JP2001142369A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the back surface staining of transfer material by excellently cleaning a transfer carrying belt in the case of transferring a patch image to the transfer carrying belt carrying the transfer material. SOLUTION: The tandem system color image forming device is provided with a blade type cleaning device 17 for the endlessly turning transfer carrying belt 7 carrying and feeding the transfer material. By turning the belt 7 until density detected by a density detector 20 detecting the density of the patch image formed on the belt 7 becomes the specified density, the patch image is removed by the device 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art FIG. 6 is a schematic diagram showing the structure of a conventional image forming apparatus such as a color copying machine or a color printer.

The color image forming apparatus shown in FIG. 6 is a tandem type color image forming apparatus in which image forming stations for forming toner images of respective colors by an electrophotographic process are arranged in a line. A paper passing path 4 is provided between a paper supply unit 2 formed of a cassette or the like and a paper discharge unit 3 formed of a paper discharge tray or the like. A transfer conveyance belt 7 included in the paper passage path 4 conveys a recording paper and transfers a toner visible image on a photosensitive drum 9 of each color forming station as an image carrier on which a latent image is formed by exposure. I do. The latent image formed on the photosensitive drum 9 is
The image is developed by the toner of the developing device and visualized, and is transferred to a transfer material carried on the transfer / conveying belt 7 by a transfer device when a normal image is formed.

The transfer / conveying belt 7 is stretched by a belt driving roller 5 to which a driving force is applied by a driving source (not shown) and a rotatable belt driven roller 6, and is rotated by the application of the driving force. Image forming stations 8Y, 8M, 8C, 8K by four electrophotographic processes for yellow, magenta, cyan, and black are provided on the transfer / conveying belt 7.
Are arranged in this order.

The image forming station 8 includes a photosensitive drum 9 in contact with the transfer / conveyance belt 7, and a charger 10, an exposure device 11, a developing device 12, and a transfer device 1 disposed around the photosensitive drum 9.
3 and a photoreceptor cleaner 14 are sequentially arranged and formed.

An optical density sensor 20 and a cleaning device 17 for cleaning unnecessary toner on the transfer and conveyance belt 7 are provided on the transfer and conveyance belt 7 downstream of the image forming station. Then, the fixing device 15 is disposed at the most downstream portion of the paper passing transport path 4.

According to another embodiment, the transfer / conveying belt 7
The unnecessary toner on the transfer conveyance belt is returned to the photosensitive drum in the process cartridge in place of the cleaning device 17 of FIG.
And the dedicated cleaning device 17 can be omitted.

[0008] With such a structure,
The uppermost recording paper 1 is sent out to the paper path, and is conveyed by the transfer conveyance belt 7. In this process, the image formed by the electrophotographic process of charging, exposure and development by the electrophotographic process unit 8 of each color is sequentially transferred onto the recording paper 1 by the transfer unit 13 arranged in the transfer and conveyance belt 7. A multi-transfer forms a color image, which is heated and pressed by the fixing device 15 and firmly adheres to the recording paper 1, thereby completing the image formation.

In the above-described color copying machines and color printers, stable color reproducibility is always required, so that a toner image for density detection (hereinafter referred to as a patch image) having various density patterns is transferred onto a transfer belt. The density of the patch image is measured by the optical density sensor 20, and the control unit 18 controls the process conditions of the image forming station for each color based on the measurement result.

[0010]

In such an image forming apparatus, in order to form a patch image as a control image on the transfer / conveying belt 7, the above-described cleaning means for cleaning the patch image is used. It is necessary to provide.

However, the transfer conveyance belt 7 due to a change over time
Since the cleaning property deteriorates due to the deterioration of the surface property of the cleaning blade and the abrasion of the edge of the cleaning blade, cleaning failure due to aging may occur under the same cleaning conditions as in the initial stage. Of the transfer material was sometimes stained with toner.

