JP4529506B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an improvement of an image forming apparatus that can adjust an output image position with respect to a sheet.

Conventionally, as an image forming apparatus (output device) mainly used in the commercial printing market, an electrophotographic technique, an ink jet technique, and an offset printing technique has been widely used as an output technique that is widely used in the world.
In the case of the output device adopting the former electrophotographic technology or ink jet technology, a regular cut paper such as A3 size or A4 size is often used, and in the case of the latter offset printing, after output to a large size such as chrysanthemum size or 46 format. In general, a cutting process is performed.
When creating final production goods in these various cases, after the output production goods are output, the final production goods are processed through paper folding, cutting, and bookbinding.

Here, when the final product 150 after binding is taken as an example, as shown in FIG. 13A, for example, as a user who uses the position of the image on the sheet with respect to the edge of the sheet, it is between pages. When you are different, you often feel uncomfortable. For example, the page number Gp is always written at the four corners of each page, or the title is often written at the edge of the paper, but this position is close to the edge of the paper. If it is output to a different position, it is easy to feel the difference between the positions.
Similarly, in the case of a pamphlet enclosed with direct mail or a product guide, the position of the image with respect to the edge of the sheet or the folding position is easily felt.

  On the other hand, in the case of drawings, illustrations, etc., it is required that the specified positional relationship of the output image is the specified distance and positional relationship. For example, as shown in FIG. 13B, when a package 160 such as a label attached to a CD or cassette tape case is taken as an example, the positional relationship of lines indicating the cutting or folding position is created as the image data is created. Otherwise, it will not fit well in the case, or if it is put in the other way, there will be a gap and the appearance will be bad, and in the worst case it will be a defective product. Therefore, in this case, the accuracy of the positional relationship between the images G1 to G3 is required to be stricter than the positional accuracy with respect to the above-described paper edge.

As a conventional image position control method of an image forming apparatus, for example, a recording material (sheet) used in the image forming apparatus, that is, a so-called output paper traveling position is detected, and an image writing position is determined according to the deviation amount. Has already been proposed (see, for example, Patent Document 1) that enables switching between a mode for determining an image and a predetermined write position mode determined in advance.
Furthermore, a technique has already been proposed that makes it possible to adjust the variation in image forming position with respect to paper in each paper feed tray (see, for example, Patent Document 2).
Furthermore, a technique for correcting the registration error of an image after the position of a sheet is determined by adjusting the position of a detection sensor has been proposed (see, for example, Patent Document 3).

JP 2001-125440 A (column of embodiment of the invention, FIG. 2) JP-A-8-1115011 (Example column, FIG. 2) Japanese Patent Laid-Open No. 6-127038 (Example column, FIG. 2)

For example, if any prior art of Patent Documents 1 to 3 is applied, as shown in FIG. 13B, for example, when outputting the package 160, it may be possible to output the created image faithfully. .
However, as shown in FIG. 13 (a), it is said that the conventional image position control method (a technology that faithfully outputs the positional accuracy between images) cannot cope with the positional deviation of the image near the edge of the sheet. A technical challenge has been found.
This is presumed to be due to the expansion and contraction of the sheet (paper) output through a series of image forming processes.
This point will be described in detail. For example, in the case of the electrophotographic technique, the toner is melted in the fixing process, and thus heat must be applied to the paper. At that time, the paper expands and contracts due to heat during the fixing process. In addition, in the case of offset printing, a solvent referred to as “pump water” is often used in order to smoothly distribute ink into a printing apparatus (comprising a printing unit for each color component). At this time, since the sheet absorbs moisture by the solvent, the sheet expands every time it passes through each printing unit. Therefore, as described above, the image position control method that faithfully outputs the position accuracy between images cannot improve the image position accuracy with respect to the sheet edge.

