JP2010087806A - Image reading apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus for reading a document while feeding the document, which generates excellent read image data by suppressing influences of change in reflection light quantity caused by a difference in curving modes of the document. <P>SOLUTION: The image reading apparatus starts feeding the document (S200) and feeds a reading unit synchronously to document feeding (S250) at a point of time when a leading portion of the document reaches a light quantity measurement starting position, so that a reading unit reads the leading portion of the document at all times. Namely, during feeding, the reading unit is caused to execute the reading operation over and over again (S260), thereby measuring the quantity of reflection light at the leading portion of the document at each of points on a feeding path of the reading unit (S270). The point where the reflection light quantity matches a predetermined FB light quantity setting value is then determined as an optimal reading position (S320) and while moving the reading unit backward to the determined optimal reading position, document reading is performed during moving. After the reading unit is completely moved backward, document reading is then performed at the optimal reading position (S390). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that conveys a document to be read and reads the document, and a program used in the image reading apparatus.

  2. Description of the Related Art Conventionally, as an image reading apparatus, an apparatus equipped with a document feeder (so-called ADF (Auto Document Feeder)) is known. In this type of image reading apparatus, generally, a document is conveyed in the sub-scanning direction with the reading unit fixed, and the document is read.

  Further, in this type of image reading apparatus, in order to solve the problem that the amount of reflected light changes due to the document being curved during document conveyance, the document is read while moving the reading unit, and the amount of reflected light at that time is determined. The position where the amount of reflected light is maximized is determined as the optimum position of the reading unit, and when the document is actually read, the reading unit is moved to the predetermined optimum position. In addition, there is known one that reads a document that is conveyed by fixing a reading unit at that position (see, for example, Patent Document 1).

The reason why the amount of reflected light changes due to the curvature of the document is that the propagation direction of reflected light varies depending on the curvature of the document, or the optical path length from the reading unit to the document position varies. .
JP-A-8-279881

  However, in the prior art, when the optimum position is determined in advance and the user gives a reading instruction, the document to be read is read at the optimum position previously determined. In the situation that changes every time, there is a problem that the original cannot be read at an appropriate position.

  That is, in the prior art, the actual position is not actually determined by measuring the amount of reflected light for the document that the user has instructed to read. There is a problem that even if the amount of reflected light changes due to differences in paper materials such as sheath and hardness (stiffness), the change cannot be accommodated.

  The present invention has been made in view of these problems, and in an image reading apparatus that reads a document while conveying the document, it is preferable to suppress the influence of a change in the amount of reflected light caused by a difference in the curved form of the document due to a difference in paper material. An object of the present invention is to enable generation of read image data.

  In order to achieve the above object, an image reading apparatus according to claim 1, wherein a document to be read is transferred from a paper feed unit that holds the document to be read to a paper discharge unit that holds the document after reading. A document conveying means that conveys the document by rotating the document, a reading unit that optically reads the document conveyed by the rotation of the roller at a position close to the roller in a main scanning direction parallel to the axis of the roller, and a reading unit. A unit transporting means for transporting in a sub-scanning direction orthogonal to the main scanning direction in a plane parallel to the roller axis (in other words, the direction of the projection component of the document transporting direction onto the plane by the document transporting means), and a document Control means for controlling the conveying means, the reading unit, and the unit conveying means to cause the reading unit to read the original to be read and to generate read image data representing the read image of the original; An image reading device to obtain, said control means, in which the following first to fourth steps are in the configuration for generating image data reading representing the read image of the document.

  The control unit causes the document conveying unit to convey the document to be read from the paper feeding unit, and when the leading end of the document reaches the stop position of the reading unit, the control unit moves the reading unit to the unit conveying unit. As the document moves in the sub-scanning direction, the reading unit causes the reading unit to perform a plurality of reading operations. Read in direction (first procedure).

  Further, based on each line image data representing the reading result in the main scanning direction generated by the reading unit by a plurality of reading operations in the first procedure, “the reading operation is performed by the first procedure in the conveyance path of the reading unit”. The amount of light input to the reading unit at each point in the “performed area” is specified, and a single point where the amount of light satisfies a predetermined condition in the sub-scanning direction is determined as the optimum position of the reading unit (second). Procedure).

