JP2006039198A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus with which an amount of color misalignment is measured by separating light emitted from a single registration detection unit, and detecting registrations at two points on a belt. <P>SOLUTION: The registration detection unit is provided with a compound lens to separate light on the light emission side. Two points on the belt are irradiated with the separate rays of light. Registration detection patterns are disposed in the two positions on the belt. The registration detection patterns are alternately transferred with different detection-timings and at different times. Thus, color misalignment in a scanning direction and that in a conveying direction can be detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus including means for correcting a color misregistration amount of each superimposed color.

  Conventionally, each color misregistration correction unit superimposed in a color image forming apparatus detects color misregistration using two registration detection sensors.

  The registration detection sensors are arranged as shown in FIG. In the drawing, 900 is an intermediate transfer belt, 910 is a first registration detection sensor, 920 is a second registration detection sensor, 912 is a first registration pattern, and 922 is a second registration pattern.

  The intermediate transfer belt 900 is stretched by a driving roller 902, a driven roller 904, and a tension spring disposed in the belt. The surface of the applied rubber or the like and the back surface portion of the intermediate transfer belt 900 are gripped and rotated by a frictional force.

  On the other hand, a registration pattern is formed on the intermediate transfer belt 900 by an optical unit (not shown) and a process cartridge including a photosensitive drum and a developing unit.

  In the drawing, the first registration pattern 912 and the second registration pattern 922 are transferred to the left and right positions of the intermediate transfer belt 900. By the first registration detection sensor 910 and the second registration detection sensor 920 arranged at a position where these registration patterns can be detected, speed unevenness in the conveyance direction, image writing position, magnification in the scanning direction, It is possible to detect the writing position from the right end.

  Of the normal image writing position and magnification in the scanning direction, correction of color misregistration in the transport direction is performed by means for correcting the writing position of each color to be overlaid, and bending of scanning lines caused by the lens in the optical unit and the lens. A means for correcting the scanning line and the inclination of the photosensitive drum can be considered.

  First, the means for correcting the writing start position of the former need only have at least one registration detection sensor and a registration pattern, and the correction means such as bending and inclination of the latter requires two registration detection sensors and a registration pattern on the left and right.

  Next, correction of color misregistration in the scanning direction includes means for correcting the writing position at the left end or right end in the scanning direction and correcting the magnification of the scanning line. These correction means include two registration detection sensors and a registration pattern on the left and right. is necessary.

  The color misregistration correcting means corrects color misregistration due to temperature rise in the machine and distortion of the main body due to different installation conditions.

  The correction means described above corrects color misregistration in the transport direction and the scanning direction by using the left and right registration detection sensors and registration patterns except for a part.

  Further, the registration patterns 912/922 and the registration detection units 910/920 are arranged in the area of the image to be transferred to the transfer material. This is arranged as means for reducing errors more than when detecting and correcting near the both ends of the image when correcting the bending on the scanning line described above. Therefore, since it is arranged in the image transfer area 930 indicated by the broken line in the drawing, at least when the image to be transferred to the transfer material is formed on the intermediate transfer belt 900, the registration pattern 912 / 922 is not formed on the intermediate transfer member.

  Although not shown in FIG. 8 of the conventional example, the registration detection units 910 and 920 are attached so as not to be misaligned with the intermediate transfer belt 900. This is because when the positional deviation occurs, the level of the reflected light decreases and the registration detection pattern cannot be detected. Usually, these positional relationships are configured so as to be maintained with high accuracy and have a configuration such as means for adjusting the amount of light.

As a detection means for the registration detection, for example, there is a method described in Patent Document 1 below.
Japanese Patent Laid-Open No. 2002-023445

  However, in the conventional configuration, when the registration detection pattern 912/922 is configured and the registration detection sensor 910/920 corrects the color misregistration amount, at least two registration detection patterns and a registration detection sensor are required.

  These two sets of color misregistration detection means correct the color misregistration amount using registration detection sensors 910/920 and registration detection patterns 912/922 arranged on the left and right sides of the intermediate transfer belt 900, mainly in the scanning direction. It is used as a means to correct the amount of color misalignment. Of the color misregistration in the scanning direction, it is divided into means for detecting the deviation amount of the writing position at the left end or the right end, and means for detecting the deviation amount of the scanning magnification in the scanning direction of each color.

