JP2010141856A - Manuscript reading device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manuscript reading device which can remove an effect to an user due to light emission of a light-emitting element when prescanning is carried out and which can also correctly determine the size of a manuscript that is uncertain in size or a manuscript that is located at a position shifted from a reference position of a manuscript mounting base, and to provide an image forming device using the same. <P>SOLUTION: The image reading device 1 includes a transparent manuscript mounting base 11, a manuscript cover 14 which is located to be freely closable/openable on the manuscript mounting base 11, a manuscript scanner unit 13, and a control means 6. The manuscript scanner unit 13 has a manuscript irradiating light source 7 in which a plurality of light-emitting elements 72 are arranged in the main-scanning direction and a photoelectric conversion element 18 which detects the reflection light from the manuscript D by the light source 7. The control means 6 lights on the plurality of light-emitting elements 72 in order while closing the manuscript cover 14, detects a part of a shadow DS at the edge of the manuscript by the photoelectric conversion element 18, and thereby, determines the size of the manuscript in the main-scanning direction on the manuscript mounting base 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an original reading apparatus that reads an image of an original placed on a transparent original placing table by an original scanner unit, and an image forming apparatus using the original reading apparatus.

  An image forming apparatus such as a copying machine, a facsimile machine, or a so-called multi-function machine including a printer function having a document reading device has a function of automatically determining the size of a document placed on a document placement table. ing. In FIGS. 13 and 14 of Patent Document 1 (conventional example of the invention of Patent Document 1), light is emitted from a light emitting element of a reflective sensor to a document placed on a document table in accordance with the document reference. In this example, the presence or absence of reflected light from the document surface is detected by a light receiving element of a reflective sensor, and the document size is detected by a combination of the presence or absence of the reflected light. Further, in Patent Document 1, in order to solve the problems in this conventional example, a point light source element (for example, LED) of a point light source array illumination for reading a document is divided into a plurality of blocks, and the minimum document size on the document reference side is divided. Each block is turned on and off sequentially from the corresponding block to the block on the maximum original size side, and the original is determined by which light-receiving element responds to the reflected light from the original at the time of lighting. It has been proposed to detect the size.

JP 2005-156638 A

  In the case of the document size detection method disclosed as the prior art in Patent Document 1, since the number of reflection sensors to be installed is limited, the size of a deformed document is determined and the document is placed on the document table. Cannot handle document size determination. In the document size detection method according to the invention described in Patent Document 1, it is necessary to detect the document size by pre-scanning with the point light source array illumination sequentially turned on for each block with the document cover opened. Therefore, there is a problem that the light from the LED enters the user's eyes, a problem that the user feels glare, a problem that the document size is erroneously detected depending on the opening / closing speed of the document cover, and a detection method for each block. Therefore, there is a limit to the number of recognition, and there is a problem that the size of the original cannot be determined in the case of an irregular-size original or an original placed at a position shifted from the reference position of the original table.

  The object of the present invention is to eliminate the influence on the user due to light emission of the light emitting element during pre-scanning, and to accurately measure the size of an irregular-size document or a document placed at a position shifted from the reference position of the document table. An object of the present invention is to provide a document reading apparatus that can be discriminated and an image forming apparatus using the same.

The present invention provides a document reading unit that includes a transparent document table, a document cover that can be opened and closed on the document table, a document scanner unit that is installed under the document table, and a control unit. In the device
The document scanner unit includes a document irradiation light source in which a plurality of light emitting elements are arranged in a main scanning direction, and an image detection unit that detects reflected light from the document by the light source,
The control means includes
With the document cover closed,
The plurality of light emitting elements are sequentially turned on, and the image detecting unit detects a shadow portion at the edge of the document on the document table, thereby determining the document size in the main scanning direction on the document table. An original reading apparatus characterized by the above.

  Further, the invention is characterized in that the light emitting element is arranged so as to irradiate light on the original from an oblique direction.

  In the invention, it is preferable that the control unit discriminates the document size based on a detection result of a shadow portion by both ends in the main scanning direction of the document.

  In the invention, it is preferable that the control unit moves the light source in the sub-scanning direction with the number of light emitting elements corresponding to the determined document size turned on, while moving the light source on the document placement table. The operation of the document scanner unit is controlled so as to perform a reading operation.

  According to the present invention, in the reading operation of the document image, the control unit detects a shadow portion due to an edge of the document in the sub-scanning direction, whereby the document size of the document in the sub-scanning direction is detected. It is characterized by distinguishing.

