JP2013033080A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce wasteful standby time by performing an appropriate feeding control corresponding to time required for an adjustment of an image formation on a subsequent sheet when performing a successive image formation in an image forming apparatus, and thereby secure the productivity.SOLUTION: According to an image forming apparatus 100, when a successive image formation is performed in an image forming part 103, an engine control part 32 specifies, on the basis of a difference between a control value preliminarily set for an image formation on a preceding sheet and a control value preliminarily set for an image formation on a subsequent sheet, time required for an adjustment of the image formation on the subsequent sheet, and according to the specified required time, controls a timing of feeding the subsequent sheet.

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an electrophotographic image forming apparatus, various techniques have been proposed for improving productivity by shortening a printing time. For example, in Patent Document 1, the time from the start of polygon mirror rotation until it stabilizes to a predetermined target rotation speed is calculated by the calculation means based on the acceleration characteristics from the start of rotation of the polygon mirror until the speed is stabilized. By starting the rotation of the registration roller immediately after the specified time has elapsed, the majority of the rise time of the polygon mirror that has been consumed as a waiting time is used for the process time of transfer material transfer, etc., and the printing time is shortened. Techniques for achieving this are described.

JP-A-5-216306

  By the way, in an electrophotographic image forming apparatus, a process of fixing a toner image on a sheet by passing the sheet through a fixing unit on each side is performed. At this time, the paper shrinks due to heat during fixing. For this reason, when image formation is performed on both sides, it is necessary to finely adjust the image size (image magnification) of the front and back sides in order to increase the accuracy of the image positions on the front and back sides (front and back sides) of the paper.

One of the operations for finely adjusting the front and back image magnification is a method for finely adjusting the rotational speed of the polygon motor for rotating the polygon mirror. The image magnification adjustment operation using the polygon motor is designed to be completed within a predetermined sheet interval (normal sheet interval). The inter-paper interval is a period between the image formation on the preceding paper and the image formation on the succeeding paper, specifically, the succeeding paper is moved to the transfer position after the preceding paper is fed or re-fed to the transfer position. This is the time interval between feeding and refeeding.
However, the adjustment operation of the front and back image magnification using a polygon motor between the same paper and the operation of creating a patch toner image for correction of process conditions (referred to as a correction patch) on the intermediate transfer member may overlap. In this case, both cannot be operated in parallel. Therefore, by increasing the time between papers compared to between normal papers (delaying the paper feed timing or refeed timing) and sequentially performing the operation between them, productivity decreases, but between the same papers in both operations Implementation of.

  However, the adjustment operation of the front and back image magnification using a polygon motor has been conventionally performed despite the fact that the operation time varies depending on the setting values for each paper feed tray such as the front and back image magnification difference, registration correction amount, and linear velocity. The maximum value is controlled. For this reason, if the image magnification adjustment operation on the front and back and the correction patch formation overlap between the same paper, the paper space is widened even if both operations can be performed between normal papers depending on the magnification setting of the paper feed tray. There is a problem that an unnecessary productivity reduction occurs.

  The fixing control temperature is determined to be a target temperature suitable for the paper type and the amount of paper. When the target temperature of the fixing device changes due to the change of the paper feed tray during the operation, conventionally, the operation is performed such that the cycle is once reduced and restarted until the target temperature is reached. Alternatively, when the user gives priority to productivity, an operation of allowing continuous output without reaching the target temperature is performed. However, unnecessary waiting time may occur when the cycle is reduced uniformly. Further, even if there is a discrepancy between the target temperature and the actual temperature, if the output is uniformly performed, the output is performed in a state unfavorable for the user.

  An object of the present invention is to perform useless waiting time by performing appropriate sheet feeding control according to the time required for adjustment for image formation on a succeeding sheet when image forming is continuously performed in an image forming apparatus. Is to secure productivity.

In order to solve the above-mentioned problem, the invention described in claim 1
An image forming unit that forms an image on a sheet, and when performing image formation continuously in the image forming unit, between the sheets, which is a period between image formation on the preceding sheet and image formation on the following sheet, An image forming apparatus comprising: a control unit that causes the image forming unit to make an adjustment for image formation on the succeeding sheet based on a control value set in advance for image formation on the succeeding sheet. ,
The control unit is configured to perform the succeeding control based on a difference between a control value set in advance for image formation on the preceding paper and a control value set in advance for image formation on the succeeding paper. The time required for adjustment for image formation on the paper is specified, and the feeding timing of the succeeding paper is controlled based on the specified required time.

The invention according to claim 2 is the invention according to claim 1,
The control value is stored in the storage unit in association with the paper type or the paper feed tray.

The invention according to claim 3 is the invention according to claim 2,
The time required for the adjustment is stored in the storage unit in association with the difference between the control values.

The invention according to claim 4 is the invention according to claim 3,
For each of the paper feed trays, a front image adjustment magnification is set as a control value for image formation on the front surface of the paper loaded in the paper feed tray, and a back image adjustment is performed as a control value for image formation on the back surface. It has a setting part for setting the magnification,
The storage unit stores the image adjustment magnification of the front surface and the image adjustment magnification of the back surface for each paper feed tray set by the setting unit in association with each paper feed tray, and the difference between the front and back image adjustment magnifications. The time required for the image magnification adjustment of the image adjustment magnification difference is stored in association with each other,
The control unit stores the image in association with the paper feed tray on which the preceding paper is mounted when the image is formed on the other surface of the succeeding paper after the image is formed on the front or back surface of the preceding paper. The image adjustment magnification of the surface on which the preceding paper image is formed and the image adjustment magnification of the surface on which the image formation of the subsequent paper is stored in association with the paper feed tray on which the subsequent paper is mounted. Based on the difference, the time required for adjusting the image magnification for the succeeding sheet is specified, and the sheet feeding timing of the succeeding sheet is controlled based on the specified required time.

The invention according to claim 5 is the invention according to claim 4,
The image forming unit scans a laser beam based on the input image with a polygon mirror and exposes the photosensitive drum to form an electrostatic latent image on the photosensitive drum, and applies toner to the electrostatic latent image. An image is formed on the paper by developing it by attaching it and transferring it to the paper.
The controller adjusts the image magnification by adjusting a rotation speed of a polygon motor for rotating the polygon mirror.

The invention according to claim 6 is the invention according to claim 4 or 5,
The control unit includes means for causing the image forming unit to create a correction patch toner image for correcting a process condition at a predetermined timing, and the timing of the image magnification adjustment and the generation of the correction patch toner image is When the sheets overlap each other, the sheet feeding timing of the succeeding sheet is controlled based on the time required for adjusting the image magnification and the time required for creating the correction patch toner image.

