JP2015230327A - Image forming apparatus, image forming method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix images to sheets with high image quality even with the use of a fixing unit having common specification.SOLUTION: An image forming apparatus includes a fixing unit, conveyance means for feeding, after a sheet before image formation is fed to the fixing unit and pre-heated, a sheet having a toner image formed thereon to the fixing unit again, and condition setting means for setting conditions for pre-heating sheets.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a program.

  In the fixing unit of the image forming apparatus, the center of the roller may be thickened to form a drum, or the center of the roller may be thinned to form a knob. This is a method in which an optimum tension is generated on paper by preventing a wrinkle of the paper by providing a speed difference between both ends and the center of the paper passing surface (for example, patent document). 1). When the roller has a claw-like shape, a pulling force is generated from the center of the paper to both ends by passing both ends faster than the center of the paper.

The conventional paper stretching configuration using the pressure roller in the form of a thumb has a problem that image unevenness occurs with respect to paper outside the stretchable area.
For paper that is greatly expanded and contracted in the axial direction, a fixing unit that has improved the stretching effect by increasing the difference in outer diameter as the amount of the tab-shaped pressure roller is used.
However, when the amount of the tab is increased, the trailing edge of the sheet is bounced when the sheet is thin, and an image defect or the like occurs. Therefore, it has not been possible to cope with the fixing unit of the common specification.

  Therefore, an object of the present invention is to fix an image on a sheet with high image quality even when a fixing unit having a common specification is used.

  In order to solve the above problems, the invention described in claim 1 is directed to a fixing unit and a sheet on which a toner image is formed after a sheet before image formation is passed through the fixing unit and preheated. It is characterized by comprising conveying means for passing the paper through the unit again, and condition setting means for setting conditions for preheating the paper.

  According to the present invention, it is possible to fix an image on a sheet with high image quality even if a fixing unit having a common specification is used.

It is a whole lineblock diagram concerning one embodiment. It is explanatory drawing about the conventional normal path | pass (single side | surface). It is explanatory drawing about the conventional normal path | pass (both surfaces). It is explanatory drawing about the preheating (switchback path | route) of this invention. It is explanatory drawing about the preheating (double-sided conveyance path | route) of this invention. It is a flowchart about a comprehensive operation. FIG. 2 is an example of a block diagram illustrating an electrical configuration of the image forming apparatus illustrated in FIG. 1.

<Overview>
An embodiment of the present invention will be described. The present invention has the following characteristics when high image quality is obtained by preheating paper.
In short, the paper shrinks when heated, but has the property of retaining the shape after shrinkage. This shrinkage phenomenon occurs remarkably in film media and the like. Further, the amount of shrinkage or deformation due to heat of the paper tends to decrease.
Therefore, by heating the paper before printing, the paper is shrunk, and printing on the paper after shrinkage can minimize the amount of deformation of the paper, so that high-quality printing is possible.

The present invention will be described in detail below with reference to the drawings.
<Mechanical configuration>
An embodiment in which the present invention is applied to an electrophotographic color copying machine (hereinafter simply referred to as a copying machine) will be described.
FIG. 1 is an overall configuration diagram according to an embodiment.
First, a basic configuration of the copying machine according to the present embodiment will be described.
The copying machine includes an ADF 1 that transports a document, a scanner unit 2 for reading an image of the document, an image forming unit 3 that forms an image based on image data acquired by the scanner unit 2, and an image forming unit 3 And a paper feeding unit 4 for feeding the paper P. ADF is an abbreviation for Auto Document Feeder.