  Since these color misregistration correction means are configured to detect left and right in the scanning direction as described above, they are arranged at both ends of the intermediate transfer belt, and at least two registration detection sensors are required. For this reason, there is a problem that the cost for correcting the color misregistration is increased, and a space for arranging the registration detection sensor is required, which makes wiring complicated.

  Next, the relationship between the color misregistration correction means, the registration detection sensor, and the registration pattern is as follows. The color misregistration is corrected by reading at least two registration detection patterns.

  Among the color misregistration correction means, the color misregistration corrected by using two registration detection patterns and a registration detection sensor is firstly a magnification correction means in the scanning direction and secondly a correction means for the writing position in the scanning direction. Third, correction means for apparently halving the amount of color misregistration caused by the lens in the optical unit in the transport direction.

  Of these color misregistration correction means, the first and second correction means often have the same misalignment amount for the writing position and the misalignment amount for the scanning magnification. After that, the color misalignment of the writing position in the scanning direction at the left end or the right end is corrected.

  The color misalignment in the third transport direction can compensate for the color misalignment caused by the lens by correcting the writing position in the transport direction.

  Therefore, the color misregistration correction means in the transport direction and the scanning direction can correct the color misregistration by reading the left and right registration detection patterns 912/922 of the intermediate transfer belt and correcting the color misregistration of each color. .

  Further, the color misregistration detected by reading the registration detection patterns 912/922 arranged on the left and right in the scanning direction of the intermediate transfer belt 900 is obtained by reading the registration detection patterns arranged in different rows with respect to the transport direction. Color misregistration can be corrected.

  Therefore, in order to correct these color misregistrations, it is necessary to read out at least the registration detection patterns arranged at different positions in the column and to correct the color misregistration. Therefore, by arranging two registration detection sensors, There was a problem that the main body of the machine increased the cost.

  The present invention has been made in view of such problems, and a first object of the invention according to the present application is to perform color misregistration by reading different registration detection patterns in two columns by one registration detection sensor. In addition, in order to configure a single registration detection sensor to read different registration detection patterns in two columns, a single projection light is irradiated to irradiate different registration detection patterns in two columns. It is an object of the present invention to provide a color image forming apparatus that is more efficient and has less color misregistration, even if there is only one registration detection unit, by configuring the light detection means to diverge and reflect the registration detection pattern.

  The second object of the invention according to the present application is to read different registration detection patterns in two columns by one registration detection sensor, so that different registration detection patterns in each column can be detected alternately. The color image forming apparatus is provided in the same manner as when two registration detection sensors are arranged to correct the color misregistration.

  The third object of the invention according to the present application is, for example, that any one of the registration detection units provided at both ends of the conventional intermediate transfer belt is positioned during registration detection detection due to problems such as body rigidity. When the shift detection condition becomes unstable, a magnification shift in the scanning direction may occur. According to the means of the invention of the present application, a color image forming apparatus that does not cause a positional shift in the scanning direction is provided. Can be provided.

  Note that after detecting these registration detection patterns, the means for performing the correction operation is configured to correct the amount of color misregistration using the operation means described in Patent Document 1.

  The first configuration for realizing the object of the invention according to the present application is to split the irradiation light applied to the intermediate transfer belt from the light emitting portion of the registration detecting unit including at least one light emitting portion and the light receiving portion, and to receive the light receiving portion. The reflected light of two different columns is made incident.

  Two rows of registration detection patterns are formed on the intermediate transfer belt. Each registration detection pattern is arranged at a position where each light emitted from the light emitting portion of the registration detection unit and dispersed is reflected.

  In addition, the two rows of registration detection patterns are arranged so as not to overlap each other so that the reflected light of the two rows of registration detection patterns does not enter the light receiving unit at the same time.

  The amount of color misregistration in the scanning direction and the conveyance direction is detected by the registration detection unit and the registration detection pattern configured as described above.

  According to the above configuration, the registration detection patterns arranged so as not to overlap each other when the light emitted from the light emitting portion of one registration detection unit is dispersed and each light is reflected on the intermediate transfer belt. It is possible to detect.

