JP2008245209A - Scanner device and image forming apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce manufacturing costs by allowing a scanner device to read an original without requiring a sheet detection sensor or a sheet edge detection sensor. <P>SOLUTION: A scanner unit 3 reads an original placed on an original platen 3a or a document fed onto a transmission plate 3b by an auto document feeder (ADF) 20 using a contact image sensor (CIS) or the like within a scanner housing 12. The ADF 20 feeds the document fed from an upper part of a document cover 11 using a feeding roller 21. In the ADF 20, an identification pattern 25 is formed at a portion that is imaged by the CIS through the transmission plate 3b. When starting reading the document, the feeding roller 21 is turned while imaging a surface of the transmission plate 3b using the CIS. When imaged data are changed from data indicating the identification pattern 25 within a predetermined period of time, it is judged that the document is being fed, and the document is read using the ADF 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scanner device having a function of reading a document as image data while conveying the document, and an image forming apparatus using the scanner device.

  2. Description of the Related Art Conventionally, there is a scanner device that reads a plurality of documents loaded on a document tray as image data while sequentially conveying a plurality of documents by an auto document feeder (hereinafter referred to as ADF). Such a scanner device is provided with a sheet presence / absence detection sensor in the document tray, detects that a document is placed / loaded in the document tray, or includes a sheet end detection sensor in the document transport path in the ADF, It is configured so that the position of the leading edge of the conveyed document can be detected and the document can be properly read from the leading edge to the trailing edge. However, when the sensor for detecting the presence / absence of the document and the position of the document is provided as described above, the number of parts of the scanner device increases, and the manufacturing cost of the scanner device increases.

  Here, in Patent Document 1, the position of the front end of the original is detected by detecting a shadow formed on the front end of the original conveyed to the white reference roller, and the reading start position of the original is detected even if the original slips during conveyance. A facsimile machine is shown which is not misaligned. Also, in Patent Document 2, an opening that is blocked by the passage of a document is provided in a portion where the document is read, and an image is captured by CIS or the like to determine whether or not the leading end of the document has reached the opening. A facsimile apparatus that detects the position of the leading edge of a document by reading is shown. However, in order to reliably detect the position of the leading edge of the document as disclosed in Patent Document 1, a white reference roller must be provided at a portion where the document is read. When the conveyance roller is provided only in the central portion, the detection accuracy of the position of the leading edge of the document may be lowered. Further, in Patent Document 2, since an opening is provided in a guide member that presses the document toward a portion where the document is read, the opening cannot be enlarged or the number of openings cannot be increased, and the detection accuracy of the position of the document leading edge is improved. Hard to raise. Furthermore, Patent Document 1 and Patent Document 2 do not show a mechanism for detecting that a document is placed on a document tray.

Patent Document 3 discloses an image forming apparatus configured to be able to read a predetermined mark formed on a document sheet and determine whether the image on the document sheet is a valid image accordingly. However, Patent Document 3 does not disclose a configuration that can be used in place of a sensor for detecting the presence or absence of a document and the position of the document, which can be an effective solution to the above problem. .
JP 2005-57483 A JP 2003-319140 A JP 2006-135383 A

  The present invention has been made in view of the above-described problems, and can provide a scanner device that can read an original without requiring a paper presence / absence detection sensor or a paper edge detection sensor, and can reduce manufacturing costs. An object of the present invention is to provide an image forming apparatus used.

