JP2008009107A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of correcting the positional deviation of a toner image with appropriate positional deviation amount. <P>SOLUTION: By predicting the positional deviation amount of the toner image when forming the toner image from positional deviation amount predicting information, the positional deviation amount of the toner image when forming the toner image is obtained. Therefore, the drive of an image carrier when forming the toner image is controlled to correct the positional deviation of the toner image in accordance with the obtained positional deviation amount of the toner image when forming the toner image. Namely, the positional deviation of the toner image when forming the toner image is corrected to remove the positional deviation amount of the toner image when forming the toner image, which is a predicted value. Therefore, the positional deviation amount is accurately predicted, whereby an image forming position on the image carrier is appropriately adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus that obtains an image by transferring a visible image formed on the surface of an image carrier to a transfer body.

  As an image forming apparatus, there is known an image forming apparatus that forms an image by forming a toner image on a photosensitive member as a latent image carrier, and transferring the toner image on a transfer member such as a recording paper or an intermediate transfer member. ing. In such an image forming apparatus, when the transfer position of the toner image with respect to the transfer body is relatively shifted, there occurs a problem that the toner image is displaced. As a cause of this positional deviation, a member in the apparatus main body is thermally expanded due to a temperature rise in the apparatus main body, and the member is distorted. For example, when a member of an optical writing unit that irradiates a photosensitive member with a light beam via a reflection mirror and writes a latent image on the photosensitive member is thermally expanded, distortion occurs in the optical writing unit, and the optical path of the optical beam is changed. Due to the deviation, the writing position of the latent image on the photosensitive member is displaced. As a result, the toner image formed on the photoconductor is displaced. Therefore, in order to suppress the positional deviation of the toner image, for example, in the image forming apparatus described in Patent Document 1, the positional deviation is detected on the transfer body based on the result of detecting the temperature in the apparatus main body by the temperature detecting means. A patch pattern of a toner image is formed, and a positional deviation of the patch pattern is detected by a pattern detection unit. The positional deviation of the image is corrected according to the detection result of the positional deviation of the patch pattern.

JP-A-8-286458

  However, in the image forming apparatus described in Patent Document 1, it is necessary to form a patch pattern for detecting misalignment and detect the misalignment of the patch pattern in order to grasp whether the misalignment of the toner image has occurred. is there. For this reason, in the configuration in which the positional deviation of the toner image is corrected after detecting the positional deviation of the patch pattern as in the image forming apparatus described in Patent Document 1, the toner that is corrected for positional deviation after the patch pattern is formed. It may take time to form an image. In this case, when the temperature in the apparatus main body changes with time, and the temperature in the apparatus main body is different between the time when the patch pattern is formed and the time when the toner image is formed based on the patch pattern, the patch pattern is formed. As a result, the amount of misalignment of the toner image is different between the time when the toner image is formed and the time when the toner image is formed. For this reason, there is a problem that even if the positional deviation at the time of forming the toner image is corrected based on the positional deviation amount at the time of forming the patch pattern, the positional deviation of the toner image cannot be corrected with an appropriate positional deviation amount.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of correcting a positional deviation of a toner image with an appropriate positional deviation amount.

In order to achieve the above object, the invention of claim 1 includes an image carrier, a driving unit for driving the image carrier, a toner image forming unit for forming a toner image on the image carrier, and the image. Transfer means for finally transferring the toner image formed on the carrier onto the recording body, and fixing means for fixing the toner image on the recording body on the recording body by applying at least heat. A positional deviation amount prediction information acquisition unit configured to acquire positional deviation amount prediction information, which is information for predicting the positional deviation amount of the toner image, and the positional deviation amount based on the positional deviation amount prediction information. A misregistration amount prediction unit that predicts the amount, and a drive control unit that controls driving of the driving unit so as to correct the misregistration amount according to a prediction result of the misregistration amount prediction unit. It is a feature.
According to a second aspect of the present invention, there are provided a plurality of image carriers, a plurality of driving units for respectively driving the plurality of image carriers, and a toner image forming unit for forming a toner image on the plurality of image carriers. A transfer means for superimposing the toner images formed on the plurality of image carriers and finally transferring the toner images onto the recording medium; and at least applying heat to the toner images on the recording medium. In an image forming apparatus including a fixing unit for fixing on top, a positional shift amount prediction information acquisition unit that acquires positional shift amount prediction information that is information for predicting a positional shift amount of the toner image, and the positional shift amount prediction Based on the information, a positional deviation amount prediction unit that predicts the positional deviation amount, and each of the plurality of driving units so as to correct the positional deviation amount according to a prediction result of the positional deviation amount prediction unit. Having drive control means for controlling drive It is an feature.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the positional deviation amount prediction information includes an elapsed time from the heating state change time of the fixing unit. It is.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect, the image forming apparatus further comprises a recording body reversing unit that reverses the front and back of the recording body. It includes the elapsed time from the start of operation of the recording medium reversing means or the elapsed time from the end of image formation on both sides of the recording medium.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the positional deviation amount prediction information includes an elapsed time from the time when the driving unit changes the driving state. It is a feature.
According to a sixth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, or fifth aspect, the image forming apparatus further includes a latent image writing unit that writes a latent image on the image carrier. The prediction information includes an elapsed time from when the latent image writing means is turned on or an elapsed time from when the latent image writing means is turned off.
The invention according to claim 7 is the image forming apparatus according to claim 1, further comprising temperature detecting means for detecting a use environment temperature. Includes the detection result of the temperature detection means.
According to an eighth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth or seventh aspect, at least conversion that is information for converting the positional deviation amount prediction information into the positional deviation amount Information storage means for storing information, positional deviation detection means for detecting positional deviation of the toner image, and conversion information correction means for correcting the conversion information based on the detection result of the positional deviation detection means. It is characterized by.

