JP6237536B2 - Sheet conveying apparatus, image processing apparatus, and sheet size determination method - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, an image processing apparatus, and a sheet size determination method.

  In an image processing apparatus such as a scanner, the size of a document may be determined before the image of the document is read. For example, in a configuration including a sheet conveyance device such as an automatic document conveyance device (ADF) that conveys a sheet placed on the sheet placement portion to a reading position, the size of the document placed on the sheet placement portion is determined. Possible image processing devices are known.

  For example, the sheet placement unit of this type of image processing apparatus is provided so as to be movable in the width direction perpendicular to the document conveyance direction, and regulates the position in the width direction of the document placed on the sheet placement unit. A guide member is provided. Then, an electric signal corresponding to the position of the guide member is acquired, so that the size of the document placed on the sheet placement unit is determined (see, for example, Patent Document 1).

JP 2004-131267 A

  By the way, when the user operates the guide member, the electric signal corresponding to the position of the guide member may fluctuate and become unstable. In this case, the determination accuracy of the document size in the image processing apparatus is lowered, and the document image may be read based on an erroneous determination result.

  An object of the present invention is to provide a sheet conveying apparatus, an image processing apparatus, and a sheet size determining method capable of improving the accuracy of determining the size of a sheet placed on a sheet placing section.

  A sheet conveying apparatus according to one aspect of the present invention includes a sheet placement unit, a guide member, a signal acquisition unit, a determination unit, a first size determination unit, and a second size determination unit. The sheet placement unit places a sheet to be conveyed. The guide member is provided so as to be movable in the width direction perpendicular to the conveyance direction of the sheet in the sheet placement portion, and regulates the position in the width direction of the sheet placed on the sheet placement portion. The signal acquisition unit acquires an electrical signal corresponding to the position of the guide member in the sheet placement unit at a predetermined first interval. The determination unit includes a threshold for determining the size of the sheet set in advance based on the value of the electrical signal acquired by the signal acquisition unit and the length in the width direction for each size of the sheet. It is determined whether or not the difference exceeds a preset first reference value. When the determination unit determines that any difference between the value of the electric signal and the threshold value exceeds the first reference value, the first size determination unit determines the sheet according to the value of the electric signal. The size of the sheet placed on the placement unit is determined. A plurality of second size determination units acquired at the first interval when the determination unit determines that a difference between the value of the electrical signal and any one of the threshold values is equal to or less than the first reference value; The size of the sheet placed on the sheet placing portion can be determined according to the average value of the electrical signals.

  An image processing apparatus according to another aspect of the present invention includes a sheet conveying device and an image reading unit. The sheet conveying apparatus includes a sheet placement unit, a guide member, a signal acquisition unit, a determination unit, a first size determination unit, and a second size determination unit. The sheet placement unit places a sheet to be conveyed. The guide member is provided so as to be movable in the width direction perpendicular to the conveyance direction of the sheet in the sheet placement portion, and regulates the position in the width direction of the sheet placed on the sheet placement portion. The signal acquisition unit acquires an electrical signal corresponding to the position of the guide member in the sheet placement unit at a predetermined first interval. The determination unit includes a threshold for determining the size of the sheet set in advance based on the value of the electrical signal acquired by the signal acquisition unit and the length in the width direction for each size of the sheet. It is determined whether or not the difference exceeds a preset first reference value. When the determination unit determines that any difference between the value of the electric signal and the threshold value exceeds the first reference value, the first size determination unit determines the sheet according to the value of the electric signal. The size of the sheet placed on the placement unit is determined. A plurality of second size determination units acquired at the first interval when the determination unit determines that a difference between the value of the electrical signal and any one of the threshold values is equal to or less than the first reference value; The size of the sheet placed on the sheet placing portion can be determined according to the average value of the electrical signals. On the other hand, the image reading unit can read image data from the sheet conveyed by the sheet conveying apparatus based on a determination result of the sheet size by the sheet conveying apparatus.

