JP6163907B2 - Image reading apparatus, image forming apparatus, and program - Google Patents

Description

  The present invention relates to an image reading apparatus, an image forming apparatus, and a program.

  In an image reading apparatus that reads an image from a document, a technique for correcting the inclination of the read image is known. Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for detecting the tilt of an image from image data obtained by optically reading a document and correcting the image data based on the detected tilt. Patent Document 2 describes a technique for detecting a skew angle of a scanned image based on the outer shape of a page extracted from the scanned image, and correcting distortion on the scanned image according to the detected skew angle. . Patent Document 3 describes that it is determined whether or not a manuscript has been tilted by the user, and the tilt of the image caused by the user is not corrected.

JP-A-8-251387 JP 2003-189082 A JP 2010-011360 A

  An object of the present invention is to shorten the time from when an image of a document is read to when correction of the inclination of the image is started.

The image reading apparatus according to claim 1, reading means for reading an image from a document, and a conveying means for sequentially conveying a plurality of originals to said reading means, storage means for storing the tilt of the images, the reading unit detecting means for the inclination of the image of the document read, and correcting means for correcting, based on the inclination stored in the storage means, in parallel with the correction by the correcting means, for detecting a tilt of the image of the document by And the inclination stored in the storage means is detected by the detection means if the difference between the inclination stored in the storage means and the inclination detected by the detection means exceeds a first threshold. possess an updating means for updating the inclination, the correction means, when the slope stored in said memory means is updated by said updating means, to interrupt the correction of the running, based on the tilt of the updated The The inclination of the image of the original is corrected, and when the next original of the original is read, the inclination of the image of the next original read by the reading unit is corrected based on the inclination stored in the storage unit. It is characterized by doing .

The image reading apparatus according to claim 2 is the structure of claim 1, when the inclination detected by pre Symbol detection means satisfy the determined condition, the update unit, the difference is the first threshold value Regardless of whether or not the value exceeds the inclination, the inclination stored in the storage means is updated to the inclination detected by the detection means, and the correction means updates the inclination stored in the storage means by the update means. The correction is started after the update.

Read image according to claim 3 devices, in the configuration of claim 2, prior SL-determined conditions, the frequency of the difference exceeds the first threshold value, that exceeds a frequency which is determined It is characterized by being.

4. The image reading apparatus according is characterized in that in the configuration of claim 2, prior SL-determined condition is that the difference exceeds a second threshold value larger than the first threshold value And

The image forming apparatus according claim 5, reading means for reading an image from the original draft, and conveying means for sequentially conveying a plurality of originals to said reading means, storage means for storing the tilt of the images, the reading unit detecting means for the inclination of the image of the document read, and correcting means for correcting, based on the inclination stored in the storage means, in parallel with the correction by the correcting means, for detecting a tilt of the image of the document by And the inclination stored in the storage means is detected by the detection means if the difference between the inclination stored in the storage means and the inclination detected by the detection means exceeds a first threshold. and updating means for updating the inclination, the image inclination is corrected by the correction means, have a image forming means for forming on a recording medium, the correction means, the slope stored in said storing means the update If it is updated by a stage, the correction that is being executed is interrupted, the inclination of the image of the original is corrected based on the updated inclination, and is read by the reading unit when the next original of the original is read. The inclination of the image of the next original is corrected based on the inclination stored in the storage means .

According to a sixth aspect of the present invention, there is provided a program including a reading unit, a conveying unit, a storage unit, and a control unit, wherein the reading unit reads an image from a document, and the conveying unit includes a plurality of units for the reading unit. A step of sequentially transporting the original, a step in which the storage means stores an inclination of an image read from the original, and a control means in which the inclination of the image of the original read by the reading means is stored in the storage means. The step of correcting based on the inclination stored in the step, the step of the control means detecting the inclination of the image of the document in parallel with the step of correcting, and the inclination stored in the storage means If the difference between the detected slope is greater than a first threshold value, said control means interrupts the correction of the running, the inclination stored in the storage means the Based on the slope after being updated in the issued inclination correcting the tilt of the image of the document, the inclination of the next document image of the document read by said reading means, on the basis of the inclination of the updated And a step of correcting.

