JP2013098967A - Original size detection apparatus and original size detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original size detection apparatus capable of detecting the size of an original quickly.SOLUTION: The original size detection apparatus comprises: a light source which irradiates an original placed on an original table with light and scans in a first direction parallel to the surface of the original table; a read controller which issues an instruction to read image data in a determination range as a preset partial range of one line along a second direction perpendicular to the first direction, the range being irradiated with the light from the light source; a reading unit for reading image data in the determination range indicated by the read controller, on the basis of the light incident to the determination range; and a size detector 153 which detects the size of the original on the basis of the image data in the determination range.

Description

  The present invention relates to a document size detection device and a document size detection method.

  Conventionally, image reading apparatuses such as image scanners, image forming apparatuses such as copiers, facsimiles, and printing apparatuses equipped with an original reading apparatus automatically adjust the size of an original placed on a transparent original plate such as contact glass. It has the function to discriminate by.

  As a method for detecting the document size, a method is generally known in which a reflective sensor is installed at a position corresponding to various standard document sizes such as B4, A4, and B5, and the document size is determined from a combination of the responses. Yes.

  However, in recent years, as a part of cost reduction, a method of detecting a document size using a line sensor for reading a document instead of using a reflective sensor has also been adopted (see, for example, Patent Document 1).

  In a document size detection method using a line sensor, an image signal of a document read by a CCD (Charge Coupled Device Image Sensor) is first converted into a digital signal in an image reading apparatus, and image data corresponding to the document is obtained. Then, in the image reading apparatus, the obtained image data is stored in the line memory, the image data stored in the line memory is referred to by memory access by the CPU, and the document size is determined based on the image data. Do.

  As shown in FIG. 11A, in the CCD, charges move from the photodiode array 400 to the analog shift registers 401a and 401b at the timing when the shift signal is asserted. That is, the assertion interval of the shift signal corresponds to the exposure time per line. After the exposure time elapses, the charges of the plurality of analog shift registers 401a and 401b provided corresponding to the respective photodiodes are transferred to the output buffers 402a and 402b, subjected to charge-voltage conversion, and then output to the outside. The

  In principle, the CCD always reads out all pixels. For this reason, as shown in FIG. 11B, it is necessary to input a number of transfer clocks equal to or greater than the total number of pixels of the photodiode array 400 during the assertion interval of the shift signal. That is, for example, when the photodiode array 400 has 7300 photodiodes, the charge of the last effective pixel is output after 7300 clocks have elapsed.

  In order to detect the document size, it is only necessary to obtain only a predetermined range of image data corresponding to the document size to be detected from the lines detected by the line sensor. However, as described above, in the CCD of the conventional image reading apparatus, it is necessary to read out all pixels of the line. For this reason, there has been a problem that necessary image data cannot be obtained unless the number of transfer clocks equal to or greater than the total number of pixels of the photodiode array has elapsed, and the document size detection process takes time.

  The present invention has been made in view of the above, and an object of the present invention is to provide a document size detection device and a document size detection method capable of quickly detecting a document size.

  In order to solve the above-described problems and achieve the object, the present invention provides a document size detection device for detecting the size of a document placed on a document table, wherein the document placed on the document table is illuminated with light. And a light source that scans in a first direction parallel to the surface of the document table, and one line in a second direction perpendicular to the first direction that is irradiated with light from the light source is set in advance. A reading control unit that instructs reading of image data in a determination range that is a partial range, and reading that reads the image data in the determination range instructed by the reading control unit based on light incident on the determination range And a size detection unit that detects the size of the document based on the image data in the determination range.

  According to another aspect of the present invention, there is provided a document size detection method executed by a document size detection device for detecting a size of a document placed on a document table, wherein the document size is detected by scanning in a first direction parallel to the surface of the document table. , An irradiation step of irradiating light on the document placed on the document table, and a predetermined partial range of one line in the second direction perpendicular to the first direction where the light is irradiated. A reading control step for instructing reading of image data in a determination range; a reading step for reading the image data in the determination range instructed in the reading control step based on light incident on the determination range; and the determination range And a size detecting step of detecting the size of the document based on the image data.

