JP2005241844A - Color image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming device capable of efficiently forming toner patterns of each color for adjustment of image forming conditions in short time and forming the toner patterns by reducing intervals of the adjacent toner patterns. <P>SOLUTION: The color image forming device alternately forms the toner patterns PY1 to PY4, PC1 to PC4 for adjusting the image forming conditions about toner of at least two colors, for example, such as PY1, PC1, PY2, PC2, PY3 ... on an intermediate transfer object 8 in its surface travel direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic color image forming apparatus that uses a plurality of toners of different colors and forms an image using an intermediate transfer member.

  In an image forming apparatus using electrophotographic technology, an image carrier such as a photoconductor, toner used, and peripheral devices are sometimes affected by fatigue, changes with time, changes in ambient temperature and humidity, etc. Concentration changes.

  Therefore, in order to stabilize the image density with good reproducibility, image formation such as the charging potential of the image carrier by the charging device, the developing bias potential, the peripheral speed ratio between the image carrier and the developing roller, the exposure amount of the image exposure device, etc. Various techniques for controlling conditions have been proposed.

  When an electrophotographic color image forming apparatus that uses a plurality of toners having different colors and forms an image using an intermediate transfer member, a plurality of image densities on the intermediate transfer member for each color toner subject to image formation condition adjustment are described. Toner images of different colors are formed, and the image forming conditions are adjusted based on the result of measuring the density of the toner pattern, so that a toner image of each color is formed with an appropriate image density, and the final output image It is done to improve the quality.

  For example, Japanese Patent Laid-Open No. 2001-350300 discloses an electrophotographic color image forming apparatus that uses a plurality of toners having different colors and forms an image using an intermediate transfer member. The density of the toner pattern (patch image) on the intermediate transfer member formed by changing the density is detected by the detection means, and the optimum development bias potential is set so as to obtain the desired image density based on the detection result, and the image density Is disclosed.

  Regarding the formation of such a toner pattern, conventionally, among a plurality of color toners subject to image formation condition adjustment, first, a plurality of toner patterns having different image densities are formed on the intermediate transfer member for any one color toner. Subsequently, a plurality of toner patterns are sequentially formed for each color toner, such as a plurality of toner patterns having different image densities are formed on the intermediate transfer member for the next color toner. The toner pattern formation described in JP-A-2001-350300 is also based on this procedure.

FIG. 5 shows a conventional example of such toner pattern formation.
In the toner pattern formation shown in FIG. 5, four toner patterns (patch images) PY1, in which the density of the yellow toner is sequentially reduced on the intermediate transfer member by switching the charging potential of the image carrier in the image forming apparatus, After the formation of PY2, PY3, and PY4, four toner patterns (patch images) PC1, PC2, PC3, and PC4 are formed in which the density of the cyan toner is gradually decreased.

JP 2001-350300 A

  However, when forming a plurality of patterns having different image densities for one color toner, after the first pattern is formed, when the image forming conditions are switched to form the second pattern, for example, image formation is performed. It takes time for switching image forming conditions such as switching time of high-voltage power output to a charging device for charging an image carrier such as a photosensitive member in the apparatus, stabilization time of the surface potential of the photosensitive member, etc. The same applies to the formation of the fourth and fourth patterns.

  As shown in FIG. 6, a conventional example of pattern formation shown in FIG. 5 has a yellow toner pattern group and a cyan toner pattern group due to a waiting time between adjacent patterns (here, a time required for charging potential switching). The time required for formation becomes longer. Further, since the interval between the formed adjacent toner patterns is large, it takes much time to detect the image density of the toner patterns.

  As described above, it takes a considerable time to form a plurality of toner patterns for each of a plurality of color toners, and the interval between the formed adjacent toner patterns is large. Therefore, when viewed as the entire image forming apparatus, it takes a long time to adjust the image forming conditions until the original image formation can be started, and the image forming apparatus is difficult to use.