  In the present invention, by predicting the positional deviation amount of the toner image at the time of toner image formation from the positional deviation amount prediction information, the positional deviation amount of the toner image at the time of toner image formation can be grasped. Accordingly, the driving of the image carrier during the toner image formation is controlled so that the positional deviation correction of the toner image is performed according to the amount of positional deviation of the toner image during the toner image formation grasped in this way. Can do. That is, instead of correcting the positional deviation of the toner image at the time of forming the toner image so that the amount of positional deviation of the patch pattern formed before the time of forming the toner image is eliminated as in the prior art, However, the positional deviation correction of the toner image at the time of the toner image formation is performed so that the amount of positional deviation of the toner image at the time of the toner image formation is eliminated. Therefore, the image forming position on the image carrier is appropriately adjusted by accurately predicting the positional deviation amount.

  As described above, according to the present invention, the image forming position on the image carrier is adjusted in accordance with the amount of positional deviation of the toner image at the time of toner image formation for correcting the positional deviation of the toner image. There is an excellent effect that the positional deviation of the toner image can be corrected by the amount.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic color laser printer (hereinafter simply referred to as “printer”) 1 will be described.
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a printer 1 according to the present embodiment. The printer 1 has a configuration in which a paper feeding unit 2 is provided at a lower portion of the apparatus main body, and an image forming unit 3 is disposed above the paper feeding unit 2. A paper discharge tray 60 is formed on the upper surface of the apparatus. A broken line in the figure indicates a conveyance path of a recording sheet as a recording medium. The recording paper is fed from the paper feeding unit 2, the image formed by the image forming unit 3 is transferred to the surface, is fixed by the fixing device 50, and is ejected to the paper ejection tray 60. In addition, as indicated by a symbol h in the figure, manual sheet feeding is possible from the side of the apparatus. A double-sided device 90 is mounted on the side surface of the apparatus main body. When forming an image on both sides of a recording sheet, the image is formed on one side, fixed by the fixing device 10, and then transported as indicated by a broken line r in the figure. Then, the paper is fed again through the re-conveying unit 40, and an image is formed on the other surface.

  In the image forming unit 3, a plurality of drum-like photosensitive drums 5Y, 5M, 5C, and 5Bk are juxtaposed as a plurality of latent image carriers, and yellow (Y), magenta (M), cyan (C), An image corresponding to each color of black (Bk) is formed. The photosensitive drums 5Y, 5M, 5C, and 5Bk are each driven to rotate by a drum motor (not shown). The order of colors is not limited to this, and can be set arbitrarily. Around each of the four photosensitive drums 5Y, 5M, 5C, and 5Bk, in order to form an image by an electrophotographic process, charging units 6, 7, 8, and a charging roller, a charging brush, a charging charger, and the like are provided. 9, exposure units for light beams L 1, L 2, L 3, and L 4 from the optical scanning device 8, developing devices 9 Y, 9 M, 9 C, and 9 Bk for each color, cleaning units 18 Y, 18 M, 18 C, and 18 Bk, and the like. Thus, each color image can be formed on each of the photosensitive drums 5Y, 5M, 5C, and 5Bk. The optical scanning device 8 is disposed obliquely above the image forming unit 3 in which four photosensitive drums 5Y, 5M, 5C, and 5Bk are arranged in parallel.

  The transfer conveyance belt device 20 is provided with an endless belt-shaped transfer conveyance belt 21. The transfer / conveying belt 21 is stretched around a driving roller 22, a driven roller 23, and a tension roller 24. On the inner side of the upper running surface of the transfer conveyance belt 21, a transfer brush 28 constituting transfer means is provided at positions facing the photosensitive drums 5Y, 5M, 5C, 5Bk of the color image forming units 4Y, 4M, 4C, 4Bk, respectively. Are in contact. A transfer bias having a polarity opposite to the charging polarity of the toner is applied to the transfer brush 28. Further, a paper suction roller 27 is provided above the driven roller 23 with the transfer conveyance belt 21 interposed therebetween. The recording sheet is sent out from between the driven roller 23 and the suction roller 27 onto the transfer conveyance belt 21 and conveyed while being electrostatically adsorbed on the transfer conveyance belt 21 by the bias voltage applied to the adsorption roller 27. The

  The fixing device 10 employs a belt fixing method in this embodiment, and has a configuration in which a fixing belt 14 is wound around a fixing roller 12 and a heating roller 13. The fixing roller 12 and the pressure roller 11 are in pressure contact with each other to form a fixing nip. The heating roller 13 has a built-in heater 15.

