JP2011068065A - Image controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control belt moving speed more accurately by eliminating an error caused by the uneven thickness of a belt and the eccentricity of a roller shaft which have been superposed on the measured belt moving speed. <P>SOLUTION: An image controller includes a speed ratio operating section 401 which has a laser Doppler velocimeter 311 and a following side encoder 310 which detect the moving speed of a conveyance belt 160 and the rotational angular rate of a following roller while extracting belt profile data and roller profile data from the measured speed ratio, and a correction control section 331 which controls the timing of each image formation with a head unit 110 so that positional deviation between a plurality of images arising on the conveyance belt 160 may become small based on each profile data. These profiles are formed by performing Fourier transform, eliminating a predetermined frequency from the result from the Fourier transform so as to be an effective degree according to the characteristics of the roller, and then performing inverse Fourier transform. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus, and more particularly to an image control apparatus that controls image formation.

  2. Description of the Related Art Conventionally, there is a printing apparatus including a conveyance mechanism that conveys a recording sheet using an endless conveyance belt. In this printing apparatus, a recording sheet is transported using a transport belt, and is sequentially passed through a plurality of ink heads that form different monochrome images arranged along the transport direction. Thereby, it is possible to obtain a color image by superimposing the single color images on the recording paper.

  By the way, since high-precision drive control for moving the conveyor belt at a constant movement speed is required, conventionally, a drive for controlling the rotation of the drive roller as a mechanism for keeping the rotation speed of the drive roller for driving the belt constant. A control method is known. As this drive control method, the rotational speed of the driving roller is kept constant by maintaining the rotational angular speed of the motor that is the driving source and the rotational angular speed of the gear that transmits the rotational driving force generated by the motor to the driving roller. There is something to do.

  However, there is a problem in that there is belt thickness unevenness in the belt circumferential direction, and the belt moving speed changes due to this unevenness. This belt thickness unevenness is caused, for example, by uneven thickness in the belt circumferential direction seen in a belt produced by a centrifugal firing method using a cylindrical mold, and such belt thickness unevenness exists in the belt. When the thick belt part is wound on the driving roller that drives the belt, the belt moving speed is fast. On the other hand, when the thin belt part is winding, the belt moving speed is slow, and the belt moving speed fluctuates. Will occur.

  Thus, if the moving speed of the conveying belt is not maintained at a constant speed, when a single color image is formed on a recording sheet by a plurality of ink heads and these colors are superimposed, the transfer position of each single color image is relative. A so-called “landing deviation” occurs. When such landing misalignment occurs, for example, a fine line image formed by overlapping a plurality of color images looks blurred, or a black character image formed in a background image formed by overlapping a plurality of color images White spots may occur around the outline of the.

  In order to prevent such landing deviation, there is a technique described in Patent Document 1, for example, as a technique for reducing belt speed fluctuation. In the technique disclosed in Patent Document 1, a thickness profile (belt thickness unevenness) in the entire circumference of the belt is measured in advance, and the thickness profile data is stored in a data storage unit. The printing timing is changed so that the phase with the actual belt thickness unevenness is matched and the printing position deviation due to belt speed fluctuation does not occur.

  More specifically, in the technique disclosed in Patent Document 1, the rotation having a frequency corresponding to the belt speed fluctuation is obtained from the difference data of the rotational angular velocities of the two rollers (the driving roller and the driven roller) on which the conveyance belt is stretched. Extract AC component of angular velocity, recognize belt speed fluctuation due to belt thickness unevenness from extracted AC component amplitude and phase data, and start image formation for each of multiple images based on the recognized belt speed fluctuation The timing and the image forming speed during image formation are adjusted.

JP 2006-227192 A

  However, in the technique disclosed in Patent Document 1, the correction data of the speed fluctuation of the conveyor belt has an enormous amount of data, which increases the burden of arithmetic processing and may cause processing delay. In addition, there is a problem that the amount of memory used for storing correction data increases. As a result, high-performance parts / devices are required to manufacture the printing apparatus, and the manufacturing cost increases.

  Further, when the correction data is stored as it is, the data includes vibration of a driving portion such as a motor of a driving roller as noise, and this is reflected in the data as belt speed fluctuation. Therefore, when the correction data is created in a state in which these noises are included, the accuracy of the belt speed fluctuation control is reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to profile belt thickness unevenness data and roller shaft eccentricity data in a printing apparatus having a conveyance mechanism that conveys paper by a conveyance belt. When adjusting the printing timing, the amount of information of these profiles can be reduced, the processing speed can be increased, the manufacturing cost can be reduced, and the noise included in the profile data can be reduced. Another object of the present invention is to provide an image control apparatus for a printing apparatus that can control the belt moving speed with higher accuracy.

  In order to solve the above-described problems, the present invention provides an endless transport belt that is stretched between a plurality of support rollers, a drive unit that moves the transport belt endlessly, and a plurality of images on a recording sheet on the transport belt. An image control apparatus for controlling image formation in a printing apparatus having a plurality of ink heads formed so as to overlap with each other, the temporal ratio of a speed ratio between a support roller and an arbitrary measurement point on a conveyor belt A belt profile storage unit that stores speed ratio data having a frequency corresponding to the speed ratio as a belt profile from fluctuations, and a roller profile that stores temporal fluctuations in the belt feed speed ratio caused by the eccentricity of the support roller as a roller profile. Based on the storage unit, belt profile and roller profile, on the conveyor belt Print control means for controlling the timing of each image formation by the ink head so that the positional deviation between a plurality of images is small, and the belt profile and roller profile are temporal variations of the speed ratio data and the belt feed speed ratio. Is generated by removing a predetermined frequency from the result of the Fourier transform so that the effective order according to the characteristics of the belt and the support roller is obtained, and further performing an inverse Fourier transform.

  According to the present invention as described above, unevenness information of the conveyance belt and eccentricity information of the support roller are stored and held as profiles, and this is controlled by controlling the timing of image formation by the ink head, thereby reducing landing deviation. The image quality can be improved. In particular, according to the present invention, the profile data size can be reduced because the profile is Fourier-transformed and noises of frequencies higher than the effective order are eliminated by filtering. Here, the eccentric information of the support roller is information on the speed fluctuation caused by the eccentricity, and corresponds to the eccentricity of the support roller from the temporal fluctuation of the moving speed at each measurement point in addition to the temporal fluctuation of the belt feed speed ratio. Information having such a frequency is also included, and this information may be stored and held as a profile.