Further, when considering an output application (for example, bookbinding) as shown in FIG. 13A, as described above, since the user feels sensitive to the image position accuracy with respect to the paper edge, the image position accuracy with respect to the paper edge is low. Very important.
Now, using an electrophotographic copying machine and an offset printing machine, respectively, the 95% confidence limit value (average value + 1.96σ) obtained by measuring the size of 20 sheets after output (here, the A3 size in the longitudinal direction and the transverse direction). ) Is shown in FIG.
According to the figure, in the longitudinal direction of the A3 size, 0.8 mm in the case of an electrophotographic copying machine, 0.6 mm in the case of an offset printing machine, deviates from a specified value (A3 size: 297 mm × 420 mm). This is due to the cutting accuracy of the paper and the expansion and contraction of the paper during output.
Therefore, as long as there is such a deviation from the specified value of the paper size, it is impossible to output an image with an image position accuracy that does not make the user feel uncomfortable in the case described above (for example, bookbinding).

  The present invention has been made to solve the above technical problem, and can correct the output size of an image in accordance with the amount of expansion and contraction of the sheet and maintain good image position accuracy with respect to the sheet edge. An image forming apparatus is provided.

The present inventor has devised the present invention and a reference invention related to the present invention in accordance with whether or not the cutting process is performed after the image forming process by the image forming unit.
First, as shown in FIG. 1A, the reference invention related to the present invention includes an image forming unit 1 capable of forming an image G on a sheet S. The image forming unit 1 includes an image G on the sheet S. An image forming apparatus that has a fixing unit 5 that can be heated and fixed, and that outputs a sheet S image-formed through a series of image forming processes without cutting. The sheet size determining means 2 for determining the sheet size corresponding to the length information of the four sides of the sheet S after the series of image forming processes by the image forming unit 1 is completed, and the sheet size determining means 2 An output for calculating an output magnification to be corrected based on a four-side adjustment amount comprising a ratio between the determined sheet size and a sheet size prescribed value corresponding to the length of the four sides of the sheet S of a predetermined sheet size. The magnification calculation of the output image by the image forming unit 1 based on the calculation result of the rate calculation means 3 and the output magnification calculation means 3, and the output magnification correction in which the edge image positions relative to the four sides of the sheet S can be set relatively equal Means 4 is provided.

The reference invention related to the present invention is premised on a mode in which the sheet S is output without being cut after a series of image forming processes.
This mode includes various image forming methods such as an electrophotographic method, an electrostatic recording method, and an ink jet recording method. In this reference invention , the image G on the sheet S can be heat-fixed as the image forming unit 1. A mode in which the fixing unit 5 is provided is employed. That is, the sheet S is expanded or contracted (expanded or contracted) by the fixing unit 5, and the technical problem (image shift) is likely to occur. This aspect is particularly effective.

In addition to the mode using the sheet size detection unit, the sheet size determination unit 2 includes a mode in which the sheet size measured using a UI or the like is input and the sheet size is determined based on this.
Here, as an aspect in which the sheet size detecting means is used for the sheet size determining means 2, the sheet size detecting means that can detect the sheet size after a series of image forming processes by the image forming unit 1 is completed. One that determines the sheet size based on the information detected by the size detection means is mentioned.

The output magnification calculation means 3 may be selected as appropriate as long as the output magnification can be calculated. However, as a typical aspect, the output magnification calculation means 3 can be selected with respect to the two directions of the sheet feeding direction and the sheet width direction perpendicular thereto. One example is to calculate an output magnification to be corrected two-dimensionally.
Furthermore, the sheet size specified value may be any value that uses the specified size information of the selected sheet S. Normally, the standard sheet size information is used, but even a non-standard sheet size can be used as a sheet size specified value if a specified size is input in advance. In addition, the sheet size specified value may be individually detected, but in this case, the specified value includes an error in size detection. Can be
Furthermore, the output magnification correction means 4 may be appropriately selected as long as it corrects the output magnification based on the information of the output magnification calculation means 3.

Next, the present invention will be described . In the present invention , as shown in FIG. 1B, the image forming unit 1 capable of sequentially forming the respective color component images on the sheet S and the downstream of the image forming unit 1 in the sheet conveying direction. The image forming unit 1 includes a plurality of printing units 6 (for example, 6a to 6d) capable of sequentially forming the respective color component images on the sheet S. An image forming apparatus that outputs the sheet S on which each color component image has been formed by each printing unit 6 after cutting the sheet S to a predetermined size by the cutting mechanism 10, and an image forming process of each color component image by the image forming unit 1. The image output position determining means 7 for determining the output position of each color component image corresponding to the length information of the four sides of each color component image area on the sheet S after the image processing is completed, Among the determined output positions of each color component image, other colors with respect to the output magnification of the reference color image based on the image area four-sided adjustment amount composed of the ratio between the output position of the reference color image and the output position of the other color component image Output magnification calculation means 8 for calculating the output magnification to be corrected of the component image, and the magnification correction of each color component image by the image forming unit 1 based on the calculation result of the output magnification calculation means 8, and the output position of each color component image Are provided with output magnification correction means 9 that can be set relatively equally.

