JPH0746255B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention develops an electrostatic latent image formed on a photoconductor with toner, and transfers the toner image onto a transfer paper or the like to obtain an image. The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus capable of scraping off residual toner on a photoconductor after a predetermined electrophotographic process with a blade.

(Prior Art) Image Forming Apparatus For example, an electrophotographic copying machine forms a predetermined electrostatic latent image on a photoconductor, develops the electrostatic latent image with toner, and then transfers the toner image onto a transfer paper. A copied image is obtained by transferring. The residual toner adhering to the surface of the photoconductor on which the toner image has been transferred onto the transfer paper is removed by the cleaning device, and the photoconductor is subjected to the next copying process.

A blade composed of an elastic body such as rubber is usually used as the cleaning device, and the residual toner on the surface of the photoconductor is scraped off by pressing the tip of the blade against the surface of the photoconductor.

Recently, in an electrophotographic copying machine, a toner image for image quality inspection is formed in an area other than an area on a photoconductor on which a copy image is to be formed, and the copy image quality can be improved based on the formed toner image. Has been done. For example, a document to be copied on the document table is placed in a non-exposure area, a document for image quality inspection is arranged, and when the document on the document table is exposed on the photoconductor, the document is exposed. Before, the image quality inspection document is exposed on the photoconductor to form an electrostatic latent image. An electrostatic latent image corresponding to the image of the original to be copied is formed behind the electrostatic latent image on the photoconductor. Then, for example, the density of the toner image obtained by developing the electrostatic latent image corresponding to the image quality inspection original with toner is measured, and the toner density control is performed so that the measured value becomes a predetermined target value. The device is controlled to obtain a copy image with a predetermined toner density. Further, the potential of an electrostatic latent image obtained by exposing a document for image quality inspection is measured to control the charge amount, the exposure amount, and the like.

The toner image for image quality inspection formed on the photoconductor is removed by the cleaning device without being transferred to the transfer paper. Behind the image quality inspection toner image on the photoconductor,
A toner image for copying is formed, and the cleaning device also removes toner remaining on the photoconductor after the toner image for copying is transferred to the transfer paper by the transfer device.

In this way, the image quality inspection toner image is removed by the cleaning device without being transferred to the transfer paper. In a cleaning device using a blade, the contact pressure of the blade with respect to the photoconductor is usually set so as to remove the toner remaining on the photoconductor after being transferred to the transfer paper.
Therefore, the high-density image quality inspection toner image that is not transferred onto the transfer paper cannot be completely scraped off by such a blade. In order to completely remove the toner image for image quality inspection, the blade pressure may be increased. However, if the blade pressure is increased, frictional deterioration of the photoconductor becomes severe and the life of the photoconductor is significantly reduced. Also, a strong force is required to drive the photoconductor.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and an object thereof is to reliably remove the toner image for image quality inspection and to prevent friction deterioration of the photoconductor. An object of the present invention is to provide an image forming apparatus capable of suppressing the life as much as possible and extending the life of the photoreceptor.

(Means for Solving Problems) An image forming apparatus of the present invention includes a unit for forming a toner image for transfer on a photoconductor, a unit for forming a toner image having an image right action on the photoconductor, and a photoconductor. An image forming apparatus having means for transferring a transfer toner image on a body to a transfer paper and means for removing unnecessary toner on a photoconductor, wherein the unnecessary toner removing means is a photosensitive member after transfer toner image transfer. A second state in which the toner remaining on the body is removed as unnecessary toner and a second state in which the toner image for image quality inspection on the photoconductor is removed as unnecessary toner without being transferred; The toner removing ability in the state is higher than the toner removing ability in the first state, whereby the above object is achieved.

(Examples) Examples of the present invention will be described below.

