JP2004145077A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus whose productivity is improved by outputting a highly precise image with the highly precise alignment of the image of each color by solving problems in the conventional detecting system of a color slippage amount. <P>SOLUTION: In the image forming apparatus provided with an image carrier 1 to carry a latent image, an exposure means 3 to write in the latent image on the image carrier 1, a developing means 4 to visualize it by supplying the latent image with toner and a transfer means 5 to transfer the visible image of the image carrier 1 to a recording medium, the transfer means 5 is provided with a transfer member 51 consisting of a belt-shaped member, and the image carrier 1 and the transfer member 51 are respectively provided with an information rewriting means constituted of write-in means 112 and 512 possessing a rewritable information write-in area in the subscanning direction of each surface and to write in information in each information write-in area, detecting means 113 and 513 to detect the information and erasing means 111 and 511 to erase the information. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic process, and more particularly, to a color image forming apparatus that forms a color image.
[0002]
[Prior art]
The tandem type color image forming apparatus has an advantage that the printing speed is high, but has a disadvantage that it is difficult to perform color matching of each color. For this reason, for example, color misregistration of each color is likely to occur under the influence of an error due to the attachment or the eccentricity of each photoconductor. Therefore, in recent years, many proposals for preventing such color shift have been made.
[0003]
For example, a technique is disclosed in which a toner image as a detection mark is transferred to a transfer member such as a transfer belt, and these are detected by an optical sensor to determine the amount of color misregistration between each color. One of them uses a CCD line sensor as a reading means (for example, see Patent Document 1). In some cases, the detection mark is formed in a chevron shape and detected by a reflection type optical sensor (for example, see Patent Documents 2 and 3). Image registration correction of each color is performed based on such detection information.
[0004]
However, in the above technique, since the detection of the image pattern by the toner transferred to the transfer member is used, a sharp detection signal is generated due to toner scattering when the image pattern is transferred as a detection mark to the transfer member. There is a first problem that it is difficult to obtain. In addition, in the future, if the spot diameter of the optical sensor is reduced or the sensor sensitivity is sharpened for the purpose of more accurate detection for outputting a high-definition image, the image becomes more susceptible to scattering toner.
In addition, the second problem that the running cost is increased where the user does not intend to consume the toner for forming the detection mark, and the third problem is that the discharged toner increases due to the cleaning of the toner, which is not environmentally preferable. There is a point.
Further, when a detection mark is formed in the image forming area of the transfer member to perform the detection operation, it is necessary to perform a series of detection operations during the initial operation other than the print operation or during the print operation, and the user needs to perform a series of detection operations. There are a fourth problem that the printing operation is delayed in response to the print request and a timing of performing the detecting operation is restricted.
Conversely, when the detection mark is formed in the non-image forming area of the transfer member (for example, at the end of the transfer member or the back surface of the transfer member), the deterioration of the image due to the scattering of the toner and adhering and transferring to the paper may occur. There is a fifth problem that is likely to occur.
[0005]
Further, as another problem, as disclosed in Patent Document 4, it has a plurality of photoconductors and a plurality of transfer rotators, and includes a transfer rotator and a photoconductor, or a transfer rotator and a transfer rotator. In the method called the slip transfer method, in which the speed difference between the drive source and the drive source is regulated, even if the rotational speeds of both drive sources are set to the prescribed values, the load fluctuation of the rotating body due to the intrusion of paper or the like at the actual transfer position. There is a sixth problem that it is not known whether the speed difference is constant due to a speed change due to slip with the drive source.
