JP4796485B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus such as a scanner, and an image forming apparatus such as a copying machine or a multifunction peripheral including the image reading apparatus.

  2. Description of the Related Art In recent years, image forming apparatuses such as copiers and multifunction peripherals that store a plurality of sizes of sheets and automatically select sheets according to the document size and perform copying and the like have become widespread. In such an image forming apparatus, first, it is necessary to detect the document size.

  FIG. 4 is a configuration diagram of an image reading mechanism of a general image reading apparatus 400, and FIG. 6 is a functional block diagram of the image reading apparatus 400.

  The image reading apparatus 400 includes an original table 103 on which an original 409 is placed and an original cover 402 having a white original cover surface 402a. Further, a light source 104 that emits light to the original 409 while moving in the sub-scanning direction indicated by the arrow A, and a CCD (Charge Coupled Device) that receives the light reflected from the original 409 via the mirrors 105, 106, and 107 and converts them into electrical signals. An image sensor 108 such as is provided. Further, a switch 404 that outputs an on / off signal at a predetermined angle when the document cover 402 is opened and closed, and a sensor 405 that is turned on when the document cover 402 is closed are attached.

  In this state, when the user closes the document cover 402 by the predetermined angle so that the document cover 402 is half open, the switch 404 is turned on. Then, the open / close detection unit 601 instructs the reading unit 302 to read the document 409, and based on this, the light source 104 starts sub-scanning.

  FIG. 5 (a) is a schematic diagram of image data obtained by this sub-scanning. A hatched area outside the document 409 is a black area because the document cover 402 is in a half-open state, and no light is reflected on the document cover surface 402a. Here, the white area detection means 603 notified of the detection of the half-open state from the open / close detection means 601 detects the maximum width of the white area in FIG. 5 (a). Specifically, this maximum width is detected by subtracting the minimum value from the maximum value in the sub-scanning direction A and the main scanning direction (direction orthogonal to the sub-scanning direction A) of the coordinates of the pixel where white is detected. Is done.

  Subsequently, when the user completely closes the document cover 402 and the document cover 402 is closed, the sensor 405 is turned on. Then, the open / close detection unit 601 instructs the reading unit 30 to read the document 409, and based on this, the light source 104 starts sub scanning again.

  FIG. 5B is a schematic diagram of image data obtained by this sub-scanning. Since the document cover 402 is closed in the area outside the document 409, the light is reflected from the document cover surface 402a to become a white area, and for example, a character area or the like in the document 409 is a black area. Here, the black area detecting means 604 notified of the detection of the closed state from the open / close detecting means 301 detects the maximum width of the black area in FIG. 5 (b). The method for detecting the maximum width is the same as described above.

  When two maximum widths are detected for each of the white area and the black area as described above, the size detection unit 605 compares the two maximum widths, and the size of the original 409 is determined based on the larger numerical value. Is identified. As described above, the detection of the size of the document 409 based on the two regions of the white region and the black region is performed twice in the half-open state and the closed state of the document cover 402. This is for prevention.

That is, when the document table 103 and the document cover surface 402a are dirty or dust is attached, a black region may appear outside the document 409 in FIG. 5B. In such a case, if the document size is detected based only on the black area, a document size larger than necessary will be detected. If only a small part of the original 409 is printed, if the original size is detected based only on the black area, a small original size corresponding to only this part is detected. It is difficult to faithfully copy and the like.
For this reason, as described above, image reading apparatuses that detect the document size based on the two areas of the white area and the black area have come into wide use. For example, Patent Documents 1 and 2 below And the like.
Japanese Patent Laid-Open No. 11-122582 JP-A-8-204912

  However, the above prior art has the following problems.

  That is, in the above-described prior art, first, the white area detecting unit 603 detects the white area when the document cover 402 is in the half-open state, and then the black area detecting unit 604 detects the black area when the document cover 402 is closed. Yes. For this reason, two types of circuits (detecting means 603 and 604) for detecting the white region and the black region have to be created, which complicates the circuit configuration and increases the cost.

  The present invention has been made in view of such problems, and by detecting a white area and a black area with a single circuit, while ensuring accurate document size detection, it is inexpensive with a simple circuit configuration. An object of the present invention is to provide an image reading apparatus that can be produced.

  In order to achieve the above object, the present invention employs the following means.

  An image reading apparatus according to the present invention includes a document table on which a document is placed, a document cover that opens and closes to the document table, and an open / close detection unit that detects a half-open state and a closed state of the document cover.

