JP2009210886A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a user's convenience in determination of a displacement correction quantity of images formed on both sides of a paper. <P>SOLUTION: An image forming apparatus performs the following processing: preliminary forming processing for forming images of both sides of a document on both the sides of the paper based on image data obtained by reading both the sides of the document; positional relation measurement processing for measuring, based on image data obtained by reading one side of the same document after adjusting the light quantity of a light source provided within a document reading part so that show-through phenomenon is generated, a positional relation between a one-side image of the document and a reverse image reflected thereto, and measuring, based on image data obtained by reading one side of the paper after preliminary forming processing, a one-side image of the paper and a reverse image reflected thereto; and correction quantity calculation processing for calculating, based on the positional relations of the document with the one-side image and reverse-side image of the paper, a positional shift correction quantity of the images on both sides formed on the paper. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

 The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having not only a single-sided copy function of a document but also a double-sided copy function.

Conventionally, in an image forming apparatus having a copying function such as a copying machine, a problem has been pointed out that misalignment occurs in images formed on the front surface and the back surface of a sheet during duplex copying. In order to solve such a problem, for example, in Patent Document 1 below, images on both sides of a sheet on which registration marks “#” are printed at several positions on both sides are read, and “#” included in the images on both sides is read. There has been disclosed a technique for reducing the positional deviation between the images on both sides by obtaining the positional deviation correction amount from the positional relationship and correcting the paper placement position or the paper supply timing based on the positional deviation correction amount.
Japanese Patent Laid-Open No. 10-246992

  In the above prior art, in order to determine the amount of positional deviation correction of images formed on both sides of the paper, first, a registration mark “#” is printed on both sides of the paper other than the original that is the actual reading object, There is a problem that it is necessary to read images on both sides of the paper, which is inconvenient for the user.

The present invention has been made in view of the above-described circumstances, and provides an image forming apparatus capable of improving the usability of a user when obtaining a positional deviation correction amount for images formed on both sides of a sheet. For the purpose.

  In order to achieve the above object, the present invention provides, as a first solution means according to an image forming apparatus, a document reading unit that has a single-sided and double-sided reading function of a document and generates image data of a read image; An image forming apparatus comprising: an image forming unit that forms an image on one side and both sides of a sheet based on data; and a control unit that integrally controls the document reading unit and the image forming unit. Based on the image data obtained by reading both sides of the document, a pre-forming process for forming images on both sides of the document on both sides of the paper, and a show-through phenomenon of the light quantity of the light source provided in the document reading unit Measure the positional relationship between the single-sided image of the original and the back-side image reflected in the single-sided image due to the show-through phenomenon based on the image data obtained by reading one side of the same original On the other hand, based on the image data obtained by reading one side of the paper after the preliminary forming process, a position for measuring the positional relationship between the single-sided image of the paper and the back-side image reflected in the single-sided image due to the show-through phenomenon A relationship measurement process, and a correction amount calculation process for calculating a positional deviation correction amount of the double-sided image formed on the paper based on the measurement result of the positional relationship between the single-sided image and the backside image of the document and paper. It is characterized by performing.

    Further, as a second solving means related to the image forming apparatus, in the first solving means, the control unit performs the preliminary forming process, the positional relationship measuring process, and the correction amount calculating process every time the document is read. Total correction amount calculation mode for calculating the positional deviation correction amount for each original, and correction amount holding for holding the positional deviation correction amount calculated when one original is read until the next timing for updating the positional deviation correction amount. The mode is selectively switched.

    Further, as a third solving means relating to the image forming apparatus, in the second solving means, the control unit is configured to use the positional deviation correction amount calculated for each document in the total number correction amount calculation mode. In addition, positional deviation correction is performed for each original, and images on both sides of the original are re-formed on both sides of a new sheet for each original.

    Further, as a fourth solving means according to the image forming apparatus, in the second solving means, the control unit is configured to detect the positional deviation of the document based on the positional deviation correction amount held in the correction amount holding mode. Correction is performed, and images on both sides of the document are formed on both sides of the paper.

  In the image forming apparatus according to the present invention, in order to obtain the positional deviation correction amount of the image formed on both sides of the sheet, a specific symbol (for example, “#”) as in the past is printed on the sheet without actually printing it. Since the misregistration correction amount can be obtained using a document that is a reading object, it is possible to improve the usability of the user.

Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram of an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 is, for example, a multifunction machine having functions of a copier and a printer, and includes a central processing unit (CPU) 10, a read only memory (ROM) 11, a random access memory (RAM) 12, various sensor groups 13, and paper. A transport unit 14, an image reading unit 15, an image data storage unit 16, an image forming unit 17, an operation display unit 18, and a communication I / F unit 19 are provided. Reference numeral 200 denotes a PC (Personal Computer) for giving a print instruction to the image forming apparatus 100 from the outside.

  The CPU (control unit) 10 is input from the control program stored in the ROM 11, detection signals input from the various sensor groups 13, image data stored in the image data storage unit 16, and the operation display unit 18. Based on the operation signal, the print instruction signal received from the PC 200 via the communication I / F unit 19, and the image data for printing, the respective functional units in the image forming apparatus 100 are integratedly controlled.

 The ROM 11 is a non-volatile memory that stores a control program used by the CPU 10 and other data. The RAM 12 is a working memory used as a temporary storage destination of data when the CPU 10 executes a control program and performs various operations. The various sensor groups 13 are composed of various sensors necessary for image forming operations such as a paper out detection sensor, a paper position detection sensor, a temperature sensor, and the like, and various information detected by each sensor is detected by the CPU 10 as detection signals. Output. The paper transport unit 14 includes a transport roller for transporting paper stored in a paper tray (not shown) to the image forming unit 17 and a motor for driving the transport roller, and a paper after image forming processing to a paper discharge tray (not shown). It is composed of a conveying roller for conveying, a motor for driving the conveying roller, and the like.

 The image reading unit 15 is an ADF (Auto Document Feeder) that automatically feeds a document set on a document tray to a predetermined document reading position or an image that reads an image of a document conveyed to the document reading position under the control of the CPU 10. It consists of a sensor unit. Further, the image sensor unit includes a light source for illuminating the original with illumination light, a photoelectric conversion element (for example, a CCD (Charge Coupled Device) element) that receives reflected light of the illumination light and converts it into an analog voltage signal, An image data generation unit that generates image data of a read original by converting an analog voltage signal into a digital signal.

 Further, the image reading unit 15 reads one side (front side) of the document at the document reading position, and then reverses the document and reversely transports the document to the document reading position to read the back side. It has a function. In this way, instead of the method of reversing the original and reading both sides, the photoelectric conversion element (CCD) for single-sided reading and the photoelectric conversion element for backside reading (for example, CIS (Contact Image Sensor)) are used. A configuration may be adopted in which two are provided and both sides of the original are simultaneously read at the original reading position.

  The image data storage unit 16 is, for example, a flash memory, and stores image data generated by the image reading unit 15 in response to a write request from the CPU 10, while storing image data stored in response to a read request from the CPU 10. Output to. Under the control of the CPU 10, the image forming unit 17 applies a toner image to the paper conveyed from the paper conveying unit 14 based on the image data stored in the image data storage unit 16 and the image data for printing received from the PC 200. The toner image is transferred and the toner image is fixed (image formation). In addition, the image forming unit 17 has a function of forming a single-sided image of a document on one side of a sheet and then forming a back-side image of the document on the back side of the sheet by turning the sheet upside down. ing.

 The operation display unit 18 is configured by, for example, a touch panel, displays a screen for notifying various operation keys and various information under the control of the CPU 10, and operates operation input information of various operation keys displayed on the touch panel. It outputs to CPU10 as a signal. The communication I / F unit 19 is an interface for performing communication between the image forming apparatus 100 (specifically, the CPU 10) and an external PC 200, and is connected to the PC 200 via a network such as a LAN (Local Area Network). .

 Next, the operation of the image forming apparatus 100 according to the present embodiment configured as described above, particularly the misregistration correction operation when copying images on both sides of a document onto both sides of a sheet (duplex-duplex copying) is shown in FIG. This will be described with reference to the flowchart of FIG.

 As shown in FIG. 2, first, when the CPU 10 detects that a double-sided / double-sided copy instruction has been generated by the operation of the operation display unit 18 by the user (step S <b> 1), the CPU 10 displays the document reading unit 15 and the image data storage unit 16. Control is performed to read images on both sides of the document set on the document tray, and the image data on both sides of the document is stored in the image data storage unit 16 (step S2). Here, it is assumed that the one-side (front) image of the document is an image as shown in FIG. 3A and the back image is an image as shown in FIG.

Subsequently, the CPU 10 controls the paper transport unit 14 to transport the paper from the paper tray to the image forming unit 17, and reads the image data on both sides of the document read in step S <b> 2 from the image data storage unit 16. 17 is controlled to form images on both sides of the document on both sides of the paper (step S3). At this time, due to mechanical factors (such as tolerance of the paper position regulation mechanism), a positional deviation occurs between the image formed on one side of the paper and the image formed on the back side. Here, it is assumed that the image on one side of the sheet is formed as shown in FIG. 3C and the image on the back side of the sheet is formed as shown in FIG.
Note that steps S2 and S3 correspond to the preliminary forming process in the present invention.