  According to the present invention, it is possible to quickly detect the document size.

FIG. 1 is a diagram illustrating a main configuration of the scanner unit. FIG. 2 is a block diagram showing the configuration of the CMOS sensor and the signal processing unit. FIG. 3 is a diagram illustrating a data configuration of the document size determination table. FIG. 4 is a diagram showing the determination range of each document size. FIG. 5 is a diagram illustrating a data configuration of the determination result writing table. FIG. 6 is a diagram illustrating a data configuration of the document size determination table. FIG. 7A is a diagram for explaining the timing of starting the document size detection process. FIG. 7B is a diagram for explaining the timing of starting the document size detection process. FIG. 8A is a diagram for explaining the carriage position. FIG. 8-2 is a diagram for explaining the carriage position. FIG. 9 is a flowchart illustrating document size detection processing according to the image forming apparatus 1. FIG. 10 is a diagram illustrating an example of writing to the determination result writing table. FIG. 11A is a diagram illustrating a main configuration of a CCD photodiode array. FIG. 11B is a diagram for explaining the transfer clock.

  Hereinafter, embodiments of a document size detection device and a document size detection method will be described in detail with reference to the accompanying drawings.

  In the present embodiment, an image forming apparatus as an example of a document size detection apparatus will be described. The image forming apparatus according to the present embodiment includes a scanner unit for document reading processing, and detects a document size based on image data read by the scanner unit. The image forming apparatus according to the present embodiment also realizes a copy function by forming an image based on the image data obtained by the scanner unit.

  FIG. 1 is a diagram illustrating a main configuration of a scanner unit of the image forming apparatus 1 according to the first embodiment. The scanner unit obtains image data by reading a document image with a CMOS (Complementary Metal Oxide Semiconductor) line sensor (hereinafter referred to as a CMOS sensor) and converting it into a digital signal.

  The image forming apparatus 1 includes a contact glass 100 as a document table on which a document 200 to be read is placed, a white reference plate 102, a light source 111, reflection mirrors 112 to 114, a first carriage 115, and a second carriage. A carriage 116, a lens unit 117, a sensor board 118, a signal cable 119, a CMOS sensor 120, and a signal processing unit 130 are provided. The first carriage 115 is equipped with a light source 111 and a first reflecting mirror 112. The second carriage 116 is equipped with a second reflecting mirror 113 and a third reflecting mirror 114.

  The light emitted from the light source 111 is reflected by the original placed on the contact glass 100, enters the lens unit 117 through the reflection mirrors 112 to 114, is collected by the lens unit 117, and is mounted on the sensor board 118. An image is formed on the formed CMOS sensor 120. A signal output from the CMOS sensor 120 is input to the signal processing unit 130 via the signal cable 119. The white reference plate 102 is used to correct various distortions caused by an optical system for reading a document. The first carriage 115 and the second carriage 116 are controlled in a predetermined direction (in the direction of arrow A in the figure) parallel to the main surface of the contact glass 100 by controlling a stepping motor (not shown) during the scanning operation (scanning). Moving. Here, the direction in which the first carriage 115 and the second carriage 116 move is referred to as a sub-scanning direction. The light source 111 and the reflection mirrors 112 to 114 are formed in a shape extending in the main scanning direction. Here, the main scanning direction is a direction parallel to the main surface of the contact glass 100 and perpendicular to the sub-scanning direction.

  FIG. 2 is a block diagram showing the configuration of the CMOS sensor 120 and the signal processing unit 130 described in FIG. The CMOS sensor 120 includes a photodiode array 121, a switch 122, a charge / voltage converter 123, an amplifier circuit 124, and an output buffer 125. The photodiode array 121 has a plurality of photodiodes along the main scanning direction. A range in the main scanning direction corresponding to the plurality of photodiode arrays is referred to as one line.

