JP2011059320A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can promptly suppress a failure caused due to decrease of a lubricant application amount without causing complication and cost increase of configuration, even when an image with high image area ratio is formed in a low line speed mode. <P>SOLUTION: The image forming apparatus has a control means 30 for adjusting an inter-sheet distance between recording media, based on an image area value of the image to be formed on a recording medium under paper passing in the low line speed mode. The control means 30 calculates an inter-sheet extension ratio based on the image area value by image data from an image processing part 31, to set the inter-sheet distance corresponding to the inter-sheet extension ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a plotter, and a multi-function machine provided with at least one of these, and more specifically, a lubricant applying means for applying a lubricant to the surface of an image carrier. The present invention relates to an image forming apparatus.

In general, an electrophotographic apparatus irradiates a uniformly charged image carrier (photosensitive member) with writing light modulated by image data to form an electrostatic latent image on the photosensitive member. Toner is supplied to the photosensitive member on which the electrostatic latent image is formed by a developing means to make a visible image as a toner image.
After the toner image on the photoconductor is transferred to transfer paper (recording paper or intermediate transfer body) at the transfer section, the toner transferred onto the transfer paper at the fixing section is fixed by heating and pressurization, and remains on the surface of the photoconductor. The toner is collected by a method such as scraping with a cleaning blade at the cleaning unit. The image forming process is as described above.

In the cleaning section, a cleaning blade made of an elastic material such as rubber has been widely used as a cleaning means for residual toner, but this is because the structure of the cleaning device using the cleaning blade is simple and small, and the cost is low. This is because it is advantageous from the aspect.
As a material of the cleaning blade, polyurethane rubber which is a kind of thermoplastic elastomer is mainly used from the viewpoints of chemical resistance, wear resistance, moldability, mechanical strength, and the like.
In this type of image forming apparatus, a lubricant is applied to the photoconductor for the purpose of improving the cleaning property, making the image uniform, improving the transfer efficiency, and improving the wear resistance of the photoconductor.
By applying the lubricant, the surface friction coefficient of the photoreceptor decreases, and the surface of the photoreceptor is constantly refreshed by repeating the application and scraping operation of the lubricant. Fluidity is maintained.

When the surface friction coefficient of the photoconductor decreases, the progress of wear on the surface of the photoconductor and the edge of the cleaning blade is suppressed, the wear resistance of the photoconductor is improved, and the cleaning performance is prevented from being deteriorated. Further, the adhesion force between the toner and the photoconductor is reduced, the non-attached toner in the non-image area is reduced, and the toner on the transfer paper is prevented. In addition, the toner image can be easily transferred to the transfer paper, the worm-like transfer white spots that are likely to occur in the line image are reduced, the transfer electric field is reduced, and the toner image carrier due to the peeling discharge when the transfer paper is peeled off. Reattachment to is prevented.
When the surface of the photoconductor is constantly refreshed by repeating the application of the lubricant and the scraping operation, the fine powder additive in the toner is prevented from adhering to the photoreceptor surface. The resin grows into spindle-shaped spots and is developed without being removed by the charge removal in the exposure process to deteriorate the image quality and prevent the cleaning blade edge from being damaged.
When the lubricant adheres to the toner and the fluidity of the collected toner is maintained, it is prevented that the toner is fixed and the conveyance path and the cleaning unit are damaged due to the decrease in fluidity and pressure heating. Thus, various excellent effects can be obtained by applying the lubricant.
As a constitution of the lubricant application means, generally, a bar-like or block-like lubricant made of zinc stearate or the like is scraped with a lubricant application brush and adhered to the surface of the photoreceptor.

By the way, an image that requires high resolution (eg, normal 600dpi to 1200dpi) and a low linear velocity mode (eg, an image creation linear velocity of 180mm / s) that passes at a lower linear speed than usual to achieve cardboard feeding. (90mm / s), it is known that the amount of lubricant applied to the photoreceptor is lower than normal speed because the lubricant application brush reduces the rotational speed and reduces the lubricant polishing ability. .
On the other hand, it is known that the amount of lubricant applied from the lubricant applying means to the photoreceptor is reduced even when an image having a high image area ratio is formed.
For this reason, when an image having a high image area ratio is formed in the low linear velocity mode as described above, it becomes difficult to obtain a lubricant coating amount equivalent to that in the normal mode, and as a result, the blade squealing due to an increase in the friction coefficient of the photosensitive member. In addition, there is a concern that defects such as so-called medaka images, filming, primary transfer, and worm-eaten images generated between photoconductors due to silica adhesion or the like may occur.
Patent Document 1 discloses that a means for detecting the vibration of the cleaning blade is provided, and the amount of lubricant supplied to the surface of the image carrier is controlled based on the detection signal.