First, the configuration of the image forming unit 3 will be described.
As shown in FIG. 1, the image forming section 3 includes four process units 10K, 10M, 10C, and 10Y that form toner images of black, magenta, cyan, and yellow.
Subscripts K, M, C, and Y indicate black, magenta, cyan, and yellow, respectively.
The process units 10K, 10M, 10C, and 10Y include photoconductors 11K, 11M, 11C, and 11Y, which are image carriers that carry toner images of the respective colors.
Around the photoconductors 11K, 11M, 11C, and 11Y, charging devices 12K, 12M, 12C, and 12Y that uniformly charge the surfaces of the photoconductors 11K, 11M, 11C, and 11Y are disposed. Around the photosensitive members 11K, 11M, 11C, and 11Y, developing devices 13K, 13M, 1C, and 13Y that develop electrostatic latent images formed on the surfaces of the photosensitive members 11K, 11M, 11C, and 11Y are provided. Also, around each photoreceptor 11K, 11M, 11C, 11Y, there is a photoreceptor cleaning device 14K, 14M, 14C, 14Y etc. that cleans the surface of each photoreceptor 11K, 11M, 11C, 11Y after the toner image transfer. I have.

  Process units 10K, 10M, 10C, and 10Y are charging devices 12K, 12M, 12C, and 12Y arranged around the photoconductors 11K, 11M, 11C, and 11Y, developing devices 13K, 13M, 1C, and 13Y, and photoconductor cleaning The devices 14K, 14M, 14C, and 14Y are supported as a unit on a common support. The process units 10K, 10M, 10C, and 10Y are configured to be detachable from the main body of the image forming unit 3.

Further, the image forming unit 3 forms an electrostatic latent image by irradiating a uniformly charged surface of each of the photoreceptors 11K, 11M, 11C, and 11Y with a laser beam corresponding to image information. It has.
The optical writing device 30 includes a laser light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like. The optical writing device 30 irradiates the surface of each of the photoconductors 11K, 11M, 11C, and 11Y that is rotationally driven based on image data at a predetermined exposure position while scanning in the main scanning direction.
The image forming unit 3 fixes the toner image formed on the photoreceptors 11K, 11M, 11C, and 11Y to the paper P, and fixes the unfixed toner image on the paper P by the action of pressure or heating. A fixing device 50 as a fixing unit, a double-sided conveyance unit 32, and the like are provided.
The intermediate transfer unit 20 includes an intermediate transfer belt 21 that is stretched by a plurality of rollers 26, 27, and 28 and is rotationally driven in the direction of the arrow in the figure.
The intermediate transfer unit 20 sandwiches the intermediate transfer belt 21 between the photoreceptors 11K, 11M, 11C, and 11Y and the primary transfer rollers 23K, 23M, 23C, and 23Y to which a predetermined voltage is applied to form a primary transfer nip. .
In addition, the intermediate transfer unit 20 forms a secondary transfer nip by sandwiching the intermediate transfer belt 21 between the secondary transfer backup roller 26 and the secondary transfer roller 25 to which a predetermined voltage is applied.
Further, the intermediate transfer unit 20 includes a cleaning device 22 that removes transfer residual toner remaining on the intermediate transfer belt 21.
The toner images on the photoreceptors 11K, 11M, 11C, and 11Y formed by the process units 10K, 10M, 10C, and 10Y are sequentially superimposed and transferred onto the intermediate transfer belt 21 at the primary transfer nip.
The four-color superimposed toner images transferred onto the intermediate transfer belt 21 are collectively transferred onto the paper P at the secondary transfer nip.

The transfer residual toner remaining on the intermediate transfer belt 21 after passing through the secondary transfer nip is removed by the cleaning device 22.
Below the intermediate transfer unit 20 in the figure, there are a pair of registration rollers 44, a paper transfer unit 24 that moves endlessly between a secondary transfer roller 25 and a fixing device 50 by spanning an endless paper transfer belt. Yes.
The registration roller pair 44 sandwiches a sheet P supplied by a sheet feeding unit 4 described later between the rollers, and sends the sheet P to the secondary transfer nip at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 21.
The paper transport unit 24 transports the paper P on which the full-color image has been transferred through the secondary transfer nip to the fixing device 50.
The double-sided conveyance unit 32 located below the image forming unit 3 in the drawing reverses the paper P, which has undergone image fixing processing on one side, by switching the path of the paper P with a switching claw and enters the secondary transfer nip again. Let
Further, the paper feeding unit 4 of the copying machine includes a plurality of paper feeding cassettes 40 for storing a plurality of papers P in a bundle of paper sheets, and a paper feeding roller is provided on the uppermost paper P in each paper feeding cassette 40. 42 is pressed.

