JP2002099192A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the front-end timing of transfer paper even on a device which has the distance between the write position and transfer position of an image longer than the distance from the standby position to the transfer position of the transfer paper. SOLUTION: This image forming device which forms a latent image corresponding to image data on an image carrier, visualizes the latent image by development, and transfers the visualized image to the transfer paper has a carrying means which starts carrying the transfer paper toward the transfer position in specific timing after temporarily holding the transfer paper before transfer, a 1st detecting means 71 which detects the front-end position of the transfer paper being carried before it reaches the transfer position, a measuring means 101 which measures the time up to the detection timing of the 1st detecting means by being triggered with a conveyance start signal from the standby state, and a correction quantity calculating means 107 which calculates the difference between the measured time obtained from the measuring means and a logical time, determines the speed profile from the 1st detecting means to the transfer position according to data on the difference so that the time of arrival at the transfer position becomes constant, and controls the carrying speed of the transfer paper at the carrying means according to the speed profile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the standby position of the transfer paper to the transfer position. The present invention relates to an image forming apparatus capable of adjusting a bias, a deviation, and a magnification.

[0002]

2. Description of the Related Art (1) Timing control: In a conventional image forming apparatus, a leading edge and a side edge of a transfer sheet are detected by a sensor.
Control means such as a CPU controls (changes or determines) the timing of starting writing of the main scan and the sub-scan of the image to be transferred onto the transfer paper.

For this reason, in an image forming apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the standby position of the transfer paper to the transfer position, the transfer paper detecting means is set to write the image. In order to position the detection unit farther than the distance between the position and the transfer position, it is necessary to dispose the detection unit at a position closer to the sheet feeding position than the standby position. For this reason, there has been a problem that automatic correction is not possible for the tip timing.

(2) Deviation correction: In addition, the deviation of the transfer paper cannot be corrected up to the deviation generated during the detection because the conveyance distance after detection is long.

(3) Magnification correction: Further, with respect to magnification correction, in the prior art, it is necessary to temporarily interrupt the image forming operation to form a mark for adjusting the magnification and make corrections, during which the user has to wait. There was a problem. Also,
When a mark printed on a transfer sheet is actually detected, there is a problem that the transfer sheet is wasted for adjustment.

[0006]

The present invention relates to the above (1).
The present invention has been made in view of the problems (3) to (3), and has the following objects.

A first object of the present invention is to provide a transfer apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position. An object of the present invention is to provide an image forming apparatus capable of performing control.

A second object of the present invention is to provide an image forming apparatus capable of correcting even if a transfer sheet is newly misaligned after the misalignment is detected when the conveyance distance from the misalignment detection to the transfer is long. It is to provide a device.

A third object of the present invention is to prevent a user from waiting by forming a mark for adjusting the magnification by temporarily interrupting the image forming operation and wastefully using transfer paper. An object of the present invention is to provide an image forming apparatus capable of adjusting the magnification of an image on a transfer sheet.

[0010]

That is, the present invention for solving the above problems is as described below. (1) The invention according to claim 1 is an image forming apparatus for forming a latent image corresponding to image data on an image carrier, developing the latent image into a visible image by development, and transferring the latent image to transfer paper, A transfer unit for starting transfer of the transfer sheet toward the transfer position at a predetermined timing after the transfer sheet is once waited before transfer, and a first detection unit for detecting a leading end position of the transfer sheet being transferred before reaching the transfer position And a measuring means for measuring a time until a detection timing by the first detecting means with a transport start signal from a standby state as a trigger, and calculating a difference between an actual measurement time and a theoretical time obtained from the measuring means, A speed profile between the transfer positions is determined from the first detection means based on the difference data so that the arrival time at the transfer position is constant, and the transfer speed of the transfer paper in the transfer means is determined based on the speed profile. Compensating hands to control When an image forming apparatus characterized by having a.