According to the first, fifth , and sixth aspects of the invention, the image of the second original is compared with the case where the correction of the inclination of the image is started after the inclination of the image of the second original is detected. The time from reading to the start of correction of the tilt of the image is shortened.
According to the invention of claim 2, when satisfying the condition that the inclination of the image of the second original has been determined, error when the inclination of the image of the second original is corrected is reduced.
According to the invention according to claim 3, when the difference between the inclination of the image of the first document and the inclination of the image of the second document exceeds the first threshold, An error in correcting the inclination of the image of the second original is reduced.
According to the fourth aspect of the present invention, when the difference between the inclination of the image of the first original and the inclination of the image of the second original exceeds a second threshold that is larger than the first threshold, the second The error when the inclination of the original image is corrected is reduced.

Block diagram showing the functional configuration of the image forming apparatus Block diagram showing hardware configuration of image forming apparatus The figure explaining the whole structure of an image reading part Flow chart showing processing for reading image Diagram illustrating update of reference slope α Timing chart showing the relationship between image reading and image data output Timing chart showing another example of relationship between image reading and image data output

  FIG. 1 is a block diagram showing a functional configuration of an image forming apparatus 1000 according to an embodiment of the present invention. The image forming apparatus 1000 is an apparatus that functions as a copier, a printer, a scanner, a facsimile, or the like. The image forming apparatus 1000 includes a document conveying unit 11, an image reading unit 12, a storage unit 13, a correcting unit 14, a detecting unit 15, an updating unit 16, and an image forming unit 17. The document transport unit 11 sequentially transports a plurality of documents to the image reading unit 12 in units of pages. The image reading unit 12 reads an image from a document. In the following, among the plurality of originals, the original read by the image reading unit 12 first is expressed as “first original”, and the original read by the image reading unit 12 after the first original is “ This is expressed as “second manuscript”. Here, the term “original” refers to one of the documents recorded on a plurality of sheets. The storage unit 13 stores an inclination used in inclination correction described later. Hereinafter, the inclination stored in the storage unit 13 is expressed as “reference inclination”. The correcting unit 14 corrects the inclination of the document image based on the reference inclination. The detection unit 15 detects the inclination of the image of the second document in parallel with the correction by the correction unit 14. The update means 16 updates the reference inclination to the inclination detected by the detection means 15 when the difference between the reference inclination and the inclination of the second original image detected by the detection means 15 exceeds the first threshold. . The first threshold value is a predetermined value that serves as a reference when the reference slope is updated by the update unit 16. The image forming unit 17 forms an image whose inclination is corrected by the correcting unit 14 on a sheet (an example of a recording medium).

  FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus 1000. The image forming apparatus 1000 includes a control unit 101, a communication unit 102, a storage unit 103, a display unit 104, an input unit 105, an image reading unit 106, and an image forming unit 107. The control unit 101 controls the operation of each unit of the image forming apparatus 1000. The control unit 101 includes a CPU (Central Processing Unit) 1011, a ROM (Read Only Memory) 1012, and a RAM (Random Access Memory) 1013. The CPU 1011 is a control device that controls each unit of the image forming apparatus 1000 by executing a program. The ROM 1012 is a non-volatile storage device that stores various programs and data. The RAM 1013 is a volatile storage device that stores data. In the present embodiment, the RAM 1013 has a storage area (frame memory) that stores image data for one sheet of document read by the image reading unit 106. The communication unit 102 communicates with an external device. The storage unit 103 is a storage device that stores data and programs, for example, an HDD. The display unit 104 includes a display device such as a liquid crystal display or an organic EL display, and displays a menu screen or various messages for operating the image forming apparatus 1000. The input unit 105 includes various keys for inputting data or instructions to the image forming apparatus 1000. The input unit 105 also includes a touch screen (touch panel) provided on the display of the display unit 104. The image reading unit 106 is an image scanner that optically reads a document and outputs image data indicating the read document. The image forming unit 107 is an apparatus that forms an image on a sheet by, for example, an electrophotographic method or an inkjet method.

  FIG. 3 is a diagram illustrating the overall configuration of the image reading unit 106. The image reading unit 106 includes a container 1061, a delivery roll 111, a first feed roll 112, a pre-registration roll 113, a registration roll 114, a platen glass 1062, a full rate carriage 121, a half rate carriage 122, and a second feed. A roll 115, an out-roll 116, an imaging lens 123, a CCD (Charge Coupled Device) image sensor 124, and a storage unit 1063 are included.