  A plurality of switches 122, charge-voltage conversion units 123, and amplifier circuits 124 are provided corresponding to the plurality of photodiodes included in the photodiode array 121. In the image forming apparatus 1 according to the present embodiment, 7300 pixels are used as one line, and the photodiode array 121 includes 7300 photodiodes.

  Each photodiode generates a charge corresponding to the amount of light irradiated. The charge generated in the photodiode is converted into a voltage amount in the charge-voltage converter 123. That is, the charge-voltage conversion unit 123 generates a voltage amount corresponding to the photosensitive amount of the corresponding photodiode. Further, the voltage signal output from the charge voltage conversion unit 123 is amplified by the amplification circuit 124 at an amplification factor according to the operation range of the ADC 131 described later. The amplified voltage signal is input to the signal processing unit 130 via the output buffer 125.

  The switch 122 is controlled to be turned on / off by a read control signal output from a read control unit 134 described later. The charge generated in the photodiode array 121 moves to the charge-voltage conversion unit 123 provided corresponding to each photodiode only when the switch 122 is on. In a normal document reading operation, the switch 122 corresponding to the photodiode of the first pixel is turned on in order.

  The signal processing unit 130 includes an ADC 131, an image processing unit 132, a size detection control unit 133, a read control unit 134, a register unit 140, a multiplier 150, a smoothing unit 151, and a binarization calculation unit 152. And a size detection unit 153 and a timing signal generation unit 154.

  The ADC 131 converts the voltage signal input from the CMOS sensor 120 into 10-bit digital image data. The digital image data is output to the image processing unit 132 and the multiplier 150. The image processing unit 132 performs various image processes on the digital image data.

  The size detection control unit 133 starts the size detection process at a predetermined timing. The timing for starting the size detection process will be described later. Specifically, the size detection control unit 133 enables the read control unit 134 to detect a document size by enabling a start register (not shown) provided in a register unit 140 described later at a predetermined timing. Instruct to output a control signal, and further instruct the multiplier 150, the smoothing unit 151, the binarization calculation unit 152, and the size detection unit 153 to start processing.

  Operation settings in the CMOS sensor 120 or the like can be set and stored in the register unit 140 as a storage unit. The register unit 140 stores various information such as operation settings. Here, information stored in the register unit 140 will be described. FIG. 3 is a diagram illustrating a data configuration of the document size determination table 141 stored in the register unit 140.

  The document size determination table 141 is a table that is referred to by the size detection unit 153 described later for detecting the document size. Specifically, the document size determination table 141 stores the document size and the start address of the determination range in association with each other. Here, the determination range is a range of pixels that the CMOS sensor 120 should read out in order to determine the document size.

  FIG. 4 is a diagram showing determination ranges 301 to 305 for each document size. Each of the determination ranges 301 to 305 is a range of a predetermined number of pixels (predetermined pixel length) arranged in the main scanning direction (the direction of arrow B in the figure). Note that the number of pixels included in the determination range is arbitrary. In this embodiment, it is 32 pixels.

  As shown in FIG. 4, when placing a document to be read on the contact glass 100, the document is placed on the contact glass 100 so that one of the vertices of the document coincides with a predetermined vertex 101 of the contact glass 100. I will do it. Hereinafter, placing an original on the contact glass 100 so that the apex 101 of the contact glass 100 coincides with the apex 101 of the contact glass 100 is referred to as setting the original.

  The larger the document size of the document set on the contact glass 100, the longer the range in which the document covers the contact glass 100 in the main scanning direction of the contact glass 100 (the direction of arrow B in the figure). Therefore, when an original is set on the contact glass 100, an area in which an original having a document size to be determined is disposed and an original having a document size smaller than the original to be determined is not disposed. A determination range for the target document size is set in advance.

  For example, the B5 horizontal document size determination range 302 is an area in which a document having a B5 horizontal document size is arranged, but an A5 horizontal document having a smaller document size than the B5 horizontal is not arranged.