  The present invention also provides the above document reading device, an image recording unit that records an image on a recording medium based on image information read by the document reading device, and a recording medium supply unit that supplies the recording medium to the image recording unit And an image forming apparatus.

  According to the present invention, an image of a document placed on a transparent document placement table is read by a document scanner unit installed at the bottom of the document placement table. Then, the document is placed on the document table, the plurality of light emitting elements are sequentially turned on with the document cover closed, and the shadow of the document edge is detected by the image detecting means. Since the document size in the main scanning direction on the mounting table is determined, it is possible to prevent the user from directly viewing the light of the bright light source. In addition, since the edge of the document is substantially detected, accurate determination can be made even if the document is indefinite. In addition, since the shadow is detected with the document cover closed, the document does not float, the position of the edge of the document does not vary from the position of the shadow, and the document size in the main scanning direction is determined. Is made with high accuracy. Further, since the light source for reading a document is used for determining the size of the document, it is not necessary to install a dedicated sensor or the like for size detection, thereby saving space and reducing the cost of the apparatus.

  According to the invention, since the light emitting element is arranged so as to irradiate light from an oblique direction with respect to the document on the document table, a shadow due to irradiation is likely to be generated at the document edge portion. The edge shadow is reliably detected, and the document size in the main scanning direction can be determined with higher accuracy.

  According to the invention, since the control unit determines the document size based on the detection result of the shadow portion at both ends in the main scanning direction of the document, by calculating the distance between the shadow portions at both ends. Even if the original document is deviated from the reference position, the original document size in the main scanning direction can be accurately determined.

  According to the invention, the control unit moves the light source in the sub-scanning direction with the number of light emitting elements corresponding to the determined document size turned on, and the document image on the document placement table. Since the operation of the original scanner unit is controlled so as to perform the reading operation, the number of light emitting elements to be lit is set for each original size, and there is no useless lighting of the light emitting elements, thereby saving power consumption during image reading. In addition, the life of the light-emitting element can be extended. In this case, since the image detecting means detects the shadow portion at the edge of the document in the sub-scanning direction, the document size in the sub-scanning direction of the document is discriminated. By determining the size, the entire size of the document is accurately determined.

  According to the invention, the image information of the document placed on the document placement unit is read by the document reading device, and the image based on the image information is recorded on the recording medium by the image recording unit. At this time, in the image reading apparatus, the size of the document placed on the document placement unit is determined by pre-scanning the document reading light source with the document cover closed, and based on the determination result, the size of the corresponding document is determined. A recording medium is supplied from a recording medium supply unit, and an image is recorded in the image recording unit. Therefore, when the user performs a copy operation at the side of the image forming apparatus, the irradiation light during the pre-scan does not enter the eyes, and the user does not feel discomfort due to glare. In addition, since the document size is accurately determined, the control unit can control the operation so as to appropriately supply the recording medium of the corresponding size from the recording medium supply unit.

  FIG. 1 is a longitudinal sectional view showing a configuration of an image forming apparatus A including an image reading apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, an image reading device (image reading unit) 1 includes a document placing table 11 made of transparent glass, and a double-sided automatic document feeder for reading a document image while automatically supplying a document. RADF) 12, a document reading device for scanning and reading an image of a document placed on the document placement table 11, that is, a document scanner unit 13.

  The RADF 12 sets a plurality of documents at once on a predetermined document tray, and automatically loads the set documents one by one on the document placing table 11 of the scanner unit 13. It is a known device for feeding to The RADF 12 includes a conveyance path for a single-sided document, a conveyance path for a double-sided document, a conveyance path switching unit, and the like so that the scanner unit 13 can read one or both sides of the document according to a user's selection. Has been. When the original image is read using the RADF 12, the first scanning unit 15 and the second scanning unit 16 (both described later) constituting the original scanner unit 13 are arranged on one side on the original placement table 11. The image of the original passing through the automatic feeding original reading section is sequentially read. FIG. 1 shows a state in which the first scanning unit 15 and the second scanning unit 16 are stationary on the reading section of the automatically fed document. The RADF 12 is provided integrally or separately on a document cover 14 that is installed on the document table 11 so as to be openable and closable. The document cover 14 is used to press a document placed on the document table 11 and prevent the document from being lifted, and the upper surface of the document cover 14 is a discharge tray 140 for automatically fed documents.