[0006]
[Patent Document 1]
JP-A-6-18796
[Patent Document 2]
JP-A-6-118735
[Patent Document 3]
JP-A-10-198110
[Patent Document 4]
JP 2001-265081 A
[0007]
[Problems to be solved by the invention]
In view of the above problems, the present invention solves the problems in the conventional method of detecting the amount of color misregistration, outputs a high-definition image by high-accuracy registration of each color image, and can improve the productivity. It is an object to provide a forming apparatus.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes an image carrier for carrying a latent image, an exposure unit for writing the latent image on the image carrier, and a toner on the latent image on the image carrier. And a transfer unit for transferring a visible image of the image carrier to a recording medium, wherein the transfer unit includes a transfer member including a belt-shaped member. The image carrier and the transfer member each have an information writing area rewritable in the sub-scanning direction on each surface, and write means for writing information in each information writing area; and a detection means for detecting information. An image forming apparatus is provided with an information rewriting unit including a unit and an erasing unit for erasing information.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the writing unit included in the image carrier includes a main scanning line of exposure light that the exposure unit irradiates on the surface of the image carrier. And the detecting means provided in the image carrier and the writing means provided in the transfer member are arranged on the same main scanning line at a transfer position between the image carrier and the transfer member. Image forming apparatus.
[0009]
According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the information writing area is arranged outside the image forming area.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the operation of the information rewriting means is performed at the time of image formation.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image carrier and the transfer member each include a plurality of the information rewriting units in a main scanning direction. It is.
[0010]
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the image is formed based on a detection signal of a detection unit of the image carrier and a detection unit of the transfer member. An image forming apparatus detects a speed difference between a carrier and the transfer member.
According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, an image in which a rotation speed of the image carrier is controlled by detecting a speed difference between the image carrier and the transfer member by the detection unit. It is a forming device.
[0011]
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the information recorded in the information writing area provided in the image carrier and the transfer member is multi-valued. The image forming apparatus is information.
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the image carrier and the transfer member include information rewriting means using different information recording methods. is there.
[0012]
According to a tenth aspect of the present invention, a plurality of image carriers that carry a latent image, an exposure unit that writes a latent image on each of the image carriers, and a toner that supplies toner to the latent image on the image carrier are provided. An image forming apparatus comprising: a developing unit for visualizing; and a transfer unit for transferring a visible image of the image carrier to a recording medium, wherein the transfer unit includes a transfer member including a belt-shaped member. The image carrier and the transfer member each have an information writing area rewritable in the sub-scanning direction on each surface, and each image carrier has a writing unit for writing information in each information writing area; The transfer member includes a writing unit for writing information in the information writing area, a detecting unit for detecting information, Information rewriting means consisting of erasing means for erasing That is an image forming apparatus.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the transfer member is arranged at a position where the detecting means is an integral multiple of the circumference of a driving roller of the transfer member. Device.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a main part of an image forming apparatus according to the present invention. A charging unit 2, an exposure unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and a fixing unit 7 are arranged around a photoreceptor 1 as an image carrier.
Although the photoconductor 1 is shown as a drum, it may be a belt. The charging means 2 may be provided with a corotron type charger as shown in FIG. 1 or may be provided with a charging roller for charging the photosensitive member 1 in contact with or in proximity thereto. The developing means 4 includes developing devices 4Bk, 4C, 4M, and 4Y each having a toner of each color of black (Bk), cyan (C), magenta (M), and yellow (Y). These developing devices may be revolver type developing devices. The transfer unit 5 includes an intermediate transfer body 51, a secondary transfer roller 52, and a transfer belt 53.
The image forming operation of such an image forming apparatus is as follows. First, the surface of the photoconductor 1 is uniformly charged by the charging unit 2. A latent image is formed on the charged surface of the photoconductor 1 by exposure light of the exposure unit 3 based on image information, and then developed by a developing device 4 of any corresponding color. The toner image thus formed on the photoconductor 1 is transferred to the intermediate transfer body 51. After the transfer, the photoreceptor 1 is cleaned by a cleaning unit 6 to remove toner and the like remaining on the surface. Thereafter, the above-described image forming operation is repeated for an image of a different color from the above, and the toner images of the respective colors are superimposed on the photoconductor 1. Finally, the color toner image formed by superimposing the four colors on the intermediate transfer member 51 is collectively transferred and fixed by a secondary transfer roller 52 and a transfer belt 53 onto a sheet conveyed from a sheet feeding unit (not shown). The fixing is performed by means 7.