  A sheet size determination method according to another aspect of the present invention is provided with a sheet placement unit on which a sheet to be conveyed is placed, and the sheet placement unit movably provided in a width direction perpendicular to the sheet conveyance direction. And a guide member that regulates the position in the width direction of the sheet placed on the sheet placement unit, and includes the following first to fourth steps. In the first step, an electrical signal corresponding to the position of the guide member in the sheet placement unit is acquired at a predetermined first interval. The second step includes a threshold for determining a preset sheet size based on the value of the electrical signal acquired in the first step and the length in the width direction for each sheet size. It is determined whether or not the difference exceeds a first reference value set in advance. In the third step, when it is determined in the second step that the difference between the value of the electrical signal and the threshold value exceeds the first reference value, the sheet loading is performed according to the value of the electrical signal. The size of the sheet placed on the placement unit is determined. In the fourth step, when it is determined in the second step that a difference between the value of the electric signal and any one of the threshold values is equal to or less than the first reference value, a plurality of pieces acquired at the first interval are obtained. The size of the sheet placed on the sheet placement unit can be determined according to the average value of the electrical signal.

  According to the present invention, a sheet conveying apparatus, an image processing apparatus, and a sheet size determining method capable of improving the accuracy of determining the size of a sheet placed on the sheet placing section are realized.

FIG. 1 is a diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a system configuration of the image processing apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing a configuration of the ADF of the image processing apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the ADF of the image processing apparatus according to the embodiment of the present invention. FIG. 5 is a flowchart illustrating an example of the size determination process executed by the image processing apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Schematic Configuration of Image Processing Apparatus 10]
First, a schematic configuration of the image processing apparatus 10 according to the embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a schematic cross-sectional view showing the configuration of the image processing apparatus 10. FIG. 3 is a schematic plan view showing the configuration of the ADF 1. FIG. 4 is a diagram showing the size of a document placed on the document placement unit 11 of the ADF 1.

  As shown in FIGS. 1 and 2, the image processing apparatus 10 includes an ADF 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, and an operation display unit 6. The image processing apparatus 10 is a multifunction device having a plurality of functions such as a print function, a facsimile function, or a copy function, in addition to a scan function for reading image data from a document. In the image processing apparatus 10, the configuration including the ADF 1 and the control unit 5 is an example of the sheet conveying apparatus according to the present invention. The present invention is also applicable to image processing apparatuses such as scanner apparatuses, printer apparatuses, facsimile apparatuses, and copiers.

  The image reading unit 2 includes a document table, a reading unit, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device), and can read image data from the document.

  The image forming unit 3 can form an image by electrophotography based on the image data read by the image reading unit 2 or image data input from an information processing apparatus such as an external personal computer. Specifically, the image forming unit 3 includes a photosensitive drum, a charging device, an optical scanning device (LSU), a developing device, a transfer roller, a cleaning device, a fixing roller, a pressure roller, and a paper discharge tray. Then, in the image forming unit 3, an image is formed on the sheet supplied from the paper feeding unit 4, and the sheet after the image formation is discharged to the paper discharge tray. The sheet is a sheet material such as paper, coated paper, postcard, envelope, and OHP sheet.

  The control unit 5 includes control devices such as a CPU, ROM, RAM, and EEPROM (not shown). The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile storage unit in which information such as a control program for causing the CPU to execute various processes is stored in advance. The RAM is a volatile storage unit, and the EEPROM is a non-volatile storage unit. The RAM and the EEPROM are used as a temporary storage memory (working area) for various processes executed by the CPU. Then, the control unit 5 performs overall control of the image processing apparatus 10 by executing various control programs stored in advance in the ROM using the CPU. The control unit 5 may be an electronic circuit such as an integrated circuit (ASIC), and is a control unit provided separately from the main control unit that comprehensively controls the image processing apparatus 10. May be.

  The operation display unit 6 is a display unit such as a liquid crystal display that displays various types of information in response to control instructions from the control unit 5, and an operation key or touch panel that inputs various types of information to the control unit 5 in response to user operations. And so on.

  As shown in FIG. 1, the ADF 1 is an automatic document feeder that includes a document placement section 11, a plurality of transport rollers 12, a document press 13, and a paper discharge section 14. In the ADF 1, each of the transport rollers 12 is driven by a motor (not shown), so that the document placed on the document placement unit 11 passes through the image data reading position by the image reading unit 2 and reaches the paper discharge unit 14. Be transported. As a result, the image reading unit 2 can read image data from a document conveyed by the ADF 1. Here, the document placing portion 11 is an example of a sheet placing portion in the present invention. A document conveyed by the ADF 1 is an example of a sheet in the present invention.