According to the present invention, the time required for the leading end position of the transfer paper being transported to reach the transfer position is measured by using the transport start signal from the standby state as a trigger, and the actual measurement time obtained by the measurement is obtained in advance. The difference from the calculated theoretical time is calculated, the speed profile of the above-described measurement section is determined so that the time to reach the transfer position is constant, and the transfer speed of the transfer paper is controlled. It is desirable that the speed profile be set so as to have a specified transport speed just before the transfer position.

As a result, even in an apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position, it is possible to control the leading edge timing of the transfer paper. become.

(2) The invention according to claim 2 is an image forming apparatus for forming a latent image corresponding to image data on an image carrier, developing the latent image into a visible image by development, and transferring the latent image to transfer paper. An exposure unit for forming a latent image corresponding to the image data on the image carrier; an image data input unit for inputting the image data to the exposure unit at a predetermined timing; and A transfer unit that starts the transfer to the transfer position at a predetermined timing after waiting once, and a first unit that detects a leading end position of the transfer paper being transferred before reaching the transfer position.
Detecting means, a first memory for storing the detection result of the first detecting means for each print at least in a paper feed stage where the transfer paper is fed, and a sample number of the detection result in a certain paper feed stage When a predetermined number is reached, an average value of the detection results is calculated, and the input of the image data is performed based on the average value of the detection results so that the timing of the image on the image carrier and the transfer direction of the transfer paper coincide. Correction means for correcting the timing or the transfer start timing of the transfer paper from the standby position;
An image forming apparatus comprising:

In the present invention, the time required for the leading edge position of the transfer paper being transported to reach the transfer position is detected by using the transport start signal from the standby state as a trigger. At least, the transfer paper is stored separately in a paper feed stage where paper is fed, and when the number of samples of the detection result in a certain paper feed stage reaches a predetermined number,
An average value of the detection results is calculated, and based on the average value, image data input timing or transfer start of the transfer sheet from the standby position is performed so that the timing of the image on the image carrier and the transfer sheet in the transfer direction coincide. Control the timing.

As a result, even in an apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position, it is possible to control the leading edge timing of the transfer paper. become.

(3) The second aspect of the present invention is to detect the side edge position of the transfer paper being transported before reaching the transfer position.
Detecting means, a second memory for storing the detection result of the second detecting means at least for each paper feed stage where the transfer paper is fed, and a sample number of the detection result in a certain paper feed stage. When the predetermined number is reached, the average value of the detection results is calculated, and the main data of the image data is adjusted based on the average value of the detection results so that the timing of the image on the image carrier and the transfer paper in the main scanning direction match. 3. A correction means for controlling a writing timing in a scanning direction.
An image forming apparatus according to any one of the preceding claims.

According to the present invention, in addition to the operation of the second aspect, the detection result before the side edge position of the transfer paper being conveyed reaches the transfer position is transmitted to at least the paper feed stage where the transfer paper is fed for each print. When the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, an average value of the detection results is calculated, and the image on the image carrier is transferred based on the average value. The writing timing of the image data in the main scanning direction is controlled so that the timings of the paper in the main scanning direction match.

As a result, even if the transfer distance from the detection of the deviation to the transfer is long, and the deviation of the transfer paper occurs after the detection of the deviation, the deviation can be corrected. (4) The image forming apparatus according to claim 4, wherein the color toner image is formed by superimposing a plurality of color toners, and the color toner image is transferred to a transfer paper, and then fixed and output, and A mark adding means for adding a plurality of magnification correction marks at predetermined positions of image data using toner density data having low visibility among toners of a plurality of colors using toner having the lowest visibility, Third detecting means for detecting the distance between the marks for magnification correction printed in the main scanning direction and the sub-scanning direction, respectively,
A third memory for storing a detection result of the detection unit for each print at least in a paper feed stage where the transfer paper is fed;
When the number of samples of the detection result at a certain paper feed stage has reached a predetermined number, an average value of the detection results is calculated, and based on the average value of the detection results, the main image of the image on the image carrier and the transfer paper are transferred. Correction means for controlling the magnification of the image data in the main scanning direction and the rotation speed of the image carrier holding the toner image or the transfer speed of the transfer paper at the transfer position so that the magnifications in the scanning direction and the sub-scanning direction match; An image forming apparatus comprising:

According to the present invention, a plurality of magnification correction marks are added to predetermined positions of image data with toner density data having low visibility by using the toner having the lowest visibility among toners of a plurality of colors, and fixing. Later, the magnification correction mark printed on the transfer paper is detected by detecting the distance between the marks in each of the main scanning direction and the sub-scanning direction, and this detection result is divided for each print into at least the paper feeding stage where the transfer paper is fed. When the number of samples of the above detection result in a certain paper feed stage reaches a predetermined number, an average value of the detection result is calculated, and the image on the image carrier is transferred based on the average value. The magnification of the image data in the main scanning direction and the rotation speed of the image carrier holding the toner image or the transfer speed of the transfer paper at the transfer position are controlled so that the magnifications of the paper in the main scanning direction and the sub-scanning direction match. I have to.

As a result, there is no need to temporarily suspend the image forming operation and form a mark for adjusting the magnification to make the user wait, or to wastefully use the transfer paper. Can be matched.

(5) According to a fifth aspect of the present invention, in each of the detecting means in the case of forming a double-sided image, the detection result is set to the first side detection result for each sheet feeding stage when forming the first side image, and
3. The image forming apparatus according to claim 2, wherein the detection result is stored as a second surface detection result for each sheet feeding stage in each of the first and second surfaces when forming an image on the surface. An image forming apparatus according to claim 4.

(6) The invention according to claim 6, wherein the correction means executes each control from a job next to the job in which the detection is performed. An image forming apparatus according to any one of claims 1 to 3.

(7) The invention according to claim 7, wherein the detection result sampled in the memory is cleared when a paper feed stage is inserted or removed, or when power is turned on or off. An image forming apparatus according to any one of claims 2 to 4.

(8) In the invention described in claim 8, the correction means includes an average value Nav of detection results of the latest predetermined number N of samples.
5. The image forming apparatus according to claim 2, wherein a control amount is calculated by multiplying e and an average value Save of all detection results by a weighting coefficient. .

(9) The invention according to claim 9 is characterized in that, when the detection result exceeds a predetermined range, the correction means judges that the data is invalid data and does not store it in the memory. An image forming apparatus according to any one of claims 2 to 4.

According to a tenth aspect of the present invention, the transfer residual toner remaining on the image carrier of the mark for magnification correction is converted to the toner for detecting the distance between the marks in the main scanning direction and the sub-scanning direction. A fourth detection unit having sensitivity, wherein the correction unit controls the rotation speed of the image carrier using the detection result obtained by the fourth detection unit, and obtains the rotation speed of the image carrier obtained by the third detection unit. 5. The image forming apparatus according to claim 4, wherein the conveying speed of the conveying unit is controlled using the detection result. Note that the control of the transport speed in this case is preferably feedback control.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional block diagram showing each unit of the embodiment of the present invention for each function, and FIG. 2 is a mechanical configuration of each part of an image forming apparatus to which the embodiment of the present invention is applied and an arrangement of each sensor. FIG. FIG.
In FIG. 2 and FIG. 2, the same items are denoted by the same reference numerals.

In these figures, reference numeral 1 denotes an image carrier on which a latent image and a toner image are formed, and 2 and 3 denote image carrier driving rollers for driving the image carrier 1 at a predetermined speed.
Y is a charger for charging for Y (yellow) image formation, 10M is a charger for charging for M (magenta) image formation, and 10C is a charger for C (cyan) image formation. The charging unit 10K performs charging for forming a K (black) image.

20Y is a writing unit for performing exposure for forming a Y (yellow) image, and 20M is M (magenta).
Writing unit for performing exposure for forming an image of 20C
Is a writing unit that performs exposure for forming a C (cyan) image, and 20K is a writing unit that performs exposure for forming a K (black) image. Each of the writing units 20Y to 20K in FIG. 2 constitutes the exposure unit 20 in FIG.

30Y is a developing unit for developing a Y (yellow) image, 30M is a developing unit for developing an M (magenta) image, and 30C is a developing unit for forming a C (cyan) image. Is a developing device for performing development for forming a K (black) image.

