JP4446927B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus capable of detecting the size of a document to be read.

  Conventionally, an image forming apparatus such as a copying machine is equipped with an image reading device for reading image information of a document, and there are many types of methods for detecting the size of a document to be read by the image reading device. is there.

  For example, when an image of a document is read, an openable and closable cover is provided to cover the document, and a predetermined pattern is attached to the cover, and image information obtained by reading whether or not this pattern is hidden by the document There is an image reading apparatus that detects the size of a document by analyzing the above (see Patent Document 1). Hereinafter, this image reading apparatus is referred to as a first conventional example.

  Further, there is an image reading apparatus that has a light source for detecting the size of a document and detects the size of the document by reading a shadow generated on the edge of the document illuminated by the light source (see Patent Document 2). ). Hereinafter, this image reading apparatus is referred to as a second conventional example.

  Furthermore, it has a light source that emits a spot light for detecting the size of the document, and receives the spot light reflected by the document or reflected by the document cover by a position detecting element (PSD). An image reading apparatus that detects the size of a document is widely known. Hereinafter, this image reading apparatus is referred to as a third conventional example.

Of the methods for detecting the size of the document as described above, the second or third conventional example requires a dedicated light source, and for example, a cold cathode fluorescent tube (CCFT) is used as the light source. A Fluorescent Tube) or a white light emitting diode (LED) is used. These light sources have relatively low power consumption and can emit strong light.
JP 2000-66712 A JP 2003-244403 A Japanese Patent No. 2543825

  However, in the second or third conventional example, since the dedicated light source must be installed at an accurate position, the configuration is complicated and the cost is increased. In this regard, in the first conventional example, a dedicated light source is unnecessary, but it is difficult to accurately analyze the image. For example, in the first conventional example, erroneous detection may be performed when the pattern of the document is similar to the pattern of the cover.

  In the second or third conventional example, since a dedicated light source cannot be omitted, a certain amount of power is required to detect the document size. In this regard, if external light such as illumination light in the room is used as a light source, the above power will not be consumed, but the amount and direction of external light are indefinite depending on the installation environment of the apparatus, so the size of the document is reduced. It is extremely difficult to use external light directly for detection.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that can accurately detect the document size with a simple and low-cost configuration.

  Another object of the present invention is to provide an image reading apparatus in which the power of the light source is not consumed for detecting the document size by indirectly using external light or light for reading the document image. Objective.

A first invention is an image reading apparatus capable of detecting the size of a document to be read,
A reading unit that includes a predetermined light source and optically reads an image of the document;
A background unit disposed in the vicinity of the surface opposite to the document surface to be read by the reading unit, and a phosphorescent material disposed on the surface of the document;
Control means for detecting the size of the document based on the light emitted from the phosphorescent material of the background means ,
The background means absorbs light energy from the light source;
The reading unit alternately repeats an operation of reading the image of the document halfway after turning on the light source and an operation of receiving light emitted from the phosphorescent material of the background unit after turning off the light source, Scan the original image,
The control unit, based on the light from the light-storing material received by said reading means and that you detect the size of the document.

According to a second invention, in the first invention,
The background means absorbs light from the light source partially blocked by the document.

According to a third invention, in the first or second invention,
The predetermined light source is a light source for reading an image of the document by the reading unit.

According to a fourth invention, in any one of the first to third inventions,
  The reading unit includes an exposure scanning unit that reads an image of the document in a predetermined main scanning direction or receives light from the phosphorescent material, and moves the exposure scanning unit at a constant speed in a predetermined sub-scanning direction. The operation of reading the image of the original and the operation of receiving light from the phosphorescent substance are alternately repeated.

A fifth invention is an image reading apparatus according to any one of the first invention to the fourth invention;
An image forming apparatus comprising: an image forming unit configured to form an image based on an image of the original read by the image reading apparatus on a predetermined medium corresponding to the size of the original detected by the image reading apparatus. .

According to the first aspect of the invention, since the size of the document is detected based on the light emitted from the phosphorescent material disposed on the surface of the background unit with respect to the document, the size of the document can be reduced with a simple and low-cost configuration. Accurate detection can be performed.
In addition, since the phosphorescent material of the background means absorbs light energy from a predetermined light source provided inside the device, the light emitted from the phosphorescent material can be controlled by accurately controlling the light amount and lighting time of the light source. Can be easily controlled. Therefore, by accurately detecting the amount of light, it is possible to accurately detect the document size with a simple and low-cost configuration.
Further, since the reading means receives light emitted from the phosphorescent material of the background means when the original image is not read, it is not necessary to provide a new light detecting means for detecting the original size, and it is simple and low cost. With this configuration, it is possible to accurately detect the document size.
Furthermore, the reading means alternately repeats the operation of reading the original image after turning on the light source incorporated therein and the operation of receiving the light emitted from the phosphorescent material of the background means after the light source is turned off. When reading a document image while moving it, the document size can be accurately detected with a simple and low-cost configuration in which the light source is repeatedly turned on and off without changing the moving speed. The power consumption required by the light source for detecting the document size can be eliminated.
In addition, since the reading unit receives light emitted from the phosphorescent material of the background unit after the light source is turned off during the operation of reading the document image, the phosphorescent material can absorb the light that is turned on to read the image. it can. Therefore, a simple and low-cost configuration can be achieved, and power consumption required by the light source for detecting the document size can be eliminated.