The invention according to claim 7 is the invention according to claim 6,
The control unit determines whether or not a time obtained by adding the time required to adjust the image magnification and the time required to create the correction patch toner image exceeds a predetermined sheet interval, and determines that the time exceeds the predetermined time. Then, control is performed so as not to create a correction patch toner image, or a paper interval capable of both processes is calculated, and the feeding timing of the succeeding paper is controlled based on the calculated paper interval.

The invention according to claim 8 is the invention according to claim 7,
Whether or not the correction patch toner image is created and corrected when the time required for the image magnification adjustment and the correction patch toner image creation time exceeds a predetermined paper interval. This includes a paper gap correction execution enable / disable setting unit for the user to set whether or not.

The invention according to claim 9 is the invention according to claim 5,
A measuring unit configured to measure the time required for adjusting the image magnification between the image adjustment magnification on the front surface and the image adjustment magnification on the back surface set in each paper feed tray by rotating the polygon motor;

The invention according to claim 10 is the invention according to claim 3,
The storage unit stores a preset fixing target temperature for each sheet feeding tray as a control value in association with each sheet feeding tray, and also stores a fixing target temperature difference and a time required for adjusting the temperature difference. Memorize it,
The control unit includes a difference between a fixing target temperature stored in association with the paper feed tray loaded with the preceding paper and a fixing target temperature stored in correspondence with the paper feed tray loaded with the subsequent paper. The time required for adjusting the fixing target temperature for the succeeding paper is specified based on the above, and the feeding timing of the succeeding paper is controlled based on the specified required time.

  According to the present invention, when image formation is continuously performed in the image forming apparatus, it is possible to perform useless waiting time by performing appropriate paper feed control according to the time required for adjustment for image formation on the subsequent sheet. It is possible to reduce productivity and secure productivity.

1 is a diagram illustrating a schematic configuration example of an image forming apparatus. 2 is a block diagram illustrating a functional configuration of the image forming apparatus. FIG. It is a figure which shows an example of a tray setting screen. It is a figure which shows an example of an individual setting screen. It is a figure which shows an example of the polygon motor speed adjustment operation required time table. It is a flowchart which shows the paper gap determination process A performed by the engine control part of FIG. (A) is a figure which shows typically operation | movement of step S13-S14 of FIG. 5 when it is judged that the process of both the preparation of a correction patch and the rotation speed adjustment of a polygon motor is in time between normal paper, (B) is a case where it is determined that the processing of both the creation of the correction patch and the rotation speed adjustment of the polygon motor is not in time for the normal paper interval, and the user is permitted to widen the paper interval than the normal paper interval. It is a figure which shows typically operation | movement of step S13-S14 in the case of being. It is a flowchart which shows the polygon motor rotational speed adjustment time measurement process performed by the engine control part of FIG. It is a figure which shows an example of a fixing target temperature adjustment required time table. It is a flowchart which shows the paper gap determination process B performed by the engine control part of FIG. 2 in 2nd Embodiment. FIG. 10 is a diagram schematically illustrating sheet feeding timing when the user is allowed to widen the sheet interval from the normal sheet interval in the second embodiment.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. However, the scope of the invention is not limited to the illustrated examples.

[First Embodiment]
(Configuration of Image Forming Apparatus 100)
In the first embodiment, the sheet feeding timing is controlled based on the difference between the control value set for image formation on the preceding sheet and the control value set for image formation on the following sheet. As an example, a case will be described in which the paper feed timing is controlled based on a magnification difference between the front image adjustment magnification and the back image adjustment magnification set for a paper feed tray (paper) used for subsequent image formation.

  First, the configuration of the image forming apparatus 100 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the image forming apparatus 100 includes an image forming apparatus main body 101 and an image reading apparatus 102 on the upper part of the image forming apparatus main body 101. The image reading apparatus 102 includes an automatic document feeder 201 and a document image scanning exposure device 202.

  The document d placed on the document table of the automatic document feeder 201 is conveyed by a conveying unit, and one or both images of the document are scanned and exposed by the optical system of the document image scanning exposure device 202 to reflect the document image. Incident light is read into the line image sensor CCD.

  The analog image signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like, and becomes digital image data. This digital image data (digital image data) is input to the image writing units 3Y, 3M, 3C, 3K. Hereinafter, the symbols Y, M, C, and K in each part represent yellow, magenta, cyan, and black, respectively.

  The image forming apparatus main body 101 is a tandem color image forming apparatus in which a plurality of photosensitive drums 1Y, 1M, 1C, and 1K are arranged in tandem, and includes an image forming unit 103 and a paper feeding / conveying unit 104.

The image forming unit 103 fixes image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer member 6 as an image carrier, a secondary transfer roller 7A, an intermediate transfer member cleaning unit 8A, and a toner image. A fixing device 17.
The paper feeding / conveying unit 104 includes a paper feeding tray 20A, 20B, 20C, a feeding roller 21 and a paper feeding roller 22A provided in each of the paper feeding trays 20A, 20B, 20C, a conveying roller 22B, 22C, 22D, and a registration roller 23. , A paper discharge roller 24, a branching unit 26, a reverse gate 28, a reverse roller 29, and the like.

  Each of the photosensitive drums 1Y, 1M, 1C, and 1K is provided in the image forming units 10Y, 10M, 10C, and 10K in order.

  The image forming unit 10Y for forming a Y-color image is for the photosensitive drum 1Y on which a Y-color toner image is formed, and a Y-color for charging the surface of the photosensitive drum 1Y disposed around the photosensitive drum 1Y. A charging unit 2Y, an image writing unit 3Y that forms an electrostatic latent image by exposing an image pattern on the charging surface, and a developing device 4Y that develops the latent image surface with Y-color toner to form a toner image. And photosensitive drum cleaning means 8Y for removing the toner after the transfer of the toner image to the intermediate transfer body 6.

  Similarly, the image forming unit 10M for forming an M color image includes a photosensitive drum 1M on which an M color toner image is formed, an M color charging unit 2M disposed around the photosensitive drum 1M, and an image. It has a writing unit 3M, a developing device 4M, and a photosensitive drum cleaning means 8M.

  Similarly, an image forming unit 10C that forms a C color image includes a photosensitive drum 1C on which a C color toner image is formed, a C color charging unit 2C disposed around the photosensitive drum 1C, and an image. It has a writing unit 3C, a developing device 4C, and a photosensitive drum cleaning means 8C.