  Accordingly, it is possible to detect the amount of color misregistration in the scanning direction and the conveyance direction with one registration detection unit, and provide a color image forming apparatus that corrects color misregistration with one registration detection unit configured at low cost. Is possible.

  In addition, since the amount of color misregistration in the scanning direction can be detected with a single registration detection unit, color images that do not cause color misregistration at each registration detection position misalignment placed on the left and right sides of the belt caused by changes in the rigidity of the main body. A forming apparatus can be provided.

  As described above, according to the present invention, the infrared light emitted from one registration detection unit 60 is dispersed to detect a registration detection pattern that passes through two points, thereby conveying and scanning directions. Color misregistration can be corrected.

  The color misregistration correction in the normal scanning direction is corrected by registration detection sensors arranged at the left end and the right end of the transfer material. In the configuration of the present invention, the range in which the color misregistration in the scanning direction is detected becomes small, but the color misregistration in the scanning direction can be sufficiently corrected by detecting the registration patterns at two positions.

  Further, the color misregistration in the scanning direction is corrected at least when the color image forming apparatus main body is shipped. Cases that must be corrected after shipment are color shifts due to temperature rise of the main body. This color shift amount may be a relatively large color shift in the scanning direction, and can be corrected by detecting registration patterns at two positions.

  Further, it is not necessary to correct a relatively small color misregistration amount, for example, a color misalignment in the scanning direction caused by the photosensitive drum generated when the process cartridge is replaced.

  That is, the color misregistration in the scanning direction has fewer factors causing the color misregistration than the color misregistration in the transport direction. Therefore, the desired object can be achieved by correcting the large color misregistration.

  In addition, since one registration detection unit can correct color misregistration in both the scanning direction and the conveyance direction, it is advantageous in terms of cost.

  Embodiments of the present invention will be described below with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 6 show Embodiment 1 of the present invention. First, an embodiment of a color image forming apparatus in which Embodiment 1 of the present invention is embodied will be described with reference to FIG.

  In the color image forming apparatus of this embodiment, the process cartridges 10y, 10m, 10c, and 10k for four colors can be attached to and detached from the corresponding development forming stations, and optical units 20y, 20m, 20c, and 20k, an intermediate transfer body unit 30, a transfer material transport unit 40, a fixing unit 50, and the like.

  The process cartridges 10y, 10m, 10c, and 10k have the same structure, and a photosensitive drum 12, a charging unit 13, a developing device 14, and a cleaning device 15 that are electrophotographic photosensitive members are integrally configured.

  The intermediate transfer body unit 30 transfers the toner image formed on each photosensitive drum 12 to the transfer belt 31, a transfer belt 31 that is an endless belt body, three rollers 32, 33, and 34 that rotatably support the transfer belt 31. And a secondary transfer roller 36 that further transfers the toner image transferred onto the transfer belt 31 to the transfer material p.

  The transfer material transport unit 40 includes a pickup roller 43, a feed roller 44, a transport roller 45, a registration roller 46, and the like that transport the transfer material p from each paper feed cassette 41 or the paper feed tray 42 to the secondary transfer region. I have.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52, and performs fixing by applying heat and pressure to the toner image on the transfer material p.

  In the above configuration, first, in the process cartridge 10k of the first color, for example, black, a latent image is formed by the laser light 22 irradiated from the optical unit 20k after the photosensitive drum 12 is uniformly charged by the charging unit 13, and this The latent image is developed by the developing device 14 to form a toner image.

  The toner image formed on the photosensitive drum 12 is primarily transferred onto the transfer belt 31 by the action of the primary transfer roller 35. The photosensitive drum 12 having undergone the primary transfer is cleaned by the cleaning device 15 and used for the next image formation.

  A similar image forming process is performed in each of the process cartridges 10y, 10m, and 10c for y, m, and c to form toner images of the respective colors, which are sequentially transferred onto the previously formed toner images.

  On the other hand, the transfer material p is transported from the paper feed cassette 41 or the paper feed tray 42 to the secondary transfer region by the transfer material transport unit 40, and the toner image formed on the transfer belt 31 by the action of the secondary transfer roller 36. Is transferred to the transfer material p. The transfer material p to which the toner image is transferred is conveyed to the fixing unit 50, where the toner image is fixed at the nip portion between the fixing roller 51 and the pressure roller 52, and is discharged onto the discharge tray 56 by the discharge roller 55. Is done.