  The container 1061 loads a plurality of documents. An image such as a photograph, a character, or a line drawing is recorded on the original loaded on the container 1061. The delivery roll 111 is lifted up and held at the retracted position during standby, and is lowered to the nip position (original conveyance position) during document conveyance. The delivery roll 111 lowered to the nip position picks up the uppermost document one by one from the bundle of documents loaded on the container 1061 and conveys it downstream. In the following, the direction in which the document is conveyed is expressed as a “conveyance direction”. The first feed roll 112 transports the document transported by the delivery roll 111 further downstream in the transport direction. The pre-registration roll 113 transports the document to a roll further downstream in the transport direction and forms a loop (deflection) of the document. Specifically, the pre-registration roll 113 forms a loop on the document by abutting the leading edge of the document against the stopped registration roll 114. The registration roll 114 once stops and resumes rotation at the same timing, and conveys the original while performing registration adjustment on the area of the platen glass 1062 where the original is read. The document conveyed from the registration roll 114 is pressed against the platen glass 1062. In the following, the surface of the document that comes into contact with the platen glass 1062 when pressed is expressed as “front surface”.

  The full rate carriage 121 includes a lamp 121L and a first mirror M1. The lamp 121L is a rod-shaped light source extending in the main scanning direction (a direction perpendicular to the paper surface of FIG. 3), and irradiates light on the surface of the document pressed against the platen glass 1062. Hereinafter, an area on the platen glass 1062 that is irradiated with light by the lamp 121L (that is, an area where an original is read) is expressed as a “read line”. The first mirror M1 receives the reflected light of the light irradiated on the document. The half rate carriage 122 includes a second mirror M2 and a third mirror M3. The second mirror M2 and the third mirror M3 propagate the light obtained from the first mirror M1 to the imaging lens 123. The imaging lens 123 optically reduces the optical image obtained from the third mirror M3. The CCD image sensor 124 photoelectrically converts the optical image formed by the imaging lens 123. As a result, the images recorded on the surface of the document are read along the reading line in order from the downstream side in the transport direction.

  The second feed roll 115 conveys the document whose image has been read by the CCD image sensor 124 toward the out roll 116. The out roll 116 discharges the document toward the storage unit 1063. The accumulating unit 1063 accumulates the document discharged by the out-roll 116. The image reading unit 106 has a configuration for reading a document placed on the platen glass 1062 in addition to the document loaded on the container 1061. When reading an original placed on the platen glass 1062, the image reading unit 106 moves the full rate carriage 121 and the half rate carriage 122 in the direction of the arrow D1.

  In the image reading unit 106, the CPU 1011 executing the program is an example of the correction unit 14, the detection unit 15, and the update unit 16. A RAM 1013 controlled by the CPU 1011 executing the program is an example of the storage unit 13. The delivery roll 111, the first feed roll 112, the pre-registration roll 113, and the registration roll 114 controlled by the CPU 1011 executing the program are examples of the document conveying unit 11. The full-rate carriage 121, the half-rate carriage 122, the imaging lens 123, and the CCD image sensor 124 that are controlled by the CPU 1011 executing the program are examples of the image reading unit 12. The image forming unit 107 controlled by the CPU 1011 executing the program is an example of the image forming unit 17.

  FIG. 4 is a flowchart illustrating processing in which the image forming apparatus 1000 reads an image from a document. The following processing is started when, for example, the user inputs an image reading instruction to the image forming apparatus 1000 by operating the input unit 105 in a state where a plurality of documents are stacked on the container 1061. The An image reading instruction is input to execute a function such as copying, scanning, or facsimile. Note that “tilt” described below refers to the tilt of an image recorded on a document with respect to a reading line.

  In step S <b> 1, the CPU 1011 starts reading an image of the uppermost document among a plurality of documents stacked on the container 1061. In the following, a document that is a target of image reading is expressed as a “target document”. In addition, when the target document is a second or subsequent document, a document whose reading is started before the target document is expressed as “preceding document”. The image data of the target document is stored in the frame memory in order from the data on the downstream side in the transport direction.