[0014]
Next, a description will be given of information rewriting means provided in the image forming apparatus for eliminating color misregistration of each color toner image. The information rewriting means includes: (1) an information rewriting means including a recording head, a reproducing head, and an erasing head for performing S pole and N pole magnetic recording on a magnetic tape like a magnetic recording type tape recorder. (2) Information rewriting means, such as a thermal medium, in which heat is applied to a heat-sensitive coloring layer by a heating element to record, and a color image is detected by an optical sensor and erased by the heating element. (3) An information rewriting means comprising a recording, reproducing and erasing head using magneto-optical writing called MO. (See http://www.mo-formum.gr.jp/japanese/technology/genri01.htmlhttp://mo.fujitsu.com/products/whatsmo/mowrite.html and CD-W4, etc.). A phase change optical recording system utilizing a change in light reflectance due to a crystal-amorphous phase change of a substance used in DVD-RW. (See http://www.sony.co.jp/Products/DataMedia/products/CDRW/phase_change.html, etc.). Using such information rewriting means, information having the same function as the detection mark shown in the related art is written, and the information is detected to detect a color shift.
[0015]
FIG. 2 is a diagram schematically showing a magnetic recording type information rewriting means. An information writing area is provided in a part of the intermediate transfer body 51, and a recording layer 51a made of a magnetic material is provided on a surface layer thereof. The recording layer 51a is a layer made of a magnetic material similar to a tape recorder generally used for recording audio, video, data, and the like, and is formed by applying or depositing a magnetic material on the surface of the intermediate transfer body 51. Alternatively, it is possible to form a magnetic tape that has already been completed in those steps by sticking it to the intermediate transfer body 51.
The erasing head 11, the writing head 12, and the detection head 13 are provided side by side in the sub-scanning direction of the intermediate transfer body 51 so as to contact the recording layer 51a formed as described above. The erasing head 11 causes the erasing head coil 11a and the erasing head core 11b to generate magnetic field lines in the erasing head gap 11c at which high-frequency N poles and S poles are switched, thereby changing the polarity of the magnetic material of the recording layer 51a passing through the erasing head gap 11c. Neutralize.
The write head 12 causes a binary pattern signal to flow through the write head coil 12a, causes the write head core 12b to generate a write signal magnetic flux in the write head gap 12c, and causes an S pole and an N pole to be in contact with the recording layer 51a. Write an alternate pattern with. As this binary pattern signal, a binary pattern of S-pole and N-pole at temporally equal intervals is recorded by a signal of a fixed cycle. Although not shown, if a signal for switching the S-pole and the N-pole at equal intervals is generated by a unit (for example, an encoder) that measures the amount of movement of the intermediate transfer body 51, the distance between the S-pole and the N-pole is equal. An S pole and N pole binary pattern are recorded.
The detection head 13 can take out a binary pattern written on the recording layer 51a contacting at the detection head gap 13c as a binary pattern signal by the detection head core 13b and the detection head coil 13a.
[0016]
As shown in FIG. 2, the recording layer 51a includes an old binary pattern area upstream of the erase head 11, a non-binary pattern area between the erase head 11 and the write head 12, and a detection head 13 and is divided into a new binary pattern area until it contacts the erase head 11. By continuously performing the rewritable magnetic recording in this manner, the binary pattern is always refreshed, so that even if the belt of the intermediate transfer body 51 expands and contracts with time, a binary pattern at regular intervals is continuously generated. Can do things.
[0017]
FIG. 3 is a diagram showing another magnetic recording type information rewriting means. The write head 12 and the detection head 13 are integrated into a write detection head 21. A binary pattern signal is applied to the write head coil 21a, and the binary pattern is written to the recording layer 51a at the write detection head gap 21d. On the other hand, when the binary pattern has been written in advance, the signal is detected by the detection head coil 21b. In this way, even with one head, two functions of writing and detection can be executed by mode switching.