  2 and 3 are diagrams that best illustrate the present embodiment, and FIG. 2 is a diagram illustrating the configuration of the registration detection unit.

  In the figure, 31 is an intermediate transfer belt, 32 is a driving roller, 38 is a coupling, 33 is a driven roller, 20 is a registration detection unit, 60 is a sheet metal for the registration detection unit, and 70 is an intermediate transfer belt. 1 is a light emitter that irradiates light, 72 is a compound eye lens that splits light from the light emitter, and 71 is a light receiver that receives the light reflected by the intermediate transfer belt 1.

  Next, the amount of color misregistration detected by the registration detection unit 60 will be described.

  The intermediate transfer belt 31 is stretched by a driving roller 32, a driven roller 33, the roller 34 described above, and a tension spring (not shown), and the back surface of the intermediate transfer belt 31 is driven by a thin film rubber formed on the driving roller 32. The roller 32 is configured to grip. When the driving roller 32 rotates due to the frictional force between the thin film rubber surface of the driving roller 32 and the intermediate transfer belt 31, the intermediate transfer belt 31 also rotates.

  A coupling 38 is attached on the shaft of the driving roller 32, and the driving roller 32 receives a rotating force by a driving unit having a motor on the main body side (not shown) and a coupling unit on the main body side. The intermediate transfer belt 31 is rotated and conveyed.

  As the intermediate transfer belt 31 is rotated and conveyed, registration detection patterns formed on the intermediate transfer belt 31 are sequentially sent toward the registration detection unit 60.

  On the other hand, on the intermediate transfer belt 31, as described above with reference to FIG. 1, the optical unit 20 and the process cartridge 10 are arranged at each station. An image formed on the photosensitive drum 12 by the optical unit 20 and the process cartridge 10 is configured to be primarily transferred onto the intermediate transfer belt 32.

  Accordingly, a registration detection pattern for detecting color misregistration is also formed on the intermediate transfer body belt 31 and sequentially passes through the detection unit of the registration detection unit 60 by the rotational conveyance of the intermediate transfer body belt 31 as described above.

  On the other hand, the registration detection unit 60 includes a light emitting body 70 such as an LED, a light receiving body 71 such as a photodiode, a compound eye lens 72, and holders 62/63.

  First, the light-emitting side holder 62 and the light-receiving side holder 63 are unitized by the sheet metal 61. Among the holders, a light emitting body 70 and a compound eye lens 72 are arranged on the light emitting side holder 62. The light emitter 70 is a light emitter that emits infrared light, such as an LED. The infrared light emitted from the light emitter 70 is split by the compound eye lens 72.

  The split infrared light is split into an optical path 81 and an optical path 82 in the figure, and is reflected on the intermediate transfer belt 31 and then enters the light receiver 71.

  The reflection positions at this time are reflected at the reflection points 81-a and 82-a in the reflection point region 80, respectively. This reflection point is configured so that the two reflection points 81-a and 82-a do not overlap. Further, although the amount of color misregistration can be corrected by having a certain amount of interval, it is only necessary to detect a displacement of a registration detection pattern, which will be described later. There is no.

  The light receiving body 71 is attached to the light receiving side holder 63 and is configured so that the light emitting side light emitting body 70 and the compound eye lens 72 irradiate a predetermined position, and completely receives the reflected light. Placed in position.

  While the registration detection unit 60 is operating, infrared light is emitted from the light emitter 70 toward the intermediate transfer belt 31, and reflected light is incident on the light receiver 71. However, a registration detection pattern is formed. In this state, the light receiving level of the photoreceptor 71 is set to the initial level.

  Next, a means for detecting the registration detection pattern 90 by the registration detection unit 60 will be described with reference to FIGS.

  In the drawing, registration detection patterns are formed at positions passing through the reflection points 81-a and 82-a on the intermediate transfer belt 31. As for the registration detection pattern, a first registration detection pattern 91 and a second registration detection pattern 92 are formed, and the respective registration detection patterns are alternately formed so as not to overlap each other.