In the countermeasure described in Patent Document 1, it is necessary to newly add a mechanism for controlling the lubricant supply amount, so that the configuration becomes complicated and an increase in cost cannot be avoided.
Further, since the detection of the vibration of the cleaning blade is used as a trigger, the pattern to which the lubricant is to be supplied is limited, and it has been difficult to maintain the function of suppressing the increase in the friction coefficient on the surface of the photosensitive member substantially constant.
Further, since the supply amount of the lubricant is changed after the vibration of the cleaning blade is detected, there is a problem that the response of the countermeasure is low.

  The present invention has been made in view of such a current situation, and even when an image having a high linear area ratio and a high image area ratio is formed, the lubricant application can be performed without complicating the configuration and increasing the cost. An object of the present invention is to provide an image forming apparatus that can quickly suppress problems caused by a decrease in the amount.

  In order to achieve the above object, the invention described in claim 1 includes an image carrier, charging means for charging the image carrier, exposure means for forming an electrostatic latent image on the image carrier, and the image. Developing means for visualizing the electrostatic latent image formed on the carrier, cleaning means for cleaning the surface of the image carrier, and lubricant application means for applying a lubricant to the surface of the image carrier; In an image forming apparatus having a low linear velocity mode for passing paper at a lower linear velocity than the imaging linear velocity mode in addition to one imaging linear velocity mode, And a control means for adjusting the distance between the recording media based on the image area value of the image formed on the recording medium.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control unit calculates a paper gap extension rate based on the image area value, and sets a paper gap distance corresponding to the paper gap extension rate. It is characterized by doing.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, when there is a paper-to-paper distance due to the paper-to-paper extension calculated by other control, the control means calculates based on the image area value. The longer distance between the papers is set by comparing the distance between the papers due to the extension between the papers and the distance between the papers according to the other control calculated by the other control.
According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the lower limit value of the inter-sheet extension rate calculated based on the image area value is set to 100%. .

According to the present invention, when a low linear velocity mode and a high image area are input, it is possible to perform sufficient lubricant application by extending the interval between papers suitable for each image area, and suppress an increase in the photosensitive member friction coefficient. be able to.
Since the interval between sheets is extended by using the image area value during paper feeding as a trigger, the lubricant application level can be stabilized with higher accuracy than the conventional method using the blade vibration detection as a trigger.
Since the lubricant application amount is adjusted by adjusting the paper interval, it is possible to suppress a complicated configuration and an increase in cost.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is an enlarged view of a process cartridge. It is a control block diagram. 6 is a graph showing the relationship between the image area cumulative average MAX value and the inter-paper extension rate D. 6 is a graph showing the relationship between the image area cumulative average MAX value and the inter-paper extension rate D when the lower limit value of the inter-paper extension rate is fixed at 100%.

Embodiments of the present invention will be described below with reference to the drawings.
First, an outline of the configuration of a four-tandem intermediate transfer type color copier as an image forming apparatus according to the present embodiment will be described with reference to FIG.
In FIG. 1, reference numeral 100 denotes an image forming means, and 200 denotes an intermediate transfer means. The image reading means installed on the image forming means 100 is not shown.
The image forming means 100 includes four image forming stations of yellow (Y), cyan (C), magenta (M), and black (K). Each image forming station has the same configuration, and a drum-shaped photoreceptor 1 serving as a carrier that rotates counterclockwise is arranged in parallel.
When the symbols for each color are abbreviated, a charging roller 3 as a charging unit, a developing device 2 as a developing unit, and a toner image formed on each photosensitive drum 1 around each photosensitive member 1 are described later. A primary transfer roller 5 as a primary transfer means for transferring to an intermediate transfer belt 4 as a transfer body, and a primary cleaning device 6 also serving as a lubricant applying means are arranged. Each primary transfer roller 5 is pressed against the photosensitive member 1 by a biasing member (not shown) with the intermediate transfer belt 4 sandwiched between them at the primary transfer position.
Each developing device 2 contains color toners of different colors. On each image forming station, an optical writing device 11 (Y, C, M, K) is provided as exposure means.