  In addition, after the optimum position is determined, the reading unit has reached the optimum position by causing the unit conveying means to convey the reading unit back to the optimum position and causing the reading unit to read the original during the conveyance. The document front area, which is the area within the document up to the readable document position, is read by the reading unit, and the reading unit represents each reading result of the document front area as line image data constituting the read image data. Line image data is generated (third procedure).

  After reaching the optimum position of the reading unit, the reading unit is held at the optimum position, and the reading unit is caused to execute the reading operation at the optimum position, and the document conveying unit conveys the document to the paper discharge unit. As a result, the document rear area as the area in the document that continues from the document front area to the document conveyance direction rear is read by the reading unit, and the reading unit uses the reading unit as line image data constituting the read image data. Each line image data is generated (fourth procedure).

  According to the image reading apparatus configured as described above, the optimum position of the reading unit is determined every time the document is transported, and the document is read at the optimum position. Even if the bending mode of the document changes at, good read image data can be generated while suppressing the influence of the change in the amount of reflected light.

  The control means may be configured to determine a point where the light amount (reflected light amount) input to the reading unit is the maximum as the optimum position of the reading unit (Claim 5), or input to the reading unit. A point where the amount of light (the amount of reflected light) matches a predetermined reference value may be determined as the optimum position of the reading unit.

  If the point where the amount of reflected light is the maximum is determined as the optimum position of the reading unit, each original to be read can be always read with the maximum amount of light regardless of the curvature of the original. It can be suppressed that the image represented by becomes a dark image with low luminance.

  Further, if the point where the reflected light amount matches the reference value is determined as the optimum position of the reading unit, each original to be read can be read with the same light amount at all times, and the image represented by the read image data It is possible to suppress the brightness of each document from changing due to a difference in paper material or a wrinkle on the document.

  Further, the control means uses the line image data representing the reading result of the leading end portion of the document generated by the reading unit in the first procedure as the line image data constituting the read image data, and the line image data, The read image data is generated by a combination of each line image data of the document front area generated by the third procedure and each line image data of the document rear area generated by the fourth procedure. (Claim 2).

  That is, the document front area is an area excluding the front end portion of the document, and starts from a document position adjacent to the rear side in the transport direction of the front end portion of the document, and can be read when the reading unit reaches the optimum position. It may be determined as an area in the document whose position is the end point.

  If the image reading apparatus is configured in this way, the read image data representing the reading result of the entire original is generated using the line image data at the head of the original obtained at the time of measuring the amount of light, so the optimum position is determined. At this point, there is no need to read the leading edge of the document again, and the reading speed of the entire document is improved.

  In the third procedure, the document is conveyed in the forward direction while the reading unit is retracted to the optimum position, and the document is read by the reading unit while simultaneously performing the document conveyance and the conveyance of the reading unit. However, when the reading unit reads the document while simultaneously performing the document transport and the transport of the reading unit, the control of the document reading becomes complicated.

  Therefore, when the control unit causes the unit conveyance unit to convey the reading unit in the direction of retracting to the optimum position in the third procedure, the control unit first causes the document conveyance unit to temporarily stop the conveyance of the document. After the stop, the unit transporting unit is configured to transport the reading unit in the direction of retreating to the optimal position, and after the reading unit reaches the optimal position, the document transporting unit is configured to restart the transport of the document in the fourth procedure. (Claim 3).

  In this way, if the reading unit is retracted to the optimum position with the document conveyance stopped, the document is read by the reading unit while simultaneously performing the document conveyance and the conveyance of the reading unit. It is possible to avoid complicated reading control.

  In addition, during the period until the reading unit is moved to the optimum position, the amount of light input to the reading unit changes, so if no correction is made to the line image data obtained from the reading unit, it is input to the reading unit. There is a possibility that luminance unevenness corresponding to a change in the amount of light that appears in the read image data of the entire document.

  Therefore, the control means is based on the light quantity information at each point specified in the second procedure, in the period until the reading unit moves back to the optimum position among the line image data constituting the read image data. The luminance of each line image data generated by the read operation performed is determined according to the difference between the light amount at the point where the read operation corresponding to the line image data is performed and the light amount input to the reading unit at the optimum position. It is preferable that the read image data representing the read image of the document is generated using the corrected line image data.