Further, the image reading apparatus of the present invention includes a logic inversion circuit that inverts the density of image data read by the reading means in each of the half-open state detection and the closed state detection, and the half-open state. An area having a predetermined density or less is detected in the image data read by the reading unit when the state is detected, and is read by the reading unit and inverted by the logic inversion circuit when the closed state is detected. Based on a comparison between the area detected when detecting the half-open state by the area detecting means and the area detected when detecting the closed state by the area detecting means Selecting means for specifying the size of the original .

  Here, the area having a predetermined density or less corresponds to, for example, a black area in the background art. The area detecting means detects an area having a predetermined density or less in the black area, that is, an area having a black density equal to or less than the predetermined density.

  Next, the density of the image data used for detection of the black area is inverted by a logic inversion circuit. As a result, the portion where the black density was high before inversion is high in white density, and image data in which the density is inverted is acquired. As described above, the area detecting means detects an area having a predetermined density or less with respect to the inverted image data. Here, the area that is equal to or lower than the predetermined density for the image data corresponds to, for example, the white area in the background art. The area detecting means detects an area having a predetermined density or less in the white area, that is, an area having a white density equal to or less than the predetermined density.

  As described above, the white area is also detected by the area detecting means used for detecting the black area by inverting the density of the image data by the logic inversion circuit. Thereby, the white area and the black area can be detected by one circuit.

An image forming apparatus that performs copying or the like using the configuration of the present invention can also be provided. That is, a reading unit that generates image data by reading an original manuscript, a paper cassette that stores sheets of a plurality of sizes, detected upon detection of the detected area and the closed state when the detection of the half-open state by said area detection means Based on the comparison with the region, a selection unit for selecting a specific size paper from the paper and a printing unit for printing the image data on the specific size paper are provided. Accordingly, it is possible to provide an image forming apparatus such as a copying machine or a multi-function machine that automatically selects a sheet according to the document size and performs copying. The present invention also provides an image reading method. The image reading method includes a half-open detection step for detecting a half-open state of a document cover that opens and closes with respect to a document table, a half-open reading step for reading image data of a document placed on the document table in the half-open state, and a document table A closing detection step for detecting a closed state of the document cover that opens and closes. Further, the image reading method includes a closed reading step for reading image data of a document placed on a document table in the closed state, an inversion step for inverting the density of image data read in the closed reading step, A half-open state region detecting step for detecting a region having a predetermined density or less with respect to the image data read in the half-open reading step. Further, the image reading method is detected when the half-open state is detected by the closed state region detecting step for detecting a region having a predetermined density or less in the image data inverted in the inversion step, and the half-open state region detecting step. And a selection step for specifying the size of the document based on a comparison between the region detected by the closed state detection step and the region detected when the closed state is detected.

  As described above, according to the present invention, it is possible to detect the white area and the black area with one circuit by using the logic inversion circuit. Therefore, it is possible to provide an image reading apparatus that can be produced at a low cost with a simple circuit configuration while ensuring accurate document size detection as in the prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In this embodiment, the present invention is embodied as a digital multi-function peripheral including an image reading device.

  FIG. 1 is a conceptual diagram showing the overall configuration of the multifunction peripheral 100 according to the present embodiment. When a user reads a document using a multifunction machine, the document is placed on, for example, the document table 103 and a reading instruction is given to the operation buttons on the touch panel 140 provided near the document table 103. When such an instruction is given, reading is performed by the operation of each unit (drive unit) described below.

  In the image reading unit 101, the light emitted from the light source 104 is reflected by the document placed on the document table 103, and is guided to an image sensor 108 such as a CCD (Charge Coupled Device) by mirrors 105, 106, and 107. The image sensor 108 photoelectrically converts the received light to generate document image data. At this time, an original size of the read image data is detected by a detection mechanism which will be described later, and based on this, an optimal size paper is selected from the paper feed cassette 114, and printing is performed as follows.

  The photosensitive drum 109 provided in the image forming unit 102 rotates in a predetermined direction at a constant speed, and around the charger 110, the exposure unit 111, the developing unit 112, and the transfer around the periphery in order from the upstream side in the rotation direction. A device 113 and the like are arranged. The charger 110 uniformly charges the surface of the photosensitive drum 109. The exposure device 111 irradiates light according to the image data read by the image reading unit 101, and forms an electrostatic latent image on the photosensitive drum 109. The developing unit 112 attaches toner to the electrostatic latent image formed by the exposure unit 111 and forms a toner image on the photosensitive drum 109. The transfer unit 113 transfers the toner image on the photosensitive drum 109 onto a sheet. In this way, the series of processes is performed in the image forming unit 102 as the photosensitive drum 109 rotates.