  Next, the optical scanning device 8 will be described. FIG. 2 is a top view of the optical scanning device 8. FIG. 3 is a cross-sectional view taken along the line A-A ′ in the optical scanning device of FIG. 2. As shown in the configuration example of FIG. 3, the optical scanning device 8 includes four light source units 52, 53, 54, and 55 and light beams L1, L2, L3, and L4 from the light source units in two symmetrical directions. An optical deflector 62 that distributes and scans the light, and a plurality of light beams L 1, L 2, L 3, and L 4 that are arranged symmetrically in the two directions around the optical deflector 62 and are deflected and scanned by the optical deflector 62. Imaging lenses 63, 64, 69, 70, 71, 72, which are optical system members that are guided and imaged on the scanned surfaces of the corresponding photosensitive drums 5Y, 5M, 5C, 5Bk, and mirrors for turning back the optical path. 65, 66, 67, 68, 73, 74, 75, 76, 77, 78, 79, 80. These components are housed in one housing 50. More specifically, the housing 50 includes a base 50A on which the optical deflector 62 and the optical system are disposed, and a frame-like side wall 50B surrounding the base 50A, and the base 50A is substantially at the center of the side wall 50B. The four light source units 52, 53, 54, and 55 are arranged on the side wall 50B of the housing 50, and the light deflector 62 is substantially at the center of the base 50A of the housing 50. The imaging lenses 63, 64, 69, 70, 71, 72, which are optical system members, and mirrors 65, 66, 67, 68, 73, 74, 75, 76, 77, 78 for turning back the optical path. , 79, 80 are arranged separately on both surfaces (upper surface side and lower surface side) of the base 50A. Covers 87 and 88 are provided at the upper and lower portions of the housing 50, and an opening through which the light beam passes is provided in the lower cover 87, and dustproof glasses 83, 84, 85, and 86 are provided in the openings. Is attached.

  The optical scanning device 8 converts color-separated image data input from a document reading device such as a scanner (not shown) or an image data output device such as a personal computer, a word processor, and a facsimile reception unit into a light source driving signal. Accordingly, the light source (semiconductor laser [LD]) in each light source unit 52, 53, 54, 55 is driven to emit a light beam. The light beams emitted from the light source units 52, 53, 54, and 55 pass through the cylindrical lenses 56, 57, 58, and 59 for surface tilt correction and reach the optical deflector 62 directly or via the mirrors 60 and 61. The two-stage polygon mirrors 62a and 62b rotated at a constant speed by the polygon motor 62c are deflected and scanned in two symmetrical directions. In the configuration shown in FIG. 3, the polygon mirror is divided into two upper and lower stages for the light beams L2 and L3 and for the light beams L1 and L4. The light beams L1, L2, L3, and L4 may be deflected and scanned.

  The light beam deflected and scanned in two directions by two beams by the polygon mirrors 62a and 62b of the optical deflector 62 is, for example, from an fθ lens having a function of correcting the position of the upper and lower two-layer scanning lines in the direction corresponding to the main scanning. Are passed through the first imaging lenses 63 and 64, respectively, are folded by the first folding mirrors 65, 66, 67 and 68 and pass through the opening of the base 51, and then, for example, the position of the scanning line corresponds to the sub-scanning. Passing through second imaging lenses 69, 70, 71, 72 made of long toroidal lenses (WTL) having a function of correcting in the direction, and second folding mirrors 73, 75, 77, 79, Three-fold mirrors 74, 76, 78, and 80 and dust-proof glasses 83, 84, 85, and 86 are irradiated onto the photoconductor scanning surface for each color to write an electrostatic latent image. In the optical scanning device 8 described above, the four light source units 52, 53, 54, and 55 are composed of a semiconductor laser that is a light source and a collimating lens that collimates the emitted light beam of the semiconductor laser, and these are integrated with the holder. As a black light source unit that is frequently used in black-and-white image formation, for example, the light source unit 54 includes two or more light sources (LDs) and a collimating lens to enable high-speed writing. It is good also as a multi-beam structure provided with the group.

  In the case of a multi-beam configuration, if the light source unit is configured to be rotatable about the optical axis with respect to the side wall 50B of the housing 50, the beam pitch in the sub-scanning direction can be adjusted. For example, the pixel density can be switched to 600 dpi, 1200 dpi, and the like. Further, a synchronization detection mirror (not shown) for taking out the light beam at the scanning start position in the main scanning direction is provided in the optical path of each of the light beams L1, L2, L3, and L4, and is reflected by the synchronization detection mirror. The luminous flux is received by the synchronization detectors 81 and 82, and a scanning start synchronization signal is output. The scanning direction of the light beam deflected and scanned by the optical deflector 62 is the main scanning corresponding direction, which is the axial direction of each of the photosensitive drums 5Y, 5M, 5C, and 5Bk.

