JP2004198630A - Method and device for transferring a plurality of toner images and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce registration shift when a plurality of toner images are transferred to a sheet-like recording medium from latent image carriers that are different from one another. <P>SOLUTION: The transfer device forms mark images for transfer positioning, as toner images, onto the corresponding latent image carriers 91B to 91C. The device transfers the mark images PTB on a transfer medium 9041 which is common to them. The device then optically reads and detects the mutual positional relationships between the mark images with a detecting means SN. Based upon the result by the detecting means, the device controls the linear velocities of the latent image carriers 91B to 91C with a control means, thus performing transfer after reducing registration shift between the toner images to be transferred. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and apparatus for transferring a plurality of toner images and an image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art An image forming apparatus based on an optical writing method using the principle of electrophotography is conventionally known as a digital copying apparatus, an optical printer, an optical plotter, a facsimile apparatus, or the like. In these image forming apparatuses, “colorization of formed images” is progressing, but there is also a strong demand for image forming speed, and so-called “tandem type image forming” capable of forming color images at about the same speed as monochrome image forming. The realization of a "device" is intended.
[0003]
In a tandem-type image forming apparatus, an electrostatic latent image is formed on a plurality of latent image carriers by optical writing, developed with a different color toner for each electrostatic latent image, and a different color image is formed for each latent image carrier. A toner image is formed, and the plurality of toner images are transferred to a common sheet-shaped recording medium so as to overlap each other, thereby forming a color image or a multicolor image.
[0004]
For this reason, in the tandem-type image forming apparatus, the quality of the overlapping of a plurality of toner images transferred to the same sheet-shaped recording medium greatly affects the image quality of the formed image. In order to accurately perform such overlapping of the toner images, it is a major issue how to accurately perform so-called “registration” in which the leading ends of the toner images are mutually performed.
[0005]
In a tandem-type image forming apparatus, an optical system for optical writing, a latent image carrier, and a transfer unit for transferring a toner image are separate from each other. There are many factors that cause "shift" between toner images, such as the distance to the toner image. Such a shift between a plurality of toner images is called “registration shift”.
[0006]
Further, even if the adjustment of the apparatus is completely performed and the resist deviation can be reduced to zero, a change in the optical characteristics of the resin lens due to a temperature change and an expansion and contraction of the latent image carrier are inevitable. Causes a "registration shift between toner images".
[0007]
As a method of reducing the "registration deviation", conventionally, a "register registration mark" is written as an electrostatic latent image on each latent image carrier, and a toner image obtained by visualizing the electrostatic latent image is transferred onto a transfer belt. Then, the positional relationship between the mark images is optically read, and the start timing of optical writing is controlled based on the read result (Patent Document 1 etc.).
In this case, an optical writing means for deflecting a light beam by the rotating polygon mirror is provided for each latent image carrier, and the phase of rotation of the rotating polygon mirror corresponding to each latent image carrier is controlled, so that each latent image carrier is controlled. It has also been proposed to control the start timing of optical writing with high accuracy and to perform resist alignment with high accuracy (Japanese Patent Application Laid-Open No. H10-163,837). However, since the rotation of the rotary polygon mirror is extremely fast, it is not easy to control the phase of the rotation, and an expensive control device is required, which tends to increase the cost.
[0008]
On the other hand, a tandem type image forming apparatus has been proposed in which a rotating polygon mirror is used in common for a light beam that optically scans a plurality of latent image carriers (Patent Document 3 and the like). Cannot control the phase of rotation of the rotary polygon mirror in correspondence with each latent image carrier, and there is a limit to the effect of reducing registration.
[0009]
In addition, a scale for detecting the linear velocity is formed on the intermediate transfer belt or the sheet transport belt, and the scale of the intermediate transfer belt or the sheet transport belt is detected based on the linear velocity detected by the scale detecting means. It is known from Japanese Patent Application Laid-Open Publication No. HEI 9-163556 to control the rotation drive.
[0010]
[Patent Document 1]
JP-A-8-248721
[Patent Document 2]
JP-A-10-138556
[Patent Document 3]
JP-A-10-3048
[Patent Document 4]
JP-A-8-10371
[0011]
[Problems to be solved by the invention]
The present invention provides a novel multi-toner image transfer method and an apparatus for performing the method, which can effectively reduce registration deviation in a tandem image forming apparatus, and an image forming apparatus including the above-described multi-toner image transfer apparatus. Realization is the task.
[0012]
[Means for Solving the Problems]
The method for transferring a plurality of toner images according to the present invention provides a method for visualizing electrostatic latent images formed by optical writing on a plurality of rotationally driven latent image carriers with toners of different colors for different latent image carriers. A plurality of toner images having different colors from each other are obtained, and the plurality of toner images are superimposed and transferred from each latent image carrier onto the same sheet-shaped recording medium to form a multi-color image or a color image. A method of transferring a plurality of toner images onto a sheet-shaped recording medium in the image forming method.
[0013]
Each of the “a plurality of rotationally driven latent image carriers” is formed in a drum shape or an endless belt shape. The latent image carrier is photoconductive, and after being uniformly charged, forms an electrostatic latent image by optical writing.
The `` optical writing means '' that performs optical writing controls each light emitting element of the light source device in which minute light emitting elements are arranged in an array in accordance with image signals, and the image of the light emitting element on the latent image carrier by a lens array or the like. An optical writing method by forming an image or an optical scanning method described later may be used.
[0014]
The “sheet-shaped recording medium” is a sheet-shaped medium that ultimately carries an image, such as a normal transfer paper or an OHP sheet (a plastic sheet for an overhead projector).
The “multi-color image” is, for example, a red / black two-color image or a multi-color image.
[0015]
The method for transferring a plurality of toner images according to the first aspect has the following features.
That is, a mark image for transfer position alignment is formed as a toner image on each latent image carrier, these mark images are transferred onto a common transfer medium, and the positional relationship between the mark images is optically read by a detecting means. To detect.
Then, based on the detection result by the detection unit, the “linear velocity of the plurality of latent image carriers (moving speed of the photosensitive surface due to the rotation of the latent image carrier)” is controlled by the control unit, and the “linear speed between the toner images transferred” is controlled. The transfer is performed with the “registration shift” reduced.
[0016]
The “mark image” is written on a uniformly charged latent image carrier by an optical writing unit, and is visualized with toner of a color corresponding to the latent image carrier.
[0017]
2. The method for transferring a plurality of toner images according to claim 1, further comprising the steps of: "using an intermediate transfer belt, using the intermediate transfer belt as a common transfer medium, transferring a mark image for transfer position alignment on each latent image carrier, and The toner images of different colors formed on a plurality of photoconductors are primarily transferred onto an intermediate transfer belt to obtain a multi-color image or a color image on the intermediate transfer belt. (Second transfer of a multi-color image or a color image from an intermediate transfer belt onto a sheet-shaped recording medium).