  In order to achieve the above object, the invention of claim 1 includes a scanner unit disposed above a printer housing and image data of a document that is disposed below the scanner unit and read by the scanner unit or input from an external device. An image forming unit that forms an image on a recording sheet based on the image data, and a control unit that controls the operation of the scanner unit and the image forming unit. The scanner unit includes a scanner housing and the scanner. A substantially rectangular document table disposed on the upper surface of the housing, a transmission plate disposed in the vicinity of the side of the document table, and opening and closing the scanner housing so as to cover the document table and the transmission plate A document cover provided freely, and a transport roller provided on the document cover for transporting the document, is rotated on the document tray on the upper surface of the document cover. Among the prepared originals, the one in contact with the upper surface of the original cover is conveyed to the transmission plate and brought into contact with the upper surface of the transmission plate, and the original conveyed to the transmission plate is placed on the original cover. An auto document feeder for discharging onto the document cover from above, and an image reading unit housed in the scanner housing and capable of imaging the surface of the document table or the transmission plate. When the document is read, when the document is placed on the document tray, the control unit performs a reading operation of the document conveyed by the auto document feeder by the image reading unit, and reads the document on the document tray. When the image reading unit is not placed, the image reading unit is scanned while being brought into contact with the document table to perform a document reading operation on the document table. In the image forming apparatus, a portion of the auto document feeder that is substantially fixed to the document cover and faces the transmission plate when the document cover is in a closed state is placed on the transmission plate by the image reading unit. An identification pattern is provided in which a plurality of points that can be imaged via a line are arranged in a substantially straight line in a direction substantially orthogonal to the document conveyance direction, and the identification pattern has a plurality of types of chromatic colors. The control unit rotates the conveyance roller for a predetermined period while imaging the surface of the transmission plate by the image reading unit during document reading, and the image reading unit while rotating the conveyance roller. When the imaging data of the document is changed from the imaged image of the identification pattern, the front end of the document placed on the document tray and being conveyed is the transmission plate. Until the imaging data of the image reading unit indicates the identification pattern, the imaging of the surface of the transmission plate is continued while rotating the conveying roller, and the conveying roller is rotated. If the image data of the image reading unit does not change from the image obtained by capturing the identification pattern while the image is being scanned, it is determined that no document is placed on the document tray, and the image reading unit The automatic document feeder is configured to perform a reading operation of a document, whereby a sensor for detecting that the document is placed on the document tray and a sensor for detecting the position of the conveyed document are provided in the auto document feeder. There is no need to provide a document, and it is possible to execute reading of a document using the auto document feeder and reading of a document on the document table with a simple configuration. Those were.

  According to a second aspect of the present invention, the image reading unit disposed on the back side of the transmission plate and the document placed on the document tray are rotated by rotating a transport roller so as to capture the surface of the transmission plate. In a scanner apparatus including an auto document feeder that sequentially conveys to a transmission plate, and a control unit that controls the image reading unit and the auto document feeder and reads the original as image data, of the auto document feeder, An identification pattern that can be imaged by the image reading unit is provided in a portion facing the surface, and the control unit captures the surface of the transmission plate while imaging the surface of the transmission plate by the image reading unit during document reading. The image data of the image reading unit imaged the identification pattern while rotating the roller for a predetermined period and rotating the transport roller When the change is changed, the imaging of the surface of the transmission plate is continued while rotating the transport roller until the imaging data of the image reading unit shows the identification pattern. .

  The invention of claim 3 is the invention of claim 2, wherein the identification pattern has a plurality of types of chromatic colors.

  According to a fourth aspect of the present invention, in the second or third aspect of the present invention, an original platen that is disposed near a side portion of the transmission plate and on which a document can be placed, the original platen and the transmission plate, The auto document feeder is disposed on the document cover so as to correspond to the transmission plate, and the image reading unit includes the document table or the document cover. The upper surface of the transmission plate is provided so as to be able to image, and the control unit changes the image data of the image reading unit from the image of the identification pattern while rotating the transport roller during image reading. If not, it is determined that no document is placed on the document tray, and the image reading unit reads the document on the document table.