  The direction orthogonal to the main scanning correspondence direction is the sub-scanning correspondence direction. The scanning speed uniformity adjustment mechanism and the scanning line inclination adjustment mechanism are composed of actuators that can be electrically driven and controlled by a stepping motor, an adjuster, etc., and from the image output result by the image forming apparatus as described later, The adjustment operation of the adjustment mechanism is carried out by an appropriate drive control.

  In the image forming apparatus according to the present exemplary embodiment, when the transfer position of each color toner image with respect to the transfer body is relatively shifted, the color image is misaligned. FIG. 4 is a diagram schematically showing an actual image position shift with respect to an ideal position, and will be described with reference to this figure.

A. Sub-scanning registration error
As shown in FIG. 4A, this is a phenomenon that shifts in parallel with the sub-scanning corresponding direction with respect to the ideal scanning line. The optical element itself is caused by the sub-scanning corresponding direction performance, the geometric arrangement accuracy of each optical element, and the respective changes due to thermal expansion.

B. Sub-scanning compatible direction: scan line tilt
As shown in FIG. 4B, this is a phenomenon in which the ideal scanning line is inclined in the sub-scanning corresponding direction. This is due to the sub-scanning corresponding direction performance of the optical element itself and the geometric arrangement accuracy of each optical element.

C. Sub-scanning compatible direction: Scan line bending
As shown in FIG. 4C, this is a phenomenon in which an ideal scanning line is bent in the sub-scanning corresponding direction. This is due to the sub-scanning directional performance of the optical element itself, the geometric shape accuracy of each optical element, and deformation.

D. Main scanning compatible direction: Registration error
As shown in FIG. 4D, this is a phenomenon in which the image writing position is shifted for each scanning. In the drawing, the drawing is offset in the sub-scanning corresponding direction. The surface of the polygon mirror N surface is different, the amount of light is different in the image forming mode, multi-beam scanning (N scanning lines are formed in the sub scanning corresponding direction by using N LDs in one scanning) In the case where the LD wavelength is slightly different.

E. Main scanning direction: Magnification deviation
As shown in FIG. 4E, the scanning line length in the main scanning direction is a phenomenon different from the ideal length. The optical element itself is caused by the sub-scanning corresponding direction performance, the geometric arrangement accuracy of each optical element, and the respective changes due to thermal expansion. Further, it occurs due to a slightly different LD wavelength in multi-beam scanning (a method in which N scanning lines are formed in the direction corresponding to the sub-scanning by using N LDs in one scanning).

F. Main scanning direction: Uniform scanning speed
As shown in FIG. 4F, since the scanning speed in the main scanning corresponding direction is microscopically different, the light beam writing cannot be performed at an ideal main scanning corresponding position. This is due to the main scanning-corresponding direction performance of the optical element itself, the geometrical arrangement accuracy of each optical element, and changes due to thermal expansion.

  These misregistrations include those caused by misregistration of replacement parts, etc., but the most frequently occurring misregistration is caused by expansion and contraction due to temperature changes of parts of the optical scanning device 8 such as a reflection mirror. To do. The heat source that causes this temperature change includes the heater 15 of the fixing device 10, recording paper heated during image fixing on one side when performing double-sided printing, a drum motor that drives the photosensitive drum 5, and the optical scanning device 8. An example is a polygon motor 62c provided. Here, the drum motor generates heat when the photosensitive drum 5 is driven. Further, since the polygon motor 62c rotates at a high speed when deflecting the writing light, the bearing portion of the polygon motor 62c generates heat. Furthermore, when the polygon motor 62c is driven, the electronic control components on the circuit board also generate heat. Since the optical scanning device 8 is hermetically sealed with a cover member, the heat generated by the heat generating portions (bearing portion and electronic control component) of the polygon motor 62c is trapped inside the optical scanning device 8, and the inside becomes high temperature. turn into.

  Here, the relationship between the elapsed time from the operation of the heat source and the temperature of the heat source is generally such that the temperature of the heat source increases with time after the heat source is operated. The relationship between the elapsed time from when the heat source is stopped and the temperature of the heat source is generally such that the temperature of the heat source decreases with time after the heat source is stopped. Therefore, in the present embodiment, by grasping the elapsed time, the positional deviation amount corresponding to the elapsed time is information based on a conversion table stored in advance in at least one of the RAM 129 and the ROM 130 in the apparatus main body. Prediction is performed by calculation by the processing unit 120.