  In the above invention, the characteristics of the support roller include a cycle of the support roller and a reduction ratio between the support roller and the drive shaft that drives the support roller, and the constant of the roller cycle is obtained with respect to the Fourier transformed result. It is preferable to delete frequencies outside the range of the effective order so that the effective order is up to double or a value obtained by dividing the reduction ratio by the noise frequency. In the above invention, the constant is preferably 5, and the reduction ratio is preferably 5 or more.

  In this case, by applying the correlation between the rotation period of the support roller, the reduction ratio with respect to the drive shaft and the frequency of noise, and the effective order at the time of filtering, the drive source and its The data size can be reduced by effectively reducing noise from a drive source or the like. Here, the drive shaft includes a rotation shaft of a drive motor as a drive source, and a rotation shaft of a drive system element such as a gear and a pulley for transmitting a drive force from the drive motor. Therefore, regarding the speed ratio between the support roller and the drive shaft, whether the reference on the drive side is a gear directly connected to the support roller or the drive motor that is the origin of the drive force is subject to filtering. It is preferable to select appropriately according to the noise generation source (generation position). For example, if noise is generated from the drive motor, the reference point of the drive side speed is the rotation axis of the drive motor, and if noise is generated from drive system elements such as gears and pulleys, specify that The speed ratio with the support roller is obtained as the rotation axis of the drive system element (for example, the gear at the final stage).

  In the above invention, the characteristics of the belt include a belt cycle and a reduction ratio between the belt and a support roller that drives the belt. For a result of Fourier transform, a result of Fourier transform is obtained. It is preferable to delete frequencies outside the range of the effective order so that the effective order is a value obtained by dividing the belt period by a constant multiple or the reduction ratio by the noise frequency. In the above invention, the constant is preferably 5, and the reduction ratio is preferably 5 or more.

  In this case, by applying the correlation between the rotation period of the conveyor belt, the reduction ratio with respect to the support roller and the frequency of the noise, and the effective order at the time of filtering, from the driving source etc. without losing the accuracy of the profile The noise can be effectively reduced to reduce the data size.

  That is, the inventors of the present invention relate to the noise reduction of the profile in which the thickness unevenness of the transport belt and the eccentricity of the support roller calculated based on the fluctuation of the transport speed of the transport belt are recorded, and the cycle of the transport belt and the support roller. The correlation between the effective order or the correlation between the reduction ratio (support roller: drive motor and transport belt: support roller), noise frequency, and effective order was discovered and applied to the image control device of the printing apparatus. The present invention.

  In the frequency analysis after Fourier transform, the effective data of the unevenness of the conveying belt is the 0th order (not shown) representing the speed of the belt itself, the first to fifth orders of thickness unevenness, and the seventh order which is a frequency component higher than that. Has a low contribution to approximating belt thickness unevenness, and a frequency component higher than the 8th order which is the period of the driving roller includes noise such as eccentricity of the driving roller.

  The effective data contributing to the correction of the eccentricity of the roller profile is the 8th to 40th order (the belt is one turn for the belt, the effective order is the 5th order as shown below), and the 48th order is the contribution to the correction. The 48th and higher order motors have a lot of driving noise. Considering the reduction ratio, it has been found that the frequency component of the motor with respect to the roller is 8/8 to 40/8 = 1-order to fifth-order, and that the fifth-order as in the case of the belt is effective, the accuracy is sufficient. Therefore, in the present invention, the effective order after the Fourier transform is set to a constant multiple of the roller period and the reduction ratio. In addition, as this constant multiple, when the support roller makes eight revolutions with respect to one rotation of the belt, 5 to 7 times is optimal together with the period of the support roller and the reduction ratio, and the contribution to the 7th order accuracy is small. Since this was experimentally understood, the fifth order was adopted.

  As described above, according to the present invention, in a printing apparatus equipped with a conveyance mechanism that conveys a sheet by a conveyance belt, belt thickness unevenness data and roller shaft eccentricity data are used as profiles, and printing timing is set. At the time of adjustment, these profiles can be Fourier transformed and filtered to reduce the amount of correction data, speed up the calculation process, reduce manufacturing costs, and eliminate noise contained in the correction data. In addition, the belt moving speed can be controlled with higher accuracy.

It is a block diagram which shows the outline | summary of the conveyance path | route of the printing apparatus which concerns on embodiment. It is a functional block diagram which shows the module regarding the discharge timing control of the head unit 110 which concerns on embodiment. In an embodiment, it is a functional block diagram showing the relation between the processing in the arithmetic processing unit and the printing / conveying drive unit in the printing apparatus. It is a functional block diagram which shows the module regarding the profile generation which concerns on embodiment. It is explanatory drawing which shows typically the function and operation | movement of profile generation which concern on embodiment. It is explanatory drawing regarding correction | amendment of an encoder signal at the time of controlling the discharge timing of the ink which concerns on embodiment. It is a flowchart figure which shows the procedure at the time of the production | generation of the profile data which concerns on embodiment. It is a graph showing the speed ratio data which has a frequency corresponding to the speed fluctuation which concerns on embodiment. It is a flowchart figure which shows the procedure of the correction process with respect to the speed ratio accumulation data which concerns on embodiment. It is a graph which shows accumulation data calculation with respect to the speed ratio which concerns on embodiment.

(Overall configuration of printing device)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a diagram illustrating an outline of a conveyance path of the printing apparatus 100 according to the present embodiment. In this embodiment, the printing apparatus 100 includes a plurality of ink heads on which a large number of nozzles are formed, discharges black or color ink from each ink head, performs printing in line units, and prints on a recording medium on a conveyance belt. An ink-jet line color printer that forms a plurality of images so as to overlap each other will be described as an example.

  As shown in FIG. 1A, the printing apparatus 100 is an apparatus that forms an image on the surface of a recording medium conveyed on an annular conveyance path, and the conveyance path is a paper feed system conveyance path FR that supplies the recording medium. And a normal path CR from the paper feed system conveyance path FR through the head unit 110 to the paper discharge path DR, and a reverse path SR branched and connected to the normal path CR.

  In the paper feed system conveyance path FR, as a paper feed mechanism for supplying the recording medium, a side paper feed stand 120 disposed outside the side surface of the housing and a plurality of paper feed trays (inside the housing) 130a, 130b, 130c, 130d). In addition, a paper discharge port 140 is provided as a paper discharge mechanism for discharging the printed recording medium.