According to the second aspect of the invention, since the phosphorescent material of the background means absorbs light from the light source partially blocked by the manuscript, the background means of phosphorescent material absorbs light from the light source not obstructed by the manuscript. In contrast, when the original is a thin material, the contrast between light and dark becomes higher because the portion blocked by the original becomes darker. As a result, the document size detection accuracy can be increased.

According to the third aspect , since the phosphorescent material of the background unit absorbs the light energy from the light source for reading the document image by the reading unit, it is not necessary to provide a new light source for detecting the document size. Further, by accurately detecting the light quantity, it is possible to accurately detect the document size with a simple and low-cost configuration.

According to the fourth aspect of the invention, the operation of reading the image of the document and the operation of receiving the light from the phosphorescent substance are alternately repeated while the exposure scanning unit is moved, so that the light source is moved while the exposure scanning unit is moved. It is possible to achieve a simple and low-cost configuration that simply repeats turning on and off. In general, the exposure scanning means that moves at a constant speed after a predetermined time has elapsed from the start of movement, especially when moving at a high speed, is difficult to rapidly accelerate or decelerate, typically moves at a constant speed. The control to be performed is suitable.

According to the fifth aspect, an image forming apparatus including the image reading apparatus according to any one of the first to fourth aspects can be realized.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
<1. Overall Configuration of Image Forming Apparatus>
FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 is provided with a paper stack unit 2 on the left side of the drawing, and from the upper part on the right side to the lower side, an original reading unit (original image reading means) 3, a main body tray 5, An image forming unit (image forming unit) 6 and a paper feeding unit 7 are provided.

  As shown in FIG. 1, the document reading unit 3 has a document placement table made of transparent glass or the like on the upper surface, and a lower housing that houses a scanner optical system and a document size detector 200 below the document placement table. And an upper part provided with an automatic document feeder (hereinafter referred to as “ADF” (Auto Document Feeder)) 10 having a document cover 11 for pressing the document placed on the document placing table from above. It consists of a housing. The detailed configuration of the ADF 100 will be described later. The end of the upper casing is pivotably connected to the end of the lower casing by a hinge, and the upper casing opens upward with the hinge as a pivot.

  Here, a phosphorescent material (also referred to as a luminescent coating) is applied to the surface of the document cover 11 that should come into contact with the document when the upper housing is closed. The light stored in the phosphorescent material is partially blocked by the document and detected by the document size detector 200. As a result, the document size is detected. This point will also be described later.

  The scanner optical system housed in the lower housing includes an exposure scanning unit 13 including an exposure light source 131, a plurality of reflecting mirrors 14, an imaging lens 15, and a charge coupled device (hereinafter referred to as “CCD” (Charge Coupled Device). )) 16 is provided. The CCD 16 may be a photoelectric conversion element other than a CCD. The exposure scanning unit 13 includes an exposure light source 131 such as a lamp, a concave mirror for irradiating light to a predetermined position of the document placed on the document placement table, and a plurality of mirrors for changing the optical path. Including. The light obtained by being reflected from the exposure light source 131 of the exposure scanning unit 13 to the original is guided to the CCD 16 through the imaging lens 15 from the two reflecting mirrors 14 arranged so that the reflecting surfaces are orthogonal to each other. Further, the exposure scanning unit 13 can be moved along the Y direction by a driving mechanism (not shown). An exposure scanning unit 13 'indicated by a dotted line in the drawing indicates a position when the exposure scanning unit 13 has moved to the maximum in the Y direction. Furthermore, a document size detector 200 that detects the size of the document placed on the document placement table is disposed in the lower housing. The detailed configuration of the document reading unit 3 as described above will be described later.

  As shown in FIG. 1, the image forming unit 6 includes a photoconductor 17 that forms a drum shape and rotates in the direction of an arrow. Further, around the photoconductor 17, along the direction of the arrow, the developing device 18, the transfer charger 19, a cleaning device (not shown), the static eliminator 20, the main charger 21, and a laser scanning unit (hereinafter “ (Abbreviated as “LSU”) 22.

  The document image data read by the CCD 16 is supplied to the LSU 22 after being subjected to predetermined image processing. The LSU 22 irradiates the image data of the original on the surface of the photoconductor 17 as laser light to form an electrostatic latent image. The developing device 18 develops the electrostatic latent image into a visible image with toner. The transfer charger 19 transfers the toner image formed on the surface of the photoreceptor 17 by development to the paper P. The cleaning device removes residual toner on the surface of the photoconductor 17. The static eliminator 20 removes residual charges on the surface of the photoreceptor 17. The main charger 21 charges the photoconductor 17 to a predetermined potential. In addition, since these structures are well known, detailed description is abbreviate | omitted.

  The paper feed unit 7 includes a paper cassette 31 that stores a plurality of papers P. At the leading end position of the paper cassette 31 in the paper output direction, an entrance roller 32 and a paper separation roller 33 for delivering the paper P are provided.

  As the paper transport path, the paper feed unit 7 is provided with a cassette-side paper output path 34. Here, the side from which the paper P flows out (from the paper cassette 31) in the paper transport path is referred to as the upstream side, and the side from which the paper P flows (to each paper discharge tray) is referred to as the downstream side. A paper separation roller 33 is provided at the upstream end of the cassette-side paper output path 34. Further, as the paper transport path, the image forming unit 6 is provided with a manual paper feed path 35, a main transport path 36, a reverse transport path 37, a paper discharge transport path 38, and a paper stack transport path 39.

