JP2014064168A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reliably determining the size of a document with a white background, even when the document is placed on platen glass without largely opening a platen cover.SOLUTION: An image forming apparatus includes: a first open/close detection sensor 35 that detects opening of a document feeding unit 3 covering platen glass; a second open/close detection sensor 26 that detects opening of the document feeding unit 3 at a pre-set threshold angle; and a document size determination unit 71 that, when the opening of the document feeding unit 3 at the threshold angle is not detected and the open and close of the document feeding unit 3 is detected, acquires third determination data by front side position determination scan in which a scanner 21 scans LED arrays on the depth side in a main scanning direction that are only partially turned on, acquires forth determination data by determination scan in which the scanner 21 scans the plurality of LED arrays 241a to 241k on the front side in the main scanning direction that are only partially turned on, and determines the size of the document in the main scanning direction on the basis of the third determination data and the fourth determination data.

Description

  The present invention relates to an image forming apparatus including an original reading unit that reads an original placed on a platen glass, and more particularly to an image forming apparatus having an original size determination function.

  2. Description of the Related Art Conventionally, an electronic copying machine, a facsimile, and the like are known as an image forming apparatus provided with a document reading device that reads a document such as a photograph or document on a platen glass. In such an image forming apparatus, there is known an apparatus that first determines a document size of a document placed on a platen glass, and controls reading, selection of a sheet to be printed, and the like based on the determined document size. .

  As a method for detecting a document size, it has been proposed to use image data read by a scanner that reads a document (see, for example, Patent Document 1). In Patent Document 1, an opening / closing detection means for detecting opening / closing of the platen cover in two stages is provided. When it is detected that the platen cover is about to be closed, the first scanning is performed and the platen cover is completely closed. If detected, the second scan is performed, and the document size is determined based on the line sensor output obtained by these two scans.

JP-A-11-75025

  In the prior art of Patent Document 1, the first scanning performed when the platen cover is about to be closed needs to be performed in a state where the light emitted from the light source is not focused on the light receiving unit in a range other than the document MS. . However, when a document is placed on the platen glass without opening the platen cover greatly, it may not be detected that the platen cover is being closed and the first scan may not be performed. . Alternatively, even if the first scanning is performed, the light emitted from the light source is imaged on the light receiving unit by the reflection of the platen cover. In this case, there is a problem that there is no difference between the first scan and the second scan, and the size of the document with a white background cannot be determined.

  In view of the above problems, the object of the present invention is to solve the problems of the prior art, and even when the original is placed on the platen glass without opening the platen cover greatly, the size of the original whose background is white It is an object of the present invention to provide an image forming apparatus that can reliably determine the image quality.

The image forming apparatus of the present invention scans a document placed on a platen glass while moving a scanner in which a plurality of LEDs are arranged as a light source in the main scanning direction in the sub scanning direction, and reads the image data. A first opening / closing detecting means for detecting the opening of a platen cover covering the platen glass; a second opening / closing detecting means for detecting opening of the platen cover at a preset threshold angle; When the opening / closing of the platen cover is detected by the first opening / closing detection means without detecting the opening at the threshold angle by the two opening / closing detection means, the scanner scans the back side of the plurality of LEDs in the main scanning direction. The front side position determination data is obtained by the front side position determination scan in which only a part of the LED is lit, and the main scanning of the plurality of LEDs is performed. The back side position determination data is acquired by the back side position determination scanning in which only a part of the front side is lit, and the main scanning direction is determined based on the acquired near side position determination data and the back side position determination data. And an original size determining means for determining an original size.
Further, in the image forming apparatus according to the present invention, in the near side position determination scanning, the LED in a range narrower than the minimum width of the assumed document size is turned on from the back side in the main scanning direction, and the back side position determination is performed. In the main scanning, the LED in a range narrower than the minimum width of the assumed document size may be turned on from the front side in the main scanning direction.
Further, in the image forming apparatus according to the present invention, the document size determination means may be a range that exceeds the assumed maximum length of the document in the sub-scanning direction from a sub-scanning direction reference line for aligning the document in the sub-scanning direction The near-side position determination data or the back-side position determination data is acquired by the near-side position determination scan or the back-side position determination scan, and the document size in the sub-scanning direction based on the acquired determination data May be determined.