  By configuring the image reading apparatus in this way, it is possible to suppress uneven brightness due to the difference in the amount of light in the read image data area corresponding to the area of the original read during the period until the reading unit is moved to the optimum position. can do.

  Further, like a flatbed type image reading apparatus equipped with an ADF, a transparent plate installed on the conveyance path of the reading unit in parallel with the roller axis and in the sub-scanning direction as the reading unit conveyance direction. And a document placing table on which the document to be read is placed, and the control means generates read image data for the document to be read placed on the document placing table. In the lower area of the document placed on the document placing table, the unit transporting means transports the reading unit in the sub-scanning direction, and causes the reading unit to perform a reading operation during the transport, thereby generating the reading unit. In an image reading apparatus configured to generate read image data representing a read image of a document formed by combining each line image data, an original placed on a document table is placed. The quantity of light input to the reading unit during the read image data generation for, with prescribed reference value, the control means may be configured as follows.

  That is, the control means generates read image data representing the read image of the original by the first to fourth procedures when generating the read image data for the original to be read held by the paper feed unit. The point where the amount of light input to the reading unit coincides with a predetermined reference value may be determined as the optimum position of the reading unit.

If the image reading apparatus is configured in this way, it is possible to suppress variations in brightness in the read image data between the flat bed reading and the ADF reading.
Further, the first to fourth procedures described above can be executed by a computer of an image reading apparatus including the above-described document conveying means, reading unit, and unit conveying means, according to a program (claim 8). .

  A program for causing a computer to execute the above first to fourth procedures can be provided by being recorded on various recording media such as a CD-ROM and a semiconductor memory.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating an electrical configuration of the image reading apparatus 1 of the present embodiment. The image reading apparatus 1 mainly includes a control unit 10, a reading unit 21, a carriage transport mechanism 30, an ADF (original transport device) 40, a display operation unit 50, and an interface 60.

  The control unit 10 includes a CPU 11, a ROM 13, and a RAM 15, and performs overall control of the entire apparatus by causing the CPU 11 to execute a program stored in the ROM 13.

  On the other hand, the reading unit 21 is an optical image sensor configured as a CIS (contact image sensor), and is configured to be able to read an image of N lines in the main scanning direction. The value N is an integer of 1 or more determined by the image sensor to be used. In the present embodiment, the discussion proceeds assuming that N = 1.

  The reading unit 21 has a built-in light source (not shown) and has a configuration in which light receiving elements for each pixel are arranged in the line direction. By receiving light by the light receiving element, line image data in which the luminance values of the respective pixels corresponding to the amount of received light are arranged is generated and output for each line.

  In this way, the reading unit 21 reads the reading target located in the emission direction of the light source, and inputs each line image data representing the reading result to the control unit 10. Note that the reading unit 21 performs a reading operation under the control of the control unit 10.

  The carriage transport mechanism 30 includes a motor MT1 for transporting a carriage 31 (see FIG. 2) on which the reading unit 21 is mounted and a sensor SN1 for detecting the position of the carriage 31, and the carriage MT is driven by the driving force of the motor MT1. 31 is transported in the sub-scanning direction orthogonal to the main scanning direction.

  The detection signal of the sensor SN1 is input to the control unit 10, and the motor MT1 is controlled by the operation of the control unit 10 based on the detection signal of the sensor SN1. That is, the carriage transport mechanism 30 is controlled by the control unit 10 to transport the carriage 31 in the sub-scanning direction.

  The ADF 40 includes a plurality of types of rollers, which will be described later. By rotating these rollers, the document to be read placed on the document tray 41 is transported to a reading position by the reading unit 21. The paper is discharged to the paper discharge tray 42.

  Specifically, the ADF 40 includes a motor MT2 for rotating the roller and a plurality of sensors SN2 for detecting the document position. A detection signal of the sensor SN2 is input to the control unit 10.

  That is, the motor MT2 is controlled by the operation of the control unit 10 based on the detection signal of the sensor SN2. In other words, the ADF 40 is controlled by the control unit 10 to convey a document to be read.

  The display operation unit 50 includes a liquid crystal monitor for displaying various information and various operation keys that can be operated by the user, and functions as a user interface. In addition, the interface 60 is configured to be able to communicate with the external device 100, and for example, transmits data to be transmitted input from the control unit 10 to the external device 100.