This mode is premised on a mode in which the sheet S is cut and output after a series of image forming processes.
In this aspect, there are various image forming methods. In the present invention, the image forming unit 1 includes a plurality of printing units 6 (for example, 6a to 6d) capable of sequentially forming each color component ink image on the sheet S. The thing is adopted.
In each printing unit 6, a solvent referred to as water is used to control the ink fixing state on the plate cylinder, so that the sheet S extends each time it passes through each printing unit 6. Thus, the technical problem (image shift) of this case is likely to occur, and this aspect is particularly effective.
Furthermore, in this embodiment, the sheet size extension is finally handled by cutting. However, since color misregistration occurs due to misregistration of each color component image, the output position of each color component image with respect to the sheet S is individually determined. It is necessary to correct the magnification.

The image output position discriminating means 7 typically includes an aspect in which the image output position detecting means 11 is used. An image output position measured using a UI or the like is input, and image output is performed based on the input image output position. A mode for discriminating the position is also included.
Here, as an aspect of using the image output position detecting means 11 for the image output position determining means 7, an image output position detecting means capable of detecting the output position of each color component image after the image forming process of each color component image is completed. 11 (specifically, 11a to 11d), which determines the output position of each color component image based on the information detected by the image output position detecting means 11. For example, the image output position detecting means 11 outputs a ladder pattern to detect the image output position, outputs a grid pattern to detect the output image position, or is called “dragonfly”. The image output position may be determined by detecting the mark position.

Further, the output magnification calculation means 8 may be selected as appropriate as long as the output magnification can be calculated. However, as a typical aspect, the output magnification calculation means 8 is in two directions, ie, the sheet feeding direction and the sheet width direction orthogonal thereto. There is a mode in which the output magnification to be corrected two-dimensionally for each color component image is calculated.
The output magnification correction means 9 may be appropriately selected as long as it corrects the output magnification of each color component image based on the information of the output magnification calculation means 8.

According to the present invention, mode of outputting the sheet which each color component images in each printing unit has been formed and having a plurality of printing units each color component image is available sequentially formed on the sheet after cutting to a predetermined size by cutting mechanism Then, the output size of each color component image is corrected based on the image area four-side adjustment amount calculated according to the expansion / contraction amount of the sheet, and the output position of each color component image can be adjusted with high accuracy. Even if the image is mainly expanded), the position of each color component image can be relatively aligned, and accordingly, color overlap of each color component image can be reliably realized, and an image that does not feel uncomfortable for the user can be formed. it can.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 is an explanatory diagram showing the overall configuration of the first embodiment of the image forming apparatus to which the reference invention related to the present invention is applied.
In FIG. 1, an image forming apparatus 15 includes a printer unit 20 capable of forming a color image on a sheet (paper in this embodiment), and a scanner (IIT: Image Input Terminal) installed on the upper part of the printer unit 20 for reading a document. Abbreviation) 26.
The printer unit 20 includes an image forming module 21 inside the housing, and multi-stage sheet supply trays 31 to 34 are disposed below the image forming module 21, and a multi manual feed tray (MSI) is provided on the side of the housing. : Multi Sheet Inserter) 35 is arranged to be freely opened and closed. On the other hand, as the scanner 26, for example, an optical unit 262 that reads an original on the platen 261 and takes it into an image sensor 263 such as a CCD is used. An original feeding device 27 for feeding the original is placed above the scanner 26. Is arranged.