An object of the invention according to the present application is to solve the above-mentioned problem of cleaning the transfer / conveying belt, perform the cleaning of the transfer / conveying belt satisfactorily over a long period of time, and prevent back contamination of the transfer material. An image forming apparatus is provided.

[0013]

A first configuration for realizing the object of the invention according to the present invention is obtained by developing a latent image formed on a latent image carrier by an image exposure unit by a development unit. The toner image is transferred to the transfer material carried on the transfer material carrier via the transfer means, and the surface of the transfer material carrier is cleaned by the cleaning means, and the control toner image formed on the latent image carrier is removed. In an image forming apparatus in which the image is transferred onto the transfer material carrier and read by a density detection sensor, cleaning control by the cleaning unit is performed according to a detection output of the density detection sensor. .

A second configuration for realizing the object of the invention according to the present application is to form a multi-color image by obtaining a toner image by developing a latent image formed on a latent image carrier by an image exposure unit by a development unit. A station, an endlessly rotating transfer material carrier that conveys a transfer material to be carried to a transfer portion of the image forming station, and a transfer unit that transfers toner images of the image forming stations of the respective colors to the transfer material at transfer portions. A color image was formed by sequentially superimposing toner images of each color on the transfer material, and the surface of the transfer material carrier was cleaned by a cleaning unit, and formed on the latent image carrier of each station. In an image forming apparatus in which a control toner image is transferred to the transfer material carrier and is read by a density detection sensor, the density detection sensor Out in accordance with the output, and performs cleaning control by the cleaning means.

A third structure for realizing the object of the invention according to the present application is the first or second structure, wherein the cleaning means is a cleaning device using an electrostatic attraction force. .

A fourth structure for realizing the object of the present invention according to the present invention is the first or second structure, wherein the cleaning means is a cleaning device using a blade.

A fifth configuration for realizing the object of the invention according to the present application is the first or second configuration, wherein the cleaning means is a cleaning device using a fur brush and a bias applied thereto. And

A sixth configuration for realizing the object of the invention according to the present application is the first or second configuration, wherein the cleaning unit rotates the transfer material carrier until a predetermined density is reached. The cleaning control is performed.

A seventh configuration for realizing the object of the invention according to the present application is the third configuration described above, wherein the cleaning means comprises:
The cleaning control is performed by changing the electrostatic attraction force.

An eighth structure for realizing the object of the present invention according to the present application is the fourth structure, wherein the cleaning means comprises:
The cleaning control is performed by adjusting a contact pressure at which the blade comes into contact with the transfer material carrier.

A ninth configuration for realizing the object of the present invention according to the present application is the fifth configuration, wherein the cleaning device comprises:
The cleaning control is performed by adjusting the contact pressure at which the fur brush contacts the transfer material carrier and changing the applied bias.

The tenth embodiment for realizing the object of the invention according to the present application is as follows.
Wherein the cleaning means is a cleaning device combining a method using electrostatic attraction, a method using a cleaning blade, and a method using a fur brush and its applied bias. It is characterized by something.

An eleventh embodiment for realizing the object of the invention according to the present application
Is configured to transfer a toner image obtained by developing the latent image formed on the latent image carrier by the image exposure unit by the developing unit to the transfer material carried on the transfer material carrier via the transfer unit. Further, the control toner image formed on the latent image carrier is transferred to the transfer material carrier and read by a density detection sensor, and the toner on the transfer material carrier is transferred to the latent image carrier. In the image forming apparatus, which is re-transferred to the body and is cleaned by the cleaning device for the latent image carrier, the re-transfer operation is executed until the detection output of the density detection sensor reaches a predetermined value to perform cleaning. It is characterized by.

A twelfth embodiment for realizing the object of the invention according to the present application.
The image forming station includes a plurality of image forming stations for obtaining a toner image by developing the latent image formed on the latent image carrier by the image exposing means by the developing means, and a transfer material for transferring the transfer material to the image forming station. And a transfer means for transferring the toner image of the image forming station of each color to the transfer material at a transfer portion, and sequentially superimposes the toner images of each color on the transfer material. In this way, a color image is formed, and the control toner image formed on the latent image carrier of each station is transferred to the transfer material carrier, and is read by a density detection sensor. Image formation in which the toner on the material carrier is retransferred to all of the latent image carriers or any of the latent image carriers, and is cleaned by the latent image carrier cleaning means. In location, the detection output of the density detection sensor and performs the cleaning by performing the re-transfer operation to a predetermined value.