  Therefore, the registration detection pattern that passes through the reflection points 81-a and 82-a has a registration detection pattern 92 of 82-a when at least the first registration detection pattern 91 passes through the 81-a point. It is formed so as not to pass the point.

  Each of the registration detection patterns is composed of four colors, and is formed, for example, in the color order of Bk, C, M, and Y. Four registration detection patterns are detected as one lump, and a first registration detection pattern 91 is detected. Next, a second registration detection pattern 92 in which the four patterns are formed as one lump is detected.

  Although the detected pattern pitch will be described in detail later, it is detected as D in the figure.

  Further, L1L2L3 shown in the figure indicates a gap between the first registration detection pattern 91 and the second registration detection pattern 92. Here, the distance D is compared with the gap L1L2. Since D <L1 or L2, L1 · L2 is detected unless the next pattern is detected for a time longer than the time D.

  After the measurement of the color misregistration amount by the registration test is started, the time lengths of D and L1 · L2 are compared, and when L1 · L2 is detected, the first registration detection pattern 91 and the second registration detection pattern 92 Switching can be detected.

  In other words, the registration detection pattern detection procedure is shown in FIG.

  In FIG. 4, when the registration detection mode is entered at the registration detection start 101, the process cartridge 10 optical unit 20 for driving the intermediate transfer belt 31 and creating the registration detection pattern 90 operates. In the above operation, when a registration detection pattern is formed at 102, the registration detection unit 60 starts detection at 103 at the same time.

  When the registration detection unit 60 operates, the registration detection pattern does not pass through the reflection points 81-a and 82-a at that time, so the surface of the intermediate transfer belt 31 is being measured. The reflectance at this time becomes the initial reference value.

  When the intermediate transfer belt 31 further rotates, the first registration detection pattern 90 is detected at 104, and the first registration detection pattern 91 among the registration detection patterns 90 formed on the intermediate transfer belt 31 is reflected points 81. The first registration detection pattern 91 is detected by passing through the point -a.

  When the first registration detection pattern 91 passes the reflection point 81-a, the reflectance changes with respect to the initial reference value, and the color misregistration amount of each color of the first registration detection pattern 91 is detected.

  In the registration detection pattern 90, the amount of color misregistration is determined by an arrangement and pitch measurement method described later. The registration detection pattern 90 formed here is configured in the order of Y, M, C, and K, for example. Therefore, the amount of color misregistration is detected by reading each pitch shift.

  With this detection means, the first registration detection pattern 91 is read. At this time, the second registration detection pattern 92 is not sent to the reflection point 82-a. The amount of color misregistration is not detected.

  While reading the first registration detection pattern 91, it is detected at 105 whether or not the detection value of the registration detection pattern 90 is at an initial level for a certain period of time.

  That is, the switching between the first registration detection pattern 91 and the first registration detection pattern 92 is performed by arranging the space L provided between the patterns, so that the reflectance detected by the registration detection unit 60 is the initial value. After the change from the value, when it returns to the initial stage for a certain time, it can be detected that the detection of the first registration detection pattern 91 is completed.

In this detection time, since the speed of the intermediate transfer belt 31 is sent at a substantially constant speed, when the detection time is t and the speed of the intermediate transfer belt 31 is v,
t = L / v
It becomes. Since the speed v is substantially constant, the time based on the space amount L can be detected stably, and the switching point between the first registration detection pattern 91 and the second registration detection pattern 92 can be detected.

  When the time t detected by the space amount L elapses, the second registration detection pattern 92 passes through the reflection point 82-a. At 106, the second registration detection pattern 92 can be detected, and the detection of 92 in the registration detection pattern is completed by reading the difference in reflectance as in the case of detection of the first registration detection pattern 91.

  At the same time, since the space amount L arranged behind the second registration detection pattern 92 is detected by 107, the end of detection of the second registration detection pattern 92 is detected in the same manner as the criterion 105. .

  In 105 and 107, the time of the space L is measured, but when the next registration detection pattern 90 is not detected after waiting for a predetermined time, the process proceeds to 108 and the detection of the registration detection pattern 90 is completed, or If the registration detection pattern 90 is not transferred onto the intermediate transfer belt 31 due to some trouble, the registration detection ends.