  As a result, when white image data is obtained within the predetermined document size determination range, that is, when there is a document, it can be seen that a document of a corresponding document size or larger is set. In addition, when black image data is obtained in the determination range, that is, when there is no document, it can be seen that a document of a corresponding document size or larger is not set. It should be noted that the document size of the document set on the contact glass 100 can be specified by integrating the determination results in the determination ranges of different document sizes.

  As described above, in the present embodiment, the pixel length of the determination range is 32 pixels regardless of the document size. Therefore, it is set in advance in the register unit 140 that the pixel length of the determination range is 32 pixels, and only the start address of the determination range is stored as the determination range in the document size determination table 141 shown in FIG. And Thereby, the determination range can be specified by the pixel length of the determination range of the register unit 140 and the start address stored in the document size determination table 141.

  As another example, the pixel length of the determination range may be different for each document size. As another example, the document size determination table 141 may store the start address and the pixel length of the determination range as the determination range in association with each document size.

  FIG. 5 is a diagram illustrating a data configuration of the determination result writing table 142 stored in the register unit 140. Thus, the determination result writing table 142 has a 1-bit writing area for each document size. The writing area of the determination result writing table 142 is an area in which the determination result of each document size is written by the binarization calculation unit 152. Specifically, “1” is written when it is determined that there is a document, and “0” is written when it is determined that there is no document. The values written in the writing area corresponding to each document size in the determination result writing table 142 are processed as the values of Bit 0 to Bit 4 in order from the smallest document size.

  FIG. 6 is a diagram illustrating a data configuration of the document size determination table 143 stored in the register unit 140. The document size determination table 143 is a table that is referenced by the size detection unit 153 to determine the document size. The document size determination table 143 stores evaluation values and document sizes in association with each other. The evaluation value is a value calculated based on the determination result written in the determination result writing table 142 shown in FIG. The evaluation value will be described in detail later.

  The read control unit 134 refers to the document size determination table 141 stored in the register unit 140 and sends a read control signal to the CMOS sensor 120 that instructs reading of image data in a determination range determined by the start address of A5 horizontal. . The reading control unit 134 reads the determination ranges of the respective document sizes (all document sizes stored in the document size determination table 141) from B5 to A3 / A4 in the same manner as the A5 horizontal document size. Send control signals sequentially.

  The multiplier 150 amplifies the image data by multiplying each of the 32-pixel image data within the determination range read from the CMOS sensor 120 by the control of the read control unit 134 by a predetermined value. Note that the value multiplied by the multiplier 150 is a preset value. It can be arbitrarily set based on the amount of light emitted from the light source 111. The smoothing unit 151 smoothes the input image data. Specifically, the smoothing unit 151 adds the input image data and calculates the average level (A).

  The binarization calculation unit 152 compares the average level (A) with a preset threshold value (X), and binarizes the comparison result. Here, the threshold (X) is a predetermined value between the full gradation (white) and 0 gradation (white) of the image data. The threshold value (X) can be arbitrarily set based on the amount of light emitted from the light source 111.

  The binarization calculation unit 152 writes the binarized value as the determination result in the writing area associated with the document size to be processed in the determination result writing table 142. Specifically, when the average level (A) is equal to or greater than the threshold value (X), it is determined that there is no document, “0” is written, and when the average level (A) is less than the threshold value (X), the document Judge that there is, write “1”.

  The size detection unit 153 obtains an evaluation value based on each value written in the determination result writing table 142 by the binarization calculation unit 152. Specifically, the size detection unit 153 converts the number written in the writing area corresponding to each document size in the determination result writing table 142 to each decimal place of Bits 0 to 4 to a decimal number. The value after conversion is used as the evaluation value.

  The size detection unit 153 further refers to the document size determination table 143 and specifies the document size associated with the obtained evaluation value. That is, the size detection unit 153 detects the document size of the document set on the contact glass 100 as the specified document size.

  The timing signal generation unit 154 generates an internal timing signal referred to by each unit in the image forming apparatus 1 including the ADC 131 based on a reference clock acquired from the outside. The ADC 131 operates according to the internal timing signal.