  A paper separation roller 40 is provided at the upstream end of the manual paper feed path 35, and a manual feed tray 41 and a drawing roller 42 are provided in the vicinity thereof. The downstream end of the cassette-side paper exit path 34 and the manual paper feed path 35 and one end of the reverse transport path 37 join to be connected to the upstream end of the main transport path 36. . The main conveyance path 36 extends upward, merges with the other end of the reverse conveyance path 37 in the vicinity of the downstream end, and further branches into a discharge conveyance path 38 and a paper stack conveyance path 39 on the downstream side. is doing.

  A registration roller 43 is provided at the upstream end of the main conveyance path 36, and a fixing device 44 that heat-compresses the toner image on the paper P at a predetermined position downstream of the transfer charger 19 in the main conveyance path 36. Is provided.

  A paper discharge roller 45 that discharges the paper P to the main body tray 5 is provided at the downstream end of the paper discharge conveyance path 38. A paper discharge roller 45 is disposed at a predetermined position on the upstream side of the paper discharge roller 45. Is provided with a paper discharge detection switch (not shown) for detecting the passage of the paper. Further, a switching gate 46 for switching the traveling direction of the paper P to any one of the transport paths is provided at a branch portion between the paper discharge transport path 38 and the paper stack transport path 39.

  As shown in FIG. 1, the paper stack conveyance path 39 guides the paper P on which an image has been formed to the paper stack unit 2. The sheet stack conveyance path 39 is constituted by a roller pair in which a roller is pressed against the conveyance roller 47. The transport roller 47 is formed of a general rubber roller, and a plurality of the transport rollers 47 are arranged at an appropriate interval in the transport direction of the paper P.

  Two discharge paths (not shown) provided in the paper stack unit 2 are connected to the downstream end of the paper stack conveyance path 39. One of the two discharge paths guides the paper P to a post-processing device (not shown) that performs predetermined post-processing (for example, stapling or offset processing), and the post-processed paper P can be moved up and down as appropriate. The paper is discharged to a (discharge tray) 59. Further, the sheet P conveyed on the other of the discharge paths is discharged to the stack tray 59 without being guided to the post-processing device.

<2. Detailed Configuration and Operation of Document Reading Unit>
As shown in FIG. 1, the document reading unit 3 is configured such that a document set in advance in the ADF 100 of the upper casing is automatically sent, or the upper casing is opened by a user of the apparatus and the document in the lower casing is scanned. By placing the document on the mounting table, the image of the target document is read by the scanner optical system of the lower housing. First, the operation of the document reading unit 3 when a document is placed on the document placing table by the user, in particular, the document size detection operation using the document cover 11 will be described in detail.

  FIG. 2 is a perspective view schematically showing the vicinity of the document reading unit 3 in the image forming apparatus with the upper housing opened. As shown in FIG. 2, a document cover 11 and a fixed platen unit 110 (to be described later) of the ADF 100 are provided on the lower surface of the upper housing. Further, a document placing table 12 is disposed on the upper surface of the lower housing at a position facing the document cover 11 with the upper housing closed, and the ADF 100 is disposed at a position facing the fixed platen portion 110 in the same state. The transmission part 120 is arranged. Therefore, since the document cover 11 and the fixed platen unit 110 are arranged on the opposite side of the exposure scanning unit 13 with the document interposed therebetween, they function as background means for the document. Usually, since the original is white, these are also colored in white, so that the peripheral portion (boundary portion) of the original becomes inconspicuous at the time of image reading. The upper housing and the lower housing on the left side of the figure are provided with discharge rollers 105 of the ADF 100, and the operation will be described later.

  Also, a document cover opening / closing sensor 150 including a contact switch is provided in the vicinity of the pivot point of the upper and lower casings, and whether the upper casing is opened upward or closed. Is detected. The detection result is given to a control unit (not shown). The document cover opening / closing sensor 150 may have a known structure that can detect whether the upper housing is opened upward.

  Further, the document table 12 and the transmission part 120 are both made of glass here, and the exposure scanning unit 13 moves in the Y direction shown in FIG. Hereinafter, this Y direction is referred to as a sub-scanning direction. Further, the light from the exposure scanning unit 13 is given to the CCD 16 through a reduction reading optical system composed of a reflecting mirror 14 and an imaging lens 15 (not shown in FIG. 1). The CCD 16 is arranged in a line along the X direction shown in the figure, and reads the received light. Hereinafter, this X direction is referred to as a main scanning direction. The image of the document placed on the document placement table by the user is acquired by the reading operation in the main scanning direction and the sub scanning direction.

  Here, Luminova (registered trademark of Nemoto Special Chemical Co., Ltd.), which is a phosphorescent substance, is applied to the surfaces of the document cover 11 and the fixed platen unit 110. Since this Luminova (registered trademark) is well known (see, for example, Patent Document 3), detailed description thereof is omitted. This Luminova (registered trademark) is a high-intensity, long-afterglow phosphor that does not contain radioactive materials. Light emission (absorption) of light energy and emission of absorbed energy (hereinafter referred to as this emitted light) "Afterglow") can be repeated any number of times. Therefore, when the upper casing is opened upward, the document cover 11 absorbs external light such as room illumination light, so that afterglow occurs only for a predetermined period even when the upper casing is closed. . The document size detector 200 detects the size of the document placed on the document placement table 12 by using the afterglow. Hereinafter, a detailed configuration of the document size detector 200 will be described.