  According to the present invention, even when a document is placed on the platen glass without opening the platen cover greatly, the determination scanning in which only a part of the plurality of LEDs on the back side in the main scanning direction is turned on. The determination data is acquired by the above, and the determination data is acquired by the determination scanning in which only a part of the plurality of LEDs on the front side in the main scanning direction is turned on. Based on the acquired determination data, the document size in the main scanning direction is acquired. By determining the above, it is possible to reliably determine the size of the document whose white background is white.

1 is an external perspective view showing a configuration of an embodiment of an image forming apparatus according to the present invention. 1 is an external perspective view showing a configuration of an embodiment of an image forming apparatus according to the present invention. 1 is a schematic cross-sectional view showing an internal configuration of an embodiment of an image forming apparatus according to the present invention. It is an external appearance perspective view which shows the structure of the light source shown in FIG. FIG. 3 is a block diagram showing a schematic configuration of the copying machine shown in FIGS. 1 and 2. 5 is a flowchart for explaining a document size determination operation in the embodiment of the image forming apparatus according to the present invention. FIG. 6 is an explanatory diagram for explaining a document size determination operation based on first determination data and second determination data in the embodiment of the image forming apparatus according to the present invention. It is a figure which shows the lighting state of the light source at the time of acquiring 3rd determination data and 4th determination data in embodiment of the image forming apparatus which concerns on this invention. FIG. 10 is an explanatory diagram for explaining a document size determination operation based on third determination data, fourth determination data, and second determination data in the embodiment of the image forming apparatus according to the present invention. FIG. 10 is an explanatory diagram for explaining a document size determination operation based on third determination data, fourth determination data, and second determination data in the embodiment of the image forming apparatus according to the present invention.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
The image forming apparatus according to the present embodiment is a copying machine 1, and includes a document reading unit 2, a document feeding unit 3, a main body unit 4, and an operation unit 5 with reference to FIGS. 1 and 2. Yes. The document reading unit 2 is disposed on the top of the main body unit 4, and the document feeding unit 3 is disposed on the top of the document reading unit 2. The operation unit 5 is disposed on the front side of the copying machine 1. The document feeding unit 3 and the document reading unit 2 are connected to each other by a hinge mechanism 36 on the back side of the copying machine 1, and the document reading unit 2 is opened by opening the document feeding unit 3 upward from the front side. The platen glass 22 on the upper surface can be opened. FIG. 1 shows a state where the document feeding unit 3 is opened widely, and FIG. 2 shows a state where the document feeding unit 3 is opened small. Although the image forming apparatus of the present embodiment has been described with respect to the copying machine 1, it is needless to say that a scanner, a multifunction machine, and the like are included.

  On the front side of the copying machine 1, an operation unit 5 for setting and operating instructions of the copying machine 1 is disposed. The operation unit 5 is provided with a liquid crystal display unit 51 and operation buttons 52. The user operates the operation unit 5 and inputs an instruction to perform various settings of the copying machine 1 and execute various functions such as image formation. The liquid crystal display unit 51 displays the status of the copier 1, displays the image formation status and the number of copies, and can be used as a touch panel for various settings such as functions such as double-sided printing and black-and-white reversal, magnification setting, and density setting. It has become. The operation buttons 52 are a start button for instructing the user to start image formation, a stop / clear button used when the image formation is stopped, and other settings for the copying machine 1 to default. A reset button, a numeric keypad, and the like are provided.