  Next, detailed configurations of the carriage transport mechanism 30 and the ADF 40 will be described with reference to FIG. FIG. 2A is a schematic cross-sectional view of the image reading apparatus 1 showing the configurations of the carriage transport mechanism 30 and the ADF 40.

  The image reading apparatus 1 has a configuration in which a cover 80 containing an ADF 40 is provided above the apparatus main body 70 so as to be openable and closable with respect to the apparatus main body 70, as in a known apparatus. FIG. 2B is a schematic cross-sectional view illustrating the configuration of the image reading apparatus 1 in a state where the cover 80 is opened with respect to the apparatus main body 70. With respect to the apparatus main body 70, a portion indicated by a dotted line in FIG.

  The carriage transport mechanism 30 is provided in a hollow rectangular parallelepiped casing 71 that forms the outer edge of the apparatus main body 70. Specifically, the carriage transport mechanism 30 includes a motor 31 and a sensor SN1, a carriage 31, and a guide shaft 33 that forms a transport path of the carriage 31.

  The casing 71 has a configuration in which an upper surface is opened, and a transparent platen glass 73 is attached to the opening. That is, the apparatus main body 70 is configured such that the opening provided on the upper surface of the casing 71 is closed by the platen glass 73.

  The guide shaft 33 is provided along the longitudinal direction of the casing 71 in parallel with the platen glass 73 in the casing 71 having such a configuration. Specifically, the guide shaft 33 is provided in the casing 71 so that the carriage 31 can move in the entire area under the platen glass along the longitudinal direction of the casing 71. ing.

  The carriage 31 is slidably provided on the guide shaft 33 and moves below the platen glass 73 along the guide shaft 33 in response to the driving force of the motor MT1. That is, the above-described sub-scanning direction corresponds to the longitudinal direction of the casing 71 from which the guide shaft 33 extends.

  Further, the reading unit 21 is mounted on the carriage 31 so that the light receiving elements are arranged in a direction (main scanning direction) perpendicular to the guide shaft 33 on a plane parallel to the platen glass 73.

  In FIG. 2, the power transmission system from the motor MT1 to the carriage 31 is not shown, but the driving force of the motor MT1 is transmitted to the carriage 31 via an endless belt, for example.

  A pulley attached to the rotation shaft of the motor MT1 is provided on one end side of the guide shaft 33, and a pulley that is paired with the pulley is provided on the other end side of the guide shaft 33. A belt is wound, the carriage 31 is connected to the endless belt, and when the motor MT1 rotates, the carriage 31 moves in the sub-scanning direction due to the rotation of the endless belt that rotates following the pulley. .

  The cover 80 is shaped to cover the platen glass 73 of the apparatus main body 70 while being closed with respect to the apparatus main body 70. The ADF 40 built in the cover 80 is provided above the ADF reading region R <b> 2 (see FIG. 3) in the platen glass 73 constituting the apparatus main body 70.

  FIG. 3 is an explanatory diagram showing the relationship between the regions R1 to R3 of the platen glass 73 partitioned by the partition plates 75 and 76. FIG. As shown in FIG. 3, partition plates 75 and 76 extending in the main scanning direction are provided on the platen glass 73. The partition plates 75 and 76 allow the platen glass 73 to be in the home position region R1 and the ADF reading region. R2 and FB (flatbed) reading area R3 are partitioned.

Here, the home position region R <b> 1 is covered with the white reference member 79. The white reference member 79 is used to obtain parameters necessary for shading correction.
The FB reading area R3 functions as a document placement table. At the time of FB reading, the control unit 10 reads the document P placed in the FB reading region R3 by conveying the carriage 31 in the sub-scanning direction under the FB reading region R3, and represents the reading result of the document. Read image data is generated.

  On the other hand, the ADF reading area R <b> 2 is an area for reading a document conveyed by the ADF 40. At the time of ADF reading, the control unit 10 arranges the carriage 31 (and thus the reading unit 21) below the ADF reading region R2, reads the original conveyed by the ADF 40, and represents the reading result of the original. Read image data is generated.