  In step S2, the CPU 1011 determines whether or not the inclination of the image read from the preceding document satisfies a predetermined condition. As an example of the determined condition, a second threshold (hereinafter referred to as “threshold Th2”) in which the difference between the reference tilt and the tilt of the image of the preceding document is larger than a first threshold (hereinafter referred to as “threshold Th1”). It was over). As another example of the determined conditions, for a plurality of preceding documents, the frequency at which the difference between the reference tilt and the tilt of the image of the preceding document exceeds the threshold Th1 is input from the input unit 105 as an instruction to read an image. The frequency that was determined from the time of being exceeded was exceeded. In this case, in step S <b> 1, the CPU 1011 stores in the RAM 1013 the number of documents that have been read after an image reading instruction is input. The determination of the frequency may be performed after the number of originals from which reading has started exceeds a predetermined number. The element for determining whether or not the determined condition is satisfied is stored in the RAM 1013 when the determination in step S6 described later is “YES”. If it is determined that the inclination of the image read from the preceding document does not satisfy the determined condition (step S2: NO), the CPU 1011 shifts the processing to step S3. In the processing from step S3 to step S10, correction of the inclination of the image of the target document (hereinafter referred to as “tilt correction”) is started before the inclination of the image of the target document is detected. Hereinafter, the processing in steps S3 to S10 is expressed as “parallel processing mode”. When it is determined that the inclination of the image read from the preceding document satisfies the determined condition (step S2: YES), the CPU 1011 shifts the process to step S11. In the processing from step S11 to step S14, the inclination correction is started after the inclination of the image of the target document is detected. Hereinafter, the processing in steps S11 to S14 is expressed as “individual processing mode”. When the target document is the first document read (that is, when there is no preceding document), the CPU 1011 shifts to the parallel processing mode without making a determination in step S2.

  In step S <b> 3, the CPU 1011 starts inclination correction using a reference inclination (hereinafter referred to as “reference inclination α”) stored in the RAM 1013. Specifically, the CPU 1011 sequentially processes the image data of the target document stored in the frame memory in a predetermined processing unit (for example, one pixel or one line (a plurality of pixels in the main scanning direction) from the downstream data in the transport direction. For each pixel))), and tilt correction is started. The CPU 1011 performs tilt correction on the read processing unit data. The CPU 1011 stores the tilt-corrected data in the data storage area of the frame memory. In the following, the image data of the target document after the inclination correction is started is expressed as “image data being corrected”. Further, the image data of the target document before the tilt correction is started is expressed as “pre-correction image data”. Note that an initial value is set in advance for the reference inclination α and is stored in the ROM 1012. If the target document is the first scanned document, the CPU 1011 starts tilt correction using the initial value.

  In step S4, the CPU 1011 starts outputting the image data being corrected. Specifically, the CPU 1011 reads out the corrected image data from the frame memory in order from the data on the downstream side in the transport direction, and starts output to the image forming unit 107.

  In step S5, the CPU 1011 detects the inclination of the image of the target document (hereinafter referred to as “inclination β”). Specifically, the CPU 1011 receives a part of predetermined data (for example, data corresponding to several lines from the most downstream in the transport direction) from the frame memory from among the corrected image data among the corrected image data. It reads out and detects the inclination of the image indicated by the data (hereinafter referred to as “inclination γ”). The CPU 1011 detects the inclination β by calculating the sum of the detected inclination γ and the reference inclination α. The CPU 1011 stores the detected inclination β and inclination γ in the RAM 1013. The CPU 1011 reads from the frame memory data that has not yet been subjected to tilt correction among the image data being corrected (for example, reads data for several lines from the most upstream of the image data being corrected in the transport direction). ), The slope β may be detected. In this case, the CPU 1011 may detect the inclination γ by calculating the difference between the detected inclination β and the reference inclination α. As described above, the CPU 1011 detects the inclination β in parallel with the inclination correction of the image data of the target original, using the frame memory for one original. Here, “parallel” means that the detection of the inclination of the image of the target document is started after the correction of the inclination of the image data of the target document is started.

  In step S6, the CPU 1011 determines whether or not the difference between the reference inclination α and the inclination β exceeds the threshold value Th1. Specifically, the CPU 1011 reads the reference inclination α and inclination β from the RAM 1013 and the threshold value Th1 from the ROM 1012, and determines whether or not the absolute value of the difference between the reference inclination α and the inclination β exceeds the threshold value Th1. To do. When it is determined that the difference between the reference inclination α and the inclination β exceeds the threshold Th1 (step S6: YES), the CPU 1011 shifts the process to step S7. When it is determined that the difference between the reference inclination α and the inclination β does not exceed the threshold Th1 (step S6: NO), the CPU 1011 proceeds to step S15. If “YES” is determined in the step S6, the CPU 1011 stores the following information in the RAM 1013 as an element for determining whether or not the condition determined in the step S2 is satisfied. If it is determined in step S2 whether the difference between the reference inclination and the inclination of the image of the preceding document exceeds the threshold Th2, the CPU 1011 stores the difference between the reference inclination α and the inclination β in the RAM 1013. If it is determined in step S2 whether or not the frequency at which the difference between the reference inclination and the inclination of the image of the preceding document exceeds the threshold Th1 exceeds the determined frequency, the CPU 1011 determines that the reference inclination α is The number of times that the difference from the slope β exceeds the threshold Th1 is stored in the RAM 1013.