  The document size detector 200 includes a known position detection element (hereinafter referred to as “PSD”) and a lens. When the upper housing is closed, the document size detector 200 is partially formed by the document placed on the document placement table 12. Afterglow from the blocked document cover 11 is received.

  FIG. 3 is a schematic view of the PSD as viewed from above in the vertical direction with respect to the document table 12. The PSD 210 shown in FIG. 3 has uniform (P-type or N-type) resistance layers formed on both surfaces of a high-resistance semiconductor substrate, and signal extraction electrodes 211a to 211d are provided at both ends of these resistance layers, respectively. Is provided. Since the PSD 210 is formed with a PN junction in a direction perpendicular to the light receiving surface 212, when afterglow from the document cover 11 is applied to the light receiving surface 212, a photocurrent is generated by the photovoltaic effect. This photocurrent is divided by the resistance layer in inverse proportion to the distance to the electrodes 211a to 211d and taken out from these electrodes 211a to 211d. Such a PSD 210 is called a double-sided two-dimensional PSD. A similar configuration can be realized by combining two one-dimensional PSDs.

  Here, in the document cover corresponding area 213 indicated by a one-dot chain line in FIG. 3, the lens included in the document size detector 200 causes afterglow from the document cover 11 when there is no document on the document table 12. This is the area that should be given. A hatched area in the document cover corresponding area 213 indicates an area to which afterglow from the document cover 11 is to be given when a certain document is placed on the document placing table 12. Here, since a B5 size document is placed on the document placement table 12, the afterglow from the document cover 11 in a corresponding portion is blocked by the document. Therefore, as shown in FIG. 3, the shaded area does not include the area shielded by the original.

  The PSD 210 receives the afterglow from the document cover 11 in the shaded area, and outputs currents divided in a certain ratio corresponding to the X direction from the x1 terminal and the x2 terminal connected to the cathode electrode, respectively. Currents divided in a certain ratio corresponding to the Y direction are output from the y1 terminal and the y2 terminal connected to the anode electrode. These output currents are given to a control unit described later, and the size of the document placed on the document placement table 12 is determined by the control unit based on the output current value.

  Next, the operation of the document reading unit 3 when the document set in advance on the ADF 100 provided in the upper housing is automatically sent, particularly the document size detection operation using the fixed platen unit 110 will be described in detail.

  FIG. 4 is a schematic cross-sectional view of the image forming apparatus 1 showing the position of the exposure scanning unit 13 when a document set in advance on the ADF 100 is automatically sent. As shown in FIG. 4, the exposure scanning unit 13 reads an image of a document passing immediately below the fixed platen unit 110 in the main scanning direction, and therefore is directly below the fixed platen unit 110 (precisely, directly below the transmission unit 120). Move to.

  In addition to the fixed platen unit 110, the ADF 100 includes a document regulating plate 101, a drawing roller 102, a conveyance roller 103, a registration roller 104, a discharge roller 105, a document tray 108, and a document discharge tray 109. Prepare.

  The document regulating plate 101 is provided on a document tray 108 on which a plurality of documents Pm are stacked, and regulates the stacking position of the documents Pm so that the sides of the documents Pm are aligned. Here, a general conventional document restriction plate has a sensor for detecting the width of the document Pm (the length in the direction orthogonal to the feeding direction of the document Pm), for example, depending on the position of the document restriction plate 101. A known detection device including a variable resistor whose resistance value changes is provided. Further, a general conventional document tray is provided with a sensor for detecting the vertical width of the document Pm (the length of the document Pm in the feeding direction), for example, an optical sensor arranged at an appropriate position. However, the ADF 100 in the present embodiment includes a plurality of optical sensors for detecting the vertical width of the document Pm, in this case, a plurality of positions provided according to the size of the document placed on the document tray 108. Only the optical sensor is provided, and no dedicated sensor for detecting the width of the document Pm is provided. Therefore, the ADF 100 can be configured simply and inexpensively.

  When the operation of the ADF 100 is started, the calling roller 102 sequentially repeats the operation of taking only one uppermost document of the plurality of documents Pm until the operation of the ADF 100 is completed. The conveyance roller 103 sequentially conveys the original document taken in from the calling roller 102 to the registration roller 104. The registration roller 104 corrects the registration and skew of the document, and then sends the document at a predetermined timing so as to pass directly below the fixed platen unit 110 and directly above the transmission unit 120. The discharge roller 105 sequentially discharges the document sent from the registration roller 104 onto the document discharge tray 109. These rollers are rotationally driven by a drive motor (not shown) based on detection results of various sensors (not shown) and control by a control unit (not shown).

  The image of the document sent immediately below the fixed platen unit 110 in the sub-scanning direction is sequentially read in the main scanning direction at a predetermined timing by the exposure scanning unit 13 that has moved directly below the fixed platen unit 110. As a result, the entire document image is read.

