JP6504118B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Generally, an image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine includes an ADF (Auto Document Feeder), an image reading unit, and an image forming unit. The ADF conveys a plurality of documents contained in the document bundle one by one.

  When the image reading unit is a so-called single-sided reading type, the image reading unit sequentially reads only an image of one side of the plurality of documents while the plurality of documents are conveyed once by the ADF. Output original image data.

  The image forming apparatus may include the image reading unit of the single-sided reading type and the image forming unit capable of performing double-sided printing for forming an image on both sides of a sheet. In this case, it is known that the image forming apparatus executes double-sided copying of a bundle of originals (see, for example, Patent Document 1).

  In double-sided copy processing of the document bundle, the user turns the document bundle upside down and sets the document bundle in the image forming apparatus twice. Then, the image reading unit executes the image reading process twice on the front side and the back side of the plurality of originals. Furthermore, the image forming unit executes the double-sided printing process based on the image data of both sides of the plurality of originals obtained by the image reading process twice. The image data of both sides of the plurality of originals is temporarily stored in the data storage unit of the image forming apparatus until it is used for the duplex printing process.

Unexamined-Japanese-Patent No. 2000-299753

  By the way, in the double-sided copying process of the document bundle, there is a possibility that an erroneous operation may occur in which the user sets the document bundle in the same direction twice in the same direction. When such an erroneous operation is performed, the sheet is consumed wastefully.

  Therefore, when a plurality of image data obtained in the double-sided copy process of the document bundle includes data of an image read from the same page in the document bundle, the execution of the double-sided printing process by the image forming unit is restricted. It is conceivable. In this case, it is necessary to use the storage area of the data storage unit as a work area in the process of determining the approximation status of a plurality of image data.

  On the other hand, the image reading unit of the single-sided reading type is often employed in the relatively inexpensive image forming apparatus. In such an image forming apparatus, it is not preferable to adopt the data storage unit having a large capacity. Therefore, in the process of determining the approximation status of a plurality of image data, an overflow of the data storage unit may occur.

  An object of the present invention is to prevent overlapping output of an image of the same original in double-sided copy processing of a bundle of originals by a single-sided reading type image reading unit and an image forming unit capable of double-sided printing while avoiding overflow of the data storage unit. It is an object of the present invention to provide an image forming apparatus that is particularly effective.

  An image forming apparatus according to one aspect of the present invention includes an original conveyance unit, an image reading unit, a data storage unit, an order setting unit, a page formation unit, a remaining work size estimation unit, and an approximation condition setting unit. , An approximate page determination unit, an image forming unit, and a print restriction unit. The document transport unit can transport a plurality of documents included in a document bundle one by one. The image reading unit sequentially outputs a plurality of document page data, which is image data corresponding to a plurality of pages of the document bundle, while sequentially reading images of one side of the plurality of documents conveyed by the document conveyance unit. Image reading processing can be performed. The data storage unit can store data. The order setting unit sets an output page order which is an output order of images of a plurality of pages in the document bundle. The page organization unit uses the storage area of the data storage unit as a work area, and the plurality of original page data obtained by the two sequential image reading processes performed in a state in which the front and back sides of the original bundle are different. Certain double-sided original image data is organized into a plurality of continuous output page image data in the output page order. The remaining work size estimation unit depends on the free space of the data storage unit and the size of a work area used by the page organization unit in the data storage unit while the first sequential image reading process is performed. In parallel to the processing of the page formation unit in the data storage unit, the size of a remaining work region which is a usable work region is estimated. The approximation condition setting unit is an image approximation condition, which is a condition for determining whether or not the two original page data in the double-sided original image data is data of an image read from the same page in the original bundle. Set according to the estimation result of the remaining work size estimation unit. The approximate page determination unit determines whether the double-sided original image data includes two pieces of original page data satisfying the image approximation condition while using the storage area of the data storage unit as a work area. The image forming unit can perform duplex printing processing in which images corresponding to the plurality of output page image data obtained from the page organization unit are sequentially formed on both sides of a plurality of sheets. The print restriction unit executes the double-sided printing process by the image forming unit when the approximate page determination unit determines that the double-sided document image data includes two pieces of document page data that satisfy the image approximation condition. Limit. The approximation condition setting unit sets the image approximation condition in which a work area to be used is smaller than when the estimation result of the remaining work area by the remaining work size estimation unit is smaller than when the result is small.

  According to the present invention, the overlapping output of the image of the same original is prevented in the double-sided copy processing of the original bundle by the single-sided reading type image reading unit and the double-sided printable image forming unit while avoiding the overflow of the data storage unit. It becomes possible to provide an especially effective image forming apparatus.

