Image forming apparatus, control method, and program

Abstract

To provide an image forming apparatus, a control method, and a program that can classify a printing result for every original document when skimming through a bundle of single-sided documents and a bundle of double-sided documents before performing double-sided printing.SOLUTION: In executing blank removal+"double-sided→double-sided" copy execution processing while a single-sided / double-sided document mixed mode is turned on, when only one of the front face and the back face of an attention sheet separated and conveyed from a document bundle on a document tray is a blank surface, and when the total amount of print target pages from a head sheet of the document bundle to a sheet immediately before the attention sheet is an even number, an image forming apparatus 101 suspends blank paper skip determination for the attention sheet until the appearance of a subsequent second document sheet at least one of the front face and the back face of which is not a blank surface, when the front face and the back face of the second document sheet are both a non-blank surface, does not skip a blank surface of a first document sheet, and when only one of the front face and the back face of the second document sheet is a blank surface, skips the blank surface of the first document sheet.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, a control method, and a program, and more particularly to an image forming apparatus, a control method, and a program that read and print image data on a plurality of document sheets including blank pages. [Background technology]

[0002] Reading devices in image forming devices such as digital copiers mainly use two types of reading methods to read images on documents. One is a method in which the document position is fixed by placing the document on a platen glass, and the image on the document is read by moving the optical system (moving optical system method). The other is a method in which the position of the optical system is fixed, and the image on the document is read while being transported by an automatic document feeder (ADF) (skimming reading method).

[0003] Conventionally, in an image forming apparatus equipped with an ADF, when a document is mixed with documents printed on one side and documents printed on both sides, it is necessary to read both sides of the document printed on only one side. However, this method also reads the image on the back side (blank side) of the document printed on only one side, which results in processing unnecessary data. In addition, when printing the scanned image data, the blank side is also printed, which results in unnecessary paper consumption and power consumption. Therefore, various methods have been devised that determine whether the scanned image data is blank or not, and delete image data determined to be blank to suppress unnecessary printing and consumption of paper and toner.

[0004] As an example, Patent Document 1 proposes a blank page removal function that inputs a luminance signal obtained when reading a document to a blank page determination circuit and controls subsequent printing processing according to the determination result of the blank page determination circuit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-264363 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the blank page removal function of Patent Document 1, blank pages are uniformly removed from the print process. For this reason, for example, if a user uses the ADF to skim through both sides of a stack of single-sided documents and a stack of double-sided documents with an odd number of pages, and then uses the blank page removal function to perform double-sided printing, the last page of the single-sided document and the first page of the double-sided document are printed on the front and back of the same sheet, respectively. This print result is unintended for users who want to sort the documents by their original documents.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus, a control method, and a program that can sort the printed results by the original documents when scanning both sides of a stack of single-sided documents and a stack of double-sided documents and then printing on both sides. [Means for solving the problem]

[0008] In order to solve the above problem, an image forming apparatus according to claim 1 of the present invention includes an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a printing unit capable of double-sided printing, and a printer that detects whether the first side is a blank or non-blank side and detects whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit. and a blank page detection unit that detects whether or not the blank page detected by the blank page detection unit is to be excluded from a printing target, and a setting unit is provided for setting a printing target to be double-sided printed by the printing unit from the image data read sequentially in accordance with a result of the blank page skip determination, wherein, when the original stack is an original stack having a single-sided original stack on an upper side and a double-sided original stack on a lower side, the setting unit sequentially reads image data of the first and second sides of the separated and transported original sheets with the reading unit, performs a blank page skip determination as to whether or not the blank page detected by the blank page detection unit is to be excluded from a printing target, and sets a printing target to be double-sided printed by the printing unit from the image data read sequentially in accordance with a result of the blank page skip determination, the setting unit suspends the blank page skip determination for the first original sheet until a subsequent second original sheet appears, at least one of the first and second sides of which is not blank, when the blank page detection unit detects that only one of the first and second sides of a first original sheet separated and transported from the original stack is a blank side and the total number of pages to be printed from a leading sheet of the original stack to a sheet immediately preceding the first original sheet is an even number. is detected as a blank side by the blank page detection unit, the blank page skip determination determines that the blank side of the first manuscript sheet should be excluded from the printing target, and the non-blank side of the first manuscript sheet is added to the printing target; and when both the first and second sides of the second manuscript sheet are detected as non-blank sides by the blank page detection unit, the blank page skip determination determines that the blank side of the first manuscript sheet should not be excluded from the printing target, and both the blank side and non-blank side of the first manuscript sheet are added to the printing target.

[0009] In order to solve the above problem, an image forming apparatus according to claim 4 of the present invention includes an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a printing unit capable of double-sided printing, and a blank sheet detection unit that detects whether the first side is a blank side or a non-blank side and detects whether the second side is a blank side or a non-blank side based on the image data of the first and second sides read by the reading unit. a detection unit, and a setting unit for setting a print target to be double-sided printed by the printing unit from the image data read sequentially in accordance with a result of the blank paper skip determination, in a case where the document stack is a mixture of a single-sided document stack on an upper side and a double-sided document stack on a lower side, the setting unit sequentially reads image data of the first and second sides of the separated and transported document sheets by the reading unit, performs a blank paper skip determination as to whether or not the blank surfaces detected by the blank paper detection unit should be excluded from a print target, and sets a print target to be double-sided printed by the printing unit from the image data read sequentially in accordance with a result of the blank paper skip determination, When at least one of the first and second sides of the fed first original sheet is detected as a blank side by the blank page detection unit, it is determined in the blank page skip determination that the blank side of the first original sheet is to be excluded from the printing target, and when the first original sheet has a non-blank side, the non-blank side is added to the printing target, and when both the first and second sides of the first original sheet are detected as non-blank sides by the blank page detection unit and the total number of pages to be printed from the top sheet of the original stack to the sheet immediately preceding the first original sheet is If the number is odd, a blank page to be printed is inserted immediately before the first side of the first manuscript sheet, and the non-blank side of the first manuscript sheet is added to the pages to be printed; if the blank page detection unit detects that both the first and second sides of the first manuscript sheet are non-blank sides and the total number of pages to be printed from the first sheet of the manuscript stack to the sheet immediately before the first manuscript sheet is an even number, the blank page to be printed is not inserted and the non-blank side of the first manuscript sheet is added to the pages to be printed.

[0010] In order to solve the above problem, an image forming apparatus according to claim 11 of the present invention is an image forming apparatus comprising: an automatic document feeder which separates and conveys document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side which is one side of the separated and conveyed document sheets and a second side which is the other side of the separated and conveyed document sheets; a printing unit capable of double-sided printing; and a blank paper detection unit which detects whether the first side is a blank side or a non-blank side and detects whether the second side is a blank side or a non-blank side based on the image data of the first and second sides read by the reading unit, wherein the document stack is a stack of single-sided documents on the upper side and a stack of double-sided documents on the lower side. and a setting means for setting a print target to be double-sided printed by the printing unit from the image data read sequentially in accordance with the result of the blank-page skip determination, in which, when the stack of single-sided documents is a mixed stack of single-sided documents, the image data of the first and second sides of the separated and transported document sheets are read sequentially by the reading unit, a blank-page skip determination is made as to whether or not the blank sides detected by the blank-page detection unit should be excluded from the print target, and the setting means sets the print target to be double-sided printed by the printing unit from the image data read sequentially in accordance with the result of the blank-page skip determination, in which, when the stack of single-sided documents is an odd number of sheets, the setting means sets the print target so that the back side of the sheet on which the last page of the single-sided document is printed in the output of the double-sided printing of the stack of documents by the printing unit will be blank. Effect of the Invention

[0011] According to the present invention, when both sides of a mixed stack of single-sided and double-sided documents are scanned and then double-sided printed, the print results can be sorted by the original documents. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a hardware configuration of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing the internal configuration of the scanner appearing in FIG. [Diagram 3] 2 is a block diagram showing a schematic software configuration of a scanner I / F appearing in FIG. 1. [Figure 4] 2 is a block diagram showing a schematic software configuration of a scanner image processing unit appearing in FIG. 1. [Diagram 5] FIG. 5 is a block diagram showing a software configuration of the processing block in FIG. 4. [Figure 6] 6 is a diagram for explaining an example of the operation of a frequency distribution generating unit and a frequency distribution analyzing unit in FIG. 5. FIG. [Figure 7] 2 is a diagram showing an example of a copy setting screen displayed on a display unit of an operation unit appearing in FIG. 1. [Figure 8] 13 is a flowchart of a blank page removal+"double-sided to double-sided" copy execution process. [Figure 9] 9 is a flowchart of a subroutine of blank paper skip reading processing in step S803 of FIG. 8 according to the first embodiment. [Figure 10A] FIG. 10 is a table showing blank page skip determination conditions in a single-sided / double-sided original mixed mode in the blank page skip reading process of FIG. 9. [Figure 10B] FIG. 10B is a schematic diagram specifically illustrating condition 1 in FIG. 10A. [Figure 10C] FIG. 10B is a schematic diagram specifically illustrating condition 2 in FIG. 10A. [Figure 10D] FIG. 10B is a schematic diagram specifically illustrating condition 3 in FIG. 10A. [Figure 10E] FIG. 10B is a schematic diagram specifically illustrating condition 4 in FIG. 10A. [Figure 11] FIG. 11 is a schematic diagram showing a case where blank skip reading processing in a mixed single-sided / double-sided original mode in the first embodiment is performed on an original stack consisting of a stack of three single-sided originals on the upper side and a stack of two double-sided originals on the lower side. [Figure 12] FIG. 11 is a schematic diagram showing a case where blank skip reading processing in a mixed single-sided / double-sided original mode in the first embodiment is performed on an original stack consisting of a stack of four single-sided originals on the upper side and a stack of two double-sided originals on the lower side. [Figure 13] 13 is a flowchart of a subroutine of blank paper skip reading processing in step S803 of FIG. 8 according to the second embodiment. [Figure 14]FIG. 14 is a table showing blank page skip determination conditions in the single-sided / double-sided original mixed mode in the blank page skip reading process of FIG. 13. [Figure 15] FIG. 11 is a schematic diagram showing a case where blank-page skip reading processing in a mixed single-sided / double-sided original mode in the second embodiment is performed on an original stack consisting of a stack of three single-sided originals on the upper side and a stack of two double-sided originals on the lower side. [Figure 16] 13 is a schematic diagram showing a case where blank-page skip reading processing in a mixed single-sided / double-sided original mode in the second embodiment is performed on an original stack consisting of a stack of four single-sided originals on the upper side and a stack of two double-sided originals on the lower side. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims, and all of the combinations of features described in the embodiments are not necessarily essential to the solution of the invention.