A cleaning unit 40 removes unnecessary toner on the image carrier 1 and a fixing unit 50 fixes the toner image on the transfer paper by heat and pressure. Reference numeral 60 denotes a conveying unit that conveys the transfer paper, a second paper feed roller 61 that causes the transfer paper to wait once before the transfer and then starts the conveyance toward the image carrier 1 (transfer position) at a predetermined timing, and a transfer unit. Conveying roller 6 for conveying the paper at a transfer position with image carrier 1
2 is provided.

Reference numeral 71 denotes a pre-transfer passage sensor which constitutes first detecting means for detecting the leading end position of the transfer paper being conveyed before reaching the transfer position, and 72 designates the side end position of the transfer paper being conveyed to the transfer position. A deviation detection sensor constituting a second detection means for detecting before reaching, a first magnification detection sensor 73 for detecting a magnification from an interval between predetermined toner images on the transfer paper, and a predetermined magnification detection sensor 74 for the image carrier. This is a second magnification detection sensor that detects a magnification from an interval between toner images.

Reference numeral 100 denotes a C for performing various detections and controls.
It is a PU and includes various units described in the operation description of the following embodiments. Reference numeral 200 denotes an operation unit on which a user sets a paper feed tray and a single-sided / double-sided mode, and 300 denotes an R for temporarily storing various data.
AM and 400 are ROMs storing reference data for correction and control.

Here, the RAM 300 and the ROM 400 are shown as existing outside the CPU 100.
A configuration using a memory inside the PU 100 is also possible. Each unit in the CPU 100 in FIG. 1 may be configured by any of software, firmware, and hardware.

The above-described configuration of the image forming apparatus shown in FIGS. 1 and 2 includes all the sensors and units that can be used in all of the following first to third embodiments. Is included. Therefore, in order to realize any of the embodiments, it is possible to configure with the minimum sensors and means described in the following description of the operation. Although an example of an image forming apparatus that does not use an intermediate transfer body is shown here, the present invention can be applied to an image forming apparatus that uses an intermediate transfer body.

<First Embodiment> A first embodiment of the tip control will be described with reference to a time chart of FIG.

First, the CPU 100 operates the hard timer on the basis of the writing start in synchronization with the start of the Y sub-scanning writing signal (FIG. 3B), turns on the clutch of the second paper feed roller 61 and starts driving. (FIG. 3C).

Further, the hard timer is operated from the above-mentioned second paper feed ON (FIG. 3D), and the pre-transfer passage detecting sensor 73 detects the leading edge of the transfer paper (see FIG. The time until ON)) is measured by the arrival time measuring means 1
01 is measured by hardware.

Then, at the moment when the pre-transfer passage detection sensor 73 is turned on, an interruption of the CPU 100 is also generated, and the correction amount calculating means 107 reads the arrival time up to the pre-transfer passage detection sensor 73 in the control program and stores it in the ROM 400 in advance. The difference from the set theoretical time (the arrival time in an ideal state) is calculated.

Here, the correction amount calculating means 107 is a pre-transfer passage detecting sensor for correcting the difference (to prevent the difference from occurring) so that the arrival time at the transfer position in FIG. 2 is constant. The speed profile of the path from 73 to the transfer position is determined. According to this speed profile, the transport speed control unit 111 causes the transport unit 60 (second
This is fed back to the rotation speed of the paper feed roller 61).

For example, when the correction amount calculating means 107 determines that the rotation speed is lower than the theoretical value, the rotation speed (FIG. 4 ') is higher than the reference rotation speed of the second paper feed roller 61 (FIG. 4'). Is determined so that the above-described difference does not occur. In this speed profile, the reference speed is set before the transfer position (FIG. 4).
FIG. 4 is an example, and the speed profile has a different pattern depending on the magnitude and absolute value of the difference.

Although FIG. 2 shows an example of a color image forming apparatus, the embodiment relating to the leading end control can be applied to a monochrome image forming apparatus.