FIG. 1 is a block diagram of an image forming apparatus according to the embodiment. FIG. 2 is a flowchart showing an example of the procedure of data accumulation control in the image forming apparatus according to the embodiment. FIG. 3 is a flowchart illustrating an example of the procedure of the overlap inspection process in the image forming apparatus according to the embodiment. FIG. 4 is a flowchart illustrating an example of the procedure of the page image output process in the image forming apparatus according to the embodiment. FIG. 5 is a view showing a procedure for setting a bundle of originals in the feed tray of the ADF in the front side pre-reading mode. FIG. 6 is a diagram showing a procedure for setting a bundle of originals in the feed tray of the ADF in the front side read mode. FIG. 7 is a diagram showing an example of the output page order in the front side prefetching mode. FIG. 8 is a diagram showing an example of the output page order in the back surface pre-read mode. FIG. 9 is a view schematically illustrating the printing order on a plurality of sheets in the duplex copying process of the image forming apparatus according to the embodiment. FIG. 10 is a view showing an example of comparison target areas of images in the overlapping inspection process of the image forming apparatus according to the embodiment. FIG. 11 is a diagram showing an example of the frequency distribution of the image density when the number of classes of the image density class is large. FIG. 12 is a diagram showing an example of the frequency distribution of the image density when the number of classifications of the image density class is small.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and does not have the property of limiting the technical scope of the present invention.

[Configuration of Image Forming Apparatus 10]
As shown in FIG. 1, the image forming apparatus 10 according to the embodiment includes an ADF 1, an image reading unit 2, an image forming unit 3, a built-in storage 4, a control unit 5, an operation display unit 6 and the like. The image forming apparatus 10 is, for example, a copying machine or a multifunction machine. The operation display unit 6 is a user interface including an operation unit and a display unit.

  The ADF 1 is a device that conveys a plurality of documents 91 included in the document bundle 910 placed on the supply tray 1A one by one from the supply tray 1A to the discharge tray 1B. The ADF 1 includes a document sensor 1C that detects whether the document 91 is placed on the supply tray 1A. The ADF 1 is an example of a document conveyance unit.

  The image reading unit 2 is a device that reads an image of a document 91. The image reading unit 2 can also output a document image data while sequentially reading an image on one side of a plurality of documents 91 conveyed by the ADF 1. Hereinafter, this process is referred to as sequential image reading process.

  The image reading unit 2 is a so-called single-sided reading type. Therefore, while the plurality of documents 91 are conveyed once by the ADF 1, the image reading unit 2 outputs the document image data while sequentially reading only the image on one side of the plurality of documents 91.

  The image reading unit 2 includes a light source for emitting light to the document 91, a line sensor for receiving the reflected light from the document 91, and outputting the document image data.

  The image forming unit 3 is an apparatus that executes an image forming process for forming an image on the sheet 92 by a predetermined method such as an electrophotographic method or an inkjet method. In the present embodiment, the image forming unit 3 can perform double-sided printing processing.

  The double-sided printing process is a process of sequentially forming images corresponding to a plurality of output page image data D2 on both sides of a plurality of sheets 92. The image forming unit 3 includes a turnback mechanism that reverses the direction of the sheet 92 during conveyance when the double-sided printing process is performed.

  As shown in FIG. 9, the image forming unit 3 forms an image on both sides of the plurality of sheets 92 in accordance with the order of the plurality of pages in the document bundle 910. FIG. 9 shows the order of printing on a plurality of sheets 92 in the double-sided copying process, taking the case where the number of originals N of the original bundle 910 is three as an example. In FIGS. 5, 6, and 9, G1 to G6 are symbols representing the images from the first page to the sixth page in the document bundle 910.

  The printing order shown in FIG. 9 is as follows. First, the image of the first page of the bundle of original documents 910 is formed on the front surface 92X of the first sheet 92, and then the image of the second page of the bundle of original documents 910 is on the back surface 92Y of the first sheet 92. It is formed. Next, the image of the third page of the document bundle 910 is formed on the front surface 92X of the second sheet 92, and then the image of the fourth page of the document bundle 910 is the back surface 92Y of the second sheet 92. Is formed. Further, the image of the fifth page of the bundle of documents 910 is formed on the front surface 92X of the third sheet 92, and finally, the image of the sixth page of the bundle of documents 910 is on the back surface 92Y of the third sheet 92. It is formed.

  The plurality of pieces of output page image data D 2 are supplied from the image processing unit 54 of the control unit 5 to the image forming unit 3. For example, when the image forming apparatus 10 executes the double-sided copying process, the ADF 1 and the image reading unit 2 sequentially execute the image reading process twice in a state in which the front and back of the document bundle 910 are different. Thereby, double-sided original image data D1 which is the original image data of both sides of a plurality of originals 91 is obtained.

  Furthermore, in the double-sided copying process, the image processing unit 54 organizes a plurality of output page image data D2 based on the double-sided original image data D1, and the image forming unit 3 performs the double-sided printing based on the plurality of output page image data D2. Execute the process An output page order Dx0, which is an output order of images of a plurality of pages in the document bundle 910, is preset by the image processing unit 54.

  That is, the image processing unit 54 sets a plurality of continuous double-sided original image data D1 obtained by the two sequential image reading processes performed in a state where the front and back of the original bundle 910 are different, in a preset output page order Dx0. Organize into output page image data D2.

  In the present embodiment, the double-sided copying process is executed in the front side prefetching mode. As shown in FIG. 5, in the front side pre-reading mode, the document bundle 910 is set on the supply tray 1A so that the front side 91X of the plurality of originals 91 is read in the first sequential image reading process. The document bundle 910 is set on the supply tray 1A so that the back side 91Y of the plurality of documents 91 can be read in the sequential image reading process.