  Here, the fixed platen unit 110 receives strong light from the light source 131 of the exposure scanning unit 13 in an area other than the area shielded by the document passing immediately below (hereinafter referred to as “light receiving area”). While is turned off, the light receiving region of the stationary platen unit 110 emits light (emits afterglow). Therefore, the exposure scanning unit 13 turns off the built-in light source 131 and performs a reading operation in the main scanning direction at a predetermined timing, in this case, immediately after the first original is passed. Then, the CCD of the exposure scanning unit 13 outputs a voltage signal including a voltage corresponding to the case where only the portion corresponding to the light receiving area is bright (white). Based on the output signal from the CCD, the control section It is possible to detect the width of Pm (the length along the main scanning direction).

  The exposure scanning unit 13 temporarily turns off the light source 131 while the first document is passing, and performs the reading operation in the main scanning direction in the off state, thereby detecting the width of the document Pm. Also good. Further, by temporarily turning off the light source 131 when the leading edge of the first document in the feeding direction partially shields the fixed platen unit 110 and performing a reading operation in the main scanning direction in the off state, The width of the document Pm may be detected.

  As described above, the document reading unit 3 reads the image of the document and detects the document size under the control of the control unit built in the image forming apparatus 1. Hereinafter, the operation of the image forming apparatus 1 controlled by the control unit will be described in detail.

<3. Operation of image forming apparatus>
The operation of the image forming apparatus 1 according to the present embodiment having the above-described configuration is controlled by a control unit 10 including a microcomputer including a CPU, a ROM, a RAM, various interfaces, and the like, and a control program thereof. FIG. 5 is a block diagram showing functions of the control unit. The control unit 10 includes components of the document reading unit 3, the document cover opening / closing sensor 150, the image forming unit 6, the sheet feeding unit 7, the sheet stacking unit 2, and the command input unit 90, such as a motor for driving a roller. It is connected to actuators, sensors such as detection switches, and operation panel units.

  FIG. 6 is a flowchart showing a processing flow of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 6, first, the control unit 10 of the image forming apparatus 1 accepts an input of an operator's print request to an operation panel (not shown) corresponding to the command input unit 90 from the standby state (step S10). . The input of the print request includes, for example, inputs such as the number of prints, necessity of stapling processing and offset processing. For convenience of explanation, it is assumed here that the document size is not input and the document size is automatically detected.

  In step S20, the control unit 10 refers to the detection result of the optical sensor for detecting the placement of the original Pm provided on the original tray 108 of the ADF 100 or the optical sensor for detecting the vertical width of the original Pm. Then, it is determined whether or not the document Pm is placed on the document tray 108 of the ADF 100. If the result of this determination is that a document Pm is placed on the document tray 108 (Yes in step S20), a subroutine process for image reading by the ADF 100 is performed (step S30), and the process proceeds to step S50. move on. As a result of the determination, if the document Pm is not placed (No in step S20), a subroutine process for reading an image of the document placed on the document placing table 12 is performed (step S20). S40), the process proceeds to step S50.

  In step S <b> 50, the control unit 10 causes the image forming unit 6 to form an image on the paper P supplied from the paper supply unit 7 based on the read image data of the original. That is, the image data of the document read in step S30 or step S40 is subjected to image processing and then sequentially stored in the memory of the control unit 10 or a dedicated memory (not shown), and after all the documents are read, Sequentially supplied from the memory to the LSU 22. Further, the paper feed unit 7 selects the paper P corresponding to the document size read in step S30 or step S40 based on the control of the control unit 10, and feeds the paper P to the LSU 22. The detailed operation of the image forming unit 6 including the LSU 22 has been described above.

  Subsequently, in step S60, the control unit 10 causes the paper stack unit 2 to eject the paper P to the stack tray 59 without causing the paper stack unit 2 to perform post-processing on the basis of the input content received in step S10. Note that the document size information may also be used in this post-processing. In that case, for example, paper that is not allowed to enter the paper stack unit 2 can be selected based on the control of the control unit 10, and the paper can be discharged to the main body tray 5. When the above processing is completed, the image forming apparatus 1 is in a standby state until the next print request input is accepted (step S10).

  Further, the contents of each subroutine process for image reading described above will be described in detail below. FIG. 7 is a flowchart showing a detailed flow of a subroutine process (step S30) for reading an image by the ADF 100.

  As shown in FIG. 7, the control unit 10 first moves the exposure scanning unit 13 directly below the fixed platen unit 110 (transmission unit 120) shown in FIG. 4 (step S31). Next, the control unit 10 receives the detection result of the optical sensor for detecting the vertical width of the document Pm provided on the document tray 108 (step S32). Based on the detection result, the control unit 10 acquires the vertical width of the document Pm.

  Subsequently, in step S33, the control unit 10 appropriately drives the drawing roller 102, the conveyance roller 103, the registration roller 104, and the discharge roller 105 to send the document Pm in the sub-scanning direction. Are sequentially read in the main scanning direction. As a result, the entire document image is read.

  Here, the control unit 10 determines whether or not the entire document image has been read (step S34), and if it is determined that the process has ended (Yes in step S34), the process proceeds to the next step S35 and ends. If it is not determined that the document has been read (No in step S34), the document is read until it is finished (S34 → S33 → S34).

  Thereafter, when the reading of the document image is completed, the control unit 10 turns off the light source 131 of the exposure scanning unit 13 and performs a reading operation in the main scanning direction (for the fixed platen unit 110 where afterglow occurs in the light receiving area). Thus, the width of the original Pm is detected (step S35). This configuration has been described above.