[0014] <First embodiment> A first embodiment of the present invention will be described.

[0015] FIG. 1 is a block diagram showing the hardware configuration of an image forming apparatus 101 according to this embodiment.

[0016] In FIG. 1, an image forming apparatus 101 includes a control unit 102 , an operation unit 112 , a printer 113 , a scanner 114 , and a modem 115 .

[0017] The control unit 102 controls the overall operation of the image forming apparatus 101. As shown in Fig. 1, the control unit 102 includes a CPU 103, a ROM 104, a RAM 105, a HDD 106, an operation unit I / F 107, a printer I / F 108, a scan I / F 109, and a modem I / F 110. The control unit 102 also includes a network I / F 111, a scanner image processing unit 116, an encoding / decoding unit 117, and a system bus 118.

[0018] The CPU 103 reads out a control program stored in the ROM 104 and performs various controls such as reading, printing, and communication.

[0019] The RAM 105 is used as a temporary storage area such as a main memory and a work area for the CPU 103, and the HDD 106 stores image data and various programs.

[0020] The operation unit I / F 107 connects the operation unit 112 and the control unit 102. The operation unit 112 is equipped with a display unit and keys (buttons) (not shown), and serves as a reception unit that receives operations / inputs / instructions from the user. The display unit of the operation unit 112 is a touch panel, and the user can give input instructions and scroll instructions by touching the screen.

[0021] The printer I / F 108 connects the printer 113 and the control unit 102. Image data to be printed by the printer 113 is transferred from the control unit 102 via the printer I / F 108, and is printed on a recording material by the printer 113. In this embodiment, the printer 113 (printing unit) is capable of single-sided printing and double-sided printing.

[0022] The scanner I / F 109 connects the scanner 114 and the control unit 102. The scanner 114 (reading unit) reads an image on a document, generates image data, and inputs the image data to the control unit 102 via the scanner I / F 109.

[0023] The scanner image processing unit 116 is a processing unit that executes image processing according to an image processing mode (color scan, monochrome scan, etc.) on the image data expanded in the RAM 105 by the processing of the scanner I / F 109. The scanner I / F 109 and the scanner image processing unit 116 will be described in detail later.

[0024] The encoding / decoding unit 117 is a processing unit that executes compression and decompression processing of image data in accordance with a predetermined standard such as JPEG or JBIG.

[0025] The modem I / F 110 connects the modem 115 to the control unit 102. The modem 115 is connected to a public line and executes facsimile communication of image data with an external facsimile device (not shown).

[0026] The network I / F 111 connects the control unit 102 (image forming apparatus 101) to a wired LAN (not shown). The image forming apparatus 101 can transmit and receive image data and various information to and from an external device via the network I / F 111. For example, the image forming apparatus 101 can receive print image data from an external device and print it using a printer 113, or transmit image data read by a scanner 114 to the external device.

[0027] The system bus 118 provides a data pathway between the structural elements described above within the control unit 102 .

[0028] Next, the internal configuration of the above-mentioned scanner 114 will be described with reference to FIG.

[0029] The scanner 114 comprises a lower scanner portion 201 and an upper scanner portion 202 .

[0030] The scanner lower part 201 includes a platen 203 and a contact image sensor (CIS) 204. The platen 203 is made of a transparent plate such as a glass plate.

[0031] The scanner upper portion 202 includes a document tray 205, a paper discharge tray 206, and an automatic document feeder (ADF) 207. The document tray 205, the paper discharge tray 206, and the ADF 207 are integrally configured.

[0032] An original 208 placed on an original tray 205 is taken into the ADF 207, the image is read, and the original is discharged to a discharge tray 206. The scanner 114 (FIG. 1) can read one side or both sides of the original 208 by using the ADF 207. The upper scanner part 202 can be opened and closed relative to the lower scanner part 201 by an opening and closing mechanism (not shown). By opening and closing the upper scanner part 202, the scanner 114 can read the image of the original placed on the original table 203 without using the ADF 207.

[0033] The CIS 204 in the scanner lower portion 201 functions as an image reading unit for one side of a document. Hereinafter, in this embodiment, the side read by the CIS 204 is referred to as the "front side." Therefore, the upper side of the document 208 placed on the document tray 205 is the front side. The side opposite the front side is referred to as the "back side."

[0034] The CIS 204 includes a pair of LED (Light Emitting Diode) light sources 209 and 210 as irradiation means, a photoelectric conversion unit 211, and a lens 212.

[0035] Light emitted from LED light sources 209 and 210 is reflected by the surface of an original 208 taken in by ADF 207 or the surface of an original placed on platen 203 , and the reflected light is input to photoelectric conversion unit 211 via lens 212 .

[0036] The photoelectric conversion unit 211 converts the input reflected light into an electrical signal to generate image data.

[0037] The LED light source 209 has a plurality of LED elements and a light guide arranged along the main scanning direction (depth direction in FIG. 2). Similarly, the LED light source 210 has a plurality of LED elements and a light guide arranged along the main scanning direction. The LED light sources 209 and 210 illuminate the surface of the document via the light guide with light emitted from each LED element. The photoelectric conversion unit 211 has a plurality of photoelectric elements arranged in the main scanning direction.

[0038] The CIS 204 thus configured is provided movable in the sub-scanning direction (the left-right direction in FIG. 2) below the platen 203. When an original is placed on the platen 203, the CIS 204 moves in the sub-scanning direction to read the image of the original.

[0039] The ADF 207 of the scanner upper portion 202 functions as a document transport unit. The ADF 207 transports documents 208 placed on a document tray 205 one by one to a paper discharge tray 206. To this end, the ADF 207 includes a pickup roller 213, a separation section 214, a first registration roller 215, a second registration roller 216, a first transport roller 217, a second transport roller 218, and a paper discharge roller 219 along a transport path.

[0040] The CIS 221 of the scanner upper portion 202 functions as an image reading unit for the other side, that is, the back side, of the document 208 .

[0041] The CIS 221 includes a pair of LED light sources 222 and 223 as irradiation means, a photoelectric conversion unit 224 , and a lens 225 .

[0042] Light emitted from LED light sources 222 and 223 is reflected by the back surface of the document taken in by ADF 207 , and the reflected light is input to photoelectric conversion unit 224 via lens 225 .

[0043] The photoelectric conversion unit 224 generates image data by converting the input reflected light into an electrical signal.

[0044] The LED light source 222 has a plurality of LED elements and a light guide arranged along the main scanning direction. Similarly, the LED light source 223 has a plurality of LED elements and a light guide arranged along the main scanning direction. The LED light sources 222 and 223 illuminate the back surface of the document through the light guide with light emitted from each LED element. The photoelectric conversion unit 224 has a plurality of photoelectric elements arranged in the main scanning direction.

[0045] The ADF 207 takes in the original 208 placed on the original tray 205 by the pickup roller 213. The separation unit 214 is configured with a separation roller at the top and a separation pad at the bottom in the figure, and separates the original 208 taken in by the pickup roller 213 one by one. The ADF 207 can take in the original 208 one by one continuously by the pickup roller 213 and the separation unit 214. The first registration roller 215 performs skew correction on the taken-in original 208. The skew-corrected original 208 is transported by the second registration roller 216 and the first transport roller 217 to an image reading position by the CIS 204 and the CIS 221. When only the front side of the original 208 is to be read, the front side image is read by the CIS 204, and when both the front and back sides are to be read, the front side image is read by the CIS 204 and the back side image is read by the CIS 221. The document, whose image has been read by the CIS 204 and the CIS 221 , is discharged onto the discharge tray 206 by a second transport roller 218 and a discharge roller 219 .

[0046] With the configuration described above, the scanner 114 is capable of reading an image on the front side of a document placed on the document table 203, reading an image on only the front side (one side) of a document 208 captured by the ADF 207, and simultaneously reading images on both the front and back sides (both sides) of the document 208.

[0047] FIG. 3 is a block diagram showing a schematic software configuration of the scanner I / F 109 appearing in FIG.

[0048] The scanner I / F 109 is composed of a front side image data input block 301 used for reading an image on the front side of a document by the scanner 114, and a back side image data input block 302 used for reading an image on the back side of a document by the scanner 114. In the image forming apparatus 101 of the present invention, the image data read by the CIS 204 is input to the front side image data input block 301, and the image data read by the CIS 221 is input to the back side image data input block 302.

[0049] First, the front surface image data input block 301 will be described.