[0018]
Although the information rewriting means provided on the intermediate transfer member 51 has been described above, the same means is provided for the photoconductor 1. That is, a layer made of a magnetic material is provided in the sub-scanning direction at any end of the photoconductor 1 to form an information writing area, and a writing head, a detection head, and an erasing head are provided so as to be in contact with the information writing area. Information rewriting means is provided.
FIG. 4 is a sectional view showing the arrangement in the sub-scanning direction of the information rewriting means provided on each of the photosensitive member and the intermediate transfer member, and FIG. 5 is a perspective view showing the arrangement in the main scanning direction. FIG. 6 is a perspective view showing another arrangement of the information rewriting means. The writing head 112 of the photoconductor 1 is arranged on the same line as the main scanning line of the exposure line irradiated from the exposure unit 3, and writes a binary pattern in an information writing area formed at an end of the photoconductor 1. . The written binary pattern reaches the detection head 113 with the rotation of the photoconductor 1 and is detected. The write head 512 of the intermediate transfer body 51 writes the binary pattern in an information writing area provided on the back surface of the belt of the intermediate transfer body 51 so that the detected binary pattern is copied as it is. The detection head 113 and the writing head 512 are positioned on the same main scanning line at a transfer position where the photoconductor 1 and the intermediate transfer body 51 are in contact with each other and the toner image on the surface of the photoconductor 1 is transferred onto the surface of the intermediate transfer body 51. Are located. The binary pattern that has passed through the detection head 113 on the photoconductor 1 is erased by the erasing head 111. On the other hand, the binary pattern on the intermediate transfer body 51 is detected by the detection head 513 and erased by the erasing head 511.
By arranging the information rewriting means of the photoreceptor 1 and the intermediate transfer body 51 closer to the point of the image forming process as described above, the transfer state close to the actual image is reflected on the writing pattern, and the more accurate position Displacement detection and speed difference detection can be performed.
[0019]
In order to arrange the detection head 113 on the photoconductor 1 and the write head 512 on the intermediate transfer body 51 on the same main scanning line at the transfer position, as shown in FIG. It is configured to be longer than the belt width of the transfer body 51 by the information writing area, and the detection head 113 is installed. Further, in this example, the information writing area is formed on the back surface of the intermediate transfer body 51. However, the thickness of the intermediate transfer body 51 greatly fluctuates in one rotation of the belt, and the speed deviation between the belt front surface and the back surface side is reduced. If the value cannot be ignored, it is necessary to set the information writing area on the surface of the intermediate transfer body 51. Therefore, as shown in FIG. 6, a detection head 113 is provided at one end of the photoconductor 1, and at the other end, an information sheet is placed on the intermediate transfer body 51 so as not to overlap the photoconductor 1. A write area is provided, and a write head 512 is provided to write a binary pattern on the intermediate transfer body 51.
On the other hand, in FIG. 4, when the installation position of the detection head 113 and the write head 512 is near the transfer position but not on the same main scanning line, the time required to pass through the detection head 113 and reach the write head 512 is determined by the photosensitive time. It is calculated from the moving speeds of the body 1 and the intermediate transfer body 51, and it is assumed that there is a delay corresponding to that time. By setting the detection head 113 and the write head 512 near the transfer position, rewritable information writing can be performed even when the roll length of the photoconductor 1 and the belt width of the intermediate transfer body 51 are the same. Regions can be provided.
[0020]
The information writing area is provided outside the image forming area for both the photoconductor 1 and the intermediate transfer body 51 as shown in FIGS. With such a configuration, writing and detecting operations can be performed at any time as long as the photoconductor 1 and the intermediate transfer body 51 are rotationally driven. That is, this can be performed over the image formation and non-formation, and the detection operation is performed between the printing operations, and the problem that the user waits is solved. Productivity can also be improved.
