing detection sensor SE has detected the closing in step S4, since the closing is being detected, the routine returns.

By rotating the photosensitive drum 11 for θ / ω seconds or more, the area of the photosensitive drum 11 on which the developer is attached is rotated by θ, and this area is positioned so as not to face the transfer roller 22. When the upper component 1 is returned to the closed position, the developer does not adhere to the photoreceptor drum 11 or the developer does not adhere to the photoreceptor drum 11 very little.
Therefore, the peripheral surface of the roller is brought into rolling contact with the surface of the transfer roller 22, and the transfer roller 22 can be prevented from being contaminated with the developer.

While the photosensitive drum 11 is rotated by θ or more, the developer adheres to the surface of the photosensitive drum 1 from the developing device 16, but the amount of the developer adhered at this time is small and the transfer roller 22. Contamination of will be kept to a minimum. Further, in the above-described embodiment, the configuration is shown in which the motor M is electrically driven by θ / ω seconds by the control unit 10 during the jamming. Of course, the body drum 11 may be rotated by θ.

Further, in the above-described embodiment, the rotation angle θ of the photosensitive drum 11 at the time of jamming is the contact point A, B with the developing device 16 and the transfer roller 22 as a reversal developing type copying machine.
The angle is equal to or greater than the angle between, but is not particularly limited to this,
For example, the charging roller 14,
The angle may be equal to or larger than the angle between the contact points A and C with the transfer roller 22.

[0020]

As described above, in the image forming apparatus according to the present invention, the image carrier is rotated by a predetermined angle when the image carrier and the transfer member are separated from each other during jamming, maintenance and inspection. As a result, the portion of the image carrier on which the developer is not attached can be opposed to the portion that faces the transfer member, and the developer adheres to the transfer member and stains the back surface of the recording paper, and It is possible to surely prevent the unevenness of light and shade from occurring, which is an excellent effect.

[Simple title of drawing]

FIG. 1 is a schematic side sectional view of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram of the same operation.

FIG. 3 is a flowchart showing a processing order.

[Explanation of symbols]

 1 Upper component 2 Lower component 3 Shaft 4 Locking tool 11 Photoconductor drum 16 Developer SE Open / close detection sensor

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[Procedure amendment]

[Submission date] June 3, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention comprises an image carrier for carrying a developer image and a developer provided around the image carrier, and a developer for the image carrier. And another component having a transfer member that presses the recording paper to separate the recording paper in order to transfer the image, and by moving one of the components with respect to the other, the image carrier and the transfer member. In the image forming apparatus capable of contacting and separating from each other, when the image carrier and the transfer member are separated from each other , the image carrier is at least between a part facing the developing device and a part facing the transfer member. Driving hands that rotate over an angle of
Characterized in that it comprises a stage.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Next, the operation when jamming such as paper jam occurs will be described with reference to the flow chart shown in FIG.
When jamming occurs, the motor M is stopped by a sensor (not shown), and the copying operation is stopped (step S1). The worker uses the locking device 4 to remove the jammed paper.
And the upper constituent member 1 is rotated upward around the shaft 3 to change the state shown in FIG. 1 to the state shown in FIG. As a result, the opening / closing detection sensor SE detects the opening of the upper component when the protrusion 24 comes out of the opening / closing detection sensor SE. Therefore, in the determination as to whether the open / close detection sensor SE detects the open state in step S2, the control unit 10 rotates the motor M by θ / ω (ω: angular velocity rad / sec) or more and stops because it is in the open state. (Step S3).

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

When the cause of jamming has been eliminated, the upper component member is rotated about the axis 3 and returned to the position shown in FIG. 1, whereupon the open / close detection sensor SE detects the closure. Therefore, in the judgment as to whether or not the opening / closing detection sensor SE has detected the closing in step S4, since the closing is being detected, the routine returns.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

While the photosensitive drum 11 is rotated by θ or more, the developer adheres to the surface of the photosensitive drum 1 from the developing device 16, but the amount of the developer adhered at this time is small and the transfer roller 22. Contamination of will be kept to a minimum. Further, in the above-described embodiment, the configuration is shown in which the motor M is electrically driven by the control unit 10 for θ / ω seconds during jamming. Of course, the body drum 11 may be rotated by θ.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Further, in the above-described embodiment, the rotation angle θ of the photosensitive drum 11 at the time of jamming or the like is the contact points A and B with the developing device 16 and the transfer roller 22 as a reversal developing type copying machine.
The angle is equal to or greater than the angle between, but is not particularly limited to this,
For example, the charging roller 14,
The angle may be equal to or larger than the angle between the contact points A and C with the transfer roller 22.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

[0020]

As described above, in the image forming apparatus according to the present invention, the image carrier is rotated by a predetermined angle when the image carrier and the transfer member are separated from each other during jamming , maintenance and inspection. As a result, the portion of the image carrier on which the developer is not attached can be opposed to the portion that faces the transfer member, and the developer adheres to the transfer member and stains the back surface of the recording paper, and It is possible to surely prevent the unevenness of light and shade from occurring, which is an excellent effect.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram of the same operation.

FIG. 3 is a flowchart showing a processing order.

[Explanation of reference numerals] 1 upper constituent member 2 lower constituent member 3 shaft 4 locking tool 11 photoconductor drum 16 developing device SE open / close detection sensor

Claims (1)

[Claims] 1. A structure comprising an image carrier for carrying a developer image and a developing device arranged around the image carrier, and a recording sheet for press-contacting the developer image on the image carrier to transfer the developer image. An image forming apparatus capable of bringing the image carrier and the transfer member into and out of contact with each other by moving one of the structures with respect to the other. A sensor that detects that the image carrier and the transfer member are separated from each other, and a sensor that detects the separation of the image carrier from the image carrier at least a portion facing the developing device and a portion facing the transfer member. An image forming apparatus, comprising: a drive control unit that rotates and drives by an angle greater than or equal to the angle.