JP2008275938A - Image forming apparatus and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce down time for a user by shortening time required for formation of various toner patterns. <P>SOLUTION: The transfer unit 11 of an electrophotographic image forming apparatus transfers a predetermined toner pattern, used for a color shift correction, toner concentration correction, displacement correction, or the like, onto transfer paper 2 and/or a transfer belt 3, so as to form an image. When the transfer unit 11 forms an image by transferring a predetermined toner pattern to the transfer belt 3, control is performed so that the speed of image formation is higher than the speed of image formation made by transferring to the transfer paper 2. In other words, the speed of toner pattern image formation not accompanied with printing on paper is made higher than the speed of image formation accompanied with printing on paper. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a laser printer, a digital copying machine, and a facsimile apparatus, and a control method therefor.

  Image forming apparatuses including laser printers, digital copiers, and the like perform various correction controls and cleaning controls even during printing operations that form images on paper. However, for the user, all the time taken for control other than paper printing is downtime, and it is necessary to shorten this downtime.

Therefore, in the prior art, during execution of control that does not affect image formation, it has been proposed that the control speed be higher than the normal speed. For example, in Patent Document 1 and Patent Document 2, downtime is shortened by making the speed of the conveyor belt faster than the speed of the conveyor belt at the time of toner pattern imaging during control that does not affect image formation such as cleaning of the conveyor belt. Techniques to do this have been proposed.
JP 2006-146066 A JP 2006-053594 A

  However, it is desirable to shorten the time required to form various correction toner patterns because it is one of the main factors that cause downtime.

  Therefore, in view of the above circumstances, the present invention provides an image forming apparatus that forms a predetermined toner pattern with an image forming speed at the time of toner pattern image formation without paper printing higher than that at the time of paper print image formation. The purpose is to shorten the time required for image formation of various toner patterns by reducing the speed and to reduce the downtime for the user.

  In order to achieve the above object, the invention according to claim 1 is a photoconductor, a charging unit for charging the surface of the photoconductor, an exposure unit for projecting light according to image information onto the photoconductor, and the photoconductor. Development means for forming a toner image thereon, and transfer means for transferring a visible image of the photosensitive member to at least one of the intermediate transfer member and the transfer paper, the transfer means transferring a predetermined toner pattern When an image is formed and the transfer unit transfers the predetermined toner pattern to the intermediate transfer member to form an image, the image forming speed is faster than the image forming speed when the image is formed by transferring to the transfer paper. An image forming apparatus characterized by performing control to perform the above.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the exposure unit includes a light source unit, a light source lighting control unit that controls lighting of the light source unit according to image information, and an output from the light source unit. A light beam deflection control means for controlling the deflection of the light beam to be deflected, and a scanning imaging optical system for scanning and imaging the light beam deflected by the light beam deflection control means. When the transfer unit transfers the predetermined toner pattern to the intermediate transfer body to form an image, the control speed is the same as the control speed when the transfer unit transfers the image to the transfer paper to form an image. .

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, when the transfer unit transfers the predetermined toner pattern to the intermediate transfer member to form an image, the image forming apparatus is turned on. When the cover is closed after the cover of the image forming apparatus cover is closed, during the operation for preparing the image formation on the transfer paper, and when the image is continuously formed on the transfer paper, It is characterized in that there are at least one of them.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, when the transfer unit transfers the predetermined toner pattern to the intermediate transfer body to form an image, the light source light quantity At least one of the charging bias and the transfer bias is changed from that in the case of forming an image by transferring to the transfer paper.

  According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the fourth aspect, wherein the transfer unit forms an image of the predetermined toner pattern with respect to the light source light amount, the charging bias, and the transfer bias. The image forming conditions are stored, and the image formation is performed by switching the light source light amount, the charging bias, and the transfer bias according to the image forming conditions.

  A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, wherein the predetermined toner pattern is an image density detection toner pattern.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the predetermined toner pattern is a color misregistration correction toner pattern.

  According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the exposure unit includes a light beam diameter adjusting unit that adjusts a diaphragm of the light beam diameter, and the transfer unit includes the predetermined transfer unit. When the toner pattern is transferred to the intermediate transfer member to form an image, the beam diameter is increased.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, the predetermined toner pattern includes a reference portion including a straight line extending in parallel with the main scanning direction and a hatched portion including a straight line extending obliquely. And a pattern generating means for generating the predetermined toner pattern by varying an angle formed by the straight line of the reference portion and the straight line of the shaded portion.