  The scanner unit 13 includes a lamp reflector assembly that exposes the surface of a document, and a photoelectric conversion element (for example, a charge coupled device (CCD) or a close contact) as image detection means that converts a reflected light image from the document into an electrical image signal. First scanning unit 15 equipped with a first reflecting mirror for guiding the image sensor 18 to a type image sensor (CIS) 18 and a second scanning unit 16 equipped with second and third reflecting mirrors, and the reflected light image on the photoelectric conversion element 18. The optical lens body 17 is used to form an image. The first scanning unit 15 has a document irradiation light source 7 which will be described later, travels along the document placing table 11 from left to right in FIG. 1 at a constant speed V, and the second scanning unit 16 has a speed of 1 / 2V. The scanning is controlled so as to travel in the same direction. As a result, the image reading unit 1 moves the scanner unit 13 along the lower surface of the document placing table 11 while placing the document to be read on the document placing table 11 in order, and places the document on the document placing table 11. The original image is sequentially imaged on the photoelectric conversion element 18 for each line, and the original image is read.

  The image data obtained by reading the document image with the scanner unit 13 is subjected to various processes and then temporarily stored in the memory. The image data is output from the memory to the image recording unit 2 in accordance with an output instruction. After being reproduced as a visible image on the photosensitive drum 22, the image is transferred onto a sheet (recording medium) to form a toner image. The image recording unit 2 includes a laser writing unit (LSU) 21 and an electrophotographic process unit 20 for forming an image. The laser writing unit 21 is a semiconductor laser that emits laser light in accordance with image data read from a memory or image data transferred from an external device such as a personal computer, a polygon mirror that deflects the laser light at a constant angular velocity, and a constant angular velocity deflection. It has an f-θ lens and the like that corrects the laser beam thus scanned on the photosensitive drum 22 of the electrophotographic process unit 20 at a constant speed. In the electrophotographic process unit 20, a charging device 23, a developing device 24, a transfer device 25, and a cleaning device 26 are arranged around the photosensitive drum 22 according to a well-known aspect, and a fixing device 27 is further downstream of the photosensitive drum 22. Arranged.

  The paper feed unit (recording medium supply unit) 3 includes first to third cassettes 31 to 33 and a manual feed tray 35 that can stack a large number of recording sheets. Pickup rollers 31 a to 33 a and 35 a for feeding the uppermost stacked sheets one by one are installed at the front end of the first to third cassettes 31 to 33 and the manual feed tray 35. The paper feed rollers 31b to 33b and 35b are respectively installed near the downstream side in the direction. The sheet feeding rollers 31b to 33b, 35b are joined at the downstream side in the sheet feeding direction to form a sheet feeding / conveying unit 4. The sheet feeding / conveying unit 4 includes conveying rollers 41, 42, 43, 44 and a registration roller 45. The paper fed from the first to third cassettes 31 to 33 and the manual feed tray 35 passes through one of the transport rollers 41, 42, and 43 and reaches the registration roller 45 from the transport roller 44. The toner is registered by the roller 45 and conveyed to the transfer position between the photosensitive drum 22 and the transfer device 25.

  In FIG. 1, as indicated by a two-dot chain line, a large-capacity cassette 34 is optionally installed as a fourth cassette under the third cassette 33, and the paper feeding / conveying section 4 is connected to the large-capacity cassette. A sheet fed from the large-capacity cassette 34 is also connected to the sheet feeding side 34 and is transported toward the transfer position by a transport roller 41. In other words, the four trays in the first to fourth cassettes 31 to 34 in the paper feeding unit 3 store and store the sheets for each size, and the cassettes store the sheets of the size desired by the user. Alternatively, when the manual feed tray 35 is selected or automatically selected based on the size information of the image data to be recorded, it is fed out one by one from the top of the sheet bundle in the selected tray, The images are sequentially conveyed toward the electrophotographic process unit 20 via the conveyance path. The transport path of the paper feed transport unit 4 passes through the transfer position to the fixing device 27, and a paper discharge path 5 is provided on the downstream side of the fixing device 27 in the paper transport direction.