When the selected paper feed roller 42 is driven to rotate, the uppermost paper P is separated by the separation roller and sent out one by one toward the paper feed path 41.
The paper P sent out to the paper feed path 41 is guided to the paper feed path in the image forming unit 3 through a plurality of conveying roller pairs 43 and is sandwiched between the rollers of the registration roller pair 44.
In the image forming unit 3 configured as described above, image formation is performed as follows.
For example, in the black process unit 10K, the surface of the photoconductor 11K uniformly charged by the charging device 12K is irradiated with the laser beam modulated and deflected by the optical writing device 30 while being scanned, thereby causing an electrostatic latent image. Is formed.

The electrostatic latent image on the photoreceptor 11K is developed by the developing device 13K and becomes a black toner image.
The toner image on the photoreceptor 11K is transferred onto the paper P in the primary transfer nip that faces the primary transfer roller 23K with the intermediate transfer belt 21 interposed therebetween.
The surface of the photoconductor 11K after the toner image has been transferred is cleaned by the photoconductor cleaning device 14K to prepare for the formation of the next electrostatic latent image.
Also for the other process units 10M, 10C, and 10Y, the above-described image forming process is executed in synchronization with the movement of the intermediate transfer belt 21.

On the other hand, the paper P fed from the paper feed cassette 40 is sent out at a predetermined timing by the registration roller pair 44 and conveyed to the secondary transfer nip.
Alternatively, the paper P fed from the manual feed tray 45 installed on the side surface of the image forming unit 3 is fed out into the manual feed path by the feed roller and sent out at a predetermined timing by the registration roller 46 to be secondary. It is conveyed to the transfer nip.
Then, the paper P on which the full-color image is collectively transferred at the secondary transfer nip is transported by the paper transport unit 24 and the toner image is fixed by the fixing device 50.

In the single-sided print mode in which an image is formed only on the first surface of the paper P, the paper P sandwiched in the paper discharge nip between the rollers of the paper discharge roller pair 47 is directly discharged out of the apparatus and discharged into the paper discharge tray 48. Stacked on top.
In the double-sided print mode in which images are formed on both sides of the paper P, the paper P sandwiched between the paper discharge roller pair 47 is returned in the reverse direction and enters the double-sided conveyance unit 32.
After being turned upside down in the duplex conveying section 32, it is sent again to the secondary transfer nip and subjected to image secondary transfer processing and fixing processing on the other side. Discharged on 48.
After the toner image has been transferred, the residual toner is removed by the belt cleaning device 22 and the intermediate transfer belt 21 is ready for image formation by the process unit 10 again.
The paper transport unit 24, the secondary transfer roller 25, the paper feed roller 42, the transport roller pair 43, and the registration roller pair 44 constitute transport means.

  The above-described image forming operation is an operation when the full-color mode of four-color superposition is selected by the operation unit 101 described later. For example, when the monochrome image forming mode is selected on the operation unit 101, the support rollers other than the driving roller are moved to separate the photosensitive members 11K, 11M, 11C, and 11Y from the intermediate transfer belt 21, and the intermediate transfer Only the K toner image may be formed on the belt 21.

<Electrical configuration>
FIG. 7 is an example of a block diagram showing an electrical configuration of the image forming apparatus shown in FIG.
The image forming apparatus illustrated in FIG. 7 includes an ADF 1, a scanner unit 2, an image forming unit 3, an operation unit 101, a controller 102, and an HDD 103.
The operation unit 101 includes a power switch, a numeric keypad, a start key, a monitor, various setting keys, and a reset key.
The controller 102 includes condition setting means 104 configured by software in addition to a CPU, RAM, and ROM (not shown). The CPU is an abbreviation for Central Processing Unit, and controls the image forming apparatus as a whole. RAM is an abbreviation for Random Access Memory and temporarily stores data. ROM is an abbreviation for Read Only Memory and includes a control program. HDD is an abbreviation for Hard Disk Drive, and has a function of temporarily storing image data. However, a control program may be stored or operated as a RAM.
The condition setting means 104 for setting preheating conditions includes preheating selection means 105, temperature changing means 106, nip width changing means 107, linear velocity changing means 108, path changing means 109, and front / back condition changing means 110.