As shown in FIG. 1, the electrophotographic copying machine of the present invention has a photosensitive drum 10 in the substantially central portion of the machine body. The photosensitive drum
The upper part of 10 is the moving range of the optical system 11,
11 reciprocates within this moving range. A document placing table 12 is arranged above the moving area of the optical system 11, and an image of a copy document placed on the document placing table 12 when the optical system 11 moves forward is displayed.
The optical system 11 exposes the photosensitive drum 10 to light. Document holder 12
An image quality inspection document 13 is attached to the rear surface of the upper side plate of the fuselage adjacent to the exposure start side with the optical system
The reference numeral 11 first exposes the image quality inspection original document 13 when exposing the copy original document placed on the original document table 12.

The photoconductor drum 10 is rotatably arranged in a direction indicated by an arrow A, and a charging device 14 is provided at the photoconductor drum rotation direction upstream side of a position where the optical system 11 exposes the surface of the photoconductor drum 10. It is arranged so as to face the drum 10. The charging device 14
Charges the photosensitive drum 10 uniformly. A developing device 15 is disposed downstream of the exposure position on the surface of the photoconductor drum 10 by the optical system 11 in the rotation direction of the photoconductor drum. The developing device 15 exposes the photoconductor drum 10 by the exposure by the optical system 11. The electrostatic latent image formed on the surface is developed with toner.

A transfer device 16 and a separating device 17 are provided on the downstream side of the developing device 15 in the rotation direction of the photosensitive drum and below the photosensitive drum 10.
Are arranged side by side in the rotation direction of the photoconductor drum 10. The transfer device 16 transfers only the toner image corresponding to the copy original on the photoconductor drum 10 developed by the developing device 15 onto the transfer paper, and the separation device 17 exposes the transfer paper on which the toner image is transferred. Separated from body drum 10.

A cleaning device 20 is arranged at a position facing the developing device 15 with the photoconductor drum 10 interposed therebetween. The cleaning device 20 removes the toner attached to the photoconductor drum 10 by the developing device 15.

As shown in FIGS. 2 and 3, the cleaning device 20 has a blade 22 arranged in a housing 21 having an opening 21a. The opening 21a of the housing 21 is opened so as to face the drum 10, and the blade 22 is supported so as to come into contact with the surface of the drum 10 through the opening 21a.

The blade 22 has a flat plate shape made of an elastic material such as rubber, and is attached to the tip of the support plate 23 via a mounting member 24 so as to be parallel to the axis of the photosensitive drum 10. ing.

The support plate 23 is rotatably and substantially horizontally arranged on the support shaft 25 in the housing 21, and a blade is attached to an end of the support plate 23 close to the photosensitive drum 10 via a mounting member 24 having a T-shaped cross section. 22 upper ends are attached. Then, the side of the support plate 23 on which the blade 22 is disposed is rotated downward, so that the blade 22
One side edge of the lower end portion on the side of the photoconductor drum 10 can contact the surface of the photoconductor drum 10.

A weight 26 is attached to the side of the support plate 23 opposite to the side where the blades 22 are provided, and the support plate 23 is attached to the support plate 23 so that the blade 22 presses the photosensitive drum 10 at a predetermined pressure. Is urged.

An engagement protrusion 29 is provided on the weight 26 side of the support plate 23. One end of the wire 27 is locked to the engaging projection 29, and the other end of the wire 27 is a plunger that allows a solenoid 28 disposed on the upper surface of the housing 21 to move in the vertical direction. It is locked at the lower end of 28a. The solenoid 28
In the off state where no power is supplied, the plunger 28a
Although it is pulled by 6 and moves downward, when it is turned on, the plunger 28a is moved upward and the support plate 23 is weighed.
The blade 22 is rotated against the biasing force of 6 to separate the blade 22 from the photoconductor drum 10.

An opening 23a is formed at a substantially central portion of the support plate 23, and the support shaft 25 is inserted through the opening 23a. Then, at each end of the support shaft 25 located in the opening 23a,
The side portion of the pressing plate 31 is rotatably fitted. Press plate 31
Extends in a direction away from the photoconductor drum 10 and is located above the support plate 23.