  Subsequently, the CPU 10 adjusts the light amount of the light source provided in the document reading unit 15 to a light amount that causes a show-through phenomenon (step S4). Here, the show-through phenomenon refers to a phenomenon in which, when a single-sided image of a document is read, the back-side image of the document is reflected in the single-sided image. In the show-through phenomenon, there is a reflecting object (for example, a conveyance roller) that reflects the illumination light transmitted through the document on the back side of the document at the document reading position, and the reflected light from the reflecting object is reflected on the document. The incident occurs from the back side and is received by the photoelectric conversion element. That is, the show-through phenomenon is more likely to occur as the light amount of the light source increases.

  Subsequently, the CPU 10 controls the document reading unit 15 and the image data storage unit 16 to transport the same document as that read in step S2 to the document reading position again using the front / back reversing mechanism, so that one side of the document Image data obtained by reading the image is stored in the image data storage unit 16 (step S5). Since the show-through phenomenon occurs here, the one-sided image of the read original is an image as shown in FIG.

  Subsequently, the CPU 10 reads the image data on one side of the original read in step S5 from the image data storage unit 16, and performs predetermined image processing so that the image is reflected on the one-sided image by the one-sided image and the show-through phenomenon. The positional relationship with the back image is measured (step S6). Here, as shown in FIG. 3E, there is no positional deviation between the single-sided image and the back-side image of the document read using the show-through phenomenon, and in this step S6 there is no ideal positional deviation. The positional relationship between the single-sided image and the backside image in a typical situation is measured. In addition, in order to discriminate between the single-sided image and the backside image, an image processing method for discriminating a single-sided image having a density equal to or higher than a predetermined threshold can be adopted, and the positional relationship between the single-sided image and the backside image is measured. In this case, it is possible to employ an image processing method such as detecting edges of both images and measuring the distance between the edges of both images.

  Subsequently, the CPU 10 controls the document reading unit 15 and the image data storage unit 16 to read a single-sided image (same as the single-sided image of the original) of the paper on which the image is formed on both sides in step S3. Are stored in the image data storage unit 16 (step S7). Since the show-through phenomenon occurs here, the one-sided image of the read paper is an image as shown in FIG. In this step S7, when the paper on which the image is formed in step S3 is ejected to the paper ejection tray, a display for prompting the user to read the paper is displayed on the operation display unit 18, and the user removes the paper. It may be set on the document tray, or a mechanism for automatically transporting the paper after the image formation to the document reading position may be provided.

Subsequently, the CPU 10 reads the image data on one side of the paper read in step S7 from the image data storage unit 16, and performs the same image processing as in step S6, so that the image appears on the one side image due to the paper single side image and the show-through phenomenon. The positional relationship with the back side image is measured (step S8). Here, as shown in FIG. 3 (f), a positional deviation occurs between the single-sided image and the back-side image of the paper read using the show-through phenomenon. In this step S8, the positional deviation occurs. In this situation, the positional relationship between the single-sided image and the back-side image is measured.
Note that steps S4 to S8 correspond to the positional relationship measurement process in the present invention.

 Subsequently, the CPU 10 calculates the positional deviation correction amount of the double-sided image formed on the paper based on the measurement result of the positional relationship between the single-sided image and the backside image of the document and paper (step S9). That is, the positional relationship between the single-sided image and the back side image of the document measured in step S6 is a positional relationship in an ideal situation with no positional deviation, and the positional relationship between the single-sided image and the back side image of the paper measured in step S8. Since the relationship is a positional relationship in a situation where a positional deviation has occurred, the positional deviation amount of the images on both sides formed on the paper can be calculated by taking the difference between the two, and the positional deviation amount can be calculated from this positional deviation amount. A correction amount can be calculated.

 Subsequently, the CPU 10 performs position shift correction based on the position shift correction amount calculated in step S9 (step S10). Specifically, as this misalignment correction, a method of shifting image data of either a single-sided image or a backside image of the paper in accordance with the amount of misalignment correction, a method of adjusting the conveyance timing of the paper, or the like is adopted. Can do. Then, the CPU 10 controls the paper transport unit 14 to transport new paper from the paper tray to the image forming unit 17, and also reads the image data on both sides of the document read in step S2 from the image data storage unit 16 to form an image. The unit 17 is controlled to form images on both sides of the document on both sides of the paper (step S11).