  Further, when the registration detection pattern 90 is detected again, it is assumed that the first registration detection pattern 91 is detected at 104, and a plurality of registration detections are performed.

  In this manner, the registration detection patterns 90 that alternately pass through the reflection points 81-a and 82-a are detected to be the first registration detection pattern 91 and the second registration detection pattern 92, respectively. Thus, the amount of color misregistration can be detected.

  Here, it is assumed that the first registration detection pattern 91 passes through the reflection point 81-a, but even if the second registration detection pattern 92 passes through the reflection point 82-a first, the color There is no problem in detecting the amount of deviation, and the registration detection patterns 90 that pass therethrough are simply read as the first and second registration detection patterns for convenience.

  Further, each registration detection pattern 90 is read a plurality of times and averaged so as to correct the reading error of the registration detection unit 60 and to cancel the speed unevenness in the conveyance speed of the intermediate transfer belt 31. It is configured.

  Next, a means for correcting color misregistration in the first registration detection pattern 91 and the second registration detection pattern 92 will be described with reference to FIGS.

  First, referring to FIG. 5, a description will be given of means for correcting the positional deviation of the writing start position of each color that occurs in the transport direction. In the drawing, among the first registration detection patterns 91, the Bk color 91k registration detection pattern is drawn at the head, and the CMY color 91c91m91y registration detection pattern is drawn at a predetermined timing.

  Here, the registration detection pattern 90 is composed of a combination of straight lines and diagonal lines. Of these combinations, the straight line portion is used to detect the writing position deviation in the conveyance direction. The straight line is used to correct the color misregistration. This is because the color misregistration correction is not affected.

  On the other hand, the diagonal line detects the amount of color misregistration in the scanning direction, which will be described later.

  When the first registration detection pattern 91 passes through the reflection point 81-a, the respective intervals when the Bk color 91k is used as a reference are detected by the reflection of the respective colors. The detected intervals at this time are 91 kc-1, 91 km-1, and 91 ky-1.

  For example, 91kc-1 represents the time from detection of 91k which is the Bk registration detection pattern to detection of 91c which is the C registration detection pattern.

  Therefore, if the deviation of the light irradiation position of the optical unit 10 irradiating the photosensitive drum 20, the rotation unevenness of the photosensitive drum 20, and the like, which are causes of color misregistration at the writing position in the transport direction, coincide with each other, Bk The interval 91kc-1 and 91km-1 with respect to the reference value is 2 times 91kc-1 = 91km-1, and similarly 3 times 91kc-1 should be 91ky-1. Since the amount of deviation is the amount of color misregistration at the writing position in the transport direction, correction can be made based on this detection result.

  This transport direction correction means can be corrected by detecting either the first registration detection pattern 91 or the second registration detection pattern 92, and the same correction can be made by taking an average value from both results. It is.

  Further, the switching between the first registration detection pattern 91 and the second registration detection pattern 92 is based on the above-described determination means for the space amount L, and at least the space amount L is a registration detection pattern between two colors. Is also configured to be long.

  That is, since the relationship kc <L is established, if the registration amount pattern 92 having a reflectance different from the next initial value is detected after the space amount L is detected, the detected pattern is detected as 92k. The second registration detection pattern 92 can be detected, and the first registration detection pattern 91 and the second registration detection pattern can be distinguished.

  In the same figure, the registration detection pattern in the state where there is no color misalignment in the scanning direction is described. However, even if there is a color misalignment in the scanning direction, the conveyance direction is in the ratio of 91 kc-1 and 91 km-1 / 91 ky-1. It is possible to correct the writing position.

  Therefore, the order of correction is not particularly limited in the transport direction and the scanning direction.

  Next, correction means in the scanning direction will be described with reference to FIG.

  In the scanning direction correction means, the reflected light of the oblique line in the first registration detection pattern 91 is adopted and corrected, so that the pattern next to the first detected pattern in the transport direction is corrected for color misregistration in the scanning direction. Therefore, the first detected pattern and the even-numbered pattern are detected and corrected.

  First, the intervals between the first detected pattern, the second detection pattern, and the fourth detection pattern are detected as respective time differences 91kk-2 and 91kk-2. Similarly, the interval between the first detection pattern and the sixth and eighth detection patterns is 91 km-2 / 91ky-2, respectively.

