JP2006067329A - Document reading apparatus and document reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document reading apparatus capable of correctly detecting a document size in a short time and scanning only an accurate document reading region even if a set document is slightly deviated.
When scanning a document by a CCD sensor and reading a document image without performing pre-scanning, the area sensor 300 captures an image of the entire platen glass surface. Based on the photographed image, the amount of deviation in the main scanning direction and the sub-scanning direction is detected from the reference position of the document placed on the platen glass surface 102, and the size of the document is detected. Then, an image reading operation of the document by the CCD sensor 109 is performed so as to shift the detected deviation amount according to the size of the document.
[Selection] FIG.

Description

  The present invention relates to an original reading apparatus and an original reading method for reading an image while scanning an original.

  Conventionally, products that place importance on first copy output time (FCOT) have been developed as image forming apparatuses equipped with this type of document reading apparatus. The first copy time is the time from when the original is set and the copy button (start button) is pressed to when the first copy sheet comes out. As a result, even in the document reading apparatus, a document size detection function for performing size detection when the pressure plate is opened and closed without a pre-scan operation is mounted as a standard function on a product. With this document size detection function, when a standard size document is detected, the document size can be specified before executing the document reading operation with the start key. By executing it, the FCOT can be shortened.

  Further, there is known an original reading apparatus that performs size detection in the main scanning direction by a CCD (see Patent Document 1). In this document reading apparatus, the reflection type photosensor in the main scanning direction can be omitted as compared with the size detection of the standard document using only the reflection type photosensor so far. In addition, the number of parts and the cost can be reduced, and the detectable standard document size can be expanded.

  In the copying machine, when the image information is read by the image sensor and stored in the memory, the size of the document placed on the document table is detected by a reflective photo sensor or the like, and based on the detected size information of the document, A method (fixed reading method) in which an area where a document exists is scanned by a line sensor and read is generally performed. When an automatic document feeder (ADF) is used, the document size is detected by the width of the document and the time when the trailing edge passes the sensor during document conveyance, and the document conveyed by a fixed line sensor is read. (Skip reading method) is also generally performed. In either reading method, the read line data is temporarily stored in the image memory and then output to the output device as image data.

At this time, if the document is set obliquely at a position deviated from the reference position, the document deviation and inclination are reflected as they are in the image stored in the image memory, and image data having the position deviation and inclination is output. Will be. On the other hand, when reading out the image data stored in the image memory, a measure for performing an inclination correction process is taken. However, this tilt correction processing requires a large amount of memory and also affects the first copy time and the like. On the other hand, a document reading apparatus that performs an inclination correction process in real time has been studied (see Patent Document 2).
JP-A-8-79463 JP 2001-103273 A

  However, in the conventional document reading apparatus that detects the standard document size, if the document set with respect to the document setting position (reference position) is displaced, the document size is erroneously detected or the document reading area is scanned correctly. could not. In addition, the document reading apparatus that performs the above-described conventional tilt correction process requires a correction memory and cannot correct the tilt when the tilt exceeds the maximum correction amount.

  Therefore, the present invention provides a document reading apparatus and a document reading method capable of correctly detecting a document size in a short time and scanning only an accurate document reading area even if a set document is slightly deviated. Objective. Another object of the present invention is to provide a document reading apparatus and a document reading method capable of correcting in real time regardless of the inclination of the document.

  In order to achieve the above object, an original reading apparatus of the present invention is an original reading apparatus that reads an image of an original while scanning the original with a reading means, and the original is set before the scanning of the reading means is started. An imaging unit having a two-dimensional imaging device for imaging a document table, a document setting state detection unit for detecting the document setting state based on the captured image of the document table, and an image of the imaged document table A document size detecting unit for detecting the size of the document based on an image; and a reading control unit for controlling an image reading operation of the document by the reading unit based on the detected setting state of the document and the size of the document. It is provided with.

  The document reading method of the present invention is a document reading method for reading an image of a document while scanning the document by the reading unit, and the document table on which the document is set by the imaging unit before the scanning of the reading unit is performed. An imaging step of imaging using a two-dimensional imaging device, a document setting state detecting step of detecting the setting state of the document based on the captured image of the document table, and a basis of the captured image of the document table A document size detecting step for detecting the size of the document, and a reading control step for controlling an image reading operation of the document by the reading unit based on the detected document setting state and the document size. Features.

  The document reading device of the present invention is a document reading device that reads an image of a document while scanning the document set on the document table by the reading unit, and the document table is scanned before the scanning of the document by the reading unit is started. Imaging means having a two-dimensional imaging device for imaging, original table image storage means for storing the imaged image of the original table, acquisition means for acquiring information about the original from the stored original image, A scanning range determining unit that determines a scanning range based on information about the acquired document, and a selection that selects image data in a predetermined range from images read by the reading unit while scanning the determined scanning range And image storage means for storing the selected image data in an image memory.

  The document reading method of the present invention is a document reading method for reading an image of a document while scanning a document set on a document table by a reading unit, wherein the document table is scanned before the scanning of the document by the reading unit is started. An imaging step of capturing an image using a two-dimensional image sensor, a document table image storing step for storing the captured image of the document table, and an acquisition step of acquiring information about the document from the stored document table image; A scanning range determination step for determining a scanning range based on the acquired information on the original, and image data in a predetermined range are selected from images read by the reading unit while scanning the determined scanning range. A selection step; and an image storage step of storing the selected image data in an image memory.

  According to the document reading apparatus of the first aspect of the present invention, before the scanning of the reading unit is started, the document table on which the document is set is imaged by the two-dimensional image sensor of the imaging unit, and the captured image of the document table is used as a basis. In addition, the original setting state is detected, the original size is detected based on the captured image on the original table, and the original image is read by the reading unit based on the detected original setting state and original size. Since the operation is controlled, the original size can be detected correctly and only the accurate original reading area can be scanned in a short time even if the set original is slightly shifted. Therefore, even if the original is not set correctly, only the original can be scanned, and the first copy time can be shortened.