In the intermediate transfer means 200, an endless belt-like intermediate transfer belt 4 is wound around a driving roller 21, a driven roller 22, and a secondary transfer counter roller 23 so as to be able to run clockwise in the drawing.
A belt cleaning device 24 that cleans the surface of the intermediate transfer belt 4 is provided at a portion facing the driven roller 22.
A secondary transfer roller 25 as a secondary transfer unit is provided at a position opposite to the secondary transfer counter roller 23. The secondary transfer roller 25 is in contact with the toner image carrying surface of the intermediate transfer belt 4 while being pressed toward the secondary transfer counter roller 23 by a pressing spring (not shown) to form a pressure contact portion that is a secondary transfer nip. Yes.
A secondary transfer bias is applied to the secondary transfer roller 25 by a power source (not shown), and a secondary transfer electric field is formed in the secondary transfer nip positioned between the secondary transfer counter roller 23 and the ground.

As shown in FIG. 2, the photosensitive member 1 and the above-described members around the photosensitive member 1 are integrally accommodated in a process cartridge 300 that is detachable from the apparatus main body.
That is, the process cartridge 300 includes a photosensitive member 1, a charging roller 3 as each process means, a developing device 2, and a primary cleaning device 6 in a casing 310 (shown in a simplified manner in FIG. 1).
In this embodiment, the process cartridge 300 itself is replaced. However, the process cartridge 300 is removed from the main body of the image forming apparatus, and the like, such as the photosensitive member 1, the charging roller 3, the developing device 2, and the primary cleaning device 6. The structure which replaces | exchanges for a new thing in a unit may be sufficient.

The configuration operation of the toner removing unit and the lubricant applying unit of the primary cleaning device 6 will be described in detail with reference to FIG.
In order from the upstream side in the rotation direction of the photoreceptor 1, the photoreceptor 1 is neutralized by the pre-cleaning neutralization lamp 60, and the toner remaining is removed by the cleaning blade 62 as a removing member while the transfer residual toner is disturbed by the fur brush 61. The toner attached on the fur brush 61 is flickered by the flicker 63.
The toner removed by flicking is transported out of the cleaning device by a transport screw 64. The fur brush 61 rotates in the follower direction as indicated by the arrow with respect to the photoreceptor 1. The entry of the fur brush 61 into the photoconductor 1 represents an apparent bite.

The cleaning blade 62 is fixed to a holder that is rotatably held (not shown), and is supported so as to come into contact with the rotation direction of the photosensitive member 1 in the counter direction. The cleaning blade 62 is pressed against the photosensitive member 1 by a pressure spring (not shown) to remove toner. The photoreceptor 1 from which the toner has been removed by the cleaning blade 62 is coated with zinc stearate as a lubricant by a brush roller-shaped application brush 66 as an application member of the lubricant application means 65.
For the application of zinc stearate, solid zinc stearate 67 held by a guide bracket (not shown) is pressed against the application brush 66 by a pressure spring 68, and the zinc stearate 67 is scraped by the application brush 66 to remove the surface of the photoreceptor 1. It is applied to.
The entry of the application brush 66 into the photoreceptor 1 represents an apparent bite.
On the downstream side of the photosensitive member rotation direction of the lubricant application means 65, there is an application blade 69 as a leveling member comprising a rubber blade for leveling zinc stearate adhering to the photosensitive member 1 in powder form by the application brush 66. It is provided so as to abut on the photoreceptor 1 in the counter direction.
In FIG. 2, symbol LB indicates a laser beam from the optical writing device 11.

  As a lubricant, in addition to zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate , Zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, palmitic acid, cobalt cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, palmitate And relatively higher fatty acids such as calcium acid, lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, and cadmium ricolinolenate. Natural wax such as carnauba wax may also be used.

As shown in FIG. 1, a scanner is mounted on a photoreceptor 1 for each image forming station of Y (yellow), C (cyan), M (magenta), and K (black) uniformly charged by a charging roller 3. The image read in step 1 is color-separated and written for each color to form an electrostatic latent image.
The image forming process will be described using a Y (yellow) station. The latent image formed on the photosensitive member 1 is developed with the developing device 2 in accordance with the Y toner to form a toner image. The developed Y (yellow) toner image is transferred onto the intermediate transfer belt 4 by applying a bias to the primary transfer roller 5 at a portion where the photoreceptor 1 and the intermediate transfer belt 4 are in contact with each other.
In this manner, toner images are formed on the photosensitive member 1 in the same manner in each image forming station in the order of C (cyan), M (magenta), and K (black), and transferred onto the intermediate transfer belt 4. The transfer paper P as a recording medium is fed from a resist roller pair (not shown) at the timing when the toner image reaches the secondary transfer position, and is transferred onto the transfer paper P by the secondary transfer roller 25 at a time.
After the toner image is primarily transferred onto the intermediate transfer belt 4, the transfer residual toner is removed by the primary cleaning device 6, the lubricant is applied by the lubricant applying means 65, and the charging roller 3 is again used. Repeat the operation of charging uniformly.
After the toner image is secondarily transferred to the transfer paper, the transfer residual toner is removed from the intermediate transfer belt 4 by a cleaning device 24 which is a belt cleaning device.

