JP4963441B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus, and more particularly to a technique for detecting a document size in an image reading unit.

  Conventionally, in an original reading apparatus, an infrared sensor is used as a method for detecting an original size at the time of reading a book. However, in recent years, there is a method for detecting an original size using an original reading line sensor without using an infrared sensor. It has come to be used. When detecting the document size, not only the main scanning size but also the size in the sub-scanning direction is required. However, when the document size detection in the sub-scanning direction is performed, it is necessary to pre-scan the document surface. This will affect the scanning speed and so on. In practice, the mainstream method is to use the infrared sensor to detect the document size in the sub-scanning direction, and use the line sensor reading data only to detect the main scanning direction. ing.

In all of the patent documents described below, only the main scanning direction is detected. For example, the document size detection apparatus disclosed in Patent Document 1 is a method of determining the document size in the main scanning direction assuming that the inside of the document is white and the outside of the document is black when the pressure plate is opened, but black comes into the document. In the case where the document is jammed, the line sensor reading position is moved, and the size is detected by a white line in the document. For example, the document size detection apparatus disclosed in Patent Document 2 is the same as Patent Document 1 in determining the document size in the main scanning direction, assuming that the inside of the document is white and the outside of the document is black when the platen is opened. The data is taken under two conditions, when the lamp is turned on and when the lamp is extinguished, and the influence of ambient light is excluded. The document size detection device disclosed in Patent Document 3 is the same as that in Patent Document 1 in that the document size in the main scanning direction is determined as white inside the document and black outside the document when the pressure plate is opened. The main scanning document size is detected using the reading data of the line sensor at a plurality of points in the main scanning direction.
JP-A-10-257255 JP 2000-138798 A JP 2003-198809 A

  Patent Documents 1 and 2 are effective in increasing the accuracy of document size detection from two or more types of read data, but do not mention that it is desired to shorten the time until the pressure plate is closed. Further, in Patent Document 3, the time until the pressure plate is closed is short, but it does not mention whether the lamp is lit, and since it is simply averaged in the sub-scanning, the lamp is turned on. / There is a high possibility of malfunction due to the off state.

  In view of the above circumstances, the present invention eliminates the possibility of malfunction due to the on / off state of the lamp, improves the accuracy of document size detection, and shortens the document reading time. It is an object to provide an apparatus and an image forming apparatus equipped with the apparatus.

In order to achieve such an object, the present invention provides a document irradiating unit for irradiating a document, scanning the document with the document irradiating unit to obtain image data of a plurality of lines of the document, and using the image data, Document size detecting means for determining the sub-scan size and determining the document size, document reading means for scanning the document based on the document size determined by the document size detecting means and reading the document image, and for the read document image And calculating means for calculating a difference value of a plurality of patches in a two-dimensional direction read at different times, and a determination means for determining that a document exists if the difference value is equal to or greater than a predetermined value. If the size detection unit fails to determine the document sub-scanning size, the document size detection unit terminates the document size detection operation without determining the document size. Immediately after the size is determined, the scanning direction of the document size detection means reads the document image by scanning the original in the reverse direction, the document size detection means, to perform the determination in the sub-scanning size in the determination contiguous positions, or The determination of the sub-scanning size can be performed at the determination position to be separated, and the determination method performed by the document size detection unit is switched to determination at a continuous determination position or determination at a separation determination position. an image reading apparatus according to claim Rukoto to have a method switching means.

Further, the present invention may be characterized in that, in the above-described image reading apparatus, the determination method switching means performs switching according to a user designation .

Further, the present invention may be characterized in that the image reading apparatus includes a document size notifying unit that notifies the user of the document size determined by the document size detecting unit.

As another aspect, the present invention is an image forming apparatus including the above-described image reading apparatus.

  According to the present invention, an image reading apparatus capable of improving the accuracy of document size detection by eliminating the possibility of malfunction due to the on / off state of the lamp, and reducing the document reading time, and An on-board image forming apparatus is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus irradiates a document 10 placed on a contact glass 1 forming a document surface with light from a lamp 2 and reflects light by a first mirror 3, a second mirror 4, and a third mirror 5. Is condensed by the lens 8 and imaged on the CCD 9. While the lamp 2 and the first mirror 3 travel a distance L, the second mirror 4 and the third mirror 5 travel a distance L / 2. This keeps the optical path length of the optical system constant and scans the entire document.

  FIG. 2 is a perspective view showing a mechanical configuration of the image reading apparatus according to the embodiment of the present invention. The first carriage 6 including the lamp 2 and the first mirror 3 is attached to the drive wire 11, and the second carriage 7 including the second mirror 4 and the third mirror 5 is wound around the pulley 12. . The drive wire 11 is wound around the wire pulley 15 connected to the drive shaft 14, and the drive of the motor 18 is transmitted by the timing pulley 16 and the timing belt 17. A position where a certain distance is returned after one end of the first carriage 6 crosses the home position sensor 13 is defined as a home position.

  FIG. 3 is a hardware configuration diagram of the image forming apparatus in the embodiment of the present invention, and shows an electrical block diagram in a series of image copying operations. When an original is set in the scanner 1001 and the start key is pressed, the original is read by the scanner 1001, a series of image processing is performed in the IPU 1002, image data is output to the printer 1003, and paper is discharged. Necessary parameters in the scanner 1001, the IPU 1002, and the printer 1003 are held in the RAM 1006, and the CPU 1004 sets each device. Further, the mode information necessary for parameter setting is configured so that the user can specify using the operation unit 1005, and the CPU in the operation unit 1005 and the CPU 1004 communicate to exchange information. ing.

  FIG. 4 is a block diagram showing a configuration in the IPU 1002 which is a main component in the embodiment of the present invention. The IPU 1002 performs desired image processing on the document read data received from the scanner 1001. When performing document size detection operation, the image data is stored in a multi-line memory 1012 connected to the image processing module 1011. The IPU 1002 also has a memory control 1013 for controlling the multi-line memory 1012, and the CPU 1004 can read / write the multi-line memory 1012 data.

  FIG. 5 is a flowchart showing a document size detection operation sequence in the embodiment of the present invention. Hereinafter, the document size operation will be described with reference to the flowchart of FIG.

First, the manuscript size detection operation starts when it is detected that the manuscript is placed at the manuscript size detection position and the pressure plate is closed, or when the user starts reading the manuscript. The opening / closing of the pressure plate is detected by ON / OFF of the DF opening / closing sensor. When document size detection is started, first, preparations necessary for document size detection are made (step S1). In this step, setting of document reading timing for document size detection as shown in FIGS. 7 and 8 and preparation setting necessary for shading correction as necessary are executed.

  When preparations necessary for detecting the document size are completed, irradiation of the document is started for reading the document (step S2). In this step, the lamp is turned on. In the flow of FIG. 5, Step S1 and Step S2 are described as being sequentially processed, but there is no particular order, and parallel processing is also possible.

  Next, when the processing of step S1 and step S2 is completed, the original is read (step S3). In this step, a write signal for the document size is generated, image data is read within the valid period of the write signal, and the process ends. At this time, reading may be performed while moving the carriage and scanning the document, or reading may be performed while the carriage is stopped at the document size detection position to acquire read image data of two or more lines. When scanning is performed while moving the carriage and scanning the document, it is possible to read images at different positions on the document, which may cause erroneous detection of the document size depending on the content of the image data on the document. In addition to preventing this, the carriage is moved to the original document reading (main scanning) position in parallel with the reading, so that the time until the start of the main scanning after the document detection can be shortened. On the other hand, if scanning is performed while the carriage is stopped at the document size detection position, it is possible to clearly detect the influence of external light on the document table and changes in the lighting state of the document irradiation lamp from the contents of the image data. (Detection is not impossible even when the carriage is moved).

  Subsequently, when the reading of the original is completed, the irradiation of the original is terminated (step S4). However, in the case where the main scan is started immediately after the reading of the document for size detection is completed, the document irradiation lamp may be kept lit without executing the process of step S4. The flow of FIG. 5 does not describe the process for determining whether to execute the main scan. In addition, the process of step S4 can be performed in parallel with the order of the process of step S5 described below without being defined.

  Then, when the process of step S4 is completed, the read document image data is extracted to analyze the document size (step S5). In the present embodiment, the read document image data is extracted by reading data stored in the multi-line memory 1012 from the CPU 1004 shown in FIG.

  Subsequently, the image data taken out in step S5 is analyzed, and the document size is determined (step S6). Details of the analysis in this step will be described later.

  When the image data is analyzed and the document size is successfully determined (step S6 / YES, step S7), the size with the successful determination is determined as the document size (step S8). Specifically, the determination of the document size is to store the document size information in the RAM 1006 which is a program execution memory connected to the CPU 1004 in FIG. 4, and thereafter, the document size determined as necessary. Read and use information. After the document size is determined, the document size detection operation is completed. On the other hand, if the determination of the document size fails (step S6 / NO), the document size detection operation is completed without determining the document size.

  Examples of document size determination failures include a black document, the influence of external light on the document table, and the illumination state of the document illumination lamp (reading is performed when the lamp is on but the amount of light is not stable) For example, the document size may not be determined from the read data. The basic sequence of the document size detection operation in the present embodiment has been described above.

  Next, analysis of document image data (determination of document size) in step S6 in FIG. 5 will be described in detail. FIG. 6 shows an example of the memory control 1013. The memory controller 1013 receives from the image processing module 1011 the XLSYNC signal that is the reference for one line of the line sensor reading, the PCLK that is the pixel clock, and the XFSYNC signal that indicates the line sensor reading start trigger. Pass the (XWRST) signal and the write enable (XWE) signal. At the same time, the CPU 1004 receives four parameters indicating the memory write area, ie, main scan start, main scan width, sub scan start, and sub scan width, and determines the memory write position from the two reference signals (XFSYNC, XLSYNC).

  FIG. 7 shows the timing in the sub-scanning direction, and FIG. 8 shows the timing in the main scanning direction. By having the above configuration as the memory control, it becomes possible to simultaneously write data of a plurality of patches in the two-dimensional direction as shown in FIG. 9 into the memory (the hatched portion indicates the memory writing area). Although the main scanning direction and the sub-scanning direction are used as parameters and timing, the sub-scanning direction in the present embodiment indicates not only the sub-scanning direction with respect to document reading but also the passage of time. The horizontal axis t in FIG. 9 indicates the passage of time and represents the position of the reading patch at T1 and T2.

  FIG. 10 shows a flow example of image data extraction (step S5) in the flowchart of FIG. The patch data shown in FIG. 9 is read from the plurality of line memories 1012 one by one to the RAM 1006 of the CPU 1004, and an average value of one patch is obtained and binarized, thereby performing monochrome determination of the patch. This will be described with reference to the flowchart of FIG.

  After the monochrome determination flow is started, the number of pixels in one patch is set (step S11). Subsequently, reading is performed from the multi-line memory 1012 in units of one pixel (step S12), and addition is performed (step S13 / NO, step S14) until the read pixel becomes the set N pixel (step S13). Thereafter, an average value in one patch is obtained (step S15), and the binarization of the patch is performed (step S16). The white pixel or black pixel of the patch is determined from the binarization result (step S17, step S18), and the monochrome determination flow is terminated. In FIG. 10, the flow for obtaining the average value is the total average after the total addition of N pixels. For example, the addition in only the main scanning direction is performed to obtain the average for one line, and then the addition and averaging for the next line are repeated. The final determination method may be used, and any flow does not affect the present embodiment.

The above black and white determination will be described in more detail with reference to FIG. The basic algorithm for document size detection is that when the platen is open, the white part of the document is white (reflected light is reflected), and the non-documented part outside the document is black (no reflected light). Is used. That is, in FIG. 11, it is determined that there is a document that is brighter than TH and that there is no document when it is darker than TH. However, as shown in FIG. 11, in the case of a document having a dark background density, TH is not exceeded even if the inside of the document is read, and it is erroneously determined that there is no document. To prevent this, as in step S16 of FIG. 10, patches read at times T1 and T2 are set as PAT1 and PAT2, and a difference value between PAT1 and PAT2 is obtained. If there is a difference of ΔD or more, TH is exceeded. Even if there is no document, it is determined that there is a manuscript. As shown in FIG. 6, as a parameter setting from the CPU 1004, ΔD setting is added in addition to the start / width in the main scanning direction and the start / width in the sub scanning direction.

  Next, the image data analysis (step S6) in the flowchart of FIG. 5 will be described in more detail with reference to FIG. As a reading patch, L (n) IN and L (n) JUDGE are used as shown in FIG. N in L (n) indicates the number of times of reading since the start of line sensor reading (indicating the passage of time), IN and JUDGE indicate positions in the main scanning direction, and IN is related to the type of document to be detected. Rather, the main scanning position where all the documents enter the document is shown, and JUDGE indicates the main scanning position where the document is switched inside / outside the document.

  After starting the detection flow, first, the number of detections N is set, and n = 1 is set as an initial value (step S21). Then, it is determined whether or not n exceeds the number of detections (step S22). If n is equal to or less than the set number of detections N (step S22 / YES), it is determined whether L (n) IN is white (step S22). S23). When L (n) IN is not white (step S23 / NO), it is determined that the inside of the document is black and the lamp is off, and n = n + 1 is set (step S24), and the comparison with the number of detections N is performed again (step S22). If this is repeated and L (n) IN does not become white and n exceeds N (step S22 / NO), it is determined that detection is impossible and the detection flow is exited (step S25).

  If the determination result is white in the determination of Ln (IN) (step s23 / YES), the determination result of L (n) JUDGE is set as a detection candidate (step S26). Subsequently, the detection candidate obtained is incremented by 1 (n = n + 1) (step S27), and the next reading result is determined, that is, whether L (n) JUDGE is black (step S28). If L (n) JUDGE is white (step S28 / NO), there is a high possibility that the pressure plate has been closed. Therefore, the determination is not made here and the result of the previous detection candidate is used as it is. In other words, n = n−1 is set (step S30), and the determination result of L (n) JUDGE to which n is substituted is set as a detection candidate (step S29). On the other hand, if L (n) JUDGE is black (step S28 / YES), it is considered that the lamp is more stable than the previous time, so that the current determination result is used (step S29). Then, the document size detection flow ends.

  The basic sequence and algorithm relating to document size detection in the present embodiment have been described above with reference to FIGS. 5 to 12. An example flow of document size detection will now be described as an example.

[Example 1]
FIG. 13 is a flow chart showing a series of document size detection operations in the first embodiment. In this embodiment, the size detection operation is performed when the document size detection positions are continuous.

  When a trigger event for starting the document size detection (pressure plate closing or reading start by the user) occurs, the document size detection operation is started. After the start of the document size detection operation, preparations necessary for document size detection are made (step S101). In this step, setting of document reading timing for document size detection as shown in FIGS. 7 and 8 and preparation setting necessary for shading correction as necessary are executed. Further, irradiation of the original is started here for reading the original. After making preparations necessary for detecting the document size, the carriage starts to be driven in the forward direction (step S102). In FIG. 13, step S101 and step S102 are described as being sequentially processed, but the operation of step S101 ends until the carriage reaches the document leading edge position (or the sub-scan document size detection start position). If so, the order is not particularly specified, and parallel processing is also possible.

  Subsequently, after the carriage is driven, reading of the document is started (step S103). The document reading is performed by reading image data of a certain number of lines or more. At this time, the carriage is moving in the forward direction. Then, when the image data of a predetermined number of lines or more is acquired by reading the document, the read document image data is taken out in order to analyze the document size (step S104). In this embodiment, the read document image data is extracted by reading data stored in the multi-line memory 1012 from the CPU 1004 in FIG.

  Next, the extracted image data is analyzed (step S105), and the presence / absence of a document is determined (step S106). Here, an object for analyzing image data is a region at a specific position in the main scanning direction. This corresponds to one of the detection positions shown in FIG. When it is determined that there is no original in the determination of the presence / absence of the original (step S106 / NO), the original size is determined (step S107). Specifically, the determination of the document size is to store the document size information in the RAM 1006 which is a program execution memory connected to the CPU 1004 in FIG. 4, and thereafter, the document size determined as necessary. Read and use information. On the other hand, when it is determined that there is a document (step S106 / YES), the document is read and image data is acquired again (step S103).

  After the document size is determined, the carriage is driven in the direction opposite to the direction scanned by size detection (step S108), and the original scan of the document is started (step S109). In the document scanning operation, the carriage reaches the leading edge of the document (starting scanning for size detection from the trailing edge of the document and reading in the opposite direction, so the leading edge of the document is the final scan position of the main scan). (Step S110 / NO). After reaching the trailing edge of the document (step S110 / YES), the document size detection operation is completed (step S111). The completion of the document size detection operation specifically includes stop of carriage drive, end of lamp irradiation, post-processing, and the like. With the above operation, the document size detection operation and the main scanning operation are completed.

  If the extracted image data is not analyzed and the document size determination fails (step S105 / NO), the document size detection operation is completed without determining the document size (step S111). Examples of document size determination failures include a black document, the influence of external light on the document table, and the illumination state of the document illumination lamp (reading is performed when the lamp is on but the amount of light is not stable) For example, the size of the document cannot be determined from the read data.

[Example 2]
FIG. 15 is a flowchart showing a series of document size detection operations in the second embodiment. In the first embodiment, the size detection is performed when the document size detection positions are continuous, but in this embodiment, the size detection operation is performed when the detection positions are separated from each other.

  When a trigger event for starting the document size detection (pressure plate closing or reading start by the user) occurs, the document size detection operation is started. After starting the document size detection operation, preparations necessary for document size detection are made (step S201). Preparations necessary for document size detection are the same as those in the first embodiment. Further, irradiation of the original is started here for reading the original. After making necessary preparations for document size detection, the carriage is started to be driven in the forward direction (step S202). As for the processing in step S201 and step S202, as in the first embodiment, if the operation of step S201 is completed before the carriage reaches the document leading edge position (or the subscanning document size detection start position). There is no particular order, and parallel processing is also possible.

  Then, until the carriage reaches a predetermined document size detection position (step S203 / NO), it waits for reading of the document. As shown in FIG. 14, the predetermined document size detection position is set to a position where the standard document size can be determined, and corresponds to the positions A, B, and C among the detection positions in FIG. To do. Then, after reaching the detection position (step S203 / YES), reading of the document is started (step S204). The document reading is performed by reading image data of a certain number of lines or more. At this time, the carriage moves in the forward direction. Subsequently, when the image data of a predetermined number of lines or more is acquired by reading the document, the read document image data is taken out in order to analyze the document size (step S205). In this embodiment, the read document image data is extracted by reading data stored in the multi-line memory 1012 from the CPU 1004 in FIG.

  Next, the extracted image data is analyzed (step S206), and the presence / absence of a document is determined (step S207). Here, an object for analyzing image data is a region at a specific position in the main scanning direction. This corresponds to one of the detection positions shown in FIG. If it is determined that there is no document (NO in step S207), the document size is determined (step S208), and if it is determined that there is a document (YES in step S207). Reads the document and obtains the image data again (step S204). The specific operation for determining the document size is the same as in the first embodiment.

  After the document size is determined, the carriage is driven in the direction opposite to the direction scanned by size detection (step S209), and the original scan of the document is started (step S210). In the document scanning operation, the carriage reaches the leading edge of the document (starting scanning for size detection from the trailing edge of the document and reading in the opposite direction, so the leading edge of the document is the final scan position of the main scan). (Step S211 / NO). After reaching the trailing edge of the document (step S211 / YES), the document size detection operation is completed (step S212). On the other hand, when the extracted image data is not analyzed and determination of the document size fails (step S206 / NO), the document size detection operation is completed without determining the document size (step S212). An example in which the document size detection operation is completed or the document size determination fails is the same as in the first embodiment.

[Example 3]
FIG. 16 is a flowchart showing a series of document size detection operations in the third embodiment. Example 1 is a size detection operation when the document size detection positions are continuous (hereinafter referred to as continuous size detection operation), and Example 2 is a size detection operation when the detection positions are separated (hereinafter referred to as separation). In this embodiment, one of the two size detection operation methods is selected based on the user setting to detect the document size.

  First, a user inputs in advance from the operation panel a document size detection method such as whether to perform a continuous size detection operation or a separation size detection operation. The input set value is stored in the nonvolatile RAM. When a trigger event for starting document size detection (press plate closing or reading start by the user) occurs, the document size detection operation is started. After the start of the document size detection operation, preparations necessary for document size detection are made (step S301). Preparations necessary for document size detection are the same as those in the first and second embodiments. Further, irradiation of the original is started here for reading the original. After making preparations necessary for detecting the document size, the carriage starts to be driven in the forward direction (step S302). As for the processing in step S301 and step S302, as in the first and second embodiments, the operation in step S301 ends until the carriage reaches the document leading edge position (or the subscanning document size detection start position). If so, the order is not particularly specified, and parallel processing is also possible.

  Then, referring to a preset document size detection method, it is confirmed whether the operation is a discrete size detection operation or a continuous size detection operation (step S303). If it is a discrete size detection operation (step S303 / YES), the document size detection position is determined (step S304), and if it is a continuous size detection operation (step S303 / NO), document reading is performed (step S305). In the determination of the document size detection position, reading of the document is waited until the carriage reaches a predetermined document size detection position (NO in step S304). The predetermined document size detection position is the same as that in the second embodiment. Then, after reaching the detection position (step S304 / YES), reading of the document is started (step S305). The document reading is performed by reading image data of a certain number of lines or more. At this time, the carriage moves in the forward direction. Subsequently, when the image data of a predetermined number of lines or more is acquired by reading the document, the read document image data is extracted to analyze the document size (step S306). The specific operation for extracting document image data is the same as that in the first and second embodiments.

  Next, the extracted image data is analyzed (step S307), and the presence / absence of a document is determined (step S308). If it is determined that there is no document (NO in step S308), the document size is determined (step S309), and if it is determined that there is a document (YES in step S308). Reads the document and acquires the image data again (step S305). Note that the specific object of image data analysis and document size determination are the same as in the first and second embodiments. After the document size is determined, the carriage is driven in the direction opposite to the direction scanned by size detection (step S310), and the original scan of the document is started (step S311). In the document scanning operation, the carriage reaches the leading edge of the document (starting scanning for size detection from the trailing edge of the document and reading in the opposite direction, so the leading edge of the document is the final scan position of the main scan). (Step S312 / NO). After reaching the trailing edge of the document (step S312 / YES), the document size detection operation is completed (step S313). On the other hand, when the extracted image data is not analyzed and determination of the document size fails (step S307 / NO), the document size detection operation is completed without determining the document size (step S313). An example in which the document size detection operation is completed or the document size determination fails is the same as in the first and second embodiments.

  It should be noted that the determined document size may be displayed on the operation panel in the flowchart of a series of operations in the first to third embodiments. The display size can be displayed in a standard document size (A4 portrait, A3 landscape, etc.) or in a length actually detected (297 mm × 420 mm, etc.).

  The above-described embodiment is a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention to the above-described embodiment alone, but in a form in which various modifications are made without departing from the gist of the present invention. Implementation is possible.

  That is, the image reading apparatus in the above-described embodiment operates by processing, means, and functions executed by a computer according to program instructions. The program sends a command to each component of the computer, extracts the image data of the read original by the predetermined processing and functions as described above, for example, the IPU, analyzes it, and sets the original size based on the analysis result. When the detection is successful, the document size is determined. When the detection is unsuccessful, the detection operation is terminated without determining the document size, and the CPU moves the carriage in the direction opposite to the scanning for size detection immediately after the document size is detected. A process for driving the scanner to start a main scan of the document is performed. As described above, the processes and means in the above-described embodiment are realized by specific means in which the program and the computer cooperate.

  Then, for example, a computer (CPU) of the image reading apparatus stores the program code stored in the storage medium via a computer-readable recording medium that records the program code of the software that realizes the functions of the above-described embodiment, that is, the storage medium. The object of the present invention is also achieved by executing the reading. Further, the program can be loaded and executed directly on a computer through a communication line without going through a recording medium, and the object of the present invention can be achieved similarly.

  In this case, the program code itself read from the storage medium or loaded and executed through the communication line realizes the functions of the above-described embodiment. And the storage medium which memorize | stored the program code comprises this invention.

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a nonvolatile memory card, a ROM, and a magnetic tape. Can be used.

  According to the embodiment described above, it is possible to shorten the document reading time by starting a main scan of a document immediately after the document size is determined. In addition, when the size detection fails, the detection operation is terminated without determining the document size, thereby eliminating the possibility of malfunction due to the on / off state of the lamp and improving the accuracy of the document size detection. .

  Further, according to the above-described embodiment, it is possible to detect the document size more accurately by continuously determining the document size with respect to the document size detection position.

  Further, according to the above-described embodiment, the data processing amount is greatly reduced by discretely determining the document size with respect to the detection position of the document size, so that the processing time can be shortened. As a result, the carriage speed can be increased as compared with the continuous determination, and as a result, it can be expected that the time during which the pressure plate is opened (the time during which the size is determined) is shortened.

  Further, according to the above-described embodiment, an image having both merits can be obtained by appropriately selecting an operation for the purpose of accurate size detection or an operation for the purpose of shortening the processing time. A reading device can be provided.

  In addition, according to the above-described embodiment, it is possible to select a document size detection method according to user settings, and to notify the user of a detailed document size, so that a highly convenient image that meets the user's needs. A reading device can be provided.

1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating a mechanical configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a hardware configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a hardware configuration diagram of an image forming apparatus according to an embodiment of the present invention. 5 is a flowchart showing a flow of a document size detection operation in the embodiment of the present invention. FIG. 5 is a diagram for explaining analysis of document image data in the embodiment of the present invention, and illustrates an operation of memory control. FIG. 6 is a diagram for explaining analysis of document image data in the embodiment of the present invention, and illustrates a timing chart in the sub-scanning direction. FIG. 5 is a diagram for explaining analysis of document image data in the embodiment of the present invention, and illustrates a timing chart in the main scanning direction. FIG. 5 is a diagram for explaining analysis of document image data in the embodiment of the present invention and represents a memory writing area. It is the flowchart which showed the flow of the monochrome determination operation | movement in embodiment of this invention. It is a figure for demonstrating the black-and-white determination in embodiment of this invention. 6 is a flowchart showing a flow of an original image data analysis operation in the embodiment of the present invention. 6 is a flowchart showing a flow of a document size detection operation and a document reading operation in the embodiment of the present invention. FIG. 5 is a diagram for explaining a document size detection position in the embodiment of the present invention. 6 is a flowchart showing a flow of a document size detection operation and a document reading operation in the embodiment of the present invention. 6 is a flowchart showing a flow of a document size detection operation and a document reading operation in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact glass 2 Lamp 3 1st mirror 4 2nd mirror 5 3rd mirror 6 1st carriage 7 2nd carriage 8 Lens 9 CCD
DESCRIPTION OF SYMBOLS 10 Document 11 Drive wire 12 Pulley 13 Home position sensor 14 Drive shaft 15 Wire pulley 16 Timing pulley 17 Timing belt 18 Motor 1001 Scanner 1002 IPU
1003 Printer 1004 CPU
1005 Operation unit 1006 RAM
1011 Image processing module 1012 Multiple line memory 1013 Memory control

Claims (4)

A document irradiation means for irradiating a document;
A document size detecting unit that scans the document by the document irradiation unit to acquire image data of a plurality of lines of the document, determines a sub-scanning size of the document by using the image data, and determines a document size;
A document reading unit that scans the document based on the document size determined by the document size detection unit and reads a document image;
Calculating means for calculating a difference value of a plurality of patches in two-dimensional directions read at different times with respect to the read document image;
Determining means for determining that the document exists when the difference value is equal to or greater than a predetermined value;
The document size detection means ends the document size detection operation without determining the document size when the determination of the sub-scanning size of the document fails.
The document reading unit scans the document in a direction opposite to the scanning direction of the document size detection unit immediately after the document size is determined by the document size detection unit, and reads a document image.
The document size detection unit is configured to be able to determine the sub-scanning size at consecutive determination positions, or to determine the sub-scanning size at determination positions that are separated from each other.
An image reading apparatus comprising: a determination method switching unit that switches a determination method performed by the document size detection unit to determination at the continuous determination position or determination at the separated determination position. The image reading apparatus according to claim 1 , wherein the determination method switching unit performs switching according to a user designation.   The image reading apparatus according to claim 1, further comprising a document size notifying unit that notifies a user of a document size determined by the document size detecting unit.   An image forming apparatus comprising the image reading apparatus according to claim 1.

Images