  In the laser writing unit 21 and the electrophotographic process unit 20, image data read from the memory or image data transferred from an external device such as a personal computer is scanned by a laser beam by the laser writing unit 21. The toner image formed as an electrostatic latent image on the surface of the photosensitive drum 22 and visualized by the toner of the developing device 24 is transferred onto the surface of the paper fed and conveyed from the paper feeding unit 3 by the transfer device 25. It is electrostatically transferred and fixed by the fixing device 27. The sheet on which the image is formed in this manner is sent from the fixing device 27 to the stacking tray 50 through a conveying roller 51 provided in the sheet discharge path 5 and a discharge roller 52 that can rotate forward and backward. A switching gate 53 is provided in the paper discharge path 5 between the conveying roller 51 and the discharging roller 52, and the upstream side of the conveying roller 44 is connected to the paper feeding / conveying section 4 with the installation portion of the switching gate 53 as a base point. A re-feed conveyance section 54 that joins is connected.

  The sheet on which the image is recorded is conveyed further upward by the conveying roller 51 through the fixing device 27 and passes through the switching gate 53. When the paper transport destination is set to the stacking tray 50, the paper is discharged to the stacking tray 50 by the forward rotation of the discharge roller 52. On the other hand, when double-sided image formation or post-processing is designated, the paper is once discharged toward the stacking tray 50 by the discharge roller 52. In this case, the paper is not completely discharged, the discharge roller 52 is temporarily stopped, the rear end of the paper is held between the discharge rollers 52, and then the discharge rollers 52 are rotated in reverse. As a result, the sheet is reversely conveyed in the reverse direction, that is, in the direction of the refeed conveyance unit 54 that is selectively mounted for double-sided image formation or post-processing. At this time, the switching gate 53 is switched from upward to downward. A switching gate 55 for post-processing (stapling, punching, etc.) is provided in the middle of the re-feeding conveyance unit 54. When the post-processing mode is selected, the reverse conveyance is performed by switching the switching gate 55. The sheet thus fed is sent to the post-processing section, subjected to stapling and punching processing, and then discharged onto the post-processing tray 56. When performing double-sided image recording, the reversely conveyed sheet passes through the refeed conveyance unit 54, is conveyed by conveyance rollers 57, 58, and 59 arranged in the middle, and again passes through the registration roller 45 to be stored in the image recording unit 2. The image is supplied to the transfer position and image recording is performed on the back surface.

  FIG. 2 is a control block diagram of the image forming apparatus A of the present invention. The image forming apparatus A according to the present embodiment includes a CPU 6, a RAM 61, a ROM 62, an illumination lamp (original illuminating light source) 7 constituting the image reading unit 1 and a driving unit (driving circuit) 70, a CCD or a CIS (contact image sensor). ) And the like, and an A / D converter 180 for digitally converting the detected analog data, each drive circuit (not shown) (the other drive circuit of the image reading unit 1, each of the transport rollers, etc.) , A drive circuit for the sheet conveyance system including the drive circuit for the image recording unit 2), an operation panel controller, an operation panel, and various detection sensors. When the image forming apparatus A is a so-called multi-function machine having a facsimile function and a printer function, a facsimile engine and a printer controller are also provided. The CPU 6 is a central control unit that controls the overall operation of the image forming apparatus A. The RAM 61 is used as a working area for the CPU 6. The ROM 62 stores a program for the CPU 6 to execute.

  FIG. 3 is a diagram illustrating a schematic configuration of the document illumination unit of the image reading unit 1. The illumination lamp 7 is arranged below the document placement table 11, and has a large number of points on the array substrate 71 along the main scanning direction. The example using the point light source array (for example, LED array etc.) which arranged the light emitting element (for example, white LED etc.) 72 ... for light sources is shown. As shown in FIG. 4, the illumination lamp 7 has a number of white LEDs 72 arranged on a long array substrate 71 in a line along the longitudinal direction. The length is set to be equal to or longer than the length in the width direction of the table 11 (the length of the document reference scale at the left end of the document table 11 in FIG. 1). FIG. 3 shows a procedure for placing the document D on the document table 11 and pre-scanning to determine the width of the document D in the main scanning direction before reading the document image, as will be described later. That is, the document D is placed on the document table 11 with the image surface facing downward, and the LED 72 of the illumination lamp 7 is sequentially turned on with the document cover 14 closed to irradiate the document D. At the end of the document D, a shadow DS of the irradiated light is generated on the cover surface of the document cover 14. The photoelectric conversion element 18 detects the shadow DS, and the CPU 6 recognizes the edge of the document D based on the detection information of the shadow DS and determines the size of the document D in the main scanning direction. FIG. 3 shows that the LED 72 with cross hatching is turned off and the white LED 72 is turned on. The LED 72 is arranged so that light is irradiated obliquely with respect to the document D.