Next, control when the low linear velocity mode is set and an image with a high image area ratio is formed will be described.
As shown in FIG. 3, the control in the present embodiment is performed by the control means 30. As shown in Table 1, the control unit 30 calculates the image area ratio based on the image data information from the image processing unit 31, and calculates the inter-paper extension ratio D from a linear expression based on the variables B and C.
Other values are calculated by using the A4T equivalent inter-paper distance G1 (mm) when the inter-paper extension rate D = 100% as a default value. FIG. 4 is a graph showing the relationship between the image area cumulative average MAX value and the inter-paper extension rate D.

When the low linear velocity mode is set by the operation panel 32 or via a PC (not shown), the control unit 30 transmits image data transmitted from the image processing unit 31 to an image formed on the transfer paper P that is being passed. Based on the image area ratio A, the sheet area extension ratio D is calculated. Based on the inter-paper extension rate D, the inter-paper distance G1 is calculated or extracted from the table, and a known inter-paper distance adjustment operation is performed. That is, for example, the drive of the paper feed roller is controlled, and the start timing of the image forming process is controlled correspondingly.
When low linear velocity mode and high image area are input, by extending the paper interval suitable for each image area calculated from the image area, idle rotation time without toner input can be obtained. As a result, an increase in the coefficient of friction of the photosensitive member can be suppressed.

Next, another embodiment will be described.
In the present embodiment, when there is a paper distance by paper extension calculated by fixing or other control, the control unit 30 determines the paper distance by paper extension calculated based on the image area value and the paper distance. It is characterized in that the longer paper distance is set by comparing with the paper distance calculated by the other control and the paper distance extension.
For example, when there is an inter-paper distance G2 due to the inter-paper extension calculated from the inter-paper extension due to the convenience of fixing (for example, when passing a small size paper), the control means 30 determines based on the inter-paper extension rate D. The lengths of the inter-paper distance G1 and the inter-paper distance G2 are compared, and the longer one is set as the inter-paper adjustment distance.
By adopting the longer one, it is possible to form an image with the optimum distance between papers.

Next, still another embodiment will be described.
The present embodiment is characterized in that the lower limit value of the inter-paper extension rate calculated based on the image area value is set to 100%.
Table 2 shows numerical values when the lower limit E of the inter-paper extension rate is fixed to 100%. In this case, the inter-paper distance G1 is calculated or extracted based on the inter-paper extension rate D1 obtained by fixing the lower limit value to 100%. FIG. 5 is a graph showing the relationship between the image area cumulative average MAX value and the inter-paper extension rate D in the present embodiment.

  By fixing the lower limit E to 100%, the inter-paper extension rate D1 does not become 100% or less, and it is possible to reliably suppress an increase in the photosensitive member friction coefficient.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum as an image carrier 2 Developing device as developing means 3 Charging roller as charging means 6 Primary cleaning device as cleaning means that also serves as lubricant applying means 11 Optical writing device as exposure means 30 Control means

JP 2004-278734 A

Claims (4)

An image carrier, a charging unit for charging the image carrier, an exposure unit for forming an electrostatic latent image on the image carrier, and the electrostatic latent image formed on the image carrier are visualized. A developing unit; a cleaning unit that cleans the surface of the image carrier; and a lubricant application unit that applies a lubricant to the surface of the image carrier. In an image forming apparatus having a low linear velocity mode for passing paper at a lower linear velocity than the image linear velocity mode,
Image forming characterized by having control means for adjusting the inter-paper distance between the recording media based on the image area value of the image formed on the recording medium during paper passing in the low linear velocity mode apparatus. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the control unit calculates an inter-paper extension rate based on the image area value, and sets an inter-paper distance corresponding to the inter-paper extension rate. The image forming apparatus according to claim 2.
When there is an inter-paper distance due to the inter-paper extension calculated by another control, the control unit calculates the inter-paper distance by the inter-paper extension calculated based on the image area value and the other control. An image forming apparatus that compares a distance between sheets by extension between sheets and sets a longer distance between sheets. The image forming apparatus according to claim 2 or 3,
An image forming apparatus, wherein a lower limit value of the inter-paper extension rate calculated based on the image area value is set to 100%.

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