JPH10288895A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the cleaning performance of the whole of an image forming device by making the transfer conditions from an image carrier to a transfer paper carrier of a toner concentration measuring/controlling pattern image different from the transfer conditions in an image region. SOLUTION: The toner concentration measuring and controlling pattern image formed in a non-image region on a photoreceptor 1 is detected by a toner concentration detector 15 on the photoreceptor 1, so that image forming and transferring conditions are controlled by a process control means based on the result of the detection. In this case, for uniformly inputting toner into each cleaning unit, the transfer conditions when the toner concentration measuring and controlling pattern image formed in the non-image region is transferred to an intermediate transfer belt 10 from the photoreceptor 1 and to a paper transfer unit 11 from the intermediate transfer belt 10 are made different from the transfer conditions in the image region, in transferring a normal image, respectively. Thus, the quantity of the toner remaining after the transfer is almost equal to that of the toner after being transferred to the paper transfer unit 11.

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 using an electrophotographic system, such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, urethane rubber has been used as a device for cleaning toner adhered to an image carrier (photosensitive member, etc.) and a transfer paper carrier (transfer roller, transfer belt, transfer drum, etc.) by the next image forming cycle. There is a blade cleaning system in which the edge of a blade is pressed against the toner to scrape off the toner, and a fur brush cleaning system using a bristle brush. Particularly, the blade cleaning method is widely used because it is mechanically simple and inexpensive.

However, in the case of the blade cleaning method, the blade is chattered with the blade due to the coefficient of friction between the blade and the material of the other side (image carrier or the like) which is in pressure contact with the blade, in addition to the toner removing property which is an original function of the cleaning device. And turning over may occur. In this case, it is usual to adjust the conditions based on the contact angle and contact pressure of the blade. However, the margin of the toner removal capability, which is the original function, is often lost. In particular, most of the pattern images for toner concentration measurement and control used to control the toner concentration and the amount of toner attached to the image forming apparatus are solid images with a large amount of toner attached and are not transferred to transfer paper. Since the image is input to the cleaning blade, there is a possibility that a cleaning failure may occur in a cleaning condition where the toner removing ability is not so large.
It has been difficult to achieve both toner removal properties and conditions for preventing chattering and curling of the blade.

[0004]

In recent years, in addition to an image carrier (photoreceptor or the like) that carries a toner image obtained by visualizing an electrostatic latent image, an intermediate transfer body (an intermediate member) carrying a toner image superimposed thereon has been developed. A transfer belt (transfer belt, intermediate transfer drum, etc.) and a transfer paper carrier (transfer roller, transfer belt, transfer drum, etc.) for carrying and transporting the transfer paper are provided in one image forming apparatus, and a cleaning device is held in each of them. Therefore, in each of the cleaning devices, the margin of the cleaning ability is different depending on the application and the partner (image carrier or the like). However, the above-described pattern image for toner density measurement and control is transferred to the non-image area under the same transfer conditions as the image area, so that the solid image is always removed by the cleaning device at the end. Cleaning performance has been required. At this time, since the cleaning device at the end does not always have higher cleaning performance than the other cleaning devices, there is a possibility that the cleaning may be defective as described above.

The present invention has been made in view of the above-described problems, and has been made in consideration of the amount of toner remaining after transfer of a pattern image for measuring and controlling the toner density on an image carrier, and the amount of the pattern image transferred onto a transfer paper carrier. An object of the present invention is to stabilize the cleaning performance of the entire image forming apparatus by controlling the amount of toner and removing a toner image with a large amount of toner adhered by a cleaning device having a sufficient cleaning ability.

[0006]

According to a first aspect of the present invention, there is provided an image bearing member for carrying a toner image obtained by visualizing an electrostatic latent image, and a transfer sheet for carrying the transfer paper. Having at least a transfer paper carrier for transferring and transporting the toner image to the transfer paper, and having a cleaning device for removing toner, paper dust and the like on each of the image carrier and the transfer paper carrier, and And a toner density detecting means for detecting the density of the pattern image for measuring and controlling the toner density formed in the non-image area of the image carrier. The transfer condition from the image carrier to the transfer paper carrier is different from the transfer condition of the image area, whereby the transfer of the pattern image for measuring and controlling the toner concentration on the image carrier is performed. Remaining toner amount and To enable control the amount of toner transferred pattern image on the transfer sheet carrying member is one to stabilize the cleaning performance of the entire image forming apparatus.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the toner density is measured and controlled from the image carrier to the transfer paper carrier by the number of images (the number of copies or prints). The transfer condition of the pattern image for measuring and controlling the toner concentration on the image carrier according to the aged deterioration of the cleaning member. In addition, the amount of toner of the pattern image transferred onto the transfer paper carrier can be changed and controlled, and the cleaning performance of the entire image forming apparatus over time can be stabilized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a view showing an example of an image forming apparatus according to the present invention, and is a view showing a schematic configuration around a photosensitive member of a color image forming apparatus. When the color image forming apparatus is a digital color copying machine, for example, a color image reading apparatus (hereinafter, referred to as a color scanner) is provided, and the color scanner scans the original image with blue (B), green (G), The read image signal is read for each color separation of red (R), and the read image signal is processed by an image processing unit to be converted into black (Bk), cyan (C), magenta (M), and yellow (Y) image data. The image data is transmitted to an optical writing device (not shown) such as a device that performs optical writing by scanning a laser beam with an optical deflector such as a rotary polygon mirror or a device that performs optical writing by using an LED array. The apparatus converts the image data into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on the photoconductor 1 as an image carrier.