The difference between the configuration of the present invention described above and the conventional configuration shown in FIG. 6 lies in the following control.

That is, in a tandem type color image forming apparatus as shown in FIG. 6, a patch image for image density detection as a control patch image formed on a photosensitive drum 9 is directly transferred onto a transfer / conveying belt 7. Then, by detecting this toner image by the optical density sensor 20, image correction control such as density correction control and halftone correction control is performed.

Since the density detecting sensor 20 detects the amount of toner on the transfer / conveying belt 7, it can also detect unnecessary toner on the transfer / conveying belt 7. Optimum cleaning conditions can be adapted.

As described above, by adapting the optimum cleaning conditions according to the amount of the unnecessary toner on the transfer / conveying belt 7, a system free from cleaning failure for a long period of time can be realized.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image forming apparatus according to the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment.

The image forming apparatus of the present embodiment is configured substantially in the same manner as the conventional image forming apparatus shown in FIG. 6, and is the same as the conventional example shown in FIG. Shows only the main part, and the characteristic cleaning process will be described below.

In the image forming apparatus shown in FIG. 1, a toner image (hereinafter, referred to as a patch image) 21 used for image density correction control performed prior to image output is negatively charged, and is cleaned. 4 to each
The transfer units 13Y, 13M, 13C and 13K for the two stations 8Y, 8M, 8C and 8K have, for example, -1.5
By applying a voltage of kv to a part or all of the four stations, the patch image on the belt is transferred to the photosensitive drum 9 of each station as shown by an arrow 22, and is applied to each photosensitive drum cleaner 14. Collected.

However, depending on the change in the surface properties of the transfer / conveyance belt 7 after long-term use or the density of the density correction control toner image, it may not be possible to completely clean the toner image, and the toner remaining on the transfer / conveyance belt 7 is transferred. The recording paper will be stained on the back.

To prevent this, the residual toner on the transfer / conveying belt 7 is detected by the density detecting optical sensor 20, and the cleaning operation is repeated until the level reaches a level at which no back stain occurs. Output without back stains becomes possible.

The control in the first embodiment will be described below with reference to the flowchart shown in FIG.

Step 0 Image formation output command START step 1 Start of patch image creation step 2 Detects a patch image with a sensor and performs image density correction control.

Step 3 In order to return the patch image to the photosensitive drum, a predetermined bias is applied to the transfer device to rotate the transfer conveyance belt.

Step 4 The sensor detects the amount of toner on the transfer / transport belt, and repeats step 3 if the residual toner has not been reduced to a predetermined amount. If the amount has been reduced to the predetermined amount, the process proceeds to step 5.

Step 5 Image formation is started based on the correction result after the detection of the patch image, and a required image is obtained.

Step 6 ends.

(Second Embodiment) FIG. 2 shows a second embodiment.

The image forming apparatus of the present embodiment is configured substantially in the same manner as the conventional image forming apparatus shown in FIG. 6, and is the same as the conventional example shown in FIG. Shows only the main part, and the characteristic cleaning process will be described below.

In the image forming apparatus shown in FIG.
And cleaned.

However, depending on the change in the surface properties of the transfer conveyance belt 7 after long-term use or the density of the density correction control toner image, cleaning may not be performed completely and may pass through the cleaning device, and may remain on the transfer conveyance belt. The removed toner causes stain on the back of the transfer recording paper.

In order to prevent this, the residual toner on the transfer / conveyance belt 7 is detected by the density detecting optical sensor 20 and the cleaning operation is repeated until the toner stain on the transfer / conveyance belt 7 reaches a level at which no back stain occurs. Get the performance you need.