According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the pattern generation unit is configured such that the transfer unit forms an image by transferring the predetermined toner pattern onto the transfer sheet. The image forming speed is increased by N times, and when the predetermined toner pattern is transferred to the intermediate transfer member to form an image, the predetermined toner pattern is represented by the straight line of the reference portion and the straight line of the hatched portion. The angle D formed by
D [degree] = Tan ^ -1 (1 / N) * 180 ° / π
(Where Tan ^ -1 is the arctangent)
It is characterized by producing | generating as.

  In the invention according to claim 11, when the transfer means transfers a predetermined toner pattern to the intermediate transfer member to form an image, the image forming speed is higher than the image forming speed when the image is formed by transferring to a transfer paper. And a control method for the image forming apparatus.

  According to the present invention, it is possible to reduce the time required for image formation of various toner patterns and to reduce the downtime for the user.

An embodiment of the present invention will be described by taking a tandem type color image forming apparatus as an example.
FIG. 1 shows an exposure unit, an image processing unit, and a transfer unit of a color image forming apparatus.

  An image processing unit 1 for forming a multi-color toner image (note that the configuration around the image processing units 1b, 1c, and 1d is the same as that of the image processing unit 1a and is omitted in FIG. 1) as a transfer medium. Are arranged in a line along a transfer belt 3 that conveys the transfer paper 2. The transfer belt 3 is rotationally driven in the direction of the arrow in FIG. 1 by the rotation of a driving roller that rotates. Below the transfer belt 3, a paper feed tray 2 ′ in which transfer paper 2 is stored is provided. The transfer paper 2 stored in the paper feed tray 2 ′ is fed toward the transfer belt 3 at the time of paper print image formation, and is conveyed to the image processing unit 1, where paper print image formation is performed.

  The exposure unit 4 includes a deflector including a polygon motor 5 and a polygon mirror (rotating member) 6 for deflecting light beams emitted from a plurality of semiconductor lasers serving as light sources. Further, the exposure unit 4 includes a scanning lens (fθ lens) 7 serving as a scanning optical system that uses a plurality of light beams deflected by the deflector as scanning lines, respectively, via an imaging optical system. The plurality of scanning lines enter the image processing unit 1 through an optical system including a mirror and the like.

  The image processing unit 1 includes a photosensitive drum 8, a charger 9 and a developing device 10 arranged around the photosensitive drum 8. The surface of the photosensitive drum 8 is uniformly charged by the charger 9 and then exposed to a laser beam corresponding to the image from the exposure unit 4 to form an electrostatic latent image. The formed electrostatic latent image is developed by the developing device 10 to form a toner image on the photosensitive drum 8. The toner image is transferred to the transfer paper 2 by the transfer device 11 at a position (transfer position) where the photosensitive drum 8 and the transfer paper 2 on the transfer belt 3 are in contact with each other, thereby forming an image on the transfer paper 2. Is done.

  The transfer paper 2 transferred by the image processing unit 1a is conveyed by the transfer belt 3 to the next image processing unit 1b. Similarly, the individual toner images formed on the photosensitive drum 8 are transferred onto the transfer paper 2 in an overlapping manner. The transfer paper 2 is further conveyed to the third and fourth image processing units 1c and 1d in order, and similarly, the formed toner image is transferred to the transfer paper 2 so that a color image is formed on the transfer paper 2. It will form. Then, the transfer paper 2 on which the color image is formed is peeled off from the transfer belt 3, fixed by the fixing device 12, and then discharged.

  Next, the color misregistration correction pattern 13 formed on the transfer belt 3 will be described with reference to FIG. FIG. 2 is a side view and a top view of the transfer belt 3 on which the color misregistration correction pattern 13 is formed.