The image forming module 21 used in the present embodiment employs, for example, an electrophotographic system, and includes a photosensitive drum 22 that forms and supports each color component toner image, and each color component on the photosensitive drum 22. The toner images are sequentially primary transferred onto the intermediate transfer belt 23, and the multi-color component toner image on the intermediate transfer belt 23 is secondarily transferred onto the recording sheet by the secondary transfer device 24 including, for example, a secondary transfer roll, and the fixing device 25. It is intended to lead to.
Here, around the photosensitive drum 22, a charger 221 for charging the photosensitive drum 22, and an exposure device (raster output scanning optical system) 222 such as a laser scanning device for writing an electrostatic latent image on the photosensitive drum 22 are provided. A developing device 223 that stores each color component toner and visualizes the electrostatic latent image on the photosensitive drum 22; and transfers each color component toner image on the photosensitive drum 22 onto the intermediate transfer belt 23, for example, a transfer roll An electrophotographic device such as a primary transfer device 224 and a cleaner 225 for cleaning residual toner on the photosensitive drum 22 are sequentially arranged.
The intermediate transfer belt 23 is stretched and circulated on a plurality of stretching rolls, and the secondary transfer device 24 is disposed opposite to each other with one stretching roll as a backup roll. Reference numeral 231 denotes a cleaner for cleaning the intermediate transfer belt 23.
Further, the fixing device 25 may be appropriately selected as long as it has a known configuration. For example, a heating fixing roll and a pressure fixing roll are brought into contact with each other, and a halogen lamp is provided inside the heating fixing roll. Such a heat source is incorporated, and a pressure fixing roll is press-contacted to the heat fixing roll with a predetermined pressure so as to form a predetermined fixing nip region.

Furthermore, in the present embodiment, the conveyance path 40 from the sheet supply trays 31 to 34 is directed upward from the side of the casing on the side of the MSI 35 and discharged through the secondary transfer portion of the image forming module 21 and the fixing device 25. A main conveyance path 41 toward the tray 52 side, a reverse conveyance path 42 that is provided in a substantially Y shape on the lower side near the exit of the main conveyance path 41 and conveys the recording sheet by reversing the front and back of the recording sheet, and the reversal There is provided a return conveyance path 43 that is connected to a part of the conveyance path 42 and returns the recording sheet with the front and back reversed to the main conveyance path 41 in front of the image forming module 21 again.
Here, on the upstream side of the secondary transfer portion of the main transport path 41, a registration roll 44 that transports the recording sheet after positioning is provided, and on the downstream side of the secondary transfer portion, a transport belt 45 that transports to the fixing device 25 is provided. Each transport path 40 is provided with an appropriate number of transport rolls 46. A reversing mechanism 60 for reversing and transporting the front and back of the recording sheet is disposed in the reversing transport path 42.

In the present embodiment, the control device 100 is configured by a microcomputer including a CPU, a ROM, a RAM, and an I / O interface, for example, as shown in FIG. Various control programs including an image forming program (for example, a latent image forming program for the exposure device 222) are stored in the ROM, and a paper size sensor 101 is disposed in the main conveyance path 41 after the fixing device 25. Has been. For example, as shown in FIG. 3B, the paper size sensor 101 includes an image sensor that extends in a direction orthogonal to the sheet conveyance direction in order to grasp the overall size of various sizes of paper. ing.
The CPU executes an image forming program, for example, and sends predetermined control signals to various devices including the exposure apparatus 222 and various trays (accommodating trays 31 to 34 and manual feed tray 35) to form and develop a latent image. A series of image forming processes including transfer, fixing and the like.
In particular, in the present embodiment, the control device 100 receives detection information from the paper size sensor 101, performs a series of output image magnification correction processes as shown in FIG. 4, for example, and performs exposure processing 222 (laser 251, polygon 251). The exposure area by the mirror 252, that is, the latent image forming area Z on the photosensitive drum 22 is corrected (for example, the correction magnification is applied to the reference latent image forming area Z ′ in the main scanning direction and the sub scanning direction, respectively. Correction).
The control device 100 is provided with a scanner 26 and a UI (User Interface) 102.