[0018]
2. The method for transferring a plurality of toner images according to claim 1, further comprising the step of using a sheet conveying belt for conveying a sheet-shaped recording medium, and using the sheet conveying belt as a common transfer medium, a mark for transfer position alignment on each latent image carrier. The images are transferred, optically read and detected by the detecting means, and the toner images having different colors formed on the plurality of latent image carriers are mutually transferred onto a sheet-shaped recording medium sucked and conveyed by a sheet conveying belt. (Overlap and transfer to form a multi-color image or a color image) ".
[0019]
In the method for transferring a plurality of toner images according to any one of claims 1 to 4, "the linear velocity of the plurality of latent image carriers is controlled uniformly by the control means based on the detection result by the detection means". (Claim 4).
[0020]
The method for transferring a plurality of toner images according to any one of claims 1 to 3, further comprising the step of: "controlling at least one linear velocity of the plurality of latent image carriers based on a detection result by the detecting means, (Independent of the linear velocity of the latent image carrier) (claim 5). In this case, it is possible to "control the linear velocities of the plurality of latent image carriers independently of each other by the control means" based on the detection result by the detection means (claim 6).
[0021]
The method for transferring a multi-toner image according to any one of claims 1 to 6 can “reduce the registration error between the transferred toner images and control the start timing of the optical writing”. Claim 7).
[0022]
The multi-toner image transfer device according to the present invention is configured such that “each electrostatic latent image formed by optical writing on a plurality of rotationally driven latent image carriers is visualized with toner of a different color for each different latent image carrier. A plurality of toner images having different colors from each other are obtained, and the plurality of toner images are superimposed and transferred from each latent image carrier onto the same sheet-shaped recording medium to form a multi-color image or a color image. An apparatus for transferring a plurality of toner images to a sheet-shaped recording medium in an image forming method, comprising a detecting unit, a control amount generating unit, and a controlling unit.
[0023]
The “detection unit” optically reads and detects “each mark image for transfer position alignment” formed on each latent image carrier by optical writing, visualized as a toner image, and transferred onto a common transfer medium. Means. As such a detecting means, various means conventionally used for reading an encoder can be appropriately used.
[0024]
The “control amount generating unit” is a unit that generates a control amount for controlling the linear velocities of the plurality of latent image carriers based on the positional relationship between the mark images detected by the detecting unit. The control amount generating means generates a "control amount for reducing registration deviation between the transferred toner images".
[0025]
The “control means” is means for controlling the rotational driving of the plurality of latent image carriers based on the control amount generated by the control amount generating means.
As the control amount generating means and the control means, a computer or a CPU programmed with a dedicated arithmetic program can be used.
[0026]
9. The multi-toner image transfer apparatus according to claim 8, further comprising: an intermediate transfer belt, and using the intermediate transfer belt as a common transfer medium, transferring a mark image for transfer position alignment on each latent image carrier and detecting the transfer image. Primary transfer means for optically reading and detecting the toner image, and primary-transferring toner images of different colors formed on a plurality of photoconductors to an intermediate transfer belt to obtain a multicolor image or a color image; Alternatively, there is provided a secondary transfer means for secondary-transferring a color image from an intermediate transfer belt onto a sheet-shaped recording medium.
Transfer devices using a primary transfer unit and a secondary transfer unit are already widely known, and these known units can be appropriately used.
[0027]
The multi-toner image transfer device according to claim 8, further comprising a sheet transport belt for transporting the sheet-shaped recording medium, and using the sheet transport belt as a common transfer medium for aligning a transfer position on each latent image carrier. The mark image is transferred and optically read and detected by the detection means, and the toner images of different colors formed on the plurality of photoconductors are superimposed on a sheet-shaped recording medium sucked and conveyed by a sheet conveying belt. (Transfer means for transferring the image).
Various types of transfer devices using a sheet conveying belt as a transfer medium are known, and such a known device may be appropriately used.
[0028]
10. The multi-toner image transfer device according to claim 9, wherein a scale for detecting the linear velocity is formed on the intermediate transfer belt, and a scale detecting means for detecting the scale, and a linear velocity for detecting the scale. And an intermediate transfer belt drive control means for controlling the rotation drive of the intermediate transfer belt based on the above-mentioned configuration.
[0029]
11. The multi-toner image transfer device according to claim 10, wherein a scale for detecting the linear velocity is formed on the sheet conveying belt, and scale detecting means for detecting the scale, and linear velocity detected by the scale detecting means. Based on the above, there is provided a sheet conveying belt drive control means for controlling the rotational driving of the sheet conveying belt.
[0030]
As described above, a transfer device that forms a scale on an intermediate transfer belt or the like, detects the linear velocity of the scale, and controls the linear velocity of the belt with drive control means is also known from Patent Document 4 or the like. For these, known methods can be appropriately used.
[0031]
The multi-toner image transfer device according to any one of claims 8 to 12, wherein the control amount generation unit determines the linear velocity of the plurality of latent image carriers based on a positional relationship between the mark images detected by the detection unit. Is generated uniformly, and the control unit uniformly controls the linear velocities of the plurality of latent image carriers based on the control amount generated by the control amount generation unit. " Claim 13).
[0032]
The multi-toner image transfer device according to any one of claims 8 to 12, wherein the control amount generation unit is configured to output the control amount generation unit based on a positional relationship between the mark images detected by the detection unit. A control amount for controlling at least one linear velocity independently of the linear velocity of another latent image carrier is generated, and the control means controls at least one linear velocity of the plurality of latent image carriers to another latent image carrier. In this case, the control amount generating means generates a control amount for controlling the linear speed of each of the latent image carriers, wherein the control amount is controlled independently of the linear speed of the image carrier. The controller may control the linear velocities of the plurality of latent image carriers independently of each other based on the control amount generated by the control amount generator (claim 15).
[0033]
The image forming apparatus according to the present invention is configured such that “an electrostatic latent image is formed on a plurality of rotationally driven latent image carriers by optical writing, and each formed electrostatic latent image is formed in a different color for each different latent image carrier. Visualizing with a toner to obtain a plurality of toner images having different colors from each other, transferring the plurality of toner images from each latent image carrier onto the same sheet-like recording medium in a superimposed manner, 16. An image forming apparatus for forming a color image, comprising: a transfer unit configured to transfer a plurality of toner images having different colors from each latent image carrier to a sheet-shaped recording medium. (16) A multi-toner image transfer device according to (16).
[0034]
17. An image forming apparatus according to claim 16, wherein the number of latent image carriers is four, a black toner image and toner images of the other three colors are formed on these four latent image carriers, respectively. The linear velocity of a latent image carrier on which a black toner image is formed is controlled independently of the linear velocities of other latent image carriers. Claim 17).
[0035]
That is, in this case, the linear velocity of the latent image carrier on which the black toner image is formed is controlled independently of the other latent image carriers, and the linear velocities of the other latent image carriers are “uniform or independent of each other. Is controlled.
[0036]
The "optical writing means for writing an electrostatic latent image on each latent image carrier" in the image forming apparatus according to claim 16 or 17 can be of an optical scanning type that deflects a light beam by a rotating mirror. Item 18). The rotating mirror is a rotating single-sided mirror, a rotating two-sided mirror, or a rotating polygonal mirror.