  According to the first aspect of the present invention, when the control unit rotates the conveying roller for a predetermined period when reading the document and the imaging data of the image reading unit changes from the one indicating the identification pattern, the document is placed on the document tray. In addition, the image reading unit continues imaging until the imaging data indicates an identification pattern. Accordingly, the document can be read with a simple configuration without providing a sensor for detecting the presence or absence of the document on the document tray and the position of the document, and the manufacturing cost of the image forming apparatus can be reduced. In addition, since the identification pattern has a plurality of points arranged in a substantially straight line in a direction substantially orthogonal to the document transport direction and has a plurality of types of chromatic colors, the image data and document when the identification pattern is captured Can be reliably distinguished from each other when the image is captured, and the position of the document can be detected more reliably by detecting the edge of the document, and the document can be read more appropriately. . Furthermore, when the image pickup data of the image reading unit does not change from the one indicating the identification pattern while rotating the transport roller during document reading, the control unit performs the document reading operation on the document table. It is possible to automatically determine whether to read an image using a document feeder or to read an original on a platen, and to read the original, so that the image forming apparatus can detect the presence of an original on the original tray. It is possible to use more conveniently while providing a simple and low-cost configuration without a sensor.

  According to the second aspect of the present invention, when the control unit rotates the conveying roller for a predetermined period during document reading and the imaging data of the image reading unit changes from the one indicating the identification pattern, the imaging data is identified from that time. Since the image reading by the image reading unit is continued until the image is displayed, the document can be read with a simple configuration as described above, and the manufacturing cost of the scanner device can be reduced.

  According to the invention of claim 3, since the identification pattern has a plurality of types of chromatic colors, it is possible to reliably distinguish the imaging data when the identification pattern is imaged from the imaging data when the document is imaged. Thus, the edge of the document can be detected more reliably, the position of the document can be detected, and the document can be read properly.

  According to a fourth aspect of the present invention, when the image pickup data of the image reading unit does not change from the one showing the identification pattern while the transport roller is rotated during document reading, the control unit reads the document on the document table. Since the operation is performed, it is possible to automatically determine whether to perform image reading using the auto document feeder or to read the document on the document table and read the document. Therefore, the scanner device can be used more conveniently while having a simple and low-cost configuration that does not include a sensor for detecting the presence or absence of a document on the document tray.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an image forming apparatus according to this embodiment. The image forming apparatus 1 is of a so-called all-in-one type, and includes an image forming unit 2 housed in a resin-made printer housing 10 and a rear end of the image forming device 2 above the printer housing 10. 10 is arranged in a state of being pivotally supported so as to be horizontally rotatable, and is arranged in a substantially rectangular parallelepiped scanner unit 3 (scanner device) for reading a document as image data and a front portion of the printer housing 10 as will be described later. An operation button 4 that can be operated from the outside, a liquid crystal display unit 5 that displays the operating state of the image forming apparatus 1, and an external device such as a digital still camera or a memory card that are disposed on the front surface of the printer housing 10 And a control unit 9 that is configured by a CPU, a memory, and the like, and that controls the operation of each unit such as the image forming unit 2 and the scanner unit 3. The operation buttons 4 and the liquid crystal display unit 5 are disposed on an operation panel 10a provided in the front of the printer housing 10 so as to be opened and closed. When the image forming apparatus 1 is stored, the operation panel 10a is closed and externally provided. It is configured so that it can be kept from being exposed.

  A paper feed tray 15 on which recording paper (not shown) to be conveyed to the image forming unit 2 is loaded is provided on the back surface of the printer housing 10, and an image forming unit is provided on the front surface of the image forming unit 2. A paper discharge tray 16 is provided on which the recording paper on which the image 2 is formed is discharged. A document cover 11 is provided on the upper portion of the scanner unit 3 so as to be openable and closable with respect to the scanner housing 12 so as to cover the upper surface of the scanner housing 12 configured separately from the printer housing 10. An auto document feeder (hereinafter referred to as ADF) 20 that is used when continuously reading a plurality of documents is disposed on the scanner unit 3. The upper surface of the document cover 11 also serves as a document tray 28 on which documents conveyed by the ADF 20 are placed as will be described later. The ADF 20 has a function of sequentially transporting documents placed on the document tray 28 to the scanner unit 3 in a readable manner. In the present embodiment, the ADF 20 is disposed on the upper side of the document cover 11. The image forming apparatus 1 is controlled by the control unit 9, for example, an external device connected to the connector unit 8 or the like, or an external personal computer connected via a connector provided on the back of the printer housing 10, for example. The image forming unit 2 has a function of forming an image on a recording sheet using image data input from the above or the like or image data read by the scanner unit 3.