For example, when the heater 15 of the fixing device 10 is considered as a heat source, when the information processing unit 120 acquires the elapsed time from the change of the heating state of the heater 15 as the positional deviation prediction information, the heater 15 determines the elapsed time and the position. Since there is a relationship as shown in FIG. 5 and FIG. 6 with the displacement amount, the displacement amount corresponding to the elapsed time is calculated based on the conversion table that satisfies this, and the displacement amount is predicted. . Here, when the heating state is changed, the heater 15 is moved from the operation stop state to the operation state, from the operation state to the operation stop state, or to the low output standby state. 15 when the heating state changes.
Then, in accordance with the prediction result of the positional deviation amount, the rotational speed of the drum motor of each photoconductive drum 5 is minutely changed by a control unit (not shown) to adjust the image forming position, whereby the positional deviation in the sub-scanning direction. Correction can be performed. Further, even when the heat source is not the heater 15 but recording paper heated at the time of fixing when performing double-sided printing, a drum motor, a polygon motor 62c, and the like, conversion of the elapsed time corresponding to each heat source and the amount of positional deviation is performed. By storing the table in the apparatus main body, it is possible to perform positional deviation correction by the same process. In addition, based on the elapsed time from a plurality of heat sources, the information processing unit 120 can also perform positional deviation correction by predicting the positional deviation amount. The heat source is not limited to the heater 15, the recording paper heated by the fixing at the time of double-sided printing, the drum motor, and the polygon motor 62c.

  Moreover, since the gradient of the temperature change with respect to the elapsed time of the heat source changes depending on the use environment temperature of the apparatus main body, if the use environment temperature varies greatly, the positional deviation amount may differ even in the same elapsed time. Therefore, in the present embodiment, the printer 1 is provided with the temperature sensor 150 shown in FIG. 1 for measuring the use environment temperature in order to grasp the use environment temperature. Note that the position where the temperature sensor 150 is provided is not limited to the location shown in FIG. Thereby, when the information processing unit 120 performs the positional deviation prediction, an appropriate positional deviation correction can be performed by using the conversion table according to the use environment temperature. It is also possible to perform misalignment correction based on the detection result of the use environment temperature detected by the temperature sensor.

  Further, the conversion table may change depending on the usage state of the apparatus main body. For this reason, in this embodiment, in order to correct the information in the conversion table to an optimum one, a toner image is formed on the transfer conveyance belt 21, and a misregistration detection unit that detects misregistration of the toner image is provided. .

Next, an example of a mechanism for detecting the positional deviation of the toner image in the image forming apparatus will be described. In this embodiment, an image forming apparatus provided with a transfer conveyance belt will be described. However, the following mechanism can also be used for an image forming apparatus provided with an intermediate transfer member.
FIG. 7 is a diagram illustrating a configuration of a mechanism for detecting a positional deviation of the toner image. A toner mark 115 for detecting misregistration is produced by the image forming apparatus main body image forming unit and transferred onto the transfer conveyance belt 21. A sensor 116 is provided downstream of the transfer conveyance belt 21 in the conveyance direction, and detects a misregistration detection toner mark 115. These sensors 116 are arranged in a direction (main scanning direction) orthogonal to the moving direction of the transfer conveyance belt 21.

  In FIG. 7, the number of sensors 116 is three, but it is essential to provide at least two sensors. In this case, it is preferable to dispose them at positions close to both ends of the transfer conveyance belt 21. The misregistration detection toner mark 115 is formed at a position facing the sensor 116. When three sensors 116 are provided as shown in FIG. 7, the positional deviation detection toner mark 115 is formed opposite to the two sensors 116 at both ends according to the required adjustment accuracy, and three sensors 116 are provided. It is possible to select the case where the misalignment detection toner mark 115 is formed corresponding to all of the sensors 116.

  FIG. 8 is a diagram illustrating a configuration of the sensor 116. The sensors 116 respectively receive a light emitting element 117 that irradiates the transfer / conveyance belt 21, a slit plate 118 in which a slit 118a through which light reflected by the transfer / conveyance belt 21 passes, and a light reception that receives light that has passed through the slit 118a. An element 119 is included. The light receiving element 119 is connected to an information processing unit 120 that processes a signal from the light receiving element 119 to be described later. In this embodiment, since the transfer conveyance belt 21 formed of a transparent material is used, the light emitting element 117 and the light receiving element 119 are arranged at a position sandwiching the transfer conveyance belt 21. When the transfer conveyance belt 21 is not transparent, the slit plate 118 and the light receiving element 119 are disposed on the same side as the light emitting element 117, and the light reflected by the surface of the transfer conveyance belt 21 passes through the slit 118a and passes through the light receiving element 119. Are configured to receive light.

  Next, the shape of the misregistration detection toner mark 115 and the slit 118a provided in the slit plate 118 will be described. FIG. 9 is a diagram showing the shape of the slit 118a, and FIG. 10 shows the positional relationship between the misalignment detection toner mark 115 formed on the transfer / conveying belt 21 and the slit 118a. The misregistration detection toner mark 115 is formed on the transfer conveyance belt 21 at a position facing each sensor 116, and is a linear toner mark (hereinafter, also referred to as “horizontal line mark”) parallel to the main scanning direction. It is composed of linear toner marks (hereinafter also referred to as “oblique line marks”) that are inclined with respect to the horizontal line marks. In the misregistration detection toner mark 115, K, C, M, and Y mean that they are formed of black toner, cyan toner, magenta toner, and yellow toner, respectively.