  Here, in the image processing apparatus 10, the size of the document placed on the document placement unit 11 of the ADF 1 is determined. Specifically, as illustrated in FIGS. 2 to 4, the document placement unit 11 of the ADF 1 is provided with guide members 15 </ b> A and 15 </ b> B, a position sensor 16, a first sensor 17, and a second sensor 18.

  The guide members 15 </ b> A and 15 </ b> B are provided to be movable in the width direction 152 perpendicular to the document transport direction 151 in the document placement unit 11, and regulate the position of the document placed in the width direction 152 on the document placement unit 11. To do.

  For example, as shown in FIG. 3, the guide members 15 </ b> A and 15 </ b> B are connected to a rack 153 and a pinion 154 provided inside the document placement portion 11, so that the guide members 15 </ b> A and 15 </ b> B are close to or separated from each other in the width direction 152. It is provided so that it can be linked. Accordingly, the user can operate the guide members 15A and 15B to regulate the position in the width direction 152 of the document placed in accordance with the placement reference position P1 (see FIG. 3) in the document placement portion 11. Is possible. In the document placing portion 11, only one of the guide members 15A and 15B may be provided so as to be movable in the width direction 152, and the other may be provided fixedly.

  The position sensor 16 outputs an electrical signal corresponding to the positions of the guide members 15A and 15B in the document placing portion 11, that is, the distance between the guide members 15A and 15B. For example, the position sensor 16 is an electronic circuit including a variable resistor that changes a resistance value according to the movement of the rack 153 in the width direction 152 or the rotation of the pinion 154. Then, the position sensor 16 outputs an electric signal of voltage or current corresponding to the resistance value of the variable resistor to the control unit 5 according to the control signal input from the control unit 5. Thereby, the control part 5 can detect the separation distance in the width direction 152 of the guide members 15A and 15B based on the electric signal output from the position sensor 16.

  The first sensor 17 outputs an electrical signal corresponding to the presence or absence of a document at the placement reference position P1. For example, as shown in FIGS. 3 and 4, the first sensor 17 is a reflection type optical sensor having a light emitting unit and a light receiving unit arranged on the placement reference position P1. Then, the first sensor 17 outputs an electrical signal corresponding to the presence or absence of the document at the placement reference position P <b> 1 to the control unit 5 in accordance with the control signal input from the control unit 5. Thus, the control unit 5 can detect the presence or absence of a document in the document placement unit 11 based on the electrical signal output from the first sensor 17.

  The second sensor 18 outputs an electrical signal corresponding to the presence or absence of a document at a predetermined determination position P <b> 2 of the document placement unit 11. Specifically, as shown in FIG. 4, the determination position P <b> 2 in the image processing apparatus 10 is the same as the document placement in the Folio size document region placed in the document placement unit 11 in accordance with the placement reference position P <b> 1. This is a position included in an area outside the A4 vertical size document area placed on the placement unit 11. For example, as shown in FIGS. 3 and 4, the second sensor 18 is a reflective optical sensor having a light emitting part and a light receiving part arranged on the determination position P2. Then, the second sensor 18 outputs an electrical signal according to the presence or absence of the document at the determination position P <b> 2 to the control unit 5 in accordance with the control signal input from the control unit 5. Accordingly, the control unit 5 can detect the presence or absence of a document at the determination position P <b> 2 of the document placement unit 11 based on the electric signal output from the second sensor 18.

  On the other hand, the storage unit such as the EEPROM of the control unit 5 stores a plurality of threshold values Th1 to Th3 for determining a preset document size based on the length in the width direction 152 for each document size. ing. Specifically, as shown in FIG. 4, the plurality of threshold values Th <b> 1 to Th <b> 3 are widths for the A3 vertical size, B4 vertical size, A4 vertical size, and B5 vertical size of the document placed on the document placement unit 11. It is set based on the length in the direction 152.

  More specifically, the threshold value Th1 is set between the length (297 millimeters) in the width direction 152 of the A3 vertical document and the length (257 millimeters) in the width direction 152 of the B4 vertical document. For example, the threshold Th1 may be set to an intermediate value (277 millimeters) between the length in the width direction 152 of the A3 vertical document and the length in the width direction 152 of the B4 vertical document.

  The threshold Th2 is set between the length (257 millimeters) in the width direction 152 of the B4 vertical document and the length (210 millimeters) in the width direction 152 of the A4 vertical document. For example, the threshold Th2 may be set to an intermediate value (233.5 millimeters) between the length in the width direction 152 of the B4 vertical document and the length in the width direction 152 of the A4 vertical document.