  In step S <b> 7, the CPU 1011 interrupts the currently executed tilt correction started in step S <b> 3 and the output of the image data being corrected started in step S <b> 4. The CPU 1011 displays information indicating a boundary between data that has been subjected to inclination correction until the inclination correction is interrupted and data that has not been subjected to inclination correction (hereinafter referred to as “boundary”). Information ”) is stored in the RAM 1013. In step S8, the CPU 1011 updates the reference inclination α. Specifically, the CPU 1011 updates the value of the reference inclination α stored in the RAM 1013 to the inclination β detected in step S5.

  In step S9, the CPU 1011 starts tilt correction again. Specifically, the CPU 1011 reads the boundary information from the RAM 1013, and thereby, among the image data being corrected stored in the frame memory, the data that has been subjected to the inclination correction until the inclination correction is interrupted, and the inclination correction. Identify data that has not been performed. The CPU 1011 performs the inclination correction using the inclination γ for the data that has been subjected to the inclination correction before the inclination correction is interrupted. The CPU 1011 also performs inclination correction using the updated reference inclination α for data that has not been subjected to inclination correction until the inclination correction is interrupted. In this way, the image data being corrected stored in the frame memory is corrected based on the inclination β as a whole. The CPU 1011 again stores the image data of the target document that has been tilt-corrected based on the tilt β in the frame memory. Note that the CPU 1011 performs correction for returning the data that has been subjected to the tilt correction until the tilt correction is interrupted to the data before the correction, and then the updated reference tilt α for the entire image data being corrected. The tilt correction may be performed using. In this case, the correction for returning the data whose inclination correction has been performed until the inclination correction is interrupted to the data before the correction is performed before the reference inclination α is updated in step S8. In step S10, the CPU 1011 starts outputting the image data being corrected again. The CPU 1011 starts outputting the image data being corrected by the same process as in step S4.

  In step S11, the CPU 1011 detects the inclination β. Specifically, the CPU 1011 detects the inclination β based on the pre-correction image data read from the frame memory. The CPU 1011 stores the detected inclination β in the RAM 1013. In step S12, the CPU 1011 updates the reference inclination α. Specifically, the CPU 1011 updates the value of the reference inclination α stored in the RAM 1013 to the inclination β detected in step S11. In step S13, the CPU 1011 starts inclination correction using the reference inclination α. The CPU 1011 performs tilt correction by the same process as in step S3. In step S14, the CPU 1011 starts outputting the image data being corrected. The CPU 1011 outputs the image data being corrected to the image forming unit 107 by the same processing as step S4.

  In step S15, the CPU 1011 ends the tilt correction and the output of the image data being corrected. In step S <b> 16, the CPU 1011 determines whether image data has been read from all the originals stacked on the container 1061. When it is determined that the image data has been read from all the documents loaded on the container 1061 (step S16: YES), the CPU 1011 ends the process. If it is determined that there is a document whose image data has not yet been read (step S16: NO), the CPU 1011 shifts the processing to step S1.

  FIG. 5 is a diagram illustrating the update of the reference inclination α. FIG. 5A shows the update of the reference gradient α in the parallel processing mode. FIG. 5B shows the update of the reference gradient α in the individual processing mode. FIG. 5 shows the update of the reference inclination α when reading is performed on five originals. In FIG. 5, “page number” is a number for identifying a document from which an image has been read. The “reference inclination α” indicates the reference inclination α when image reading is started for the document identified by the page number. In this example, the initial value of the reference inclination α is set to 1 °. “Inclination β” indicates the inclination β detected for the document identified by the page number. In FIG. 5A, “| α−β |” indicates the absolute value of the difference between the reference inclination α and the inclination β. In FIG. 5A, the threshold value Th1 is 3 °.