  According to the document reading apparatus of the third aspect, the document size can be accurately detected. According to the document reading apparatus of the fourth aspect, it is possible to eliminate erroneous determination of the presence or absence of a document. According to the document reading apparatus of the fifth aspect, the presence or absence of the document can be reliably detected. According to the document reading apparatus of the sixth aspect, the image reading range can be reduced.

  According to the document reading apparatus of the present invention, the document table is imaged before the scanning of the document by the reading unit is started, the captured image of the document table is stored, and the stored image of the document table is stored. Information on the original is acquired from the image, a scanning range is determined based on the acquired information on the original, and image data in a predetermined range is selected from images read by the reading unit while scanning the determined scanning range. Since the selected image data is stored in the image memory, it can be corrected in real time regardless of the size of the original. In other words, when stored in the image memory, it is possible to correct in real time any document set at any position on the document table and with any inclination. Appropriate image data can be obtained using only the document size image memory. Can be obtained. Also, the first copy time can be shortened.

  According to the document reading apparatus of the ninth aspect, since the image data can be output while being read, the first copy time can be shortened. According to the document reading apparatus of the tenth aspect, the image data can be stored in the image memory regardless of the deviation or inclination of the document. According to the document reading apparatus of the thirteenth aspect, the number of parts can be reduced.

  Embodiments of a document reading apparatus and a document reading method of the present invention will be described with reference to the drawings. The document reading apparatus according to this embodiment is mounted on an image forming apparatus.

[First Embodiment]
FIG. 1 is a diagram illustrating an internal configuration of the image forming apparatus according to the first embodiment. The image forming apparatus mainly includes a reader unit 1 and a printer unit 2. The reader unit 1 is equipped with an automatic document feeder (DF) 101, and the documents stacked on the automatic document feeder 101 are sequentially conveyed onto the platen glass surface 102 one by one. When the original is conveyed to a predetermined position on the original platen glass surface 102, the scanner unit 104 provided in the reader unit 1 starts to move, and the lamp 103 inside thereof is turned on to irradiate the original. When the DF is not used, the user sets the document directly on the platen glass surface 102. Reflected light from the document is input to a CCD image sensor unit (hereinafter simply referred to as a CCD or a CCD sensor) 109 via mirrors 105, 106, 107 and a lens 108. Reflected light from the original input to the CCD 109 is photoelectrically converted by the CCD 109, and the electric signal is sent to the image processing unit 110. The image processing unit 110 performs image processing on the image signal in accordance with various setting values set on an operation panel described later. Further, a document detection sensor 401 having a built-in area sensor 300 (see FIG. 3) capable of photographing the entire document table glass surface 102 is attached to the bottom surface of the frame of the reader unit 1.

  The image signal that has been subjected to image processing by the image processing unit 110 is input to the exposure control unit 201 in the printer unit 2. The exposure control unit 201 modulates an optical signal according to the input image signal and irradiates the photoconductor 202. The latent image formed on the photoconductor 202 by this irradiation light is developed by the developing unit 203.

  The transfer paper is transported from the transfer paper stacking unit 204 or the transfer paper stacking unit 205 so as to match the timing of the development front, and the developed image is transferred to the transfer paper in the transfer unit 206. When the transferred image is fixed on the transfer paper by the fixing unit 207, the transfer paper is discharged from the paper discharge unit 208 to the outside of the apparatus. The printer unit 2 is equipped with a sorter 220, and the transfer paper output from the paper discharge unit 208 is discharged to the sorter 220.

  In addition, when outputting sequentially read images on both sides of a single transfer sheet, the transfer sheet (output sheet) fixed by the fixing unit 207 is once transported to the sheet discharge unit 208 and then the transport direction of the sheet is reversed. Then, the paper is transported to the re-feeding transfer paper stacking section 210 by the transport direction switching member 209. Then, when the next document is prepared, the document image is read and the transfer sheet on which the image is formed on one side is fed from the re-feeding transfer sheet stacking unit 210 as in the above process. An image is formed on one side. As a result, two document images are output on the front and back surfaces of one transfer sheet.

  FIG. 2 is a view showing an appearance of an operation unit (panel) provided in the reader unit 1. In addition to the display unit 253, the operation panel 4 is provided with various keys such as a function key 251, a numeric key 254, and a start key 256. The display unit 253 displays an operation status, various operation keys, a message, and the like. A touch panel is affixed to the surface of the display unit 253, and each display location functions as a selection key by touching (pressing) each display location displayed on the display unit 253. For example, the display part of “magnification” functions as a selection key for setting the magnification. The magnification key 263 is pressed when setting the copy magnification (%).

  The message display field 261 displays an operation status, a message, and the like. The same size key 262 is pressed when setting an equal size (100%) copy. The paper selection key 264 is pressed when selecting a paper. The sorter key 265 is pressed when setting the sort mode. The double-sided key 266 is pressed when switching to the double-sided type setting screen and setting the double-sided type. The density key 267 is pressed when adjusting the copy density. The character key 268 is pressed when selecting the character mode or the photo mode. The application mode key 269 is pressed when switching to the application mode setting screen and setting various application modes. The system status key 270 is pressed when displaying the system status.

  The numeric keypad 254 is a key for inputting numbers, and is used for setting the number of copies for one original, for example. The start key 256 is pressed when starting a document reading operation. The stop key 271 is pressed when the copy operation is finished. The reset key 272 is pressed when returning the copy mode to the standard mode. The guide key 273 is pressed when setting the guide mode. The user key 274 is pressed when setting the user mode. The interrupt key 275 is pressed when performing an interrupt copy. The function key 251 is a key for performing one-touch switching between a copy operation, a BOX operation, and an extended function. Specifically, the copy key 281 is pressed when using the copy function. The box key 282 is pressed when using the box function. The extension key 283 is pressed when using the extension function. Here, the BOX function is a function for accumulating scanned images in a hard disk (not shown) prepared in the image forming apparatus main body. The power saving key 284 is pressed when setting the power saving mode. The power key 285 is pressed when turning on / off the power.