An engaging projection 34 is provided on an end surface of the pressing plate 31 on the side where the weight 32 is provided, and one end of a wire 35 is locked to the engaging projection 34. The other end of the wire 35 is locked to a plunger 36a of a solenoid 36 arranged on the upper surface of the housing 21. When the solenoid 36 is off, its plunger 36
a is pulled downward by the weight 32. Then, the pressing plate 31
Rotates downward due to the weight of the weight 32, contacts the upper portion of the side edge of the opening 23a of the support plate 23, and presses the support plate 23 downward. As a result, the blade 22 is pressed against the surface of the photoconductor drum 10, and the contact pressure on the surface of the photoconductor drum 10 is increased. On the contrary, when the solenoid 36 is turned on, the plunger 36
The a pulls the weight 32 upward to rotate the pressing plate 32 upward so that the pressing plate 32 does not come into contact with the support plate 23.
The turning position of the pressing plate 31 when the solenoid 36 is turned on is such that the pressing plate 31 does not come into contact with the supporting plate 23 when the solenoid 28 is turned on.

Each solenoid 28 provided in the cleaning device 20 and
36 is controlled by the controller 40 as shown in FIG. The control section 40 is provided with a start button 41 for starting a copying operation and an output of a drum position detector 42 for detecting the rotational position of the photosensitive drum 10. The drum position detector 42 detects a predetermined position on the surface of the photoconductor drum 10 when the photoconductor drum 10 is rotated, by using an encoder mounted on the photoconductor drum 10, for example.

The operation of such an electrophotographic copying machine will be described based on the flowchart shown in FIG.

(1) First, the document to be copied is placed on the document table 12 and the start switch 41 is turned on. At this time, if the number of copies is 2 or more, the number of copies setting key (not shown) is operated to set the number of copies. When the start switch 41 is turned on, the solenoid 28 is turned off and the solenoid 36 is turned on. When the solenoid 28 is turned off, the support plate 23 of the cleaning device 20 is rotated by the weight 26, and the blade 22 is brought into contact with the surface of the photosensitive drum 10 at a predetermined pressure. In this case, when the solenoid 36 is turned on, the plunger 36a pulls the weight 32 upward, and the pressing plate 31 is not in contact with the support plate 23.

(2) In such a state, the main motor is driven. By driving the main motor, the optical system 11 starts moving, and the photosensitive drum 10 starts rotating. Drum position detector
The counter 42 starts counting the pulses emitted from the encoder as the photosensitive drum 10 rotates.
The optical system 11 first exposes the image quality inspection document 13 on the surface of the photoconductor drum 10 to form an electrostatic latent image thereof, and then copies the document on the document table 12 onto the image quality inspection document. The surface of the photosensitive drum 10 adjacent to the electrostatic latent image is exposed to form an electrostatic latent image. These electrostatic latent images are sequentially subjected to toner development by the developing device 15, and the toner image for image quality inspection is measured for its toner concentration by, for example, a toner concentration detector (not shown). The toner image for image quality inspection is sent to the position facing the cleaning device 20 without being transferred from the surface of the photosensitive drum 10 to the transfer paper by the transfer device 16.

(3) When the pulse count reaches a predetermined number, that is, the drum rotation position detector 42 causes the toner image of the image quality inspection document on the surface of the photoconductor drum 10 to be cleaned by the cleaning device 20.
When detecting that it has reached a predetermined position in the vicinity of, the control unit 40 turns off the solenoid 36. This allows the pressing plate
The weight 31 is rotated downward by a weight 32 to come into contact with the support plate 23, and the support plate 23 is also pressed by the weight 32. Due to this pressing, the blade 22 contacting the surface of the photoconductor drum 10
The surface of the photosensitive drum 10 is pressed more strongly. At this time,
A timer in the control unit 40 is operated. While the blade 22 strongly presses the surface of the photosensitive drum 10,
Is rotated. Along with the rotation, the toner image for image quality inspection reaches a position facing the cleaning device 20, and is scraped off from the photoconductor drum 10 by the blade 22 that strongly abuts the surface of the photoconductor drum 10.