  Similarly, the image forming unit 10K that forms a K-color image includes a photosensitive drum 1K on which a K-color toner image is formed, a K-color charging unit 2K disposed around the photosensitive drum 1K, and image writing. It has a unit 3K, a developing device 4K, and a photosensitive drum cleaning means 8K.

  The charging unit 2Y and the image writing unit 3Y, the charging unit 2M and the image writing unit 3M, the charging unit 2C and the image writing unit 3C, and the charging unit 2K and the image writing unit 3K are respectively photoreceptor drums 1Y, 1M, An electrostatic latent image for each color is formed on 1C and 1K.

  Each of the image writing units 3Y, 3M, 3C, and 3K rotates a laser output unit that outputs laser light based on digital image data, a scanning mirror (polygon mirror) that scans the laser light in the main scanning direction, and a polygon mirror. With a polygon motor. Specifically, each of the image writing units 3Y, 3M, 3C, 3K scans the photosensitive drums 1Y, 1M, 1C, 1K by scanning laser light based on the digital image data with a polygon mirror. Thereby, latent images (electrostatic latent images) of images are formed on the photosensitive drums 1Y, 1M, 1C, and 1K.

  The developing devices 4Y, 4M, 4C, and 4K develop the electrostatic latent images by attaching charged toner to the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K on which the electrostatic latent images are formed. Development by the developing devices 4Y, 4M, 4C, and 4K is based on reversal development using a developing bias in which an AC voltage is superimposed on a DC voltage having the same polarity as the toner polarity to be used (in this embodiment, negative polarity). It is.

  An intermediate transfer member 6 as an image carrier is held so that an annular belt portion can rotate. The toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K by the developing devices 4Y, 4M, 4C, and 4K are transferred to the surface of the intermediate transfer body 6.

  Here, an outline of an image forming process performed by the image forming apparatus 100 will be described. Each color image formed by the image forming units 10Y, 10M, 10C, and 10K has a primary transfer roller 7Y to which a primary transfer bias having a polarity opposite to that of the toner to be used (in this embodiment, positive polarity) is applied. , 7M, 7C, 7K are sequentially transferred to the belt surface of the rotating intermediate transfer body 6 (primary transfer) to form a combined color image (color toner image). The color image is transferred from the intermediate transfer body 6 to the paper P at the transfer position.

  The paper P stored in the paper feed trays 20A, 20B, and 20C is fed by the feed roller 21 and the paper feed roller 22A provided in the paper feed trays 20A, 20B, and 20C, respectively, and the transport rollers 22B, 22C, and 22D, the registration roller 23, and the like are conveyed to the secondary transfer roller 7A, and a color image is transferred to one surface (front surface or back surface) of the paper P (secondary transfer).

  Then, the sheet P is heated by the fixing device 17 and the color image is fixed on the sheet P. As a result, a color image is formed on the paper P. The image-formed paper P is sandwiched between paper discharge rollers 24 and placed on a paper discharge tray 25 outside the apparatus. The transfer residual toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is cleaned by the photosensitive drum cleaning means 8Y, 8M, 8C, and 8K, and the process proceeds to the next image forming cycle.

At the time of double-sided image formation, the paper P formed on one side (front surface) and discharged from the fixing device 17 is branched from the sheet discharge path 26A by the branching unit 26, passes through the circulation sheet passing path 27A, and then reverses the gate. 28 leads to the reverse conveying path 27B. Then, after passing through the reverse roller 29, the paper P is conveyed in the reverse direction by the reverse rotation of the reverse roller 29. Then, the sheet P is conveyed to the refeed conveyance path 27C by switching the reversing gate 28 to the refeed conveyance path 27C, and merges at the conveyance roller 22D. Along with the switching of the reversing gate 28 to the refeed conveyance path 27C, the branching unit 26 is switched to the sheet discharge path 26A.
In the present embodiment, paper reversal paths (circulation paper passing path 27A, reversal conveyance path 27B, and refeed conveyance path 27C) that are out of the common path with single-sided image formation are collectively referred to as paper reversal. It is called a route.

  The reversely conveyed sheet P is conveyed again to the transfer position of the secondary transfer roller 7A through the registration roller 23 (that is, re-feeded), and the color image is transferred to the other side (back side). The sheet P on which the color image has been transferred is fixed by the fixing device 17, is nipped and conveyed by the sheet discharge roller 24, and is discharged to the sheet discharge tray 25 outside the apparatus. On the other hand, after the color image is transferred onto the paper P by the secondary transfer roller 7A, the residual toner is removed from the intermediate transfer body 6 from which the paper P has been separated by the intermediate transfer body cleaning means 8A.

  In the present embodiment, the paper reversing path is configured so that a plurality of sheets of paper can be built (held). When performing double-sided printing, first, the paper reversing path can be built in the paper reversing path in order to improve productivity. The image formation on the number of front surfaces is repeated, and then image formation on the front surface and the back surface that circulates back through the paper reversing path is performed alternately (alternate conveyance method).

Next, a control block diagram of the image forming apparatus 100 will be described with reference to FIG.
As shown in FIG. 2, the image forming apparatus 100 includes, as a control system, an overall control unit 31, an engine control unit 32, a reading control unit 33, an image reading device 102, an image forming unit 103, and a paper feed conveyance. Unit 104, operation display unit 105, and storage unit 106.

  The overall control unit 31 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. Specifically, the overall control unit 31 reads a program designated from the system program and various application programs stored in the ROM, expands the program in the RAM, and cooperates with the program expanded in the RAM. Various processes are executed to centrally control each unit of the image forming apparatus 100.

  For example, the overall control unit 31 receives image forming conditions (paper size, double side / single side, vertical / horizontal, density, etc.) from the operation display unit 105 and the image data of the original is input by the image reading device 102. (Job information is input), the job is executed based on the input job information, and the engine control unit 32 controls image formation.