  As shown in FIG. 3, the document reading unit 2 includes a scanner 21, a platen glass 22, and a document reading slit 23. The scanner 21 includes a light source 24 using an LED (Light Emitting Diode) and a light receiving unit 25 including a CCD (Charge Coupled Device) line sensor, a CMOS (Complementary Metal Oxide Semiconductor) line sensor, and the like. The unit 3 is configured to be movable in the document conveyance direction. Referring to FIG. 4, the light source 24 includes a plurality of LED arrays 241a to 241k arranged in the main scanning direction from the back side to the front side, and drive circuits 242a to 242k for driving the LED arrays 241a to 241k, respectively. Has been. The LED arrays 241a to 241k are elements in which a plurality of LEDs are arranged one-dimensionally. The platen glass 22 is a platen made of a rectangular transparent member such as glass and disposed on the upper surface of the document reading unit 2. As shown in FIG. 1, the setting position of the document MS on the platen glass 22 in the present embodiment is a side located on the left side toward the back side of the platen glass 22 (hereinafter referred to as a sub-scanning direction reference line B). And a center line in the main scanning direction on the platen glass 22 (referred to as a main scanning direction reference line C). In the present embodiment, the center line of the document MS and the main scanning direction reference line C do not necessarily coincide with each other, and when the document MS is set, it can be seen from either the back side or the near side of the platen glass. As long as it is in a distant state. The document reading slit 23 is a slit formed in a direction orthogonal to the document transport direction by the document feeder 3.

  The document feeding unit 3 includes a document placement unit 31, a document discharge unit 32, and a document transport mechanism 33. The originals placed on the original placement unit 31 are sequentially fed out one by one by the original conveyance mechanism 33, conveyed to a position facing the original reading slit 23, and then discharged to the original discharge unit 32.

  The document feeding unit 3 functions as a platen cover that opens and closes the upper surface of the platen glass 22. By opening the document feeding unit 3 upward, the upper surface of the platen glass 22 is opened and a document can be set on the platen glass 22. Become. Further, a surface facing the platen glass 22 in the document feeding unit 3 is a white document pressing surface 34. Referring to FIG. 1, a second opening / closing detection sensor 26 is provided in the document reading unit 2, and a first opening / closing detection sensor 35 is provided in the document feeding unit 3 to detect opening / closing of the document feeding unit 3 (platen cover). Each is provided as detection means. The first open / close detection sensor 35 is a micro switch that detects the opening of the document feeding unit 3 (platen cover). The first opening / closing detection sensor 35 is turned on when the document feeding unit 3 (platen cover) is closed, and the document feeding unit 3 ( The platen cover is turned off in the open state. The second open / close detection sensor 26 is a micro switch that detects that the opening of the document feeding unit 3 (platen cover) exceeds a preset threshold angle, and the opening angle of the document feeding unit 3 (platen cover). Is turned on below the threshold angle, and turned off when the opening angle of the document feeder 3 (platen cover) exceeds the threshold angle. The threshold angle at which the second open / close detection sensor 26 is turned on / off is set as follows. That is, when image data is read by the document reading unit 2 with the document feeding unit 3 (platen cover) opened at the threshold angle, the light emitted from the light source 24 is received outside the document MS. The threshold angle is set so that no image is formed on the portion 25.

  When reading of a document is instructed by the operation button 52 of the operation unit 5 in a state where no document is placed on the document placement unit 31 or in an opened state where the document feeding unit 3 (platen cover) is opened, the platen A document placed on the glass 22 is read. When reading a document placed on the platen glass 22, the scanner 21 is moved to a position facing the platen glass 22, and the document placed on the platen glass 22 is moved in the sub-scanning direction orthogonal to the main scanning direction. Reading is performed while scanning from the reference line B in the sub-scanning direction to acquire image data, and the acquired image data is output to the main body unit 4.