(4) When the timer measures the time required for the toner image for image quality inspection on the surface of the photosensitive drum 10 to pass through the contact position of the blade 22, the solenoid 36 is turned on, and the plunger 36a pulls the weight 32, The pressing plate 31 is separated from the support plate 23. As a result, the blade 22 moves the weight 32 of the pressing plate 31.
The pressing force due to is released, and the weight 26 comes into contact with the surface of the photosensitive drum 10 only by its own weight. On the other hand, the photosensitive drum 10
The copying toner image formed on the surface is transferred onto the transfer paper by the transfer device 16, and the transfer paper is separated from the photosensitive drum 10 by the separating device 17 and conveyed. Then, the surface of the photoconductor drum 10 after the toner image is transferred is fed to a position facing the cleaning device 20, and as described above, the blade 22 abuts on the surface of the photoconductor drum 10 only by the weight of the weight 26. When the toner remains on the surface, the toner is scraped off.

(5) When the set number of copies is 1, the following (7) is performed.

(6) When the set number of copies is 2 or more, the above (2) to (4) are repeated to perform the set number of copies. When copying of the set number of sheets is completed, the process proceeds to the next (7).

(7) When the surface of the photoconductor drum 10 on which the toner image for copying is formed passes the blade 22 contact position, the drive of the main motor is stopped, the solenoid 28 is turned on, and the plunger 28a moves the weight 26. The blade 22 is pulled so that the blade 22 is separated from the surface of the photoconductor.

(8) This completes the copying process and puts the electrophotographic copying machine in a standby state.

Although the above description has been given of the example in which the image quality inspection toner image is formed for each copying operation even when the number of copies is two or more, the control mode of the image forming apparatus of the present invention is not limited to this. For example, even in such continuous copying, when the image is formed and the toner density control is performed only during the first copying operation, the above (2) to (7) are performed only during the first copying operation. .

(Effects of the Invention) In the electrophotographic copying machine of the present invention, when the toner image for image quality inspection formed on the photoconductor is scraped off, the blade pressure applied to the surface of the photoconductor is increased to transfer the transfer paper. When the toner remaining on the surface of the photoconductor after being transferred to the surface of the photoconductor is scraped off, since the blade pressure applied to the surface of the photoconductor is low, the toner image for image quality inspection is reliably removed from the photoconductor and There is no risk of adversely affecting the. Since the blade pressure can be increased only when the toner image for image quality inspection is scraped off, friction deterioration of the photoconductor can be suppressed, and as a result, the life of the photoconductor can be increased and the sliding contact sound volume can be increased. Absent.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an electrophotographic copying machine of the present invention,
FIG. 2 is a sectional view of the main part, and FIG. 3 is III-III of FIG.
FIG. 4 is a block diagram of the control circuit, and FIG. 5 is a flow chart for explaining the operation. 10 …… Photosensitive drum, 11 …… Optical system, 13 …… Image quality inspection document, 20 …… Cleaning device, 22 …… Blade, 23 …… Support plate, 26, 32 …… Weight, 28, 36 …… Solenoid, 31 ... Pressing plate.

Claims (1)

[Claims] 1. A means for forming a transfer toner image on a photoconductor, a means for forming a toner image for image inspection on the photoconductor, and a transfer toner image on the photoconductor onto a transfer paper. An image forming apparatus having means and means for removing unnecessary toner on the photoconductor, wherein the means for removing unnecessary toner removes toner remaining on the photoreceptor after transfer toner image transfer as unnecessary toner. 1
A state and a second state when the image quality inspection toner image on the photoconductor is removed as unnecessary toner without being transferred,
An image forming apparatus characterized in that the toner removing ability in the second state is higher than the toner removing ability in the first state.