  For example, it is assumed that the front side reading mode is adopted and the number N of originals of the original bundle 910 is three. In this case, as shown in FIG. 7, when the output page order Dx0 is represented by a series of numbers arranged in the order of the read numbers D0 (= 1 to 6) of six pages in the document bundle 910, the output page order Dx0 is (1 , 3, 5, 6, 4, 2).

  That is, in the front side prefetching mode, the numerical sequence of the output page order Dx0 corresponding to the read number D0 is represented by the numbers of the odd pages arranged in ascending order and the numbers of the even pages arranged in descending order.

  In the front side pre-reading mode, only the first reading number D0 of the output page order Dx0 is decided before the number of originals N is decided. Furthermore, another odd-numbered read number D0 in the output page order Dx0 is determined each time an image of one page of the document 91 is read in the first sequential image reading process. Further, all the even-numbered read numbers D0 in the output page order Dx0 are determined when the number N of originals is determined. The number N of originals is determined when at least the first sequential image reading process is completed.

  A back surface pre-read mode can be considered as the operation mode different from the front surface pre-read mode. As shown in FIG. 6, in the back surface pre-reading mode, the document bundle 910 is set on the supply tray 1A so that the back surface 91Y of a plurality of documents 91 can be read in the first sequential image reading process. The document bundle 910 is set on the supply tray 1A so that the front side 91X of the plurality of documents 91 can be read in the sequential image reading process.

  When the back surface pre-read mode is adopted, as shown in FIG. 8, the number sequence of the output page order Dx0 corresponding to the read number D0 is the even page number arranged in descending order and the odd page arranged subsequently in ascending order. It is represented by the number of. In the back surface pre-reading mode, all of the output page order Dx0 is determined only after the number N of originals is determined.

  However, in both the front side read mode and the front side read mode, part of the double-sided original image data D1 output from the image reading unit 2 next is data of an odd page in the original bundle 910 or is even It is possible to determine if it is page data.

  For example, information on the output page order Dx0 is stored in a volatile storage unit such as a random access memory (RAM).

  The internal storage 4 is a computer readable non-volatile memory. The built-in storage 4 can store various data such as double-sided original image data D1. For example, a hard disk drive or a solid state drive (SSD) is adopted as the built-in storage 4. The built-in storage 4 is an example of a data storage unit included in the image forming apparatus 10.

  The internal storage 4 is temporarily used as a save destination of the double-sided original image data D1 in the double-sided copying process. The internal storage 4 is returned to the state before use by the end of the double-sided copying process.

  The control unit 5 executes various calculations, data processing, and control of various electronic devices included in the image forming apparatus 10. The control unit 5 can exchange data and control signals with the built-in storage 4 through the bus.

  The control unit 5 includes an ADF control unit 51 that controls the ADF 1, an image reading control unit 52 that controls the image reading unit 2, a print control unit 53 that controls the image forming unit 3, an image processing unit 54, and operation display. And a UI (User Interface) control unit 55 that controls the unit 6.

  For example, the control unit 5 is realized by a processor that executes a program stored in advance in the internal storage 4 or the like.

  By the way, in the double-sided copying process of the document bundle 910, there is a possibility that an erroneous operation may occur in which the user sets the document bundle 910 twice on the supply tray 1A of the ADF 1 in the same direction. When such an erroneous operation is performed, the sheet 92 is wastefully consumed.

  In the following description, data of one page in double-sided original image data D1 is referred to as original page data D10. That is, the double-sided document image data D1 is a plurality of document page data D10 obtained by the two sequential image reading processes performed in a state where the front and back of the document bundle 910 are different.

  Therefore, when the plurality of document page data D10 obtained in the double-sided copy process of the document bundle 910 includes data of an image read from the same page in the document bundle 910, execution of the double-sided printing process by the image forming unit 3 It is conceivable to limit the In this case, it is necessary to use the storage area of the built-in storage 4 as a work area in the process of determining the approximation situation of the plurality of original page data D10.

  On the other hand, the single-sided reading type image reading unit 2 is often employed in a relatively inexpensive image forming apparatus 10. In such an image forming apparatus 10, it is not preferable to adopt the built-in storage 4 having a large capacity. Therefore, in the process of determining the approximation state of the plurality of original page data D10, an overflow of the internal storage 4 may occur.

  However, when the double-sided copying process is performed, the image processing unit 54 of the image forming apparatus 10 executes data accumulation control, duplicate inspection process, and page image output process described later. Thereby, the image forming apparatus 10 performs the same process in the double-sided copying process of the document bundle 910 by the single-sided reading type image reading unit 2 and the double-sided printable image forming unit 3 while avoiding the overflow of the built-in storage 4. The apparatus is effective in preventing the duplicate output of the image of the original 91.

[Image processing unit 54]
The image processing unit 54 includes an order setting unit 540, a data storage control unit 541 that mainly performs the data storage control, a duplication inspection unit 542 that performs the duplication inspection processing, and a page that mainly performs the page image output processing. And an image output unit 543.