The engine control unit 32 includes a CPU, a ROM, a RAM, and the like, and executes various processes in cooperation with the CPU and a program stored in the ROM, and controls the image forming unit 103 and the paper feeding / conveying unit 104. Specifically, the engine control unit 32 executes a paper gap determination process A, which will be described later, based on an instruction from the overall control unit 31, and determines whether to perform front / back magnification adjustment and correction patch creation between the papers in the image forming unit 103. In addition, the paper interval is determined based on the results of the execution determination, and the image forming unit 103 and the paper feeding / conveying unit 104 are controlled to adjust the front / back image magnification, the correction patch, and the paper feeding according to the determined paper interval. Control the timing.
Here, the front and back image magnification adjustment is to finely adjust the image size deviation between the front and back images caused by the shrinkage of the paper due to heat at the time of fixing, thereby matching the front and back image sizes. The front and back image magnification is adjusted by finely adjusting the rotation speed of the polygon motor for rotating the polygon mirror. When the rotation speed of the polygon motor is adjusted, the rotation speed of the polygon mirror is adjusted, and the exposure speed to the photosensitive drums 1Y, 1M, 1C, and 1K is adjusted. Thus, the front and back image magnification is adjusted.
The correction patch is a patch used to correct the process conditions of the image forming unit 103 in order to obtain a stable image. This correction patch is drawn on the intermediate transfer body 6 and is used for correction for adjusting the surface potentials of the photosensitive drums 1Y, 1M, 1C, and 1K, density correction, gradation correction, and the like.

  The reading control unit 33 controls the operation of the image reading apparatus 102 in accordance with an instruction from the overall control unit 31.

  The operation display unit 105 is configured by an LCD (Liquid Crystal Display) or the like, and displays various operation buttons, device status display, operation status of each function, etc. on the display screen according to instructions of a display signal input from the overall control unit 31. Display. The LCD display screen is covered with a pressure-sensitive (resistive film pressure) touch panel configured with transparent electrodes arranged in a grid, and the XY coordinates of the force point pressed with a finger or a touch pen are expressed as voltage values. The detected position signal is output to the overall control unit 31 as an operation signal. The operation display unit 105 includes various operation buttons such as a numeric button and a start button, and outputs an operation signal generated by the button operation to the overall control unit 31.

In the present embodiment, the operation display unit 105 functions as a paper gap correction execution enable / disable setting unit 105a and a tray setting unit 105b.
The paper gap correction execution enable / disable setting unit 105a widens the paper gap when both the creation of the correction patch and the front and back image magnification adjustment are not completed. A paper gap correction execution setting screen is displayed for the user to set whether or not to create.
The tray setting unit 105b displays a tray setting screen 150 for the user to set setting information regarding each paper feed tray.

FIG. 3 a shows an example of the tray setting screen 150. As shown in FIG. 3a, on the tray setting screen 150, a tray selection field 150a in which buttons for identification numbers (tray 1, tray 2,. And a setting display field 150b for displaying setting information about the tray corresponding to the. Setting items that can be set from the tray setting screen 150 (including the individual setting screen 151 in FIG. 3B) include information (paper size, paper type, basis weight, etc.) indicating the type of paper loaded in the paper feed tray, Examples include control values (image adjustment magnification, target temperature of the fixing roller, etc.) when image formation is performed on the paper. When the button of the tray to be set is pressed from the tray selection field 150a and the “change setting” button 150c is pressed, an individual setting screen 151 shown in FIG. 3B is displayed.
As shown in FIG. 3B, the individual setting screen 151 includes a setting item selection field 151a for selecting a setting item, and a setting value input field 151b for inputting a setting value for the selected setting item. Is provided. When a setting value is input from the setting value input field 151b and the OK button 151c is pressed, the input setting value is associated with the setting item and stored in the storage unit 106 as tray setting information 106b.

  In order to adjust the front / back image magnification, it is necessary to set the image adjustment magnification of the front surface and the image adjustment magnification of the back surface in accordance with the expansion / contraction ratio of the paper. For this purpose, “front / back adjustment” is selected from the setting item selection field 151a, and the magnification values (for example, −100 to + 100step, 0.01% / It can be set by inputting (step value). In this way, by making it possible to finely adjust the image magnification of the front and back sides of the paper, it becomes possible to meet the high image quality required in the product print field.

The storage unit 106 is configured by a nonvolatile memory, an HDD, or the like, and is used when executing various processing programs in the image forming apparatus 100, and data of processing results calculated by the overall control unit 31 and the engine control unit 32. The image data instructed to be stored is stored.
In the present embodiment, the storage unit 106 sets the paper gap correction execution setting information 106a, which is a setting value input from the paper gap correction execution setting unit 105a, and the settings corresponding to the setting items input from the tray setting unit 105b. The tray setting information 106b, which is a value, and the polygon motor speed adjustment operation required time table 106c are stored.

FIG. 4 shows an example of the polygon motor speed adjustment operation required time table 106c. As shown in FIG. 4, the polygon motor speed adjustment operation required time table 106c associates the image magnification difference between the front and back and the operation required time for adjusting the rotation speed of the polygon motor according to the image magnification adjustment of the image magnification difference. It is a table to memorize.
Here, the polygon motor is driven at a rotational speed corresponding to the image adjustment magnification of the front surface set from the tray setting unit 105b when forming an image on the front surface of the paper, and is formed when forming an image on the back surface of the paper. It is driven at a rotation speed corresponding to the image adjustment magnification of the back image. Therefore, when the image of the back side is formed next to the front side, or when the image of the front side is formed next to the back side, if the image adjustment magnifications set on the front and back sides are different, the rotation speed of the polygon motor is set. It is necessary to finely adjust (switch) the sheet according to the image adjustment magnification of the next side between sheets. This adjustment time varies depending on the magnification difference between the front and back sides. Therefore, the polygon motor speed adjustment operation required time for each magnification difference between the front and back is stored in the polygon motor speed adjustment operation required time table 106c.
In FIG. 4, for simplicity, the time required for the adjustment operation from the surface magnification to the back surface magnification and the time required for the adjustment operation from the back surface magnification to the surface magnification are shown as common, but depending on the characteristics of the polygon motor It can be considered that the time required for the adjustment operation from the magnification to the rear surface magnification is different from the time required for the adjustment operation from the rear surface magnification to the front surface magnification. In such a case, it is preferable to store both the time required for the adjustment operation from the front surface magnification → the back surface magnification and the back surface magnification → the front surface magnification for each of the front and back magnification differences.

(Operation of Image Forming Apparatus 100)
Next, the operation of the image forming apparatus 100 will be described.
A paper interval determination process A, which is a flowchart of the paper interval determination process A executed by the engine control unit 32 in FIG. 5, is executed when a job start is notified from the overall control unit 31.