In the case where the intermediate transfer member 51 has a structure in which a belt layer and a recording layer 51a are superimposed, an information writing area can be provided on the back surface of the image transfer portion of the intermediate transfer member 51.
[0021]
In particular, when the image forming process is performed, by performing the operation by the information rewriting means in synchronization with the transfer operation of the toner image from the photosensitive member 1 to the intermediate transfer member 51, the information of the positional deviation can be obtained in real time. As a result, it is possible to more accurately detect a position shift and a speed difference, and to perform drive control based on this information.
[0022]
A plurality of information rewriting means provided on the photoconductor 1 and the intermediate transfer body 51 may be provided in each of the main scanning directions. For example, the photoconductor 1 is installed at a front end and a rear end, and each functions independently. Thereby, the inclination in the main scanning direction due to the meandering of the belt of the intermediate transfer body 51 or the misalignment of the photosensitive member 1 can be detected from the detection timing difference between two or more pattern signals. Further, since the plurality of information rewriting units independently perform the writing, detecting, and erasing operations, not only the binary pattern but also the writing of information of a different pattern described later is possible.
[0023]
Next, detection of a speed difference between the photosensitive member 1 and the intermediate transfer member 51 from a detection signal of each information rewriting means will be described. FIG. 7 is a diagram schematically showing a write signal and a detection signal in each information rewriting means. First, a signal pattern at the time of writing by the write head 112 on the photoconductor 1 is a photoconductor write signal 71. This pattern has a fixed period with a binary pulse waveform. The pattern when the detection head 113 on the photoconductor 1 detects this pattern is the photoconductor detection signal 72. The pulse waveform of this signal has a variation in pulse width under the influence of the speed variation due to the eccentricity of the photoconductor 1. The photoconductor detection signal 72 is processed as it is as a write signal through an electric circuit, and a similar pattern is written in an information writing area on the intermediate transfer body 51. That is, the photosensitive member detection signal 72 and the intermediate transfer member write signal 73 have exactly the same pattern. Strictly, a time delay occurs, but can be neglected due to processing as an electric signal.
The pattern written on the intermediate transfer member 51 is detected by the detection head 513, and the detected signal is the intermediate transfer member detection signal 74. The pulse width of this signal changes due to the speed difference between the photosensitive member 1 and the intermediate transfer member 51, and at the same time, the pulse width changes due to the speed fluctuation on the belt side due to the load fluctuation. Further, it changes under the influence of the eccentricity of the driving roller. Therefore, the speed difference can be calculated from the difference between the pulse width T1 of the intermediate transfer member writing signal 73 and the pulse width T2 of the intermediate transfer member detection signal 74. By performing such a calculation of the speed difference for each pulse, it is possible to obtain a variation characteristic of the speed difference with respect to time.
Conventionally, a speed difference was assumed by detecting the set rotation speed of the drive source and the rotation of the drive shaft using a rotary encoder, but at the actual transfer position, the eccentricity of the roller and the fluctuation of the belt thickness It is known that the speed difference fluctuates not only due to the periodic fluctuation, but also due to the influence of the transfer bias, the paper rush load, and the load fluctuation due to the cleaning blade. This is important for misalignment correction. According to the present invention, the speed difference information between the photosensitive member 1 and the intermediate transfer member 51 at the actual transfer position is obtained, so that it is possible to control the rotation speed of the photosensitive member 1 and to correct exposure and writing.
[0024]
Further, the information rewriting means may write multi-value information. By writing information of several bits instead of binary information of 1 or 0 as described above, a waveform signal such as a sine wave is generated instead of a pulse signal. Also, other information such as the number of image sub-scanning lines may be written together. As a result, even if data is damaged due to a writing error or a detection error, it is possible to interpolate from the preceding and following data. Further, by handling a plurality of pieces of information, it is possible to add not only a function as an encoder for detecting a speed difference and a position, but also information such as a manufacturing date and a number of times of use of the belt of the intermediate transfer body 51. Spreads more.