In other words, the ADF 40 is provided above the ADF reading region R2 so that the document P can be conveyed.
Specifically, the ADF 40 includes a document tray 41 on which the document P to be read is placed and a paper discharge tray 42 on which the document P after being read by the reading unit 21 is placed, and is stacked on the document tray 41. A separation mechanism 43 that separates documents one by one, a transport mechanism 45 that transports the documents separated by the separation mechanism 43 to the ADF reading region R2 while turning, and a document transported by the transport mechanism 45 A document presser 47 for pressing to the reading area R2 side and a paper discharge mechanism 49 for transporting the document sent to the ADF reading area R2 to the paper discharge tray 42 are provided.

  The separation mechanism 43 takes out the documents P stacked on the document tray 41 one by one and feeds them to the separation roller 433, and the separation roller 433 that applies a conveyance force to the document P conveyed from the suction roller 431. , And pads 435, 436, etc., which are disposed opposite to the suction roller 431 and the separation roller 433 and give a conveyance resistance to the document P.

  On the other hand, the transport mechanism 45 applies a transport force while turning the transport direction of the document P transported from the separation mechanism 43 to the ADF reading region R2 side, and the document P to the feed roller 451. It consists of a pair of pinch rollers 453, 455 and the like to be pressed.

  The document presser 47 is provided above the ADF reading region R2 in order to press the document P conveyed from the transport mechanism 45 toward the ADF reading region R2. Since the document P travels obliquely downward from the paper feed roller 451 to the ADF reading region R2, the document pressing unit 47 has a pressing plate 471 that is inclined downward from the upstream side to the downstream side in the document conveying direction. It is attached.

  The paper discharge mechanism 49 includes a conveyance roller 491, a pinch roller 493, and the like. The document P conveyed from the ADF reading region R2 is sandwiched between the conveyance roller 491 and the pinch roller 493. The original P is discharged to the paper discharge tray 42.

  Each roller included in the ADF 40 including the paper feed roller 451 has an axis parallel to the main scanning direction, and rotates by receiving the driving force of the motor MT2, so that the document P is moved in the main scanning direction. Are conveyed from the document tray 41 to the paper discharge tray 42 in the orthogonal direction.

  By the way, in the image reading apparatus 1 of this embodiment, the document P is guided to the ADF reading region R2 so that the document P is warped by the paper feed roller 451. Therefore, the document is located around the ADF reading region R2 with the document pressing 47 as a base point. Curved in a U-shape (see FIG. 7D). In other words, the orientation of the document P changes from obliquely downward to obliquely upward with the document retainer 47 as a boundary.

  Further, the curvature of the document P with the document presser 47 as a base point is a factor such as whether or not the document P on the document tray 41 is wrinkled, and the paper thickness such as thickness and hardness (stiffness) of the document P. It changes depending on the material.

  Further, due to the difference in curvature, even in the ADF reading region R2, the reading unit 21 is always arranged at a fixed position, and even when the document P is read at this position, the amount of light (reflected from the light source and input to the light receiving element) The amount of reflected light changes for each document P. If the amount of reflected light is weak, there arises a problem that, for example, a read image of a document becomes a dark image.

  Therefore, in the image reading apparatus 1 of the present embodiment, when reading the document P using the ADF 40, the optimum reading position of the reading unit 21 in the ADF reading region R2 is obtained for each document P, and the optimum reading position is obtained. The document P is read. This function is realized by the control unit 10 controlling the carriage transport mechanism 30 and the ADF 40.

  Hereinafter, a series of processes executed by the control unit 10 in order to realize an image reading function including this function will be described. FIG. 4 is a flowchart showing the main reading control process executed by the CPU 11 by the control unit 10. The control unit 10 repeatedly executes this reading main control process immediately after the image reading apparatus 1 is turned on.

  When the reading main control process is started, the control unit 10 first waits until a reading command is input (S110). The reading command is input through the display operation unit 50. When a reading command is input (Yes in S110), the process proceeds to S120, and it is determined whether or not the document P is placed on the ADF 40.

  A sensor for detecting whether or not the document P is placed on the document tray 41 is provided around the document tray 41. In S120, the document is placed on the ADF 40 based on the detection signal of the sensor. It is determined whether it is placed.

  If it is determined that the document is not placed on the ADF 40 (No in S120), the control unit 10 proceeds to S130 and considers that the document P to be read is placed in the FB reading region R3. Then, the FB reading control process is executed. Then, after the end of the FB reading control process, the reading main control process is temporarily ended, and the process waits until the next reading command is input (S110).