<Second Embodiment> In this second embodiment, as shown in FIG.
1 is provided. Then, a shift detection sensor 72 is provided downstream of the pre-transfer passage detection sensor 71 and before the transfer.
The shift detection sensor 72 detects the side end position of the transfer paper being conveyed before reaching the transfer position.

5 and FIG. 5 together with the configuration diagrams of FIGS.
The operation will be described with reference to the flowchart of FIG. Here, the detection of deviation will be described in particular. First, the shift detecting sensor 72 detects a shift state detected for each of a sheet feeding stage (not shown) and the front and back of the transfer sheet (FIG. 5S).
1). The deviation amount detecting means 102 obtains the deviation amount from the detection result and sends it to the sampling means 106. And
The sampling means 106 determines whether or not the detection result is within the normal range (S2 in FIG. 5).

If the shift state detected for each of the sheet feeding stage (not shown) and the front and back sides of the transfer sheet is within the normal range, the sampling means 106 stores it in the RAM 300 (FIG. 5).
Along with S3), the number of samples N for the stored data is incremented by 1 (S4 in FIG. 5). The total number of samples S is also incremented by one.

At this time, if the data is out of the predetermined range, it is determined as an abnormal value and is not stored in the memory (S2 in FIG. 5). In this way, by treating the abnormal value as invalid data, it is possible to increase the processing accuracy.

At this time, when the number N of samples reaches the predetermined number X ("YES" in S5 of FIG. 5), the correction amount calculating means 107 calculates the average value between the number N of samples as a part of the process for calculating the correction amount. Nave is obtained (S6 in FIG. 5), and N is cleared (S7 in FIG. 5). Similarly, an average value Save between the total number of samples S is obtained, and a target value A obtained by multiplying each by a weighting coefficient is derived. A = αNave + βSave, where α + β = 1, Next, the correction amount calculation means 107 calculates the target value A and RO
The preset theoretical value B stored in M400
Is obtained as a correction amount (FIG. 5S
6). In this case, the timing of the image on the image carrier 1 and the timing of the transfer paper in the main scanning direction match based on the correction amount.
The writing control unit 108 in the main scanning direction may control the writing timing of the image data in the main scanning direction based on the correction amount calculated by the correction amount calculating unit 107.

In the above manner, even when the conveyance distance from the detection of the deviation to the transfer is long and the deviation of the transfer paper is newly generated after the detection of the deviation, the correction can be performed.

The above description is based on the displacement detection sensor 7.
2, the same processing is performed on the leading end position detected by the pre-transfer passage detection sensor 71, and the correction amount calculating means 10 corrects the deviation.
7 obtains the difference value C and the correction amount, and adjusts the input timing of the image data by the image data input means 109 based on the correction amount so that the timing of the image on the image carrier and the transfer direction of the transfer paper coincide. Alternatively, the same effect can be obtained by controlling the transfer start timing of the transfer sheet from the standby position by the transfer restart unit 110. Accordingly, even in an apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position, it is possible to control the leading edge timing of the transfer paper. It is also possible to perform the correction by combining the control of the front end timing and the above-described offset correction.

By the above processing, the correction amount calculating means 1
It is preferable that the correction amount regarding the deviation and the leading end determined by 07 is set after the end of the currently executed print job, and is effective from the next print job. It is desirable that the correction be performed for each paper feed stage and for each of the front and back sides of the transfer paper.

The sampling means 106 is provided in the RAM 3
00, and the number of samples N,
S needs to be reset because conditions change when the paper cassette is inserted or removed, or when the power is turned off / on.

Although FIG. 2 shows an example of a color image forming apparatus, the embodiment relating to the offset correction can be applied to a monochrome image forming apparatus.

<Third Embodiment> Here, as a third embodiment, an image forming operation is temporarily interrupted to form a mark for magnification adjustment, and the user is made to wait.
An image forming apparatus capable of adjusting the magnification of an image on a transfer sheet without wasting the transfer sheet will be described.