  When reading of a document is instructed by the operation button 52 of the operation unit 5 in a state where the document is placed on the document placing unit 31, the document conveyed by the document feeding unit 3 is read. When reading the document conveyed by the document feeding unit 3, the scanner 21 is moved to a position facing the document reading slit 23, and the document feeding operation by the document feeding unit 3 is performed via the document reading slit 23. The document is read synchronously to acquire image data, and the acquired image data is output to the main unit 4.

  The main body 4 includes a recording unit 6, and includes a paper feed unit 41, a paper feed roller 42, a paper transport path 43, a transport roller 44, and a discharge roller 45. The paper feed unit 41 is a paper feed cassette that stores a plurality of recording papers P. The paper feed roller 42 feeds the recording paper P from the paper feed unit 41 to the paper transport path 43 one by one. The recording paper P fed to the paper transport path 43 by the paper feed roller 42 is transported to the recording unit 6 by the transport roller 44. The recording paper P on which recording has been performed by the recording unit 6 is discharged by a discharge roller 45 into a discharge space 46 formed between the document reading unit 2 and the main body unit 4. As described above, the paper feed roller 42, the transport roller 44, and the discharge roller 45 function as a transport unit for the recording paper P.

  The recording unit 6 includes a photosensitive drum 61, a charging unit 62, an exposure unit 63, an image forming unit 64, a transfer unit 65, a fixing unit 66, and a cleaning unit 67. The exposure unit 63 is an optical unit including a laser device, a mirror, and the like. The exposure unit 63 outputs a laser beam based on image data to the photosensitive drum 61 uniformly charged by the charging unit 62 and exposes the photosensitive drum 61. An electrostatic latent image is formed on the surface of the drum 61. The image forming unit 64 is a developing unit that develops the electrostatic latent image formed on the photosensitive drum 61 using toner, and forms a toner image based on the electrostatic latent image on the photosensitive drum 61. The transfer unit 65 transfers the toner image formed on the photosensitive drum 61 by the image forming unit 64 to the recording paper P. The fixing unit 66 heats the recording paper on which the toner image is transferred by the transfer unit 65 to fix the toner image on the recording paper. The toner remaining on the photosensitive drum 61 is removed by the cleaning unit 67.

  FIG. 5 is a block diagram showing a schematic configuration of the copying machine 1. The document reading unit 2, document feeding unit 3, transport unit (feed roller 42, transport roller 44, discharge roller 45), operation unit 5 and recording unit 6 are connected to the control unit 7. Operation controlled. In addition, an image processing unit 8 and a storage unit 9 are connected to the control unit 7.

The control unit 7 is an information processing unit such as a microcomputer including a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for controlling the operation of the copying machine 1. The control unit 7 reads out a control program stored in the ROM and develops the control program in the RAM, thereby controlling the entire apparatus according to predetermined instruction information input from the operation unit 5. Further, the control unit 7 causes the document reading unit 2 to acquire a plurality of determination data according to the on / off states of the second opening / closing detection sensor 26 and the first opening / closing detection sensor 35, and the plurality of determination data. Functions as a document size determination unit 71 for determining the size of the document MS based on the above. The determination data is acquired by a width determination scan or a length determination scan by the document reading unit 2. The width determination scan by the document reading unit 2 is a scan for acquiring determination data for determining the size of the document MS in the main scanning direction. One to a plurality of lines from the sub-scanning direction reference line B in the sub-scanning direction. Get image data for minutes. Therefore, the image data for one to a plurality of lines from the sub-scanning direction reference line B in the sub-scanning direction becomes the determination data. The length determination scan by the document reading unit 2 is a scan for obtaining determination data for determining the size of the document MS in the sub-scanning direction, and the document is scanned from the sub-scanning direction reference line B in the sub-scanning direction. Image data in a range exceeding the assumed maximum length L _MAX of the MS is acquired. Accordingly, image data in a range exceeding the maximum length L _MAX in the sub-scanning direction from the sub-scanning direction reference line B becomes the determination data.