  Specifically, in the FB reading control process, initial processing such as obtaining parameters necessary for document reading is performed in a state where the reading unit 21 is disposed in the home position region R1. That is, by causing the reading unit 21 in the home position region R1 to perform a reading operation, the white reference member 79 is read by the reading unit 21, and light is received from the line image data obtained by reading the white reference member 79. Initial processing such as obtaining a shading correction parameter for correcting luminance unevenness due to a difference in element sensitivity or the like is performed.

  After the initial processing, the carriage 31 is transported in the positive direction of the sub-scanning direction (the direction away from the home position region R1) through the carriage transport mechanism 30, and the carriage 31 is located below the document P placement region in the FB reading region R3. , The reading unit 21 reads the document placed in the FB reading region R3 by causing the reading unit 21 to perform a reading operation at regular time intervals while conveying the image at a constant speed in the sub-scanning direction. Read image data representing a read image of the original P formed by combining the line image data generated by the reading operation is generated in the RAM 15. Then, after reading the document, the reading unit 21 is moved to the home position region R1.

  The read image data generated in the RAM 15 in this manner is output to the external device 100 after image correction such as shading correction is separately performed in an image output process executed by the control unit 10 separately. Examples of the external device 100 include a printing device, a personal computer, and a file server.

  On the other hand, if it is determined in S120 that the document P is placed on the ADF 40 (Yes in S120), the control unit 10 proceeds to S140 and executes the ADF reading control process shown in FIG. Then, one sheet of the document P to be read is taken out from the document tray 41, conveyed to the ADF 40, and further read through the reading unit 21 in the ADF reading area R2, and the read image of the document P is read. Represented read image data is generated in the RAM 15 (details will be described later).

  When the ADF reading control process is completed, it is determined whether or not the next document is placed on the document tray 41 (S150). If the next document is placed (Yes in S150), the process proceeds to S140. The ADF reading control process is executed again for the next original. That is, the control unit 10 executes ADF reading control processing for each original until there is no original placed on the original tray 41 and generates read image data of each original in the RAM 15.

  Then, by executing the ADF reading control process for all the documents placed on the document tray 41, when there are no more documents in the document tray 41, it is determined No in S150, and the reading main control process is temporarily ended. Wait until the next reading command is input.

  The read image data for each document generated in the RAM 15 in this way is subjected to image correction such as shading correction in an image output process separately executed by the control unit 10 as in the FB reading control process. It is output to the external device 100.

  Next, the ADF reading control process executed by the control unit 10 for each original in S140 will be described. FIG. 5 is a flowchart illustrating an ADF reading control process executed by the control unit 10.

  When the ADF reading control process is started, the control unit 10 performs an initial process such as obtaining parameters necessary for document reading in a state where the reading unit 21 is disposed in the home position region R1 (S210). Specifically, similar to the FB reading control process, a process such as obtaining a parameter for shading correction is performed. Note that when reading a plurality of documents P placed on the document tray 41 by a read command, the initial processing of S210 is appropriately omitted when the ADF reading control process is performed on the second and subsequent documents P. Can do.

  When the processing in S210 is completed, the control unit 10 proceeds to S220, takes out one document P placed on the document tray 41 from the document tray 41 through the ADF 40, and conveys it to the paper discharge tray 42. The document transport process to be started is started.

  Further, simultaneously with the start of the document conveying process, the carriage 31 is conveyed through the carriage conveying mechanism 30 to a predetermined light quantity measurement start position (see FIG. 3), and the carriage 31 (reading unit 21) is moved at the light quantity measurement start position. Wait (S230). The light quantity measurement start position is set in advance near the edge on the home position area R1 side in the ADF reading area R2.

  Further, after the process of S230, whether or not the leading end portion of the document P that has been transported in S220 has reached the light amount measurement start position (reading position of the reading unit 21) is input from the sensor SN2 of the ADF 40. A determination is made based on the detection signal (S240). For example, it is determined whether or not the front end of the document has reached the light measurement start position based on the elapsed time after the front end of the document is detected by a sensor provided in front of the light measurement start position.