  On the other hand, since the second registration detection pattern 92 is detected in the same manner, four intervals of 92 kk-2 / 92 kk-2 / 92 km-2 / 92 ky-2 are detected.

  The time differences detected here are compared. First, since the calculation is based on Bk, when the time difference between 91 kk−2 and 92 kk−2 is calculated, the color shift is 0 when the difference is 0.

  Even if a difference occurs, a shift Zkk occurs as shown in FIG.

(91kk-2)-(92kk-2) = Zkk
For example, when comparing 91 kk-2 and 92 kk-2, there is a color shift in the scanning direction of Black, and if the color shift occurs on the 92 kk-2 side, this is a color shift in the scanning direction. Black is shifted to the left. Therefore, when an oblique line for reading the deviation in the scanning direction is read at the reflection point 82-a, it is read as if it is shifted downward, and 91kk-2 has a longer time axis than 92kk-2. When this time difference is read as (91 km−2) − (92 km−2), a difference Zkk is generated as shown in FIG.

  In the figure, the 91k and 92k registration detection patterns are arranged at the same position so that the difference Zkk can be easily understood.

  If this oblique line is configured with an inclination of 45 °, the color misregistration amount in the scanning direction is dkc. That is, Zkk = dkk.

  As shown in the figure, D + dkk is detected as the color misregistration amount in the scanning direction from the above deviation amount. This is the color misregistration amount in the scanning direction of the Black station, that is, the time difference, and D + dkk of Black is used as a reference in the scanning direction.

  On the other hand, Cyan can detect a color shift in the scanning direction as well. Here, if there is no deviation, Zkm = 0, that is, Zkm = dkm = 0, so D + 0.

  Therefore, when Cyan and Black are compared and D + dkk vs. D + dkk and Zkk is calculated as 0, it becomes D + dkk vs. D, and scanning of Cyan is widened by dkk, and correction is required.

  The correction amount detected here can be calculated in the same manner as the time difference. In this case, the correction is made so that the color misregistration amount of the scanning width in the Cyan scanning direction becomes small. By this correction, the scan widths of Cyan and Black can be corrected, and at the same time, the writing position in the scanning direction is corrected with reference to the left or right edge of the image.

  Similarly, with the black as a reference, the same detection and correction are performed for the remaining two colors, and the correction of the color misregistration amount is completed.

  With the method described above, it is possible to detect the color misregistration in the scanning direction by one registration detection unit 60 and correct the color misregistration amount. However, the color misregistration in the scanning direction is essentially the left end with respect to the transfer material. The maximum color shift on the right end side.

  Since the detection position this time is between the reflection points 81-a and 82-a, it is necessary to increase and correct the detection accuracy because the width is narrower than the distance between the left end and the right end of the transfer material. .

  Further, the switching between the first registration detection pattern 91 and the second registration detection pattern 92 can be determined by the method described above in the transport direction based on the above-described determination unit for the space amount L.

  Although it is possible to correct the transport direction using the configuration of the present invention, the description in this embodiment will not be given.

  Further, since the registration detection pattern 90 is an arbitrary detection pattern, the detection pattern is not particularly limited as long as the color misregistration amount in the transport direction and the scanning direction can be detected.

  Next, a second embodiment of the registration detection pattern will be described with reference to FIG.

  In the figure, since the configuration of the registration detection pattern is different from that of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described.

  In the figure, the difference from the first embodiment is the interval between the first registration detection pattern and the second registration detection pattern.

  First, reference numeral 191 shown in FIG. 7 denotes a first registration detection pattern, and 192 denotes a second registration detection pattern.

  The first registration detection pattern 191 and the second registration detection pattern 192 are formed on the intermediate transfer body belt 31. Each pattern is arranged at a position passing through the reflection point 81-a and the reflection point 82-a, and is formed so that the registration detection patterns do not overlap each other. While passing, the other registration detection pattern does not pass through the reflection point.

  Further, the registration detection pattern is composed of four colors, and is formed in, for example, a color order of Bk, C, M, and Y. Four registration detection patterns are detected as one lump, and a first registration detection pattern 191 is detected. Next, a second registration detection pattern 192 in which the four patterns are formed as one lump is detected.