  The preheating selection means 105 is a means for selecting whether or not to preheat the paper. The temperature changing means 106 is means for changing the preheating temperature from a preset temperature to another temperature depending on the type / size of the paper. The nip width changing means 107 is a means for changing the nip width at the time of preheating from a preset nip width to another nip width depending on the type / size of the paper. The linear velocity changing means 108 is a means for changing the linear velocity at the time of preheating from a preset number of times to another number depending on the type / size of the paper. The route changing means 109 is a means for changing the conveyance path at the time of pre-heating the paper from a preset route to another line. Examples of the preset route include a switchback route and a double-sided conveyance route. The front / back condition changing means 110 is a means for changing the preheating conditions between the front side image formation for forming an image on the front side of the paper and the back side image formation for forming an image on the rear side of the paper.

Next, the conventional example and the operation of the present invention will be described.
<Operation 1 of Conventional Example>
FIG. 2 is an explanatory diagram of a conventional normal path (one side).
The paper fed from the paper feed roller 42 is transported in the order of the secondary transfer roller 25 → image transfer → paper transport unit 24 → fixing device 50 → discharge roller pair 47 as shown by the curved arrow A1. Are stacked on the paper discharge tray 48.

<Operation 2 of Conventional Example>
FIG. 3 is an explanatory diagram of a conventional normal path (both sides).
As indicated by the curved arrow A2, the paper fed from the paper feed roller 42 is transferred from the secondary transfer roller 25 → image transfer → paper transport unit 24 → fixing device 50 → double-side transport unit 32 → switchback path 49 → secondary. Transfer roller 25 → transfers the image. After the transfer, the paper is transported in the order of the paper transport unit 24 → the fixing device 50 → the discharge roller pair 47, and finally stacked on the discharge tray 48.

<Operation 1>
FIG. 4 is an explanatory diagram of the preheating (switchback path) of the present invention.
As shown by the curved arrow A3, the paper fed from the paper feed roller 42 is the secondary transfer roller 25 → no image is transferred → the paper transport unit 24 → the fixing device 50 → heated to expand / contract the paper → double-side transport unit The sheet is conveyed in the order of 32 → switchback path 49 → secondary transfer roller 25. Further, the sheet is transported in the order of image transfer → paper transport unit 24 → fixing device 50 → discharge roller pair 47, and finally stacked on the discharge tray 48.

<Operation 2>
FIG. 5 is an explanatory view of the preheating (double-sided conveyance path) of the present invention.
As indicated by the curved arrow A4, the paper fed from the paper feed roller 42 is shrunk by the secondary transfer roller 25 → no image transfer → paper transport unit 24 → fixing device 50 → heat. After paper shrinkage, double-sided conveyance unit 32 → does not enter switchback path 49 → secondary transfer roller 25 → image transfer → paper conveyance unit 24 → fixing device 50 → paper discharge roller pair 47, and finally Are stacked on the discharge tray 48.