Next, the operation of the image forming apparatus according to the present embodiment will be described.
Now, as shown in FIGS. 2 and 3, when a user sets a document on the document feeder 27 of the image forming apparatus 15 and then turns on the copy button (copy start), a series of image forming processes is performed by a copy start signal. Is done.
At this time, after each color component image is sequentially formed by the image forming module 21, the image on the intermediate transfer belt 23 is transferred to the paper S by the secondary transfer device 24, and then the paper S on which the image is transferred. Is discharged to the discharge tray 52 through the fixing device 25.
In such an image forming process, when the paper S passes through the fixing device 25, the paper S expands and contracts due to the heat of the fixing device 25, and the positional relationship between the paper S and the entire image is likely to be shifted.

Under such circumstances, in the present embodiment, the control device 100 performs output image magnification correction processing as shown in FIG.
In FIG. 3, as shown in FIGS. 3A and 3B, the control device 100 displays size information of the paper S after passing through the fixing device 25 (P1 to P4: length information of four sides of the paper S). ) From the paper size sensor 101.
Then, the control device 100 determines the ratio between the paper size detection values (P1 to P4) and the paper size prescribed value (for example, the length of four sides of the standard paper size A3 size: A3 (1) to A3 (4)), that is, The four-side adjustment amount Pi / A3 (i) is calculated.
Thereafter, the control device 100 performs mapping conversion as shown in FIG. 6 by multiplying the output image data Image (O) by the four-side adjustment amount Pi / A3 (i).

More specifically, now, for example, P3 of the detection values (P1 to P4) of the paper size is set to a predetermined amount Δy (for example, 0.8 mm extended) with respect to a predetermined value in the paper longitudinal direction, and to a specified value in the short direction. On the other hand, if a predetermined amount Δx (Δx <Δy) is deviated, the 600 dpi output device has a correction amount of 19 pixels, and the image may be extended and corrected by 19 pixels.
Now, the mapping conversion as shown in FIG. 6 will be described. The image data Image (x, y) at the coordinates (x, y) may be transferred to the coordinates (x, y + 19). When correcting 0.8 mm, one end of the A3 size paper is used as the reference end, and the opposite end of the A3 size paper (longitudinal dimension: 420 mm) has 19 pixels (corresponding to Δy) at the end in the longitudinal direction. The correction amount is 13 pixels (corresponding to Δx) at the short direction end of the direction dimension (297 mm). Then, in the image plane of the A3 size paper, linear position correction may be performed using the image position correction table shown in FIG. Here, since the image position correction table is 19 pixels with respect to the dimension in the longitudinal direction of the A3 size paper, a table in which this is allocated according to the length-size ratio is created. For example, about 13 pixels at a location of 297 mm This is the correction amount.

That is, the bitmap data decomposed according to the respective output resolutions may be subjected to processing (see FIG. 6) for expanding the image G from the reference size image G ′ by correction pixels as shown in FIG. It is an extremely simple process and there is no concern that the processing time will increase.
By such correction processing, each image is subjected to expansion processing (or contraction processing) at a predetermined magnification in the paper conveyance direction and the direction orthogonal thereto. As a result, the image edge positions are shifted with respect to the four sides of the sheet by substantially the same amount of shift. At this time, if the image edge position is a shift amount of, for example, about 0.3 mm with respect to the four sides of the paper, it is difficult for the user to visually recognize the image position shift, and substantially satisfies the allowable level of the user.
Conventionally, when the output image position is not aligned with the edge of the paper, a process of cutting the paper after output has been performed. However, the output image magnification correction as in the present embodiment has been performed. As a result, the secondary effect of eliminating the conventional cutting process is also expected.
In this embodiment, the paper size sensor 101 detects the paper size after fixing. However, the present invention is not limited to this. For example, the paper after fixing is read by the scanner 26. Alternatively, the paper size after fixing may be measured and input using the UI 102.

Embodiment 2
FIG. 8 shows Embodiment 2 of an image forming apparatus to which the present invention is applied.
In the same figure, unlike the first embodiment, the image forming apparatus 120 is an offset printing machine. For example, a plate created by a plate making output device or a printing plate output device (CTP) is used as the printing units 121 to 124 for each color component. The print processing is sequentially performed for each color component. That is, in the case of process color printing, for example, KCMY four-color plates are created, and the plates are set on the plate cylinders of the printing units 121 to 124, respectively. A cutting mechanism 125 is provided at the subsequent stage of each printing unit 121-124.
Further, in each of the printing units 121 to 124, a solvent referred to as “water feed” is used for the purpose of controlling the fixing state of the ink in each plate cylinder, so that the paper absorbs moisture and expands.
Therefore, in the present embodiment, the sheet is expanded every time it passes through the respective plate cylinders in the order of K, C, M, and Y.
In particular, in the present embodiment, since the amount of paper expansion differs for each color component, it is necessary to correct this.