[0050] The first timing control unit 303 generates and outputs a control signal for the reading device corresponding to the reading speed to the CIS 204. This device control signal is synchronized with a synchronization signal generated in the scanner I / F 109, and thus the reading timing in the main scanning direction and the reading process can be synchronized. The first LED lighting control unit 304 is a unit that controls the lighting of the LEDs 209 and 210 that are the light sources of the CIS 204. The first LED lighting control unit 304 executes a synchronization signal for sequential lighting control of the LEDs 209 and 210 corresponding to each color element of R, G, and B, a clock signal, and dimming control corresponding to the CIS 204, starting lighting, and turning off the lights. This control timing is based on a synchronization signal received from the above-mentioned first timing control unit 303, and lighting of the LEDs 209 and 210 is controlled in synchronization with the driving of the CIS 204. The output signal of the CIS 204 is input to a first AFE (AFE: Analog Front End) 305. The first AFE 305 performs gain adjustment and A / D conversion processing on the output signal of the CIS 204, converts the analog signal output from the CIS 204 into a digital signal, and inputs it to the front image data input block 301. The first synchronization control unit 306 sets a predetermined threshold level for the first AFE 305 according to the analog signal of the CIS 204, and adjusts the output signal level according to the difference in the image reading device. Furthermore, it generates and outputs a synchronization clock for sampling control of the analog signal and outputting a digital signal to the first AFE 305, and receives read image data by a predetermined digital signal from the first AFE 305. The image data received from the first AFE 305 is input to the first output data control unit 307 via the first synchronization control unit 306. The first output data control unit 307 stores the input image data in the buffer 308 (buffer A-1, buffer B-1, buffer C-1) according to the output mode of the front image data input block 301. The image data stored in the buffer 308 is transferred to the RAM 105.

[0051] Next, the back image data input block 302 will be described. The back image data input block 302 has the same configuration as the above-mentioned front image data input block 301. For the CIS 221, the second timing control unit 309 generates and outputs a control signal for the reading device according to the reading speed. The second LED lighting control unit 310 controls the lighting of the LEDs 222 and 223 that are the light sources of the CIS 221. The output signal of the CIS 221 is input to the second AFE 311, where it is subjected to gain adjustment and A / D conversion processing, and input to the back image data input block 302. The second synchronization control unit 312 sets a predetermined threshold level for the second AFE 311 according to the analog signal of the CIS 221, and adjusts the output signal level according to the difference in the image reading device. Furthermore, it generates and outputs a synchronization clock for sampling control of the analog signal and outputting a digital signal to the second AFE 311, and receives read image data by a predetermined digital signal from the second AFE 311. This data is input to the second output data control unit 313. The second output data control unit 313 stores the received image data in a buffer 314 (buffer A-2, buffer B-2, buffer C-2) in accordance with the output mode of the back-side image data input block 302. The image data stored in the buffer 314 is transferred to the RAM 105.

[0052] Next, the schematic software configuration of the scanner image processing unit 116 will be described with reference to FIG.

[0053] The scanner image processing unit 116 is a processing unit that executes image processing according to an image processing mode (color scan, monochrome scan, etc.) on the image data expanded in the RAM 105 by the processing of the scanner I / F 109 described with reference to Fig. 3. The scanner image processing unit 116 is composed of a front scanner image processing unit 400 and a back scanner image processing unit 410.

[0054] First, the surface scanner image processing unit 400 will be described.

[0055] The surface scanner image processing unit 400 executes processing according to each image processing mode on the data loaded into the scanner image processing buffer 408. Here, the image data transferred to the RAM 105 as output data of the surface image data input block 301 of the scanner I / F 109 described above is loaded into the scanner image processing buffer 408 sequentially in units of a predetermined data size.

[0056] The processing block 401 is a processing block that reconstructs the frame-sequential input data separated into R, G, and B into dot-sequential data. Data for one pixel is stored in the RAM 105 as frame-sequential data for each color of R, G, and B. When this data is loaded into the scanner image processing buffer 408, the processing block 401 extracts one pixel data for each color data and reconstructs it as R, G, and B data for one pixel. Next, the processing block 401 performs reconstruction processing for each pixel, converting the frame-sequential image data into dot-sequential data.

[0057] The processing block 402 is a processing block that executes shading correction to compensate for variations in the light amount distribution of the light source (LEDs 209, 210) in the main scanning direction, variations in the light receiving elements (photoelectric elements of the photoelectric conversion unit 211) of the image reading device, and offsets the dark output.

[0058] The processing block 403 is a processing block that performs averaging processing, input masking processing, and gamma correction processing. The averaging processing here is processing for lowering the reading resolution in the main scanning direction, and subsampling (simple thinning) may be performed instead of averaging processing. The input masking processing here is processing for calculating color correction of input R, G, B data, and the gamma correction processing is processing for giving a predetermined gradation characteristic to the input data.

[0059] A processing block 404 is a processing block that determines whether each pixel of the input image data is a black character or a line drawing contour.

[0060] The processing block 405 is a processing block that performs MTF correction processing, RGB → (L, Ca, Cb) conversion processing, and background density adjustment processing. Here, the MTF correction processing is processing that performs filter processing in the main scanning direction to correct the MTF difference when the image reading device is changed and to reduce moire when reducing the magnification, and performs multiplication and addition processing of each coefficient for a predetermined pixel in the main scanning direction of the target area. Also, the RGB → (L, Ca, Cb) conversion processing is processing that converts multi-value image data (RGB data) of each color of R, G, and B when filtering (L (brightness emphasis), Ca (saturation emphasis), Cb (color judgment)) performed in the subsequent processing block 406. The background density adjustment processing unit is processing for automatically recognizing the background density of the document and correcting the background density value to the white side to obtain binary data suitable for facsimile communication, etc.

[0061] In order to perform color judgment and filtering on the data that has been converted from RGB to (L, Ca, Cb) in the previous processing block 405, the processing block 406 first performs edge intensity processing on the lightness component (L) of the input image and emphasis processing (filter processing) on ​​the saturation (Ca, Cb). Furthermore, the processing block 406 performs color judgment on the input image after the edge intensity processing and outputs the result. The processing block 406 can also change the parameter of the amount of emphasis based on judgment signals of characters and line drawing contours generated in the processing block 404. The data after the filtering processing in the processing block 406 is converted from (L, Ca, Cb) data to RGB data and output. When processing monochrome image data, this processing block 406 functions as an edge emphasis filter.

[0062] A processing block 407 is a processing block that performs linear interpolation magnification processing in the main scanning and sub-scanning directions.

[0063] The above image processing is sequentially performed on the data loaded into the scanner image processing buffer 408 according to the set image processing mode (copy mode, scanner mode, etc.).

[0064] The processing block 409 (blank paper detection unit) performs detection (blank paper determination) of whether the read image data is blank or not for the image data input to the surface scanner image processing unit 400 in parallel with the above-mentioned image processing. Here, blank paper refers to a document that is determined to have no printed information (i.e., content). If there is no printed information, colored documents such as colored paper and recycled paper are also treated as blank. In other words, blank paper detection is a determination of the presence or absence of content printed on the document. In addition, image data when these are read and image data when only the back side is read are also called blank paper hereinafter. On the other hand, a document written with a small amount of characters or faint characters printed with halftone dots is not blank. Image data obtained by reading paper containing printed information written by hand or printed by a printer is called content data. The processing block 409 detects blank paper by, for example, calculating the average value and variance from the frequency distribution of the input image data. This is because a feature that the variance calculated from the frequency distribution becomes large is used when the read image data of the document contains significant information (information that is not blank, content).

[0065] FIG. 5 is a block diagram showing the software configuration of the processing block 409 in FIG.

[0066] The processing block 409 is a block having a frequency distribution generating unit 501 and a frequency distribution analyzing unit 502, and is connected to a register (not shown), in which control parameters and processing results are stored. Writing to the register is performed by the CPU 103 and the processing block 409, and the processing block 409 operates by reading out the control parameters set in the register and writes the processing results to the register.

[0067] A frequency distribution generating unit 501 generates a luminance frequency distribution from input image data, and a frequency distribution analyzing unit 502 analyzes the characteristics of the frequency distribution generated by the frequency distribution generating unit 501 and determines whether the document image is blank or not.

[0068] Here, an example of the operation of the frequency distribution generating unit 501 and the frequency distribution analyzing unit 502 will be described with reference to FIG.

[0069] 6A and 6B, the horizontal axis indicates pixel values ​​when the precision of the input image data is 8 bits (range: 0 to 255), and the vertical axis indicates the frequency. In the example shown in Fig. 6, the image data read by the scanner 114 is luminance information, and the closer the data is to white, the larger the numerical value, and the closer the data is to black, the smaller the numerical value.

[0070] When the background of the reading surface of the document is white paper, the pixel values ​​(brightness information) of the read image data become large, and the frequency distribution generated by the frequency distribution generating unit 501 becomes concentrated at high brightness, as shown in FIG. 6(A).

[0071] Here, each pixel value x n and its average value x ave Using the following formula, the variance s 2 can be sought.

[0072]

number

[0073] dispersion s 2 The smaller the value (the closer to zero), the smaller the average value x ave and each pixel value x n It is a numerical indicator that shows that there is little difference (variation) between the

[0074] As shown in Figure 6(A), the average value x ave Each pixel value x n For manuscripts where the variance of s is small, 2 The value of x is relatively small. On the other hand, if the read image data contains information, the frequency is distributed to luminance values ​​other than high luminance, as shown in FIG. 6(B). In this case, the average value x ave Each pixel value x n The variance of s 2The value of s is relatively large. From these facts, it becomes possible for the frequency distribution analysis unit 502 to determine whether the scanned image data is blank or not by calculating the average value and variance obtained from the frequency distribution. In this example, the frequency distribution analysis unit 502 calculates the variance s 2 Calculate the variance s 2 is a given threshold s 2 thresh If the variance exceeds s, the scanned image data is determined to be not blank. 2 is a given threshold s 2 thresh The scanned image data is determined to be blank if the following is true: The reason for using the variance value to determine whether a page is blank is that by dividing the scanned image data into multiple regions and calculating the frequency distribution and variance for each divided region, it is possible to determine whether a page is blank while taking into account the variation between regions.