  The recording medium fed from one of the side paper feed tray 120 and the paper feed tray 130 is transported along a paper feed system transport path FR in the housing by a driving mechanism such as a roller, and the recording medium It is guided to the resist portion R which is the reference position of the head portion. A head unit 110 including a plurality of ink heads is provided further on the registration direction R in the transport direction side. The recording medium is image-formed line by line with ink ejected from each ink head while being conveyed at a speed determined by printing conditions by a conveying belt 160 provided on the opposite surface of the head unit 110.

  The printed recording medium is further conveyed on the normal route CR by a driving mechanism such as a roller. In the case of single-sided printing in which printing is performed only on one side of the recording medium, the paper is directly discharged to the paper discharge port 140 through the paper discharge path DR, and is discharged as a tray for the paper discharge port 140. It is loaded on the table 150 with the printing surface facing down. The paper discharge table 150 has a tray shape protruding from the housing, and has a certain thickness. The sheet discharge table 150 is inclined, and the recording medium discharged from the sheet discharge port 140 is naturally arranged and overlapped by a wall formed at a position below the inclination.

  On the other hand, in the case of double-sided printing in which printing is performed on both sides of the recording medium, the front surface (the first printed surface is “front surface” and the next printed surface is “back surface”). Without being guided to the side, it is further transported in the housing and sent out to the reversing path SR. For this reason, the printing apparatus 100 is provided with a switching mechanism 170 for switching the transport path for backside printing, and the recording medium that has not been sent to the discharge path by the switching mechanism 170 is drawn into the reversing path SR.

  In the reversal path SR, the recording medium is delivered from the normal path CR, and so-called switchback is performed in which the recording medium is reversed by reciprocating the recording medium. Then, it is returned to the normal route CR via the switching mechanism 172 by a driving mechanism such as a roller, is fed again through the registration portion R, and the back side is printed by the same procedure as the front side. Thereafter, the recording medium on which the back side is printed and images are formed on both sides is guided to the paper discharge port 140 through the paper discharge route DR and discharged, and the paper discharge is provided as a receiving base of the paper discharge port 140. It is loaded on the table 150.

  In the present embodiment, switchback at the time of duplex printing is performed using a space provided in the paper discharge tray 150. The space provided in the paper discharge tray 150 is configured to be covered so that the recording medium cannot be removed from the outside during switchback. As a result, it is possible to prevent the user from accidentally pulling out the recording medium during the reversing operation. Further, the paper discharge tray 150 is originally provided in the printing apparatus 100, and by performing switchback using the space in the paper discharge tray 150, a separate switchback is provided in the printing apparatus 100. There is no need to provide space. Therefore, an increase in the size of the housing can be prevented. Furthermore, since the paper discharge path and the reverse path are not shared, the switchback process and the discharge of other recording media can be performed in parallel.

  In the printing apparatus 100, the recording medium that has been printed on one side is also re-fed to the registration portion R that is the reference position of the leading portion of the fed recording medium. For this reason, a junction point where the conveyance path of the newly fed recording medium and the refeed path where the recording medium for backside printing is circulated is merged is formed immediately before the registration portion R. Is done. Then, the registration unit R sends out the recording medium in the vicinity of the merging point between the paper feeding system conveyance path FR and the normal path CR.

  In the present embodiment, the path on the sheet feeding mechanism side is defined as the sheet feeding system conveyance path FR, and the other paths are defined as the conveyance paths based on the merging point. This transport path is annular, and includes the normal path CR and the reverse path SR as described above. FIG. 1B is a diagram schematically showing the sheet feeding system conveyance path FR, the normal path CR, and the reverse path SR. In the figure, the number of rollers constituting the drive unit is omitted as appropriate.

  In the paper feed system conveyance path FR, the side paper feed driving unit 220 for feeding paper from the side paper feed tray 120 and the paper feed from the paper feed trays 130 (130a, 130b, 130c, 130d) are provided. A tray 1 driving unit 230a, a tray 2 driving unit 230b,. Thus, a sheet feeding unit for feeding the recording medium to the registration unit R is configured.

  Further, any of the driving units (tray 1 driving unit 230a, tray 2 driving unit 230b...) In the above-described paper feeding system conveyance path FR includes a driving mechanism composed of a plurality of rollers or the like. Are taken one by one and conveyed in the direction of the registration portion R. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with a paper feed mechanism that feeds paper.

  In addition, a plurality of transport sensors are arranged in the paper feed system transport path FR so that a transport jam in the paper feed system transport path FR can be detected. That is, each conveyance sensor is a sensor that detects the presence or absence of a recording medium or the leading edge of the recording medium. For example, a plurality of conveyance sensors are arranged at appropriate intervals on a conveyance path, and a conveyance sensor provided on the paper feeding side is provided. If the conveyance sensor on the conveyance direction side does not detect the recording medium within a predetermined time after detecting the recording medium, it can be determined that a conveyance jam has occurred.

  Among these conveyance sensors, a registration sensor in front of the registration unit R that sends out the recording medium measures the size of the recording medium being conveyed, and, for example, the recording medium being passed based on the passing speed and the passing time of the recording medium. When a conveyance sensor does not detect a recording medium within a predetermined time after measuring the size of the paper or driving the side paper feed drive unit 220, the tray 1 drive unit 230a, etc., a paper jam (paper feed error) has occurred. It can be judged.

  The normal path CR forms a part of the circulation transport path, and is a path from the paper feed transport path FR that supplies the recording medium to the paper discharge path DR through the head unit 110, and the recording is performed on the normal path CR. An image is formed on the upper surface of the medium. In this normal path CR, a registration driving unit 240 that guides the recording medium to the registration unit R, a driving motor 250 that drives the endless movement of the conveyance belt 160 provided on the opposite surface of the head unit 110, and a conveyance direction side in order. The first upper surface transport driving unit 260 and the second upper surface transport driving unit 265, the upper surface discharge driving unit 270 that guides the printed recording medium to the paper discharge port 140, and the drive for drawing the recording medium into the reverse path SR for back surface printing. Means are provided. Each drive unit includes a drive mechanism composed of one or a plurality of rollers or the like, and conveys the recording medium one by one along the conveyance path. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with the conveyance status of the recording medium.