  The toner image pattern for color misregistration detection is also formed on the transfer belt 3 in the same manner as the toner image at the time of forming the paper print image. In this embodiment, as shown in FIG. 2, a color misregistration detection toner image pattern is formed in an area A that is outside the area of the transfer paper 2. With the conveying speed V of the transfer belt 3, the area A sequentially passes the position of each color photosensitive drum 8. A toner image pattern for color misregistration detection is formed in accordance with the passing timing. The formed color misregistration correction pattern (color misregistration detection / correction toner pattern) 13 is detected by a detection sensor 14 for detection. Therefore, in the present embodiment, the detection sensor 14 is disposed on the transfer belt 3, and the color misregistration correction pattern 13 is formed on the transfer belt 3 in accordance with the position where the detection sensor 14 is disposed. Such a color misregistration correction pattern 13 is detected when the transfer belt 3 rolls and sequentially passes through the detection sensor 14.

  The time required for the color misregistration correction (detection) is “downtime of the apparatus” for the user. Therefore, it is necessary to shorten the time for forming and detecting a toner image pattern for color misregistration detection relating to color misregistration correction.

Therefore, a method for shortening the formation time of the toner pattern and detection will be described below.
In the following embodiment, it has been shown that the “downtime of the apparatus” is shortened by increasing the conveyance speed V on the transfer belt 3 when forming a toner pattern for color misregistration detection. The pattern is not limited to the toner pattern for detection, and may be a toner density correction pattern or a positional deviation correction pattern.

  FIG. 3 is a diagram showing the time when two printing operations are performed when the conveyance speed V on the transfer belt 3 is constant. FIG. 4 shows the conveyance speed V on the transfer belt 3. It is a figure which shows time when the printing operation of 2 sheets was performed when speeds other than paper printing were made twice the speed at the time of paper printing. By setting the speed other than paper printing to twice the speed at the time of paper printing, the correction operation period before printing is shortened, and the “apparatus downtime” is shortened. Although the time required for printing two sheets of paper is the same, the time other than paper printing is shortened and t1> t2, so that the total time required for printing can be shortened.

  However, if the light emission energy per unit time is constant regardless of the conveyance speed V on the transfer belt 3 as indicated by E0 in FIG. 5, there is a possibility that the toner density is lowered during high-speed image formation. FIG. 5 is a diagram showing the relationship between V and the light emission energy E of the light source means of the exposure unit 4 when the conveyance speed V on the transfer belt 3 is changed.

  When an image is formed with the conveyance speed V on the transfer belt 3 being N times, the rotational speed of the photosensitive drum 8 is also N times due to the configuration of the image processing unit 1. When the rotational speed of the photosensitive drum 8 is set to N times, the time for irradiating the unit area of the photosensitive drum 8 is shortened, the exposure energy is reduced, and as a result, the toner image density is lowered. Therefore, in order to prevent the toner image density from decreasing, the light emission energy E of the light source means of the exposure unit 4 is increased. As shown in FIG. 5E, by controlling the light emission energy E in proportion to the conveying speed V on the transfer belt 3, the photosensitive drum 8 can always obtain a constant exposure energy, and the toner image density can be reduced. Can be kept constant.

  In this embodiment, the method of increasing the light emission energy E of the light source means of the exposure unit 4 is shown in order to prevent the decrease in the toner image density. However, a method of adjusting the charging bias / transfer bias may be used. Further, a means for storing the light emission energy E of the light source means necessary for obtaining a constant toner density with respect to the conveyance speed V on the transfer belt 3 is provided, and is switched according to the conveyance speed V on the transfer belt 3. It is good also as a structure.

  Further, when an image is formed by changing the conveying speed V on the transfer belt 3, the image is deformed unless the control speed of the light source lighting control means and the light beam deflection control means of the optical unit is also changed. For example, when the control speed of the light source lighting control means and the light beam deflection control means of the optical unit is kept as it is and the transport speed V on the transfer belt 3 is doubled, the image formed is sub-scanned as shown in FIG. It will double in the direction. Further, when the conveyance speed V on the transfer belt 3 is doubled, a line that is not exposed is generated for each main scanning line, and a gap is generated in the toner image. An example in the case where an unexposed line is generated is shown in the upper part of FIG.

  However, there is a restriction that the operable range of the light beam deflecting means cannot be changed narrowly, and the control speed of the light source lighting control means and the light beam deflection control means of the optical unit may not be changed together. Need to be resolved.

Referring to FIG. 7, there is shown a configuration in which the optical unit is provided with a light beam diameter adjusting means for adjusting the aperture of the light beam diameter.
In FIG. 7, in order to change the focal distance to the photosensitive drum 8, a distance adjusting means 16 for the optical system is provided. By moving the distance adjusting means 16 in the direction of the arrow in FIG. 7, the focal length is changed and the diameter of the light beam is changed. When the conveyance speed V on the transfer belt 3 is increased, the gap between the main scanning lines can be eliminated as shown in the lower part of FIG. 8 by changing the beam diameter.