  As shown in FIG. 3, when the LEDs 72 of the illumination lamp 7 are sequentially turned on in the direction indicated by the arrow 73, they are separated from the lit LEDs 72 due to the light emission characteristics of the LEDs 72 unless they are shadows DS of the document D. Although the brightness of the position is determined, the portion where the document D is present has a shadow DS, and a portion darker than the light emission characteristics of the LED 72 is generated. In the case of image data, since the density does not change depending on the irradiation angle, it is possible to determine whether the image on the original D or the shadow of the edge of the original D is an image by the adjacent LED 72. Further, when the image is acquired by turning on the LED 72 as described above, the image data is not acquired as many times as the number of the LEDs 72, but the LEDs 72 that are not affected by each other are turned on at the same time. It is desirable to minimize the number.

  FIG. 6 shows a flowchart of a process for recognizing both ends (two places) of the document D while pre-scanning as described above. In step S1, it is detected that the document D is placed on the document table 11 and the document cover 14 is closed. Whether or not the document cover 14 is closed can be detected by a known detection technique.

  In step S2, one white LED 72 is turned on to illuminate the document D with the positional relationship shown in FIG. The reflected light at that time is recognized, and it is determined whether or not there is a shadow on the edge of the document (step S3). If there is no shadow at the document edge, the next white LED 72 is turned on, and the process returns to step S2. If there is a shadow at the edge of the document, the position is stored and the process proceeds to step S4. In step S4, the next white LED 72 that has recognized the shadow of the document edge in step S3 is turned on, and one white LED 72 is turned on to illuminate the document D in the same manner as in step S2. The reflected light at that time is recognized, and it is determined whether or not there is a shadow on the edge of the document (step S5). If there is no shadow at the document edge, the next white LED 72 is turned on, and the process returns to step S4. If there is a shadow at the edge of the document, the position is stored and the process ends. The distance between the positions recognized in steps S3 and S5 is the size of the document.

  As described above, when the white LEDs 72 are sequentially irradiated from the edge one by one to the image reading surface of the document from an oblique direction and the state is read by the photoelectric conversion element 18 (CCD or CIS), the cover of the document cover 14 is covered. An electric signal level close to white is obtained at the surface and the portion of the original D, but when the light from the white LED 72 is obliquely applied to the end of the original as shown in FIG. 3, a shadow DS is generated, which is photoelectrically converted. When read by the element 18, an electrical signal close to black is obtained because of the shadow only at the position of the document edge. FIG. 5 shows changes in the electric signal level by the photoelectric conversion element 18 of the light reflected from the document D by sequentially turning on the white LEDs 72. The horizontal axis indicates the position of the white LED 72 along the main scanning direction. Each axis represents an electric signal level. As shown in FIG. 5, the wedge-shaped portion of the graph is the document edge, and the CPU 6 detects and discriminates the distance between the two locations as the document size in the width direction (main scanning direction). In this way, since both ends of the document D in the width direction are detected and the document size is determined, the document size can be accurately determined regardless of whether the document D is a regular paper or an irregular paper. Even if the document D is placed out of the reference position, the size of the document D is determined.

  After the determination of the document size detection in the main scanning direction, the first scanning unit 15 and the second scanning unit 16 in the document scanner unit 13 with the white LED 72 in the document scanning region in the main scanning direction in the illumination lamp 7 turned on. Is moved in the sub-scanning direction, and the image of the document D on the document table 11 is read. FIG. 7 shows this image reading state, and the illumination lamp 7 runs in a direction perpendicular to the paper surface. In FIG. 7, as in the case of FIG. 3, the white LED 72 with cross-hatching indicates a light-off state and the white LED 72 indicates a light-on state, and the illumination lamp 7 travels in the sub-scanning direction in this state while the original is being scanned. The image surface of D is illuminated, the reflected light image is formed on the photoelectric conversion element 18, and the original image is read.

  In parallel with this image reading operation, the size of the document D in the sub-scanning direction is determined. FIG. 8 shows a flowchart of a process for recognizing the size of the document D in the sub-scanning direction. After completion of the recognition of the document size in the main scanning direction (step S11), in step S12, as shown in FIG. 7, the white LED 72 in the illumination lamp 7 corresponds to the determined document width region in the main scanning direction. The first scanning unit 15 and the second scanning unit 16 are moved and moved in the sub-scanning direction with the traveling pattern (traveling speed V and 1 / 2V) while only the portion to be lit is turned on, and the document is moved during the traveling movement. The surface is scanned, and the original image based on the reflected light is read by the photoelectric conversion element 18. In the read document image, if the end portion in the sub-scanning direction can be recognized (step S13), the position is stored and the process ends. This position is the size of the document D in the sub-scanning direction. The end portion is recognized by recognizing the shadow DS by the document end portion in the same manner as shown in FIG.