[0037]
In the image forming apparatus according to the eighteenth aspect, the “rotating mirror that deflects the light beam” can be commonly used to deflect the light beam that optically scans a plurality of latent image carriers. The image forming apparatus according to any one of claims 16 to 19, wherein "the timing of starting the optical writing by the optical writing means for writing the electrostatic latent image on each latent image carrier is controlled for each latent image carrier. Possible ”(claim 20).
[0038]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram for describing an embodiment of an image forming apparatus.
[0039]
The image forming apparatus 900 shown in FIG. 1A is a tandem type color image forming apparatus. The color document is read by the reading unit 901 after being separated into red, green, and blue, and based on the read information, the color originals for black (B), yellow (Y), magenta (M), and cyan (C) are read. Image data is generated.
[0040]
These image data are supplied to the image writing stations 903B, 903Y, 903M, and 903C for optical writing by the optical writing device 902. Since the image forming stations 903B to 903C are structurally the same, the image forming station 903B will be described as an example.
[0041]
As shown in FIG. 1B, the image forming station 903B includes a charging charger 92, a developing device 93, and a transfer charger around a photosensitive drum 91B as a “latent image carrier” that is driven to rotate counterclockwise. 94 and a cleaning device 95 are provided.
[0042]
As shown in FIG. 1A, the intermediate transfer belt 9041 of the primary transfer means 904 runs between the photosensitive drum 91B and the transfer charger 94. The photoconductor drum 91B is uniformly charged by the charging charger 92 while rotating counterclockwise, and B image data corresponding to a black image is written by the laser beam LBB to form a B latent image. The B latent image is reversely developed by the developing device 93 to become a B toner image of black toner, and this B toner image is transferred to the intermediate transfer belt 9041 by the transfer charger 94. After the transfer of the toner image, the photosensitive drum 91 is cleaned by the cleaning device 95.
[0043]
Similarly, in the image forming stations 903Y, 903M, and 903C, Y (yellow), M (magenta), and C (cyan) color toner images are formed, and these Y, M, and C toner images are The image is transferred onto “9041” so as to “overlap with the B toner image”. The color image of the B, Y, M, and C toner images formed on the intermediate transfer belt 9041 in this manner is transferred onto a transfer sheet S as a “sheet-shaped recording medium”.
[0044]
The transfer paper S is fed from a cassette 906 at the bottom of the image forming apparatus main body, or is manually distributed from a manual feed unit 907, and is transferred by a registration roller 909 between the transfer unit, that is, the intermediate transfer belt 9041 and the secondary transfer belt 905. The color image is sent to the contact portion with a timing to move the color image, and the color image is transferred by the action of a transfer bias applied to the secondary transfer belt 905 from a bias applying unit (not shown). The secondary transfer belt 905 and the bias applying unit (not shown) constitute “secondary transfer unit”.
[0045]
The transfer paper S on which the color image has been transferred is conveyed by a secondary transfer belt 905, is discharged by a charge eliminator (not shown), is separated from the secondary transfer belt 905, and the color image is fixed by a fixing device 910. And discharged by the discharge roller 912 out of the apparatus.
[0046]
In the case of the “double-sided image forming mode” in which images are formed on both sides of the transfer sheet S, the transfer path of the transfer sheet S on which the color image is fixed on one side is switched by the switching claw 915, and the transfer roller 911 and the guide (not shown) are switched. To the reversing unit 913, and turn over in the reversing unit 913, stack the sheets on the stacker 914 with the “surface on which the color image is formed facing upward”, convey again to the position of the registration roller 909, and do the same as above. To transfer the color image to the back side. Thereafter, the color image on the back surface is fixed by the fixing device 910, conveyed by the conveyance roller 911, and discharged out of the device by the discharge roller 912.
[0047]
The intermediate transfer belt 9041 may be formed, for example, on a “base layer of a low-elongation fluororesin” or a “base layer of a high-elongation rubber material on which a non-elongation material such as canvas is provided” with a fluorine-based rubber or acrylonitrile-butadiene. An elastic layer made of polymer rubber or the like may be provided, and the surface thereof may be coated with a fluorine-based resin or the like as a release layer.
[0048]
FIG. 2 is a diagram for explaining another embodiment of the image forming apparatus. In order to avoid complication, the same symbols as those in FIG. For the portions denoted by the same reference numerals as those in FIG. 1, the above description based on FIG. 1 is cited.
[0049]
The image forming apparatus shown in FIG. 2A is also a tandem-type color image forming apparatus, and a color document is read by being separated into red, green, and blue by a reading unit 901, and B, Image data for each of the colors Y, M, and C is generated, and the image data is subjected to optical writing by the optical writing device 902 at the image forming stations 903B, 903Y, 903M, and 903C.
[0050]
FIG. 2B illustrates a main mechanical part of the transfer device 920. As shown in the figure, the upper surface of the sheet conveying belt 9200 is stretched so as to contact the photosensitive drums 91B, 91Y, 91M, and 91C used in each image forming station from below. The sheet conveyance belt 9200 is wound around rollers 9201, 9202, 9203, 9205, and 9206, and is driven to rotate counterclockwise by a driving roller 903. The roller 9204 is a “tension roller” that applies necessary belt tension to the sheet conveying belt 9200 and increases the winding angle of the sheet conveying belt 9200 around the driving roller 9203 so that the driving force of the driving roller 9203 ensures that the sheet is conveyed. It is transmitted to the belt 9200.
[0051]
Transfer rollers 9B, 9Y, 9M, and 9C are provided on the inner peripheral side of the sheet conveying belt 9200 so as to press the corresponding photosensitive drums 91B, 91Y, 91M, and 91C via the sheet conveying belt 9200, The pressing rollers RB, RY, RM, and RC provided in the vicinity of these transfer rollers apply a force to push the sheet conveying belt 9200 upward, and the sheet conveying belt 9200 applies a “desired width” to each photosensitive drum. Nip portion ".
[0052]
A transfer bias is applied to the transfer rollers 9B, 9Y, 9M, and 9C from bias power supplies 90B, 90Y, 90M, and 90C.
[0053]
When the transfer of the toner image is performed, the transfer sheet S, which is a sheet-shaped recording medium, is fed to a sheet conveying belt by a registration roller (not shown).
The fed transfer paper S is charged by the charging roller 95 while being squeezed and conveyed by the charging roller 95 and the sheet conveyance belt 9200, and is conveyed while being electrostatically adhered to the outer peripheral surface of the sheet conveyance belt 9200. The C toner image, the M toner image, the Y toner image, and the B toner image are sequentially transferred from the body drums 91C, 91M, 91Y, and 91B. By this transfer, a color image is formed on the transfer paper S.
[0054]
After the transfer of the toner images of the respective colors, the transfer paper S is discharged by a discharging unit (not shown), separated from the sheet conveying belt 9200, sent to a fixing device 910, fixed by the fixing device 910, and discharged out of the device. You.