  Further, when performing printing, the image forming unit 102 draws one sheet from any one of the sheet feeding cassettes 114 to the conveyance path using the pickup roller 115. Each sheet cassette 114 stores sheets of different sizes, and the sheets of the optimum size are fed. The sheet pulled out to the conveyance path is sent between the photosensitive drum 109 and the transfer unit 113 by the conveyance roller 116 and the registration roller 117.

  When the sheet passes between the heating roller 119 and the pressure roller 120 in the fixing device 118, the visible image is fixed on the sheet by heat and the pressing force on the sheet. In order to perform the fixing appropriately, the heat amount of the heating roller is optimally set according to the paper size. The image forming unit 102 discharges the paper that has passed through the fixing device 118 to the paper discharge tray 121.

  FIG. 2 is a schematic configuration diagram related to control of the multifunction peripheral 100 according to the present embodiment.

  The multifunction device 100 includes a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read On 7 Memory) 203, an HDD (Hard Disk Drive) 204, and a driver 205 corresponding to each driving unit in the above printing. They are connected via a bus 206. The CPU 201 uses, for example, the RAM 202 as a work area, executes a program stored in the ROM 203, the HDD 204, etc., and transmits and receives data and commands to and from the driver 205 based on the execution result, as shown in FIG. The operation of each driving unit is controlled. Further, each means (shown in FIG. 3) to be described later other than the above-described drive unit operates as each means when the CPU 201 executes the program.

  FIG. 3 is a functional block diagram of the multifunction peripheral 100 according to the present embodiment. Further, the multifunction peripheral 100 of the present invention includes an image reading apparatus 400 as shown in FIG. 4 as in the above background art. A document size detection mechanism in the multifunction peripheral 100 of the present invention will be described with reference to these drawings. Note that each component of the image reading apparatus 400 (such as the document cover 402) is the same as that in the background art described above, and thus the description thereof is omitted.

  When the user closes the document cover 402 by a predetermined angle and the document cover 402 is half open, the switch 404 is turned on. Then, the open / close detection unit 301 instructs the reading unit 302 to read the document 409, and based on this, the light source 104 starts sub-scanning.

  FIG. 5 (a) is a schematic diagram of image data obtained by this sub-scanning. A hatched area outside the document 409 is a black area without reflecting light from the document cover surface 402a because the document cover 402 is in a half-open state. Here, the open / close detection unit 301 inputs the image data as it is to the region detection unit 304 by the selector 307. Then, this area detecting means 304 detects the maximum width of the area below the predetermined density in FIG. 5 (a). Here, the area of a predetermined density or less corresponds to the white area in the background art, but in the present invention, it can be adapted to color original paper.

  Here, the maximum width is specifically the minimum value from the maximum value in the sub-scanning direction A and the main scanning direction (direction perpendicular to the sub-scanning direction A) of the coordinates of the (white) pixels having a predetermined density or less. Detected by decreasing the value. This is the same as the background art described above.

  Subsequently, when the user completely closes the document cover 402 and the document cover 402 is closed, the sensor 405 is turned on. Then, the open / close detection unit 301 instructs the reading unit 302 to read the document 409, and based on this, the light source 104 starts another sub-scanning.

  FIG. 5B is a schematic diagram of image data obtained by this sub-scanning. Since the document cover 402 is closed in the area outside the document 409, the light is reflected from the document cover surface 402a to become a white area, and for example, a character area or the like in the document 409 is a black area.

  Here, the open / close detection unit 301 selects the logic inversion circuit 303 by the selector 307. The logic inversion circuit 303 inverts the density of the image data read by the reading unit 302 when the half-open state of the document cover 402 is detected and when the document cover 402 is detected. The logic inversion circuit 303 of this embodiment inverts the density of the image data obtained by the second sub-scanning, that is, the image data read at the time of detecting the closed state, and inputs the result to the region detecting unit 304. That is, as shown in FIG. 5C, the image data in FIG. 5 (b) is reversed in shade (black and white), and the character area in the document 409 becomes a white area and is input to the area detection unit 304. It is done.

  In the present embodiment, the density of the image data read when the closed state is detected is inverted, but the density of the image data read when the half-open state is detected may be inverted.