  The threshold Th3 is set between the length (210 millimeters) in the width direction 152 of the A4 vertical document and the length (182 millimeters) in the width direction 152 of the B5 vertical document. For example, the threshold Th3 may be set to an intermediate value (196 millimeters) between the length in the width direction 152 of the A4 vertical size document and the length in the width direction 152 of the B5 vertical size document.

  Then, the control unit 5 detects the separation distance between the guide members 15A and 15B based on the electrical signal output from the position sensor 16, and compares the detected separation distance with each of the plurality of threshold values Th1 to Th3, and Based on the electrical signal output from the second sensor 18, the size of the document placed on the document placement unit 11 is determined.

  Specifically, when the separation distance exceeds the threshold Th1, the control unit 5 determines that the size of the document is A3 portrait or A4 landscape. When the control unit 5 detects the presence of the document at the determination position P2 based on the electrical signal output from the second sensor 18, the control unit 5 determines the document size as A3 portrait. On the other hand, when detecting the absence of the document at the determination position P2, the control unit 5 determines that the document size is A4 landscape.

  In addition, when the separation distance exceeds the threshold Th2 and is equal to or less than the threshold Th1, the control unit 5 determines that the document size is B4 portrait or B5 landscape. When the control unit 5 detects the presence of the document at the determination position P <b> 2 based on the electrical signal output from the second sensor 18, the control unit 5 determines the document size to be B4 portrait. On the other hand, when detecting the absence of the document at the determination position P2, the control unit 5 determines the document size to be B5 landscape.

  In addition, when the separation distance exceeds the threshold Th3 and is equal to or less than the threshold Th2, the control unit 5 determines that the document size is Folio or A4 portrait. When the control unit 5 detects the presence of the document at the determination position P2 based on the electrical signal output from the second sensor 18, the control unit 5 determines the size of the document as Folio. On the other hand, when detecting the absence of the document at the determination position P2, the control unit 5 determines that the document size is A4 portrait.

  Then, when the separation distance is equal to or smaller than the threshold Th3, the control unit 5 determines that the document size is B5 portrait.

  By the way, when the user operates the guide members 15A and 15B, the electrical signal output from the position sensor 16 according to the positions of the guide members 15A and 15B may fluctuate and become unstable. In this case, the accuracy of determining the size of the document placed on the document placement unit 11 is lowered, and the image of the document may be read based on an erroneous determination result. In contrast, the image forming apparatus 10 can improve the accuracy of determining the size of the document placed on the document placement unit 11 as described below.

  Specifically, a size determination program for causing the CPU to execute a size determination process (see FIG. 5) described later is stored in advance in the ROM or the EEPROM of the control unit 5. The size determination program is recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and is read from the recording medium and installed in a storage unit such as the EEPROM of the control unit 5. It may be.

  Then, as shown in FIG. 2, the control unit 5 includes a first document detection unit 51, a signal acquisition unit 52, a determination unit 53, a second document detection unit 54, a first size determination unit 55, and a second size determination unit 56. And a display control unit 57. Specifically, the control unit 5 uses the CPU to execute the size determination program stored in the ROM, whereby the first document detection unit 51, the signal acquisition unit 52, the determination unit 53, and the second document. It functions as a detection unit 54, a first size determination unit 55, a second size determination unit 56, and a display control unit 57. Here, the first document detection unit 51 is an example of the first sheet detection unit in the present invention. The second document detection unit 54 is an example of a second sheet detection unit in the present invention.

  The first document detection unit 51 detects the placement of the document on the document placement unit 11. Specifically, the first document detection unit 51 periodically transmits a control signal to the first sensor 17 to output an electrical signal corresponding to the presence or absence of the document at the placement reference position P1. Then, the first document detection unit 51 detects the placement of the document on the document placement unit 11 by monitoring the electrical signal output from the first sensor 17.

  The signal acquisition unit 52 acquires electrical signals corresponding to the positions of the guide members 15A and 15B in the document placement unit 11 at a predetermined first interval. Specifically, the signal acquisition unit 52 transmits a control signal to the position sensor 16 at the first interval to output an electrical signal corresponding to the separation distance between the guide members 15A and 15B.

  Here, the first interval is set to an appropriate value in consideration of a variation period when the electric signal output from the position sensor 16 varies. For example, the first interval may be less than or equal to one half of the fluctuation period when the electric signal output from the position sensor 16 fluctuates.