  In step S34, it is determined whether or not the first original has reached a predetermined position, for example, the leading end of the first original in the feeding direction has reached a position where the stationary platen 110 is partially shielded. May be. In this case, in order to increase the amount of afterglow in step S35, the light source 131 of the exposure scanning unit 13 is turned on for a predetermined time and then turned off to perform the reading operation, thereby detecting the width of the original Pm. May be.

  Subsequently, in step S36, the control unit 10 acquires the entire document image by sending the document Pm in the sub-scanning direction and causing the exposure scanning unit 13 to read in the main scanning direction in the same manner as in step S33.

  Here, the control unit 10 determines whether or not all of the image reading of the document Pm has been completed (step S37). If it is determined that the reading has been completed (Yes in step S37), this subroutine processing ends. Then, the process returns to the process shown in FIG. 6 and if it is determined that the process has not been completed (No in step S37), the document is read until the process is completed (S37 → S36 → S37). When reading of all the originals is completed, the original Pm is not placed on the original tray 108. Therefore, the control unit 10 detects the placement of the original Pm provided on the original tray 108 of the ADF 100. The above determination is performed with reference to the detection result of the optical sensor for detecting the vertical width of the original Pm or the optical sensor for detecting the vertical width of the document Pm.

  Subsequently, a subroutine process (step S40) for reading an image of the document placed on the document placement table 12 will be described in detail. FIG. 8 is a flowchart showing a detailed flow of a subroutine process for reading an image of a document placed on the document placement table 12.

  As shown in FIG. 8, the control unit 10 first moves the exposure scanning unit 13 to a standby position, for example, directly below the fixed platen unit 110 (transmission unit 120) shown in FIG. 4 (step S41). This is to prevent afterglow from the document cover 11 from being blocked by the exposure scanning unit 13 before reaching the document size detector 200.

  Subsequently, the control unit 10 acquires a detection result from the document cover opening / closing sensor 150 (step S42), and determines whether or not the upper housing is closed based on the detection result (step S43). If it is determined that it is closed (Yes in step S43), the process proceeds to the next step S44, and if it is not determined that it is not closed (No in step S43), the detection result is displayed until it is closed. Acquisition is repeated (S43 → S42 → S43). However, in practice, an error process such as outputting a warning to close the upper housing (including the document cover) and outputting an error display if the predetermined time has passed without being closed is performed. Is preferred.

  If it is determined that the upper housing is closed, in step S44, the control unit 10 places the document on the document table 12 based on the detection result from the document size detector 200 that receives the afterglow of the document cover 11. The size of the placed document is detected. That is, as described above, the PSD 210 of the document size detector 200 outputs currents divided in a certain ratio from the x1 and x2 terminals connected to the cathode electrode and the y1 and y2 terminals connected to the anode electrode, respectively. To do. The control unit 10 determines (detects) the document size corresponding to the above-described ratio of these output currents by referring to a table in advance indicating the correspondence between the ratio and the document size. By making a determination based on the ratio in this way, the amount of afterglow of the document cover 11 varies (uniformly) according to the installation environment of the apparatus, the time the document cover 11 has been opened, and the like. Even in the case of this embodiment, the determination can be made accurately. The above-described determination method referring to such a table is an example, and the determination may be made with reference to a predetermined calculation formula, a condition determination formula, or the like.

  Next, in step S <b> 45, the control unit 10 moves the exposure scanning unit 13 to a position (starting position shown in FIG. 1) at which reading of the document placed on the document placing table 12 is to be started.

  Subsequently, in step S46, the control unit 10 moves the exposure scanning unit 13 in the sub-scanning direction (Y direction) and transfers the image of the document placed at an appropriate timing to the exposure scanning unit 13 in the main scanning direction ( By scanning in the X direction, an image of the entire original image is acquired.

  Here, the control unit 10 determines whether or not the image reading of the document has ended (step S47). If it is determined that the reading has ended (Yes in step S47), the subroutine processing ends. Returning to the process shown in FIG. 6, if it is not determined that the process has been completed (No in step S47), the document is read until the process is completed (S47 → S46 → S47).

<4. Effect>
As described above, in the document reading unit 3 of the image forming apparatus 1 according to the above-described embodiment, the phosphorescent material is applied to the surfaces of the document cover 11 and the fixed platen unit 110, and the afterglow of this material is converted into the document size. By receiving the data by the detector 200, the document size is detected. With this configuration, since it is not necessary to install a light source for detecting the document size at an accurate position, a simple and low-cost configuration can be achieved, and detection is performed by applying a predetermined pattern to the document cover. Compared to the conventional example, the document size can be accurately detected.

  In particular, the document cover 11 generates afterglow by absorbing external light, and the fixed platen unit 110 generates afterglow by absorbing light for image reading (from the light source 131 of the exposure scanning unit 13). Therefore, it is not necessary to provide a new illumination device for detecting the document size, and it is possible to eliminate power consumption required by the light source for detecting the document size.

<5. Main modification>
In the above embodiment, the original cover 11 (the phosphorescent substance) is stored by external light, and the original size is detected by receiving the afterglow by the original size detector 200, and then the image is read. On the other hand, in the main modification of the present embodiment, the document size detector 200 is omitted, and the document size detection operation and the image reading operation are alternately performed. Hereinafter, the operation of the image forming apparatus 1 in this main modification will be described with reference to FIG.