Here, when image formation on both sides is performed continuously by the alternate conveyance method, the image adjustment magnification of the front and back sides is changed when switching between image formation on the front surface (back surface) of the preceding paper and image formation on the back surface (front surface) of the subsequent paper. Unless it is the same, fine adjustment (switching) of the rotational speed of the polygon motor is required between sheets as described above. If the front and back image adjustment magnifications are the same, it is only necessary to maintain the rotational speed of the polygon motor from the image formation of the preceding paper, so adjustment between papers is unnecessary. The timing required to adjust the rotational speed of the polygon motor and to create a correction patch may overlap between the same sheets. In this case, if the correction patch is created at the same time while adjusting the rotation speed of the polygon motor between the paper, the correction patch will be lost and accurate drawing will not be possible, and feedback to the process conditions based on the correction patch will also be appropriate It becomes impossible to do. Therefore, conventionally, both processes are made compatible by adjusting the rotational speed of the polygon motor after the correction patch is created. At this time, both processes are realized by extending the sheet interval to the time added to the correction patch creation time, considering the rotation speed adjustment time of the polygon motor as a fixed maximum value. However, the time required for adjusting the rotation speed of the polygon motor differs depending on the difference between the front and back image adjustment magnifications set for the tray used for paper feed. May go down. In addition, in the case of a user who emphasizes productivity, there is a case where it is not desired to widen the paper gap.
Therefore, in the image forming apparatus 100, the engine control unit 32 performs the paper gap determination process A shown in FIG. 5 at the start of image writing on the preceding paper in the job, and corrects the paper gap between the preceding paper and the succeeding paper. Based on the necessity of patch generation, polygon motor rotation speed adjustment, etc., determination of processing to be performed between sheets and control of sheet feeding timing in consideration thereof are executed.

  In the paper gap determination process A, it is first determined whether or not it is necessary to create a correction patch between the paper and the subsequent paper (step S1). Here, the creation of the correction patch is performed, for example, at a predetermined print number interval.

When it is determined that it is not necessary to create a correction patch between sheets (step S1; NO), it is determined whether or not the rotation speed of the polygon motor needs to be adjusted (step S2).
In step S2, first, from the tray setting information 106b stored in the storage unit 106, the image adjustment magnification associated with the paper feed tray used to feed the preceding paper (if the front paper is front side printing, The image adjustment magnification, or the back side image adjustment magnification for back side printing) is read out. Next, from the tray setting information 106b stored in the storage unit 106, the image adjustment associated with the paper feed tray used for feeding the subsequent paper (used when paper is printed on the back side when the subsequent paper is backside printing). The magnification (the image adjustment magnification of the front side if the succeeding sheet is front side printing, and the image adjustment magnification of the back side if the subsequent paper is printed) is read. Then, the difference between the two read image adjustment magnifications is calculated, and if the difference in magnification is not 0, it is determined that the rotation speed of the polygon motor needs to be adjusted. If the magnification difference is 0, it is determined that the polygon motor rotation speed adjustment is unnecessary. The calculated magnification difference is stored in the RAM for use in step S6.

If it is determined in step S2 that the polygon motor rotation speed adjustment is necessary (step S2; YES), the time required for the polygon motor rotation speed adjustment is equal to or less than the normal sheet interval. ) Is determined as the normal paper feed timing (step S3). Then, between the sheets, the rotation speed of the polygon motor is adjusted based on the image adjustment magnification of the surface on which the image of the subsequent sheet is formed (step S4), and the normal sheet feeding timing (that is, between the preceding sheet and the sheet) is adjusted. Feeding (re-feeding in the case of the back side) is performed by the sheet feeding / conveying unit 104 at a timing when there is a normal sheet interval (step S18).
If it is determined in step S2 that it is not necessary to adjust the rotation speed of the polygon motor (step S2; NO), there is no time required to create and adjust the correction patch between the sheets, so the next paper feed timing is set to the normal feed timing. The paper timing is determined (step S17). Then, paper feeding (re-feeding in the case of the back side) is performed by the paper feeding / conveying unit 104 at the normal paper feeding timing (step S18).

On the other hand, if it is determined in step S1 that a correction patch needs to be created between sheets (step S1; YES), it is determined whether or not the rotation speed of the polygon motor needs to be adjusted (step S5). . The determination method in step S5 is the same as that described in step S2.
If it is determined that it is not necessary to adjust the rotation speed of the polygon motor (step S5; NO), the time required to create the correction patch is less than or equal to the normal sheet interval, so the next sheet supply timing is determined as the normal sheet supply timing. (Step S6). Then, a correction patch is created between the sheets (step S7), and sheet feeding (re-feeding in the case of the back side) is performed by the sheet feeding / conveying unit 104 at the normal sheet feeding timing (step S18).

  On the other hand, if it is determined in step S5 that the rotation speed adjustment of the polygon motor is necessary (step S5; YES), the polygon motor speed adjustment operation time table 106c stored in the storage unit 106 is referred to, and the preceding The time required for the polygon motor rotation speed adjustment operation corresponding to the adjustment magnification difference between the paper image and the subsequent paper image is acquired (step S8). Here, the magnification difference stored in the RAM in the determination process of step S2 is used as the adjustment magnification difference between the images of the preceding paper and the succeeding paper.

  Next, based on the acquired time required for the polygon motor rotation speed adjustment operation, it is determined whether or not the processing of both the correction patch creation and the polygon motor rotation speed adjustment is in time between normal sheets (step S9). . When the sum of the required correction patch creation time (fixed) and the acquired operation required time is equal to or less than the normal paper interval, it is determined that the normal paper is in time. If the total of the required correction patch creation time (fixed) and the acquired operation required time exceeds the interval between the normal sheets, it is determined that the interval between the normal sheets is not enough.

  If it is determined in step S9 that both the correction patch creation and the polygon motor rotation speed adjustment process are in time (step S9; YES), the next paper feed timing is determined as the normal paper feed timing. (Step S10). Then, a correction patch creation process (step S13) and then a polygon motor rotation speed adjustment operation are sequentially performed (step S14). Paper feeding) is performed (step S18).

  FIG. 6A is a diagram schematically showing the operations in steps S13 to S14 when it is determined that both processing for creating a correction patch and adjusting the rotational speed of the polygon motor are in time between normal sheets. As shown in FIG. 6A, a correction patch is first created (required time t1) at a normal paper interval t0 from the image formation of the preceding paper P1 to the image formation of the subsequent paper P2, and then the polygon motor Rotational speed adjustment (required time t2) is performed.