  Further, as shown in FIG. 6, when the color misregistration correction pattern extends in the sub-scanning direction, the angle formed by the reference portion that is a straight line extending in the main scanning direction and the oblique line portion that extends obliquely changes. However, if the angle formed by the reference portion and the shaded portion is 45 degrees, for example, it is easy to derive the main scanning deviation amount from the sub-scan passage timing.

Therefore, when an image is formed with the conveyance speed V on the transfer belt 3 multiplied by N, an angle D formed by the reference portion and the shaded portion of the color misregistration correction toner pattern is expressed as follows:
D [degree] = Tan ^ -1 (1 / N) * 180 ° / π
(However, Tan ^ -1: Arc tangent)
As a result of the pattern generation, the angle formed between the reference portion and the shaded portion on the transfer belt 3 can always be 45 degrees. For this reason, it is possible to make it easy to calculate the color misregistration correction amount. In addition, what is necessary is just to take methods, such as changing the inclination of a shaded part, in order to change the angle made. The toner pattern is generated by software processing using an image processing controller (not shown) of the image forming apparatus.

  According to the present embodiment described above, in the image forming apparatus that forms a predetermined toner pattern, the image forming speed at the time of toner pattern image formation without paper printing is set to the image forming time at the time of paper print image formation. Therefore, it is possible to reduce the time required for image formation of various toner patterns and to reduce the downtime for the user.

  Further, according to the present embodiment, at the time of toner pattern imaging without paper printing, any one or more of the light source light amount, charging bias, and transfer bias is changed from the time of paper printing imaging. Therefore, it is possible to prevent a decrease in toner density during high-speed image formation.

  In addition, since the optical unit is provided with a light beam diameter adjusting means for adjusting the aperture of the light beam diameter, and the toner pattern is formed without paper printing, the light beam diameter is increased. It is possible to eliminate the gap between the main scanning lines by changing the beam diameter when the speed is increased.

Further, as shown in FIG. 6, when the color misregistration pattern extends in the sub-scanning direction, the angle formed by the reference portion that is a straight line extending in the main scanning direction and the hatched portion that is a diagonally extending straight line changes. . However, if the angle formed by the reference portion and the hatched portion is 45 °, the main scanning deviation amount can be easily derived from the sub-scan passage timing. Therefore, when an image is formed with the conveyance speed V on the transfer belt 3 multiplied by N, an angle D formed by the reference portion and the shaded portion of the color misregistration correction toner pattern
D [degree] = Tan ^ -1 (1 / N) * 180 ° / π
(However, Tan ^ -1: Arc tangent)
As a result of the pattern generation, the angle formed by the reference portion and the shaded portion on the transfer belt 3 can always be 45 °. For this reason, it is possible to make it easy to calculate the color misregistration correction amount.

  In addition, the color misregistration correction toner pattern formed on the photosensitive member and / or the intermediate transfer member includes at least one set of a reference portion formed of a straight line extending in the main scanning direction and a hatched portion formed of a straight line extending obliquely. Since the angle formed between the reference portion and the hatched portion is variable, it is possible to make it easy to calculate the color misregistration correction amount even when the image forming speed is faster than that for paper printing. .

It is a figure which shows the principal part of the color image forming apparatus of embodiment by this invention. FIG. 4 is a side view and a top view of the transfer belt 3 on which a color misregistration correction pattern 13 is formed. FIG. 10 is a diagram illustrating time when two printing operations are performed when the conveyance speed V on the transfer belt 3 is constant. It is a figure which shows the time when the printing operation of 2 sheets is performed about the conveyance speed V on the transfer belt 3, when speeds other than paper printing are doubled at the time of paper printing. FIG. 6 is a diagram illustrating a relationship between V and light emission energy E of a light source unit of an exposure unit 4 when a conveyance speed V on the transfer belt 3 is changed. FIG. 10 is a diagram for explaining that a color misregistration correction pattern extends in the sub-scanning direction when the conveyance speed V is increased. It is a figure which shows an example of the structure provided with the light beam diameter adjustment means which adjusts the aperture_diaphragm | restriction of a light beam diameter in the optical part of this embodiment. FIG. 4 is a diagram illustrating an example of a toner image when the conveyance speed V on the transfer belt 3 is doubled, and in particular, the lower part is a diagram illustrating an example of a configuration including a light beam diameter adjusting unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image process part 2 Transfer paper 2 'Paper feed tray 3 Transfer belt 4 Exposure part 5 Polygon motor 6 Polygon mirror 7 Scan lens 8 Photosensitive drum 9 Charging device 10 Developing device 11 Transfer device 12 Fixing device 13 Color misregistration correction pattern 14 Detection Sensor 16 Distance adjustment means