  In addition, when the system speed of the image forming apparatus is increased, the toner pattern forming interval for switching the image forming condition becomes larger, and as a result, the image forming condition is similarly increased regardless of the increase in the system speed. Adjustment time becomes longer.

  Accordingly, the present invention can form an image using an intermediate transfer member using a plurality of toners having different colors, and form a plurality of toner patterns having different image densities on the intermediate transfer member for each color toner subject to image formation condition adjustment. An electrophotographic color image forming apparatus that adjusts the image forming conditions based on the result of measuring the density of the toner pattern, and can efficiently form the toner patterns for adjusting the image forming conditions in a short time. In addition, a color image forming apparatus is provided that can be formed with a small interval between adjacent toner patterns so that toner pattern density detection can be performed in a short time, and thus can reduce the waiting time for adjusting image forming conditions. This is the issue.

  In order to solve the above-described problems, the present invention can form an image using a plurality of toners having different colors and an intermediate transfer member, and a plurality of image density of each color toner subject to image formation condition adjustment on the intermediate transfer member. An electrophotographic color image forming apparatus that forms different toner patterns and adjusts image forming conditions based on the result of measuring the density of the toner patterns, wherein the toner patterns for at least two colors of toner are Provided is a color image forming apparatus which alternately forms in the surface traveling direction of an intermediate transfer member.

  According to the color image forming apparatus of the present invention, the toner patterns for at least two colors of toner for adjusting the image forming conditions are alternately formed in the surface traveling direction of the intermediate transfer member. After forming the first pattern among a plurality of toner patterns for one color toner, the time required to switch and stabilize the image forming conditions to form the second pattern, that is, the second pattern While the pattern is not yet ready to be formed, the first toner pattern for the other color toner can be formed, and after the first pattern of the other color toner is formed, the second pattern of the other color toner is not yet formed. The second pattern of the toner of one color can be formed while it is not in a state where the toner can be formed.

In this way, a toner pattern of another color can be formed during the waiting time until the next pattern formation can be started with the same color toner after one pattern is formed. It can be formed efficiently in a short time, and as a result, the waiting time for adjusting the image forming conditions can be shortened accordingly.
Further, since the interval between adjacent toner patterns to be formed becomes shorter, the toner pattern image density can be detected in a shorter time.

  The color image forming apparatus according to the present invention may employ four color toners (typically cyan, magenta, yellow, and black) as the plurality of color toners. In this case, the color image forming apparatus can form a full color image.

  In this way, in a color image forming apparatus employing four color toners, in order to efficiently form a toner pattern for adjusting the image forming conditions, the toner pattern for each of the four color toners is transferred to the intermediate transfer member. The two color toners may be divided into two in the width direction, and the two color toners may be alternately formed in the progress direction of the surface of the intermediate transfer member.

In any case, multiple toner patterns of the same color
(1) When forming by switching the charging potential of the image carrier in the image forming apparatus used for the toner pattern formation,
(2) When forming by switching the developing bias potential of the developing device in the image forming apparatus used for the toner pattern formation,
(3) The case of forming by switching the exposure amount of the image exposure apparatus in the image forming apparatus used for the toner pattern formation can be exemplified.
In addition to the above, a plurality of toner patterns can also be formed by switching the peripheral speed ratio between the image carrier and the developing roller in the image forming apparatus used for toner pattern formation.

As a color image forming apparatus according to the present invention,
(1) An electrostatic latent image carrier such as a photosensitive drum, and an image forming unit including a charging device, an image exposure device, and a developing device facing the electrostatic latent image carrier are prepared for each of a plurality of color toners. The toner image is arranged along the intermediate transfer member, and a toner image is formed with the toner of the color used in each image forming unit and transferred to the intermediate transfer member, so that toner images of different colors are superimposed on the intermediate transfer member. And transferring and fixing the multiple toner image to a recording material by secondary transfer (so-called tandem image forming apparatus),
(2) Examples include those in which a multiple toner image is directly formed on a recording material supported on an intermediate transfer member and this is fixed.