[0055]
The transfer rollers 9Y, 9M, and 9C and the pressing rollers RY, RM, and RC are integrated with each other, and can be retracted from the photosensitive drums 91Y, 91M, and 91C by a mechanism (not shown). In the "image forming mode for forming a monochrome image by color", only the transfer roller 9B operates.
[0056]
Conversely, when performing the "image forming mode in which a black image is not formed", the transfer rollers 9Y, 9M, and 9C and the pressing rollers RY, RM, and RC are set in an operable state, and the transfer roller 9B and the pressing roller RB are moved by a mechanism (not shown). Then, the photosensitive drum 91B is retracted from the photosensitive drum 91B side to make it inoperative.
[0057]
Hereinafter, transfer of a plurality of toner images will be described.
FIG. 3 is a diagram for explaining an embodiment in which the transfer method according to the first, second, and fourth aspects is applied to the image forming apparatus shown in FIG.
[0058]
In this embodiment, the four photosensitive drums 91B, 91Y, 91M, and 91C are driven by a "common motor" and a gear mechanism (not shown) so that the linear velocities on the peripheral surfaces become equal to each other.
[0059]
In order to perform registration, mark images PTY, PTC, PTM, and PTB for transfer position alignment as shown in FIG. 3B are formed on each of the latent image carriers 91Y, 91C, 91M, and 91B by optical writing. And development) to form a toner image, transfer these mark images PTY, PTC, PTM, and PTB onto an intermediate transfer belt 9041 that is a “common transfer medium”, and detect the positional relationship between these mark images. To optically read and detect.
[0060]
In the mark images PTY, PTC, PTM, and PTB in FIG. 3B, each dashed mark is an “ideal position where there is no shift in the registration position”, and each solid line mark is an “actually read position”. Is shown. A plurality of mark images are formed along the running direction of the intermediate transfer belt 9041, and are read by the reading means SN.
[0061]
The read mark image is processed by an unillustrated “calculating section of control means”, and a read time difference between the mark PTB corresponding to the B toner image and another mark: PTY-PTB, PTC-PTB, PTM-PTB is calculated. Using these, an “average deviation from the ideal value” is calculated.
[0062]
The “average value” thus calculated and the “deviation from the target value” are reflected on the driving speed of the “motor” that drives the photosensitive drums, and the control means controls the photosensitive drums 91B to 91C. Is uniformly controlled to reduce resist deviation. Even in this case, “registration deviation from the average value” occurs for each photosensitive drum, but the registration deviation is smaller than when no correction is performed.
[0063]
Supplementing the description slightly, the position indicated by arrows AB and AY in FIG. 3C is “the writing position for the photosensitive drums 91B and 91Y”, and the position indicated by arrows TB and TY is “the middle of the B toner image and the Y toner image”. Transfer position on transfer belt 9041 ".
[0064]
Here, let us consider a case where the cause of the registration error is “mismatch of the distance from the writing position to the transfer position” in the photosensitive drums 91B and 91Y. That is, the distance from the writing position AB to the transfer position TB on the photosensitive drum 91B is “D”, and the distance from the writing position AY to the transfer position TY on the photosensitive drum 91Y is “D + ΔD”.
[0065]
It is assumed that the photosensitive drums 91B and 91Y are both driven at the same linear speed. If this linear speed is set to “V”, the written B latent image is changed to a B toner image on the photosensitive drum 91B. The time required to reach the transfer position TB is “D / V”, and the time required for the written Y latent image to become the Y toner image and reach the transfer position TY is “(D + ΔD) / V ", that is," (D / V) (1 + ΔD / D) ".
[0066]
At this time, the difference between these times: (D / V) · (1 + ΔD / D) − (D / V) = (D / V) · (ΔD / D)
"Resist shift" corresponding to the above.
[0067]
In this state, assuming that the linear velocities of the photosensitive drums 91B and 91Y are “V + ΔV”, the time required for the written B latent image to become the B toner image and reach the transfer position TB on the photosensitive drum 91B is “D”. / (V + ΔV) ”, and the time for the written Y latent image to reach the transfer position TY as a Y toner image on the photosensitive drum 91Y is“ (D + ΔD) / (V + ΔV) ”.
[0068]
Since the above time: D / (V + ΔV) is D / {V (1 + ΔV / V)}, if the parenthesis of the denominator is expanded to take the first-order term, (D / V) (1−ΔV / V) V).
[0069]
Similarly, since the time: (D + ΔD) / (V + ΔV) becomes {D (1 + ΔD / D)} / {V (1 + ΔV / V)}, this is modified in the same manner as above to obtain the following equation.
[0070]
(D + ΔD) / (V + ΔV) ≒ (D / V) (1 + ΔD / D) (1-ΔV / V)
= (D / V) {1 + ΔD / D−ΔV / V− (ΔV / V) · (ΔD / D)}
Therefore, the difference from time: (D / V) (1−ΔV / V) is
(D / V) {ΔD / D− (ΔV / V) · (ΔD / D)}
= (D / V) (ΔD / D) {1- (ΔV / V)}
It becomes.
[0071]
Assuming that (D / V) · (ΔD / D) = TR “time before changing the linear velocity by ΔV”, the time when the linear velocity is changed by ΔV is:
TR {1- (ΔV / V)}
Therefore, if ΔV> 0, the time corresponding to the resist shift can be reduced, and the resist shift itself can be reduced.
[0072]
That is, in the method for transferring a plurality of toner images described with reference to FIG. 3, each electrostatic latent image formed by optical writing is transferred to a plurality of latent image carriers 91B to 91C that are driven to rotate. Each toner image is visualized with a toner of a different color to obtain a plurality of toner images having different colors, and the plurality of toner images are transferred from each latent image carrier onto the same sheet-shaped recording medium in a superimposed manner. A method of transferring a plurality of toner images to a sheet-shaped recording medium in a multi-color image or an image forming method of forming a color image, wherein mark images PTB, PTY, PTM, and PTC for transfer position alignment are transferred to respective latent images. A toner image is formed on a carrier, these mark images are transferred onto a common transfer medium 9041, and the positional relationship between the mark images is optically read and detected by a detecting means SN. A plurality of toner image transfer methods for controlling the linear velocities of the plurality of latent image carriers 91 </ b> B to 91 </ b> C based on the detection result by the control unit to reduce the registration deviation between the transferred toner images and perform the transfer. 1).
[0073]
Further, using the intermediate transfer belt 9041, the mark images PTB to PTC for transfer position alignment on each latent image carrier are transferred using the intermediate transfer belt 9041 as a common transfer medium, and are optically read and detected by the detection means SN. Then, the toner images of different colors formed on the plurality of latent image carriers are primarily transferred to the intermediate transfer belt 9041 to obtain a multi-color image or a color image on the intermediate transfer belt. Is transferred to the sheet-shaped recording medium S from the intermediate transfer belt 9041 in a multi-toner image transfer method (Claim 2), and a plurality of latent image carriers 91B to 91C are detected based on the detection result by the detection means SN. Is a method for transferring a plurality of toner images, in which the linear velocity is uniformly controlled by a control means.