  The image processing unit 8 is a unit that performs predetermined image processing on the image data. For example, image improvement processing such as enlargement / reduction processing, gradation adjustment, and density adjustment is performed.

  The storage unit 9 is a storage unit such as a semiconductor memory or an HDD (Hard Disk Drive). The storage unit 9 stores image data acquired by reading a document by the document reading unit 2, and stores various management information. Yes.

Next, the document size determination operation in the copying machine 1 of the present embodiment will be described in detail with reference to FIGS.
In order to detect a series of operations (step S1) by an operator who opens the document feeding unit 3 (platen cover) and sets the document MS on the platen glass 22, the control unit 7 functions as a document size determination unit 71. The first opening / closing detection sensor 35 is turned off, that is, the opening of the document feeder 3 (platen cover) is monitored (step S2).

  When the second opening / closing detection sensor 26 is turned off in step S2, that is, when the opening of the document feeding unit 3 (platen cover) is detected, the document size determination unit 71 turns off the second opening / closing detection sensor 26, that is, document feeding. The opening exceeding the threshold angle of the section 3 (platen cover) (step S3) and the first opening / closing detection sensor 35 being turned on, that is, the closing of the document feeding section 3 (platen cover) are monitored (step S4).

  When the second opening / closing detection sensor 26 is turned off in step S3, that is, when the opening exceeding the threshold angle of the document feeding unit 3 (platen cover) is detected, the document size determination unit 71 turns on the second opening / closing detection sensor 26, That is, it is monitored whether or not the opening of the document feeder 3 (platen cover) is less than the threshold angle (step S5). This step S5 detects the timing at which the document feeder 3 (platen cover) is closed after the document MS is set in a state where the document feeder 3 (platen cover) is opened larger than the threshold angle. be able to.

  When it is detected in step S5 that the second open / close detection sensor 26 is turned off, that is, the opening of the document feeding unit 3 (platen cover) has become equal to or smaller than the threshold angle, the document size determination unit 71 causes the document reading unit 2 to The width determination scan is executed to acquire the first determination data (step S6). In step S6, the document reading unit 2 performs a width determination scan with the document feeding unit 3 (platen cover) opened at the threshold angle, and first determination data as shown in FIG. 7 is acquired. The In FIG. 7, the horizontal axis represents the main scanning direction, and the vertical axis represents the detection signal (luminance) from the light receiving unit 25. In addition, the detection signal by the light receiving unit 25 becomes higher as it is brighter (white), and becomes lower as it is darker (black).

  Next, the document size determination unit 71 monitors whether the first opening / closing detection sensor 35 is turned on, that is, whether the document feeding unit 3 (platen cover) is closed (step S7). When it is detected in step S7 that the first open / close detection sensor 35 is turned on, that is, the closing of the document feeding unit 3 (platen cover) is detected, the document size determination unit 71 causes the document reading unit 2 to perform a width determination scan. The second determination data is acquired (step S8). In step S8, the document reading unit 2 performs width determination scanning with the document feeding unit 3 (platen cover) closed, and second determination data as shown in FIG. 7 is acquired. FIG. 7A shows the first determination data and the second determination data when the background of the document MS is white, and FIG. 7B shows the first determination data when the background of the document MS is black. Determination data and second determination data are shown. In FIGS. 7A and 7B, the document pressing surface 34 is white.