[0075] In the example shown in Fig. 6, the processing block 409 uses a method for detecting blank pages using the frequency distribution and variance of the read image data, but the method for detecting blank pages in the present invention is not limited to this method. For example, a processing unit for detecting edges in the read image data may be provided, pixels determined to be edges may be counted, and blank pages may be detected according to the count value (number of edges). Also, a blank page may be determined by combining the frequency distribution, variance, and number of edges.

[0076] When performing a blank page determination, the image forming apparatus 101 sets a blank page detection level in accordance with, for example, a user operation. The blank page detection level is a detection level at which image data is detected as being blank.

[0077] For example, the threshold s 2 thresh By reducing the variance s 2 is the threshold s 2 thresh However, the tendency for the page to exceed the threshold s 2 thresh Increasing s 2 is the threshold s 2 threshThe tendency for the page to be below the threshold s becomes stronger and the page is more likely to be judged as blank. 2 thresh By changing the value of , you can change the standard for determining whether a page is blank. In other words, if you do not want a document that contains a lot of faint text or image data to be determined to be blank, you can set the blank page detection level to a low level (threshold s 2 thresh Conversely, if you want documents that contain a lot of faint text or image data to be determined as blank, set the blank page detection level to strong (threshold value s 2 thresh (increase the value of ).

[0078] Next, the back side scanner image processing unit 410 will be described.

[0079] The back scanner image processing unit 410 has the same configuration as the above-mentioned front scanner image processing unit 400. The back scanner image processing unit 410 executes processing according to each image processing mode on the data loaded into the scanner image processing buffer 418. Here, the image data transferred to the RAM 105 as output data of the back image data input block 302 of the scanner I / F 109 described above is loaded into the scanner image processing buffer 418 sequentially for each predetermined data size.

[0080] The processing blocks 411 to 417, 419 respectively perform the same processes as the corresponding processing blocks 401 to 407, 409 of the above-mentioned surface scanner image processing unit 400. Therefore, detailed description thereof will be omitted here.

[0081] 7 shows an example of a job setting for reading a stack of originals containing an odd number of single-sided originals and double-sided originals from the ADF and performing blank page removal + "double-sided to double-sided" copying with the image forming apparatus 101 of the present invention. Note that "double-sided to double-sided" copying refers to a job in which image data on both sides of the original sheets taken in from the stack of originals by the ADF is read, and then double-sided printing is performed using the read image data.

[0082] 7 are displayed on the display unit of the operation unit 112 under the control of the CPU 103. In this embodiment, a mixture of single-sided and double-sided documents refers to a state in which a stack of single-sided documents is read by the ADF 207, and then documents 208 are placed on the document tray 205 so that double-sided documents can be read.

[0083] 7A is a standby screen for the copy function in the image forming apparatus 101. As shown in the figure, the standby screen in FIG. 7A includes a basic setting item area 701, a detailed setting item area 702, and a start button 703.

[0084] In the basic setting item area 701, the basic settings of color selection (full color / black and white), magnification, paper (cassette / size), and number of copies can be changed.

[0085] In the detailed setting item area 702, detailed settings of the print job such as double-sided printing, blank page skip, sorting, document type, page aggregation (Nup), etc. can be changed. Although not shown in Fig. 7A, in addition to the above-mentioned items, detailed setting items that can be changed in the detailed setting item area 702 include border erasure, sharpness, density, etc. These detailed setting items are displayed when the user touches the detailed setting item area 702 on the display unit (touch panel) of the operation unit 112 and scrolls it.

[0086] A start button 703 is a button for accepting an instruction to start a copy job with the job settings at the time the button is pressed by the user.

[0087] When performing blank page removal + “double-sided to double-sided” copying using the image forming apparatus 101 of the present invention, the user changes the detailed settings of the copy job using the “double-sided” setting 704 and the “skip blank page” setting 705 in the detailed setting item area 702.

[0088] When the user presses the "Double-Sided" setting 704 on the standby screen of Fig. 7(A), the double-sided setting screen of Fig. 7(B) is displayed. On the double-sided setting screen of Fig. 7(B), the user selects the "Double-Sided → Double-Sided" copy setting 706, and then presses the Confirm button 707 to close the screen and redisplay the standby screen of Fig. 7(A). This operation causes the image forming apparatus 101 to set a copy job in which the image forming apparatus reads the front and back sides of the document and prints out the front and back sides of the print paper.

[0089] When the user presses the "skip blank page" setting 705 on the standby screen of Fig. 7(A), the blank page skip setting screen of Fig. 7(C) is displayed. When the user selects the "ON" setting 708 on the blank page skip setting screen of Fig. 7(C) and then presses the "mixed single-sided / double-sided originals" button 710, the mixed single-sided / double-sided originals setting screen of Fig. 7(D) is displayed.

[0090] After the user selects "ON" setting 713 on the single-sided / double-sided original mixed setting screen in Fig. 7(D), the user presses Confirm button 714 to close the screen. Furthermore, the user presses Confirm button 711 on the blank page skip setting screen in Fig. 7(C) that is redisplayed by this operation to close the screen and redisplay the standby screen in Fig. 7(A).

[0091] By the above operations, the job settings for the copy job are set to the mixed single-sided / double-sided original mode and the blank page skip setting in the image forming apparatus 101. When the start button 703 is pressed in this state, the image forming apparatus 101 starts executing a blank page removal + "double-sided → double-sided" copy, which will be described later using the flowcharts in Figures 8 and 9.

[0092] Incidentally, a dedicated button for blank page removal and "double-sided to double-sided" copying may be provided on operation unit 112. In this case, the user can start blank page removal and "double-sided to double-sided" copying on image forming apparatus 101 simply by pressing this dedicated button. This dedicated button may be an icon displayed on the display unit of operation unit 112, or may be a physical button on operation unit 112.

[0093] Furthermore, when the user presses "detection level adjustment" button 709 on the blank page skip setting screen in Fig. 7(C), the detection level adjustment screen in Fig. 7(E) is displayed. In image forming apparatus 101 of the present invention, the detection level can be changed in five stages, and after the user slides slider 715 to set the desired detection level, the user presses confirmation button 716 to close the screen, and the change to the set detection level is confirmed.

[0094] Furthermore, when the user presses the "?" button (help button) 712 on the blank page skip setting screen in Fig. 7(C), the help screen in Fig. 7(F) is displayed. The help screen in Fig. 7(F) informs the user of detailed explanations of the mixed single-sided / double-sided document mode and the detection level adjustment. When the user presses close 717, the blank page skip setting screen in Fig. 7(C) is displayed again.

[0095] Next, referring to Figures 8 and 9, a process will be described in which a stack of documents containing a mixture of an odd number of single-sided documents and double-sided documents is read from the ADF using the image forming apparatus 101 of this embodiment, and blank page removal + "double-sided to double-sided" copying is performed.

[0096] 8 is a flowchart of the blank page removal+"double-sided to double-sided" copy execution process. This process is executed by the CPU 103 (setting means) loading a program stored in the ROM 104 onto the RAM 105.

[0097] The following describes a case where a stack of originals (mixed stack of originals) with an odd number of single-sided originals on the top and a stack of double-sided originals on the bottom is placed on original tray 205 of the ADF and this process is executed.

[0098] First, in step S801, CPU 103 accepts job setting input from the user via operation unit 112. Here, to execute blank page removal + "double-sided to double-sided" copying, the user sets detailed settings for the copy job using each screen in Fig. 7 described above, turns on mixed single-sided / double-sided original mode, and turns on blank page skip setting.

[0099] Next, in step S802, CPU 103 accepts a copy job start instruction from the user via operation unit 112. Here, the user places the documents on document tray 205 in a stack with the single-sided documents on top and the double-sided documents on the bottom, and presses start button 703 in Fig. 7A to instruct the start of a copy job.

[0100] Next, in step S803, CPU 103 executes blank-page skip reading processing. Specifically, in blank-page skip reading processing, first, original sheets of a stack of originals placed on original tray 205 are separated and conveyed one by one from the top, and image data of the front and back sides are read. At this time, blank sides are skipped based on the blank page determination result of processing block 409 (blank sides are excluded from the printing target). After that, the read image data to be printed is stored sequentially. Details of this series of blank-page skip reading processing will be explained later using the subroutine of FIG. 9.

[0101] Next, in step S804, CPU 103 outputs the scanned image data to be printed, stored in step S803, on both sides of a printing sheet by double-sided printing.

[0102] In the flowchart of Fig. 8, after double-sided reading, the blank pages are skipped and the obtained image data to be printed is subjected to double-sided printing processing, but the control method of the present invention is not limited to this method. For example, a configuration in which double-sided reading, blank page skipping, and double-sided printing are each performed in parallel may be used.

[0103] FIG. 9 is a flowchart of the blank page skip reading process subroutine in step S803 in FIG.

[0104] First, in step S 901 , the CPU 103 reads images on both the front and back sides of one original sheet separated and conveyed from a stack of originals placed on the original tray 205 of the scanner 114 .

[0105] In step S902, if there is a blank surface, CPU 103 sets the document sheet read in step S901 as the target sheet (hereinafter referred to as the "current sheet") for determining whether or not to skip the blank surface, i.e., exclude it from the printing target (blank skip determination).

[0106] In step S903, CPU 103 determines whether or not the single-sided / double-sided original mixed mode is ON. If it is ON (YES in step S903), the process proceeds to step S904; if not, the process proceeds to step S905.