[0074]
It is clear that the above-described embodiment can be easily diverted even when the “transfer device 920 using the sheet conveying belt 9200” shown in FIG. 2 is used instead of the intermediate transfer belt 9041.
[0075]
That is, a mark image PTB to PTC for transfer position alignment on each latent image carrier is transferred by using a sheet conveyance belt 9200 for conveying the sheet-shaped recording medium S and using the sheet conveyance belt 9200 as a common transfer medium. The toner images having different colors formed on the plurality of latent image carriers 91 </ b> B to 91 </ b> C are optically read and detected by the detection unit, and are superimposed on the sheet-shaped recording medium S suction-conveyed by the sheet conveyance belt 9200. The images can be transferred together to form a multi-color image or a color image.
[0076]
FIG. 4 is a diagram for explaining a case where the method according to the first, second, fifth, and sixth aspects is applied to a multiple toner image transfer apparatus used in the image forming apparatus shown in FIG. In this embodiment, as shown in FIG. 4A, the photosensitive drums 91B, 91Y, 91M, and 91C, which are latent image carriers, are separately driven by a motor B, a motor Y, a motor M, and a motor C, respectively. Driven.
[0077]
As in the case of the embodiment shown in FIG. 3, mark images PTB to PTC as shown in FIG. 3B are formed on each photosensitive drum (by optical writing by laser beams LBB, LBY, LBM, LBC). The transfer is performed using the intermediate transfer belt 9041 as a common transfer medium, and is optically read and detected by the detection means SN.
[0078]
As shown in FIG. 4B, information on the mark images PTB to PTC read by the image mark reading sensor SN, which is a “reading unit”, is stored in each color error calculation unit 12 that also serves as a “control amount generating unit and a control unit”. Is processed.
[0079]
Each color error calculation unit 12 generates a separate control amount for controlling the linear velocity of each of the latent image carriers 91B to 91C as a “control amount generating unit”, and generates a plurality of control amounts based on the generated control amount as a “control unit”. Of the latent image carriers 91B to 91C are controlled independently of each other.
[0080]
That is, the generated "control amount" is input to the motor Y driver to the motor B driver, and independently controls the linear velocity of the motor Y to the motor B.
[0081]
The control amount for the linear velocity of each photosensitive drum is generated as follows.
As in the case of the embodiment shown in FIG. 3, the mark images PTY, PTC, PTM, and PTB in FIG. 3B are formed and optically read, and the mark PTB corresponding to the B toner image and other marks are combined. Is calculated, and PTY-PTB, PTC-PTB, and PTM-PTB are calculated, and the "average deviation from the ideal value" is calculated using these.
[0082]
The distance from the writing position to the transfer unit is “d”, the amount of resist to be adjusted is δ, and the “linear velocity before correction” of the photosensitive drum is V ₀ Then, the time from the writing position to the transfer portion: T ₀ = D / V ₀ And this time: T ₀ In the meantime, the average linear velocity running on the distance: d + δ: V _A = (D + δ) V ₀ / d, the control amount is V _A -V ₀ = ΔV ₀ / d. By calculating the control amount for each photosensitive drum and controlling the linear velocity, it is possible to achieve good registration.
[0083]
As described above, the information of the mark image read by the image mark reading sensor SN is sent to each color error detection unit 12, and the reading time difference: “the deviation from the ideal value” of PTY-PTB, PTC-PTB, PTM-PTB is calculated. , And these deviation amounts: δ are calculated by the above-mentioned equation: V = (d + δ) V ₀ / d formula, average speed: V _A Is calculated for each latent image carrier, and is input to the motor Y driver to the motor B driver, so that the motor B, the motor Y, the motor M, and the motor for driving the photosensitive drums 91B, 91Y, 91M, 91C to 91C are driven. C can be operated at a target speed.
[0084]
In the case where the "transfer device 920 using the sheet conveying belt 9200" in FIG. 2 is used instead of the intermediate transfer belt 9041, good registration can be performed similarly.
[0085]
In each of the embodiments described above, if the linear speed of the photosensitive drum is changed, a “relative speed” occurs between the intermediate transfer belt or the sheet conveying belt and the photosensitive drum, but “ The change in the magnification of the image due to the change in the linear velocity of the photosensitive drum "does not occur.
[0086]
That is, such a change in magnification does not occur unless the linear velocity of the intermediate transfer belt or the sheet conveying belt is accompanied by the photosensitive drum. This is because when the linear velocity of the photosensitive drum is increased, a phenomenon that “the image is stretched in the exposed portion and contracted in the transfer portion” occurs, and the magnification of the image on the intermediate transfer belt does not change.
[0087]
However, when the relative speed between the linear speed of the photosensitive drum and the linear speed of the intermediate transfer belt or the sheet conveyance belt increases, when the toner image is transferred from the photoconductor drum to the intermediate transfer belt or the sheet conveyance belt, the toner image is disturbed. Therefore, it is preferable that the relative speed between the two be as small as possible.
[0088]
In the description so far, "optical scanning device for writing an image in each image forming station" is not particularly described. In carrying out each of the above-described embodiments, a known appropriate device known in connection with a tandem-type image forming apparatus can be used as the optical scanning device. For example, an independent optical scanning device (generally constituted by a light source, an optical deflecting unit, and an imaging optical system such as an fθ lens) may be provided for each image forming station.
[0089]
Alternatively, a light beam that scans a plurality of latent image carriers with light may be deflected by a common rotary polygon mirror.
[0090]
FIG. 5A is an explanatory diagram showing a main part of the “optical scanning device using a common rotary polygon mirror”. Light beams from light sources LSB, LSY, LSM, and LSC that emit light beams for writing black (B) images, yellow (Y) images, magenta (M) images, and cyan (C) images rotate in common with these light beams. As shown in the figure, the light is reflected by the polygon mirror 100 and becomes a deflected light beam that is deflected with the rotation of the rotary polygon mirror 100. The light beam is guided to a corresponding latent image carrier via an fθ lens or the like (not shown) to perform writing.
[0091]
Writing of one line (single beam method) or several lines (multi-beam scanning not commanded) is performed on one deflecting reflection surface of the rotary polygon mirror 100. The deflecting light beams directed to the respective latent image carriers are detected by separate synchronization sensors Y to B (FIG. 5B), and the writing start is synchronized based on the detection signals of these synchronization sensors.
[0092]
In this method, even if "writing is to be started in the middle of rotation of the deflecting reflection surface" for registration, it is necessary to wait for the next deflecting reflection surface. "Rotation for rotation time" occurs as a registration deviation. In addition, since the rotating polygon mirror 100 rotates continuously and optical scanning of each electrostatic latent image is performed at the same time, “registration deviation for each color toner image” cannot be corrected by adjusting the rotation phase of the rotating polygon mirror 100. .