Next, the document size determination unit 71 determines the size of the document MS in the main scanning direction based on the first determination data acquired in step S6 and the second determination data acquired in step S8 ( Step S9). The document size determination unit 71 determines the size of the document MS in the main scanning direction by comparing the first determination data and the second determination data with a preset threshold value S. That is, when the background of the document MS is white, the detection signal from the light receiving unit 25 appears as a large difference between the document MS and other regions in the first determination data shown in FIG. Therefore, by setting an appropriate threshold value S, a portion that is equal to or larger than the threshold value S is determined as the size of the document MS in the main scanning direction based on the first determination data. When the background of the document MS is black, the detection signal from the light receiving unit 25 appears as a large difference between the document MS and the other area in the second determination data shown in FIG. 7B. . Therefore, by setting an appropriate threshold value S, a portion less than the threshold value S is determined as the size of the document MS in the main scanning direction based on the second determination data. Note that the background of the document MS can be determined by comparing the detection signal with the threshold S within the minimum width W _MIN of the assumed document size in the main scanning direction.

  In step S3, the second opening / closing detection sensor 26 is turned off, that is, the first opening / closing detection sensor 35 is turned on in step S4, that is, the document is fed without detecting the opening exceeding the threshold angle of the document feeding unit 3 (platen cover). When the closing of the feeding unit 3 (platen cover) is detected, the document size determination unit 71 causes the document reading unit 2 to perform a width determination scan to acquire third determination data (step S10). Fourth determination data is acquired (step S11). Further, the second determination data is acquired by the same operation as step S8 (step S12). FIG. 9 shows the third determination data, the fourth determination data, and the second determination data when the background of the document MS is white. FIG. 10 shows the third determination data when the background of the document MS is black. The determination data, the fourth determination data, and the second determination data are shown. In both cases of FIGS. 9 and 10, the document pressing surface 34 is white.

Unlike the width determination scans in steps S6, S8, and S11, the width determination scan by the document reading unit 2 that acquires the third determination data in step S10 determines the position of the front side of the document MS. This is a front side position determination scan. Specifically, as shown in FIG. 8A, only a part of the back side of the plurality of LED arrays 241a to 241k is turned on to perform the front-side position determination scan. In the example shown in FIG. 8A, the width determination scan is performed while the LED arrays 241a to 241c are turned on and the other LED arrays 241d to 241k are turned off. As a result, a shadow on the near side of the document MS is generated on the document pressing surface 34. Therefore, in the third determination data acquired in step S10, as shown in FIG. 9, the detection signal of the shadow portion generated on the document pressing surface 34 is low. Note that the lighting range of the plurality of LED arrays 241a to 241k in the near side position determination scan is set to a range narrower than the minimum width W _{MIN of the} document size from the side located on the back side of the platen glass 22. This ensures that a shadow is generated at the position of the front side of the document MS.

Unlike the width determination scans in steps S6, S8, and S11, the width determination scan by the document reading unit 2 that acquires the fourth determination data in step S11 determines the position of the back side of the document MS. This is a back side position determination scan. Specifically, as shown in FIG. 8B, only the part on the near side of the plurality of LED arrays 241a to 241k is turned on to perform the back side position determination scanning. In the example shown in FIG. 8B, the width determination scan is performed in a state where the LED arrays 241i to 241k are turned on and the other LED arrays 241a to 241h are turned off. As a result, a shadow on the back side of the document MS is generated on the document pressing surface 34. Therefore, in the fourth determination data acquired in step S11, as shown in FIG. 10, the detection signal of the shadow portion generated on the document pressing surface 34 is low. The lighting range of the plurality of LED arrays 241a to 241k in the back side position determination scan is set to a range narrower than the minimum width W _{MIN of the} document size from the side located on the near side of the platen glass 22. This ensures that a shadow is generated at the position of the back side of the document MS.