[0025]
Further, the photoreceptor 1 and the intermediate transfer body 51 may use different information recording methods. For example, in an information recording method using a light phase change, writing can be performed in a non-contact manner, so that it is suitable when there is no space for installing an information rewriting means on the photoconductor 1 or the intermediate transfer member 51. Thereby, the width of the layout of the information rewriting means can be increased.
[0026]
FIG. 8 is a schematic configuration diagram of a tandem type image forming apparatus according to the present invention. Image formation in which toner images of respective colors are formed on four photoconductors 1K, 1C, 1Y, and 1M corresponding to four colors of black (K), cyan (C), yellow (Y), and magenta (M). Units 10K, 10C, 10Y, and 10M are provided in parallel. The toner images formed on the photoconductors 1K, 1C, 1Y, and 1M are sequentially transferred to the intermediate transfer body 51 and superimposed in four colors to form a color image. The color image on the intermediate transfer body 51 is transferred to a sheet conveyed by a sheet feeding unit (not shown) at a nip portion between the secondary transfer roller 52 and the transfer belt 53 and is fixed by the fixing unit 7.
The intermediate transfer member 51 is omitted and the transfer belt 53 is in contact with each of the photoconductors 1, and the four color toner images are directly superimposed on the paper conveyed between each of the photoconductors 1 and the transfer belt 53. It is good also as composition to match. In this case, it is assumed that an information rewriting unit included in the intermediate transfer body 51 described later is provided in the transfer belt 53.
[0027]
FIG. 9 is a diagram showing an arrangement of information rewriting means for detecting the amount of color misregistration in a tandem image forming apparatus. A write head 112, a detection head 113, and an erase head 111 are provided on each of the photoconductors 1K, 1C, 1Y, and 1M, respectively. On the belt of the intermediate transfer body 51, write heads 512 are respectively installed at transfer portions with the respective photoconductors 1, and a detection head 513 is provided downstream of the magenta image forming unit 10M serving as the last image forming unit, and further, An erasing head 511 is provided on the downstream side.
The arrangement of the write head 112 of each photoconductor and the positional relationship between the detection head 113 of the photoconductor 1 and the write head 512 of the intermediate transfer body 51 are the same as described above. At the same time as the exposure by the exposure unit 3 of each image forming unit 10, each writing head 112 writes information on each photoconductor 1. It may be a binary pattern or other multi-valued information. The written pattern is detected by each detection head 113, and at the same time, by each writing head 512 on the intermediate transfer member 51, the information is written to the information writing area on the intermediate transfer member 51 by the detection head 113 on the photosensitive member 1. Write exactly the same pattern as the detection pattern.
As shown in FIG. 9B, the information writing areas on the intermediate transfer body 51 are provided separately for each image forming unit 10, and the detection head 513 detects the lines for detecting the plurality of patterns. It is a detection head. Thus, the cueing (vertical registration) of each image can be adjusted based on the time difference between the patterns of the image forming units detected by the detection head 513. In addition, a pattern can be detected even in an intermediate portion of an image, and a color shift amount can be detected from a time difference.
[0028]
In the embodiment shown in FIG. 9, it is preferable that the arrangement of the detection head 513 on the intermediate transfer member 51 be an integral multiple of the circumference of the driving roller 54. In a tandem type image forming apparatus, the distance between the image forming units is set to an integral multiple of the circumference of the drive roller of the intermediate transfer belt (the circumference of the intermediate transfer belt conveyed by one rotation of the drive roller). It has been proposed that the effect of speed fluctuations that occur in one rotation of the driving roller due to eccentricity of the roller can be reduced (Japanese Patent Application Laid-Open No. 2001-125339). Therefore, in FIG. 9, if the intervals L1, L2, and L3 of the image forming units 10K, 10C, 10Y, and 10M are arranged so as to be an integral multiple of the circumference of the driving roller 54, the image forming unit 10M is detected. The intervals between the heads 513 are also arranged to be an integral multiple. Thus, the color shift can be detected more accurately without being affected by the eccentricity of the drive roller 54 and the like.