The cleaning device 17 is capable of operating the cleaning condition changing cam 23 to adjust the blade pressure at which the cleaning blade 17a comes into contact with the transfer / conveyance belt 7, and further improves the cleaning conditions such as increasing the blade pressure. The required performance can also be obtained by changing to a higher direction.

The control in the second embodiment will be described below with reference to the flowchart shown in FIG.

Step 0 Image formation output command START step 1 Start of patch image creation step 2 Detects patch images with a sensor and performs image density correction control.

Step 3 The patch image passes through the cleaning unit. Step 4 The amount of toner on the transfer / transport belt is detected by the sensor, and if residual toner is detected, Step 3 is repeated. Alternatively, the cleaning conditions are changed. If no residual toner is detected, the process proceeds to step 5. Step 5 Image formation is started based on the correction result after the patch image detection, and a required image is obtained.

Step 6 ends.

(Third Embodiment) FIG. 3 shows a third embodiment.

FIG. 3 showing the configuration of an image forming apparatus according to the third embodiment is the same as the configuration of the prior art shown in FIG. 6 except for the fur brush cleaning device 24, so that the description of the configuration is omitted. The cleaning process will be described.

In the image forming apparatus shown in FIG. 3, the patch image 21 on the transfer conveyance belt 7 is cleaned by the fur brush cleaning device 24 and collected.

However, depending on the change in the surface properties of the transfer conveyance belt 7 after long-term use or the density of the density correction control toner image, cleaning may not be performed completely and the toner may pass through the cleaning device, and may remain on the transfer conveyance belt. The removed toner causes stain on the back of the transfer recording paper.

To prevent this, the residual toner on the transfer / conveyance belt 7 is detected by the density detection optical sensor 20, and the above-described cleaning operation is repeated until the toner contamination on the transfer / conveyance belt 7 reaches a level at which back contamination does not occur. Get the performance you need.

Further, by increasing the voltage applied to the fur brush 24a or adjusting the amount of overlap with the transfer / transport belt 7 by driving the cleaning condition changing cam 23, the cleaning ability is changed in the direction of higher cleaning ability. The required performance can also be obtained.

The control according to the third embodiment is the same as that of the flowchart of the second embodiment shown in FIG.

In the present embodiment, the cleaning means is classified into one using electrostatic attraction force, one using a blade, a fur brush, and one using electrostatic attraction force by a bias applied to the fur brush. However, the cleaning means can be executed not only independently but also in combination.

The order of image formation in the process is yellow, magenta, cyan, and black, but the order is not limited to this and may be arbitrary. Further, it goes without saying that the present invention is not limited to a full-color image output device, but may be applied to a mono-color image output device having only one process or a double-color image output device having two processes.

[0060]

As described above, according to the image forming apparatus of the present invention, even if the control toner image is directly transferred to the transfer material carrier, the toner stain on the transfer material carrier can be reliably cleaned. Therefore, it is possible to provide an image forming apparatus that does not cause back contamination on the transfer material for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a color image forming apparatus according to a first embodiment.

FIG. 2 is a schematic diagram illustrating a main part of a color image forming apparatus according to a second embodiment.

FIG. 3 is a schematic diagram of a main part of a color image forming apparatus according to a third embodiment.

FIG. 4 is a flowchart showing the operation of the first embodiment.

FIG. 5 is a flowchart showing the operation of the second embodiment.

FIG. 6 is a schematic diagram of a conventional image forming apparatus.