In the present embodiment, as shown in FIG. 8, a control device 130 that corrects the image output magnification of each printing unit 121 to 124 is provided, and this control device 130 is provided downstream of each printing unit 121 to 124. Image position sensors (for example, constituted by image sensors) 131 to 134 are arranged, information from these image position sensors 131 to 134 is taken in, and output image magnification correction processing as shown in FIG. 10 is performed.
More specifically, each of the image position sensors 131 to 134 reads a ladder chart of each color component (K, C, M, Y), for example, as shown in FIG. The outputs of the position sensors 131 to 134 are taken in, and, for example, the difference d (d _M , d _C , d _Y ) between the reference color (black) image and the other three colors is obtained. At this time, as the measurement points SP by the image position sensors 131 to 134, for example, as shown in FIG. 9B, a suitable number may be set in the image portion so that the size of the image portion can be understood. In this example, SP (1) to SP (i) to SP (n), for example, 150 points are selected.
The detection operation by the image position sensors 131 to 134 is not limited to the measurement point SP described above. For example, as shown in FIG. 9B, the positions of the registration marks TM1 and the registration marks TM2 in the corner portions are detected. The image position may be determined based on this position.

Thus, as shown in FIG. 10, the control device 130 detects the image sizes Q1 to Q4 (see FIG. 9B) of each color based on the information from the image position sensors 131 to 134.
Thereafter, the control device 130 determines the ratio of the detected color component image sizes Q1 to Q4 with respect to the black image sizes A3 (1) to A3 (4) when the reference value of the image, for example, a black image is used as a reference. Based on this, the image area four-sided adjustment amount (correction value) Qi / A3 (i) of each color is calculated. At this time, the image area four-side adjustment amount of each color is determined as the output magnification of the image with respect to the black image as the reference color.
As a correction value calculation method, a line pattern of 6000 pixels is output by an output device of 600 dpi, for example, and the correction value is calculated by taking the ratio between the length of the line pattern (for example, 254 mm) and its detection distance. It may be.
Thereafter, the control device 130 may perform mapping conversion by multiplying the output image data Image (O) by the image area four-side adjustment amount Qi / A3 (i) of each color.
Although the black image is used as a reference, the output magnification of the black image itself may be corrected with respect to the absolute reference size.

If such correction of the output image is performed, for example, as shown in FIG. 11, since the shift amount of each color component image is obtained with respect to the black image as the reference color, the output magnification of each color component image is set to black. A two-dimensional correction magnification is calculated for each of the paper feed direction and the vertical direction based on the image, and each color component image is output according to the correction magnification.
As a result, even if the paper that has passed through each of the printing units 121 to 124 is expanded due to water, the black image and each color component image are output to the paper at relatively equal positions.
Here, to supplement FIG. 11, FIG. 11 shows the measurement of the shift amount of the color component images of the CMY colors with reference to the K color for four consecutive printed materials.
In the figure, the horizontal axis of the graph indicates the position of the printing press in the blanket axis direction (the number is the target NO). Since the printing press was adjusted so that the amount of deviation was zero at the center of the image, it was zero near the center. Since the direction from OUT to IN is a positive sign, it indicates positive on the IN side and negative on the OUT side due to paper expansion and contraction.

In the above embodiment, the output positions of the respective color component images are detected by the image position sensors 131 to 134. However, the present invention is not limited to this, and the user measures the output position offline, and the UI 140 It does not matter if the measured value is input at.
Further, in each of the first and second embodiments described above, if the individual paper sizes to be transported or the positional relationship of the output images are sequentially corrected while the image forming apparatus is operating, the output variation of each sheet. Can be corrected, and the image quality of the output can be improved.