[0029]
The method of detecting the speed difference between the photosensitive member 1 and the intermediate transfer member 51 from the detection signal of each information rewriting means and controlling the rotation speed of each of the photosensitive members 1K, 1C, 1Y, and 1M is shown in FIG. It can be similar to that described.
[0030]
FIG. 10 is a diagram illustrating another embodiment of the tandem type image forming apparatus. The information rewriting means arranged on the photoconductors 1K, 1C, 1Y, and 1M is the same as in FIG. On the other hand, in the intermediate transfer body 51, a write head 512K is disposed at a transfer portion with the photoreceptor 1K, and detection heads 513C, 513Y, and 513M are disposed at a transfer portion with the photoreceptors 1C, 1Y, and 1M. An erase head 511 is arranged downstream of the forming unit 10M. In the information writing area on the belt of the intermediate transfer body 51, as shown in FIG. 10B, only the area for the black image forming unit 10K is formed. The pattern detected by the detection head 113K of the photoconductor 1K is written in the information writing area of the intermediate transfer body 51 by the writing head 512K. The write signal may be a binary pattern or other multi-valued information. In the transfer unit of the photoconductor 1C, a detection signal of the pattern written by the write head 112C of the photoconductor 1C by the detection head 113C and a detection of the pattern written by the write head 512K on the intermediate transfer body 51 by the detection head 513C. By comparing the signal with the signal, the amount of color misregistration based on black can be detected. The same applies to yellow and magenta.
[0031]
In the embodiment shown in FIG. 10, a method for controlling the rotation speed of each photoconductor will be described. FIG. 11 is a diagram for explaining detection of a speed difference between the photosensitive member 1 and the intermediate transfer member 51 by writing multi-value information and control of the rotation speed of the photosensitive member 1. The write waveform of the photoconductor 1K by the write head 112K is S1. A similar waveform S2 is written by the write heads 112C, 112Y, and 112M at the same timing as when a toner image is superimposed on the intermediate transfer body 51. The waveform data written on the intermediate transfer member 51 in the same process as described above is obtained when the speed difference between the photosensitive member 1K and the intermediate transfer member 51, for example, when the speed of the intermediate transfer member 51 is high, as shown in S3. The waveform period becomes longer. This waveform also includes the effect of speed fluctuations during transfer. The waveform S3 on the intermediate transfer member 51 is detected by the detection head 512C. At the same time, the detection head 113C detects the waveform S2 on the photoconductor 1C. The rotation speed of the photoconductor 1C is controlled so that the values of the waveform data of the waveform S3 and the waveform S2 (the value in the Y direction indicated by the waveform S4) match. The same applies to the photoconductors 1Y and 1M. Each photoconductor is configured to be driven independently, and performs speed control according to each. By such control, the position of each color can be adjusted based on black. Note that even if the write signal is a binary pattern, the same control can be performed by eliminating the time difference between the pulse intervals or by making the number of pulses counted the same.
[0032]
【The invention's effect】
As described above, according to the present invention, conventionally, there has been no problem due to toner scattering of an image pattern made of toner, which has been a problem in detecting a color shift amount of a color image. On the other hand, with the information rewriting means using a more reliable information recording method, the positioning of each toner image can be performed with high accuracy. Thus, an image forming apparatus capable of outputting a high-definition image can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main part of an image forming apparatus according to the present invention.
FIG. 2 is a diagram schematically showing a magnetic recording type information rewriting means.
FIG. 3 is a diagram showing another magnetic recording type information rewriting means.