  In the example shown in FIG. 5A, for the first original image, inclination correction is started with the reference inclination α being 1 ° (step S3). The inclination β of the image of the first document is 3 °, and the difference between the reference inclination α and the inclination β is 2 ° (≦ threshold Th1) (step S6: NO). Therefore, for the first original, the inclination correction started in step S3 is not interrupted, and the reference inclination α is not updated. For the second document, the same processing as that for the first document is performed. For the image of the third original, tilt correction is started with the reference tilt α being 1 ° (step S3). The inclination β of the image of the third original is 5 °, and the difference between the reference inclination α and the inclination β is 4 ° (> threshold Th1) (step S6: YES). Therefore, for the third original, the inclination correction started in step S3 is interrupted (step S7), and the reference inclination α is updated to 5 ° (step S8). For the image of the third original, inclination correction is started again with the reference inclination α being 5 ° (step S9). For the fourth and fifth originals, the same processing as that for the first document is performed.

  In the example shown in FIG. 5B, the inclination β of the image of the first document is 2 °, and the reference inclination α is updated to 2 ° (step S12). For the first original image, tilt correction is started with a reference tilt α of 2 ° (step S13). For the second and subsequent documents, the same processing as that for the first document is performed.

  FIG. 6 is a timing chart showing an example of the relationship between image reading by the image reading unit 106 and image data output. FIG. 6 shows how image reading and image data output are performed for four documents in each of the parallel mode and the individual processing mode. The parallel mode shows a state in which the inclination correction is not interrupted and the reference inclination α is not updated (when the determination in step S6 is “NO”). In FIG. 6, “IN” indicates the timing at which an image is read in each mode. “OUT” indicates the timing at which image data is output in each mode. A region indicated by diagonal lines indicates a timing at which the inclination β is detected. An arrow As indicates the timing at which the inclination correction is started. In FIG. 6, the reading of the image of the target document is started after time Td from the time when the output of the image data of the preceding document is completed. As shown in FIG. 6, in the parallel processing mode, the inclination correction and the output of the image data are started before the inclination β is detected. Therefore, in the parallel processing mode, the time difference between the time when the image is read and the time when the image data is output is shortened compared to the individual processing mode. On the other hand, in the individual processing mode, inclination correction and image data output are started after the inclination β is detected. Therefore, in the individual processing mode, the time difference between the time when the image is read and the time when the image data is output is larger than that in the parallel processing mode. In FIG. 6, time Ts indicates a difference in time when the output of the image data of the last document is completed between the parallel processing mode and the individual processing mode (that is, time shortened by the parallel processing mode). In the parallel processing mode, more time is shortened as the number of documents read continuously increases.

  FIG. 7 is a timing chart showing another example of the relationship between image reading and image data output in the parallel processing mode. FIG. 7 shows a state where the inclination correction is interrupted and the reference inclination α is updated for the second original (when the determination in step S6 is “YES”). In this case, for the second original, when the inclination β is detected, the inclination correction and the output of the image data are interrupted (step S7), and the reference inclination α is updated (step S8). In addition, at the timing indicated by the arrow Ar, inclination correction using the updated reference inclination α and output of image data are started. As described above, when the difference between the reference inclination α and the inclination β exceeds the threshold value Th1, the reference inclination α is updated to the inclination β, and image data that has been corrected for inclination using the updated reference inclination α is output. Is done. Therefore, when the difference between the reference inclination α and the inclination β exceeds the threshold Th1, an error in inclination correction is reduced.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. Hereinafter, some modifications will be described. Two or more of the modifications described below may be used in combination.

  The parallel processing mode described in the embodiment is not necessarily used together with the individual processing mode. In this case, the process of step S2 shown in FIG. 4 and the processes of step S11 to step S14 are omitted.

  The threshold Th1 and the threshold Th2 may be determined separately for the case where the slope β is equal to or greater than the reference slope α and the case where the slope β is smaller than the reference slope α.

  The condition of step S2 is not limited to the condition described in the embodiment. For example, for a plurality of preceding documents, it may be determined whether or not the difference between the reference inclination and the inclination of the image of the preceding document has exceeded a threshold value Th1 for a predetermined number of times.

  The hardware configuration of the image forming apparatus 1000 is not limited to the configuration shown in FIGS. The image forming apparatus 1000 may have any hardware configuration as long as the processing of each step shown in FIG. 4 can be executed. For example, the RAM 1013 may have two or more frame memories. In this case, one frame memory may be used for correcting the inclination of the image data of the target document, and the other frame memory may be used for detecting the inclination β.