[0107] In step S904, CPU 103 determines whether or not both the front and back sides of the current sheet are blank. If both the front and back sides are blank (YES in step S904), the process proceeds to step S909; otherwise, the process proceeds to step S910.

[0108] In step S905, CPU 103 determines whether the current sheet has a blank side, that is, whether at least one of the front and back sides is blank. If the current sheet has a blank side (YES in step S905), the process proceeds to step S906; otherwise, the process proceeds to step S907.

[0109] In step S906, CPU 103 skips the blank page of the current sheet, and advances the process to step S907.

[0110] In step S907, CPU 103 determines whether the current sheet has a non-blank side, that is, whether at least one of the front and back sides is a non-blank side (a side that is not blank). If the current sheet has a non-blank side (YES in step S907), the process proceeds to step S908; otherwise, the process proceeds to step S922.

[0111] In step S908, CPU 103 adds the non-blank sides of the current sheet to the pages to be printed, and proceeds to step S922.

[0112] In step S909, CPU 103 skips both the front and back sides of the current sheet, that is, excludes them from the printing target, and proceeds to step S922.

[0113] In step S910, CPU 103 determines whether there is a reserved sheet pending blank skip determination. If there is no reserved sheet (YES in step S910), the process proceeds to step S911. If not, the process proceeds to step S917.

[0114] In step S911, CPU 103 determines whether either the front or back side of the current sheet is blank. If either side is blank (YES in step S911), the process proceeds to step S912. If not (both the front and back sides of the current sheet are non-blank), the process proceeds to step S915.

[0115] In step S912, CPU 103 calculates the total number of pages to be printed up to the sheet immediately preceding the current sheet, and proceeds to step S913. However, if the current sheet is the first sheet, there is no sheet before that, so the total number of pages to be printed up to the sheet immediately preceding the current sheet is treated as "0" (zero).

[0116] In step S913, CPU 103 determines whether the total number of pages to be printed calculated in step S912 is an odd number. If it is an odd number (YES in step S913), the process proceeds to step S914. If it is not (an even number), the process proceeds to step S916.

[0117] In step S914, CPU 103 skips the blank side of the current sheet, that is, excludes it from the printing target, and proceeds to step S915.

[0118] In step S915, CPU 103 adds the non-blank surface of the current sheet to the printing target, and proceeds to step S916.

[0119] In step S916, CPU 103 sets the current sheet as a reserved sheet, reserves the skip determination for blank pages, and advances the process to step S922.

[0120] In step S917, CPU 103 determines whether either the front or back side of the current sheet is blank. If either side is blank (YES in step S917), the process proceeds to step S918. If not (both the front and back sides of the current sheet are non-blank), the process proceeds to step S921.

[0121] In step S918, CPU 103 skips the blank sides of the reserved sheets, that is, excludes them from the printing targets, and proceeds to step S919.

[0122] In step S919, CPU 103 adds the non-blank sides of the reserved sheets to the printing targets, and proceeds to step S920.

[0123] In step S920, the CPU 103 clears the information on the reserved sheets, and the process proceeds to step S911.

[0124] In step S921, CPU 103 adds each of the front and back sides of the reserved sheet to the printing targets without adding the non-blank side of the reserved sheet to the printing targets, and proceeds to step S920.

[0125] In step S922, CPU 103 determines whether or not there is a next manuscript sheet. If there is a next manuscript sheet (YES in step S922), the process returns to step S901; otherwise, the process proceeds to step S923.

[0126] In step S923, CPU 103 determines whether or not there is a reserved sheet. If there is a reserved sheet (NO in step S923), the process proceeds to step S924; otherwise, the subroutine in FIG.

[0127] In step S924, CPU 103 skips the blank sides of the reserved sheets, that is, excludes them from the printing targets, and proceeds to step S925.

[0128] In step S925, CPU 103 adds the non-blank sides of the reserved sheets to the printing targets, and then ends the subroutine in FIG.

[0129] 9, the process is switched depending on whether the total number of pages to be printed up to the sheet immediately preceding the current sheet is an odd number, but the control method in the present invention is not limited to this method. For example, the same determination may be made using the number of sheets up to the sheet immediately preceding the current sheet and information on the number of pages skipped, or the number of pages read and the number of pages skipped.

[0130] Fig. 10A is a diagram showing a table of blank page skip determination conditions in the single-sided / double-sided original mixed mode in the blank page skip reading process of Fig. 9. As shown in Fig. 10A, in this embodiment, the blank page skip determination conditions in the single-sided / double-sided original mixed mode include conditions 1 to 4. Figs. 10B to 10E are diagrams showing specific schematic diagrams of conditions 1 to 4 shown in Fig. 10A, respectively.

[0131] The process contents determined by the blank page skip judgment condition are not only determined by information about the target sheet (first manuscript sheet), i.e., the blank page detection result of the target sheet and whether the total number of pages to be printed up to the sheet immediately before the target sheet is even or odd. As shown in Fig. 10A, the blank page detection result of the first sheet (second manuscript sheet) that is subsequent to the target sheet and has either the front or back side not blank also influences the process contents.

[0132] Next, using Figures 11 and 12, a specific example will be described in which the blank skip reading process in the single-sided / double-sided original mixed mode in this embodiment is executed by reading a stack of originals containing a mixture of single-sided and double-sided originals from the ADF.

[0133] FIG. 11 is a schematic diagram showing a case where the blank-page skip reading process in the mixed single-sided / double-sided original mode in this embodiment is performed on an original stack consisting of a stack of three single-sided originals on the upper side and a stack of two double-sided originals on the lower side.

[0134] As shown in FIG. 11(A), all three single-sided documents have blank pages on the back, and both double-sided documents have print information (content) on the front and back. When these documents are read, including the blank pages, the read image data shown in FIG. 11(B) is generated. Therefore, in this case, when the blank page skip read process of FIG. 9 is performed with the single-sided / double-sided document mixed mode ON, the blank pages W1 and W2 are skipped (removed) as shown in FIG. 11(C), and the blank page W3 is not skipped but is retained as a print target. Specifically, the blank page W1 is skipped because condition 4 in FIG. 10(A) is applied, and the blank page W2 is skipped because condition 2 in FIG. 10(A) is applied. The blank page W3 is not skipped because condition 3 in FIG. 10(A) is applied. The result of double-sided printing of the read image data of the page configuration after the blank page skip read process is shown in FIG. 11(D). That is, the first and second output sheets are the results of printing a single-sided document on both sides, and the third and fourth output sheets are the results of printing a double-sided document on both sides. In this way, the print results can be sorted according to the original documents (i.e., documents printed as single-sided documents and documents printed as double-sided documents).

[0135] FIG. 12 is a schematic diagram showing a case where the blank skip reading process in the mixed single-sided / double-sided original mode in this embodiment is performed on an original stack consisting of a stack of four single-sided originals on the upper side and a stack of two double-sided originals on the lower side.

[0136] As shown in FIG. 12(A), all four single-sided documents have blank pages on the back, and both double-sided documents have print information (content) on the front and back. When these documents are scanned including the blank pages, scanned image data as shown in FIG. 12(B) is generated. Therefore, in this case, when the blank page skip scanning process of FIG. 9 is performed with the single-sided / double-sided document mixed mode ON, blank pages W1, W2, W3, and W4 are skipped as shown in FIG. 12(C). Specifically, blank page W1 is skipped according to condition 4 in FIG. 10(A), blank page W2 according to condition 2 in FIG. 10(A), blank page W3 according to condition 4 in FIG. 10(A), and blank page W4 according to condition 2 in FIG. 10(A). The result of double-sided printing of scanned image data of the page configuration after the blank page skip is shown in FIG. 12(D). That is, the first and second output sheets are the results of printing a single-sided document on both sides, and the third and fourth output sheets are the results of printing a double-sided document on both sides. In this way, the print results can be sorted according to the original documents.

[0137] As described above, according to this embodiment, when the single-sided / double-sided original mixed mode is ON, blank pages are appropriately skipped when the single-sided original stack and the double-sided original stack in the original tray are read by the ADF during blank page removal + "double-sided to double-sided" copying. Therefore, the print target is set so that the back side of the sheet on which the last page of the single-sided original is printed in the output of the double-sided printing of the original stack is blank, and the print results can be sorted by original documents. Note that images of both sides of the original stack in the original tray may be scanned first. As a result, if it is determined that the single-sided original stack is an odd number of sheets, a warning may be issued before setting the print target to the effect that it will be impossible to output sorted by original documents if all blank pages detected in processing blocks 409 and 419 are excluded from the print target.

[0138] <Second embodiment> In the first embodiment, whether or not to skip a detected blank surface of a sheet of interest is determined based on a predetermined condition according to the number of pages to be printed up to the immediately preceding sheet and the blank surface detection status of the succeeding sheets.

[0139] On the other hand, in this embodiment, all detected blank pages are skipped. Also, if neither the front nor back side of the target sheet is blank, it is determined whether or not to insert a blank page to be printed immediately before the target sheet, based on a predetermined condition according to the number of pages to be printed up to the sheet immediately before the target sheet.

[0140] In this embodiment, the hardware configuration of the image forming apparatus 101 is the same as that of the first embodiment, and the processes other than the blank paper skip reading process are the same as those of the first embodiment. Therefore, the description of the parts of this embodiment that overlap with the first embodiment will be omitted here.

[0141] FIG. 13 is a flowchart of a subroutine of the blank paper skip reading process in step S803 of FIG. 8 according to the second embodiment of the present invention.

[0142] First, in step S 1301 , the CPU 103 reads images on both the front and back sides of one original sheet separated and conveyed from a stack of originals placed on the original tray 205 of the scanner 114 .

[0143] In step S1302, CPU 103 sets the original sheet read in step S1301 as the current sheet.