  The pitch of the detected pattern is configured as P1P2 as shown in FIG. P1 represents the interval of the first registration detection pattern 191 and P2 represents the interval of the registration detection pattern 192.

  These intervals P1 are the same intervals in the first registration detection pattern 191, while the intervals P2 are similarly configured in the second registration detection pattern 192 at the same intervals.

  The interval between P1 and P2 is configured such that at least one of the intervals is larger. For example, since it is configured so that P1 <P2, each interval is detected to determine whether the first registration detection pattern 191 is read or the second registration detection pattern 192 is read. It becomes possible to do.

  It should be noted that P1 and P2 are configured to be sufficiently large or sufficiently small with respect to D for determining the displacement of the registration detection pattern. It is possible to determine whether or not

  With the configuration of the second embodiment, it is possible to detect which one of the first registration detection pattern and the second registration detection pattern is detected, and whether the detected pattern is switched.

  As described above, the infrared light emitted from one registration detection unit 60 is dispersed to detect the first registration detection pattern and the second registration detection pattern passing through two points, thereby conveying Correction of color misregistration in the direction and the scanning direction is possible.

FIG. 1 illustrates an image forming apparatus. Configuration diagram for detecting a registration detection pattern that best represents the first embodiment Cash register pattern layout Flow chart for reading cash register pattern A figure that instructs the detection of the writing position in the transport direction by the registration detection pattern The figure which instruct | indicates the detection of the write-out position of a scanning direction with a registration detection pattern The figure which instruct | indicates the detection of the write-out position of a scanning direction with a registration detection pattern Diagram for explaining the second embodiment A diagram for explaining a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Process cartridge 20 Optical box 31 Intermediate transfer body belt 60 Registration detection unit 70 Light emitting body 71 Photoreceptor 72 Compound eye lens 81-a Reflection point 82-a Reflection point 91 First registration detection pattern 92 Second registration detection pattern

Claims (7)

  It is formed of a container housing that holds a plurality of photoconductors, a process cartridge having a charging unit and a developing unit, toners, and the like, and a plurality of optical units having an optical system for forming an image on the photoconductor. In a color image forming apparatus that sequentially forms an image on a transfer material electrostatically attracted to an electrostatically attractable belt, a means for correcting the amount of color misregistration drawn on each intermediate transfer body belt from each photoconductor A color image forming apparatus configured to be able to read at least two rows of registration patterns by a registration detection unit having at least one means for emitting light and means for receiving light.   The two rows of registration patterns are formed on an electrostatically attractable belt, arranged so as not to be adjacent to each other in the belt conveyance direction, and configured to be alternately detected by the registration detection unit. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus.   The intervals between the individual registration patterns of the two rows of registration patterns are arranged at predetermined intervals, and the intervals between the first registration pattern and the second registration pattern are different from at least the individual registration pattern intervals. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is configured as follows.   4. The structure according to claim 1, wherein, among the two rows of registration patterns, each interval of the first registration pattern is different from each interval of the second registration pattern. 5. The color image forming apparatus described.   When one of the two registration patterns cannot be detected, the image writing position in the belt conveyance direction based on the detection result of either one The color image forming apparatus according to claim 1, wherein the color image forming apparatus is used only for detection of color.   It is formed of a container housing that holds a plurality of photoconductors, a process cartridge having a charging unit and a developing unit, toner, and the like, and a plurality of optical units having an optical system for forming an image on the photoconductor. In a color image forming apparatus that sequentially forms an image on a transfer material electrostatically attracted to an electrostatically attractable belt, a means for correcting the amount of color misregistration drawn on each intermediate transfer body belt from each photoconductor A color image forming apparatus, wherein the registration detecting unit for detecting the color misregistration amount includes at least one light emitting means, a light receiving means, and a means for dispersing light emitted from the light emitting means.   The light emitted from the registration detection unit is dispersed by a compound eye lens, and irradiates one of the positions on the first registration pattern and the second registration pattern on the intermediate transfer belt, and the irradiation light described above is emitted. 7. A color image forming apparatus according to claim 6, wherein the color image forming apparatus is configured to reflect on an intermediate transfer belt and to receive the reflected light into a light receiving means.

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