  Next, the document size determination unit 71 is based on the third determination data acquired in step S10, the fourth determination data acquired in step S11, and the second determination data acquired in step S12. Then, the size of the document MS in the main scanning direction is determined (step S13). The document size determination unit 71 determines the size of the document MS in the main scanning direction by comparing the third determination data, the fourth determination data, and the second determination data with a preset threshold value S. That is, when the background of the document MS is white, as shown in FIG. 9, in the third determination data, the document MS and the document pressing surface 34 and the shadows on the near side of the document MS generated on the document pressing surface 34 are displayed. The detection signal from the light receiving unit 25 appears as a large difference between the position of the document MS and the document MS and the document pressing surface 34 in the fourth determination data, and the shadow of the back side of the document MS generated on the document pressing surface 34. The detection signal from the light receiving unit 25 appears as a large difference between the two points. Therefore, based on the third determination data and the fourth determination data, an appropriate threshold value S is set and a shadow portion generated on the document pressing surface 34 is detected, so that the front and back sides of the document MS are detected. Each position is detected, and the width from the position of the near side and the back side of the document MS to the position of the back side of the document MS is determined as the size of the document MS in the main scanning direction. When the background of the document MS is black, the detection signal from the light receiving unit 25 appears as a large difference between the document MS and other areas in the second determination data shown in FIG. Therefore, by setting an appropriate threshold value S, a portion less than the threshold value S is determined as the size of the document MS in the main scanning direction based on the second determination data. The background of the document MS is determined by comparing a threshold value S with a detection signal in a location where the document MS is reliably placed, for example, in the vicinity of the main scanning direction reference line C in the vicinity of the sub scanning direction reference line B. It is possible.

  After determining the size of the document MS in the main scanning direction in step S9 or step S13, the document size determination unit 71 detects and determines the size of the document MS in the sub-scanning direction (step S14), and ends the document size determination operation. To do. The document size determination unit 71 causes the document reading unit 2 to perform a length / width determination scan to acquire determination data for length determination, and based on the acquired determination data for length determination, the sub-scanning direction The size of the original MS is determined. Similar to the above-described size determination in the main scanning direction, the size determination in the sub-scanning direction is performed based on the difference between detection signals of the document MS, the document pressing surface 34, and the shadow generated on the document pressing surface 34. Therefore, when the background of the document MS is white and the size determination in the main scanning direction is performed based on the first determination data or the third determination data, the plurality of LED arrays 241a to 241a to 241 are performed in the same manner as in steps S10 and S11. Only a part of 241k is turned on, and the scan for length / width determination is executed. In this case, only a part on the back side may be used as in step S10, or only a part on the near side may be used as in step S11. As a result, it is possible to detect the boundary between the document MS and the shadow (the near side or the back side of the document MS) generated on the document pressing surface 34 in the obtained determination data for length determination. The size of the document MS in the scanning direction is determined. On the other hand, when the background of the document MS is black and the size determination in the main scanning direction is performed based on the second determination data, all the LED arrays 241a to 241k are turned on as in steps S6, S8, and S11. The length / width determination scan is executed. Thereby, in the obtained determination data for length determination, the boundary between the document MS and the document pressing surface 34 can be detected, and the size of the document MS in the sub-scanning direction is determined.

  As described above, in the present embodiment, the first open / close detection sensor 35 that detects the opening of the document feeding unit 3 (platen cover) that covers the platen glass 22 and the document feeding unit 3 (platen cover) in advance. The second opening / closing detection sensor 26 that detects opening at the set threshold angle, and the opening / closing at the threshold angle is not detected by the second opening / closing detection sensor 26, and the document feeding unit 3 is detected by the first opening / closing detection sensor 35. When the opening / closing of the (platen cover) is detected, the scanner 21 detects the third determination data by the front-side position determination scanning in which only a part of the plurality of LED arrays 241a to 241k on the back side in the main scanning direction is lit. And the front side position determination scan in which only a part of the front side in the main scanning direction of the plurality of LED arrays 241a to 241k is lit. To obtain a fourth judgment data, and is configured to determine the document size in the main scanning direction based on the third determination data and a fourth judgment data obtained. With this configuration, in the third determination data, the detection signal of the shadow portion on the near side of the document MS is low. In the fourth determination data, the detection signal of the shadow portion on the back side of the document MS is low. Accordingly, even when the document MS is placed on the platen glass 22 without opening the document feeder 3 (platen cover) large (beyond the threshold angle), the third determination data and the fourth determination data Based on the determination data, an appropriate threshold value S is set to detect a shadow portion generated on the document pressing surface 34, so that the size of the document MS having a white background in the main scanning direction can be reliably determined. Play.