  The image forming unit 160 selects a recording sheet suitable for the document size based on the document size detected by the size detection unit 153. The image forming unit 160 forms an image on the selected recording sheet based on the image data obtained by the image processing unit 132.

  FIGS. 7A and 7B are diagrams for explaining the timing of starting the document size detection process. The image forming apparatus 1 includes an openable / closable document pressure plate 170 that covers the contact glass 100 and an open / close sensor 171 that detects that the document pressure plate 170 is closed. As shown in FIG. 7A, when setting the document, the user opens the document pressure plate 170 and sets the document 200 to be read on the contact glass 100. Thereafter, the user closes the original platen 170 as shown in FIG. 7B, and inputs a scan start at an operation unit (not shown). When the open / close sensor 171 detects that the document pressure plate 170 is closed in a state where the scan start is input, the size detection control unit 133 starts the size detection process.

  8A and 8B are diagrams for explaining the carriage position when the document size detection process is started. As shown in FIG. 8A, the first carriage 115 is positioned at a predetermined first position below the contact glass 100 during standby when the scanning operation is not performed. When the start of scanning is input from the user and the open / close sensor 171 detects that the document pressure plate 170 is closed, light is emitted from the light source 111 and the size detection process is started. Subsequently, as shown in FIG. 8B, the first carriage 115 and the second carriage 116 move so that the first carriage 115 is positioned below the white reference plate 102, and the first carriage 115 is moved to the white reference plate. Positioned at a predetermined second position below 102, scanning of the document is then started.

  FIG. 9 is a flowchart illustrating document size detection processing according to the image forming apparatus 1. When the user sets a document, the document pressure plate 170 is closed, and a size detection start signal is input from the open / close sensor 171 to the size detection control unit 133 (step S100, Yes), the size detection control unit 133 performs size detection processing. To start. Specifically, the reading control unit 134 is instructed to start processing, and each unit such as the multiplier 150 that performs document size detection processing is instructed to start processing.

  Next, the reading control unit 134 refers to the document size determination table 141 stored in the register unit 140, and specifies the start address of A5 horizontal (step S102). The read control unit 134 further sends a read control signal instructing reading of pixels within the determination range for the read pixels from the start address to the CMOS sensor 120 (step S104).

  Next, in the CMOS sensor 120, pixels in the determination range are read (step S106). That is, according to the read control signal, the switch 122 in the determination range is turned on, and the charge generated in the photodiode in the determination range is converted into a voltage amount in the charge-voltage converter 123 and further amplified in the amplifier circuit 124, and then signal processing is performed. Sent to the unit 130.

  In the signal processing unit 130, after the voltage signal is converted into image data in the ADC 131, the multiplier 150 multiplies the image data of 32 pixels in the determination range, thereby amplifying the image data (step S108).

  Next, the smoothing unit 151 smoothes the image data by adding the amplified image data and calculating the average level (A) (step S110). Next, the binarization calculation unit 152 binarizes the average level (A) by comparing the average level (A) with the threshold value (X) (step S112). Specifically, a value of 0 is generated when the average level (A) is equal to or greater than the threshold (X), and a value of 1 is generated when the average level (A) is smaller than the threshold (X). Next, the binarization calculation unit 152 writes the generated value in the writing area associated with the target document size in the determination result writing table 141 (step S114).

  The processing from step S102 to step S114 is repeated for each document size stored in the document size determination table 141 (step S116, No), and all document sizes stored in the document size determination table 141 are stored. When the above processing is completed (step S116, Yes), the size detection unit 153 detects the document size based on the value written in the determination result writing table 142 by the binarization calculation unit 152 (step S118). . This completes the document detection process.

  Here, the size detection process (step S118) from the data write process (step S114) will be described in detail with reference to FIG. In the data writing process (step S114), the binarization calculation unit 152 first generates data generated for the determination range corresponding to the A5 horizontal document size by using the A5 horizontal document size (Bit0) of the determination result writing table 142. ) Is written in the writing area corresponding to. Similarly, the binarization calculation unit 152 writes the value of the determination result generated for the determination range corresponding to each document size in Bit1 to Bit4.