[Description of Signs] 1 ... Recording paper 2 ... Supply section 3 ... Ejection section 4 ... Paper passing path 5 ... Belt driving roller 6 ... Belt driven roller 7 ... Transfer and conveyance belt 8 ... Electrophotographic processing section 9 ... Photoconductor drum 10 ... Charging device 11 ... Exposure device 12 ... Developing device 13 ... Transfer device 14 ... Cleaner unit 15 ... Fixing unit 16 ... Sheet feeding roller 17 ... Belt cleaner 18 ... Control unit 20 ... Optical density sensor 21 ... Density detecting toner image (patch) Image) 22: Patch image collection direction 23: Cleaning condition change cam

Claims (12)

[Claims] 1. A toner image obtained by developing a latent image formed on a latent image carrier by an image exposing means by a developing means and transferring the toner image to a transfer material carried on the transfer material carrier via a transfer means. Then, the surface of the transfer material carrier is cleaned by a cleaning unit, and the control toner image formed on the latent image carrier is transferred to the transfer material carrier, and is read by a density detection sensor. In the image forming apparatus, the cleaning control by the cleaning unit is performed according to a detection output of the density detection sensor. 2. A multi-color image forming station for obtaining a toner image by developing a latent image formed on a latent image carrier by an image exposing means by a developing means, and transferring a transfer material to be carried by the image forming station. An endlessly rotating transfer material carrier that conveys the toner image from the image forming station of each color to the transfer material at the transfer site, and sequentially transfers the toner images of each color to the transfer material. A color image is formed by overlapping, and the surface of the transfer material carrier is cleaned by a cleaning unit.
In an image forming apparatus in which a control toner image formed on a latent image carrier of each of the stations is transferred to the transfer material carrier and is read by a density detection sensor, the detection output of the density detection sensor An image forming apparatus, wherein cleaning control is performed by the cleaning unit in response. 3. The image forming apparatus according to claim 1, wherein the cleaning unit is a cleaning device using an electrostatic attraction force. 4. The cleaning device according to claim 1, wherein the cleaning unit is a cleaning device using a blade.
Or the image forming apparatus according to 2. 5. The image forming apparatus according to claim 1, wherein the cleaning unit is a cleaning device using a fur brush and a bias applied thereto. 6. The image forming apparatus according to claim 1, wherein the cleaning unit performs cleaning control for rotating the transfer material carrier until a predetermined density is reached. 7. The image forming apparatus according to claim 3, wherein the cleaning unit performs cleaning control by changing an electrostatic attraction force. 8. The image forming apparatus according to claim 4, wherein the cleaning unit performs cleaning control by adjusting a contact pressure at which the blade contacts the transfer material carrier. 9. The cleaning device according to claim 5, wherein the cleaning device controls the contact pressure of the fur brush in contact with the transfer material carrier and performs cleaning control by changing an applied bias. Image forming device. 10. The cleaning device according to claim 1, wherein the cleaning unit is a cleaning device that combines a system using an electrostatic attraction force, a system using a cleaning blade, and a system using a fur brush and its applied bias. The image forming apparatus according to claim 1. 11. A toner image obtained by developing a latent image formed on a latent image carrier by an image exposing means by a developing means and transferring the toner image to a transfer material carried on the transfer material carrier via a transfer means. The control toner image formed on the latent image carrier is transferred to the transfer material carrier and read by a density detection sensor, and the toner on the transfer material carrier is transferred to the latent image carrier. In the image forming apparatus which is re-transferred to the carrier and cleaned by the cleaning means for the latent image carrier, the cleaning is performed by executing the re-transfer operation until the detection output of the density detection sensor reaches a predetermined value. An image forming apparatus comprising: 12. A multi-color image forming station for obtaining a toner image by developing a latent image formed on a latent image carrier by an image exposing means with a developing means, and transferring a transfer material to be carried by the image forming station. An endlessly rotating transfer material carrier that conveys the toner image from the image forming station of each color to the transfer material at the transfer site, and sequentially transfers the toner images of each color to the transfer material. A color image is formed by overlapping, and the control toner image formed on the latent image carrier of each of the stations is transferred to the transfer material carrier and read by a density detection sensor. An image to be re-transferred to the toner on the transfer material carrier to all of the latent image carriers or any of the latent image carriers, and to be cleaned by the latent image carrier cleaning unit. The image forming apparatus according to claim 1, wherein the retransfer operation is performed until the detection output of the density detection sensor reaches a predetermined value to perform cleaning.