  The determination unit 53 determines whether or not the difference between the value of the electrical signal acquired by the signal acquisition unit 52 and each of the threshold values Th1 to Th3 exceeds a preset first reference value.

  Here, the first reference value is set to an appropriate value in consideration of the amplitude and the like when the electric signal output from the position sensor 16 fluctuates. For example, the first reference value may be a value that exceeds the maximum amplitude when the electric signal output from the position sensor 16 varies.

  In addition, the determination unit 53 sets the value of the electric signal acquired by the signal acquisition unit 52 and each of the threshold values Th1 to Th3 at a second interval predetermined from the time when the first document detection unit 51 detects the placement of the document. It is determined whether or not the difference exceeds the first reference value. For example, the second interval is set to an appropriate value between 0.1 second and 10 seconds.

  The second document detection unit 54 detects the presence or absence of a document at the determination position P2 of the document placement unit 11. Specifically, the second document detection unit 54 transmits a control signal to the second sensor 18 to output an electrical signal corresponding to the presence or absence of the document at the determination position P2. Then, the second document detection unit 54 detects the presence or absence of a document at the determination position P <b> 2 based on the electrical signal output from the second sensor 18.

  When the first size determination unit 55 determines that the difference between the electric signal value acquired by the signal acquisition unit 52 and each of the threshold values Th1 to Th3 exceeds the first reference value by the determination unit 53, The size of the document placed on the document placement unit 11 is determined according to the value of the electrical signal and the detection result by the second document detection unit 54. Specifically, the first size determination unit 55 detects the separation distance between the guide members 15A and 15B based on the electrical signal acquired by the signal acquisition unit 52, and the detected separation distance and a plurality of threshold values Th1 to Th3. The size of the document placed on the document placement unit 11 is determined based on the comparison results with each other and the detection result by the second document detection unit 54. The first size determination unit 55 may determine the size of the document placed on the document placement unit 11 according to the value of the electrical signal.

  When it is determined by the determination unit 53 that the difference between the value of the electrical signal acquired by the signal acquisition unit 52 and any one of the threshold values Th1 to Th3 is equal to or less than the first reference value, the second size determination unit 56 The size of the document placed on the document placement unit 11 is determined according to the average value of the plurality of electrical signals acquired at the first interval by the signal acquisition unit 52 and the detection result by the second document detection unit 54. Is possible. Specifically, the second size determination unit 56 detects the separation distance between the guide members 15 </ b> A and 15 </ b> B based on the average value of the plurality of electrical signals acquired at the first interval by the signal acquisition unit 52. Based on the comparison result between the separation distance and each of the plurality of threshold values Th1 to Th3 and the electrical signal output from the second sensor 18, the size of the document placed on the document placement portion 11 is determined. The second size determination unit 56 determines the size of the document placed on the document placement unit 11 according to the average value of the plurality of electrical signals acquired at the first interval by the signal acquisition unit 52. May be.

  Here, the number of electrical signals used for averaging by the second size determination unit 56 is set to an appropriate value in consideration of the variation period when the electrical signal output from the position sensor 16 varies, the first interval, and the like. Is done. For example, the number of electrical signals used for averaging by the second size determination unit 56 may be less than or equal to a value obtained by dividing the variation period when the electrical signal output from the position sensor 16 varies by the first interval. .

  In addition, the second size determination unit 56, when the difference between the maximum value and the minimum value of the plurality of electrical signals acquired at the first interval by the signal acquisition unit 52 exceeds a preset second reference value The size of the document placed on the document placement unit 11 is not determined.

  Here, the second reference value is set to an appropriate value in consideration of the amplitude when the electric signal output from the position sensor 16 fluctuates. For example, the second reference value may be set to a value that is twice or less the maximum amplitude when the electric signal output from the position sensor 16 fluctuates.

  The display control unit 57 causes the operation display unit 6 to display the determination result by the first size determination unit 55 or the second size determination unit 56 according to the determination result by the determination unit 53. Specifically, the display control unit 57 determines that the difference between the value of the electrical signal acquired by the signal acquisition unit 52 and each of the threshold values Th1 to Th3 exceeds the first reference value by the determination unit 53. In addition, the determination result by the first size determination unit 55 is displayed on the operation display unit 6. The display control unit 57 also determines that the difference between the value of the electrical signal acquired by the signal acquisition unit 52 and any one of the threshold values Th1 to Th3 is equal to or less than the first reference value by the determination unit 53. The determination result by the second size determination unit 56 is displayed on the operation display unit 6.