  As described above, according to the image forming apparatus 100 according to the present embodiment, a specific symbol (for example, “#”) as in the past is used in order to obtain a positional deviation correction amount for images formed on both sides of a sheet. Since the positional deviation correction amount can be obtained using a document that is an actual reading object without printing on a sheet, it is possible to improve the usability of the user.

In addition, this invention is not limited to the said embodiment, The following modifications can be considered.
(1) The CPU 10 updates the next positional deviation correction amount based on the total correction amount calculation mode for calculating the positional deviation correction amount every time the original is read, and the positional deviation correction amount calculated when one original is read. A function of selectively switching between the correction amount holding modes held until the timing may be provided.
For example, in the total correction amount calculation mode, steps S1 to S11 of FIG. 2 are performed for each original, and in the correction amount holding mode, steps S1 to S11 of FIG. 2 are performed for one original. The positional deviation correction amount calculated in step S9 is held in a storage circuit such as a register or RAM, and the positional deviation correction of the original is performed based on the positional deviation correction amount held from the second original, Images on both sides of the document are formed on both sides of the paper.

  By providing such a total correction amount calculation mode and a correction amount holding mode, the total correction amount calculation mode is used when it is desired to accurately align both sides of a document one by one. If it is allowed and the copy time is desired to be shortened, the correction amount holding mode can be used, and the user-friendliness can be further improved. It should be noted that when a mode switching instruction is input by an operation of the operation display unit 18 by the user, the total correction amount calculation mode and the correction amount holding mode may be switched.

(2) In the above-described embodiment, the light amount of the light source provided in the document reading unit 15 is adjusted to the light amount that causes the show-through phenomenon, and then the single-sided image of the original is read and then the single-sided image of the paper is read. However, the order is not limited to this, and the single-sided image of the original may be read after first reading the single-sided image of the paper. That is, the order of steps S5 and S6 and steps S7 and S8 in FIG. 2 may be changed.

1 is a schematic configuration diagram of an image forming apparatus 100 according to an embodiment of the present invention. 3 is an operation flowchart of the image forming apparatus 100 according to an embodiment of the present disclosure. FIG. 6 is an operation explanatory diagram of the image forming apparatus 100 according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 10 ... CPU (Central Processing Unit), 11 ... ROM (Read Only Memory), 12 ... RAM (Random Access Memory), 13 ... Various sensor groups, 14 ... Paper conveyance part, 15 ... Image reading part , 16 ... Image data storage unit, 17 ... Image forming unit, 18 ... Operation display unit, 19 ... Communication I / F unit, 200 ... PC

Claims (4)

A document reading unit that has a single-sided and double-sided reading function of an original and generates image data of a read image, an image forming unit that forms an image on one side and both sides of a sheet based on the image data, the original reading unit, An image forming apparatus comprising: a control unit that integrally controls the image forming unit;
The controller is
Based on image data obtained by reading both sides of the document, a preliminary forming process for forming images on both sides of the document on both sides of the paper;
After adjusting the light amount of the light source provided in the document reading unit to a light amount that causes a show-through phenomenon, based on the image data obtained by reading one side of the same document, the one-side image of the document and the show-through phenomenon While measuring the positional relationship with the back side image reflected in the single-sided image by the single-sided image and the show-through phenomenon based on the image data obtained by reading one side of the paper after the preliminary forming process A positional relationship measurement process for measuring the positional relationship with the back image reflected in the image;
A correction amount calculation process for calculating a positional deviation correction amount of the double-sided image formed on the paper based on the measurement result of the positional relationship between the single-sided image and the back-side image of the original and paper;
An image forming apparatus.   The control unit performs the preliminary forming process, the positional relationship measurement process, and the correction amount calculation process each time a document is read to calculate a total correction amount calculation mode for calculating a positional deviation correction amount for each original, and one original The image forming apparatus according to claim 1, wherein the image forming apparatus selectively switches between a correction amount holding mode in which the positional deviation correction amount calculated when the image is read is held until the next position deviation correction amount update timing.   The control unit performs position shift correction for each document based on the position shift correction amount calculated for each document in the total number correction amount calculation mode, and creates new images on both sides of the document for each document. The image forming apparatus according to claim 2, wherein the image forming apparatus is re-formed on both sides of the sheet. The control unit, in the correction amount holding mode, corrects the positional deviation of the document based on the held positional deviation correction amount, and forms images on both sides of the document on both sides of the paper. 2. The image forming apparatus according to 2.

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