  If it is determined that the correction patch creation and the polygon motor rotation speed adjustment processing are not in time between normal sheets (step S9; NO), the inter-sheet correction correction availability setting information 106a stored in the storage unit 106 is determined. Based on the above, it is determined whether or not the interval between the sheets may be wider than the interval between the normal sheets (step S11). If it is determined that the gap between the sheets may be larger than that between the normal gaps (step S11; YES), the necessary intervals between the correction patches and the rotation speed of the polygon motor are added up to obtain the necessary gap between the sheets. The next paper feed timing is determined according to the calculated paper interval (step S12). Then, correction patch creation processing (step S13), and then the rotational speed adjustment of the polygon motor are sequentially performed (step S14), and the determined paper feed timing (ie, the paper feed interval to the transfer position with the preceding paper) is corrected. Paper feeding is performed by the paper feeding / conveying unit 104 at a timing when the time required for the patch creation and the polygon motor rotation speed adjustment is added (step S18).

  FIG. 6B shows a case where it is determined that the processing of both the creation of the correction patch and the adjustment of the rotation speed of the polygon motor is not in time for the normal paper space. It is a figure which shows typically operation | movement of step S13-S14 in the case of being accepted. As shown in FIG. 6B, the correction patch is first created (required time t1), and then the polygon motor rotation speed adjustment (required time t3) is performed. Since t1 + t3 = t4 is longer than the normal paper gap t0, the paper gap is widened at t4.

  If it is determined in step S11 that the interval between sheets is not allowed to be larger than that between normal sheets (step S11; NO), the next sheet feeding timing is determined as the normal sheet feeding timing (step S15). Then, the creation of the correction patch is omitted, and only the rotation speed adjustment of the polygon motor is performed (step S16), and the paper feeding / conveying unit 104 feeds paper (re-feeding in the case of the back side) at the determined paper feeding timing. Performed (step S18). When the correction patch is not created, the correction patch may be created at a timing such as idling, warm-up, or completion of printing. Further, the user may be able to set from the operation display unit 105 at which timing the correction patch is created.

  In the above embodiment, it has been described that the difference in image adjustment magnification between the front surface and the back surface and the rotation speed adjustment time of the polygon motor are stored in advance in the polygon motor speed adjustment operation required time table 106c. It is also possible to measure the polygon motor rotation speed adjustment time in accordance with the difference between the image adjustment magnifications on the front surface and the back surface, and store the measurement result in a table (see FIG. 7). In addition, at the start of printing, the rotation speed adjustment time of the polygon motor may be measured according to the difference in image adjustment magnification between the front and back surfaces of the paper feed tray to be used. As described above, when the measurement is performed at the idle time or at the start of printing, individual differences of the polygon motor and changes in characteristics over time can be taken into consideration.

FIG. 7 shows a flowchart of a polygon motor rotation speed adjustment time measurement process executed by the engine control unit 32.
First, the measurement target tray is selected, and the image adjustment magnification of the front surface and the rear image adjustment magnification of the measurement target tray are acquired from the tray setting information 106b (step S21).

  Next, the magnification difference between the front surface and the back surface is calculated, and it is determined whether or not the magnification difference has already been measured (step S22). If it is determined that the magnification difference has not already been measured (step S22; NO), the polygon motor is driven at a rotational speed corresponding to the image adjustment magnification on the paper surface (step S23), and the polygon motor is adjusted to the image adjustment magnification on the surface. It waits until it operates stably at the corresponding speed (step S24). When the polygon motor stably operates at a rotation speed corresponding to the image adjustment magnification of the surface (step S24; YES), the current time (A) is stored in the RAM (step S25).

  Next, the rotation speed of the polygon motor is switched to a speed corresponding to the image adjustment magnification on the back side (step S26), and the system waits until the polygon motor operates stably at a speed corresponding to the image adjustment magnification on the back side (step S27). ). When the polygon motor stably operates at the rotation speed corresponding to the back surface (step S27; YES), the current time (B) is stored in the RAM (step S28).

  Next, the time required for adjusting the rotation speed of the polygon motor (polygon motor rotation speed adjustment time: B−A) is calculated (step S29). The calculated polygon motor rotation speed adjustment time is stored in the data buffer of the measurement target tray of the data buffer for each paper feed tray (step S30), and the process proceeds to step S32.

  On the other hand, if it is determined in step S22 that the magnification difference has already been measured (step S22; YES), the measured polygon motor rotation speed adjustment time data of the same magnification difference is stored in the data buffer corresponding to the measurement target tray. Stored (step S31), the process proceeds to step S32.

  In step S32, it is determined whether or not the measurement for all trays has been completed. If it is determined that the measurement has not been completed for all trays (step S32; NO), the process returns to step S21. If it is determined that the measurement for all trays has been completed (step S32), the polygon motor rotation speed adjustment time measurement process ends.

In the polygon motor rotation speed adjustment time measurement process, the measurement result is stored in the data buffer for each tray. However, as shown in the polygon motor speed adjustment operation time table 106c shown in FIG. 106 may be stored. Further, the time required for the rotation speed adjustment operation of the polygon motor may be stored as a part of the tray setting information 106b.
In the polygon motor rotation speed adjustment time measurement process, the case where the time required for the adjustment operation from the front surface magnification to the rear surface magnification is measured is described as an example. Since the time required for the adjustment operation and the time required for the adjustment operation from the back magnification to the surface magnification may be different, the time required for the adjustment operation from the back magnification to the surface magnification may be measured and stored together. preferable.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
In the first embodiment, as an example of controlling the paper feed timing based on the difference between the control value used for image formation on the preceding paper and the control value used for image formation on the subsequent paper, the paper feed tray used ( The case where the sheet feeding timing is controlled based on the magnification difference between the image adjustment magnification on the front surface and the image adjustment magnification on the back surface set in (paper) has been described. In the second embodiment, the sheet is fed based on the difference between the fixing target temperature set for the preceding paper feed tray (paper) and the fixing target temperature set for the subsequent paper feeding tray (paper). A case where the paper timing is controlled will be described.

  In the second embodiment, the operation display unit 105 sets whether or not to extend the paper interval for the user to set whether or not the paper interval may be wider than the normal paper interval in order to adjust the fixing target temperature. Part (not shown). In the second embodiment, the storage unit 106 stores the fixing target temperature switching required time table 106d and the inter-paper extension enable / disable setting information (not shown) in addition to the tray setting information 106b.

FIG. 8 shows an example of the fixing target temperature adjustment required time table 106d. As shown in FIG. 8, the fixing target temperature adjustment required time table 106 d is a table that stores the fixing target temperature difference and the time required for adjusting the fixing target temperature by the fixing target temperature difference in association with each other.
In FIG. 8, the temperature adjustment time required from the low temperature side to the high temperature side and the temperature adjustment time required from the high temperature side to the low temperature side are shown as common in FIG. If the time required for temperature adjustment differs from the time required for temperature adjustment from the high temperature side to the low temperature side, the time required for temperature adjustment from the low temperature side to the high temperature side and the temperature adjustment time required from the high temperature side to the low temperature side for each fixing target temperature difference. It is preferable to store both the time required for temperature adjustment in association with each other.