  In the size detection process (step S118), the size detection unit 153 refers to the determination result writing table 142, and sets the number written in the writing area corresponding to Bits 0 to 4 to 10 in each binary number. Convert to a decimal number and get the evaluation value. For example, it is assumed that 1, 1, 1, 0, 0 are written in Bits 0 to 4, respectively, as shown in FIG. In this case, the size detection unit 153 obtains the evaluation value 7. Then, the size detection unit 153 refers to the document size determination table 143 and detects the document size associated with the evaluation value as the document size of the document set on the contact glass 100. When the evaluation value 7 is obtained, the size detection unit 153 specifies the document size A4 horizontal / A5 length associated with the evaluation value 7 in the document size determination table 143, and detects this as the document size. To do.

  As described above, in the image forming apparatus 1 according to the present embodiment, the document size of the document set on the contact glass 100 can be detected by only reading the pixels in the determination range. Therefore, it is not necessary to read out all the pixels for one line in the main scanning direction like the CCD line sensor in order to detect the document size, and the processing time for the document size detection process can be shortened.

  In the above embodiment, the image forming apparatus has been described as an example of the document size detection device. However, the document size detection device is a multifunction device having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function. The present invention can be applied to any image forming apparatus such as a copying machine, a printer, a scanner apparatus, and a facsimile apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 120 CMOS sensor 121 Photodiode array 122 Switch 123 Charge voltage converter 124 Amplifier circuit 133 Size detection control part 134 Read control part 140 Register part 150 Multiplier 151 Smoothing part 152 Binarization calculating part 153 Size detection part

JP 2007-60004 A

Claims (7)

A document size detection device for detecting the size of a document placed on a document table,
A light source for irradiating light on a document placed on the document table and scanning in a first direction parallel to the surface of the document table;
A reading control unit that instructs reading of image data in a determination range that is a predetermined range of one line in a second direction perpendicular to the first direction to which light from the light source is irradiated;
A reading unit that reads the image data in the determination range instructed by the reading control unit based on light incident on the determination range;
A document size detection apparatus comprising: a size detection unit configured to detect a size of the document based on the image data in the determination range.   The reading unit is a CMOS (Complementary Metal Oxide Semiconductor) line sensor having a plurality of photodiodes, and the determination range is based on light incident on a photodiode corresponding to the determination range among the plurality of photodiodes. The document size detection apparatus according to claim 1, wherein the image data is read. A storage unit that stores a plurality of different document sizes and determination ranges for each document size in association with each other;
The reading control unit instructs reading of the image data of each determination range stored in the storage unit,
The reading unit reads the image data of each determination range,
The document size detection apparatus according to claim 1, wherein the size detection unit detects the size of the document based on the image data of each determination range. A smoothing processing unit for smoothing the image data obtained by the reading unit;
4. The document size detection according to claim 1, wherein the size detection unit detects the document size based on the image data smoothed by the smoothing processing unit. 5. apparatus. A binarization processing unit that binarizes the image data obtained by the reading unit;
5. The document size detection according to claim 1, wherein the size detection unit detects the document size based on a value after binarization by the binarization processing unit. 6. apparatus. An amplification processing unit that amplifies the signal of the image data obtained by the reading unit;
6. The document size detection apparatus according to claim 1, wherein the size detection unit detects the document size based on the image data amplified by the amplification processing unit. A document size detection method executed by a document size detection device that detects the size of a document placed on a document table,
An irradiation step of irradiating light on a document placed on the document table by scanning in a first direction parallel to the surface of the document table;
A reading control step for instructing reading of image data in a determination range which is a predetermined range of one line in a second direction perpendicular to the first direction to which light is irradiated;
A reading step of reading the image data in the determination range instructed in the reading control step based on the light incident on the determination range;
A document size detection method comprising: a size detection step of detecting a size of the document based on the image data in the determination range.

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