  In addition, a plurality of transport sensors are arranged on the normal route CR so that a transport jam in the normal route CR can be detected. Further, it is possible to confirm that the recording medium is appropriately conveyed also in the resist portion R. In the normal route CR, a conveyance sensor is provided corresponding to the drive unit, and it is possible to specify in which drive unit of the normal route CR the conveyance jam has occurred.

  The reversing path SR is branched and connected to the normal path CR, the recording medium is transferred from the normal path CR, and the recording medium is reciprocated (switched back) to return to the normal path CR to reverse the front and back of the recording medium. The reversing path SR is provided with a reversing drive unit 281 and a refeed driving unit 282 for reversing the recording medium and leading it to the junction. The reversing path SR can be transported at a speed different from that of the normal path CR, and when taking over the recording medium from the normal path CR, it is accelerated or decelerated, and the stop time at the time of switchback is extended or shortened. Can be.

  In the present embodiment, after a certain recording medium is fed, the next recording medium is not fed after waiting for the recording medium to be printed and discharged. Before the recording medium is discharged, the subsequent recording medium is fed and can be continuously printed at a predetermined interval. Therefore, in normal scheduling at the time of duplex printing, a space is secured in advance so as to secure a position where the recording medium returned from the reversing path SR is inserted when feeding the recording medium on the front surface. Thereby, in this apparatus, printing on the front surface and printing on the back surface can be performed in parallel, and half the productivity can be ensured with respect to single-sided printing.

  The conveyor belt 160 is wound around a driving roller 161 and a driven roller 162 disposed at the front end and the rear end of the surface facing the head unit 110, and rotates in the clockwise direction in FIG. . Further, on the upper surface of the transport belt 160, ink heads of four colors are arranged side by side along the belt moving direction, and a head unit 110 that forms a color image so as to overlap a plurality of images is opposed to the head unit 110. Yes.

  Furthermore, as illustrated in FIG. 1A, the printing apparatus 100 includes an arithmetic processing unit 330. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. Various functional modules are virtually constructed by appropriately reading and executing a program, and various functional modules for processing related to image data, operation control of each unit, and user operations are constructed by each constructed functional module. Process. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

(Discharge timing control)
Control of the ejection timing in the head unit 110 described above is also performed by the arithmetic processing unit 330. FIG. 2 is a functional block diagram illustrating modules relating to ejection timing control of the head unit 110 in the arithmetic processing unit 330. FIG. 3 illustrates processing in the arithmetic processing unit 330 and a printing / conveying drive unit in the printing apparatus 100. It is a functional block diagram which shows the relationship. The “module” used in the description refers to a functional unit that is configured by hardware such as an apparatus or a device, software having the function, or a combination thereof, and achieves a predetermined operation. .

  As shown in FIG. 2, the arithmetic processing unit 330 includes a correction control unit 331, a storage unit 332, a discharge control unit 333, a drive control unit 334, and a system control unit 335, and belt profile data. The roller profile data is transferred from the storage unit 332 to the correction control unit 331, and the correction control unit 331 corrects the output of the encoder.

  The storage unit 332 is a memory device that records generated belt profile data and roller profile data, and includes a storage memory 332b that stores belt profile data and a storage memory 332a that stores roller profiles. In the present embodiment, the belt profile data and the roller profile data are generated in advance by the external profile generation device 400 or the like, and are stored in the storage memories 332a and 332b by being installed at the time of factory shipment.

  Based on the belt profile data and roller profile data stored in the storage unit 332, the correction control unit 331 inputs from the driven encoder 310 so that the positional deviation between the plurality of images on the transport belt 160 is reduced. This is a module that corrects the detected signal and inputs it to each ejection control unit 333.

  In the present embodiment, the correction control unit 331 includes a belt profile correction control unit 331b and a roller profile correction control unit 331a. The belt profile correction control unit 331b is a module that corrects the detection signal from the driven encoder 310 based on the belt profile data, and corrects the speed fluctuation due to the uneven thickness component of the belt. On the other hand, the roller profile correction control unit 331a is a module that corrects the detection signal from the driven encoder 310 based on the roller profile data, and mainly corrects the speed fluctuation due to the eccentric information of the driven roller.

  In this embodiment, the driven roller is selected as the target of the roller profile in which the eccentric information of the support roller is recorded. However, other support rollers such as a drive roller can also be the target. In the present embodiment, the roller profile data is profile data that is the temporal variation of the belt feed speed ratio, which is eccentricity information. However, the eccentricity information includes information having a frequency corresponding to the eccentricity of the support roller. This information can be selected as a roller profile, and these two pieces of information can be included.

  The belt profile correction control unit 331b also receives a belt home position signal detected by the belt HP sensor 312 that detects one mark (reference mark) on one circumference of the belt, together with a detection signal from the driven encoder 310. Entered. On the other hand, the roller profile correction control unit 331a receives the detection signal corrected by the belt profile correction control unit 331b and the roller home position signal detected by the roller HP sensor 313 that detects one rotation of the roller. .

  The ejection control unit 333 is a print control unit that controls the timing of image formation by the head unit 110 based on the corrected detection signal. The head unit 110 performs recording according to the control by the ejection control unit 333. A plurality of images are formed on the medium 10.

  The system control unit 335 is a central processing unit that controls the operation of each module in the processing unit 330. In addition to image processing during printing, the system control unit 335 controls the operation of each driving unit in the transport path through the drive control unit 334. To do. The system control unit 335 also serves as a communication interface for communicating with the outside and an interface function for data transmission / reception with respect to the operation panel 340.

(Discharge timing control method during printing)
The ejection timing control using the profile data generated in this way is performed according to the following procedure. FIG. 3 is a block diagram schematically showing the operation during the printing process. Here, it is assumed that the roller profile data and the belt profile data are already stored in the storage memories 332a and 332b as independent profile data in the storage unit 332, respectively.

  First, when the printing process is started, the stored roller profile data and belt profile data are read from the storage memories 332a and 332b, respectively, and input to the correction control unit 331.

  Next, when the printing process is started, the angular velocity detected by the driven encoder 310 is input, the moving speed of the conveyor belt is measured (S201), and the discharge control of the head unit 110 is controlled based on the measurement result. Do. In this discharge control, the correction control unit 331 drives the driven side so as to reduce the positional deviation between the plurality of images on the conveyance belt 160 based on the roller profile data and the belt profile data stored in the storage unit 332. The encoder detection signal input from the encoder 310 is corrected (S202, S203) and input to the discharge control unit 333.