  The image forming unit 2 forms an image on a recording sheet by a so-called inkjet method. For example, the image forming unit 2 feeds recording sheets one by one from the paper feed tray 15 into the printer housing 10 and discharges them onto the paper discharge tray 16, a recording medium having a motor that drives the rollers, and the like. A carriage 2a equipped with a paper transport mechanism (not shown), a head for ejecting ink onto the recording paper transported inside the printer housing 10, and the carriage 2a reciprocating in a direction substantially perpendicular to the recording paper transport direction. A motor to be driven, a driving belt (not shown), and the like are included. Note that the image forming unit 2 may form an image on a recording sheet by, for example, an electrophotographic method or a thermal transfer method.

  FIG. 2 shows the scanner unit 3. The scanner unit 3 is of a so-called flat bed type, and has a substantially rectangular document table 3a disposed on the upper surface of the scanner housing 12, and a side of the document table 3a in the front-rear direction of the image forming apparatus 1 ( A transmission plate 3b arranged in a strip shape so that the main scanning direction (arrow A direction in the figure) is the longitudinal direction. The document table 3a and the transmission plate 3b are made of, for example, a glass plate. The document table 3a and the transmission plate 3b of the scanner unit 3 are covered with a document cover 11 as shown in FIG. On the upper surface of the document cover 11, document positioning portions 29 are respectively provided at three positions on the document tray 28 at the rear, front, and side of the document transport position. As a result, both end portions and rear end portions in the transport direction of the document placed on the document tray 28 are positioned, and the ADF 20 is configured so as to be appropriate.

  An image reading unit 30 is housed inside the scanner housing 12. The image reading unit 30 includes, for example, a CIS (Contact Image Sensor) 31 and a drive mechanism 32 that moves the CIS 31 in a sub-scanning direction substantially orthogonal to the main scanning direction. For example, the CIS 31 is arranged so that the main scanning direction is a longitudinal direction so as to be in contact with the inner surfaces of the document table 3a and the transmission plate 3b, and images the surfaces of the document table 3a and the transmission plate 3b. The CIS 31 is arranged so as to be capable of reciprocating in the sub-scanning direction along the rail 32d with the position indicated by a two-dot chain line N in the figure as a home position where the surface of the transmission plate 3b can be imaged. The drive mechanism 32 is connected to the CIS 31 and arranged along the sub-scanning direction, a belt 32a arranged by the pulley 32b along the sub-scanning direction (arrow B direction in the figure), a motor 32c for driving the belt 32a, and the sub-scanning direction. It is comprised by the rail 32d etc. When reading an original using the ADF 20, the image reading unit 30 images the surface of the transmission plate 3b with the CIS 31 placed at the home position. On the other hand, when reading a document placed on the document table 3a, the surface of the document table 3a is imaged while the CIS 31 is moved below the document table 3a in the sub-scanning direction by driving the motor 32c of the drive mechanism 32. To do.

  FIG. 3 shows the scanner unit 3 with the document cover 11 open. A pad 11b is provided on the lower surface of the document cover 11 at a portion corresponding to the document table 3a. When the document cover 11 is closed, the document placed on the document table 3a is pressed against the document table 3a by the pad 11b. In this manner, the original is held by the pad 11b so that the position of the original on the original table 3a does not change, so that the original can be read properly.