[0093]
In the embodiment shown in FIG. 5, the optical scanning of each latent image carrier is performed by a multi-beam scanning method using two light beams, and the writing density is assumed to be 600 dpi. In this case, the size of one dot is 25.4 mm (1 inch) /600=0.0423 mm, and two lines are optically scanned by one deflecting reflection surface, so that 0.0423 × 2 = 0.0846 mm is one time. This is the “distance in the sub-scanning direction” written by optical scanning. In other words, the “rotation time shift of one deflecting reflection surface” in the rotary polygon mirror 100 is 0.0846 mm.
[0094]
The “registration level at which the resist deviation can be visually confirmed” is generally set to 0.03 mm, and the resist deviation of the rotation time deviation: 0.0846 mm is a size that is clearly visually recognized.
[0095]
In the embodiment shown in FIG. 5, the registration deviation is corrected by effectively considering such a deviation of the rotation time of the rotary polygon mirror. The transfer of the toner image is assumed to be "in the case of using the intermediate transfer belt", but the following description can be applied to "in the case of using the sheet transport belt" as it is.
[0096]
As in the above-described embodiments, the information of the marker image read by the image reading sensor SN is sent to each color error detection unit 12, and the reading time difference: PTY-PTB, PTC-PTB, PTM-PTB and the target time difference Is calculated. For “Δt” obtained by converting “displacement: δ” of each color toner image into time, a natural number: N that minimizes “| Δt−N × rotation time for one deflecting reflection surface |” for each color, Each color error calculation unit 12 calculates the error.
[0097]
Referring to FIG. 5C, time: t1 is “time when the deflection / reflection surface is switched by rotation of the rotary polygon mirror 100”. In this case, the minimum of | Δt−N × rotation time for one deflecting reflection surface | holds true for a natural number: N = 4.
[0098]
In this case, the writing timing is shifted from T1 to T1 'in the figure, and at the same time, the remaining error: Δt1 is corrected by controlling the linear velocity of the latent image carrier. That is, each color error calculation unit 12 calculates a control amount (a linear velocity correction amount) corresponding to the above-mentioned error amount: Δt1 for each latent image carrier, and outputs the motor Y to motor B via the motor Y driver to the motor B driver. Control.
[0099]
That is, when the “time difference” between the reading time difference: PTY-PTB, PTC-PTB, and PTM-PTB and the target time difference is performed, each color error calculation unit 12 causes the light sources Y to B to emit light, and the synchronization sensor Y to synchronization. The signal from the sensor B is taken in, and | Δt−N × the time required for one deflection / reflection surface | is calculated as a natural number: N which minimizes the value. The time required for switching: the light emission timings of the light sources Y and B are corrected so as to be shifted by t1, and the remaining time: ΔT1 is corrected by the “linear velocity control of the latent image carrier” described above.
[0100]
By performing such control for each latent image carrier, it is possible to satisfactorily correct registration deviation and transfer a plurality of toner images.
[0101]
In this transfer method, a portion having a large resist deviation is performed by “writing timing correction” and the remaining portion is performed by controlling the linear speed of the latent image carrier, so that the change in linear speed due to the correction: ΔV is small. Therefore, the relative speed between the intermediate transfer belt or the sheet conveying belt and the latent image carrier does not increase, and image defects due to extreme relative speed variations can be prevented. In other words, the margin for “variation in the relative speed between the latent image carrier and the intermediate transfer belt or the sheet conveyance belt” is increased.
[0102]
"If the relative speed between the latent image carrier and the intermediate transfer belt is extremely high, the driving of the intermediate transfer belt and the latent image carrier will be overloaded, and the torque will increase, and the slack and elongation of the belt will occur." These phenomena can be effectively prevented.
[0103]
A scale for detecting the linear velocity is formed on the intermediate transfer belt or the sheet conveying belt, and the scale is detected by the scale detecting means. Based on the detected linear velocity, the driving of the sheet conveying belt is driven by the belt drive. The control by the control means is conventionally known (Patent Document 4 and the like), and in each of the embodiments described above, such linear velocity control is performed on the intermediate transfer belt and the sheet conveyance belt. The “belt drive control unit” in this case can be a control unit (a microcomputer or the like) that controls the entire image forming apparatus.
[0104]
When using a sheet transport belt, the “variation factor” such as the surface condition and hardness of the transfer paper is larger than that of the intermediate transfer belt, and the movement is often unpredictable. Since the variation factors need to be more severely removed, the transfer method of the present invention is effective.
[0105]
In the embodiment shown in FIG. 4 and FIG. 5, the linear velocities of the four latent image carriers (photosensitive drums) 91B to 91C are controlled independently of each other. The misregistration between the black toner image and the toner image of the other color is not so noticeable, and the misregistration between the toner images of each color (Y, M, C) other than black is not so noticeable.
[0106]
Therefore, in such a case, instead of individually controlling the linear velocities of the four latent image carriers, the linear velocity of at least one of the plurality of latent image carriers (forming a black toner image) is set to The control means may control the latent image carrier independently of the linear velocity of the other latent image carrier.
In the embodiment described above with reference to FIGS. 4 and 5, each of the electrostatic latent images formed by optical writing is written on a plurality of rotationally driven latent image carriers 91B to 91C by different latent images. Each image carrier is visualized with a toner of a different color to obtain a plurality of toner images of different colors, and the plurality of toner images are superimposed on the same sheet-shaped recording medium S from each latent image carrier. In the image forming method of forming a multi-color image or a color image by transferring a plurality of toner images onto a sheet-shaped recording medium S, a mark image for transfer registration is formed on each latent image carrier. The mark images PTB to PTC are transferred onto a common transfer medium 9041, and the positional relationship between the mark images is optically read and detected by the detecting means SN. The multiple toner image transfer method (claim 1) in which the linear velocity of the plurality of latent image carriers is controlled by the control means 12 based on the above and the transfer is performed by reducing the registration deviation between the transferred toner images. Is done.
[0107]
Further, an intermediate transfer belt 9041 is used, and using this intermediate transfer belt 9041 as a common transfer medium, a mark image for transfer position alignment on each latent image carrier is transferred and optically read and detected by the detecting means SN. The toner images of different colors formed on a plurality of photoconductors are primarily transferred to an intermediate transfer belt 9041, and a multicolor image or a color image is obtained on the intermediate transfer belt. The image is secondarily transferred onto the sheet-like recording medium S from above (claim 2).
[0108]
In these embodiments, instead of the intermediate transfer belt, a sheet conveyance belt 9200 that conveys the sheet-shaped recording medium S is used, and the sheet conveyance belt is used as a common transfer medium for transfer position alignment on each latent image carrier. Sheet images of the toner images of different colors formed on a plurality of latent image carriers are transferred by suction by a sheet conveying belt. A plurality of color images or a color image can also be transferred by superimposing them on each other (claim 3).
[0109]
In the embodiment of FIGS. 4 and 5, the linear velocities of the plurality of latent image carriers 91B to 91C are controlled independently of each other by the control unit 12 based on the detection result by the detection unit SN. Further, in the embodiment shown in FIG. 5, the reduction of the registration deviation between the transferred toner images is performed in combination with the "control of the optical writing start timing" (claim 7).