Claims (11)

A photosensitive member; a charging unit that charges the surface of the photosensitive member; an exposure unit that projects light according to image information onto the photosensitive member; a developing unit that forms a toner image on the photosensitive member; an intermediate transfer member; Transfer means for transferring a visible image of the photoreceptor to at least one of transfer paper,
The transfer means transfers a predetermined toner pattern to form an image,
When the transfer unit transfers the predetermined toner pattern to the intermediate transfer member to form an image, control is performed so that the image forming speed is higher than the image forming speed when the image is formed by transferring to the transfer paper. An image forming apparatus. The exposure means includes
Light source means, light source lighting control means for controlling lighting of the light source means according to image information, light beam deflection control means for controlling deflection of a light beam output from the light source means, and light beam deflected by the light beam deflection control means A scanning imaging optical system for scanning and imaging,
The control speed of the light source lighting control means and the light flux deflection control means is:
2. The control speed when the transfer unit transfers the predetermined toner pattern to the intermediate transfer member to form an image, and is the same as a control speed when transferring the image onto the transfer paper to form an image. Image forming apparatus. When the transfer unit transfers the predetermined toner pattern to the intermediate transfer member to form an image,
When the image forming device is turned on,
When the cover is closed after the cover of the image forming device cover is open,
During operation to prepare image formation on transfer paper,
The image forming apparatus according to claim 1, wherein the image forming apparatus is at least one of a transfer sheet and a transfer sheet when images are continuously formed on the transfer sheet. When the transfer unit transfers the predetermined toner pattern to the intermediate transfer body to form an image,
4. The apparatus according to claim 1, wherein at least one of a light source light amount, a charging bias, and a transfer bias is changed from that used when an image is formed on the transfer paper. The image forming apparatus according to Item. A means for storing image forming conditions for all cases where the transfer unit forms an image of the predetermined toner pattern with respect to the light source light amount, the charging bias, and the transfer bias;
The image forming apparatus according to claim 4, wherein an image is formed by switching the light source light amount, the charging bias, and the transfer bias according to the image forming conditions.   6. The image forming apparatus according to claim 1, wherein the predetermined toner pattern is an image density detection toner pattern.   The image forming apparatus according to claim 1, wherein the predetermined toner pattern is a color misregistration correction toner pattern. The exposure means includes a light beam diameter adjusting means for adjusting a diaphragm of the light beam diameter,
8. The image forming apparatus according to claim 7, wherein the light beam diameter adjusting means increases the light beam diameter when the transfer means transfers the predetermined toner pattern to the intermediate transfer member to form an image. The predetermined toner pattern is:
It is composed of at least one set including a reference portion made of a straight line extending in parallel to the main scanning direction and a shaded portion made of a straight line extending obliquely,
9. The image forming apparatus according to claim 7, further comprising a pattern generation unit configured to generate the predetermined toner pattern by changing an angle formed by the straight line of the reference portion and the straight line of the shaded portion. The pattern generation means includes
The transfer means transfers the predetermined toner pattern to the intermediate transfer member by increasing the image forming speed N times faster than the image forming speed when the predetermined toner pattern is transferred to the transfer paper to form an image. The predetermined toner pattern when forming an image by
The angle D formed by the straight line of the reference part and the straight line of the shaded part is:
D [degree] = Tan ^ -1 (1 / N) * 180 ° / π
(Where Tan ^ -1 is the arctangent)
The image forming apparatus according to claim 9, wherein:   Image forming characterized in that when the transfer means transfers a predetermined toner pattern to an intermediate transfer member to form an image, the image forming speed is higher than the image forming speed when the image is formed by transferring to a transfer paper. Control method of the device.

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