[0144] In step S1303, CPU 103 determines whether or not the single-sided / double-sided original mixed mode is ON. If it is ON (YES in step S1303), the process proceeds to step S1304; if not, the process proceeds to step S1305.

[0145] In step S1305, CPU 103 determines whether the current sheet has a blank side, that is, whether at least one of the front and back sides is blank. If the current sheet has a blank side (YES in step S1305), the process proceeds to step S1306; otherwise, the process proceeds to step S1307.

[0146] In step S1306, CPU 103 skips the blank side of the current sheet, that is, excludes it from the printing target, and proceeds to step S1307.

[0147] In step S1307, CPU 103 determines whether the current sheet has a non-blank side, that is, whether at least one of the front and back sides is a non-blank side (a side that is not blank). If the current sheet has a non-blank side (YES in step S1307), the process proceeds to step S1308; otherwise, the process proceeds to step S1316.

[0148] In step S1308, CPU 103 adds the non-blank sides of the current sheet to the pages to be printed, and proceeds to step S1311.

[0149] In step S1304, CPU 103 determines whether both the front and back sides of the current sheet are non-blank. If both the front and back sides are non-blank (YES in step S1304), the process proceeds to step S1309. If not (at least one of the front and back sides of the current sheet is blank), the process proceeds to step S1313.

[0150] In step S1309, CPU 103 calculates the total number of pages to be printed up to the sheet immediately preceding the current sheet, and proceeds to step S1310. However, if the current sheet is the first sheet, there is no sheet before that, so the total number of pages to be printed up to the sheet immediately preceding the current sheet is treated as "0" (zero).

[0151] In step S1310, CPU 103 determines whether the total number of pages to be printed calculated in step S1309 is an odd number. If it is an odd number (YES in step S1310), the process proceeds to step S1311. If it is not (an even number), the process proceeds to step S1312.

[0152] In step S1311, CPU 103 inserts a blank page to be printed immediately before the front side of the current sheet, and proceeds to step S1312.

[0153] In step S1312, CPU 103 adds the non-blank sides of the current sheet to the pages to be printed, and proceeds to step S1316.

[0154] In step S1313, CPU 103 skips the blank side of the current sheet, and advances the process to step S1314.

[0155] In step S1314, CPU 103 determines whether the current sheet has a non-blank side, that is, whether at least one of the front and back sides is a non-blank side (a side that is not blank). If the current sheet has a non-blank side (YES in step S1314), the process proceeds to step S1315; otherwise, the process proceeds to step S1316.

[0156] In step S1315, CPU 103 adds the non-blank sides of the current sheet to the pages to be printed, and proceeds to step S1316.

[0157] In step S1316, CPU 103 determines whether or not there is a next original sheet. If there is a next original sheet (YES in step S1316), the process returns to step S1301; otherwise, the subroutine in FIG.

[0158] 13, the process is switched depending on whether the total number of pages to be printed up to the sheet immediately preceding the current sheet is an odd number, but the control method in the present invention is not limited to this method. For example, the same determination may be made using the number of sheets up to the sheet immediately preceding the current sheet and information on the number of pages skipped, or the number of pages read and the number of pages skipped.

[0159] Fig. 14 is a table showing a list of blank page skip determination conditions in the single-sided / double-sided original mixed mode in the blank page skip reading process of Fig. 13. As shown in Fig. 14, in this embodiment, there are conditions 1 to 3 in the single-sided / double-sided original mixed mode.

[0160] Next, using Figures 15 and 16, a specific example will be described in which the blank skip reading process in the mixed single-sided / double-sided original mode in this embodiment is executed by reading a stack of originals that is a mixture of single-sided and double-sided originals from the ADF.

[0161] FIG. 15 is a schematic diagram showing a case where the blank page skip reading process in the mixed single-sided / double-sided original mode in this embodiment is performed on an original stack consisting of a stack of three single-sided originals on the upper side and a stack of two double-sided originals on the lower side.

[0162] As shown in FIG. 15(A), the back side of all three single-sided originals is blank, and both double-sided originals have print information (contents) on the front and back sides. When these originals are read, including the blank sides, the read image data shown in FIG. 15(B) is generated. Therefore, in this case, when the blank skip read process of FIG. 13 is performed with the single-sided / double-sided original mixed mode ON, the blank sides W1, W2, and W3 are skipped as shown in FIG. 15(C). Specifically, the blank sides W1, W2, and W3 are all skipped according to the application of condition 1 in FIG. 14, and condition 2 in FIG. 14 is applied, and a blank page Wadd to be printed is inserted before the front side (D1F) of the first sheet of the double-sided original. The result of double-sided printing of the read image data of the page configuration after the blank skip read process is shown in FIG. 15(D). That is, the first and second output sheets are the results of double-sided printing of the single-sided original, and the third and fourth output sheets are the results of double-sided printing of the double-sided original. In this way, the print results can be sorted by original document.

[0163] FIG. 16 is a schematic diagram showing a case where blank skip reading processing in the mixed single-sided / double-sided original mode in this embodiment is performed on an original stack consisting of a stack of four single-sided originals on the upper side and a stack of two double-sided originals on the lower side.

[0164] As shown in FIG. 16(A), all four single-sided originals have blank pages on the back, and both double-sided originals have print information (contents) on the front and back. When these originals are read, including the blank pages, the read image data shown in FIG. 16(B) is generated. Therefore, in this case, when the blank page skip read process of FIG. 13 is performed with the single-sided / double-sided original mixed mode ON, condition 1 of FIG. 14 is applied, and blank pages W1, W2, W3, and W4 are skipped as shown in FIG. 16(C). Condition 3 of FIG. 14 is applied, and a blank page Wadd to be printed is not inserted before the front (D1F) of the first sheet of the double-sided original. The result of double-sided printing of the read image data of the page configuration after the blank page skip is shown in FIG. 16(D), and the first and second output sheets are the results of double-sided printing of the single-sided original, and the third and fourth output sheets are the results of double-sided printing of the double-sided original. In this way, the print results can be sorted by the original original.

[0165] As described above, according to this embodiment, when the single-sided / double-sided original mixed mode is ON, blank pages are appropriately skipped or inserted when the single-sided original stack and the double-sided original stack in the original tray are read by the ADF during blank page removal + "double-sided to double-sided" copying. Therefore, the print target is set so that the back side of the sheet on which the last page of the single-sided original is printed in the output of the double-sided printing of the original stack is blank, and the print results can be sorted by original original. Note that images of both sides of the original stack in the original tray may be scanned first. As a result, if it is determined that the single-sided original stack is an odd number of sheets, a warning may be issued before setting the print target to the effect that it will be impossible to output sorted by original original if all blank pages detected in processing blocks 409 and 419 are excluded from the print target.

[0166] (Other embodiments) In this embodiment, a program for implementing one or more functions may be provided to a computer of the system or device via a network or storage medium, and the system controller of the system or device may read and execute the program. The system controller may have one or more processors or circuits, and may include multiple separate system controllers or a network of multiple separate processors or circuits to read and execute the executable instructions.

[0167] The processor or circuitry may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU).