  As shown in FIG. 9, the slit 118 a is a portion formed in the same direction as the horizontal line mark in the misregistration detection toner mark 115 and a portion formed in the same direction as the oblique line mark in the misregistration detection toner mark 115. It is formed in the shape of x which has. The slit 118a has a width dimension of “a” and a length dimension of “b”. The width dimension of the misregistration detection toner mark 115 is formed to be the same as the width dimension “a” of the slit 118a, and the length dimension of the misregistration detection toner mark 115 is larger than the length dimension “b” of the slit 118a. It is formed long.

  As the transfer / conveying belt 21 moves in the sub-scanning direction, each misregistration detection toner mark 115 sequentially passes through a position facing the slit 118a. The light receiving element 119 receives the light from the transparent transfer conveyance belt 21 as it is when the misregistration detection toner mark 115 is not formed, and the misregistration detection toner mark 115 is positioned at the position of the slit 118a. , The light shielded by the misregistration detection toner mark 115 is received. Therefore, the output timing of the light receiving element 119 is processed by the information processing unit 120 in a time series, whereby the passing timing of the misregistration detection toner mark 115 is known, and the misregistration detection toner mark between the colors on the transfer conveyance belt 21 is obtained. 115 intervals can be known. Then, the registration deviation in the sub-scanning corresponding direction in the case of the position characteristic A described above can be detected by the detection signal of the horizontal line mark. Further, by combining the detection signals of the two horizontal line marks formed on the same main scanning line, it is possible to detect the sub-scan corresponding direction scanning line inclination shift in the case of the position characteristic B. In addition, a main-scan-corresponding direction registration shift in the case of the position characteristic D and a main-scan corresponding direction magnification shift in the case of the position characteristic E can be detected by the detection signal of the oblique line mark.

  Here, the configuration of the information processing unit 120 will be described in detail. FIG. 11 is a diagram illustrating a configuration of the information processing unit 120. The detection signal obtained from the light receiving element 119 is amplified by an AMP (amplifier) 121, and only the signal component of the misregistration detection toner mark 115 is passed by the filter 122. The A / D converter 123 converts the signal from analog data to digital data. Converted to. Sampling of data is controlled by the sampling control unit 124, and the sampled data is stored in the FIFO memory 125. After the detection of the misalignment detection toner mark 115 is completed, the data stored in the FIFO (First In First Out) memory 125 is loaded to the CPU 128 and the RAM 129 via the I / O port 126 via the data bus 127. Appropriate arithmetic processing is performed to obtain various amounts of deviation. Then, arithmetic processing for eliminating the deviation amount is performed, and the result of the arithmetic processing is stored in the RAM 129. At the time of image formation, image formation is controlled based on the result of the arithmetic processing. The ROM 130 stores various programs including a program for calculating the deviation amount. A ROM address, a RAM address, and various input / output devices are designated by the address bus 131. Further, the CPU 128 monitors the detection signal from the light receiving element 119 at an appropriate timing, and controls the light emission amount so that it can be reliably detected even if the transfer / conveying belt 21 and the light emitting element 117 are deteriorated. The level of the light reception signal from the light receiving element 119 is always constant.

  Next, a procedure for adjusting the positional deviation of the toner image will be specifically described. FIG. 12 is a flowchart for explaining the misalignment adjustment processing caused by the misalignment of the scanning line in the sub-scanning corresponding direction in the case of the above-described position characteristic B. When the adjustment process is started, first, a reference color misregistration detection toner mark 115 and other color misregistration detection toner marks 115 are provided for each position facing the sensors 116 at both ends shown in FIG. It is formed on the transfer conveyance belt 21 (step S-B1). These misregistration detection toner marks 115 are detected by the sensor 116, and other positions for the reference color are detected for each position of the sensor 116 (position of the sensor 116 along the main scanning corresponding direction) according to the detection result. A color misregistration amount in the sub-scanning corresponding direction is detected (step S-B2), and a function of misregistration amount detection, which is one of the functions of the information processing unit 120, is executed here. Next, the amount of inclination with respect to the reference color is calculated from the amount of misalignment detected at the position of each sensor 116 (step S-B3), and calculation, which is one of the functions of the information processing unit 120, is executed here. The

  FIG. 13 is a flowchart for explaining the misregistration amount calculation process caused by the main-scan corresponding direction registration deviation in the case of the position characteristic D and the main scan-corresponding direction magnification deviation in the case of the position characteristic E. When the misregistration amount calculation processing is started, first, the misregistration detection toner mark 115 of the reference color and the misregistration detection toner marks 115 of other colors are transferred to the transfer conveyance belt for each position facing the sensors 116 at both ends. (Step S-ED1). These misregistration detection toner marks 115 are detected by a sensor 116, and other color of the reference color is detected for each position of the sensor 116 (position of the sensor 116 along the main scanning direction) according to the detection result. A displacement amount in the main scanning direction is detected (step S-ED2), and a displacement amount detection function, which is one of the functions of the information processing unit 120, is executed here. Next, the pixel clock to be corrected is calculated from the amount of positional deviation detected at the position of each sensor 116 (step S-ED3), and further, the positional deviation when the pixel clock to be corrected is reflected is corrected. The shift amount is calculated, and an operation that is one of the functions of the information processing unit 120 is executed.