[0110]
In the embodiment described with reference to FIGS. 3 to 5, each of the electrostatic latent images formed by optical writing on a plurality of rotationally driven latent image carriers 91 </ b> B to 91 </ b> C is used as a multiple toner image transfer device. Are visualized with toners of different colors for different latent image carriers to obtain a plurality of toner images having mutually different colors, and these toner images are transferred from each latent image carrier to the same sheet-shaped recording medium S. In the image forming method of forming a multi-color image or a color image by superimposing and transferring a plurality of toner images, a device for transferring a plurality of toner images to a sheet-shaped recording medium, which is formed on each latent image carrier by optical writing The detection means SN for optically reading and detecting each mark image PTB-PTC for transfer position alignment, which is visualized as a toner image and transferred onto a common transfer medium, is detected by the detection means. Control amount generating means for generating a control amount for controlling the linear velocities of the plurality of latent image carriers based on a positional relationship between the plurality of latent images, and a plurality of latent images based on the control amount generated by the control amount generating means. Control means for controlling the rotational driving of the image carrier, wherein the control amount generating means generates a control amount for reducing a registration shift between the transferred toner images (claim 8).
[0111]
The image forming apparatus further includes an intermediate transfer belt 9041, which uses the intermediate transfer belt as a common transfer medium to transfer mark images PTB to PTC for transfer position alignment on each latent image carrier, and optically reads the mark images PTB to PTC by the detection unit SN. Primary transfer means (9041 or the like) for detecting and simultaneously transferring toner images of different colors formed on a plurality of photoconductors to an intermediate transfer belt to obtain a multicolor image or a color image; There is provided secondary transfer means (905 or the like) for secondary transfer of the color image from the intermediate transfer belt onto the sheet-like recording medium.
[0112]
Then, instead of the intermediate transfer belt in the above-described embodiment, a sheet conveyance belt 9200 that conveys the sheet-shaped recording medium S is used, and the sheet conveyance belt is used as a common transfer medium to adjust the transfer position on each latent image carrier. Sheet image recording medium in which toner images of different colors formed on a plurality of photoconductors are adsorbed and conveyed by a sheet conveyer belt while transferring mark images PTB to PTC for optical detection and detection by a detecting unit. The image forming apparatus may have a transfer unit (920 or the like) for transferring the image on the 9200 in a superimposed manner (claim 11).
[0113]
Further, a scale for detecting the linear velocity is formed on the intermediate transfer belt 9041 or the sheet conveying belt 9200, and a scale detecting means for detecting the scale and an intermediate speed based on the linear velocity detected by the scale detecting means are provided. The rotational drive of the transfer belt or the sheet transport belt can be drive-controlled by the intermediate transfer belt drive control means.
[0114]
In the multi-toner image transfer apparatus shown in FIG. 3 according to the embodiment, the control amount generation unit determines the linear velocities of the plurality of latent image carriers 91B to 91C based on the positional relationship between the mark images detected by the detection unit SN. The control unit uniformly controls the linear velocities of the plurality of latent image carriers based on the control amount generated by the control amount generation unit (claim 13).
[0115]
In the multi-toner image transfer apparatus according to the embodiment shown in FIGS. 4 and 5, the control unit 12 controls the control amount generated by the control amount generation unit 12 based on the positional relationship between the mark images detected by the detection unit SN. The linear velocities of the plurality of latent image carriers 91B to 91C are controlled independently of each other based on the amount (claim 15).
[0116]
The multi-toner image transfer apparatus described in the embodiment shown in FIGS. 3 to 5 is applied to the image forming apparatus shown in FIGS. Forming a latent image, visualizing each formed electrostatic latent image with a toner of a different color for each different latent image carrier, obtaining a plurality of toner images of different colors from each other, In an image forming apparatus that overlaps and transfers from each latent image carrier onto the same sheet-shaped recording medium S to form a multi-color image or a color image, each latent image carrier transfers a color As a transfer unit for transferring a plurality of toner images different from each other, the multi-toner image transfer device according to any one of claims 8 to 15 is used (claim 16).
[0117]
In these image forming apparatuses, the number of latent image carriers is four, and the four latent image carriers 91B to 91C are provided with a black (B) toner image and Y, M, and C toner images of the other three colors. Wherein the linear image of the latent image carrier 91B on which the black toner image is formed has a linear velocity of another latent image carrier. The linear writing speed is controlled independently of the linear velocity of the image bearing member (Claim 17), and the optical writing means for writing the electrostatic latent image on each latent image carrier is of an optical scanning type which deflects a light beam by a rotating mirror (Claim 18). In the image forming apparatus using a plurality of toner images shown in the embodiment shown in FIG. 5, the rotating mirror 100 for deflecting a light beam is commonly used for deflecting a light beam for optically scanning a plurality of latent image carriers. ), Optical writing by optical writing means for writing an electrostatic latent image on each latent image carrier The timing of write start is controllable for each image bearing member (claim 20).
[0118]
【The invention's effect】
As described above, according to the present invention, a novel multi-toner image transfer method, apparatus, and image forming apparatus can be realized.
ADVANTAGE OF THE INVENTION As mentioned above, the multiple toner image transfer method and apparatus of this invention can reduce or prevent registration deviation in the transfer process between several toner images effectively. Therefore, the image forming apparatus using the multi-toner image transfer device can effectively reduce and prevent the misregistration of the registration and obtain a good multi-color image or a good color image.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of an image forming apparatus.
FIG. 2 is a diagram for explaining another embodiment of the image forming apparatus.
FIG. 3 is a diagram for describing one embodiment of a multi-toner image transfer device.
FIG. 4 is a diagram for explaining another embodiment of the multi-toner image transfer device.
FIG. 5 is a diagram for explaining another embodiment of the multi-toner image transfer device.