[0168] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0169] The disclosure of this embodiment includes the following configuration, method, and program. (Configuration 1) An image forming apparatus including an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a second side, which is the other side of the separated and conveyed document sheets, a printing unit capable of double-sided printing, and a blank paper detection unit that detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit. and when the original stack is a stack of originals with a single-sided original on the upper side and a double-sided original on the lower side, the setting means sequentially reads image data of the first and second sides of the separated and transported original sheets by the reading unit, performs blank page skip determination as to whether or not the blank sides detected by the blank page detection unit are to be excluded from the printing target, and sets the printing target to be double-sided printed by the printing unit from the image data sequentially read in accordance with the result of the blank page skip determination, and the setting means is configured to an image forming apparatus comprising: an image forming unit that, when only one of the first and second sides of a first original sheet is detected as a blank side by the blank page detection unit and the total number of pages to be printed from the first sheet of the original stack to the sheet immediately preceding the first original sheet is an even number, suspends the blank page skip judgment for the first original sheet until a subsequent second original sheet appears, wherein at least one of the first and second sides of the second original sheet is detected as a blank side by the blank page detection unit, determines in the blank page skip judgment that the blank side of the first original sheet should be excluded from the printing target, and adds the non-blank side of the first original sheet to the printing target; and, when both the first and second sides of the second original sheet are detected as non-blank sides by the blank page detection unit, determines in the blank page skip judgment that the blank side of the first original sheet should not be excluded from the printing target, and adds both the blank side and the non-blank side of the first original sheet to the printing target. (Configuration 2) The image forming apparatus according to configuration 1, characterized in that when only one of the first and second sides of the first manuscript sheet is detected as a blank side and the total number of pages to be printed from the first sheet of the manuscript stack to the sheet immediately preceding the first manuscript sheet is an odd number, the setting means determines in the blank skip determination to exclude the blank side of the first manuscript sheet from the pages to be printed, and adds the non-blank side of the first manuscript sheet to the pages to be printed. (Configuration 3) The image forming apparatus according to configuration 1 or 2, wherein the setting means determines in the blank skip determination that the first and second sides of the first manuscript sheet are to be excluded from printing when both the first and second sides of the first manuscript sheet are blank. (Configuration 4) An image forming apparatus comprising: an automatic document feeder which separates and conveys document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a second side, which is the other side of the separated and conveyed document sheets; a printing unit capable of double-sided printing; and a blank paper detection unit which detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit, When the document stack is a mixture of a single-sided document stack on the upper side and a double-sided document stack on the lower side, the image data of the first and second sides of the separated and transported document sheets are sequentially read by the reading unit, a blank page skip determination is performed as to whether or not the blank page detected by the blank page detection unit should be excluded from the printing target, and a setting unit is provided for setting a printing target to be double-sided printed by the printing unit from the sequentially read image data according to the result of the blank page skip determination, and the setting unit is configured to set the first and second sides of the separated and transported document sheets by the reading unit. When at least one of the first and second sides is detected as a blank side by the blank page detection unit, the blank page skip determination determines that the blank side of the first original sheet is to be excluded from the printing target, and when the first original sheet has a non-blank side, the non-blank side is added to the printing target, and when the blank page detection unit detects that both the first and second sides of the first original sheet are non-blank sides and the total number of pages to be printed from the top sheet of the original stack to the sheet immediately preceding the first original sheet is an odd number, an image forming apparatus comprising: inserting a blank page to be printed immediately before the first side of a first manuscript sheet; adding the non-blank side of the first manuscript sheet to the pages to be printed; and, when the blank page detection unit detects that both the first and second sides of the first manuscript sheet are non-blank sides and the total number of pages to be printed from the first sheet of the manuscript stack to the sheet immediately before the first manuscript sheet is an even number, adding the non-blank side of the first manuscript sheet to the pages to be printed without inserting the blank page to be printed. (Configuration 5) The image forming apparatus according to any one of configurations 1 to 3, further comprising a switching means for switching, by a user operation, between a first setting in which the document stack is the mixed document stack and a second setting in which the document stack is not the mixed document stack, wherein the setting means sets the printing target when the setting is switched to the first setting by the switching means, and when the setting is switched to the second setting by the switching means, determines in the blank paper skip determination that all sides of the separated and transported document sheets that are detected as blank sides by the blank paper detection unit are to be excluded from the printing target. (Configuration 6) The image forming apparatus according to Configuration 5, further comprising a dedicated button which, when pressed by a user, switches to the first setting, and starts double-sided printing in the printing unit after setting the printing target in the setting means. (Configuration 7) The image forming apparatus according to Configuration 4, further comprising a switching means for switching, by a user operation, between a first setting in which the document stack is the mixed document stack and a second setting in which the document stack is not the mixed document stack, wherein the setting means sets the printing target when the switching means has switched to the first setting, and when the switching means has switched to the second setting, the setting means determines in the blank paper skip determination that all sides of the separated and transported document sheets that are detected as blank sides by the blank paper detection unit are to be excluded from the printing target. (Configuration 8) The image forming apparatus according to Configuration 7, further comprising a dedicated button which, when pressed by a user, switches to the first setting, and starts double-sided printing in the printing unit after setting the printing target in the setting means. (Configuration 9) The image forming apparatus according to any one of configurations 1 to 3, wherein the blank page detection unit detects whether a page is blank or non-blank according to a variance calculated from a frequency distribution consisting of pixel values ​​of the image data and their frequencies and a threshold value for the variance, and the value of the threshold value is set according to a blank page detection level that can be changed by the user. (Configuration 10) The image forming apparatus according to configuration 4, wherein the blank page detection unit detects whether a page is blank or non-blank according to a variance calculated from a frequency distribution consisting of pixel values ​​of the image data and their frequencies and a threshold value for the variance, and the value of the threshold value is set according to a blank page detection level that can be changed by the user. (Configuration 11) An image forming device comprising an automatic document feeder which separates and transports document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and transported document sheets, and a second side, which is the other side of the separated and transported document sheets, a printing unit capable of double-sided printing, and a blank paper detection unit which detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit, wherein when the document stack is a mixture of a stack of single-sided documents on the upper side and a stack of double-sided documents on the lower side, an image forming apparatus including a setting means for sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, performing a blank page skip determination as to whether or not to exclude the blank sides detected by the blank page detection unit from the printing target, and setting the printing target to be double-sided printed by the printing unit from the image data read sequentially in accordance with the result of the blank page skip determination, wherein when the stack of single-sided originals is an odd number of sheets, the setting means sets the printing target so that the back side of the sheet on which the last page of the single-sided originals is printed in the output of the double-sided printing of the stack of originals by the printing unit will be blank. (Configuration 12) The image forming apparatus according to configuration 11, wherein the setting means, when it is determined that the stack of single-sided documents contains an odd number of sheets as a result of the reading unit sequentially reading both sides of the document sheets of the document stack, further includes a notification means for issuing a warning that if all blank sides detected by the blank page detection unit are excluded from the printing target before setting the printing target, it will be impossible to output documents sorted by original documents. (Method 1) A control method for an image forming device including an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a second side, which is the other side of the separated and conveyed document sheets, a printing unit capable of double-sided printing, and a blank paper detection unit that detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit, When the original stack is a mixture of an upper bundle of single-sided originals and a lower bundle of double-sided originals, the method further comprises a setting step of sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, performing a blank page skip determination as to whether or not to exclude a blank page detected by the blank page detection unit from a printing target, and setting a printing target to be double-sided printed by the printing unit from the sequentially read image data according to a result of the blank page skip determination, the setting step including: a first step of suspending the blank skip determination for the first original sheet until a subsequent second original sheet appears, the subsequent second original sheet having at least one of the first and second sides not being blank, when only one of the first and second sides is detected as a blank side by the blank detection unit and the total number of pages to be printed from the leading sheet of the original stack to the sheet immediately preceding the first original sheet is an even number; a second step of determining in the blank page skip determination that the blank side of the first manuscript sheet should be excluded from the printing target and adding a non-blank side of the first manuscript sheet to the printing target when the blank page detection unit detects that both the first and second sides of the second manuscript sheet are non-blank sides by the blank page detection unit, and a second step of determining in the blank page skip determination that the blank side of the first manuscript sheet should not be excluded from the printing target and adding both the blank side and non-blank side of the first manuscript sheet to the printing target when the blank page detection unit detects that both the first and second sides of the second manuscript sheet are non-blank sides by the blank page detection unit. (Method 2) A control method for an image forming apparatus including an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a second side, which is the other side of the separated and conveyed document sheets, a printing unit capable of double-sided printing, and a blank paper detection unit that detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit, wherein the document stack is When the original bundle is a mixture of a single-sided original bundle on the upper side and a double-sided original bundle on the lower side, the method further comprises a setting step of sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, performing a blank page skip determination as to whether or not to exclude a blank page detected by the blank page detection unit from a printing target, and setting a printing target to be double-sided printed by the printing unit from the sequentially read image data according to a result of the blank page skip determination, the setting step being performed by performing a setting step of at least one of the first and second sides of a first original sheet separated and transported from the original bundle. a first step of determining in the blank page skip determination that the blank side of the first original sheet is to be excluded from the printing target when at least one of the first and second sides of the first original sheet is detected by the blank page detection unit to be a blank side, and adding the non-blank side to the printing target when the first original sheet has a non-blank side; and a second step of determining in the blank page skip determination that the blank side of the first original sheet is to be excluded from the printing target when the blank page detection unit detects that both the first and second sides of the first original sheet are non-blank sides and the total number of pages to be printed from the top sheet of the original stack to the sheet immediately preceding the first original sheet is an odd number. a second step of inserting a blank page to be printed immediately before a first side and adding the non-blank side of the first manuscript sheet to the pages to be printed; and a third step of adding the non-blank side of the first manuscript sheet to the pages to be printed without inserting the blank page to be printed when the blank page detection unit detects that both the first and second sides of the first manuscript sheet are non-blank sides and the total number of pages to be printed from the first sheet of the manuscript stack to the sheet immediately before the first manuscript sheet is an even number. (Method 3) A control method for an image forming device including an automatic document feeder that separates and conveys document sheets one by one from the top of a document stack placed on a document tray, a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed document sheets, and a second side, which is the other side of the separated and conveyed document sheets, a printing unit capable of double-sided printing, and a blank paper detection unit that detects whether the first side is a blank or non-blank side and whether the second side is a blank or non-blank side based on the image data of the first and second sides read by the reading unit, wherein the document stack is a mixture of a single-sided document stack on the top and a double-sided document stack on the bottom. a setting step of sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, performing a blank page skip determination as to whether or not to exclude the blank side detected by the blank page detection unit from the printing target, and setting the printing target to be double-sided printed by the printing unit from the sequentially read image data in accordance with the result of the blank page skip determination, wherein the setting step sets the printing target so that, when the stack of single-sided originals is an odd number of sheets, the back side of the sheet on which the last page of the single-sided originals is printed in the output of the double-sided printing of the stack of originals by the printing unit will be blank. (Program 1) A program for causing a computer to function as each of the means of the image forming apparatus described in any one of configurations 1 to 3, 5, 6, and 9. (Program 2) A program for causing a computer to function as each of the means of the image forming apparatus described in configurations 4, 7, 8, and 10. (Program 3) A program for causing a computer to function as each of the means of the image forming apparatus described in configurations 11 and 12. [Explanation of symbols]

[0170] 101 Image forming device 103 CPU 105 RAM 109 Scanner I / F 112 Operation section 113 Printer 114 Scanner 116 Scanner image processing unit 409,419 Processing Blocks

Claims

1. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; An image forming apparatus comprising: a setting means for setting a print target to be printed on both sides by the printing unit from the image data read sequentially when the original stack is an original stack having a single-sided original stack on the upper side and a double-sided original stack on the lower side, the setting means sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, making a blank page skip determination as to whether or not a blank page detected by the blank page detection unit should be excluded from a print target, and setting a print target to be printed on both sides by the printing unit from the image data read sequentially according to a result of the blank page skip determination, The setting means is when only one of the first and second sides of a first original sheet separated and conveyed from the original stack is detected as a blank surface by the blank detection unit, and the total number of pages to be printed from the leading sheet of the original stack to the sheet immediately preceding the first original sheet is an even number, the blank skip determination for the first original sheet is suspended until a subsequent second original sheet appears, at least one of the first and second sides of which is not a blank surface; When either one of the first and second sides of the second original sheet is detected as a blank side by the blank page detection unit, the blank page skip determination determines that the blank side of the first original sheet is to be excluded from the printing target, and adds the non-blank side of the first original sheet to the printing target; An image forming apparatus characterized in that, when both the first and second sides of the second original sheet are detected to be non-blank sides by the blank page detection unit, the blank page skip determination determines that the blank side of the first original sheet will not be excluded from the printing target, and both the blank side and the non-blank side of the first original sheet are added to the printing target.