<Operation 3>
FIG. 6 is a flowchart of the overall operation.
After receiving the job, it is determined whether or not preheating is performed (step S1).
When preheating is performed (step S1 / Y), the preheating setting conditions shown in steps S2 to S13 are set, and when preheating is not performed (step S1 / N), printing is performed (step S15).
That is, it is determined whether or not to change the temperature (step S2). When the temperature is changed (step S2 / Y), the temperature setting is changed and the process proceeds to step S4 (step S3). When the temperature is not changed (step S2) / N), proceed to step S4.
In step S4, it is determined whether or not the number of times is changed. When changing the number of times (step S4 / Y), the number of times setting is changed and the process proceeds to step S6. For example, for thin paper or B5 size, it may be set once, and for thick paper or A3 size, it may be set twice (step S5). When the number of times is not changed (step S4 / N), the process proceeds to step S6. move on.
In step S6, it is determined whether or not to change the nip width. When changing the nip width (step S6 / Y), change the nip width setting and proceed to step S8 (step S7). When not changing the nip width setting (step S6 / N), proceed directly to step S8.
In step S8, it is determined whether or not to change the linear velocity. When changing the linear velocity (step S8 / Y), change the linear velocity setting and proceed to step S10 (step S9). When not changing the linear velocity (step S8 / N), proceed directly to step S10.
In step S10, it is determined whether or not to change the track. When the line is changed (step S10 / Y), the line setting is changed and the process proceeds to step S12 (step S11). When the line is not changed (step S10 / N), the process proceeds to step S12 as it is.
In step S12, it is determined whether to change the front / back conditions. When changing the front / back condition (step S12 / Y), change the front / back condition setting and proceed to step S14 (step S13). When not changing the front / back condition (step S12 / N), proceed directly to step S14.
In step S14, preheating is performed, and printing is performed after the preheating is performed (step S15).
That is, the preheating setting condition is determined by selecting an item that the user wants to implement.

<Program>
The image forming apparatus according to the present invention described above is realized by a program that causes a computer to execute processing. Examples of the computer include general-purpose computers such as personal computers and workstations, but the present invention is not limited to this. Therefore, as an example, a case where the function of the present invention is realized by a program will be described below.

For example, a fixing unit, conveying means for passing a paper on which a toner image has been formed after paper before image formation is passed through the fixing unit and preheating, and conditions for preheating the paper In the computer of the image forming apparatus provided with pre-heating selection means, temperature change means, frequency change means, nip width change means, linear speed change means, path change means, and front / back condition change means as condition setting means for setting
A procedure for the preheating selection means to select whether or not to preheat the paper;
A procedure in which the temperature changing means changes the preheating temperature from the set temperature according to the type / size of the paper;
A procedure in which the number of times changing means changes the number of times of preheating from the set number of times according to the type / size of paper
A procedure for the nip width changing means to change the nip width at the time of preheating from the set nip width depending on the type / size of the paper,
A procedure in which the linear velocity changing means changes the linear velocity during preheating from the set number of times according to the type / size of the paper;
A procedure in which the path changing means changes the conveyance path at the time of the pre-heating of the paper from the set path;
A procedure in which the front and back condition changing means changes the preheating conditions between the front side image forming image on the front side of the paper and the back side image forming forming the image on the back side of the paper,
A computer-readable program for executing

  Such a program may be stored in a computer-readable storage medium.

<Storage medium>
Here, examples of the storage medium include computer-readable storage media such as CD-ROM, flexible disk (FD), and CD-R, semiconductor memories such as flash memory, RAM, ROM, and FeRAM, and HDD.

  CD-ROM is an abbreviation for Compact Disc Read Only Memory. Flexible disk means Flexible Disk (FD). CD-R is an abbreviation for CD Recordable. FeRAM is an abbreviation for Ferroelectric RAM and means a ferroelectric memory.

<Effect>
As described above, the paper contracts by heating the paper before printing. By printing on the paper after shrinkage, the shrinkage amount of the paper can be minimized. As a result, high quality printing is possible. In other words, by preheating the paper before printing, it is possible to improve the image quality by printing in a state in which the shrinkage of the paper due to heat is reduced. It can be fixed.

Being able to set the preheating conditions finely improves productivity, and improves image quality and energy savings.
-Productivity For paper with a high shrinkage rate, increasing the preheating temperature setting can promote shrinkage and improve productivity.
・ High image quality If the paper cannot be fully shrunk, it will shrink when fixing the image, so it will not be possible to completely remove the unevenness of the image, but the preheating conditions can be set in detail, so that the setting conditions suitable for the paper Can be provided.
・ Energy saving By setting a preheating temperature suitable for shrinking paper, it is possible to expect high image quality without excessive heat.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there. In the above-described embodiment, the case where only preheating is performed on the paper has been described. However, the present invention is not limited to this, and it may be configured to apply pressure when preheating the paper with the fixing unit. . That is, the paper expands and contracts by heating and pressurizing the paper with the fixing unit before printing. By printing on the paper after expansion / contraction, the expansion / contraction amount of the paper, that is, the deformation amount can be minimized. As a result, high quality printing is possible.