  As described above, according to the present invention, a plurality of toners having different colors can be used and an intermediate transfer member can be used to form an image, and a plurality of image densities having different image densities can be formed on the intermediate transfer member for each color toner subject to image formation condition adjustment. An electrophotographic color image forming apparatus that forms different toner patterns and adjusts the image forming conditions based on the result of measuring the density of the toner patterns. Color images that can be formed efficiently and with a small interval between adjacent toner patterns so that toner pattern density detection can be performed in a short time, and thus the waiting time for adjusting image forming conditions can be shortened accordingly. A forming apparatus can be provided.

FIG. 1 shows a schematic configuration of a color image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic block diagram of a control circuit in the image forming apparatus of FIG. 1, and a part of the control circuit is omitted.
The image forming apparatus of FIG. 1 is a tandem type full-color image forming apparatus.
This image forming apparatus includes an intermediate transfer member 8 in the form of an endless belt that is wound around pulleys 71, 72, and 73 and is driven to rotate counterclockwise in the figure (arrow direction in the figure). A cleaner CL for removing residual toner and the like on the intermediate transfer member 8 faces the lower left pulley 72 in the figure, and a secondary transfer roller 10 faces the pulley 71 on the right side in the figure. A fixing device 11 is installed above the secondary transfer roller 10. In FIG. 1, reference numeral 74 denotes a tensioning roller for the intermediate transfer member 8.

Between the pulleys 72 and 71, the yellow image forming unit Y, the cyan image forming unit C, the magenta image forming unit M, and the black image forming unit K are arranged in this order from the pulleys 72 to 71 with respect to the intermediate transfer member 8. Has been placed.
Each image forming unit includes a drum-type photoconductor 1, and a charging device 2, an image exposure device 3, a developing device 4, a primary transfer roller 6, and a residual toner on the photoconductor around the photoconductor. The cleaners 5 to be removed are arranged in this order. The primary transfer roller 6 faces the photosensitive member 1 with the intermediate transfer member 8 therebetween.

  The charging device 2 of each image forming unit receives a predetermined high voltage for charging the photoconductor from the output variable charging power supply YPW2, CPW2, MPW2, or KPW2 for the image forming unit under the instruction of the control unit CONT. It is applied at a predetermined timing. The developing roller 41 of the developing device 4 of each image forming unit receives a predetermined developing bias from the developing bias power supply YPW4, CPW4, MPW4, or KPW4 for the image forming unit at a predetermined timing under the instruction of the control unit CONT. Is applied.

A predetermined transfer voltage is also applied to the primary transfer roller 6 and the secondary transfer roller 10 of each image forming unit from a power source for each transfer roller (not shown) at a predetermined timing under the instruction of the control unit CONT.
Further, the image exposure device 3 in each image forming unit, the photoreceptor 1, the developing device 4, each drive motor (not shown) of the primary transfer roller 6, and the like, a motor that drives a pulley around which an intermediate transfer member is wound, and a secondary The transfer roller drive motor (both not shown), the fixing device 11 and the like are also operated at a predetermined timing under the instruction of the control unit CONT.

According to this image forming apparatus, an image is formed as follows.
In image formation, an image is formed in at least one of the image forming portions Y, C, M, and K according to an image to be finally formed. In the case where a full color image is formed using all of the image forming portions Y, C, M and K, for example, first, a yellow toner image is formed in the yellow image forming portion Y, and the primary transfer is performed on the intermediate transfer member 8. Is done.

  That is, in the yellow image forming unit Y, the photosensitive member 1 is rotated in the clockwise direction in the drawing, and the surface of the photosensitive member 1 is uniform by the charging device 2 to which a high voltage for charging is applied from the power source YPW2 (see FIG. 2). Is charged to a predetermined potential, and the image exposure device 3 is subjected to image exposure for a yellow image in the charged region, and an electrostatic latent image for yellow is formed on the photoreceptor 1. The electrostatic latent image is developed by a developing roller 41 to which a developing bias of a developing device 4 having yellow toner is applied to become a visible yellow toner image, and the toner image is a primary transfer roller 6 to which a primary transfer voltage is applied. Is transferred onto the intermediate transfer body 8.