2. The setting means is The image forming apparatus according to claim 1, characterized in that when only one of the first and second sides of the first original sheet is detected as a blank side and the total number of pages to be printed from the first sheet of the original stack to the sheet immediately preceding the first original sheet is an odd number, the blank skip determination determines that the blank side of the first original sheet should be excluded from the printing target, and the non-blank side of the first original sheet is added to the printing target.

3. The setting means is 2. The image forming apparatus according to claim 1, characterized in that, when the first and second sides of the first manuscript sheet are both blank, the blank skip determination determines that the first and second sides of the first manuscript sheet are to be excluded from printing.

4. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; An image forming apparatus comprising: a setting means for setting a print target to be printed on both sides by the printing unit from the image data read sequentially when the original stack is an original stack having a single-sided original stack on the upper side and a double-sided original stack on the lower side, the setting means sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, making a blank page skip determination as to whether or not a blank page detected by the blank page detection unit should be excluded from a print target, and setting a print target to be printed on both sides by the printing unit from the image data read sequentially according to a result of the blank page skip determination, The setting means is when at least one of the first and second sides of a first original sheet separated and conveyed from the original stack is detected as a blank side by the blank page detection unit, it is determined in the blank page skip determination that the blank side of the first original sheet is to be excluded from the printing target, and when the first original sheet has a non-blank side, the non-blank side is added to the printing target; when the blank page detection unit detects that both the first and second sides of the first original sheet are non-blank sides and the total number of pages to be printed from the leading sheet of the original stack to the sheet immediately preceding the first original sheet is an odd number, inserting a blank page to be printed immediately preceding the first side of the first original sheet, and adding the non-blank side of the first original sheet to the pages to be printed; An image forming apparatus characterized in that, when the blank page detection unit detects that both the first and second sides of the first original sheet are non-blank sides, and when the total number of pages to be printed from the first sheet of the original stack to the sheet immediately preceding the first original sheet is an even number, the non-blank side of the first original sheet is added to the pages to be printed without inserting a blank page to be printed.

5. a switching unit that switches the document stack between a first setting for treating the document stack as the mixed document stack and a second setting for treating the document stack as not being the mixed document stack by a user operation; The setting means is When the setting is changed to the first setting by the switching means, the setting of the printing target is performed; 2. The image forming apparatus according to claim 1, wherein when the switching means has switched to the second setting, the blank page skip determination determines that all sides of the separated and transported original sheet that are detected as blank by the blank page detection unit are to be excluded from printing.

6. 6. The image forming apparatus according to claim 5, further comprising a dedicated button which, when pressed by a user, switches to the first setting, and starts double-sided printing in the printing unit after the printing target is set in the setting unit.

7. a switching unit that switches the document stack between a first setting for treating the document stack as the mixed document stack and a second setting for treating the document stack as not being the mixed document stack by a user operation; The setting means is When the setting is changed to the first setting by the switching means, the setting of the printing target is performed; 5. The image forming apparatus according to claim 4, characterized in that, when the switching means has switched to the second setting, the blank paper skip determination determines that all sides of the separated and transported original sheet that are detected as blank by the blank paper detection unit are to be excluded from printing.

8. 8. The image forming apparatus according to claim 7, further comprising a dedicated button which, when pressed by a user, switches to the first setting, and starts double-sided printing in the printing unit after the printing target is set in the setting unit.

9. The blank page detection unit A blank or non-blank surface is detected according to a variance calculated from a frequency distribution consisting of pixel values ​​and their frequencies of the image data and a threshold value thereof; 2. The image forming apparatus according to claim 1, wherein the threshold value is set according to a blank paper detection level that can be changed by the user.

10. The blank page detection unit A blank or non-blank surface is detected according to a variance calculated from a frequency distribution consisting of pixel values ​​and their frequencies of the image data and a threshold value thereof; 5. The image forming apparatus according to claim 4, wherein the threshold value is set according to a blank paper detection level that can be changed by the user.

11. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; An image forming apparatus comprising: a setting means for setting a print target to be printed on both sides by the printing unit from the image data read sequentially when the original stack is an original stack having a single-sided original stack on the upper side and a double-sided original stack on the lower side, the setting means sequentially reading image data of the first and second sides of the separated and transported original sheets by the reading unit, making a blank page skip determination as to whether or not a blank page detected by the blank page detection unit should be excluded from a print target, and setting a print target to be printed on both sides by the printing unit from the image data read sequentially according to a result of the blank page skip determination, The image forming device is characterized in that, when the stack of single-sided originals contains an odd number of sheets, the setting means sets the printing target so that the back side of the sheet on which the last page of the single-sided original is printed in the output of double-sided printing of the stack of originals by the printing unit will be blank.

12. The image forming apparatus according to claim 11, characterized in that the setting means, when it is determined that the stack of single-sided documents contains an odd number of sheets as a result of the reading unit sequentially reading both sides of the document sheets of the document stack, further includes a notification means for issuing a warning that if all blank sides detected by the blank page detection unit are excluded from the printing target before setting the printing target, it will be impossible to output the documents sorted by original documents.

13. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; A control method for an image forming apparatus comprising: a setting step of, when the original stack is a stack of originals with one-sided originals on the upper side and two-sided originals on the lower side, reading image data of the first and second sides of the separated and transported original sheets sequentially by the reading unit, making a blank page skip determination as to whether or not the blank page detected by the blank page detection unit should be excluded from the printing target, and setting a printing target to be double-sided printed by the printing unit from the image data read sequentially according to the result of the blank page skip determination; The setting step includes: a first step of suspending the blank skip determination for the first original sheet until a subsequent second original sheet appears, when only one of the first and second sides of a first original sheet separated and conveyed from the original stack is detected as a blank surface by the blank detection unit and the total number of pages to be printed from the leading sheet of the original stack to the sheet immediately preceding the first original sheet is an even number; a second step of determining, when either one of the first and second sides of the second original sheet is detected as a blank side by the blank page detection unit, that the blank side of the first original sheet is to be excluded from a printing target in the blank page skip determination, and adding a non-blank side of the first original sheet to the printing target; and a second step of, when the first and second sides of the second original sheet are both detected as non-blank sides by the blank page detection unit, determining in the blank page skip determination that the blank side of the first original sheet will not be excluded from the printing target, and adding both the blank side and the non-blank side of the first original sheet to the printing target.

14. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; A control method for an image forming apparatus comprising: a setting step of, when the original stack is a stack of originals with one-sided originals on the upper side and two-sided originals on the lower side, reading image data of the first and second sides of the separated and transported original sheets sequentially by the reading unit, making a blank page skip determination as to whether or not the blank page detected by the blank page detection unit should be excluded from the printing target, and setting a printing target to be double-sided printed by the printing unit from the image data read sequentially according to the result of the blank page skip determination; The setting step includes: a first step of determining, when at least one of the first and second sides of a first original sheet separated and conveyed from the original stack is detected as a blank side by the blank page detection unit, that the blank side of the first original sheet is to be excluded from a printing target in the blank page skip determination, and, when the first original sheet has a non-blank side, adding the non-blank side to the printing target; a second step of inserting a blank page to be printed immediately before the first side of the first document sheet and adding the non-blank side of the first document sheet to the pages to be printed when the blank page detection unit detects that both the first and second sides of the first document sheet are non-blank sides and when a total number of pages to be printed from the leading sheet of the document stack to the sheet immediately before the first document sheet is an odd number; and a third step of adding the non-blank sides of the first manuscript sheet to the pages to be printed without inserting a blank page to be printed when the blank page detection unit detects that both the first and second sides of the first manuscript sheet are non-blank sides and when the total number of pages to be printed from the first sheet of the manuscript stack to the sheet immediately preceding the first manuscript sheet is an even number.

15. an automatic document feeder that separates and feeds document sheets one by one from the top of a document stack placed on a document tray; a reading unit capable of reading image data of a first side, which is one side of the separated and conveyed original sheet, and a second side, which is the other side of the separated and conveyed original sheet; A printing section capable of double-sided printing; a blank page detection unit that detects whether the first side is a blank page or a non-blank page and detects whether the second side is a blank page or a non-blank page based on image data of the first and second sides read by the reading unit; A control method for an image forming apparatus comprising: a setting step of, when the original stack is a stack of originals with one-sided originals on the upper side and two-sided originals on the lower side, reading image data of the first and second sides of the separated and transported original sheets sequentially by the reading unit, making a blank page skip determination as to whether or not the blank page detected by the blank page detection unit should be excluded from the printing target, and setting a printing target to be double-sided printed by the printing unit from the image data read sequentially according to the result of the blank page skip determination; The control method is characterized in that, in the setting step, when the stack of single-sided originals contains an odd number of sheets, the printing target is set so that the back side of the sheet on which the last page of the single-sided original is printed in the output of double-sided printing of the stack of originals by the printing unit is blank.

16. A program for causing a computer to function as each of the means of the image forming apparatus according to claim 1.

17. A program for causing a computer to function as each of the means of the image forming apparatus according to claim 4.

18. A program for causing a computer to function as each of the means of the image forming apparatus according to claim 11.

Images