  The overlap inspection unit 542 includes a remaining work size estimation unit 542A, an approximation condition setting unit 542B, an approximation page determination unit 542C, a print restriction unit 542D, and the like.

  In the data storage control, the data storage control unit 541 temporarily stores double-sided original image data D1 in the built-in storage 4. That is, the data storage control unit 541 uses the storage area of the internal storage 4 as a work area for temporarily storing double-sided original image data D1.

  Further, in the overlap inspection process, the overlap inspection unit 542 determines whether or not the double-sided reading including the data of the image in which the double-sided original image data D1 is read from the same page in the original bundle 910 has occurred. Furthermore, when it is determined that the duplicate reading has occurred, the duplication inspection unit 542 restricts the execution of the double-sided printing process by the image forming unit 3.

  On the other hand, page image output unit 543 sequentially acquires a plurality of document page data D10 in double-sided document image data D1 from built-in storage 4 in accordance with output page order Dx0, and sequentially outputs output page image data D2 corresponding to the acquired data. . This process is the page image output process. The output page image data D2 is output to the image forming unit 3 through the print control unit 53.

  Data accumulation control unit 541 and page image output unit 543 organize double-sided original image data D1 into a plurality of continuous output page image data D2 in output page order Dx0 while using the storage area of internal storage 4 as a work area. . The data storage control unit 541 and the page image output unit 543 are an example of a page formation unit.

[Said data storage control]
Hereinafter, an example of the procedure of the data storage control will be described with reference to the flowchart shown in FIG. In the following description, S101, S102,... Represent identification codes of steps performed in the data storage control.

  The data storage control unit 541 detects that the start operation of the double-sided copying process is performed on the operation display unit 6 while the document sensor 1C detects the document 91, the data storage control To start. When the document sensor 1C detects the document 91, the document 91 is placed on the supply tray 1A of the ADF 1.

<Step S101>
In the data storage control, the data storage control unit 541 initializes the reading number i. The reading number i is a numerical value which is counted up each time an image of one page of the document 91 is read in the sequential image reading process. The reading number i represents the order in which each of the plurality of document page data D10 is obtained in the two sequential image reading processes.

<Step S102>
Next, the image reading control unit 52 causes the image reading unit 2 to execute the image reading process for the i-th one page. As a result, the i-th document page data D10 is output from the image reading unit 2 to the image processing unit 54.

<Step S103>
Next, the data storage control unit 541 causes the internal storage 4 to temporarily store the i-th document page data D10. The data storage control unit 541 continues the process of step S103 until the recording of all the i-th document page data D10 in the internal storage 4 is completed.

  While the data storage control unit 541 is recording the i-th document page data D10 in the built-in storage 4, the size of the document page data D10 may exceed the empty capacity of the built-in storage 4. In this case, the data storage control unit 541 interrupts the data storage control and outputs an error notification through the operation display unit 6.

<Step S104>
Next, the duplication inspection unit 542 executes the duplication inspection process. A specific example of the duplicate inspection process will be described later.

<Step S105>
Further, the data storage control unit 541 determines whether or not the next document 91 is not present in the supply tray 1A according to the detection result of the document sensor 1C.

  Then, if it is determined that the next original 91 exists in the supply tray 1A, the data storage control unit 541 shifts the process to step S114. As described later, after the reading number i is counted up in step S114, the process from step S102 is repeated.

  On the other hand, when the data storage control unit 541 determines that the next document 91 does not exist in the supply tray 1A, the process proceeds to step S106.

<Step S106>
In step S106, the data storage control unit 541 determines whether or not the first sequential image reading process has been completed. If the data accumulation control unit 541 determines that the first sequential image reading process has been completed, the data accumulation control unit 541 shifts the process to step S107.

  On the other hand, when the data storage control unit 541 determines that the second sequential image reading process has been completed, the data storage control unit 541 ends the data storage control.

<Step S107>
In step S107, the data storage control unit 541 sets the read number i at that time as the number N of documents. That is, when the first sequential image reading process is completed, the number N of originals is determined. The doubled number of originals N is the total number of pages of the original bundle 910.

<Step S108>
Further, the order setting unit 540 sets the output page order Dx0 based on the number N of originals. That is, when the first sequential image reading process in the front side pre-reading mode is finished, the order setting unit 540 sets all of the output page order Dx0 based on the number N of originals.

<Step S109>
Furthermore, the remaining work size estimation unit 542A of the duplication inspection unit 542 checks the free capacity of the built-in storage 4.

<Step S110>
Furthermore, the remaining work size estimation unit 542A estimates the size of the remaining work area in the built-in storage 4. The remaining work area is a work area that can be used in parallel with the processing of the data storage control unit 541 and the page image output unit 543.

  The remaining work size estimation unit 542A determines the size of the work area used by the data storage control unit 541 in the internal storage 4 while the empty capacity of the internal storage 4 checked in step S109 and the first sequential image reading process are performed. Depending on the size, the size of the remaining work area is estimated.

  In the following description, the size of the work area used by the data storage control unit 541 in the built-in storage 4 while the first sequential image reading process is performed will be referred to as the organization work size. Usually, the organization work size is equal to the total size of a plurality of original page data D10 obtained by the first sequential image reading process.