  Since the other configuration is the same as that described in the first embodiment, the operation of the second embodiment will be described with the aid of the description.

FIG. 9 shows a flowchart of the paper gap determination process B executed by the engine control unit 32 in the second embodiment.
First, it is determined whether or not a fixing target temperature adjustment operation is necessary (step S31). In step S31, first, the fixing target temperature associated with the paper feed tray used for feeding the preceding paper is read from the tray setting information 106b stored in the storage unit 106. Next, from the tray setting information 106b stored in the storage unit 106, the fixing target temperature associated with the paper feed tray used for feeding the succeeding paper (used for paper feeding in the case of the back side) is read out. . Then, the difference between the two read fixing target temperatures is calculated, and if the temperature difference is not 0, it is determined that the fixing target temperature needs to be adjusted. If the magnification difference is 0, it is determined that the operation for adjusting the fixing target temperature is unnecessary.
Here, as shown in FIG. 3a, the tray setting unit 105b is provided with a plurality of setting items (fixing roller center temperature, fixing roller end temperature, fixing lower belt center temperature, etc.) regarding the fixing target temperature. In such a case, for each of the items, a fixing target temperature difference set in the paper feed tray for the preceding paper and the succeeding paper is obtained, and the maximum value is set as the fixing target temperature used for paper feed control.
The calculated temperature difference of each item is stored in the RAM for use in step S33.

  When it is determined that the fixing target temperature adjustment is necessary (step S31; YES), the paper interval may be expanded from the normal paper interval based on the paper interval extension enable / disable setting information stored in the storage unit 106. Is determined (step S32).

  If it is determined that the interval between the sheets may be larger than the interval between the normal sheets (step S32; YES), the maximum temperature difference among the fixing target temperature differences for each item and the fixing target temperature adjustment required time table 106d are displayed. Based on this, the paper feed timing is determined (step S33). Specifically, the fixing target temperature adjustment required time t11 corresponding to the maximum fixing target temperature difference among the fixing target temperature differences between the preceding paper and the succeeding paper is acquired from the fixing target temperature adjustment required time table 106d, and is shown in FIG. As shown, the acquired required time t11 is specified as the time required for adjustment, and the timing at which the period from the image formation of the preceding paper to the image formation of the subsequent paper becomes t11 is determined as the paper feed timing. Then, a fixing target temperature adjustment operation is performed (step S34), and the paper is fed by the paper feeding / conveying unit 104 at the determined paper feeding timing (that is, the timing at which it is separated from the preceding paper by the acquired required time t11). Paper (re-feeding in the case of the back side) is performed (step S36).

  On the other hand, when it is not permitted to widen the gap between the sheets more than the gap between the normal sheets (step S32; NO), the next paper feed timing is determined as the normal paper feed timing (step S35), and at the determined paper feed timing. Paper feed (re-feed in the case of the back side) is performed by the paper feed conveyance unit 104 (step S36).

  As described above, according to the image forming apparatus 100, when the image forming unit 103 performs image formation continuously, the engine control unit 32 performs control that is set in advance for image formation on the preceding sheet. Based on the difference between the value and the control value set in advance for image formation on the succeeding paper, the time required for adjustment for image formation on the succeeding paper is specified, and the specified required time is Based on this, the timing for feeding the subsequent sheet is controlled.

  Accordingly, the image forming unit 103 performs sheet feeding at an appropriate sheet feeding timing according to the time required to adjust (switch) the operation according to the control value of the preceding sheet from the operation according to the control value of the preceding sheet. As a result, wasteful waiting time can be reduced and productivity can be secured.

  By adopting a configuration in which the control value is stored in the storage unit 106 in association with the type of paper or the paper feed tray, it is possible to easily control the appropriate paper feed timing according to the paper to be the subsequent paper. It becomes.

  In addition, the time required for adjustment is easily stored in the storage unit 106 in advance in association with the difference between the control values, so that the time required for the adjustment can be easily specified.

Further, for example, the image adjustment magnification of the surface on which the image formation of the preceding paper stored in association with the paper feed tray loaded with the preceding paper and the paper feeding tray loaded with the subsequent paper are stored in association with each other. The time required for image magnification adjustment for the subsequent paper is specified based on the difference from the image adjustment magnification of the image forming surface of the subsequent paper, and the paper feeding timing of the subsequent paper is determined based on the specified required time. By controlling, useless waiting time can be reduced and productivity can be secured.
Specifically, the image adjustment magnification of the surface on which the image formation of the preceding paper stored in association with the paper feed tray loaded with the preceding paper and the paper feeding tray loaded with the subsequent paper are stored in association with each other. The time required for adjusting the rotation speed to the polygon motor according to the image adjustment magnification for the succeeding paper is determined based on the difference from the image adjustment magnification of the image forming surface of the succeeding paper, and the specified required time Based on the above, by controlling the sheet feeding timing of the succeeding sheet, it is possible to reduce useless waiting time and secure productivity.

  In addition, the image forming unit 103 has means for forming a correction patch toner image for correcting the process condition at a predetermined timing, and the timing of image magnification adjustment and the formation of the correction patch toner image overlap between the same sheets. In this case, by controlling the sheet feeding timing of the succeeding sheet based on the time required for adjusting the image magnification and the time required for forming the correction patch toner image, a wasteful waiting time during which no processing is performed can be achieved. It is possible to reduce and secure productivity.

Further, it is determined whether or not the time required for adjusting the image magnification and the time required for generating the correction patch toner image exceeds a predetermined sheet interval. Is controlled so as not to be created, or the paper interval that can be processed by both is calculated, and the feeding timing of the succeeding paper is controlled based on the calculated paper interval, thereby placing importance on productivity. Paper feed control or paper feed control with an emphasis on image quality can be performed.
Also, whether or not correction patch toner images are created and corrected when the total time required for image magnification adjustment and the time required to create correction patch toner images exceeds a predetermined sheet interval. By including a paper gap correction execution enable / disable setting unit for the user to set the paper feed, appropriate paper feed control according to whether the user attaches importance to productivity or image quality becomes possible.

  Further, by providing a measurement unit that measures the time required for image magnification adjustment between the image adjustment magnification of the front surface and the image adjustment magnification of the back surface set for each paper feed tray by rotating a polygon motor, It is possible to specify the time required for image magnification adjustment in consideration of individual differences of polygon motors and changes with time.