  The ADF 20 includes a paper feed mechanism (not shown) that feeds the documents on the document tray 28 one by one, a transport roller 21 that rotates in the direction of the arrow in FIG. A motor (not shown) for driving the roller 21 and the like is included. As shown in the figure, the transport roller 21 is formed in a columnar shape, and one is provided at the approximate center of the transmission plate 3b in the main scanning direction. On both sides of the conveyance roller 21, a semi-cylindrical platen portion 22 having a slightly smaller radius than the conveyance roller 21 is provided. The platen unit 22 is substantially fixed to the document cover 11 so as to be movable up and down by a slight amount with respect to the document cover 11. When the document cover 11 is closed, the transport roller 21 and the platen unit 22 face the part imaged by the CIS 31 on the surface of the transmission plate 3b. At this time, the gaps between the transmission plate 3b, the transport roller 21, and the platen portion 22 are configured to open very little. In the present embodiment, the transport roller 21 and the platen unit 22 are made of a light color member such as white or light gray.

  As shown in FIG. 1, a conveyance port 20 a that is open so that a document can be inserted is provided at the lower part on the center side of the document tray 28 of the ADF 20. In addition, a discharge port 20 b that opens to the center side of the document tray 28 and has substantially the same width as that of the transfer port 20 a is provided above the transfer port 20 a of the ADF 20. In the present embodiment, the document is placed at a predetermined transport position on the document tray 28 such that one end of the document is inserted into the transport port 20a. The ADF 20 transports the document placed at the transport position that is in contact with the upper surface of the document cover 11 at the bottom in the transport direction indicated by the arrow F in the drawing. When the original is conveyed along the original conveyance path inside the ADF 20 to the surface of the transmission plate 3 b, the original is brought into close contact with the transmission plate 3 b along the conveyance roller 21 and the platen unit 22, and is read by the image reading unit 30. Then, the document is transported by the rotation of the transport roller 21, bent upward along the document transport path from the transmission plate 3 b, and reversed from the state where it is placed on the document tray 28. 20b is discharged onto the document cover 11.

  In the present embodiment, as shown in FIG. 3, an identification pattern 25 is provided in a portion of the platen unit 22 that faces the portion that the CIS 31 of the transmission plate 3 b reads when the document cover 11 is closed. Yes. In the present embodiment, the identification pattern 25 is a pattern in which, for example, a plurality of points are arranged on a substantially straight line along the main scanning direction. The identification pattern 25 includes not only achromatic colors such as black and gray but also a pattern having a plurality of chromatic colors such as red, blue, green, yellow, and mixed colors thereof. Compared with the member color of the portion 22, it is formed in a color that is easy to identify.

  FIG. 4 shows an operation flow of the control unit 9 when the image forming apparatus 1 performs image reading. The image forming apparatus 1 is configured to be able to read a document without providing, for example, a sheet presence / absence detection sensor of the document tray 28 or a sheet edge detection sensor of a document conveyed by the ADF 20. The document reading operation is started, for example, when the operation button 4 is operated by the user. When the document reading operation is started, the controller 9 first rotates the transport roller 21 while imaging the surface of the transmission plate 3b with the CIS 31 while the CIS 31 is stopped at the home position (S1). When the transport roller 21 is rotated, the control unit 9 temporarily stores the image data captured by the CIS 31 in, for example, a memory included in the control unit 9 and determines whether the image data changes from the one indicating the identification pattern 25. Is determined (S2). The controller 9 is configured to make this determination for a predetermined period after the rotation of the transport roller 21 is started at the longest. This predetermined period is set, for example, such that the rotation of the conveyance roller 21 is a period during which the original can be reliably conveyed to the transmission plate 3b when the original is fed from the original tray 28. Whether or not the predetermined period has elapsed is determined based on, for example, a step value of an encoder provided in the conveyance roller 21 or a motor that drives the conveyance roller 21.