[Size determination processing]
Hereinafter, an example of the size determination process performed by the control unit 5 according to the size determination program in the image processing apparatus 10 will be described with reference to FIG. Here, steps S1, S2,... Represent processing procedure (step) numbers executed by the control unit 5.

<Step S1>
First, in step S <b> 1, the control unit 5 determines whether or not the document placement on the document placement unit 11 is detected. Here, the process of step S <b> 1 is executed by the first document detection unit 51 of the control unit 5.

  If the control unit 5 determines that the document placement on the document placement unit 11 has been detected (Yes side of S1), the control unit 5 shifts the process to step S2. If the placement of the document on the document placement unit 11 is not detected (No in S1), the control unit 5 waits for the detection of the placement of the document on the document placement unit 11 in step S1.

<Step S2>
In step S <b> 2, the control unit 5 acquires electrical signals corresponding to the positions of the guide members 15 </ b> A and 15 </ b> B in the document placement unit 11 at the first interval. Here, the process of step S <b> 2 is an example of the first step in the present invention, and is executed by the signal acquisition unit 52 of the control unit 5.

<Step S3>
In step S3, the control unit 5 determines whether or not the difference between the value of the electrical signal acquired in step S2 and each of the threshold values Th1 to Th3 exceeds the first reference value. Here, the process of step S3 is an example of the second step in the present invention, and is executed by the determination unit 53 of the control unit 5.

  Here, when the control unit 5 determines that the difference between the value of the electrical signal acquired in step S2 and each of the threshold values Th1 to Th3 exceeds the first reference value (Yes side of S3), the process is performed. The process proceeds to S4. If the difference between the value of the electrical signal acquired in step S2 and any one of the threshold values Th1 to Th3 is equal to or less than the first reference value (No side of S3), the control unit 5 moves the process to step S31. Let

<Step S4>
In step S <b> 4, the control unit 5 detects the presence or absence of a document at the determination position P <b> 2 of the document placement unit 11. Here, the process of step S4 is executed by the second document detection unit 54 of the control unit 5.

<Step S5>
In step S5, the control unit 5 determines the size of the document placed on the document placement unit 11 according to the value of the electrical signal acquired in step S2 and the detection result in step S4. Then, the control unit 5 stores the determination result in the RAM. Note that if the processing of step S5 or step S34 described later has already been performed and the document size determination result is stored in the RAM, the control unit 5 stores the new determination result in the RAM. The judgment result is overwritten and stored. Here, the process of step S5 is an example of the third step in the present invention, and is executed by the first size determination unit 55 of the control unit 5.

<Step S6>
In step S6, the control unit 5 causes the operation display unit 6 to display the determination result in step S5. Here, the process of step S <b> 6 is executed by the display control unit 57 of the control unit 5.

<Step S31>
On the other hand, if it is determined in step S3 that the difference between the value of the electrical signal acquired in step S2 and any one of the threshold values Th1 to Th3 is equal to or less than the first reference value, the process of step S31 is executed. The In step S31, the control unit 5 determines whether or not the difference between the maximum value and the minimum value of the plurality of electrical signals acquired at the first interval in step S2 exceeds the second reference value. Here, the process of step S <b> 31 is executed by the second size determination unit 56 of the control unit 5.

  Here, when the control unit 5 determines that the difference between the maximum value and the minimum value of the plurality of electrical signals acquired at the first interval in step S2 exceeds the second reference value (Yes side of S31), The process proceeds to step S7. Thereby, when the guide members 15A and 15B are operated by the user, the processing in step S32 and the subsequent steps is executed, so that the size of the document is erroneously detected and the erroneously detected size is not displayed. The If the difference between the maximum value and the minimum value of the plurality of electrical signals acquired at the first interval in step S2 is equal to or less than the second reference value (No in S31), the control unit 5 performs the process. The process proceeds to step S32.

<Step S32>
In step S32, the control unit 5 calculates the average value of the plurality of electrical signals acquired at the first interval in step S2.

<Step S33>
In step S33, the control unit 5 detects the presence or absence of a document at the determination position P2 of the document placement unit 11 as in step S4. Here, the process of step S33 is executed by the second document detection unit 54 of the control unit 5.