  For example, the remaining work size estimation unit 542A subtracts the data capacity obtained by multiplying the size twice as large as the organization work size by a predetermined margin factor or more from the empty capacity of the internal storage 4 The capacity obtained by subtraction is calculated as the size of the remaining work area. Generally, the larger the number N of originals, the smaller the remaining work area.

<Step S111>
Next, the approximation condition setting unit 542B of the duplication inspection unit 542 sets the image approximation condition Dx1 according to the estimation result of the size of the remaining work area.

  The image approximation condition Dx1 is a condition for determining whether or not the two document page data D10 in the double-sided document image data D1 is data of an image read from the same page in the document bundle 910.

  The image approximation condition Dx1 sets the image approximation condition Dx1 in which the work area to be used is smaller than in the case where the estimation result of the remaining work area by the remaining work size estimation unit 542A is small. However, when the image approximation condition Dx1 in which the work area to be used is small is adopted, the accuracy in detecting that the image of the same page is read is not high.

  For example, it is conceivable that the image approximation condition Dx1 includes the conditions of the comparison image regions g1 and g2 selected from a plurality of candidates (see FIG. 10). The comparison image areas g1 and g2 are image areas to be compared in the two original page data D10. The comparison image areas g1 and g2 illustrated in FIG. 10 are parts of the entire image area g0 corresponding to the size of the document 91.

  The approximation condition setting unit 542B sets an image approximation condition Dx1 in which the sizes of the comparison image areas g1 and g2 differ according to the estimation result of the size of the remaining work area. More specifically, the approximation condition setting unit 542B sets an image approximation condition Dx1 in which the comparative image areas g1 and g2 are narrower when the estimation result of the size of the remaining work area is smaller than when the estimation result of the size of the remaining work area is large.

  When the image approximation condition Dx1 in which the comparison image areas g1 and g2 are narrow is adopted, the built-in necessary for the process of determining the image approximation condition Dx1 than in the case where the image approximation condition Dx1 is wide Work area of storage 4 is small.

  In the example shown in FIG. 10, the comparison image areas g1 and g2 under the image approximation condition Dx1 include the first comparison image area g1 and the second comparison image area g2.

  The first comparison image area g1 is an area common to the document page data D10 obtained by the first sequential image reading process and the document page data D10 obtained by the second sequential image reading process.

  On the other hand, the second comparison image area g2 is an area applied only to document page data D10 obtained by the second sequential image reading process. The second comparison image area g2 is an area that is point-symmetrical to the first comparison image area g1 based on the center g00 of the entire image area g0.

  The following two can be considered as erroneous operations when the original bundle 910 is placed on the supply tray 1A in the two sequential image reading processes. The first erroneous operation is an operation of placing the document bundle 910 on the supply tray 1A in exactly the same direction in the first and second operations. The second erroneous operation is an operation of placing the document bundle 910 on the supply tray 1A in a state in which the front and back direction is the same for the first time and the second time and the front and back direction is opposite.

  By setting two comparison image areas g1 and g2, it is possible to cope with both the first erroneous operation and the second erroneous operation.

  Further, it is considered that the image approximation condition Dx1 includes the condition of the frequency distribution of the feature amount of the image to be compared with respect to the two original page data D10 (see FIGS. 11 and 12). The feature amount is, for example, an image density or a hue for each unit area. FIGS. 11 and 12 show an example of the frequency distribution when the feature amount is the image density.

  In the two original document page data D10 to be compared, the image approximation condition Dx1 is satisfied when the difference in the frequency of each class in the frequency distribution of the feature amount is within the predetermined allowable range.

  Then, the approximation condition setting unit 542B sets the image approximation condition Dx1 in which the number of classes of the feature of the feature distribution in the frequency distribution of the feature is different according to the estimation result of the size of the remaining work area.

  More specifically, the approximation condition setting unit 542 B generates the condition of the frequency distribution in which the number of divisions of the class of the feature amount is smaller when the estimation result of the size of the remaining work area is smaller than when the estimation result is large. The approximation condition Dx1 is set. FIG. 11 shows an example of the frequency distribution when the number of classes of the image density is large, and FIG. 12 shows an example of the frequency distribution when the number of classes of the image density is small.

  When the image approximation condition Dx1 in which the number of classifications of the class of the feature amount is small is adopted, it is necessary in the process of determining the image approximation condition Dx1 than in the case where the image approximation condition Dx1 with many comparative image areas g1 and g2 The work area of internal storage 4 is small.

  Further, when each of the document page data D10 is color image data including three primary color image data, the approximate condition setting unit 542B calculates the next primary color image approximate condition and the combined image according to the estimation result of the remaining work area. It is conceivable to set one of the approximation conditions as the image approximation condition Dx1.

  The primary color image approximation condition is an approximation condition in which two original page data D10 are compared for each of the three primary color image data. The integrated image approximation condition is an approximation condition in which two original page data D10 are compared by an integrated value of the three primary color image data. The integrated value is an average value of the three primary color image data.

  When the integrated image approximation condition is adopted, the work area of the built-in storage 4 required in the process of determining the image approximation condition Dx1 is smaller than when the primary color image approximation condition is adopted.