  In this correction, the correction value in the belt profile data is read in accordance with the rotation period of the conveyor belt 160 based on the home position signal, and the encoder detection input from the driven encoder 310 as shown in FIG. The signal is advanced or delayed according to the correction value, adjusted so that the positional deviation between the plurality of images on the conveyor belt 160 is reduced, and is input to the ejection control unit 333. The ejection control unit 333 controls the timing of image formation by the head unit 110 based on the corrected encoder detection signal (S204), and the head unit 110 ejects ink according to the control by the ejection control unit 333. Then, a plurality of images are formed on the recording medium.

  In this embodiment, in order to eliminate the landing deviation, it is necessary to calculate an absolute positional deviation based on the appropriate landing position as indicated by Δd in FIG. Since the instantaneous measurement value at is a relative speed fluctuation between these two measurement points, it is necessary to calculate an absolute speed fluctuation with respect to a predetermined reference point when correcting the landing deviation. In the present embodiment, the speed ratio between two measurement points at each time point is accumulated, and Δd, which is an absolute positional deviation at each time point, is stored in advance as a profile.

(Profile generator)
In the present embodiment, the belt profile data and roller profile data described above are generated using the profile generation device 400 and installed in the storage unit 332. FIG. 4 is an explanatory diagram showing a schematic configuration of the profile generation device 400. As shown in FIG. 4A, the profile generation device 400 is an external device that is temporarily connected to the printing device 100 when the printing device 100 is manufactured, before factory shipment, during maintenance, and the like. 400a and PC400b are roughly comprised.

  The LDV device 400a is a device that measures the moving speed of an object in a non-contact manner with a laser Doppler speedometer 311 that is a transport speed measuring means. The LDV apparatus 400a includes a laser Doppler speedometer 311 attached to the upper surface of the transport belt 160, and a driven A driven encoder 310 provided on the roller 162, a belt home position sensor 312 that detects one rotation of the conveyor belt 160, and a roller home position sensor 313 that detects one rotation of the driven roller 162 are connected to each other. The input signal is acquired and transferred to the PC 400b as the profile generation device while being synchronized.

  The PC 400b is an arithmetic processing unit provided with a CPU, and can be realized by a general-purpose computer such as a personal computer or a dedicated device specialized in functions. By executing software on the CPU, a profile data generation device Function as. Specifically, as shown in FIG. 4B, the PC 400 as the profile data generation apparatus includes a speed ratio calculation unit 401, a data processing unit 402, and a data memory 403.

  The speed ratio calculation unit 401 is a module that calculates the temporal variation of the speed ratio at each measurement point by the belt speed extraction unit 401b and the roller speed extraction unit 401a. Specifically, the belt speed extraction unit 401b and the roller speed The moving speed at any two measuring points on the belt is measured by the conveying speed measuring unit by the extracting unit 401a. In the present embodiment, the two arbitrary measurement points are the first measurement point and the second measurement point, and the movement speed of the first measurement point is the movement speed of the surface of the conveyance belt immediately below the center of the ink head. The second measurement point is the rotational speed (angular speed) of the driven roller 162.

  In this embodiment, the conveyance speed measuring means for the first measurement point is a non-contact measuring device that optically measures the movement speed of the conveyance belt surface. In this embodiment, the laser Doppler velocimeter 311 is provided. Use. The laser Doppler velocimeter 311 is a conveyance speed measurement unit that optically measures the moving speed of the surface of the conveyance belt 160. Specifically, the wavelength change between the incident light and the reflected light depends on the relative speed with respect to the object. The velocity of the object is measured by measuring The laser Doppler speedometer 311 is detachably provided to the printing apparatus 100. As a result, the laser Doppler velocimeter 311 can be installed only at the time of creating profile data, and the manufacturing cost can be reduced without incorporating an expensive measuring device in the image forming apparatus.

  On the other hand, the conveyance speed measuring means for the second measuring point uses a driven encoder 310 that measures the rotational speed of the driven roller 162. The belt speed extraction unit 401b and the roller speed extraction unit 401a extract the speed data of the conveyor belt and the roller from the moving speed measured by the laser Doppler velocimeter 311 and the detection signal of the driven encoder 310, respectively.

  In this embodiment, as shown in FIG. 4B, the detection signal from the laser Doppler velocimeter 311 and the detection signal from the driven encoder 310 are input to the speed ratio calculation unit 401. In addition, the speed ratio calculation unit 401 includes a belt HP sensor 312 that detects one mark (reference mark) around the belt and a roller HP sensor that detects one mark (reference mark) around the roller. Each home position signal detected at 313 is input.

  The speed ratio calculation unit 401 calculates the temporal variation of the speed ratio at each measurement point based on the moving speed of the surface of the conveyor belt detected by the laser Doppler speedometer 311 and the rotational angular speed detected by the driven encoder 310. The belt profile data and the roller profile data are extracted from the frequency corresponding to the calculated speed ratio.

  The data processing unit 402 is a module that performs processing such as averaging and digitization on the speed ratio data. The data memory 403 is a memory device that records pulse width data measured by the laser Doppler velocimeter 311 and a detection signal from the driven encoder 310 as speed data.

  In particular, in the present embodiment, the data processing unit 402 performs Fourier transform on the belt profile and roller profile described above with respect to the temporal variation of the speed ratio data and the belt feed speed ratio, and on the Fourier transformed data. A function of reducing the data size by performing filtering so as to obtain an effective order according to the characteristics of the driving roller 161 or the characteristics of the conveying belt 160, deleting a predetermined frequency, and further performing inverse Fourier transform have.

  As a characteristic of the driving roller 161 in filtering in the present embodiment, the period of the driving roller 161 and the speed ratio with the driving motor 250 are used, and the period of the driving roller 161 is a constant multiple of the Fourier transformed profile data. The frequency of the effective order or higher is deleted so that the effective order is within the range of the effective order and the range obtained by dividing the reduction ratio by the noise frequency. The constant multiple here is a numerical value “5” obtained experimentally.

  In addition, although the period of the driving roller 161 and the speed ratio with the driving motor 250 are used as the characteristics of the driving roller 161 in the present embodiment, only the speed ratio between the driving roller 161 and the driving motor 250 is used as this speed ratio. Without being limited, it is preferable to select a drive shaft included in the drive system in accordance with the generation source and frequency of the generated noise.