The photoreceptor 1 rotates counterclockwise as indicated by the arrow in the figure. Around the photosensitive member, a charger 2,
Bk developing device 3, C developing device 4, M developing device 5, Y developing device 6,
A toner density detecting device 15, an intermediate transfer belt 10, a pre-cleaning neutralizer 7, a photoreceptor cleaning device 8, and a neutralizing lamp 9 are arranged. Further, the intermediate transfer belt 10 is stretched around a driving roller or a driven roller and rotates clockwise as indicated by an arrow in the figure, so that the toner image formed on the photoconductor 1 is transferred. Around the intermediate transfer belt 10, a paper transfer device 11, an intermediate transfer belt cleaning device 12, and a lubricity imparting agent application device 13 are arranged. The paper transfer unit 11 includes a transfer roller 11-2 and a cleaning blade 1
1-1, and a contact / separation mechanism 11 for the intermediate transfer belt 10
-3.

Here, a series of image forming processes by the color image forming apparatus will be described. First, the original is a monocolor original, and the image data of the original read by the color scanner is monochromatic image data, and any one of the Bk developing unit 3, the C developing unit 4, the M developing unit 5, and the Y developing unit 6 A case where an image can be formed by using one of them, for example, a case where a document image is formed by a Bk developing unit 3 as a monochrome image will be described.

In FIG. 1, the charger 2 rotates in the direction of the arrow.
Is written on the photoreceptor 1 charged by the above with a writing light L from an optical writing device (not shown) in accordance with image data to form an electrostatic latent image, and then is developed by a Bk developing device 3 to adhere toner. Then, the electrostatic latent image is visualized. Then, the visualized toner image on the photoconductor 1 is transferred onto the intermediate transfer belt 10 rotating in the direction of the arrow in the figure (referred to as intermediate transfer). After the intermediate transfer, the photoconductor 1 is neutralized by the pre-cleaning static eliminator 7, the remaining toner is removed by the photoconductor cleaning device 8, and further neutralized by the static elimination lamp 9. The toner image transferred onto the intermediate transfer belt 10 is transferred to a transfer roller 11-
The paper is transferred onto a transfer paper carried and transported by 2 (referred to as paper transfer). Then, the transfer paper on which the toner image has been transferred is transported by the transport device 16 to a fixing device (not shown), and the toner image is fixed on the transfer paper. Further, the transfer residual toner on the intermediate transfer belt 10 after the paper transfer is completed is removed by the intermediate transfer belt cleaning device 12. These series of operations are repeated a number of times according to the number of originals and the set number of copies.

Next, the image data of the original read by the color scanner is a plurality of colors, and a plurality of developing devices among the Bk developing device 3, the C developing device 4, the M developing device 5, and the Y developing device 6 are used. An example in which an image cannot be formed unless otherwise, for example, a case where a document is a color document and a color image is formed by four types of developing units will be described.

In FIG. 1, first, a portion of a Bk developing unit 3 to be developed with black (Bk) toner is read by a color scanner, and is placed on a photosensitive member 1 charged by a charger 2 in accordance with the read image data. An optical latent image was formed by performing optical writing with a writing light L from an optical writing device (not shown), developed by a Bk developing device 3 and adhered with Bk toner to visualize the electrostatic latent image, and visualized. The Bk toner image on the photoconductor 1 is intermediately transferred onto the intermediate transfer belt 10. After completion of the intermediate transfer, the photoconductor 1 is neutralized by the pre-cleaning static eliminator 7, the transfer residual toner is removed by the photoconductor cleaning device 8, the static elimination is performed by the static elimination lamp 9, and then charged by the charger 2. Next, a portion of the C developing device 4 to be developed with cyan (C) toner is read by a color scanner, and an electrostatic latent image is formed on the photoconductor 1 in the same manner as described above. Then, the electrostatic latent image is visualized by adhering the C toner, and the visualized C toner image on the photoconductor 1 is intermediately transferred onto the intermediate transfer belt 10. Thereafter, the same latent image forming and developing steps are performed for magenta (M) and yellow (Y) as described above, and the intermediate transfer is performed on the intermediate transfer belt 10 in the order of the M toner image and the Y toner image.