  The approximation condition setting unit 542B sets the integrated image approximation condition as the image approximation condition Dx1 when the estimation result of the remaining work area is smaller than a predetermined first reference value, and in the other cases, the primary color The image approximation condition is set as an image approximation condition Dx1.

  In addition, a character distribution condition in which the approximate condition setting unit 542 B compares the distribution of the extraction number for each of the plurality of characters extracted from the two original page data D 10 by character recognition processing is set as the image approximate condition Dx 1 Is also conceivable.

  For example, the approximation condition setting unit 542B does not set the character distribution condition as the image approximation condition Dx1 when the estimation result of the remaining work area is smaller than a predetermined second reference value, and in other cases. The character distribution condition is set as part of the image approximation condition Dx1.

  When the character distribution condition is not adopted, the work area of the built-in storage 4 required in the process of determining the image approximation condition Dx1 is smaller than when the character distribution condition is adopted as a part of the image approximation condition Dx1.

<Step S112>
Next, the approximate page determination unit 542C detects the feature amounts of the first to Nth document page data D10 obtained in the first sequential image reading process, and stores the detection result in the internal storage 4 . At this time, the approximate page determination unit 542C executes the process of detecting the feature while using the storage area of the internal storage 4 as a work area.

  When the condition of the comparison image area g1 is included in the image approximation condition Dx1, the approximate page determination unit 542C detects the feature amount of the image data in the comparison image area g1. Further, when the image approximation condition Dx1 includes the condition of the number of class divisions in the frequency distribution of the feature amount, the approximate page determination unit 542C derives the frequency distribution of the feature amount according to the condition of the number of class divisions.

  When the primary color image approximation condition is set in the image approximation condition Dx1, the approximate page determination unit 542C detects the feature amount for each of the three primary color image data. On the other hand, when the integrated image approximation condition is set in the image approximation condition Dx1, the approximate page determination unit 542C detects the feature amount using the integrated value of the three primary color image data.

  Further, when the character distribution condition is set as a part of the image approximation condition Dx1, the approximate page determination unit 542C extracts a plurality of characters from the document page data D10 by the character recognition processing, and the number of extractions for each character Count. Then, the approximate page determination unit 542C stores the information of the distribution of the extraction number for each character in the internal storage 4 as one of the feature amounts.

  When the condition of the comparison image area g1 is included in the image approximation condition Dx1, the approximate page determination unit 542C performs the character recognition process on the image data in the comparison image area g1.

  Then, the approximate page determination unit 542C shifts the process from step S112 to step S113.

<Step S113>
Furthermore, the data storage control unit 541 stands by until the document sensor 1C detects the document 91, that is, until the document bundle 910 whose front and back is reversed is placed on the supply tray 1A. Then, when the document bundle 910 is placed on the supply tray 1A, the data storage control unit 541 shifts the process to step S102.

<Step S114>
In step S114, the data storage control unit 541 counts up the read number i as described above. Thereafter, the data storage control unit 541 shifts the process to step S102. As a result, the second sequential image reading process starts. Further, the other half of the double-sided original image data D1 output from the image reading unit 2 is recorded in the built-in storage 4 (S103).

[The duplicate check process]
Hereinafter, an example of the procedure of the duplicate inspection process executed in step S104 of FIG. 2 will be described with reference to the flowchart shown in FIG. In the following description, S201, S202,... Represent identification codes of steps performed in the duplicate inspection process.

<Step S201>
In the overlapping inspection process, first, the approximate page determination unit 542C determines whether the second sequential image reading process is being performed. If the approximate page determination unit 542C determines that the first sequential image reading process is being performed, the approximate page determination unit 542C ends the overlapping inspection process.

  On the other hand, if the approximate page determination unit 542C determines that the second sequential image reading process is being performed, the approximate page determination unit 542 shifts the process to the next step S202.

<Step S202>
In step S202, the approximate page determination unit 542C detects the feature of the i-th document page data D10, and stores the detection result in the internal storage 4. At this time, the approximate page determination unit 542C executes the process of detecting the feature while using the storage area of the internal storage 4 as a work area.

  In step S202, the approximate page determination unit 542C derives the frequency distribution of the feature amount such as the image density for the i-th document page data D10 as in the process of step S112. Furthermore, as necessary, the approximate page determination unit 542C extracts a plurality of characters by the character recognition process for the i-th document page data D10, and information of the extraction number for each character is 1 of the distribution information of the feature amount. Derive as one.

<Step S203>
Furthermore, the approximate page determination unit 542C detects the feature amount of the i-th document page data D10 and the detection result of the feature amount of any of the first to N-th document page data D10. It is determined whether the approximation condition Dx1 is satisfied.

  That is, in step S203, whether or not the approximate page determination unit 542C uses the storage area of the internal storage 4 as a work area, and the two-sided original image data D1 includes two original page data D10 satisfying the image approximation condition Dx1. Determine

  If the approximate page determination unit 542C determines that the ith original page data D10 does not satisfy the image approximation condition Dx1 between the first to Nth original page data D10, the process proceeds to step S204.