<Step S34>
In step S34, the control unit 5 determines the size of the document placed on the document placement unit 11 according to the average value of the plurality of electrical signals calculated in step S32 and the detection result in step S33. . Then, the control unit 5 stores the determination result in the RAM. Note that if the processing of step S5 or step S34 has already been performed and the document size determination result is stored in the RAM, the control unit 5 determines that the new determination result is stored in the RAM. Overwrite the result and memorize it. Here, the process of step S34 is an example of a fourth step in the present invention, and is executed by the second size determination unit 56 of the control unit 5.

<Step S35>
In step S35, the control part 5 displays the determination result in step S34 on the operation display part 6. Here, the process of step S <b> 35 is executed by the display control unit 57 of the control unit 5.

<Step S7>
In step S7, the control unit 5 determines whether or not a predetermined time corresponding to the second interval has elapsed since the execution of the process in step S3. Here, the process of step S7 is executed by the determination unit 53.

  Here, when the control unit 5 determines that the time corresponding to the second interval has elapsed since the execution of the process in step S3 (Yes side of S7), the control unit 5 shifts the process to step S3. If the time corresponding to the second interval has not elapsed since the execution of the process in step S3 (No side in S7), the control unit 5 shifts the process to step S8.

<Step S8>
In step S <b> 8, the control unit 5 determines whether or not an operation for executing an image reading process for reading an image of a document placed on the ADF 1 in the operation display unit 6 has been performed.

  If the control unit 5 determines that the operation for executing the image reading process has been performed on the operation display unit 6 (Yes in S8), the control unit 5 shifts the process to step S9. If the execution operation of the image reading process is not performed on the operation display unit 6 (No side in S8), the control unit 5 returns the process to step S7 and elapses of time corresponding to the second interval. Alternatively, an operation for executing the image reading process on the operation display unit 6 is awaited.

  As a result, the size of the document placed on the document placement unit 11 after the user places the document on the document placement unit 11 and before the operation display unit 6 performs the image reading processing operation. It is displayed on the operation display unit 6 in real time. Therefore, the user can confirm the determination result of the document size by the control unit 5 before performing the operation of executing the image reading process, and the image reading process is performed based on the determination result contrary to the user's intention. Is suppressed from being executed.

<Step S9>
In step S9, the control unit 5 executes the image reading process. Here, the control unit 5 executes the image reading process based on the determination result of the document size stored in the RAM. For example, the control unit 5 controls the operation of the reading unit of the image reading unit 2 based on the determination result of the document size stored in the RAM.

  Thus, in the size determination process, the difference between the value of the electric signal acquired by the signal acquisition unit 52 and any one of the threshold values Th1 to Th3 used for determining the size of the document is equal to or less than the first reference value. In this case, the size of the document is determined based on the average value of the plurality of electrical signals acquired at the first interval by the signal acquisition unit 52. As a result, when the variation in the electrical signal output from the position sensor 16 affects the determination result of the document size, the effect due to the variation in the electrical signal is reduced or eliminated. Accordingly, it is possible to improve the accuracy of determining the size of the document placed on the document placement unit 11.

  The present invention may be applied to the paper feeding unit 4 that supplies the sheet to the image forming unit 3. For example, it is conceivable that the present invention is applied to the paper feed unit 4 in a configuration in which the paper feed unit 4 of the image processing apparatus 10 includes a manual tray on which the sheet supplied to the image forming unit 3 is placed. In this case, an apparatus including the sheet feeding unit 4 and the control unit 5 is another example of the sheet conveying apparatus in the present invention. The manual feed tray is another example of the sheet placing portion in the present invention.

1: ADF
11: Document placement unit 15A, 15B: Guide member 16: Position sensor 17: First sensor 18: Second sensor 2: Image reading unit 3: Image forming unit 4: Paper feeding unit 5: Control unit 51: First document Detection unit 52: signal acquisition unit 53: determination unit 54: second document detection unit 55: first size determination unit 56: second size determination unit 57: display control unit 6: operation display unit 10: image processing apparatus

Claims (7)