On the intermediate transfer belt 10, Bk (black), C (cyan), M (magenta), Y (yellow)
And the superposed toner image is transferred to a transfer sheet carried and conveyed by a transfer roller 11-2 of the sheet transfer device 11. The transfer paper onto which the four color toner images have been transferred is transported by the transport device 16 to a fixing device (not shown), and the toner images are fixed on the transfer paper. Further, the transfer residual toner on the intermediate transfer belt 10 after the paper transfer is completed,
It is removed by the intermediate transfer belt cleaning device 12.
These series of operations are repeated a number of times according to the number of originals and the set number of copies.

The image forming apparatus shown in this embodiment is provided with a process control means, which comprises a microcomputer, a RAM,
It comprises a memory such as an OM, an input / output circuit, an A / D converter, a clock, a counter, various control circuits, etc., and controls the driving operation of each part of the image forming apparatus. Image forming conditions such as a developing bias, a laser beam power for forming a latent image on the photoconductor,
In addition, transfer conditions at the time of intermediate transfer and paper transfer are controlled. These image forming and transfer conditions are as follows. As shown in FIG. 2, a pattern image for toner density measurement and control formed on a non-image area on the photoconductor 1 is And controlled by the process control means based on the detection result.

The laser beam power when writing a pattern image for the toner concentration measurement and control on the photosensitive member 1 is changed to several levels to weak from the strong one, for example, Pw ₁ ~Pw ₁₀
Up to 10 steps are performed for each color to create 10 pattern images for toner density measurement and control. At this time, a pattern image is created in a non-image area on the photoconductor 1 as shown in FIG. 2, and any one of the Bk developing unit 3, the C developing unit 4, the M developing unit 5, and the Y developing unit 6 The image is visualized by a developing device and transferred onto the intermediate transfer belt 10, but since the pattern image is created in a non-image area, the photoconductor cleaning device 8, the intermediate transfer belt cleaning device 12, or the paper transfer device 11 The solid image is input to any of the cleaning blades 11-1. In this case, since the load on the cleaning device is large, in the present invention, the toner density measurement / control pattern image created in the non-image area is formed so that the toner is input to each of the cleaning devices evenly. Transfer conditions when transferring from the photoreceptor 1 to the intermediate transfer belt 10, and
The transfer conditions at the time of transfer from the intermediate transfer belt 10 to the paper transfer unit 11 (transfer roller in the illustrated example) are different from the transfer conditions of the image area at the time of transferring a normal image.

Specifically, transfer conditions as shown in Table 1 below are set, and the optimum transfer bias for transferring a normal image from the photosensitive member 1 to the intermediate transfer belt 10 is set to +14.
When the voltage is set to 00 V, and when the pattern image is transferred, +80 is applied.
0V, when the optimum transfer bias for transferring the normal image from the intermediate transfer belt 10 to the transfer paper is + 1200V, and when transferring the pattern image to the paper transfer device 11,
It has been changed to 800V. By doing so, the photoreceptor 1
The transfer residual toner amount of the upper pattern image and the intermediate transfer belt 1
The transfer residual toner amount above zero and the toner amount transferred to the paper transfer device 11 become substantially equal.

[0019]

[Table 1]

In addition to this, when there is a cleaning device having a better cleaning ability than other cleaning devices, for example, in the present embodiment, the photosensitive member cleaning device 8 includes a fur brush in addition to the cleaning blade 8-1. 8-2, the cleaning ability is usually superior to that of the intermediate transfer belt cleaning device 12 and the cleaning blade 11-1 of the paper transfer device, which are cleaned only by the cleaning blade. In such a case, Photoconductor 1
The transfer conditions may be set so that the upper transfer residual toner amount is larger than the transfer residual toner amount of the intermediate transfer belt 10 or the toner amount transferred to the paper transfer device 11. Table 2 below shows an example of the setting of the transfer conditions when the cleaning device has a superior difference.