  The area detection unit 304 detects the maximum width of an area (white area) having a predetermined density or less with respect to the inverted image data, as described above. However, this is exactly the same as detecting the maximum width of the black region (region having a predetermined density or more) in the background art. In other words, the provision of the logic inversion circuit 303 makes it possible for the present invention to detect two regions, a white region and a black region, by one region detecting means 304 (one circuit). .

  As described above, when two maximum widths are detected, that is, the maximum width obtained in the first sub-scanning, the maximum width obtained in the second sub-scanning, and the maximum width obtained in the second sub-scanning, the selection unit 305 The size of the original 409 is specified based on the larger numerical value, and the paper used for printing is selected from the paper feed cassette 114. The printing unit 306 acquires image data from the reading unit 302 and prints the image data on the selected paper.

  As described above, in the MFP 100 according to the present invention, the white area and the black area are detected in the same manner as in the background technique using the only area detecting means 304, and the accurate document size is detected in the same manner as in the background technique. Is secured.

  The image reading apparatus according to the present invention can detect a white area and a black area with one circuit by using a logic inversion circuit. For this reason, it can be produced inexpensively with a simple circuit configuration while ensuring accurate document size detection as in the prior art. Therefore, it is useful as an image reading apparatus such as a scanner, and a copying machine or a multi-function machine equipped with the image reading apparatus.

1 is a conceptual diagram illustrating an overall configuration of a multifunction machine as an embodiment of the present invention. 1 is a schematic configuration diagram related to control of a multifunction peripheral as an embodiment of the present invention. FIG. 1 is a block diagram of a multifunction machine as an embodiment of the present invention. 1 is a configuration diagram of an image reading mechanism of a multifunction machine as an embodiment of the present invention. FIG. Explanatory drawing of the detection of a white area | region and a black area | region. FIG. 10 is a block diagram of a conventional image reading apparatus.

Explanation of symbols

100 MFP
101 Image reader
102 Image forming unit
103 Document table
301 Open / close detection means
302 Reading means
303 logic inversion circuit
304 Area detection means
305 selection means
306 Printing means
307 selector
400 image reader
402 Document cover
402a Original cover
404 switch
405 sensor
409 Manuscript

Claims (3)

An original table on which an original is placed;
Reading means for reading image data of a document placed on the document table;
A document cover that opens and closes with respect to the document table;
Open / close detecting means for detecting a half-open state and a closed state of the document cover;
A logic inversion circuit for inverting the density of the image data read by the reading means in each of the half-open state detection and the closed state detection;
A region having a predetermined density or less is detected in the image data read by the reading unit when the half-open state is detected, and is read by the reading unit and inverted by the logic inversion circuit when the closed state is detected. Area detecting means for detecting an area having a predetermined density or less with respect to the obtained image data;
An image reading apparatus comprising: a selecting unit that specifies a size of the document based on a comparison between an area detected when the half-open state is detected by the area detecting unit and an area detected when the closed state is detected . A paper cassette for storing multiple sizes of paper,
An original table on which an original is placed;
Reading means for reading image data of a document placed on the document table;
A document cover that opens and closes with respect to the document table;
Open / close detecting means for detecting a half-open state and a closed state of the document cover;
A logic inversion circuit for inverting the density of the image data read by the reading means in each of the half-open state detection and the closed state detection;
A region having a predetermined density or less is detected in the image data read by the reading unit when the half-open state is detected, and is read by the reading unit and inverted by the logic inversion circuit when the closed state is detected. Area detecting means for detecting an area having a predetermined density or less with respect to the obtained image data;
Selection means for selecting a sheet of a specific size from the sheets based on a comparison between the area detected when the half-open state is detected by the area detection unit and the area detected when the closed state is detected;
Printing means for printing the image data on the specific size paper;
An image forming apparatus comprising: A half-open detection step for detecting a half-open state of the document cover that opens and closes with respect to the document table;
A half-open reading step for reading image data of a document placed on the document table in the half-open state;
And closing detecting step of detecting a closed state of the document cover to be opened and closed with respect to the document table,
A closed reading step for reading image data of a document placed on the document table in the closed state;
An inversion step of inverting the shade of the image data read in the closed reading step;
A half-open state region detecting step for detecting a region having a predetermined density or less with respect to the image data read in the half-open reading step;
A closed state detection step for detecting a region having a predetermined density or less with respect to the image data inverted in the inversion step;
The size of the original is specified based on a comparison between the area detected when the half-open state is detected by the half-open area detection step and the area detected when the closed state is detected by the closed-state area detection step. An image reading method comprising a selection step .

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