  For example, based on the difference between the fixing target temperature stored in association with the paper feed tray loaded with the preceding paper and the fixing target temperature stored in correspondence with the paper feed tray loaded with the subsequent paper. By specifying the required time for adjusting the fixing target temperature for the succeeding paper and controlling the feeding timing of the succeeding paper based on the specified required time, the cycle is once reduced until the target temperature is uniformly reached. It is possible to reduce unnecessary waiting time and secure productivity.

  Note that the description in the above embodiment shows a preferred example of the image forming apparatus according to the present invention, and the present invention is not limited to this.

  For example, in the above embodiment, the present invention has been described by taking the image magnification adjustment and the fixing target temperature adjustment as examples. However, the present invention is not limited to this.

  In the above description, an example in which a ROM, a nonvolatile memory, a hard disk, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of the image forming apparatus 100 can be changed as appropriate without departing from the spirit of the present invention.

1Y, 1M, 1C, 1K Photosensitive drums 2Y, 2M, 2C, 2K Charging means 3Y, 3M, 3C, 3K Image writing unit 4Y, 4M, 4C, 4K Developing device 6 Intermediate transfer body 7Y, 7M, 7C, 7K 1 Next transfer roller 8A Intermediate transfer member cleaning means 8Y, 8M, 8C, 8K Photosensitive drum cleaning means 10Y, 10M, 10C, 10K Image forming unit 17 Fixing device 20A, 20B, 20C Paper feed tray 21 Feed roller 22A Paper feed Roller 22B, 22C, 22D Conveying roller 23 Registration roller 24 Discharging roller 25 Discharging tray 26 Branching means 27A Circulating paper path 27B Reverse conveying path 27C Refeed conveying path 31 Overall control unit 32 Engine control unit 33 Reading control unit 102 Image reading device 103 Image forming unit 104 Paper feeding and conveying unit 105 Work display section 105a Paper gap correction execution availability setting section 105b Tray setting section 150 Tray setting screen 151 Individual setting screen 106 Storage section 106a Paper gap correction execution availability setting information 106b Tray setting information 106c Polygon motor speed adjustment operation required time table

Claims (10)

An image forming unit that forms an image on a sheet, and when performing image formation continuously in the image forming unit, between the sheets, which is a period between image formation on the preceding sheet and image formation on the following sheet, An image forming apparatus comprising: a control unit that causes the image forming unit to make an adjustment for image formation on the succeeding sheet based on a control value set in advance for image formation on the succeeding sheet. ,
The control unit is configured to perform the succeeding control based on a difference between a control value set in advance for image formation on the preceding paper and a control value set in advance for image formation on the succeeding paper. An image forming apparatus that specifies a time required for adjustment for image formation on paper and controls the timing of feeding the succeeding paper based on the specified time required.   The image forming apparatus according to claim 1, wherein the control value is stored in a storage unit in association with a paper type or a paper feed tray.   The image forming apparatus according to claim 2, wherein the time required for the adjustment is stored in the storage unit in association with the difference between the control values. For each of the paper feed trays, a front image adjustment magnification is set as a control value for image formation on the front surface of the paper loaded in the paper feed tray, and a back image adjustment is performed as a control value for image formation on the back surface. It has a setting part for setting the magnification,
The storage unit stores the image adjustment magnification of the front surface and the image adjustment magnification of the back surface for each paper feed tray set by the setting unit in association with each paper feed tray, and the difference between the front and back image adjustment magnifications. The time required for the image magnification adjustment of the image adjustment magnification difference is stored in association with each other,
The control unit stores the image in association with the paper feed tray on which the preceding paper is mounted when the image is formed on the other surface of the succeeding paper after the image is formed on the front or back surface of the preceding paper. The image adjustment magnification of the surface on which the preceding paper image is formed and the image adjustment magnification of the surface on which the image formation of the subsequent paper is stored in association with the paper feed tray on which the subsequent paper is mounted. The image forming apparatus according to claim 3, wherein a time required for image magnification adjustment for the succeeding sheet is specified based on the difference, and a sheet feeding timing of the succeeding sheet is controlled based on the specified required time. The image forming unit scans a laser beam based on the input image with a polygon mirror and exposes the photosensitive drum to form an electrostatic latent image on the photosensitive drum, and applies toner to the electrostatic latent image. An image is formed on the paper by developing it by attaching it and transferring it to the paper.
The image forming apparatus according to claim 4, wherein the control unit adjusts the image magnification by adjusting a rotation speed of a polygon motor for rotating the polygon mirror.   The control unit includes means for causing the image forming unit to create a correction patch toner image for correcting a process condition at a predetermined timing, and the timing of the image magnification adjustment and the generation of the correction patch toner image is 6. The sheet feeding timing of the succeeding sheet is controlled based on a time required for adjusting the image magnification and a time required for generating the correction patch toner image when overlapping between the same sheets. Image forming apparatus.   The control unit determines whether or not a time obtained by adding the time required to adjust the image magnification and the time required to create the correction patch toner image exceeds a predetermined sheet interval, and determines that the time exceeds the predetermined time. A correction patch toner image is controlled not to be created, or a paper interval that can be processed by both is calculated, and a feeding timing of the subsequent paper is controlled based on the calculated paper interval. 6. The image forming apparatus according to 6.   Whether or not the correction patch toner image is created and corrected when the time required for the image magnification adjustment and the correction patch toner image creation time exceeds a predetermined paper interval. The image forming apparatus according to claim 7, further comprising an inter-paper correction execution enable / disable setting unit for the user to set the above.   The measurement unit according to claim 5, further comprising: a measurement unit configured to measure a time required for image magnification adjustment between the image adjustment magnification of the front surface and the image adjustment magnification of the back surface set in each of the paper feed trays by rotating the polygon motor. Image forming apparatus. The storage unit stores a preset fixing target temperature for each sheet feeding tray as a control value in association with each sheet feeding tray, and also stores a fixing target temperature difference and a time required for adjusting the temperature difference. Memorize it,
The control unit includes a difference between a fixing target temperature stored in association with the paper feed tray loaded with the preceding paper and a fixing target temperature stored in correspondence with the paper feed tray loaded with the subsequent paper. 4. The image forming apparatus according to claim 3, wherein a time required for adjusting the fixing target temperature for the succeeding sheet is specified based on the control unit, and the sheet feeding timing of the succeeding sheet is controlled based on the specified required time.

Images