In the color image forming apparatus shown in FIG.
In the full-color mode, a mark for magnification correction (see M1 to M4 in FIGS. 6A to 6C) is added to the image data and printed using toner toner having low visibility using yellow toner having low visibility.

Here, the toner density data with low visibility means a density that does not adversely affect the image. The density that can be read by a magnification detection sensor described later also means a density that can be read.

For example, as shown in FIG. 6 (c), the Z-shaped magnification correcting marks M1 to M1 in the transport direction.
M4 is formed at a predetermined density of the yellow toner described above. Also, in FIG. 6, a sensor valid signal (FIG. 6 (a)) that effectively handles the output of the sensor and a sensor A output (FIG. 6) generated when the marks M1 and M2 are detected by the sensor A.
(B)) and the sensor B output (FIG. 6 (d)) generated when the marks M3 and M4 are detected by the sensor B.

Then, the marks M1 to M4 for magnification correction printed on the transfer paper after fixing by the fixing unit 50 are read by the first magnification detection sensor 73 while illuminating with LEDs (not shown) or the like. The magnification detection means 103 calculates the distance between the marks in each of the main scanning direction and the sub-scanning direction with respect to the reading result, and detects magnification data. Then, the sampling means 106 divides the magnification data into at least the paper feed stage where the transfer paper is fed for each print, and
0 is stored.

The correction amount calculating means 107 calculates an average value of the detection results when the number of samples of the detection results in a certain paper feed stage reaches a predetermined number, and based on the average value, the image holding value is calculated. The magnification of the image data in the main scanning direction and the rotation speed of the image carrier holding the toner image or the transfer paper at the transfer position is adjusted so that the magnifications of the image on the body and the transfer paper in the main scanning direction and the sub-scanning direction match. The correction amount of the transport speed is calculated.
Then, based on this correction amount, the image data input means 1
09 and the conveyance speed control means 111 control the magnification of the image data in the main scanning direction and the rotation speed of the image carrier holding the toner image or the conveyance speed of the transfer paper at the transfer position.

This process is substantially the same as the process in the flowchart of FIG. 5 of the second embodiment.
In this case, the judgment of the normal data is based on FIG.
If the time between a and c and d and f is within the predetermined range and the number of pulses between a and c and d and f is one, it is determined to be normal. The magnification in the sub-scanning direction is determined by the ratio between the time detected between a and d and the theoretical time stored in the ROM 300 in advance. The magnification in the main scanning direction is between a and b and a′−
It can be obtained from the ratio of the difference between the distances b ′ and the theoretical distance between the sensors AB.

As a result, there is no need to temporarily suspend the image forming operation and form a mark for adjusting the magnification to make the user wait, or to wastefully use the transfer paper. Can be matched.

In order to perform more accurate magnification correction, the image carrier 1 corresponding to the marks M1 to M4 on the transfer paper is required.
The marks M1 to M4 formed by the transfer residual toner on the second
It is also desirable to perform detection with the magnification detection sensor 74. In this case, the transfer residual toner remaining on the image carrier 1 for the magnification correction marks M1 to M4 is detected by the second magnification detection sensor 74 between the marks in the main scanning direction and the sub-scanning direction. Then, the correction amount calculating means 107 controls the image carrier driving rollers 2 and 3 using magnification data based on the detection result obtained by the second magnification detecting sensor 74 (fourth detecting means in the claims). Controls the rotation speed of the image carrier 1. Then, together with this, using the detection result obtained by the first magnification detecting sensor 73 (third detecting means in the claims), the conveying means 60 (conveying roller 62)
Control the transport speed of the. Note that the control of the transport speed in this case is preferably feedback control.

[0062]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first aspect of the present invention, the time until the leading end position of the transfer paper being transported reaches the transfer position is measured by using the transport start signal from the standby state as a trigger, and the time is obtained by the measurement. The difference between the actual measurement time and the theoretical time calculated in advance is calculated, the speed profile of the above-described measurement section is determined so that the arrival time at the transfer position is constant, and the transfer speed of the transfer paper is controlled. . As a result, even in an apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position, it is possible to control the leading edge timing of the transfer paper.