  FIG. 9 is a flowchart showing a detailed flow of a subroutine process for reading an image of a document placed on the document placement table 12 in the main modification. This subroutine process is a process replacing the subroutine process shown in FIG. 8 with respect to the process of step S40 shown in FIG.

  As shown in FIG. 9, the control unit 10 acquires the detection result from the document cover opening / closing sensor 150 (step S401), and determines whether or not the upper housing is closed based on the detection result (step S402). ). If it is determined that it is closed (Yes in step S402), the process proceeds to the next step S403, and if it is determined that it is not closed (No in step S402), the detection result until it is closed. Is repeated (S402 → S401 → S402). Note that the error processing is preferably performed here, as in step S43 shown in FIG.

When it is determined that the upper housing is closed, the control unit 10 performs control to move the exposure scanning unit 13 once to a predetermined start position and then move it at a constant speed in the sub-scanning direction (Y direction). Start (step S403). Note that the exposure scanning unit 13 is generally moved at a constant speed after a predetermined time has elapsed from the start of movement, and rapid acceleration and deceleration are difficult particularly when the exposure scanning unit 13 is moved at a high speed. Therefore, control that moves at a constant speed in this way is preferable.

  When the exposure scanning unit 13 is in a constant speed movement state and reaches the document reading position, the control unit 10 moves the exposure scanning unit 13 in the sub-scanning direction (Y direction) at a constant speed, and then the light source of the exposure scanning unit 13. 131 is lit and the image of the placed document is read in the main scanning direction (X direction) by the exposure scanning unit 13 (step S404).

  Subsequently, the control unit 10 immediately turns off the light source 131 of the exposure scanning unit 13 while moving the exposure scanning unit 13 at a constant speed in the sub-scanning direction (Y direction). The image of the placed document is read in the main scanning direction (X direction) (step S405). When the original images on the line extending in the main scanning direction obtained at this time are sequentially connected in the sub-scanning direction, the original image on the original cover 11 that appears bright by the afterglow is darkened by being shielded by the original. An image including the area to be captured is obtained. Note that this image is stored in a memory area different from that of the original image in step S404.

  Here, the control unit 10 determines whether or not the image reading of the document has been completed (step S406). When it is determined that the document has ended, the control unit 10 proceeds to the subsequent step S407 and determines that it has not ended. The reading of the original is executed until the process is completed (S406 → S404 → S405 → S406).

  Next, the control unit 10 detects the size of the document by determining the size of a region that is included in the image obtained in step S405 and appears dark corresponding to the document (step S408). That is, the control unit 10 extracts a border line between light and dark with a differential filter or the like, and determines a document size corresponding to the shape and size by referring to a predetermined table or the like. Such image processing is well known, but in this embodiment, an image to be subjected to image processing (here, a dark image of a document) and a background image (here, a bright image of the document cover 11) are exposed. It is characterized in that it can be obtained only when the light source 131 of the scanning unit 13 is turned off. In this respect, since the document cover of the conventional image forming apparatus is white and does not have a phosphorescent material applied, the document and the document cover have the same color (whether the light source 131 of the exposure scanning unit 13 is turned off or on). In other words, it is almost white when turned on and almost black when turned off), so that the boundary line between the document and the document cover cannot be easily identified, and it is extremely difficult to extract this boundary line by the above image processing. As described above, in the present embodiment, when acquiring a document image for image formation, the document and the document cover are made the same color (so that an undesirable boundary line cannot be seen) and only when the document size is determined. The boundary line can be seen.

  Thereafter, the subroutine processing ends, and the processing returns to the processing shown in FIG. In addition, since the process of the said step S404 and step S405 is performed in a very short time, it is preferable that the light source 131 of the exposure scanning unit 13 can repeat blinking continuously and for a short time, such as an LED light source. In the main modification, the light source 131 is turned on and off alternately every time an image is acquired in the main scanning direction. However, the image acquisition process in the main scanning direction when the light source 131 is turned on. After (S405) is performed a plurality of times, the image acquisition process (S406) in the main scanning direction with the light source 131 turned off may be performed once. In this configuration, it is necessary to stop or decelerate the exposure scanning unit 13 when acquiring an image in the main scanning direction with the light source 131 turned off (S406), which is suitable for an image reading unit having a relatively low reading speed. It is.

<6. Other modifications>
In the above embodiment, Luminova (registered trademark), which is a phosphor having a high luminance and long afterglow, is used as the phosphorescent material applied to the document cover 11, but instead, the afterglow time (the phosphorescence is stopped). When a phosphorescent material having a very short time after the occurrence of afterglow is used, the afterglow detection by the document size detector 200 may not be sufficiently performed. The same applies to the case where the apparatus is placed in an environment where there is no external light itself or in a weak environment.

  Therefore, a new light source is provided to illuminate the document cover 11 and this light source is used, or the light source 131 of the exposure scanning unit 13 is used. That is, by using these light sources after the upper housing is closed, the original cover 11 (the phosphorescent substance) is made to store light, and immediately after that, the original size detector 200 detects the afterglow. Thus, the document size can be detected by the document size detector 200 even when the afterglow time is short or the amount of afterglow is small. The light source is turned on after placing the document on the document placing table 12, so that no light is stored in a portion shielded by the document. Therefore, particularly when the original is a thin material, the portion of the original cover 11 that is shielded by the original becomes darker than the case where the entire original cover 11 is stored as in the above-described embodiment. Since the contrast becomes higher, the detection accuracy can be increased. This effect is the same in the main modification. A series of operations from lighting to detection may be performed in step S44 shown in FIG.