  The display unit 253 of the operation panel 4 displays a document size detection result determined without erroneous detection even when there is a document misalignment, as will be described later. On the copy operation screen, when the paper accommodated in the printer unit 2 conforms to the detection result of the document size, the document of that size is automatically selected.

  FIG. 3 is a block diagram showing an electrical configuration of the controller unit 250 in the reader unit 1. The controller unit 250 has a configuration in which a CPU 308, a ROM 307, a RAM 306, drivers 305 and 309, an I / O interface 351, a reader memory 301, a density determination unit 302, a buffer memory 303, and a CCD control unit 313 are connected via a bus 315. Have. The reader memory 301 receives and stores output data from the area sensor 300. The density determination unit 302 determines the density of data in the reader memory 301 in units of pixels and determines one of three levels of white density, gray density, and black density. This determination result is stored in the buffer memory 303 by the CPU 308. The ROM 307 stores a control program shown in a flowchart described later. The CPU 308 controls each unit of the reader unit 1 according to a control program stored in the ROM 307. The RAM 306 is used as a work area for the CPU 308. A pressure plate opening / closing sensor 405 described later is connected to the I / O interface 351.

  As will be described later, the controller unit 250 drives the area sensor 300 and the LED 304 in the document detection sensor 401 using a driver 305 to perform document size detection and the like. The LED 304 illuminates the entire document table. Further, when reading a document, the optical motor 311 and the lamp 103 are driven using the driver 309 and the CCD sensor 109 is driven using the CCD control unit 313, and the image data read by the CCD sensor 109 is converted into the image processing unit 110. Send to.

  When there is a document deviation, the document reading operation is set by the CCD control unit 313, and the image read by the CCD sensor 109 is transmitted to the image processing unit 110 while being shifted by the measured document deviation amount. The FIG. 4 is a diagram showing image capture control when document misalignment occurs. Here, the A5 size document is placed from the document abutting section 380 by a document displacement amount Y in the main scanning direction and by a document displacement amount X in the sub-scanning direction.

  In the image capture control in the image processing unit 110, an image capture permission signal H-ENABLE in the main scanning direction, which is an effective signal when capturing an image output from the CCD control unit 313 to the CCD sensor 109, and sub-scanning. The A5 size original reading operation is performed without recognizing the original deviation by shifting the direction image take-in permission signal V-ENABLE by the original deviation amounts Y and X, respectively. That is, in the image processing unit 110, the document image in the document reading area in which the image capturing permission signal H-ENABLE in the main scanning direction and the image capturing permission signal V-ENABLE in the sub scanning direction are each at the H level is captured. .

  FIG. 5 is a perspective view showing the appearance of the reader unit 1. In FIG. 5, a pressure plate 403 capable of opening and closing the original table glass surface 102 is attached to the reader unit 1 in place of the original conveying device 101. FIG. 6 is a diagram schematically showing a mechanism for detecting opening and closing of the pressure plate. The pressure plate 403 can be opened and closed with respect to the platen glass surface 102 by a hinge mechanism (not shown). In the vicinity of the hinge mechanism that opens and closes the pressure plate 403, a pressure plate open / close detection unit including a pressure plate open / close sensor 405 and a pressure plate open / close flag 404 is provided. The pressure plate open / close sensor 405 is a photo interrupter, and when the pressure plate 403 is closed, the pressure plate open / close flag 404 formed integrally with the pressure plate 403 blocks the light of the photo interrupter or when the pressure plate 403 is opened, it is integrated with the pressure plate 403. The pressure plate open / close flag 404 formed in (1) detects the open / close state of the pressure plate 403 by releasing the light shielding of the photo interrupter. The pressure plate opening / closing sensor may simply detect the open / closed state depending on whether the opening / closing angle is equal to or less than a predetermined angle, or may detect the opening / closing angle, and the result is The determination as to whether it is in the open state or the closed state may be left to the control unit.

  Further, the document detection sensor 401 including the area sensor 300 and the LED 304 described above is installed inside the reader unit 1, and the LED 304 is turned on to capture an image with the entire surface of the platen glass 102 illuminated. . As a result of this imaging, the presence or absence of a document on the platen glass surface 102 is detected. Further, when the pressure plate 403 is opened and closed while the document 402 is placed, document displacement detection and document size detection described later are started. In the document misalignment detection, the LED 304 in the document detection sensor 401 is turned on, and the area sensor 300 detects reflected light from the document. That is, in a state where the pressure plate 403 is not closed, light from the LED 304 is reflected when a document is present, and light from the LED 304 is not reflected when a document is not present.

  Further, the original plate surface of the pressure plate 403 is a white plate. In this embodiment, the reading value by the original detection sensor 401 in the open state of the pressure plate 403 (black determination at the position of no original) and the closed state of the pressure plate 403 are displayed. An algorithm is used that compares the read value (white determination at the position where there is no document) and determines that there is no document if the determination result varies. This detection method is called “twice reading detection”. This “double reading detection” will be described later.

  An original misalignment detection and original size detection method will be described. FIG. 7 is a diagram showing the sub-scanning document misalignment detection line p, the main-scanning document misalignment detection line q, and the detection position set on the platen glass surface. Eight detection positions are set on the sub-scanning document deviation detection line p, and six detection positions are set on the main-scanning document deviation detection line q. No. No. 1 detection position (detection position 1), No. 1 No. 11 detection position (detection position 11) is a position for measuring document misalignment. 2-No. 8, no. 12-No. Sixteen detection positions (detection positions 2 to 8 and 12 to 16) are positions for document size detection.