  When the imaging data changes while the transport roller 21 is being rotated, the control unit 9 places the document on the document tray 28, the document is transported by the ADF 20, and the leading end of the document in the transport direction. Is determined to have reached the part imaged by the CIS 31 of the transmission plate 3b (S2: YES). In this case, the control unit 9 continues the imaging with the CIS 31 and the driving of the transport roller 21 of the ADF 20 (S13). Imaging by the CIS 31 is performed until the imaging data indicates the identification pattern 25 again. That is, the control unit 9 determines that the front end of the document in the conveyance direction is imaged when the imaging data of the CIS 31 is changed from the one indicating the identification pattern, and the imaging data becomes the one indicating the identification pattern 25 again. It is determined that the end of the document in the conveyance direction is captured. Then, the image data generated between the leading edge and the trailing edge of the document indicates the document, and image data is generated, thereby reading the document conveyed by the ADF 20. When the captured image data again indicates the identification pattern 25 and the end portion of the document in the conveyance direction is detected (S14: YES), the control unit 9 rotates the conveyance roller 21 for a predetermined period to discharge the document. Then, the document is discharged from the discharge port 20b, and the document is fed on the document tray 28 by the ADF 20 (S15). When the imaged data by the CIS 31 changes from that indicating the identification pattern 25, the control unit 9 determines that the second original has been conveyed (S16: YES), and reads the original in the same manner as described above. On the other hand, when the image pickup data of the CIS 31 does not change from that indicating the identification pattern 25 while the conveying roller 21 is rotated for a predetermined period after the end of the document is detected (14: YES) (S16: NO). Then, the control unit 9 stops the rotation of the conveying roller 21 (S17) and ends the document reading operation.

  On the other hand, when the imaging data does not change during a predetermined period during which the transport roller 21 is rotated, the control unit 9 determines that no document is placed on the document tray 28 (S2: NO), and the transport motor is turned on. The operation is stopped (S23), and the reading operation of the document on the document table 3a is performed (S24). That is, the control unit 9 moves the CIS 31 from the home position to the lower side of the document table 3a by the drive mechanism 32, and moves the CIS 31 while contacting the inner surface of the document table 3a as described above. When the reading of the document on the document table 3a is completed, the control unit 9 returns the CIS 31 to the home position and ends the document reading operation.

  As described above, in this embodiment, the presence / absence of a document is determined by a simple configuration in which the identification pattern 25 is read using the CIS 31 without providing a sensor for detecting the presence / absence of the document on the document tray 28 or the position of the document. By determining the position of the original, the original conveyed by the ADF 20 and the original on the original table 3a can be read, and the manufacturing cost of the image forming apparatus 1 can be reduced. In addition, since the identification pattern 25 has a plurality of points arranged in a substantially straight line in the main scanning direction and has a plurality of kinds of chromatic colors, the image data when the identification pattern 25 is imaged and the document are imaged. Can be reliably distinguished from each other, the edge of the document can be detected more reliably and the position of the document can be detected more reliably, and the document can be read more appropriately. Furthermore, when the image data of the CIS 31 does not change from the one indicating the identification pattern 25 while the transport roller 21 is rotated during document reading, the control unit 9 performs the document reading operation on the document table 3a. The image forming apparatus 1 can automatically determine whether to perform image reading using the ADF 20 or to read the document on the document table 3 a and read the document. It is possible to use the image forming apparatus 1 more conveniently while reducing the manufacturing cost of the image forming apparatus 1 with a simple configuration that does not require a sensor or the like for detection.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, the identification pattern 25 is not composed of a plurality of colored points as described above, and may have various colors, patterns, and the like. The scanner unit 3 may be configured to be able to read a document by a reading unit using an image sensor such as a CCD. Furthermore, the present invention can also be applied to a scanner device equipped with an ADF that does not have an image forming function.

1 is a perspective view illustrating an example of an image forming apparatus according to an embodiment of the present invention. The top view which shows the scanner housing | casing of the said apparatus. The perspective view which shows the said scanner part when an original cover is made into an open state. 6 is a flowchart showing a flow of scanner operation of the apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 3 Scanner part (scanner apparatus)
3a Document base 3b Transmission plate 9 Control unit 10 Printer casing 11 Document cover 12 Scanner casing 20 Auto document feeder 21 Conveying roller 25 Identification pattern 28 Document tray 30 Image reading unit

Claims (4)