  Next, FIG. 14 is a flowchart for explaining the positional deviation amount calculation processing caused by the deviation in scanning speed uniformity in the main scanning corresponding direction in the case of the positional characteristics F described above. When the misregistration amount calculation processing is started, first, the misregistration detection toner mark 115 of the reference color and the misregistration detection toner marks 115 of other colors are transferred and conveyed for each position facing the three sensors 116. Formed on the belt 21 (step S-F1). Then, the position detection toner mark 115 is detected by the sensor 116, and another color with respect to the reference color is determined for each position of the sensor 116 (position of the sensor 116 along the main scanning corresponding direction) according to the detection result. The positional deviation amount in the main scanning correspondence direction is detected (step S-F2), and here, the positional deviation amount detection function which is one of the functions of the information processing unit 120 is executed. Next, the scanning speed uniformity deviation amount with respect to the reference color is calculated from the positional deviation amounts detected by the sensors 116 (step S-F3), and this is one of the functions of the information processing unit 120. Is executed.

  Therefore, by correcting the conversion table by the information processing unit 120 based on the positional deviation amount calculated by the positional deviation amount calculation processing, even if the positional deviation is corrected by the positional deviation prediction, it is related to the use state of the apparatus main body. And proper misalignment correction can be performed.

As described above, according to the present embodiment, the plurality of photosensitive drums 5Y, 5M, 5C, and 5Bk, which are a plurality of image carriers, and the plurality of driving units that respectively drive the plurality of photosensitive drums 5Y, 5M, 5C, and 5Bk. A plurality of drum motors, a developing device 9 as toner image forming means for forming toner images of different colors on the plurality of photosensitive drums 5Y, 5M, 5C, and 5Bk, and the photosensitive drum 5. The image forming apparatus includes a transfer unit that superimposes toner images and finally transfers the toner image onto a recording sheet that is a recording medium, and a fixing device that is a fixing unit that fixes the toner image on the recording sheet onto the recording sheet by applying at least heat. In the image forming apparatus, there is misregistration amount prediction information acquisition means for acquiring misregistration prediction information for predicting misregistration of each color toner image on the transfer body, and based on the misregistration amount prediction information. And an information processing unit 120 that is also a position deviation prediction unit that performs position deviation prediction, and a control unit that is a control unit that controls driving of each of the plurality of drum motors based on a prediction result of the position deviation prediction unit. ing. Thus, the photosensitive drums 5Y and 5M are configured to correct the positional deviation of the toner image in accordance with the positional deviation amount predicted by the information processing unit 120 from the positional deviation prediction information at the time of toner image formation in which the positional deviation correction is performed. , 5C, and 5Bk are controlled by the control unit so that the image forming position on each of the photosensitive drums 5Y, 5M, 5C, and 5Bk can be adjusted, so that the positional deviation of the toner image can be corrected.
Further, according to the present embodiment, the positional deviation amount prediction information includes an elapsed time from the time when the fixing device 10 is heated. Thus, when the information processing unit 120 acquires the elapsed time from the start of heating or the stop of heating of the heater 15 as the positional deviation prediction information, the elapsed time based on the conversion table corresponding to the case where the heat source is the heater 15. It is possible to calculate the amount of misalignment corresponding to the above and predict the amount of misregistration.
In addition, according to the present embodiment, the double-sided device 90 that is a recording body reversing unit that reverses the front and back of the recording paper is provided, and the positional deviation amount prediction information includes a progress from the start of operation of the double-sided device 90. This includes the time or the elapsed time from when the image has been formed on both sides of the recording paper. Accordingly, the information processing unit 120 fixes the image on one side by the fixing device 10 and forms an image on both sides of the recording paper when the recording paper having heat is formed again on the other side. When the elapsed time after the acquisition is acquired, the amount of misregistration corresponding to the elapsed time is calculated based on the conversion table corresponding to the case where the heat source is heated at the time of fixing, and the misregistration amount is predicted. Can do.
Further, according to the present embodiment, the positional deviation amount prediction information includes an elapsed time from the time when the operation state of the drum motor is changed. As a result, when the information processing unit 120 acquires the elapsed time from the start or stop of driving of the drum motor, which is positional deviation prediction information, the elapsed time based on the conversion table corresponding to the case where the heat source is the drum motor. It is possible to calculate the amount of misalignment corresponding to the above and predict the amount of misregistration.
Further, according to the present embodiment, the optical scanning device 8 which is a latent image writing unit for writing a latent image on the photosensitive drum 5 is provided, and the positional deviation amount prediction information includes the operation of the optical scanning device 8. The elapsed time from the point of state change is included. As a result, when the information processing unit 120 acquires the elapsed time from when the polygon motor 62c provided in the optical scanning device 8 is operated or stopped, which is positional deviation prediction information, when the heat source is the polygon motor 62c. Based on the corresponding conversion table, the positional deviation amount corresponding to the elapsed time can be calculated, and the positional deviation amount can be predicted.
Moreover, according to this embodiment, it has the temperature sensor 150 which is a temperature detection means which detects use environment temperature. As a result, when the information processing unit 120 predicts misalignment, an appropriate misalignment correction can be performed regardless of the use environment temperature by using the conversion table corresponding to the use environment temperature. It should be noted that a configuration for correcting misregistration based on the detection result of the temperature sensor 150 may be adopted.
Further, according to the present embodiment, at least the RAM 129 serving as information storage means for storing conversion information that is information for converting the positional deviation amount prediction information into the positional deviation amount, and a position for detecting the positional deviation of the toner image. A sensor 116 serving as a deviation detection unit and a conversion information correction unit that corrects the conversion information based on the detection result of the sensor 116 are provided. Thus, even if the position deviation is corrected by the position deviation prediction by performing the position deviation amount calculation process from the detection result of the sensor 116 and correcting the conversion table based on the calculated position deviation amount, Appropriate misalignment correction can be performed regardless of the state of use.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. The top view of an optical scanning device. Sectional drawing of the A-A 'line part in an optical scanning device. FIG. 3 is a schematic diagram of positional deviation of an actual image with respect to an ideal position. The time-position shift amount relationship diagram at the time of heater operation. The time-position shift amount relationship diagram at the time of a heater stop. FIG. 3 is a configuration diagram of a mechanism for detecting a positional deviation of a toner image. The block diagram of a sensor. The schematic block diagram of a slit. The positional relationship between the misalignment detection toner mark and the slit. The schematic block diagram of an information processing part. 10 is a flowchart of misregistration adjustment processing caused by sub-scanning corresponding direction scanning line tilt misalignment. 10 is a flowchart of misregistration amount calculation processing caused by main-scan corresponding direction registration shift and main-scan corresponding direction magnification shift. 6 is a flowchart of misregistration amount calculation processing caused by a deviation in scanning speed uniformity in the main scanning correspondence direction.