  On the other hand, if the approximate page determination unit 542C determines that the ith document page data D10 satisfies the image approximation condition Dx1 with any of the first to Nth document page data D10, the process proceeds to step S205. Migrate.

<Step S204>
In step S204, the approximate page determination unit 542C deletes the detection result of the feature amount of the i-th document page data D10 from the built-in storage 4. Thus, the duplicate inspection process on the i-th document page data D10 is completed.

<Step S205>
In step S205, the approximate page determination unit 542C outputs an error notification through the UI control unit 55 and the operation display unit 6.

<Step S206>
Furthermore, the approximate page determination unit 542C sets the output prohibition flag to ON. Thus, the duplicate inspection process on the i-th document page data D10 is completed.

  The output prohibition flag is a flag for identifying whether or not the execution of the double-sided printing process by the image forming unit 3 should be prohibited. As described later, when the output prohibition flag is ON, the print restriction unit 542D of the duplication inspection unit 542 restricts the execution of the double-sided printing process. The initial value of the output prohibition flag is OFF.

[Page image output process]
Hereinafter, an example of the procedure of the page image output process will be described with reference to the flowchart shown in FIG. In the following description, S301, S302,... Indicate identification codes of steps performed in the page image output process. The page image output process is performed in parallel with the data storage control.

<Step S301>
First, the page image output unit 543 initializes the output number j. The output number j is a numerical value which is counted up each time the output page image data D2 corresponding to the document page data D10 is output in accordance with the output page order Dx0. The output number j represents the order in which the page image output unit 543 organizes and outputs each of the plurality of output page image data D2 from the duplex original image data D1.

<Step S302>
Next, the print restriction unit 542D of the duplication inspection unit 542 changes the transfer destination of the next process according to whether or not the output prohibition flag is OFF. If the output prohibition flag is OFF, the print restriction unit 542D shifts the process to step S303. On the other hand, when the output prohibition flag is ON, the print restriction unit 542D shifts the process to step S308.

<Step S303>
In step S303, the page image output unit 543 monitors whether or not the original page data D10 corresponding to the j-th page of the output page order Dx0 is recorded in the internal storage 4.

  When the page image output unit 543 confirms that the original page data D10 corresponding to the j-th page of the output page order Dx0 exists in the internal storage 4, the process proceeds to the next step S304. Otherwise, the processes of steps S302 and S303 are repeated.

<Step S304>
In step S304, the page image output unit 543 acquires document page data D10 corresponding to the j-th page of the output page order Dx0 from the internal storage 4.

  In step S304, the page image output unit 543 erases the acquired document page data D10 from the built-in storage 4.

<Step S305>
Furthermore, the page image output unit 543 converts the original page data D10 corresponding to the j-th page of the acquired output page order Dx0 into the output page image data D2 for image formation, and the output page image data D2 is printed. The image is output to the image forming unit 3 through the control unit 53.

  The print control unit 53 causes the image forming unit 3 to execute double-sided printing processing based on a plurality of output page image data D2 sequentially output from the page image output unit 543.

<Step S306>
Next, the page image output unit 543 determines whether the output number j has reached twice the number N of originals. If the page image output unit 543 determines that the output number j has not reached twice the number of documents N, the page image output unit 543 shifts the process to step S307. On the other hand, when the page image output unit 543 determines that the output number j has reached twice the number N of originals, the page image output processing is ended.

<Step S307>
In step S307, the page image output unit 543 counts up the output number j, and then shifts the process to step S302. Thus, the process from step S302 is repeated until the output number j reaches twice the number N of originals.

<Step S308>
In step S308, the print restriction unit 542D determines whether a predetermined prohibition release operation has been performed on the operation display unit 6. The prohibition cancellation operation is an operation in which the user confirms the error notification output in step S205, and then cancels the restriction on the duplex printing process according to the user's intention.

  If the prohibition release operation is not performed on the operation display unit 6, the print restriction unit 542D shifts the process to step S302. Therefore, when the approximate page determination unit 542C determines that the double-sided original image data D1 includes the two original page data D10 satisfying the image approximation condition Dx1, the both-side printing process is performed unless the user performs the prohibition release operation. Will not take place.

<Step S309>
On the other hand, when the prohibition release operation is performed on the operation display unit 6, the print restriction unit 542D shifts the process to step S304 after setting the output prohibition flag to OFF. As a result, the document page data D10 is output to the image forming unit 3 through the print control unit 53 (S305), and the double-sided printing process is performed.

  As described above, when the approximate page determination unit 542C determines that the double-sided original image data D1 includes the two original page data D10 that satisfy the image approximation condition Dx1 (S203), the print restriction unit 542D The execution of the double-sided printing process by the forming unit 3 is restricted (S206, S302, S308).

  If the image forming apparatus 10 is adopted, the same double-sided copying process of the document bundle 910 by the single-sided reading type image reading unit 2 and the double-sided printable image forming unit 3 is performed while avoiding the overflow of the built-in storage 4. Duplicate output of the image of the original 91 can be prevented.