  Similarly, a cyan toner image is formed in the cyan image forming unit C and transferred to the intermediate transfer member 8, and a magenta toner image is formed and transferred to the intermediate transfer member 8 in the magenta image forming unit M, and the black image forming unit. A black toner image is formed at K and transferred to the intermediate transfer member 8.

These yellow, cyan, magenta, and black toner images are formed at a timing when they are transferred onto the intermediate transfer body 8 in an overlapping manner.
Thus, the multiple toner image formed on the intermediate transfer member 8 moves toward the secondary transfer roller 10 by the rotation of the intermediate transfer member 8.

  On the other hand, the recording material S is supplied between the intermediate transfer body 8 and the secondary transfer roller 10 in synchronization with the multiple toner image on the intermediate transfer body 8 from a recording material supply unit (not shown), and the secondary transfer voltage. The multiple toner image is transferred onto the recording material S by the secondary transfer roller 10 to which is applied. Thereafter, the recording material S is passed through the fixing device 11, where the multiple toner images are fixed on the recording material S under heat and pressure, and a predetermined color image is formed.

In the image forming apparatus described above, the image forming conditions for making the image density appropriate can be adjusted as follows.
That is, when the image forming condition adjustment mode is entered at a preset timing in the control unit CONT, for example, when the image forming apparatus body is turned on or when a predetermined time has elapsed, under the instruction of the control unit CONT, As shown in FIG. 3, rectangular toner patterns (patch images) of magenta and black toner are alternately formed along the one ear portion of the intermediate transfer member 8 in the direction of progress of the intermediate transfer member, and yellow and A rectangular toner pattern (patch image) of cyan toner is alternately formed along the other ear portion of the intermediate transfer member 8 in the direction of progress of the intermediate transfer member surface.

In FIG. 3, PM1, PM2, PM3, and PM4 represent magenta toner patterns formed so that the image density decreases sequentially.
PK1, PK2, PK3, and PK4 represent black toner patterns formed so that the image density decreases sequentially.
PY1, PY2, PY3, and PY4 represent yellow toner patterns formed so that the image density decreases sequentially.
PC1, PC2, PC3, and PC4 represent toner patterns of cyan toner formed so that the image density decreases sequentially.

  Here, the four toner patterns PM1 to PM4 for the magenta toner are formed by switching the output potential of the photosensitive member charging power source MPW2 and switching the charging potential of the photosensitive drum 1 under the instruction of the control unit CONT. Is done. The toner patterns for the other color toners are similarly formed.

  The toner patterns of the respective color toners thus formed are detected by the image density detection device 9 provided on the intermediate transfer body 8, and the detection information is input to the control unit CONT. The control unit CONT sets in advance for each color toner. A charging power output for obtaining a photosensitive member charging potential when a toner pattern matching the target image density is formed is set. Thus, the image forming conditions that can obtain a predetermined image density are adjusted.

In the toner pattern formation described above, as shown in FIG. 3, toner patterns for magenta toner and black toner are alternately formed in the direction of progress of the intermediate transfer member surface, such as PM1, PK1, PM2, PK2,. Then, the toner patterns for the yellow toner and the cyan toner are also alternately formed in the advancing direction of the surface of the intermediate transfer member, such as PY1, PC1, PY2, PC2,. The black pattern PK1 is formed during the time required to switch the output voltage of the photoconductor charging power source MPW2 for forming the next magenta pattern PM2, and the pattern PM2 is a photoconductor for forming the next black pattern PK2. The two-color toner patterns are formed alternately and efficiently in a short time, as formed during the time required for switching the output voltage of the charging power source KPW2. Similarly, the yellow toner pattern and the cyan toner pattern are alternately and efficiently formed in a short time. Further, in the formed toner pattern group, the interval between adjacent patterns is short, and the detection of the toner pattern density by the image density detection device 9 can be performed in a short time.
Thus, the image forming conditions can be adjusted in such a short time, and an image forming apparatus that is easy to use for the user is realized.