  FIG. 8 is a graph showing the reading luminance with respect to the main scanning position for each opening / closing angle of the pressure plate 403. The measurement of this graph is performed in a “no original” state. When a document is placed, the reading luminance is at a constant level regardless of the opening / closing angle of the pressure plate. In the figure, reference numerals k, l, c, d, e, f, g, h, i, and j denote the pressure plate opening / closing angles (pressure plate angles) of 0 °, 1 °, 2 °, 3 °, 4 °, respectively. Corresponding to 5 °, 7 °, 10 °, 12 ° and 15 °. These graphs are substantially represented by a linear curve, and the reading luminance in pixel units decreases toward the main scanning direction (on the side opposite to the opening / closing fulcrum of the pressure plate). Further, the threshold level Y for determining the white threshold level and the black threshold level used in the density determination process is calculated according to Equation (1), where X is the angle ratio. Here, a is the main scanning position. b is the reading luminance in the vicinity of the main scanning position 0.

Y = aX + b (1)
Then, when determining the black threshold level, the value of b is set to “100” from the reading luminance at the detection platen angle 5 ° at the detection position 12 (main scanning position 3300). Further, the angle ratio X is calculated from a linear curve of a platen angle of 5 °. The pressure plate angle 5 ° is an angle when a sudden pressure plate closing is assumed. On the other hand, when determining the white threshold level, the value of b is set to “200” based on the reading luminance at the detection position 16 (main scanning position 7000) at a pressure plate angle of 1 °. The angle ratio X is calculated from a linear curve of a platen angle of 1 °. The platen angle 1 ° is an angle when a thick original is assumed. Each of the white and black threshold levels calculated using Equation (1) obtained in this way increases or decreases according to the pixel position in the main scanning direction. That is, each threshold level is lower when the pixel position is larger, and each threshold level is higher when the pixel position is smaller.

  FIG. 9 is a table showing the contents of processing performed for each detection position. The detection position 11 in the main scanning direction and the detection position 1 in the sub-scanning direction are reference positions for measuring document misalignment as described above, and are not determined in combination with other detection positions. In the figure, cells marked with “-” are cells that do not correspond to such a combination. The detection positions 2 to 8 in the sub-scanning direction and the detection positions 12 to 16 in the main scanning direction are positions for detecting the document size. These detection positions for detecting the document size are breaks of various document sizes. (Refer to FIG. 7).

  In this document size detection process, the document size is determined based on the position determined as “document exists” as a result of performing “twice reading detection” in the range of several pixels in the reverse scanning direction from each detection position. . For example, when an A5R original is set, it is determined that “original is present” up to the detection position 4 in the sub-scanning direction, and “original is present” up to the detection position 12 in the main scanning direction. When this document size detection process is performed, the detection positions 2 to 8 and the detection positions 12 to 16 can be moved in the respective directions by the document shift amount measured by the document shift measurement process described later. Each detection position is set in a two-dimensional area composed of n pixels in the main scanning direction and m pixels in the sub-scanning direction, and the average value of the reading values of all the pixels constituting this detection position is calculated. The presence / absence of a document at each detection position may be determined based on the average value.

  An original reading operation of the image forming apparatus having the above configuration will be described. FIG. 10 is a flowchart showing the document size detection processing procedure. This processing program is stored in the ROM 307 and executed by the CPU 308. First, it is determined whether or not the pressure plate 403 has shifted from the open state to the closed state based on the output of the pressure plate opening / closing sensor 405 (step S1). If it has not shifted from the open state to the closed state, the process of step S1 is repeated. On the other hand, when it is determined that the pressure plate 403 has shifted from the open state to the closed state, the LED 304 in the document detection sensor 401 is turned on (step S2).

  After the LED 304 is turned on, a first size detection process is performed (step S3). Details of the size detection process will be described later. After the first size detection process, 100 ms is waited (step S4), and it is determined whether or not the pressure plate 403 is completely closed (step S5). The determination as to whether or not the pressure plate 403 has been completely closed is made based on whether or not the detection result of the closed state of the pressure plate 403 has continued for a predetermined time. Be recognized. On the other hand, when the pressure plate 403 is not completely closed, the second and subsequent size detection processing is performed (step S6). Details of the second and subsequent size detection processes will also be described later. When the second and subsequent size detection processes are completed, the process returns to step S4. That is, the same processing is repeated until it is determined that the pressure plate 403 is in a completely closed state.

  On the other hand, if it is determined in step S5 that the pressure plate 403 is completely closed, the final size detection process is performed (step S7). Details of the final size detection process will be described later, as in the processes of steps S3 and S6. Thereafter, the LED 304 in the document detection sensor 401 is turned off (step S8), and this process is terminated.

  FIG. 11 is a flowchart showing the size detection processing procedure in steps S3, S6 and S7. First, the image sensor 102 is imaged by the area sensor 300, and it is determined whether or not it is the first size detection process (step S11). If it is determined that it is the first size detection process, the density determination of the shift detection line pixels in the main scanning document shift detection line q and the sub-scan document shift detection line p is performed (step S18). In this shift detection line pixel density determination, the density determination unit 302 performs data density determination on the data output from the area sensor 300 and stored in the reader memory 301. Details of the density determination processing of the shift detection line pixel will be described later.

  After the density detection process of the shift detection line pixel, the density determination information as a result is stored in the buffer memory 303 (step S19). Thereafter, the document size detection position in the main / sub-scanning direction is set to the default position (document break position in FIG. 7) (step S20), and the process returns to the main process.

  On the other hand, if it is determined in step S11 that it is not the first size detection process, that is, if it is the second or subsequent size detection process, a data change detection process for the shift detection line pixel is performed (step S12). The data change detection process of the shift detection line pixel will be described later. In the vicinity of the document abutting portion, it is determined whether or not “data change” is recognized with respect to the previous density determination result, that is, “no document” (step S13). Here, the vicinity of the document abutting portion is a range of several pixels in the main scanning direction and the sub scanning direction from the detection position 11 in the main scanning direction and the detection position 1 in the sub scanning direction shown in FIG. When it is recognized that “data has changed”, document deviation measurement is performed (step S14). This document deviation measurement process will be described later.

  After the document deviation measurement, the document size detection position in the main scanning direction and the sub-scanning direction is moved and set by the measured document deviation amount (step S15). Then, it is determined whether or not “data change” is recognized within a range of several pixels in the reverse scanning direction from each document size detection position, that is, “no document” (step S16). If it is recognized that “there is data change”, the document size is determined according to the table of FIG. 9 (step S17), and the process returns to the main process. On the other hand, if “no data change” is recognized in step S16, the process returns to the main process.

  FIG. 12 is a flowchart showing the procedure for determining the density of the shift detection line pixel in step S18. This processing is executed by the density determination unit 302, and density determination is performed for all pixels in the shift detection line in the main scanning direction and the shift detection line in the sub-scanning direction. First, it is determined whether the luminance value of the target pixel in the reader memory 301 is equal to or higher than the white threshold level (step S31). If it is determined that the white threshold level is exceeded, the target pixel is determined to have a white density (step S35), and the process returns to the original process.

  On the other hand, when it is determined in step S31 that it is not equal to or higher than the white threshold level, it is determined whether or not the luminance value of the target pixel in the reader memory 301 is less than the black threshold level (step S32). If it is determined that the level is less than the black threshold level, the target pixel is determined to have a black density (step S34), and the process returns to the original process. On the other hand, if it is determined that the level is not less than the black threshold level, the target pixel is determined to have a gray density (step S33), and the process returns to the original process.

  FIG. 13 is a flowchart showing the data change detection processing procedure of the shift detection line pixel. This process is executed by the density determination unit 302, and is performed for all pixels in the deviation detection line in the main scanning direction and the deviation detection line in the sub-scanning direction. First, the density determination process of the shift detection line pixel is performed (step S41). From the processing result in step S41 and the density determination result stored in the buffer memory 303 in step S19, the presence / absence of a document is determined as described below.

  First, it is determined whether or not the first determination is black density (step S42). Since the first determination result is stored in the buffer memory 303, it is used for the density determination result of each pixel. If it is determined that the first determination is not black density, it is determined whether or not the first determination is white density (step S43). If it is determined that the first determination is not white density, it is determined that there is a gray density for the target pixel, and “original exists” is determined (step S44), and the process returns to the original processing.

  On the other hand, if it is determined in step S43 that the first determination is white density, it is determined whether or not the current density determination result, which is the execution result of step S41, is black density (step S45). If it is determined that there is a density, it is determined that there is no original, assuming that strong external light exists for the target pixel and the first and second times have become white density / black density, respectively (step S46). ) And return to the original process. On the other hand, if it is determined that the density is not black, it is determined in step S44 that there is an original document, assuming that the first and second times are white density / white density, respectively.

  If it is determined in step S42 that the first determination is black density, it is determined whether the current density determination result, which is the execution result of step S41, is white density (step S47). If it is determined that there is a density, “no original” is determined for the target pixel, assuming that the first density / second density is black density / white density (step S48), and the process returns to the original process. On the other hand, if it is determined that the current density determination result is not white density, it is determined that there is a document in step S44, assuming that the first density / second time is black density / black density, respectively.

  FIG. 14 is a flowchart showing the document misalignment measurement processing procedure in step S14. First, a pixel determined to be “no document” (simply referred to as “no document pixel”) is searched for from the detection position 11 in the main scanning direction and the detection position 1 in the sub scanning direction (step S51). This search uses the document presence / absence determination result shown in FIG. From the retrieved no-document pixel, a pixel determined as “original exists” in the main scanning direction and the sub-scanning direction (simply referred to as “original document pixel”) is searched (searched) (step S52). Then, the number of pixels with no document up to the pixels with document is set as the document deviation amount (step S53), and the process returns to the original process.

  FIG. 15 is a flowchart showing a document reading operation processing procedure. This processing program is stored in the ROM 307 and executed by the CPU 308. First, the lamp 103 is turned on (step S61). It is determined whether there is a document misalignment (step S62). If it is determined that there is no document deviation, the document deviation amount is set to 0 for the CCD controller 313 (step S63). On the other hand, if it is determined that there is document deviation, the document deviation amount for the CCD control unit 313 is set to the document deviation amount set in step S53 (step S67).

  After the processes in steps S63 and S67, the optical motor 311 is driven to perform a document scanning operation according to the document size (step S64). Then, it waits until the document scanning operation is completed (step S65). When the document scanning operation is completed, the lamp 103 is turned off (step S66), and this processing is terminated.

  As described above, according to the first embodiment, when the document is scanned by the CCD sensor 109 and the document image is read without performing pre-scanning, the area sensor 300 captures the entire surface of the document table glass surface 102. To do. Based on the photographed image, the amount of deviation in the main scanning direction and the sub-scanning direction is detected from the reference position of the document placed on the platen glass surface 102, and the size of the document is detected. Then, since the image reading operation of the document is performed by the CCD sensor 109 so as to shift the detected deviation amount according to the size of the document, even if the document placed on the document table glass surface 102 is slightly shifted, The document reading area can be scanned correctly without erroneously detecting the document size. Therefore, even if the document is not set correctly, only the portion of the document on the platen glass can be scanned, and the first copy time can be shortened.

  In the above-described embodiment, the document reading operation in the case where the document is placed on the platen glass surface by opening and closing the pressure plate is shown, but the same applies to the case where the document feeding device transports the document to the platen glass surface. Of course, it is applicable to.

[Second Embodiment]
As in the first embodiment, the internal configuration of the image forming apparatus in the second embodiment is mainly composed of the reader unit 1 and the printer unit 2 (see FIG. 1), and therefore the same components are the same. The description is omitted by using the reference numeral. In the second embodiment, a controller unit 3 is provided between the reader unit 1 and the printer unit 2.

  As described above, the document detection sensor 401 is attached to the bottom surface inside the reader unit 1, and the document table glass surface 102 is imaged over the entire surface by the area sensor 300 inside the reader sensor 1. As the area sensor 300, a two-dimensional CCD camera is used. Then, the reader unit 1 calculates a deviation amount (offset) and an inclination of the document from the reference position (abutting portion) based on the image captured by the area sensor 300. The calculation of the deviation amount and inclination of the document will be described later. These information (parameters) calculated by the reader unit 1 are transferred to the reader interface 501 in the controller unit 3 and used for address conversion when image data is stored in the reader memory 502, as will be described later. When the original is conveyed to a predetermined position on the original table glass surface 102, the lamp 103 is turned on, and the scanner unit 104 illuminates the original placed on the original table glass 102 while moving. At this time, the range in which the scanner unit 104 moves is only an area corresponding to the document size.

  A document feeding control unit 11 is connected to the reader unit 1, and the document feeding control unit 11 includes a CPU, a ROM, a RAM, and the like (not shown), and commands from the controller unit 3. Accordingly, the automatic document feeder 101 is controlled by communicating with the reader unit 1. The reader unit 1 is provided with an operation panel 4. Since the display unit and various keys arranged on the operation panel 4 are the same as those in the first embodiment, description thereof is omitted.

  FIG. 16 is a block diagram showing the configuration of the controller unit 3 that controls the reader unit 1 and the printer unit 2. The controller unit 3 includes a reader interface 501 connected to the reader unit 1, a printer interface 510 connected to the printer unit 2, a reader memory 502, an encoder 503, a compressed image memory 504, a decoder 505, a page memory 506, a CPU 507, and a RAM 508. And a ROM 509 connected through a bus 515. The reader memory 502 temporarily stores at least one page of image data before compression of the image read by the reader unit 1. The encoder 503 compresses the image data stored in the reader memory 502. The compressed image memory 504 stores image data for a plurality of pages compressed by the encoder 503. The decoder 505 analyzes (decompresses) the compressed image data stored in the compressed image memory 504 and develops it on the page memory 506. The ROM 509 stores a control program. The CPU 507 controls each unit of the controller unit 3 according to a control program stored in the ROM 509. The RAM 508 is used as a work area for the CPU 507.

  In the controller unit 3, when the area sensor 300 in the reader unit 1 detects a deviation amount and an inclination from the reference position of the document, these pieces of information are transferred to the reader interface 501 and the document read by the reader unit 1 is read. The image data is temporarily stored (buffered) in the reader memory 502 via the reader interface 501. When the image data in the reader memory 502 is compressed by the encoder 503, it is stored in the compressed image memory 504. In a normal copying operation, the image data stored in the compressed image memory 504 is analyzed (expanded) by the decoder 505, and when the image data is expanded on the page memory 506, the image is output to the printer unit 2. When the image is normally output, the image data in the compressed image memory 504 is deleted. Note that the resolution of the document image read by the CCD 109 in the main scanning direction and the sub-scanning direction is higher than the resolution of the image on the platen glass surface 102 read by the area sensor 30.

  An original reading operation of the image forming apparatus having the above configuration will be described. Specifically, an operation of storing image data in the reader memory 502 while correcting the inclination of the document in real time is shown. FIG. 17 shows the inclination angle, size, and deviation amount from the reference position (document abutting portion) 380 calculated from the image (area sensor image) of the document on the platen glass surface imaged by the area sensor 300. It is a figure which shows (offset). By extracting the boundary line of the document from the area sensor image by edge extraction processing and applying it to a straight line, an offset (ofsX, ofsY) from the reference position 380 at the upper left of the image in the figure, the document Is calculated (papW, PapH) and the inclination (angle a) of the document. These calculated parameters are transferred to the reader interface 501 and used for address conversion of the reader memory 502 in which image data read by the CCD sensor 109 is stored, as will be described later.

  FIG. 18 is a diagram showing a scanning range when a document image is captured using a CCD sensor (line sensor). As shown in FIG. 17, since the range where the document exists is fixed, the image reading operation is performed by limiting the range on the platen glass surface. That is, based on the current scanning position (x coordinate) of the CCD sensor and the calculated parameters, it is calculated which range is valid in the line buffer read by the CCD. Then, coordinate conversion of effective pixel information is performed, and coordinate conversion of other pixel information is unnecessary. Thereby, useless reading operation and conversion processing can be omitted. Here, the reader interface 501 is provided with an address converter (not shown) configured by hardware. After the inclination and offset are corrected by the address converter, the read image data is read out. Is stored in the reader memory 502. FIG. 19 is a diagram showing the correspondence between the document table coordinates on the document table glass surface and the image memory address in the reader memory. When the document table coordinates and the image memory address are represented by (x, y) and (x ′, y ′), respectively, the address conversion formula by the address converter is expressed by an inclination angle a and an offset ( ofsX, ofsY), and is represented by a linear transformation and a linear transformation of the rotation matrix.

  Here, the y-coordinates on the sides 601, 602, 603, and 604 of the area sensor image are represented by mathematical formulas (3), (4), (5), and (6), respectively.

ofsY- (x-ofsX) tan (a) (3)
ofsY + (x-ofsX) / tan (a) (4)
ofsY-papWsin (a) + (x-ofsX-papWcos (a)) / tan (a) (5)
ofsY + papHcos (a)-(x-ofsX-papHsin (a)) tan (a) (6)
FIG. 20 is a diagram illustrating a state where writing and outputting of a document image are performed simultaneously. On the upper side of each of the drawings (A), (B), and (C), the position of the original (reference numeral d in the figure) and the CCD sensor (line sensor) on the original table glass surface (reference numeral e in the figure). In the lower part of each of FIGS. 9A, 9B, and 9C, the read / write state in the image memory (reader memory) is shown. In the figure, time passes from the left figure (A) to the right figure (C). In the figure, a hatched area is a written memory area. Reference numeral f denotes a memory line being written. Here, output of image data is started when image data for one vertical line, that is, image data in the main scanning direction is determined, and a symbol g is a memory line being output. In the present embodiment, the image data is output when the image data for one line is determined. However, it is needless to say that the image data may be output when the image data for a plurality of lines is determined.

  FIG. 21 is a flowchart showing a document reading operation processing procedure. This processing program is stored in the ROM 509 and executed by the CPU 507. First, it waits for the start of the reading operation to be instructed by pressing the start key 256 of the operation panel 4 or the output of the opening / closing signal by the pressure plate opening / closing sensor 405 (step S81). The reader unit 1 is turned on via the reader interface 501 to illuminate the LED 304, irradiate the original platen glass surface 102, and the area sensor 300 instructs the entire image of the original platen glass surface 102 to be imaged. The stored image is stored in the reader memory 502 via the reader interface 501 (step S82).

  Based on the photographed image, the outline of the document is extracted by edge extraction processing (step S83). Further, from the extracted document outline, the document deviation amount (ofsX, ofsY) from the reference position (the abutting portion of the document table glass surface 102), the inclination angle a, and the document size (length in the main scanning direction). A parameter composed of papW and length ppH in the sub-scanning direction is detected (step S84). Based on these parameters, the reading scanning range of the document by the scanner unit 104 (regions l, m, and n in FIG. 18) is determined (step S85), and the image of the document by the CCD sensor 109 is determined within the determined scanning range. A reading operation is performed (step S86). That is, as shown in FIG. 18, the image reading operation of the document by the CCD sensor 109 is not performed in the x-coordinate region where the document does not exist. As described above, in the area where the CCD sensor (line sensor) 109 crosses both sides 601 and 602 of the document (area l in FIG. 18), the y coordinate shown in the expression (3) is used as the reading start position, and the expression (4 The image data in the main scanning direction is read with the y coordinate shown in FIG. In an area where the CCD sensor 109 crosses both sides 601 and 604 of the document (area m in FIG. 18), the y coordinate shown in Expression (3) is used as the reading start position, and the y coordinate shown in Expression (6) is read. The image data in the main scanning direction as the end position is read. Similarly, in a region where the CCD sensor 109 crosses both sides 603 and 604 of the document (region n in FIG. 18), the y coordinate shown in Equation (5) is used as the reading start position, and the y coordinate shown in Equation (6) is used. Image data in the main scanning direction as a reading end position is read.

  When the reading operation of the image data in the main scanning direction is performed, the document table coordinates of the pixel in which the image data exists are converted into the memory address of the reader memory 502 according to Equation (2) (step S87), and the converted memory The image data is stored in the reader memory 502 according to the address (step S88). It is determined whether or not image data for one line in the vertical direction of the document has been stored in the reader memory 502 (step S89). If image data for one line is not stored, the process returns to step S86 and the same processing is repeated. On the other hand, when the image data for one line is stored, the determined image data for one line is output from the reader memory 502 (step S90). The output image data is subjected to a compression process or the like by the encoder 503, and then an image forming operation is performed. Thereafter, it is determined whether or not the entire scanning range determined in step S85 has been scanned (step S91). If not all are scanned, the process returns to step S86 and the same processing is repeated. If scanned, the process is terminated.

  As described above, according to the second embodiment, image data output is started before all the originals are read, and image formation is performed by simultaneously writing to and reading from the image memory (reader memory 502). First copy time can be shortened. In addition, it is possible to correct in real time regardless of the size of the original without requiring processing for correcting the inclination and a large-capacity correction memory.

  In the second embodiment, the document fixed reading method is shown. However, the present invention may be applied to a document flow reading method in which an image is read while a document is conveyed using a DF with a scanner unit fixed. Of course. FIG. 22 is a diagram illustrating a state in which writing and outputting of a document image are simultaneously performed in the document scanning method. On the upper side of each of the drawings (A), (B), and (C), the document on the platen glass (symbol d in the figure) and the position of the CCD sensor (symbol e in the figure) are shown. On each lower side of (A), (B), and (C), the read / write state in the image memory (reader memory) is shown. In the figure, time passes from the left figure (A) to the right figure (C). In this case, since the position e of the CCD sensor is fixed, the order stored in the image memory is opposite to that in the case of the fixed reading method. That is, image data is stored from the opposite side in the sub-scanning direction as compared with the fixed reading method. Similarly, when the output data for one vertical line of the document is determined, the output of the image data is started. As described above, by simultaneously writing to and reading from the image memory (reader memory), it is possible to shorten the first copy time when performing image formation.

  The present invention is not limited to the configuration of the above-described embodiment, and can be applied to any configuration that can achieve the functions shown in the claims or the functions of the configuration of the present embodiment. Is possible. For example, in the above embodiment, when the document table glass surface 102 is imaged by the area sensor 300, the document table glass surface 102 is illuminated by the LED 304 in the document detection sensor 401, but instead of using the LED 304, the scanner unit 104. The lamp 103 may be switched so as to illuminate the entire surface of the platen glass surface 102.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above embodiments to a system or apparatus, and the computer (or CPU, MPU, etc.) of the system or apparatus stores the storage medium. It is also achieved by reading out and executing the program code stored in. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

  Examples of storage media for supplying the program code include ROM, floppy (registered trademark) disk, memory card such as PCMCIA card and compact flash (registered trademark), hard disk, micro DAT, magneto-optical disk, CD-R, and the like. You may comprise with optical disks, such as CD-RW, phase change type optical disks, such as DVD. The program code may be downloaded via a network.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) or the like running on the computer is actually executed based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing a part or all of the process and the process is included.

  Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

1 is a diagram illustrating an internal configuration of an image forming apparatus according to a first embodiment. FIG. 2 is a diagram illustrating an appearance of an operation unit (panel) provided in the reader unit 1. 3 is a block diagram showing an electrical configuration of a controller unit 250 in the reader unit 1. FIG. It is a figure which shows image taking-in control when document misalignment arises. 2 is a perspective view showing an appearance of a reader unit 1. FIG. It is a figure which shows typically the mechanism which detects opening and closing of a pressure plate. FIG. 5 is a diagram showing a sub-scanning document misalignment detection line p, a main-scanning document misalignment detection line q, and a detection position set on the platen glass surface. 6 is a graph showing the reading luminance with respect to the opening / closing angle of the pressure plate 403. It is a table which shows the contents of processing performed with respect to each detection position. 6 is a flowchart illustrating a document size detection processing procedure. It is a flowchart which shows the size detection process procedure in step S3, S6, and S7. It is a flowchart which shows the density | concentration determination processing procedure of the deviation | shift detection line pixel in step S18. It is a flowchart which shows the data change detection process procedure of a shift | offset | difference detection line pixel. It is a flowchart which shows the document misalignment measurement processing procedure in step S14. 6 is a flowchart illustrating a document reading operation processing procedure. 2 is a block diagram illustrating a configuration of a controller unit 3 that controls a reader unit 1 and a printer unit 2. FIG. FIG. 6 is a diagram showing a document inclination angle, a size, and a deviation amount from a reference position, calculated from an image of a document on a platen glass surface imaged by an area sensor. It is a figure which shows the scanning range at the time of taking in a document image using a CCD sensor (line sensor). It is a figure which shows a response | compatibility with the original table coordinate in an original table glass surface, and the image memory address in a reader memory. FIG. 4 is a diagram illustrating a state in which document image writing and output are performed simultaneously. 6 is a flowchart illustrating a document reading operation processing procedure. FIG. 4 is a diagram illustrating a state in which writing and outputting of a document image are simultaneously performed in a document scanning method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reader part 2 Printer part 3 Controller part 109 CCD sensor 250 Controller part 300 Area sensor 307,509 ROM
308, 507 CPU
380 Document Abutting Unit 401 Document Detection Sensor 403 Pressure Plate 404 Pressure Plate Open / Close Flag 405 Pressure Plate Open / Close Sensor

Claims (14)

A document reading device that reads an image of a document while scanning the document by a reading unit,
An image pickup means having a two-dimensional image pickup device for picking up an image of a platen on which the original is set before scanning of the reading means;
A document setting state detecting means for detecting a setting state of the document based on the captured image of the document table;
Document size detection means for detecting the size of the document based on the imaged document table;
An original reading apparatus comprising: a reading control unit that controls an image reading operation of the original by the reading unit based on the detected original setting state and original size.   2. The document reading apparatus according to claim 1, wherein the document setting state detecting unit detects a deviation amount in a main scanning direction and a sub scanning direction from a reference position of the document placed on the document table. The document size detecting means includes
Setting means for setting a plurality of detection positions for identifying the size of the document on the document table;
Moving means for moving the set detection positions by an amount of deviation in the detected main scanning direction and sub-scanning direction;
Determining means for determining the presence or absence of a document at each of the plurality of moved detection positions;
3. The document reading apparatus according to claim 2, wherein the size of the document is detected based on the presence or absence of the document at the determined plurality of detection positions. The detection position is set in a two-dimensional region composed of n pixels in the main scanning direction and m pixels in the sub-scanning direction,
A calculation means for calculating an average value of reading values of all pixels constituting the two-dimensional region;
4. The document reading apparatus according to claim 3, wherein the determination unit determines whether or not there is a document at each of the plurality of detection positions based on the calculated average value. Pressure plate means that can freely open and close the document table;
Open / close detecting means for detecting opening / closing of the pressure plate means;
An image of the document table captured by the imaging unit when the pressure plate unit transitions from the open state to the closed state, and an image of the document table captured by the imaging unit when the pressure plate unit reaches the closed state Comparing means for comparing
5. The document reading apparatus according to claim 1, wherein the document size detection unit detects the size of the document based on the comparison result.   The reading control means shifts the deviation amount by the deviation amount when the deviation amount in the main scanning direction and the sub scanning direction from the reference position of the original placed on the original table is detected by the original setting state detection means. 3. The document reading apparatus according to claim 2, wherein an image reading operation of the document by the reading unit is controlled so as to read an image of the document. An original reading method for reading an image of an original while scanning the original with a reading means,
An imaging step of imaging a document table on which the document is set by the imaging unit using a two-dimensional imaging element before the scanning of the reading unit;
A document setting state detecting step for detecting a setting state of the document based on the imaged document table;
A document size detecting step for detecting the size of the document based on the imaged document table;
A document reading method comprising: a reading control step for controlling an image reading operation of the document by the reading unit based on the detected document setting state and document size. A document reading device that reads an image of a document while scanning a document set on a document table by a reading unit,
An image pickup means having a two-dimensional image pickup device for picking up an image of the original table before scanning of the original by the reading means;
A document table image storage means for storing the imaged image of the document table;
Obtaining means for obtaining information relating to a document from the stored image on the platen;
A scanning range determining means for determining a scanning range based on the acquired information on the original;
A selection means for selecting image data of a predetermined range from images read by the reading means while scanning the determined scanning range;
An original reading apparatus comprising: image storage means for storing the selected image data in an image memory.   9. The apparatus according to claim 8, further comprising output means for outputting image data for a predetermined line when image data for a predetermined line is stored in the image memory during scanning of the document by the reading means. Document reader. Conversion means for converting the coordinates of the document table corresponding to the image data selected by the selection means into the address of the image memory;
9. The document reading apparatus according to claim 8, wherein the image storage means stores the image data in accordance with the converted address.   9. The document reading apparatus according to claim 8, wherein the information about the document includes at least one of a deviation amount, a tilt, and a size of the document.   9. The document reading apparatus according to claim 8, wherein the reading unit reads an image having a higher resolution in the main scanning direction and the sub-scanning direction than the imaging unit. 9. The document reading apparatus according to claim 8, further comprising an illuminating unit that illuminates the entire surface of the document table imaged by the imaging unit. A document reading method for reading an image of a document while scanning a document set on a document table by a reading unit,
An imaging step of imaging the document table using a two-dimensional imaging element before starting scanning of the document by the reading unit;
A document table image storage step for storing the imaged document table image;
An acquisition step of acquiring information relating to a document from the stored image on the platen;
A scanning range determination step for determining a scanning range based on the information on the acquired document;
A selection step of selecting a predetermined range of image data from an image read by the reading unit while scanning the determined scanning range;
An original reading method comprising: an image storing step of storing the selected image data in an image memory.

Images