(2) According to the second aspect of the present invention, the time until the leading end position of the transfer paper being transported reaches the transfer position is detected by using the transport start signal from the standby state as a trigger. This detection result is stored for each print in at least the paper feed stage where the transfer paper is fed, and stored.
When the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, an average value of the detection results is calculated, and based on the average value, the timing of the image on the image carrier and the transfer direction of the transfer sheet is determined. The input timing of the image data or the transfer start timing of the transfer sheet from the standby position is controlled so as to match. As a result, even in an apparatus in which the distance between the image writing position and the transfer position is longer than the distance from the transfer paper standby position to the transfer position, it is possible to control the leading edge timing of the transfer paper.

(3) According to the third aspect of the invention,
In addition to the above operation, the detection result before the side edge position of the transfer paper being transported reaches the transfer position is stored for each print in at least the paper feed stage where the transfer paper is fed. When the number of samples of the detection result in the row reaches a predetermined number, an average value of the detection results is calculated, and the timing of the image on the image carrier and the timing of the transfer paper in the main scanning direction match based on the average value. Thus, the writing timing of the image data in the main scanning direction is controlled. As a result, even when the transport distance from the detection of the deviation to the transfer is long, and the transfer paper is newly deviated after the detection of the deviation, the deviation can be corrected.

(4) According to the fourth aspect of the present invention, of the plurality of color toners, the toner having the lowest visibility is used, and a plurality of magnification corrections are performed at predetermined positions of the image data with toner density data having low visibility. Mark, and the distance between the marks for magnification correction printed on the transfer paper after fixing in the main scanning direction and sub-scanning direction is detected in each of the main scanning direction and the sub-scanning direction. When the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, an average value of the detection results is calculated, and based on this average value, the image is stored. The transfer paper at the rotational speed or the transfer position of the image carrier holding the toner image and the magnification in the main scanning direction of the image data so that the magnification of the image on the carrier and the transfer paper in the main scanning direction and the sub-scanning direction match. Control the transport speed of It has to. As a result, it is possible to adjust the magnification of the image on the transfer paper without temporarily suspending the image forming operation and forming a mark for adjusting the magnification to make the user wait, or wastefully using the transfer paper. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating an electrical configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a mechanical configuration of the image forming apparatus according to the embodiment of the present invention;

FIG. 3 is a time chart illustrating an operation of the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a time chart illustrating an operation of the image forming apparatus according to the first embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating an operation of an image forming apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 10Y to 10K Charger 20Y to 20K Writing unit 30Y to 30K Developing device 40 Cleaning unit 50 Fixing unit 60 Conveying means 61 Second paper feed roller 62 Conveyance roller 71 Pre-transfer passage detection sensor 72 Deviation detection sensor 73 1 magnification detection sensor 74 2nd magnification detection sensor 100 CPU 300 RAM 400 ROM

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G03G 15/04 G03G 15/04 120 15/16 103 F term (reference) 2H027 DA17 DA20 DA38 DA41 DC03 DC04 DE01 DE07 DE09 EA03 EB04 EC01 EC03 EC06 EC09 ED02 ED06 ED16 ED17 ED24 EE03 EE08 EF01 EF06 EF17 EH03 2H030 AA01 AD05 AD11 AD17 AD19 BB02 BB16 BB42 BB44 BB46 BB54 BB56 BB71 2H03 AB01 BA15 BA15 BA15 BA15 ABA02 BA15 BAA BB02 DA08 EA03 FA08

Claims (10)