[0021]

[Table 2]

On the other hand, the cleaning performance of the photoconductor cleaning device 8, the cleaning blade 11-1 of the paper transfer device 11, and the cleaning performance of the intermediate transfer belt cleaning device 12 do not all deteriorate in the same manner. In this case, in accordance with the number of images to be formed (the number of copies), transfer conditions for transferring the pattern image for measuring and controlling the toner density from the photoreceptor 1 to the intermediate transfer belt 10 and the transfer conditions from the intermediate transfer belt 10 to the paper transfer device 11 may be set as transfer conditions. For example, if the number of copies from the time when a cleaning member is new to the time when the next cleaning member is replaced is assumed to be 80,000, and when the number of copies is in the first half period, the amount of transfer residual toner on the photoconductor 1 is reduced by intermediate transfer. The transfer condition is set so as to be larger than the transfer residual toner amount of the belt 10 and the toner amount transferred to the paper transfer device 11, and when the number of copies is in the latter half period, the transfer condition is set to be opposite to the above. As described above, the transfer condition at the time of transferring the pattern image may be changed according to the number of copies. Table 3 below shows examples of setting the transfer conditions when the transfer conditions are changed according to the number of copies.

[0023]

[Table 3]

In the above-described embodiment, a system in which four-color developing units are provided, and the toner image on the photoreceptor 1 is intermediately transferred to the intermediate transfer belt 10 and then transferred to paper by the paper transfer unit 11 is used. Although a color image forming apparatus has been described as an example, the present invention relates to FIG.
However, the present invention is not limited to this configuration, and the present invention can be similarly applied to a color image forming apparatus having another configuration or a normal single-color image forming apparatus. That is, an image carrier (a photoreceptor, an intermediate transfer body (intermediate transfer belt, an intermediate transfer drum), etc.) that carries a toner image, and a transfer paper carrier that carries a transfer paper, transfers the toner image to the transfer paper, and conveys the toner image (Transfer belt, transfer roller,
The present invention is similarly applicable to any image forming apparatus having at least a transfer drum or the like, and having a cleaning device for removing toner, paper dust, and the like on each of the image carrier and the transfer paper carrier. Can be implemented.

[0025]

As described above, in the image forming apparatus according to the first aspect, the transfer condition between the image created in the image area and the pattern image for toner density measurement and control created in the non-image area is determined. By setting different conditions, it is possible to control the amount of transfer residual toner of the pattern image on the image carrier and the amount of toner of the pattern image transferred on the transfer paper carrier, and stable cleaning performance of the entire image forming apparatus Can be changed.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the transfer condition of the pattern image for measuring and controlling the toner density from the image carrier to the transfer paper carrier is changed depending on the number of images formed. Therefore, the amount of toner remaining on the image carrier transfer of the pattern image for toner concentration measurement and control and the amount of toner of the pattern image transferred onto the transfer paper carrier can be changed and controlled according to the aged deterioration of the cleaning member. Thus, the cleaning performance over time of the entire image forming apparatus can be stabilized.

[Brief description of the drawings]

FIG. 1 is a view illustrating an example of an image forming apparatus according to the present invention, and is a view illustrating a schematic configuration around a photoconductor of a color image forming apparatus.

FIG. 2 is a diagram illustrating a relationship between a pattern image for toner density measurement and control created in a non-image area of a photoconductor and a normal image in an image area.

[Explanation of symbols]

 1: Photoreceptor 2: Charger 3: Bk developing device 4: C developing device 5: M developing device 6: Y developing device 7: Static eliminator before cleaning 8: Photoconductor cleaning device 8-1: Cleaning blade 8-2: Fur brush 9: Static elimination lamp 10: Intermediate transfer belt 11: Paper transfer device 11-1: Cleaning blade 11-2: Transfer roller 11-3: Contact / separation mechanism 12: Intermediate transfer belt cleaning device 12-1: Cleaning blade 13: Lubricity imparting agent application device 15: Toner concentration detection device 16: Transport device

Claims (2)

[Claims] An image carrier that carries a toner image obtained by visualizing an electrostatic latent image; and a transfer paper carrier that carries a transfer paper, transfers the toner image to the transfer paper, and transports the toner image. A cleaning device for removing toner, paper dust and the like on each of the image carrier and the transfer paper carrier, and a toner density measurement / control pattern formed in a non-image area of the image carrier. An image forming apparatus having at least a toner density detecting means for detecting the density of an image, wherein a transfer condition of the pattern image for measuring and controlling the toner density from the image carrier to a transfer paper carrier is a transfer condition of an image area. An image forming apparatus characterized by different conditions. 2. The image forming apparatus according to claim 1, wherein the transfer condition of the pattern image for measuring and controlling the toner density from the image carrier to the transfer paper carrier is changed depending on the number of images to be formed. An image forming apparatus comprising: