JP2010251917A - Image read/storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image read/storage device capable of preventing a space capacity of a page memory from becoming insufficient during document read, and can use the page memory efficiently. <P>SOLUTION: The image read/storage device includes: an image read section for optically reading each conveyed document; an image data generation section for generating the image data of each document that has been read; a page memory control section for successively writing the generated image data to the page memory; and a compression encoding section for compressing and encoding the image data read from the page memory. The page memory control section determines whether each of a plurality of logic pages obtained by logically dividing a storage region of the page memory is in an empty state, and prohibits starting to convey the document when there are no logic pages in an empty state. The plurality of logic pages include logic pages including a storage capacity smaller than the maximum capacity of the image data that can be generated by the image data generation section. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image reading and storage device provided in a scanner device, a copier, a facsimile machine, a multi function peripheral (MFP), and the like.

  There are scanner devices, copiers, facsimile machines, multifunction devices, and the like that include an image reading storage device that temporarily stores image data obtained by reading a document in a page memory before compression encoding. In such an image reading storage device, when the reading speed of the original is low, the possibility that the free space of the page memory is insufficient when reading the original is extremely low. Therefore, when the reading speed of the original is low, the image reading storage device starts reading the original without checking the free space in the page memory.

  However, in an image reading and storage device equipped with an ADF (Auto Document Feeder) that automatically and sequentially feeds a plurality of documents placed on a document supply tray one by one, a plurality of documents are successively received. Since reading is performed at high speed, there is a high possibility that the page memory has insufficient free space during reading. When the free space of the page memory becomes insufficient during the reading of the document, the image reading and storing device has to interrupt the reading of the document. When such reading interruption occurs, an unnatural boundary or the like occurs between an image showing a part of the original read before interruption and an image showing a part of the original read after interruption.

  Therefore, conventionally, an image reading and storage device has been proposed in which it is confirmed that a free space for storing image data exists in the page memory before the conveyance of each document is started. A conventional image reading and storing device divides a page memory into logical pages having a storage capacity equal to or larger than the maximum capacity of image data, and manages the free state for each logical page. Therefore, the conventional image storage device has a free space in the page memory for storing image data by checking whether or not there is an empty logical page before starting to convey each document. You can easily check what you want to do. Then, since the conveyance of the original is started after checking the free space of the page memory in this way, the conventional image reading and storing device can prevent the free space of the page memory from being insufficient during the reading of the original.

  There has also been proposed an image reading and storage device that monitors the free space of an image memory that temporarily stores a code string generated by compressing and encoding image data when reading a document (for example, Patent Documents). 1).

JP 2005-167727 A

  However, the conventional image reading and storing device has a problem that waste is increased when the size of the original to be read is smaller than the maximum size in order to secure the maximum capacity of the image data.

  Accordingly, the present invention has been made in order to solve the above-described problems, and prevents an insufficient free space in the page memory during reading of an original, and allows the page memory to be used efficiently. An object is to provide an apparatus.

  In order to achieve the above object, an image reading and storing apparatus according to the present invention includes a document transport unit that sequentially transports a plurality of documents placed on a mounting table one by one, and each of the document transport units transported by the document transport unit. An image reading unit that optically reads a document, an image data generation unit that generates image data of each document read by the image reading unit, a page memory that temporarily stores the image data, and the page memory A page memory control unit that controls as a ring buffer, sequentially writes the image data generated by the image data generation unit to the page memory, and reads the image data stored in the page memory via the page memory control unit, A compression encoding unit that generates a code string by compressing the read image data; and a code generated by the compression encoding unit. The page memory control unit stores data that has not yet been read for each of a plurality of logical pages obtained by logically dividing the storage area of the page memory. It is determined whether or not there is a free logical page, and when there is no free logical page, the start of conveyance of the document is prohibited, and the plurality of logical pages are images that can be generated by the image data generation unit. Includes logical pages that have a storage capacity that is less than the maximum capacity of the data.

  As a result, the page memory can be controlled using a logical page having a capacity smaller than the capacity corresponding to the maximum size original that can be read. It is not always necessary to ensure. Therefore, the page memory can be used efficiently. Further, since it is possible to prohibit the start of document conveyance when there is no empty logical page, it is possible to easily prevent the page memory from being insufficient during reading of the document.

  The page memory control unit further includes a sensor unit that detects the size of the document placed on the mounting table, and the page memory control unit further outputs the image data being written when there is a free logical page. To obtain a write pointer indicating the position to write to, and a read pointer indicating the position to read the image data being read next, using the acquired write pointer and read pointer, to calculate the free capacity of the page memory, When the calculated available capacity is equal to or larger than the image data capacity corresponding to the size of the document detected by the sensor unit, the start of conveyance of the document is permitted, and the calculated available capacity is detected by the sensor unit. When the image data capacity is smaller than the size of the original document, it is preferable to prohibit the start of conveyance of the original document.

  As a result, when there is an empty logical page, permission or prohibition of the start of document conveyance is determined using the calculated actual available capacity, so that there is not enough available page memory during document reading. Can be prevented.

  Further, the page memory control unit waits for the end of the writing of the image data, determines whether to start reading the image data, waits for the end of the writing of the image data, When starting to read data, the size of the original detected by the sensor unit is used to estimate the address where the writing of the image data is scheduled to end, and the address indicated by the acquired write pointer is set to the estimated address. It is preferable to change.

  Thus, it is possible to appropriately calculate the free space of the page memory depending on whether the reading of the image data is started after the writing of the image data is completed. Therefore, even when the reading of the image data is started after completion of the writing of the image data, it is possible to prevent the page memory from being insufficient in the middle of reading the document.

  In addition, the present invention can be realized not only as such an image reading and storing apparatus, but also as an image reading and storing method in which operations of characteristic components included in such an image reading and storing apparatus are used as steps. Can do. Further, the steps included in such an image reading and storing method can be realized as a program for causing a computer to execute the steps. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

  As is apparent from the above description, the image reading and storing apparatus according to the present invention can control the page memory using a logical page having a capacity smaller than the capacity of image data corresponding to the maximum-size document. Therefore, it is not necessary for the image reading storage device to always ensure the capacity of image data corresponding to the maximum size document before reading the document, and the page memory can be used efficiently.

1 is an external view of a multi-function peripheral including an image reading and storing device according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a main mechanical configuration of an image reading and storage device according to an embodiment of the present invention. 1 is a block diagram illustrating a characteristic functional configuration of a multifunction peripheral including an image reading and storing device according to an embodiment of the present invention. It is a figure for demonstrating the page memory with which the image reading storage treatment which concerns on embodiment of this invention is provided. It is a flowchart which shows the operation | movement of the image reading memory | storage treatment which concerns on embodiment of this invention. 4 is a flowchart showing details of the operation of the image reading and storing apparatus according to the embodiment of the present invention. 4 is a flowchart showing details of the operation of the image reading and storing apparatus according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. Here, a multi-function machine including the image reading and storage device according to the present invention will be described as an example.

  FIG. 1 is an external view of a multifunction machine 1 including an image reading and storage device 17 according to an embodiment of the present invention.

  The multifunction device 1 has printer, facsimile, and scanner functions. For example, the multifunction device 1 generates a code string by optically reading the document 50, and copies an image indicated by the generated code string to a paper medium different from the document 50. As shown in FIG. 1, the multifunction machine 1 includes an operation panel 15, a display 16, and an image reading storage device 17.

  The operation panel 15 is a panel that receives an operation from the user. The operation panel 15 rotates the image data after reading by a predetermined angle (such as 90 degrees, 180 degrees, or 270 degrees), and accepts an instruction to print, facsimile transmission, or store the rotated image data in a recording medium.

  The display 16 is a liquid crystal display (LCD) or the like, and is used for interaction with the user. The display 16 displays the operating state of the multifunction device 1.

  The image reading storage device 17 is a device that generates a code string by optically reading a document to be transmitted by facsimile or output to a printer, and stores the generated code string. Note that the image reading storage device 17 according to the present embodiment can read color originals up to “A3 size”.

  FIG. 2 is a cross-sectional view showing a main mechanical configuration of the image reading and storing device 17 incorporated in the multifunction machine 1 shown in FIG. As shown in FIG. 2, the image reading storage device 17 includes an ADF unit 21 and an image reading unit 22.

  The ADF unit 21 includes a sensor unit 45, a document supply tray 52, which is an example of a placement table, a document transport unit 53, and a document discharge tray 64.

  The sensor unit 45 includes a length sensor 46 and a width sensor 47, and detects the size of the document 50 placed on the document supply tray 52. Specifically, the length sensor 46 detects the size in the length direction (X direction) of the document 50 placed on the document supply tray 52. The width sensor 47 detects the size of the document 50 placed on the document supply tray 52 in the width direction (Y direction).

  The document transport unit 53 includes transport rollers 54, 58, and 60 and driving means (not shown), and sequentially transports a plurality of documents 50 placed on the document supply tray 52 one by one. Specifically, a plurality of documents 50 placed on the document supply tray 52 are carried into the conveyance path 56 one by one by a conveyance roller 54 rotated by a driving unit. Each document 50 carried into the conveyance path 56 is conveyed to the document discharge tray 64 by a plurality of conveyance rollers 58 and 60 arranged along the conveyance path 56.

  The image reading unit 22 optically reads the surface of each document 50 conveyed along the conveyance path 56 by the document conveying unit 53. Here, the surface of the original 50 indicates the upper surface of the original 50 placed on the original supply tray 52. The image reading unit 22 includes a scanning unit 79, a second mirror 83 and a third mirror 85, an optical lens 87, and a photoelectric conversion element 89.

  The scanning unit 79 includes a light source 80 and a first mirror 81. The light source 80 is, for example, an LED (Light Emitting Diode), and an original that comes in contact with the translucent contact glass 76 when the original 50 being conveyed through the conveyance path 56 by the original conveying unit 53 passes through the reading slit 77. 50 surfaces are irradiated with light. The first mirror 81 deflects the reflected light from the surface of the document 50 that passes through the reading slit 77 in the direction of the second mirror 83.

  The optical lens 87 forms an image of the reflected light from the surface of the document 50 received through the first mirror 81, the second mirror 83, and the third mirror 85 on the light receiving surface of the photoelectric conversion element 89.

  The photoelectric conversion element 89 is a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, for example, and reads the surface of the document 50 by converting the light received on the light receiving surface into an electric signal.

  Further, the image reading unit 22 can optically read the surface of the document 50 placed on the contact glass 76. In that case, the scanning unit 79 scans the document 50 placed on the contact glass 76. Specifically, the scanning unit 79 irradiates the surface of the document 50 placed on the contact glass 76 while moving in the positive direction of the X axis, and secondly reflects light from the surface of the document 50. Deflection in the direction of the mirror 83.

  FIG. 3 is a block diagram showing a characteristic functional configuration of the multi-function device 1 including the image reading and storing device 17 according to the embodiment of the present invention. That is, FIG. 3 is a block diagram showing functions related to the present invention among the functions of the multifunction device 1.

  The image data generation unit 111, the page memory control unit 112, the page memory 113, and the compression encoding unit 114 are components realized by, for example, an integrated circuit mounted on a board provided in the vicinity of the image reading unit 22. is there. In addition, the image memory control unit 131, the image memory 132, and the image processing unit 133 are components realized by, for example, an integrated circuit mounted on a main board provided at the center position of the main body of the multifunction machine 1 or the like.

  The image data generation unit 111 generates image data of each document 50 optically read by the image reading unit 22. Specifically, the image data generation unit 111 acquires an electrical signal indicating an image of the surface of the document 50 conveyed along the conveyance path 56 from the photoelectric conversion element 89. Then, the image data generation unit 111 generates image data by sequentially A / D converting the electrical signal acquired from the photoelectric conversion element 89.

  The page memory control unit 112 controls data transfer with the page memory 113. Specifically, the page memory control unit 112 writes the image data generated by the image data generation unit 111 into the page memory 113. Further, the page memory control unit 112 reads the image data stored in the page memory 113 in response to the request from the compression encoding unit 114.

  Here, the page memory control unit 112 controls the page memory 113 as a ring buffer. Specifically, the page memory control unit 112 moves the write pointer to the page memory start address when the write pointer indicating the position to write data next reaches the page memory end address. Here, the page memory head address is an address indicating the head position of the storage area of the page memory 113. The page memory end address is an address indicating the end position of the storage area of the page memory 113.

  Further, the page memory control unit 112 manages whether or not each of the plurality of logical pages obtained by logically dividing the storage area of the page memory 113 is in an empty state in which unread data is not stored. . Here, the plurality of logical pages include logical pages having a storage capacity smaller than the maximum capacity of image data that can be generated by the image data generation unit 111. Specifically, the plurality of logical pages include logical pages having a capacity of image data corresponding to a document (for example, “A4 size”) smaller than “A3 size” which is the maximum size of a readable document. included. The unread data indicates data that has not yet been read out of the data written in the page memory 113.

  Further, the page memory control unit 112 determines whether or not there is an empty logical page before the document conveying unit 53 starts conveying each document 50. Here, when there is no empty logical page, the page memory control unit 112 prohibits the start of conveyance of the document 50.

  On the other hand, when there is a free logical page, the page memory control unit 112 acquires the write pointer and the read pointer, and calculates the free capacity of the page memory using the acquired write pointer and read pointer. Here, when the calculated available capacity is equal to or larger than the image data capacity corresponding to the size of the document 50 detected by the sensor unit 45, the page memory control unit 112 permits the start of conveyance of the document 50. On the other hand, when the calculated available capacity is smaller than the image data capacity corresponding to the size of the document 50 detected by the sensor unit 45, the page memory control unit 112 prohibits the start of conveyance of the document 50.

  The page memory 113 is a readable / writable memory having a volatile storage area in which image data generated by the image data generation unit 111 is temporarily stored. In the page memory 113, it is managed whether or not each of the plurality of logical pages obtained by logically dividing the storage area is free.

  The compression encoding unit 114 generates a code string by compressing and encoding the image data read from the page memory 113 by the page memory control unit 112 according to a compression encoding method such as JPEG or JBIG.

  The image memory control unit 131 controls data transfer with the image memory 132. Specifically, the image memory control unit 131 writes the code string generated by the compression encoding unit 114 in the image memory 132. Further, the image memory control unit 131 reads out the code string stored in the image memory 132 in response to a request from the image processing unit 133.

  The image memory 132 is a readable / writable memory having a volatile storage area or the like for temporarily storing the code string generated by the compression encoding unit 114.

  The image processing unit 133 decodes the code string read from the image memory 132 by the image memory control unit 131, and performs enlargement, reduction, or smoothing of the image indicated by the decoded image data. Further, the image processing unit 133 outputs the decoded image data to the modem 13 or the printer 18.

  The modem 13 is a fax modem that modulates image data transmitted by facsimile or demodulates image data transmitted from the outside by facsimile. Specifically, the modem 13 modulates the image data output by the image processing unit 133, for example.

  The printer 18 is a printing device, and prints the image data output by the image processing unit 133. The printer 18 prints image data transmitted from another facsimile apparatus or the like via a PSTN (Public Switched Telephony Networks).

  FIG. 4 is a diagram for explaining the page memory 113 provided in the image reading and storing device 17 according to the embodiment of the present invention.

  As shown in FIG. 4, the storage area 140 of the page memory 113 is logically divided into four logical pages: a first logical page 141, a second logical page 142, a third logical page 143, and a fourth logical page 144. ing. In the present embodiment, the first logical page 141, the second logical page 142, the third logical page 143, and the fourth logical page 144 are equally divided so as to have the same storage capacity.

  Specifically, in the present embodiment, since the page memory 113 has a storage capacity for 2.4 pages of “A3 size” originals, each logical page is 0.8 of an “A3 size” original. It has a storage capacity for pages. That is, each logical page has a storage capacity smaller than the maximum capacity of image data (capacity of image data corresponding to “A3 size”) that can be generated by the image data generation unit 111.

  In the image reading storage device 17 according to the present invention, the page memory 113 is not necessarily divided into four. Further, the page memory 113 need not be divided equally. For example, the page memory 113 may be composed of five logical pages having different capacities. That is, it is only necessary that a plurality of logical pages include a logical page having a storage capacity smaller than the maximum capacity of image data that can be generated by the image data generation unit 111.

  In FIG. 4, the black triangle symbol indicates the write pointer 145, and the white triangle symbol indicates the read pointer 146. The write pointer 145 indicates the position to write data next, and proceeds in the direction of the arrow in the figure. When the write pointer 145 advances to the right end (page memory end address) of the storage area, the write pointer 145 moves to the left end (page memory start address) of the storage area. The read pointer 146 indicates the position where data is read next, and the read pointer 145 cannot be overtaken.

  A hatched area between the read pointer 146 and the write pointer 145 indicates an area in the page memory 113 in which unread data is stored. In the case of the page memory 113 shown in FIG. 4, the fourth logical page 144 is managed as being free. Further, the first logical page 141, the second logical page 142, and the third logical page 143 are managed so as not to be free.

  More specifically, the page memory control unit 112 manages the first logical page 141 as being in a read state. Here, the read state is a state in which the read pointer 146 indicates an address in the logical page. The third logical page 143 is managed by the page memory control unit 112 as being in a write state. Here, the write state is a state in which the write pointer 145 indicates an address in the logical page.

  Next, various operations in the MFP 1 configured as described above will be described.

  FIG. 5 is a flowchart showing the operation of the image reading and storing apparatus 17 according to the embodiment of the present invention.

  First, the sensor unit 45 detects the size of the document 50 to be transported from among the plurality of documents 50 placed on the document supply tray 52 (step S101). Specifically, the length sensor 46 detects the length of the document 50, and the width sensor 47 detects the width of the document 50.

  Subsequently, the document conveyance unit 53 inquires of the page memory control unit 112 whether or not the conveyance of the document 50 placed on the document supply tray 52 may be started (step S102). Therefore, the page memory control unit 112 determines whether there is a free logical page (step S103). For example, when the page memory 113 is in the state shown in FIG. 4, the page memory control unit 112 determines that there is a free logical page because the fourth logical page 144 is free.

  Here, when there is no empty logical page (No in step S103), the page memory control unit 112 prohibits the document conveying unit 53 from starting the conveyance of the document 50 (step S104), and the process of step S102 is performed. Return.

  On the other hand, when there is a free logical page (Yes in step S103), the page memory control unit 112 calculates the free capacity of the page memory (step S105). Details of the calculation of the free space by the page memory control unit 112 will be described later with reference to FIGS.

  Next, the page memory control unit 112 calculates the volume of image data corresponding to the size of the document 50 detected by the sensor unit 45 (step S106). Specifically, the page memory control unit 112 calculates, for example, the number of pixels in the width direction (hereinafter simply referred to as “number of pixels”) from the width of the document 50 detected by the width sensor 47 and the reading resolution. Further, the page memory control unit 112 calculates the number of lines from the length of the document 50 detected by the length sensor 46 and the reading resolution. Then, the page memory control unit 112 calculates the volume of image data corresponding to the size of the document 50 detected by the sensor unit 45 by multiplying the product of the number of pixels and lines calculated in this way and the data capacity per pixel. Calculate as

  Subsequently, the page memory control unit 112 determines whether or not the free space calculated in step S105 is equal to or larger than the image data capacity calculated in step S106 (step S107). If the free capacity is smaller than the image data capacity (No in step S107), the page memory control unit 112 prohibits the start of conveyance of the document 50 by the document conveyance unit 53 (step S104), and the process of step S102. Return to.

  On the other hand, when the free capacity is equal to or larger than the image data capacity (Yes in step S107), the page memory control unit 112 permits the document conveying unit 53 to start conveying the document 50 (step S108). As a result, the document conveying unit 53 starts conveying the document 50.

  Subsequently, the image reading unit 22 optically reads the surface of the document 50 conveyed on the conveyance path 56 by the document conveying unit 53 (step S109). Specifically, the image reading unit 22 converts reflected light from the surface of the document 50 that passes through the reading slit 77 into an electrical signal. That is, the image reading unit 22 optically reads the surface of the document 50 for each line.

  Then, the image data generation unit 111 generates image data of the document 50 read by the image reading unit 22 (step S110). Specifically, the image data generation unit 111 generates image data by performing A / D conversion or the like on the electrical signal converted by the image reading unit 22.

  Then, the page memory control unit 112 sequentially writes the image data generated by the image data generation unit 111 in the page memory 113 (step S111). That is, the page memory control unit 112 sequentially writes the data constituting the image data to the address indicated by the write pointer while sequentially moving the write pointer so as not to overtake the read pointer. That is, the page memory control unit 112 controls writing to the page memory 113 so that new data is not written to an address where unread data is stored.

  Next, the page memory control unit 112 reads the image data stored in the page memory 113 in response to the request from the compression encoding unit 114 (step S112). That is, the page memory control unit 112 sequentially reads the data stored at the address indicated by the read pointer while moving the read pointer so as not to overtake the write pointer.

  Subsequently, the compression encoding unit 114 generates a code string by compressing and encoding the image data read out via the page memory control unit 112 (step S113).

  Finally, the image memory control unit 131 writes the code string generated by the compression encoding unit 114 in the image memory (step S114).

  In this manner, the page memory control unit 112 controls the page memory 113 using a logical page having a capacity smaller than the capacity corresponding to the maximum size document 50. Therefore, it is not necessary for the image reading storage device 17 to always secure a capacity of image data corresponding to the maximum size document before reading. That is, the image reading storage device 17 can efficiently use the page memory.

  Further, the page memory control unit 112 prohibits the start of conveyance of the document 50 when there is no empty logical page. Therefore, it is possible to prevent the free space of the page memory from being insufficient during the reading of the document 50 without calculating the free space of the page memory 113.

  6 and 7 are flowcharts showing a flow of processing related to the calculation of the free space of the page memory by the page memory control unit 112. That is, FIGS. 6 and 7 are diagrams showing details of the process in step S105 of FIG.

  First, the page memory control unit 112 determines whether there is a logical page in a write state (step S201). If there is a logical page in the write state (Yes in step S201), the page memory control unit 112 acquires the start address of the logical page in the write state as the write start address (step S202). On the other hand, when there is no logical page in the write state (No in Step S201), the page memory control unit 112 acquires the page memory head address as the write start address (Step S203).

  Next, the page memory control unit 112 determines whether data is being written to the page memory 113 (step S204). Here, when data is being written to the page memory 113 (Yes in step S204), the page memory control unit 112 acquires the address currently being written as a write pointer (step S205). On the other hand, when data is not being written to the page memory 113 (No in step S204), the page memory control unit 112 acquires the write start address as a write pointer (step S206). Here, the writing start point address indicates an address managed by the page memory control unit 112 as a position where image data is to be written next.

  Then, the page memory control unit 112 determines whether or not to start reading out the image data without waiting for the writing of the image data to end (step S207). For example, when the multifunction device 1 accepts an image rotation instruction from the user via the operation panel 15, the page memory control unit 112 waits for completion of writing of each image data and starts reading the image data. To do. This is because the image reading / storing device 17 realizes image rotation by controlling the address at which reading from the page memory 113 is started and the reading direction. Specifically, for example, when the image is rotated by 180 degrees, the page memory control unit 112 moves the read pointer in the direction opposite to the direction in which the write pointer has moved from the address where the writing of the image data is completed. Realize 180 degree rotation of the image.

  Here, when reading of the image data is started without waiting for the writing of each image data to be completed (Yes in Step S207), the process proceeds to Step S301 in FIG.

  On the other hand, when the reading of the image data is started after the writing of each image data is finished (No in step S207), the page memory control unit 112 detects the size of the document 50 detected by the sensor unit 45. Is used to calculate the address at which the writing of the image data is to be completed (hereinafter referred to as “predicted address”) (step S208). Specifically, the page memory control unit 112 uses the length sensor 46 to calculate the number of pixels calculated using the width of the document 50 detected by the width sensor 47, as shown in Expression (1) of FIG. A predicted address is calculated using the number of lines calculated using the detected length of the document 50. Then, the page memory control unit 112 changes the address indicated by the write pointer acquired in step S205 or step S206 to the calculated predicted address (step S209).

  Subsequently, the page memory control unit 112 determines whether data is being read from the page memory 113 (step S301). Here, when data is being read from the page memory 113 (Yes in step S301), the page memory control unit 112 acquires an address currently being read as a read pointer (step S302). On the other hand, when data is not being read from the page memory 113 (No in step S301), the page memory control unit 112 acquires a read start address as a read pointer (step S303). Here, the read start address indicates an address managed by the page memory control unit 112 as a position where data is scheduled to be read next.

  Next, the page memory control unit 112 determines whether or not to start reading the image data without waiting for the completion of the writing of the image data (step S304), similarly to the process of step S207. Here, when the reading of the image data is started without waiting for the completion of the writing of the image data (Yes in step S304), the process proceeds to step S306.

  On the other hand, when reading of the image data is started after completion of the writing of the image data (No in step S304), the address indicated by the read pointer acquired in step S302 or step S303 is changed to the read start address. (Step S305). Here, the read start address is an address indicating a position where reading of image data is started. For example, when the image is rotated by 180 degrees, the read start address matches the predicted address calculated in step S208.

  Then, the page memory control unit 112 determines whether or not the write pointer is greater than or equal to the read pointer (step S306). That is, the page memory control unit 112 determines whether or not the address indicated by the write pointer is ahead of the address indicated by the read pointer.

  If the write pointer is greater than or equal to the read pointer (Yes in step S306), the page memory control unit 112 calculates an available area using equation (2) shown in FIG. 7 (step S307). That is, the page memory control unit 112 calculates, as a usable area, an area obtained by adding up the area from the page memory start address to the address indicated by the read pointer and the area from the address indicated by the write pointer to the page memory end address. . The usable area indicates a storage area in which new data can be written because unread data is not stored.

  On the other hand, when the write pointer is smaller than the read pointer (No in step S306), the page memory control unit 112 calculates an available area using equation (3) shown in FIG. 7 (step S308). That is, the page memory control unit 112 calculates an area from the address indicated by the write pointer to the address indicated by the read pointer as an available area.

  Finally, the page memory control unit 112 calculates a free space from the calculated usable area (step S309), and proceeds to the process of step S105 in FIG. Note that the page memory control unit 112 calculates, for example, the product of the usable area and the storage capacity per address as a free capacity.

  As described above, the page memory control unit 112 can calculate the free capacity of the page memory 113 depending on whether or not to start reading the image data after the writing of the image data is completed. Therefore, even when the image reading storage device 17 waits for the completion of the writing of the image data to start reading the image data, the free space of the page memory 113 is insufficient during the reading of the document 50. Can be prevented.

  The image reading and storage device according to the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, what made the various deformation | transformation which those skilled in the art conceivable to this Embodiment is also contained in the scope of the present invention.

  For example, in the above embodiment, the case of reading the front surface of the document 50 has been described. However, the present invention can also be applied to the case of reading the back surface of the document 50.

  In the above embodiment, the page memory control unit 112 does not perform error avoidance processing when an unwritable address is acquired when calculating the free space. However, the page memory control unit 112 may appropriately perform error avoidance processing. Good. For example, the page memory control unit 112 may determine whether the address acquired in step S202 or step S203 is a writable area. If the area is not writable, the page memory control unit 112 may change the acquired address to the page memory start address.

  Further, some of the components constituting the image reading storage device 17 may be configured by one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on one chip. Specifically, a microprocessor, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. It is a computer system comprised including. For example, the image data generation unit 111, the page memory control unit 112, and the compression encoding unit 114 illustrated in FIG. 3 may be configured by one system LSI.

  In addition, the present invention can be realized not only as such an image reading and storing apparatus, but also as an image reading and storing method in which operations of characteristic components included in such an image reading and storing apparatus are used as steps. Can do. Further, the steps included in such an image reading and storing method can be realized as a program for causing a computer to execute the steps. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

  The image reading and storing apparatus according to the present invention can be applied to a scanner apparatus, a copier, a facsimile apparatus, and a multifunction machine.

DESCRIPTION OF SYMBOLS 1 Multifunction machine 13 Modem 15 Operation panel 16 Display 17 Image reading storage device 18 Printer 21 ADF part 22 Image reading part 45 Sensor part 46 Length sensor 47 Width sensor 50 Original 52 Original supply tray 53 Original conveying part 54, 58, 60 Conveyance Roller 56 Transport path 64 Document discharge tray 76 Contact glass 77 Reading slit 79 Scanning unit 80 Light source 81 First mirror 83 Second mirror 85 Third mirror 87 Optical lens 89 Photoelectric conversion element 111 Image data generation unit 112 Page Memory control unit Page 113 Memory 114 Compression encoding unit 131 Image memory control unit 132 Image memory 133 Image processing unit 140 Storage area 141 First logical page 142 Second logical page 143 Third logical page 144 Fourth logical page 145 Write pointer 46 the read pointer

Claims (3)

A document conveying section that sequentially conveys a plurality of documents placed on the placing table one by one;
An image reading unit that optically reads each document conveyed by the document conveying unit;
An image data generation unit that generates image data of each document read by the image reading unit;
A page memory for temporarily storing the image data;
A page memory controller that controls the page memory as a ring buffer and sequentially writes the image data generated by the image data generator to the page memory;
A compression encoding unit that reads out the image data stored in the page memory via the page memory control unit, and generates a code string by compressing and encoding the read image data;
An image memory for storing a code string generated by the compression encoding unit,
The page memory control unit determines whether or not each of the plurality of logical pages obtained by logically dividing the storage area of the page memory is an empty state in which data that has not yet been read is stored. And if there is no empty logical page, prohibit the start of transport of the document,
The image reading and storing device, wherein the plurality of logical pages include a logical page having a storage capacity smaller than a maximum capacity of image data that can be generated by the image data generation unit. In addition, a sensor unit for detecting the size of the document placed on the table is provided,
The page memory control unit further includes:
When there is an empty logical page, a write pointer indicating a position where image data being written is next written and a read pointer indicating a position where image data being read is next read are acquired, and the acquired write pointer Using the read pointer, calculate the free space of the page memory,
When the calculated available capacity is equal to or larger than the image data capacity corresponding to the size of the document detected by the sensor unit, the start of conveyance of the document is permitted,
The image reading and storing device according to claim 1, wherein when the calculated free space is smaller than the amount of image data corresponding to the size of the document detected by the sensor unit, the start of conveyance of the document is prohibited. The page memory control unit
Determine whether to start reading the image data after waiting for the writing of the image data to finish,
When the reading of the image data is started after the writing of the image data is completed, the address at which the writing of the image data is scheduled to be completed is estimated using the size of the document detected by the sensor unit. And
The image reading storage device according to claim 2, wherein the address indicated by the acquired write pointer is changed to an estimated address.

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