  By discriminating the width (size) of the document D in the main scanning direction as described above, the number of white LEDs 72 corresponding to the size of the document D in the main scanning direction are turned on, and the image of the document D is read. The power consumption can be saved as compared with the case where all the white LEDs 72 are turned on, and the lifetime of the white LEDs 72 can be extended. In the above operation, the size between both ends of the document D in the main scanning direction can be recognized at the signal level. It is possible to detect the size in the scanning direction.

  In the illustrated embodiment, the writing unit 21 is based on the laser method, but may be an LED (light emitting diode) method. Moreover, although white LED was illustrated as a light emitting element which comprises the illumination lamp 7, other light emitting elements may be sufficient. Further, the RADF 12 in the image reading apparatus 1 shown in FIG. 1 is a type in which a document image is read by a stationary document scanner unit 13 while automatically supplying a document, but the document automatically supplied by the ADF is temporarily stored on the document placement table. 11 may be of a type in which a document image is read by moving the document scanner unit 13 under the movement of the document scanner unit 13. In addition, the image reading apparatus of the present invention can be applied to an image forming apparatus that does not have an image recording unit, such as a scanner-dedicated machine and a transmission-dedicated facsimile apparatus. In this case, the document size discrimination information is useful information for a personal computer or a facsimile receiver connected thereto.

1 is a longitudinal sectional view illustrating a configuration of an image forming apparatus A that is an embodiment of the present invention. 3 is a control block diagram of the image forming apparatus A. FIG. FIG. 2 is a diagram schematically illustrating a configuration of a document illumination unit of an image reading unit 1 in the image forming apparatus A, and schematically illustrating a state in which an illumination lamp 7 is pre-scanned in order to determine the size of a document D in the main scanning direction. . 3 is a schematic perspective view of the illumination lamp 7. FIG. It is a graph which shows the electric signal level of the detection reflected light at the time of pre-scanning the illumination lamps 7 and 8 for document size discrimination | determination. FIG. 6 is a flowchart of an operation for determining the size of a document D in the main scanning direction. FIG. 6 is a diagram schematically showing a lighting state of an LED 72 when reading and scanning an image of a document D. FIG. 6 is a flowchart of an operation for determining the size of a document D in the sub-scanning direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Image recording part 3 Recording medium supply part 6 Control means 7 Original light source 11 Original placing table 13 Original scanner unit 14 Original cover 18 Photoelectric conversion element 72 Light emitting element A Image forming apparatus D Original DS By original edge part Shadow

Claims (6)

In a document reading apparatus, comprising: a transparent document placing table; a document cover that can be freely opened and closed on the document placing table; a document scanner unit that is disposed at a lower portion of the document placing table; and a control unit.
The document scanner unit includes a document irradiation light source in which a plurality of light emitting elements are arranged in a main scanning direction, and an image detection unit that detects reflected light from the document by the light source,
The control means includes
With the document cover closed,
The plurality of light emitting elements are sequentially turned on, and the image detecting unit detects a shadow portion at the edge of the document on the document table, thereby determining the document size in the main scanning direction on the document table. An original reading apparatus characterized by the above.   The document reading apparatus according to claim 1, wherein the light emitting element is disposed so as to irradiate the document with light from an oblique direction.   3. The document reading apparatus according to claim 1, wherein the control unit determines the document size based on a detection result of a shadow portion by both ends of the document in a main scanning direction.   The control means performs an operation of reading a document image on the document table while moving the light source in the sub-scanning direction with a number of light emitting elements corresponding to the determined document size being lit. 4. The document reading apparatus according to claim 1, wherein operation control of the document scanner unit is performed.   In the reading operation of the document image, the control unit determines the document size in the sub-scanning direction of the document by the image detecting unit detecting a shadow portion at the end of the document in the sub-scanning direction. 5. The document reading apparatus according to claim 4, wherein   6. The document reading device according to claim 1, an image recording unit that records an image on a recording medium based on image information read by the document reading device, and a recording medium in the image recording unit. An image forming apparatus comprising: a recording medium supply unit that supplies the recording medium.

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