  In the image forming apparatus described above, the formation of a plurality of toner patterns having different image densities of the respective color toners is performed by switching the output of the photosensitive member charging power source, in other words, by switching the photosensitive member charging potential. It is also possible to switch the bias potential, switch the exposure amount of the image exposure apparatus, or switch the peripheral speed ratio between the photosensitive member and the developing roller.

  In the image forming apparatus described above, the toner pattern is divided into two colors in the width direction of the intermediate transfer body 8, and the toner of each of the two colors is alternately formed in the direction of progress of the surface of the intermediate transfer body. However, the toner patterns of all colors may be formed while sequentially switching the respective color toner patterns in one row in the intermediate transfer member surface traveling direction.

The number of patterns of each color toner is not limited to the above four, but may be five or more, or two or more and three or less. If there are two or more, it is possible to adjust the image forming conditions.
Further, the color combination and order of the toner patterns to be formed are not limited to those described above, and can be arbitrarily determined. Two or more patterns may be formed between patterns of a certain color.

  INDUSTRIAL APPLICABILITY The present invention can be used to realize adjustment of image forming conditions for forming an image with an appropriate density in a short time in color image formation.

1 is a diagram illustrating a schematic configuration of an example of an image forming apparatus according to the present invention. FIG. 2 is a schematic block diagram illustrating a part of a control circuit of the image forming apparatus illustrated in FIG. 1. FIG. 6 is a diagram illustrating an example of toner pattern formation. FIG. 6 is a diagram illustrating an example of toner pattern formation time. It is a figure which shows the prior art example of toner pattern formation. It is a figure which shows the prior art example of toner pattern formation time.

Explanation of symbols

Y Yellow image forming unit 71, 72, 73 Pulley C Cyan image forming unit 8 Intermediate transfer member M Magenta image forming unit 9 Image density detecting device K Black image forming unit 10 Secondary transfer roller 1 Photoconductor 11 Fixing device 2 Charging device CL Cleaner 3 Image exposure device YPW2, CPW2, MPW2, KPW2
4 Developing Device Photoconductor Charging Power Supply 41 Developing Roller YPW4, CPW4, MPW4, KPW4
5 Cleaner Development bias power supply 6 Primary transfer roller CONT controller

Claims (6)

An image can be formed using a plurality of toners having different colors and using an intermediate transfer member, and a plurality of toner patterns having different image densities are formed on the intermediate transfer member for each color toner subject to image formation condition adjustment. An electrophotographic color image forming apparatus that adjusts image forming conditions based on the result of measuring the density of the toner, wherein the toner patterns for at least two colors of toner are alternately arranged in the direction of surface advance of the intermediate transfer member. A color image forming apparatus characterized by forming. The plurality of toners having different colors are four color toners, and the toner pattern for each of the four color toners is divided into two colors in the width direction of the intermediate transfer member, and each of the two color toners The color image forming apparatus according to claim 1, wherein the intermediate transfer member is alternately formed in a direction in which the surface of the intermediate transfer member travels. The color image forming apparatus according to claim 1, wherein the plurality of toner patterns of the same color are formed by switching a charging potential of an image carrier in the image forming apparatus used for forming the toner pattern. The color image forming apparatus according to claim 1, wherein the plurality of toner patterns of the same color are formed by switching a developing bias potential of a developing device in the image forming apparatus used for forming the toner pattern. The color image forming apparatus according to claim 1, wherein the plurality of toner patterns of the same color are formed by switching an exposure amount of an image exposure apparatus in the image forming apparatus used for forming the toner pattern. 6. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a tandem type color image forming apparatus.