  The drive shaft includes a rotation shaft of a drive motor 250 that is a drive source, and a rotation shaft of a drive system element such as a gear and a pulley for transmitting a drive force from the drive motor 250. Therefore, regarding the speed ratio between the driving roller 161 and the driving shaft, whether the reference on the driving side is the gear directly connected to the driving roller 161 or the driving motor 250 that is the origin of the driving force is filtered. This is appropriately selected according to the noise generation source (generation position). For example, when noise is generated from the drive motor 250, the reference point of the drive side speed is the rotational axis of the drive motor 250, and when noise is generated from drive system elements such as gears and pulleys, The reference point of the drive side speed is set as the rotation axis of the specific drive system element (for example, the gear at the final stage), and the speed ratio between the drive system element and the drive roller 161 is used as the characteristic of the drive roller 161.

  Further, the characteristics of the belt in the filtering include the cycle of the conveyor belt 160, and the Fourier transformed profile data is effective so that the effective order is in a range of a constant multiple of the cycle of the conveyor belt. Delete frequencies of order or higher. The constant multiple here can also be an experimentally obtained numerical value “5”.

  Further, as a characteristic of the belt in the above filtering, a reduction ratio between the conveyance belt 160 and a driving roller 161 that drives the conveyance belt 160 may be used. In this case, for the Fourier-transformed profile data, frequencies higher than the effective order are deleted so that the effective order is up to a value obtained by dividing the reduction ratio by the noise frequency. The reduction ratio between the conveying belt 160 and the driving roller 161 can also be set to a numerical value “5” or more obtained experimentally.

  The profile data reduced in this way is sent from the data processing unit 402 to the data memory 403 through the data bus. The data memory 403 is a storage unit that stores belt profile data and roller profile data. The stored belt profile data and roller profile data are transmitted to the printing apparatus 100 via the communication interface 404 and the like.

  Processing operations when the belt profile data and the roller profile data are generated by the profile generation apparatus 400 having the above configuration will be described in detail. FIG. 5 is a block diagram schematically showing an operation procedure when generating a belt profile.

  First, the temporal variation of the speed ratio at each measurement point is calculated by the belt speed extraction unit 401b and the roller speed extraction unit 401a. Specifically, the belt speed extracting unit 401b and the roller speed extracting unit 401a measure the moving speed at two arbitrary measurement points on the belt by the transport speed measuring unit (S101 and S102). Specifically, the moving speed of the first measuring point is determined by measuring the change in the wavelength of incident light and reflected light with respect to the surface of the conveyor belt 160 that is an object by using a laser Doppler velocimeter 311. The speed of the measuring point is the rotational speed of the driven roller 162.

  The speed ratio calculation unit 401 calculates a speed ratio based on the moving speed optically measured by the laser Doppler speedometer 311 with respect to the rotation speed of the driven encoder 310 and the angular speed from the laser Doppler speedometer 311 ( S103), recording the temporal change of these speed ratios, makes the temporal variation of the moving speed a profile (S104 and S105).

  Here, the temporal fluctuation of the moving speed includes a speed fluctuation caused by thickness unevenness around the entire circumference of the transport belt and eccentricity of the support roller (for example, the driving roller 161). The belt speed extracting unit 401b extracts belt profile data having a frequency corresponding to the moving speed of the conveying belt from the temporal variation of the moving speed, and the roller speed extracting unit 401a is a time of the moving speed at each measurement point. From the mechanical variation, the temporal variation of the belt feed speed ratio caused by the eccentricity of the support roller is extracted as roller profile data.

  Next, in the data processing unit 402, the extracted belt profile and roller profile are subjected to Fourier transform, and the characteristics of the drive roller 161 (the period of the drive roller 161 and the drive roller are applied to the Fourier transformed data). In order to reduce the data size, filtering is performed so as to obtain an effective order corresponding to the speed ratio between the motor 161 and the drive motor 250, the frequency of a predetermined order or higher is deleted, and the inverse Fourier transform is performed (S106). ).

  The reduced profile data is sent from the data processing unit 402 to the data memory 403 through the data bus (S107). In this embodiment, the speed ratio data is recorded as data for one belt revolution.

  In this embodiment, the timing for acquiring the belt profile data and the roller profile data is the factory shipment. However, the acquisition timing is not limited to the time of shipment from the factory, and it can be triggered by a change in environment, a change with time, or a maintenance.

(Operation during profile generation)
The operation at the time of profile generation by the profile generation apparatus in the present embodiment having the above-described configuration will be described. FIG. 7 is a flowchart showing the procedure of the profile generation method in the present embodiment. FIG. 8 is a graph showing speed ratio data having a frequency corresponding to the speed fluctuation.

  First, the profile generator detects signals from the laser Doppler velocimeter 311 and the driven encoder 310. Then, the speed data for each palace of the encoder for one revolution of the belt is measured (S301).

  Next, the speed ratio calculation unit 401 uses the ratio of the moving speed and the rotational angular speed detected by the laser Doppler speedometer 311 and the driven encoder 310 to move the speed ratio data of the moving speed having a frequency corresponding to the speed fluctuation of the conveyor belt 160. Is extracted (S302). Here, as shown in FIG. 8A, the extracted speed ratio data includes thickness unevenness of the conveyor belt 160, eccentric information of the core material of the driven roller 162, and noise from the drive source. The minute vibration is reflected in the data.

  Next, the data processing unit 402 performs Fourier transform on the extracted speed ratio data, and performs frequency analysis (S303). FIG. 8B is a graph showing the frequency distribution of the speed ratio data subjected to Fourier transform. As can be seen from the figure, the effective data of the unevenness of the conveying belt includes zero order (not shown) representing the speed of the belt itself and primary to fifth order of thickness unevenness (effective data contributing to correction of thickness unevenness of the belt profile). Is the first to fifth), and the higher frequency component, the seventh order, has a low contribution to approximating belt thickness unevenness, and the frequency component higher than the eighth order, which is the cycle of the drive roller, is the eccentricity of the drive roller. Such noise is included.