  Further, in the present embodiment, in the near-side position determination scan for acquiring the third determination data, the LED arrays 241a to 241c in a range narrower than the minimum width of the assumed document size from the back side in the main scanning direction. Is turned on and the LED arrays 241a to 241c in a range narrower than the minimum width of the assumed document size are turned on from the near side in the main scanning direction in the back side position determination scanning for acquiring the fourth determination data. It is configured. With this configuration, it is possible to reliably cause shadows at the positions of the near side and the far side of the document MS.

Furthermore, in the present embodiment, the determination data for length determination in the range exceeding the maximum length L _MAX in the sub scanning direction from the sub scanning direction reference line B is acquired, and the acquired determination data for length determination The document size in the sub-scanning direction is determined based on the above. With this configuration, even when the document MS is placed on the platen glass 22 without opening the document feeder 3 (platen cover) large (beyond the threshold angle), the background of the document MS having a white background is displayed. There is an effect that the size in the sub-scanning direction can be reliably determined.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

DESCRIPTION OF SYMBOLS 1 Copier 2 Original reading part 3 Original feeding part 4 Main body part 5 Operation part 6 Recording part 7 Control part 8 Image processing part 9 Storage part
DESCRIPTION OF SYMBOLS 21 Scanner 22 Platen glass 23 Original reading slit 24 Light source 241a-241k LED array 242a-242k Drive circuit 25 Light-receiving part 26 2nd opening-and-closing detection sensor 31 Original mounting part 32 Original discharge part 33 Original conveyance mechanism 34 Original pressing surface 35 First Open / close detection sensor 36 Hinge mechanism 41 Paper feed unit 42 Paper feed roller 43 Paper transport path 44 Transport roller 45 Ejection roller 46 Ejection space 51 Liquid crystal display unit 52 Operation button 61 Photosensitive drum 62 Charging unit 63 Exposure unit 64 Image formation unit 65 Transfer Section 66 Fixing section 67 Cleaning section 71 Document size determination section

Claims (3)

An image forming apparatus that scans a document placed on a platen glass while moving a scanner in which a plurality of LEDs are arranged in a main scanning direction as a light source in a sub scanning direction, and reads image data,
First opening / closing detection means for detecting the opening of a platen cover covering the platen glass;
Second opening / closing detection means for detecting opening of the platen cover at a preset threshold angle;
When the opening / closing of the platen cover is detected by the first opening / closing detection unit without the opening at the threshold angle being detected by the second opening / closing detection unit, the main scanning direction of the plurality of LEDs is detected by the scanner. The near side position determination data is obtained by acquiring the near side position determination data by the near side position determination scanning in which only a part of the back side is lit, and at the same time, only a part of the plurality of LEDs on the near side in the main scanning direction is lit. Document size determination means for acquiring back side position determination data by scanning, and determining a document size in the main scanning direction based on the acquired near side position determination data and the back side position determination data. An image forming apparatus. In the front side position determination scanning, the LED in a range narrower than the minimum width of the assumed document size is turned on from the back side in the main scanning direction,
The image forming apparatus according to claim 1, wherein in the back side position determination scanning, the LED in a range narrower than a minimum width of an assumed document size is turned on from the front side in the main scanning direction.   The document size determination means includes the near-side position determination data in the range exceeding the maximum length assumed in the document in the sub-scanning direction from the sub-scanning direction reference line for aligning the document in the sub-scanning direction or the back side. The side position determination data is acquired by the front side position determination scan or the back side position determination scan, and the document size in the sub-scanning direction is determined based on the acquired determination data. The image forming apparatus according to 1 or 2.

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