[Claims] 1. An image forming apparatus for forming a latent image according to image data on an image carrier, developing the latent image into a visible image by development, and transferring the latent image to transfer paper, wherein the transfer paper is transferred before transfer. A transport unit for starting transport to the transfer position at a predetermined timing after waiting once, a first detecting unit for detecting a leading end position of the transfer paper being transported before reaching the transfer position, A measuring means for measuring a time until a detection timing by the first detecting means by using a transport start signal as a trigger; and calculating a difference between an actual measurement time and a theoretical time obtained from the measuring means, and an arrival time at the transfer position. Correction means for determining a speed profile between the transfer positions from the first detection means based on the data of the difference so that the difference is constant, and controlling the transfer speed of the transfer paper in the transfer means based on the speed profile. Have Image forming apparatus characterized by. 2. An image forming apparatus for forming a latent image corresponding to image data on an image carrier, developing the latent image into a visible image by development, and transferring the latent image to transfer paper, the latent image corresponding to the image data. Exposure means for forming an image on an image carrier; image data input means for inputting the image data to the exposure means at a predetermined timing; Conveying means for starting conveyance toward the transfer position; first detecting means for detecting a leading end position of the transfer paper being conveyed before reaching the transfer position; and a detection result of the first detecting means for each print. A first storage unit that stores the transfer paper divided into at least the paper feed stages where the transfer paper is supplied;
A memory, when the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, calculates an average value of the detection results, and based on the average value of the detection results, the image on the image carrier and the transfer paper; A correction unit that corrects the input timing of image data or the transfer start timing of the transfer paper from a standby position so that the timings of the transfer directions coincide with each other. 3. A second detecting means for detecting a side edge position of the transfer paper being conveyed before reaching the transfer position; and at least the transfer paper is fed for each print based on a result detected by the second detection means. A second memory that stores the data separately for each of the paper feed stages, and when the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, calculates an average value of the detection results, and calculates the average value of the detection results. 3. A correction means for controlling writing timing of image data in the main scanning direction such that the timing of the image on the image carrier and the timing of the transfer paper in the main scanning direction coincide with each other. Image forming device. 4. An image forming apparatus for forming a color toner image by superimposing a plurality of color toners, transferring the color toner image to a transfer sheet, and fixing and outputting the color toner image. Mark adding means for adding a plurality of magnification correction marks at predetermined positions in image data using toner density data having low visibility using toner having the lowest visibility, and the magnification printed on transfer paper after fixing. A third detecting unit for detecting a distance between the marks for correction in the main scanning direction and the sub-scanning direction in each of the scanning direction; A third memory for storing the data separately in stages, and when the number of samples of the detection result in a certain paper feed stage reaches a predetermined number, an average value of the detection results is calculated, and based on the average value of the detection results, Image bearer The magnification of the image data in the main scanning direction and the rotation speed of the image carrier holding the toner image or the transfer paper at the transfer position is adjusted so that the magnifications of the image on the body and the transfer paper in the main scanning direction and the sub-scanning direction match. An image forming apparatus comprising: a correction unit that controls a transport speed. 5. In each of the detecting means in the case of forming a double-sided image, a detection result is used as a first-side detection result for each sheet feeding stage when forming an image on the first side, and a detection result is used for each sheet feeding stage when forming an image on the second side. The method according to any one of claims 2 to 4, wherein the detection result is stored as a second surface detection result in each of the memories separately for the first surface and the second surface. Image forming device. 6. The image forming apparatus according to claim 2, wherein the correction unit executes each control from a job next to the detected job. 7. The apparatus according to claim 2, wherein the detection result sampled in the memory is cleared when a paper feed stage is inserted or removed, or when a power supply is turned on or off. The image forming apparatus as described in the above. 8. The control means calculates the control amount by multiplying the average value Nave of the detection results of the latest predetermined number of samples N and the average value Save of all the detection results by a weighting coefficient, respectively. 5. The method according to claim 2, wherein
The image forming apparatus according to any one of the above. 9. The data processing apparatus according to claim 2, wherein the correction unit determines that the data is invalid data and does not store the data in a memory when the detection result exceeds a predetermined range. An image forming apparatus according to any one of the above. 10. A method for detecting the distance between marks in the main scanning direction and the sub-scanning direction of the untransferred toner remaining on the image carrier of the magnification correction mark, the fourth toner having a sensitivity to the toner.
A detection unit, wherein the correction unit controls the rotation speed of the image carrier using a detection result obtained by the fourth detection unit;
The image forming apparatus according to claim 4, wherein a conveying speed of the conveying unit is controlled using a detection result obtained by the third detecting unit.