FIG. 4 is a cross-sectional view showing an arrangement in a sub-scanning direction of information rewriting means provided on each of a photoconductor and an intermediate transfer member.
FIG. 5 is a perspective view showing an arrangement in the main scanning direction of information rewriting means provided on each of a photoconductor and an intermediate transfer member.
FIG. 6 is a perspective view showing another arrangement of the information rewriting means.
FIG. 7 is a diagram schematically showing a write signal and a detection signal in each information rewriting means.
FIG. 8 is a schematic configuration diagram of a tandem image forming apparatus according to the present invention.
FIG. 9 is a diagram showing an arrangement of information rewriting means for detecting a color shift amount in the tandem type image forming apparatus.
FIG. 10 is a diagram illustrating another embodiment of a tandem-type image forming apparatus.
FIG. 11 is a view for explaining detection of a speed difference between a photoconductor and an intermediate transfer body by writing multi-value information and control of a photoconductor rotation speed.
[Explanation of symbols]
1 Photoconductor (image carrier)
111 Erasing means
112 Writing means
113 detection means
2 Charging means
3 Exposure means
4 Developing means
5 transfer means
51 Intermediate transfer member
511 Erasing means
512 Writing means
513 detection means
54 Drive roller

Claims (11)

An image carrier for carrying a latent image,
Exposure means for writing a latent image on the image carrier,
Developing means for supplying a toner to the latent image on the image carrier to visualize the latent image;
Transfer means for transferring the visible image of the image carrier to a recording medium,
The transfer unit includes a transfer member including a belt-shaped member,
The image carrier and the transfer member have an information writing area that can be rewritten in the sub-scanning direction on each surface,
An image forming apparatus, comprising: an information rewriting unit including a writing unit for writing information in each information writing area, a detection unit for detecting information, and an erasing unit for erasing information. The image forming apparatus according to claim 1,
The writing unit included in the image carrier is disposed on the same line as a main scanning line of exposure light that the exposure unit irradiates on the surface of the image carrier,
The detection unit provided in the image carrier and the writing unit provided in the transfer member are arranged on the same main scanning line at a transfer position between the image carrier and the transfer member. Image forming device. The image forming apparatus according to claim 1, wherein
The image forming apparatus according to claim 1, wherein the information writing area is arranged outside the image forming area. The image forming apparatus according to claim 1, wherein
The operation of the information rewriting means is executed at the time of image formation. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the image carrier and the transfer member each include a plurality of the information rewriting units in a main scanning direction. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein a speed difference between the image carrier and the transfer member is detected based on a detection signal of a detection unit included in the image carrier and a detection unit of the transfer member. The image forming apparatus according to claim 6,
The image forming apparatus controls the rotation speed of the image carrier by detecting a speed difference between the image carrier and the transfer member by the detection unit. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein information recorded in the information writing area provided on the image carrier and the transfer member is multi-valued information. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the image carrier and the transfer member include information rewriting means using different information recording methods. A plurality of image carriers for carrying latent images,
Exposure means for writing a latent image on each of the image carriers, developing means for supplying toner to the latent image on the image carrier to visualize the latent image, and transfer for transferring the visible image of the image carrier to a recording medium And an image forming apparatus comprising:
The transfer unit includes a transfer member including a belt-shaped member,
The plurality of image carriers and the transfer member each have an information writing area that can be rewritten in the sub-scanning direction on each surface,
Each image carrier includes a writing unit that writes information in each information writing area, a detection unit that detects information, and an information rewriting unit that includes an erasing unit that erases information.
The image forming apparatus according to claim 1, wherein the transfer member includes an information rewriting unit including a writing unit that writes information in the information writing area, a detection unit that detects the information, and an erasing unit that erases the information. The image forming apparatus according to claim 10,
The image forming apparatus according to claim 1, wherein the transfer member is disposed at a position where the detection unit is an integral multiple of a circumference of a driving roller of the transfer member.

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