Using the image forming apparatus model according to Embodiment 1, the dimensional relationship between the sheet edge and the image position was examined, and the result shown in FIG. 12 was obtained. As a comparative example, the registration misalignment amount was measured for each of the modes in which the images were aligned at the two ends of the paper, the lead side (leading end side) and the side registration side (right side with respect to the paper traveling direction). .
According to FIG. 12, in the comparative example, the paper edge and the image position are greatly deviated from the tail side (rear edge side) and the left side, but in this embodiment, the paper edge on the four sides of the paper It has been found that the amount of deviation from the image position is set to be approximately the same (about 0.3 mm).
At this time, if the amount of deviation is 0.3 mm with respect to all four sides of the sheet, it is difficult for the user to visually recognize the positional deviation of the image, which substantially satisfies the allowable level of the user.
Refer to FIG. 5 for the paper register items in FIG.

(A) is explanatory drawing which shows the outline | summary of the image forming apparatus which concerns on the reference invention relevant to this invention, (b) is explanatory drawing which shows the outline | summary of the image forming apparatus which concerns on this invention. 1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to a first embodiment to which a reference invention related to the present invention is applied. FIG. (A) is explanatory drawing which shows the control system of the image forming apparatus which concerns on Embodiment 1, (b) is B detailed drawing of (a), (c) is C detailed drawing of (a). FIG. 3 is an explanatory diagram schematically showing processing contents of a control system used in the first embodiment. It is explanatory drawing which shows each part dimension of an output paper. FIG. 5 is an explanatory diagram schematically showing mapping conversion processing performed in the first embodiment. 6 is an explanatory diagram illustrating an example of an image position correction table used in the first embodiment. FIG. It is explanatory drawing which shows the whole structure of the image forming apparatus which concerns on Embodiment 2 to which this invention was applied . (A) is explanatory drawing which shows the principle which detects the position shift of each color component image of an output paper, (b) is explanatory drawing which shows the measurement point of image position shift. FIG. 10 is an explanatory diagram schematically showing the processing contents of a control system used in the second embodiment. It is explanatory drawing which shows the detection result of the image position shift of each color component image. It is explanatory drawing which shows the improvement effect of the paper registration precision which concerns on an Example. (A) (b) is explanatory drawing of the output use which wants to obtain | require exactly the output position of an image. It is explanatory drawing which shows the paper size precision after offset printing and the output by an electrophotographic copying machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming unit, 2 ... Sheet size discrimination | determination means, 3 ... Output magnification calculation means, 4 ... Output magnification correction means, 5 ... Fixing unit, 6 (6a-6d) ... Printing unit, 7 ... Image output position discrimination means, 8: Output magnification calculating means, 9: Output magnification correcting means, 10: Cutting mechanism, 11 (11a to 11d) ... Image output position detecting means, G: Image, S: Sheet

Claims (3)

An image forming unit capable of sequentially forming each color component image on the sheet; and a cutting mechanism provided on the downstream side of the image forming unit in the sheet conveying direction and for cutting the sheet into a predetermined size. An image forming apparatus that has a plurality of printing units capable of sequentially forming component images and outputs a sheet on which each color component image is formed in each printing unit after cutting the sheet into a predetermined size by the cutting mechanism,
Image output position determining means for determining the output position of each color component image corresponding to the length information of the four sides of each color component image area on the sheet after the image forming process of each color component image by the image forming unit is completed;
Of the output positions of each color component image determined by the image output position determination means, the reference color is based on the image area four-sided adjustment amount comprising the ratio between the output position of the reference color image and the output position of the other color component image. An output magnification calculating means for calculating an output magnification to be corrected of another color component image with respect to an output magnification of the image;
Output magnification correction means capable of correcting the magnification of each color component image by the image forming unit based on the calculation result of the output magnification calculation means, and enabling the output positions of the respective color component images to be set relatively equal to each other. An image forming apparatus. The image forming apparatus according to claim 1 .
The image output position discriminating means comprises image output position detecting means capable of detecting the output position of each color component image after completion of the image forming process of each color component image, and based on information detected by the image output position detecting means. An image forming apparatus for determining an output position of each color component image. The image forming apparatus according to claim 1 .
The output magnification calculating unit calculates an output magnification to be corrected two-dimensionally for each color component image with respect to two directions of a sheet feeding direction and a sheet width direction orthogonal thereto.

Images