  The effective data contributing to the correction of the eccentricity of the roller profile is the 8th to 40th order (the belt is one turn for the belt, the effective order is the 5th order as shown below), and the 48th order is the contribution to the correction. The 48th and higher order motors have a lot of driving noise. Considering the reduction ratio 1/8 of the belt to the roller, the frequency component of the motor for the roller is 8/8 to 40/8 = 1st to 5th order, and if the effective order is 5th order as with the belt, sufficient accuracy is assumed. I found out that In general, when a certain waveform is expanded by Fourier series, the first and fifth order sin and cos functions are acquired, and if the inverse Fourier transform is performed, the above-mentioned certain waveform can be substantially reproduced. It can be said that the effective order is good. In the present invention, the effective order after Fourier transform is set to a constant multiple of the roller period and the reduction ratio. As the constant multiple, when the driving roller 161 makes eight revolutions with respect to one revolution of the belt, 5 to 7 times is optimal together with the period and reduction ratio of the driving roller 161, and the contribution to the seventh-order accuracy is Since it was experimentally found to be small, the fifth order was adopted.

  Then, the belt speed extraction unit 401b and the roller speed extraction unit 401a perform filtering in the range of the effective order according to the characteristics of the driven roller 162 from the result of Fourier transform, delete a predetermined frequency, and perform roller profile Then, the belt profile is cut out (S304 and S306). Specifically, the 0th to 5th and 7th orders are effective orders in the belt profile, and the 8th to 40th orders are effective orders in the roller profile, and orders other than these effective orders are deleted.

  The belt speed extraction unit 401b extracts a range (P1) in which the effective order is 0th to 5th, which is the frequency of only the belt component shown in FIG. 8C (S304). Here, since the reduction ratio between the drive motor 250 and the driven roller 162 is 10: 1 and the noise period of the drive roller is ½, the reduction ratio is divided by the noise frequency from the result of Fourier transform. The range of the effective order is set to the 0th to the 5th order so that the range up to the calculated value is within the range of the effective order, and the frequency higher than the effective order is deleted. Then, inverse Fourier transform is performed on the filtered data (S305) to generate a belt profile. As shown in FIG. 8D, the data subjected to the inverse Fourier transform is reduced in data size by removing minute vibrations and rounding the data.

  On the other hand, the roller speed extraction unit 401a performs extraction in a range (P2) in which the effective order is 8 to 40th, which is the frequency of only the roller component shown in FIG. 8C (S306). Here, since the driven roller 162 makes eight revolutions per belt revolution, the roller profile is a constant multiple (5) of the roller period (eight revolutions), and the 8th to 8 × 5 = 40th orders are effective orders. Delete any more frequencies.

  Then, inverse Fourier transform is performed on each filtered data (S305 and S307), and a belt profile and a roller profile are generated. The calculated roller profile data and belt profile data are sent from the data processing unit 402 to the data memory 403 through the data bus and stored in the data memory 403. As described above, the roller profile data and the belt profile data are stored in the data memory 403 as independent profile data.

(Cumulative profile data)
Furthermore, in the present embodiment, cumulative data is calculated when calculating the speed ratio in step S302 described above. FIG. 9 is a flowchart showing a procedure for generating profile accumulated data.

  First, in the calculation of accumulated data, an arbitrary point such as HP is set as a reference point, and speed ratio data for each pulse of the encoder is acquired in order to obtain a speed ratio with respect to this reference point over the entire circumference of the conveyor belt 160 (S501). ), The values of the respective speed ratios are sequentially accumulated and calculated (S502).

  Specifically, the angular velocity at the rotation angle of the driven encoder 310 at an arbitrary time (t) is defined as ωt, and the velocity of the belt surface at the point measured by the LDV 311 at ωt is defined as Vt, and one of these two points is measured. The speed ratio at the other measuring point with respect to is the relative speed ratio Vt / ωt.

  Specifically, the speed of the belt surface at a point measured by the LDV 311 at a certain moment is set as a reference speed VA, and the moving speed of the conveyor belt 160 wound around the driven encoder 310 at that time is set as VB. Further, the belt moving speed VB at the point of the driven encoder 310 at an arbitrary time (t) is VB = ωt × Rt, where Rt is the rotation radius at that time. This change in Rt is a change in the thickness of the belt in the driven encoder 310 over time, and is obtained as VB / ωt = Rt. Here, if the expansion and contraction of the conveyor belt 160 is ignored, VA = VB, and the belt surface measured by the LDV 311 at an arbitrary time (t) is the speed Vt. Therefore, VA = VB = Vt and Vt / The relationship ωt = Rt is obtained. Therefore, by maintaining the thickness unevenness Rt at an arbitrary time as a profile, the VA at that moment can be corrected based on ωt, and landing deviation can be eliminated.

Then, as shown in the table below, the speed ratio at the reference point on the conveyor belt 160 (for example, the home position at t = 0) is set to the reference speed ratio V0 / ω0 = R0, and along the circumferential direction of the conveyor belt 160. The speed ratio Rt at each time is sequentially multiplied and accumulated, and the speed ratio Ct of each point with respect to the reference point is calculated over the entire circumference of the conveyor belt 160.

    After the speed ratio accumulated data is calculated in this way, the accumulated data is then subjected to various data processing such as zero correction. FIG. 10 is a graph showing the accumulated speed ratio. Here, in FIG. 10, the X axis represents the position of one round of the belt with an arbitrary correction reference point as the zero point, and the Y axis represents the speed ratio value with respect to the reference point. At the intersection (origin), the ratio value is 1. 10A is a plot of ratios (R0, R1, R2,... Rn) at the measurement points in Table 1, and FIG. 10B is an accumulation corresponding to each plot in FIG. Values (C0, C1, C2,... Cn) are plotted. In addition, FIG. 10C is corrected so that the entire plot of FIG. 10B becomes 0 or more.

  In the zero correction in step S503, first, as shown in FIG. 10A, the speed ratio at each point is set to a speed ratio 1 (= R0) on the basis of an arbitrary measurement point on the conveyor belt or its driving means. When the instantaneous speed ratios (R1, R2,... Rn) are sequentially multiplied and accumulated, as shown in FIG. 10B, data in which the speed ratios are accumulated is calculated.

  In the accumulated data calculated in this way, if there is negative data, all data is 0 as shown in FIG. The data is corrected so as to be as described above (S504). Data processing is performed in this way, and the accumulated data of the speed ratio is set as belt profile data (S505).

  The accumulated data of the speed ratio relating to the belt profile data calculated in this way is stored in the storage unit 332 of the printing apparatus 100 at the time of shipment, and is used as a belt profile at the time of printing.