An image is formed on a recording sheet on the basis of a scanner unit disposed above the printer casing and image data of a document or image data input from an external device that is disposed below the scanner unit and read by the scanner unit. An image forming unit; and a control unit that controls operations of the scanner unit and the image forming unit,
The scanner unit is
A scanner housing;
A substantially rectangular document table disposed on the upper surface of the scanner housing;
A transmission plate disposed in the vicinity of the side of the document table;
A document cover disposed in the scanner housing so as to be openable and closable so as to cover the document table and the transmission plate;
The document cover includes a transport roller for transporting the document, and the top surface of the document cover among the documents placed on the document tray on the top surface of the document cover by rotating the transport roller. Is transported to the transmitting plate and brought into contact with the upper surface of the transmitting plate, and the document transported to the transmitting plate is viewed from above the document placed on the document cover. An auto document feeder for discharging onto the document cover;
An image reading unit housed in the scanner housing and capable of capturing an image of the surface of the document table or the transmission plate;
The control unit performs a reading operation of a document conveyed by the auto document feeder by the image reading unit when a document is placed on the document tray during document reading, and the document is loaded on the document tray. In the image forming apparatus configured to scan the document reading unit on the document table by scanning the image reading unit in contact with the document table when the image reading unit is not placed.
A portion of the auto document feeder that is substantially fixed to the document cover and faces the transmission plate when the document cover is in a closed state can be imaged by the image reading unit via the transmission plate. An identification pattern in which a plurality of points are arranged on a substantially straight line in a direction substantially orthogonal to the document conveyance direction is provided,
The identification pattern has a plurality of types of chromatic colors,
The controller is
While reading a document, the image reading unit rotates the transport roller for a predetermined period while imaging the surface of the transmission plate,
When the image data of the image reading unit changes from the image obtained by imaging the identification pattern while the conveyance roller is rotated, the original is placed on the original tray and the original is conveyed. It is determined that the tip has reached the transmission plate, and imaging of the surface of the transmission plate is continued while rotating the conveyance roller until the imaging data of the image reading unit indicates the identification pattern,
When the image data of the image reading unit does not change from the image of the identification pattern while the transport roller is rotated, it is determined that no document is placed on the document tray, and the image reading unit Is configured to perform a reading operation of the document on the document table.
Accordingly, there is no need to provide the auto document feeder with a sensor for detecting that a document is placed on the document tray or a sensor for detecting the position of the document being conveyed, and the auto document feeder has a simple configuration. An image forming apparatus characterized in that reading of a document using a document and reading of a document on the document table can be executed. An image reading unit disposed on the back side of the transmission plate so as to image the surface of the transmission plate;
An auto document feeder that sequentially conveys the document placed on the document tray to the transmission plate by rotating a conveyance roller;
A scanner device including a control unit that controls the image reading unit and the auto document feeder and reads the document as image data;
Of the auto document feeder, a part facing the surface of the transmission plate is provided with an identification pattern that can be imaged by the image reading unit,
The controller is
While reading a document, the image reading unit rotates the transport roller for a predetermined period while imaging the surface of the transmission plate,
When the imaging data of the image reading unit changes from the imaged image of the identification pattern while rotating the transport roller, the imaging data of the image reading unit shows the identification pattern until the imaged data is displayed. A scanner device configured to continue imaging of the surface of the transmission plate while rotating a conveyance roller.   The scanner device according to claim 2, wherein the identification pattern has a plurality of types of chromatic colors. An original platen that is disposed near a side portion of the transmission plate and on which an original can be placed;
A document cover arranged to cover the document table and the transmission plate;
The auto document feeder is disposed on the document cover so as to correspond to the transmission plate,
The image reading unit is provided so as to be able to image the upper surface of the document table or the transmission plate,
When the image is read, when the image data of the image reading unit does not change from the image of the identification pattern while rotating the transport roller, the document is placed on the document tray. 4. The scanner device according to claim 2, wherein the scanner device is configured to perform the reading operation of the document on the document table by the image reading unit.

Images