Explanation of symbols

5 Photosensitive drum 15 Heater 40 Re-carrying unit 62c Polygon motor 90 Double-sided device 118 Slit plate 120 Information processing unit 129 RAM
150 Temperature sensor

Claims (8)

An image carrier;
Drive means for driving the image carrier;
Toner image forming means for forming a toner image on the image carrier;
Transfer means for finally transferring the toner image formed on the image carrier onto a recording medium;
In an image forming apparatus comprising: a fixing unit that fixes the toner image on the recording body on the recording body by applying at least heat;
Misregistration amount prediction information acquisition means for acquiring misregistration amount prediction information, which is information for predicting the misregistration amount of the toner image;
A misregistration amount prediction means for predicting the misregistration amount based on the misregistration amount prediction information;
An image forming apparatus comprising: a drive control unit that controls driving of the driving unit so as to correct the positional deviation amount according to a prediction result of the positional deviation amount prediction unit. A plurality of image carriers;
A plurality of driving means for respectively driving the plurality of image carriers;
Toner image forming means for forming toner images on the plurality of image carriers;
Transfer means for superimposing the toner images formed on the plurality of image carriers and finally transferring the toner images onto a recording medium;
In an image forming apparatus comprising: a fixing unit that fixes the toner image on the recording body on the recording body by applying at least heat;
Misregistration amount prediction information acquisition means for acquiring misregistration amount prediction information, which is information for predicting the misregistration amount of the toner image;
A misregistration amount prediction means for predicting the misregistration amount based on the misregistration amount prediction information;
An image forming apparatus comprising: a drive control unit that controls each of the plurality of drive units so as to correct the position shift amount according to a prediction result of the position shift amount prediction unit. The image forming apparatus according to claim 1 or 2,
The image forming apparatus according to claim 1, wherein the misregistration amount prediction information includes an elapsed time from when the fixing unit is heated. The image forming apparatus according to claim 1, 2 or 3.
It has a recording body inversion means for inverting the front and back of the recording body,
The positional deviation amount prediction information includes an elapsed time from the start of operation of the recording medium reversing unit, or an elapsed time from the end of image formation on both sides of the recording body. Image forming apparatus. The image forming apparatus according to claim 1, 2, 3, or 4.
2. The image forming apparatus according to claim 1, wherein the positional deviation amount prediction information includes an elapsed time from the driving state change time of the driving unit. The image forming apparatus according to claim 1, 2, 3, 4, or 5.
It has a latent image writing means for writing a latent image on the image carrier,
2. The image forming apparatus according to claim 1, wherein the positional deviation amount prediction information includes an elapsed time from when the latent image writing unit is turned on or an elapsed time from when the latent image writing unit is turned off. The image forming apparatus according to claim 1, 2, 3, 4, 5 or 6.
It has a temperature detection means to detect the operating environment temperature,
The image forming apparatus, wherein the positional deviation amount prediction information includes a detection result of the temperature detecting means. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6 or 7.
At least information storage means for storing conversion information which is information for converting the positional deviation amount prediction information into the positional deviation amount;
A misregistration detecting means for detecting misregistration of the toner image;
An image forming apparatus comprising: a conversion information correction unit that corrects the conversion information based on a detection result of the position deviation detection unit.

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