  In the embodiment, a program executed by the image forming apparatus 1000 includes a magnetic recording medium (magnetic tape, magnetic disk (HDD, FD (Flexible Disk)), etc.), an optical recording medium (optical disk (CD (Compact Disk), DVD ( Digital Versatile Disk))), magneto-optical recording medium, semiconductor memory (flash ROM, etc.) and the like may be provided in a state stored in a computer-readable recording medium. The program may be downloaded via a network such as the Internet.

  DESCRIPTION OF SYMBOLS 1000 ... Image forming apparatus, 11 ... Document conveying means, 12 ... Image reading means, 13 ... Storage means, 14 ... Correction means, 15 ... Detection means, 16 ... Update means, 17 ... Image forming means, 101 ... Control part, 1011 ... CPU, 1012 ... ROM, 1013 ... RAM, 102 ... communication unit, 103 ... storage unit, 104 ... display unit, 105 ... input unit, 106 ... image reading unit, 107 ... image forming unit, 1061 ... container, 111 ... sending Roll, 112 ... first feed roll, 113 ... pre-registration roll, 114 ... registration roll, 1062 ... platen glass, 121 ... full rate carriage, 122 ... half rate carriage, 115 ... second feed roll, 116 ... out roll, 123 ... imaging Lens 124: CCD image sensor 1063 Storage unit

Claims (6)

Reading means for reading an image from a document;
Conveying means for sequentially conveying a plurality of documents to the reading means;
Storage means for storing the inclination of the image;
Correction means for correcting the inclination of the image of the document read by the reading means based on the inclination stored in the storage means;
In parallel with the correction by the correction means, detection means for detecting the inclination of the image of the document,
When the difference between the inclination stored in the storage means and the inclination detected by the detection means exceeds a first threshold, the inclination stored in the storage means is changed to the inclination detected by the detection means. Updating means for updating,
The correction means includes
When the inclination stored in the storage means is updated by the updating means, the correction being executed is interrupted, and the inclination of the image of the document is corrected based on the updated inclination,
An image reading apparatus that corrects an inclination of an image of the next original read by the reading unit based on an inclination stored in the storage unit when reading the next original of the original. When the inclination detected by the detection means satisfies a predetermined condition,
The update means updates the inclination stored in the storage means to the inclination detected by the detection means, regardless of whether the difference exceeds the first threshold value,
The image reading apparatus according to claim 1, wherein the correction unit starts the correction after the inclination stored in the storage unit is updated by the update unit. The image reading apparatus according to claim 2, wherein the determined condition is that a frequency at which the difference exceeds the first threshold exceeds a determined frequency. The image reading apparatus according to claim 2, wherein the determined condition is that the difference exceeds a second threshold value that is larger than the first threshold value. Reading means for reading an image from a document;
Conveying means for sequentially conveying a plurality of documents to the reading means;
Storage means for storing the inclination of the image;
Correction means for correcting the inclination of the image of the document read by the reading means based on the inclination stored in the storage means;
In parallel with the correction by the correction means, detection means for detecting the inclination of the image of the document,
When the difference between the inclination stored in the storage means and the inclination detected by the detection means exceeds a first threshold, the inclination stored in the storage means is changed to the inclination detected by the detection means. Updating means for updating, and image forming means for forming an image whose inclination is corrected by the correcting means on a recording medium,
The correction means includes
When the inclination stored in the storage means is updated by the updating means, the correction being executed is interrupted, and the inclination of the image of the document is corrected based on the updated inclination,
An image forming apparatus for correcting an inclination of an image of the next original read by the reading unit based on an inclination stored in the storage unit when reading the next original of the original. In a computer having reading means, conveying means, storage means, and control means,
The reading means reading an image from a document;
The conveying means sequentially conveys a plurality of documents to the reading means;
Storing the inclination of the image read from the document;
The control means correcting the inclination of the image of the document read by the reading means based on the inclination stored in the storage means;
In parallel with the correcting step, the control means detects the inclination of the image of the document;
When the difference between the inclination stored in the storage means and the detected inclination exceeds a first threshold, the control means interrupts the correction that is being executed and is stored in the storage means correcting the tilt of the image of the document on the basis of the slope after the slope has been updated to the slope which is the detection, the tilt of the next document image of the document read by the reading means, the inclination of the updated And a program for executing the step of correcting based on.