1 ADF
2 Scanner unit 3 Image forming unit 4 Paper feeding unit 11K, 11M, 11C, 11Y Photoconductor 12K, 12M, 12C, 12Y Charging device 13K, 13M, 13C, 13Y Developing device 14K, 14M, 14C, 14Y Photoconductor cleaning device 20 Intermediate transfer unit 21 Intermediate transfer belt 25 Secondary transfer roller 30 Optical writing device 50 Fixing device (fixing unit)
DESCRIPTION OF SYMBOLS 101 Operation part 102 Controller 104 Condition setting means 105 Preheating selection means 106 Temperature change means 107 Nip width change means 108 Linear speed change means 109 Line change means 110 Front / back condition change means

JP 2012-108461 A

Claims (10)

A fixing unit;
Conveying means for passing a sheet on which a toner image is formed after the sheet before image formation is passed through the fixing unit and pre-heated to the fixing unit;
An image forming apparatus comprising: condition setting means for setting conditions for preheating the paper.   The image forming apparatus according to claim 1, wherein the condition setting unit includes a preheating selection unit that selects whether or not the preheating is performed on the sheet.   The image forming apparatus according to claim 1, wherein the condition setting unit includes a temperature changing unit that changes a temperature of the preheating from a set temperature according to a type / size of the paper.   4. The image forming apparatus according to claim 1, wherein the condition setting unit includes a number of times changing unit that changes the number of times of the preheating from the set number of times according to the type / size of the paper. 5.   5. The condition setting unit includes a nip width changing unit that changes a nip width at the time of the preheating from a set nip width depending on a type / size of the paper. Image forming apparatus.   6. The condition setting means includes linear speed changing means for changing a linear speed during the preheating from a set number of times according to the type / size of the paper. Image forming apparatus.   7. The image forming apparatus according to claim 1, wherein the condition setting unit includes a path changing unit that changes a conveyance path at the time of the pre-heating of the paper from a set path. .   The condition setting means includes front and back condition changing means for changing the preheating condition between the front side image formation for forming an image on the front side of the paper and the back side image formation for forming an image on the rear side of the paper. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   Whether or not to pre-heat the paper before image formation through the fixing unit, in the case of the pre-heating, the temperature, the number of times, the nip width, the linear velocity, the path, the front and back conditions are selected and pre-heated An image forming method comprising: forming a toner image later; and passing the paper on which the toner image is formed again through the fixing unit. Sets the fixing unit, the transport means for passing the paper on which the toner image has been formed after the paper before image formation is passed through the fixing unit and preheated, and the conditions for preheating the paper. A computer of an image forming apparatus provided with preheating selection means, temperature change means, frequency change means, nip width change means, linear velocity change means, path change means, and front / back condition change means as condition setting means to
A procedure for the preheating selection means to select whether or not to preheat the paper;
A procedure in which the temperature changing means changes the preheating temperature from a set temperature according to the type / size of the paper;
A procedure in which the number-of-times changing means changes the number of times of preheating from a set number of times according to the type / size of paper;
A procedure in which the nip width changing means changes the nip width at the time of preheating from the set nip width depending on the type / size of the paper;
A procedure in which the linear velocity changing means changes the linear velocity at the time of preheating from a set number of times depending on the type / size of the paper;
A procedure in which the path changing unit changes a conveyance path at the time of the pre-heating of the paper from a set path;
The front and back condition changing means is a procedure for changing the preheating conditions between the front side image forming image on the front side of the paper and the back side image forming forming the image on the back side of the paper,
A computer-readable program for executing the program.

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