[Application example]
In the image forming apparatus 10, an application as shown below may be adopted as the process of the approximate page determination unit 542C. In the application example, the approximate page determination unit 542C determines, based on the estimation result of the remaining work area by the remaining work size estimation unit 542A, document page data D10 to be subjected to the determination of the image approximation condition Dx1 in double-sided document image data D1. Change the number of

  For example, when the estimation result of the remaining work area is smaller than a predetermined lower limit value, the approximate page determination unit 542C determines that the document for a very small number of pages is processed in steps S112 of FIG. It is conceivable to determine the image approximation condition Dx1 only for the page data D10.

  More specifically, it is conceivable that the approximate page determination unit 542C determines the image approximation condition Dx1 only for the first and (N + 1) th document page data D10. As the user's erroneous operation regarding the setting of the document bundle 910, the first erroneous operation or the second erroneous operation is common. In this case, there is a high possibility that the image approximation condition Dx1 is satisfied for the first page original 91 in each of the first and second sequential image reading processes.

  According to the application example, the work area of the built-in storage 4 required in the process of determining the image approximation condition Dx1 can be made smaller as needed.

  Note that the image forming apparatus according to the present invention freely combines the above-described embodiment and application examples within the scope of the invention described in each claim, or suitably modifies the embodiment and application examples. Or it is also possible to comprise by abbreviate | omitting a part.

1: ADF (original conveyance unit)
1A: supply tray 1B: discharge tray 1C: document sensor 2: image reading unit 3: image forming unit 4: built-in storage (data storage unit)
5: control unit 6: operation display unit 10: image forming apparatus 51: ADF control unit 52: image reading control unit 53: print control unit 54: image processing unit 55: UI control unit 91: document 91X: document front surface 91Y The back side 92 of the document: the sheet 92X: the front side 92Y of the sheet: the back side 540 of the sheet: the order setting unit 541: the data storage control unit (page organization unit)
542: duplicate inspection unit 542A: remaining work size estimation unit 542B: approximation condition setting unit 542C: approximation page determination unit 542D: print restriction unit 543: page image output unit (page formation unit)
910: original bundle D0: reading number D1: double-sided original image data D10: original page data D2: output page image data Dx0: output page order Dx1: image approximation condition g0: all image area g00: center of all image area g1: first 1 comparison image area g2: second comparison image area

Claims (5)

A document transport unit capable of transporting a plurality of documents contained in a document bundle one by one;
It is possible to execute a sequential image reading process which sequentially outputs a plurality of document page data which is image data corresponding to a plurality of pages of the document bundle while sequentially reading an image of one side of the plurality of documents conveyed by the document conveyance unit Image reader and
A data storage unit capable of storing data;
An order setting unit configured to set an output page order which is an output order of images of a plurality of pages in the document bundle;
The double-sided document image data, which is the plurality of document page data obtained by the two sequential image reading processes performed with the front and back sides of the document bundle being different, using the storage area of the data storage unit as a work area A page organizing unit for organizing a plurality of continuous output page image data in the output page order;
The page organization in the data storage unit according to the free space of the data storage unit and the size of a work area used by the page organization unit in the data storage unit while the first sequential image reading process is performed. A remaining work size estimation unit for estimating the size of a remaining work area which is a work area that can be used in parallel with the processing of the part;
The remaining work size estimation unit estimates an image approximation condition which is a condition for determining whether or not the two original page data in the double-sided original image data are data of an image read from the same page in the original bundle. An approximation condition setting unit which is set according to the result,
An approximate page determination unit that determines whether the double-sided original image data includes two pieces of the original page data that satisfy the image approximation condition while using a storage area of the data storage unit as a work area;
An image forming unit capable of performing double-sided printing processing in which images corresponding to the plurality of output page image data obtained from the page formation unit are sequentially formed on both sides of a plurality of sheets;
A print restriction unit that restricts execution of the double-sided printing process by the image forming unit when the approximate page determination unit determines that the double-sided document image data includes two pieces of document page data that satisfy the image approximation condition; And
The image forming apparatus, wherein the approximation condition setting unit sets the image approximation condition in which a work area to be used is smaller than in the case where the estimation result of the remaining work area by the remaining work size estimation unit is smaller.   The approximation condition setting unit sets the image approximation condition in which the sizes of image regions to be compared in two pieces of the original document page data differ according to the estimation result of the remaining work region by the remaining work size estimation unit. An image forming apparatus according to claim 1.   The approximation condition setting unit is configured to count the number of classes of the feature amount in the feature distribution of the image to be compared for the two original document page data according to the remaining work area estimation result by the remaining work size estimation unit. The image forming apparatus according to claim 1, wherein the image approximation condition is set to be different.   When each of the plurality of document page data is color image data including primary color image data of three colors, the approximation condition setting unit determines whether the remaining work size estimation unit estimates the remaining work area by 2 or more. One of the image approximation condition of comparing two pieces of original page data for each of the three primary color image data and the image approximation condition of comparing two pieces of original page data by an integrated value of the three primary color image data The image forming apparatus according to any one of claims 1 to 3, wherein   The approximate page determination unit changes the number of the document page data to be subjected to the determination of the image approximation condition in the double-sided document image data according to the estimation result of the remaining work area by the remaining work size estimation unit. The image forming apparatus according to any one of claims 1 to 4.

Images