  As described above, since the accumulated data is obtained by accumulating fluctuations in the speed ratio, the speed ratio with respect to the reference point can be obtained for the entire belt, and a series of behaviors associated with the circulation of the belt is shown in FIG. In addition, it is possible to handle it as an absolute change amount with the reference point as the origin, and the arithmetic processing can be simplified. That is, in order to eliminate the landing deviation, it is necessary to calculate an absolute positional deviation based on the appropriate landing position as indicated by Δd in FIG. 6, but momentarily at two measurement points on the belt. Since the measured value is a relative speed fluctuation between these two measurement points, an absolute speed fluctuation with respect to a predetermined reference point must be calculated when correcting the landing deviation. In the present embodiment, the speed ratio between two measurement points is accumulated, and Δd at each time point is stored as a profile in advance, so that it is possible to reduce the calculation processing burden at the time of printing execution.

  Furthermore, in this embodiment, the speed ratio with respect to the reference point can be obtained for each point on the belt by treating the accumulated speed ratio as accumulated data, and the instantaneous speed at each point on the belt can be obtained. It is possible to immediately grasp the deviation of the maximum amount accumulated in the entire belt, which cannot be predicted from data obtained by calculating the ratio in real time.

  More specifically, by making the belt profile data cumulative data, the speed ratio at each point on the belt as shown in FIG. 10C can be obtained as a sine curve with the reference point as the origin. By finding the maximum amplitude of the sine curve, it is possible to immediately grasp the maximum amount of deviation accumulated in the entire belt. As a result, for example, in the inspection at the time of factory shipment, it is possible to easily and quickly discriminate a product whose maximum deviation exceeds an allowable range.

(Action / Effect)
According to such a printing apparatus according to the present embodiment, during the printing process, the moving speed at any two arbitrary measurement points is measured, and the measurement result is determined based on the belt profile data and the roller profile data. By controlling the timing of image formation by the head, landing deviation can be reduced and image quality can be improved.

  In particular, in the present invention, the belt profile and the roller profile are subjected to Fourier transform with respect to the temporal variation of the speed ratio data and the belt feed speed ratio, and become effective orders corresponding to the characteristics of the transport belt 160 and the driving roller 161. As described above, the data is generated by deleting a predetermined frequency from the result of Fourier transform and further performing inverse Fourier transform, so that the data size of the profile can be reduced.

  Furthermore, in this embodiment, since the Fourier-transformed speed ratio data is filtered based on the cycle of the drive roller 161, the reduction ratio between the drive roller 161 and the drive motor 250, and the noise cycle, the profile accuracy is not impaired. The data size can be reduced by reducing noise from the drive source.

  Specifically, the profile data includes noise such as a driving source in addition to unevenness in the thickness of the conveyor belt 160 and eccentricity information of the core material of the driving roller 161 (FIG. 8A). The amount of data is huge. In this embodiment, as shown in FIG. 8D, data such as noise of the drive source is removed from the speed ratio data, so the data size is reduced.

  As a result, even for printing devices in which the belt moving speed fluctuates according to the resolution and printing mode, the profile data size is reduced, and the transport belt moving speed is simply calculated directly under each ink head. It is possible to avoid an increase in memory capacity and processing delay.

CR ... Normal route DR ... Discharge route FR ... Paper feed route R ... Registration part SR ... Reversal route 10 ... Recording medium 100 ... Printing device 110 ... Head unit 120 ... Side paper feed stand 130 ... Feed tray 140 ... Discharge Paper outlet 150 ... Discharge stand 160 ... Conveying belt 161 ... Drive roller 162 ... Driving roller 170,172 ... Switching mechanism 220 ... Side paper feed drive unit 230a, 230b ... Tray drive unit 240 ... Registration drive unit 250 ... Drive motor 260 ... First upper surface conveyance driving unit 265... Second upper surface conveyance driving unit 270... Upper surface discharge driving unit 281... Reverse driving unit 282 .. Refeeding driving unit 310 ... Driven side encoder 311 ... Laser Doppler velocimeter 312 ... Belt home position sensor 313 ... Roller home position sensor 330 ... Arithmetic processing unit 331 ... Supplement Control unit 331b ... Belt profile correction control unit 331a ... Roller profile correction control unit 332 ... Storage unit 332a, 332b ... Storage memory 333 ... Discharge control unit 334 ... Drive control unit 335 ... System control unit 340 ... Operation panel 400 ... Profile generation device 400a ... LDV device 400b ... PC
401 ... Speed ratio calculation unit 401a ... Roller speed extraction unit 401b ... Belt speed extraction unit 402 ... Data processing unit 403 ... Data memory 404 ... Communication interface

Claims (5)

An endless conveyor belt stretched between a plurality of support rollers;
Drive means for endlessly moving the conveyor belt;
In a printing apparatus having a plurality of ink heads that form a plurality of images so as to overlap each other on a recording sheet on the conveyance belt, an image control apparatus that controls image formation,
A belt profile storage unit that stores, as a belt profile, speed ratio data having a frequency corresponding to the speed ratio from temporal variation of the speed ratio between the support roller and an arbitrary measurement point on the conveyor belt;
A roller profile storage unit that stores, as a roller profile, a temporal variation in the belt feed speed ratio caused by the eccentricity of the support roller;
Print control means for controlling the timing of image formation by the ink head so that the positional deviation between the plurality of images on the conveyor belt is reduced based on the belt profile and the roller profile;
The belt profile and the roller profile are subjected to Fourier transform for temporal variation of the speed ratio data and the belt feed speed ratio, and Fourier transform is performed so as to have an effective order according to characteristics of the belt and the support roller. An image control device generated by deleting a predetermined frequency from the obtained result and further performing inverse Fourier transform. The characteristics of the support roller include the period of the support roller,
2. The image control apparatus according to claim 1, wherein a frequency equal to or higher than the effective order is deleted so that the Fourier transformed result has a range of an effective order that is a constant multiple of the roller period. . The characteristics of the support roller include a reduction ratio between the support roller and a drive shaft that drives the support roller,
2. The frequency of the effective order or higher is deleted so that the Fourier transform result has an effective order up to a value obtained by dividing the reduction ratio by a noise frequency. Image control device. The belt characteristics include the period of the belt, and the frequency of the effective order or higher is deleted so that the Fourier transformed result has a range of the effective order that is a constant multiple of the belt. The image control apparatus according to claim 1. The characteristics of the belt include a reduction ratio between the belt and a support roller that drives the belt,
2. The frequency of the effective order or higher is deleted so that the Fourier transform result has an effective order up to a value obtained by dividing the reduction ratio by a noise frequency. Image control device.