A sheet placement section on which a sheet to be conveyed is placed;
A guide member provided in the sheet placement portion so as to be movable in a width direction perpendicular to the conveyance direction of the sheet, and regulating a position of the sheet placed in the sheet placement portion in the width direction;
A signal acquisition unit for acquiring an electrical signal corresponding to a position of the guide member in the sheet placement unit at a predetermined first interval;
The difference between the plurality of thresholds each for judging the size of the sheets set in advance based on the length in the width direction of each size of the value of the electrical signal sheets acquired by the signal acquiring unit A determination unit for determining whether or not a first reference value set in advance is exceeded;
If the difference between the threshold value of each value of one of said electrical signal is determined to both greater than the first reference value by the determining unit, the mounting to the seat mounting portion in accordance with the value of the electrical signal A first size determining unit that determines the size of the sheet placed;
When the determination unit determines that the difference between the value of the electric signal and any one of the threshold values is equal to or less than the first reference value, the average value of the plurality of electric signals acquired at the first interval is set. A second size determination unit capable of determining the size of the sheet placed on the sheet placement unit in response,
Equipped with a,
The plurality of threshold values are an intermediate value between the length in the width direction of the A3 vertical size sheet and the length in the width direction of the B4 vertical size sheet, and the length in the width direction of the B4 vertical size sheet and A4. An intermediate value between the length in the width direction of the sheet of vertical size, and an intermediate value of the length in the width direction of the sheet of A4 vertical size and the length in the width direction of the sheet of B5 vertical size,
The first reference value, Ru value der exceed the maximum amplitude at the time of variation of the electrical signal acquired by the signal acquiring unit sheet conveying apparatus. A first sheet detection unit that detects placement of the sheet on the sheet placement unit;
A display control unit that causes the display unit to display a determination result by the first size determination unit or the second size determination unit according to a determination result by the determination unit;
Whether the difference between the value of the electrical signal and the threshold exceeds the first reference value at a predetermined second interval from the time when the determination unit detects the placement of the sheet by the first sheet detection unit. The sheet conveying apparatus according to claim 1, which determines whether or not. When the difference between the maximum value and the minimum value of the plurality of electric signals acquired at the first interval exceeds the second reference value set in advance, the sheet placement unit Without determining the size of the sheet placed on the
The sheet conveying apparatus according to claim 2, wherein the second reference value is a value equal to or less than twice the maximum amplitude when the electric signal obtained by the signal obtaining unit varies . A second sheet detecting unit for detecting the presence or absence of the sheet at a predetermined position of the sheet placing unit;
The first size determination unit determines the size of the sheet according to the value of the electrical signal and the detection result by the second sheet detection unit,
The sheet conveying apparatus according to claim 1, wherein the second size determining unit determines the size of the sheet according to an average value of a plurality of the electrical signals and a detection result by the second sheet detecting unit. .   An image processing apparatus comprising: the sheet conveying apparatus according to claim 1; and an image reading unit capable of reading image data from the sheet conveyed by the sheet conveying apparatus.   The image processing apparatus according to claim 5, further comprising an image forming unit capable of forming an image based on image data read by the image reading unit. A sheet placement unit on which a sheet to be conveyed is placed; and the sheet placed on the sheet placement unit, provided to be movable in a width direction perpendicular to the sheet conveyance direction in the sheet placement unit. A sheet size determination method executed by a sheet conveying apparatus including a guide member that regulates the position in the width direction of
A first step of acquiring an electrical signal corresponding to a position of the guide member in the sheet placing portion at a predetermined first interval;
The difference between the plurality of thresholds each for judging the size of the sheets set in advance based on the length in the width direction of each size of the value of the electrical signal obtained by the first step sheets A second step of determining whether or not a preset first reference value is exceeded;
If the difference between the threshold value of each value of one of said electrical signal is determined to both greater than the first reference value by said second step, to the seat mounting portion in accordance with the value of the electrical signal A third step of determining the size of the placed sheet;
The average value of the plurality of electrical signals acquired at the first interval when the difference between the value of the electrical signal and one of the threshold values is less than or equal to the first reference value by the second step. And a fourth step capable of determining the size of the sheet placed on the sheet placement unit according to
Only including,
The plurality of threshold values are an intermediate value between the length in the width direction of the A3 vertical size sheet and the length in the width direction of the B4 vertical size sheet, and the length in the width direction of the B4 vertical size sheet and A4. An intermediate value between the length in the width direction of the sheet of vertical size, and an intermediate value of the length in the width direction of the sheet of A4 vertical size and the length in the width direction of the sheet of B5 vertical size,
The sheet size determination method, wherein the first reference value is a value that exceeds a maximum amplitude at the time of fluctuation of the electrical signal acquired in the first step .

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