[Explanation of symbols]
91B, 91Y, 91M, 91C Latent image carrier (photosensitive drum)
9041 Intermediate transfer belt
PTB, PTY, PTM, PTC mark image

Claims (20)

Each electrostatic latent image formed by optical writing is visualized with a different color toner for each different latent image carrier on a plurality of rotationally driven latent image carriers, and a plurality of toner images of different colors are formed. The plurality of toner images are obtained by superimposing and transferring the plurality of toner images onto the same sheet-shaped recording medium from each latent image carrier to form a multicolor image or a color image. Is transferred to the sheet-shaped recording medium,
A mark image for transfer position alignment is formed as a toner image on each latent image carrier, these mark images are transferred onto a common transfer medium, and the positional relationship between the mark images is optically read by a detecting means. Detect
A control device controls the linear velocities of the plurality of latent image carriers on the basis of the detection result by the detection unit, and reduces the registration deviation between the transferred toner images to perform the transfer. Transfer method. The method according to claim 1, wherein
Using an intermediate transfer belt, using this intermediate transfer belt as a common transfer medium, transfer a mark image for transfer position alignment on each latent image carrier, and optically read and detect by a detection unit,
The toner images of different colors formed on a plurality of photoconductors are primarily transferred to the intermediate transfer belt to obtain a multicolor image or a color image on the intermediate transfer belt, and the multicolor image or the color image is A multi-toner image transfer method, wherein a secondary transfer is performed onto the sheet-like recording medium from the intermediate transfer belt. The method according to claim 1, wherein
Using a sheet transport belt that transports a sheet-shaped recording medium, using this sheet transport belt as a common transfer medium, transfer a mark image for transfer position alignment on each latent image carrier, and optically read and detect by a detection unit. And
The toner images of different colors formed on the plurality of latent image carriers are transferred one on top of the other on the sheet-shaped recording medium sucked and conveyed by the sheet conveying belt to form a multi-color image or a color image. A method for transferring a plurality of toner images, the method comprising: The method for transferring a plurality of toner images according to any one of claims 1 to 3,
A method for transferring a plurality of toner images, wherein a linear velocity of a plurality of latent image carriers is uniformly controlled by a control unit based on a detection result by the detection unit. The method for transferring a plurality of toner images according to any one of claims 1 to 3,
A method for transferring a plurality of toner images, wherein a linear speed of at least one of a plurality of latent image carriers is controlled independently of a linear speed of another latent image carrier by a control unit based on a detection result by a detecting unit. . The method for transferring a plurality of toner images according to claim 5,
A method of transferring a plurality of toner images, wherein the linear velocities of a plurality of latent image carriers are controlled independently of each other by a control unit based on a detection result by the detection unit. The method for transferring a plurality of toner images according to any one of claims 1 to 6,
A method for transferring a plurality of toner images, characterized in that the registration deviation between the transferred toner images is reduced by controlling the start timing of optical writing. Each electrostatic latent image formed by optical writing is visualized with a different color toner for each different latent image carrier on a plurality of rotationally driven latent image carriers, and a plurality of toner images of different colors are formed. The plurality of toner images are obtained by superimposing and transferring the plurality of toner images onto the same sheet-shaped recording medium from each latent image carrier to form a multicolor image or a color image. Is transferred to the sheet-shaped recording medium,
Detecting means for optically reading and detecting each mark image for transfer position alignment, formed by optical writing on each latent image carrier, visualized as a toner image, and transferred on a common transfer medium;
Control amount generating means for generating a control amount for controlling the linear velocities of the plurality of latent image carriers based on a positional relationship between the mark images detected by the detecting means;
Control means for controlling the rotation drive of the plurality of latent image carriers based on the control amount generated by the control amount generation means,
The multi-toner image transfer apparatus according to claim 1, wherein the control amount generating means generates a control amount for reducing registration deviation between the transferred toner images. The multi-toner image transfer device according to claim 8,
The image forming apparatus has an intermediate transfer belt, using the intermediate transfer belt as a common transfer medium, transferring a mark image for transfer position alignment on each latent image carrier, optically reading and detecting by a detecting unit, and a plurality of photosensitive drums. Primary transfer means for primary-transferring toner images of different colors formed on the body to the intermediate transfer belt to obtain a multi-color image or a color image;
A multi-toner image transfer apparatus, comprising: a secondary transfer means for secondary-transferring the multi-color image or the color image from the intermediate transfer belt onto a sheet-like recording medium. The multi-toner image transfer device according to claim 8,
It has a sheet transport belt that transports the sheet-shaped recording medium, and uses this sheet transport belt as a common transfer medium to transfer mark images for transfer position alignment on each latent image carrier and optically read by a detection unit. As well as detecting
A plurality of toner images having transfer means for transferring toner images of different colors formed on a plurality of photoconductors onto the sheet-shaped recording medium sucked and conveyed by the sheet conveyance belt, in a superimposed manner; Transfer device. The multi-toner image transfer device according to claim 9,
A scale for detecting the linear velocity of the intermediate transfer belt is formed on the intermediate transfer belt, and a scale detecting means for detecting the scale and a rotational drive of the intermediate transfer belt are controlled based on the linear velocity detected by the scale detecting means. A multi-toner image transfer device comprising an intermediate transfer belt drive control means. The multi-toner image transfer device according to claim 10,
A scale for detecting the linear velocity is formed on the sheet conveying belt, and a scale detecting means for detecting the scale and a rotational drive of the sheet conveying belt are controlled based on the linear velocity detected by the scale detecting means. A multi-toner image transfer device comprising a sheet conveyance belt drive control means. The multi-toner image transfer device according to any one of claims 8 to 12,
Based on the positional relationship between the mark images detected by the detecting means, the control amount generating means generates a control amount for uniformly controlling the linear velocities of the plurality of latent image carriers,
A multi-toner image transfer apparatus, wherein the control means uniformly controls the linear velocities of the plurality of latent image carriers based on the control amount generated by the control amount generating means. The multi-toner image transfer device according to any one of claims 8 to 12,
The control amount generating means controls at least one linear velocity of the plurality of latent image carriers independently of the linear velocities of the other latent image carriers based on the positional relationship between the mark images detected by the detecting means. To generate a controlled variable
A multi-toner image transfer apparatus, wherein the control means controls at least one linear velocity of the plurality of latent image carriers independently of the linear velocity of the other latent image carriers. The multiple toner image transfer device according to claim 14,
Control amount generating means generates a control amount for controlling the linear velocity of each latent image carrier,
A multi-toner image transfer apparatus, wherein the control means controls the linear velocities of the plurality of latent image carriers independently of each other based on the control amount generated by the control amount generating means. An electrostatic latent image is formed by optical writing on a plurality of rotationally driven latent image carriers, and the formed electrostatic latent images are visualized with toners of different colors for different latent image carriers, and color images are formed on each other. Image forming apparatus that obtains a plurality of toner images different from each other, and superimposes and transfers the plurality of toner images from each latent image carrier onto the same sheet-shaped recording medium to form a multi-color image or a color image At
16. A transfer device for transferring a plurality of toner images having different colors from each latent image carrier to a sheet-shaped recording medium, comprising the multi-toner image transfer device according to any one of claims 8 to 15. Image forming apparatus. The image forming apparatus according to claim 16,
The number of latent image carriers is four, and a black toner image and toner images of the other three colors are formed on these four latent image carriers, respectively.
16. The multi-toner image transfer device according to claim 14, wherein a linear velocity of a latent image carrier on which a black toner image is formed is controlled independently of a linear velocity of another latent image carrier. An image forming apparatus comprising: The image forming apparatus according to claim 16, wherein
An image forming apparatus, wherein an optical writing means for writing an electrostatic latent image on each latent image carrier is of an optical scanning type in which a rotating mirror deflects a light beam. The image forming apparatus according to claim 18,
An image forming apparatus, wherein a rotating mirror for deflecting a light beam is shared for deflecting a light beam for optically scanning a plurality of latent image carriers. The image forming apparatus according to any one of claims 16 to 19,
An image forming apparatus wherein the timing of starting optical writing by an optical writing unit for writing an electrostatic latent image on each latent image carrier can be controlled for each latent image carrier.

Images