  Further, in this configuration, unlike the case of light storage by external light that is not always stable, the amount of afterglow in the document cover 11 (the light storage material) is controlled by accurately controlling the light amount and lighting time of the light source. be able to. Therefore, the light receiving area in the document cover 11 can be calculated (by the control unit 10) by accurately detecting the amount of light received by the document size detector 200. Therefore, an element whose voltage or current is changed according to received light, for example, an element having a photovoltaic effect such as a photodiode or a phototransistor, an element having a photoconductive effect such as a CdS cell or a PbS cell, and a photoelectron A document size can be detected by using an element having a photoelectron emission effect such as a multiplier tube in the document size detector 200 that functions as a light detection means. However, when the document size is determined based on the area as described above, it is impossible to distinguish between the case where the document is placed vertically and the case where the document is placed horizontally. Thus, two elements are provided so as to receive afterglow from different portions of the document cover 11. You may comprise. In addition, a configuration in which a phosphorescent substance is applied to the document cover 11 in a predetermined pattern so that a light-shielded region (and its area) is changed between the portrait orientation and the landscape orientation is also conceivable.

  Further, a plurality of positions are determined such that the afterglow from the document cover 11 is received or blocked by the document (referred to as “light reception state”) is a different combination for each document size. A photodetector is provided at the designated position. The control unit 10 may detect the document size corresponding to the combination based on each light reception state of the photodetector by referring to a predetermined table or the like.

  In the above embodiment, a plurality of optical sensors provided at positions corresponding to the size of the document placed on the document tray 108 are illustrated as sensors for detecting the vertical width of the document Pm. The sensor is not limited to this, and any sensor having a known configuration that can detect the length of the document Pm in the feeding direction may be used. For example, the length information of the document Pm is calculated based on the time when a pre-registration detection switch (not shown) provided in front of the registration roller 104 is turned on when the document Pm is conveyed, and the length of the document Pm is calculated from the calculated value. The width may be detected.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view schematically showing the vicinity of a document reading unit in the image forming apparatus in a state where an upper housing is opened in the embodiment. It is the schematic diagram which looked at PSD in the said embodiment from the perpendicular direction upper direction with respect to the document mounting base. It is a schematic sectional view of the image forming apparatus showing the position of the exposure scanning unit when a document set in advance in the ADF in the embodiment is automatically fed. It is a block diagram which shows the function of the control part in the said embodiment. 4 is a flowchart illustrating a processing flow of the image forming apparatus according to the embodiment. It is a flowchart which shows the detailed flow of the subroutine process for the image reading by ADF in the said embodiment. It is a flowchart which shows the detailed flow of the subroutine process for the image reading of the original document mounted on the original document mounting base in the said embodiment. It is a flowchart which shows the detailed flow of the subroutine process for the image reading of the original document mounted on the original document mounting base in the main modification of the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Paper stack part 3 ... Document reading part 5 ... Main body tray 6 ... Image forming part 7 ... Paper feed part 11 ... Document cover 12 ... Document mounting stand 13 ... Exposure scanning unit 14 ... Reflector 16 ... Photoelectric Conversion element (CCD)
17 ... Photoconductor 18 ... Developing device 22 ... Laser scanning unit (LSU)
31 ... Paper cassette 44 ... Fixing device 59 ... Stack tray (discharge tray)
100: Automatic document feeder (ADF)
DESCRIPTION OF SYMBOLS 101 ... Document control board 105 ... Discharge roller 108 ... Document tray 109 ... Document discharge tray 110 ... Fixed platen part 120 ... Transmission part 130 ... (Exposure light source) 150 ... Document cover open / close sensor 200 ... Document size detector P ... Paper Pm ... Original X ... Main scanning direction Y ... Sub-scanning direction

Claims (5)

An image reading apparatus capable of detecting the size of a document to be read,
A reading unit that includes a predetermined light source and optically reads an image of the document;
A background unit disposed in the vicinity of the surface opposite to the document surface to be read by the reading unit, and a phosphorescent material disposed on the surface of the document;
Control means for detecting the size of the document based on the light emitted from the phosphorescent material of the background means ,
The background means absorbs light energy from the light source;
The reading unit alternately repeats an operation of reading the image of the document halfway after turning on the light source and an operation of receiving light emitted from the phosphorescent material of the background unit after turning off the light source, Scan the original image,
The control unit, based on the light from the light-storing material received by said reading means, an image reading apparatus which is characterized that you detect the size of the document. The image reading apparatus according to claim 1 , wherein the background unit absorbs light from the light source partially blocked by the document. The image reading apparatus according to claim 1 , wherein the predetermined light source is a light source for reading an image of the document by the reading unit. The reading unit includes an exposure scanning unit that reads an image of the document in a predetermined main scanning direction or receives light from the phosphorescent material, and moves the exposure scanning unit at a constant speed in a predetermined sub-scanning direction. 4. The image reading apparatus according to claim 1, wherein an operation of reading an image of the original and an operation of receiving light from the phosphorescent substance are alternately repeated. 5. An image reading apparatus according to any one of claims 1 to 4 ,
An image forming apparatus comprising: an image forming unit configured to form an image on a predetermined medium corresponding to a size of the original detected by the image reading apparatus based on an image of the original read by the image reading apparatus.

Images