  If it is determined that the front end of the document has not reached the light quantity measurement start position (No in S240), the control unit 10 stands by until the front end of the document reaches the light quantity measurement start position (S240). In the present embodiment, it is assumed that the front end of the document reaches the light quantity measurement start position after the carriage 31 (reading unit 21) has reached the light quantity measurement start position. FIG. 7A is an explanatory diagram showing the positional relationship between the document leading edge and the carriage 31 when the document leading edge reaches the light quantity measurement start position.

  If it is determined that the leading edge of the document has reached the light quantity measurement start position (Yes in S240), the control unit 10 proceeds to S250, and starts the synchronous conveyance process of the carriage 31 while continuing the document conveyance process.

  In this synchronous conveyance process, the conveyance position of the carriage 31 is controlled so that the carriage 31 is moved in the positive direction of the sub-scanning direction in synchronization with the movement of the original P, so that the reading position of the reading unit 21 is the original. It is always set to the same position with respect to P (document leading edge).

  In addition, the control unit 10 starts a document reading process that causes the reading unit 21 to repeatedly execute a reading operation at a constant time interval T0 along with the start of the synchronous conveyance process (S260). The time interval T0 is set to a value corresponding to the reading resolution.

  The control unit 10 starts the light quantity recording process shown in FIG. 6A together with the start of the document reading process (S260). With the start of the document reading process, the reading unit 21 performs a reading operation at a constant time interval T0, and line image data representing a reading result is input to the control unit 10 from the reading unit 21 at a constant time interval T0. However, the control unit 10 processes the line image data by a light amount recording process.

FIG. 6A is a flowchart showing a light amount recording process executed by the control unit 10.
When the light quantity recording process is started, the control unit 10 waits until the line image data generated by the reading operation at the light quantity measurement start position is input from the reading unit 21, and when the line image data is input, A pixel having the maximum luminance is searched from the line image data, and the pixel having the maximum luminance is determined as the light quantity measurement pixel (S510).

  Further, the luminance value of the light quantity measurement pixel determined in S510 is recorded in the RAM 15 as the reflected light quantity at the light quantity measurement start position in association with the information on the light quantity measurement start position (S520). At this time, the line image data is recorded in the RAM 15 as preliminary data in association with the information on the light quantity measurement start position, along with the recording of the reflected light quantity in the RAM 15.

  After this processing, the process proceeds to S530, where it is determined whether or not the next line image data has been input from the reading unit 21, and if the next line image data has not been input (No in S530), It is determined whether an end instruction has been input (S540).

If it is determined that the end instruction has not been input (No in S540), the process proceeds to S530 and waits until the next line image data is input or the end instruction is input (S530, S540).
When the next line image data is input (Yes in S530), the reading operation that causes the line image data to be generated using the luminance value of the light amount measurement pixel in the line image data as information on the reflected light amount. It is recorded in the RAM 15 in association with the position information of the carriage 31 at the time. Also at this time, the control unit 10 records the line image data in the RAM 15 as preliminary data in association with the position information of the carriage 31 during the reading operation. Thereafter, the process proceeds to S530.

  In this way, every time line image data is input from the reading unit 21, the control unit 10 associates the reflected light amount specified by the above-described method from the line image data with the position information of the carriage 31. The light amount measurement data recorded in the RAM 15 and associated with the reflected light amount and the carriage position as shown in FIG. 6B is generated in the RAM 15. FIG. 6B is an explanatory diagram showing light quantity measurement data generated in the RAM 15.

When an end instruction is input (Yes in S540), the control unit 10 ends the light amount recording process.
In this way, the control unit 10 performs light quantity measurement while controlling the carriage transport mechanism 30 and the ADF 40 so that the reading position of the reading unit 21 is always the same position (original document front end) with respect to the original.

  Further, after the light quantity recording process in S270 is started, the process proceeds to S280, and it is determined whether or not the latest reflected light quantity recorded in the RAM 15 by the light quantity recording process is larger than the FB light quantity set value stored in the ROM 13 in advance. (S280).

  Note that the FB light amount setting value is the reflected light amount when the original placed on the FB reading region R3 is read by the lower reading unit 21 in the FB reading control process (the luminance of the pixel when the original is a blank sheet). Value) is obtained in advance. This FB light quantity setting value is recorded in the ROM 13 at the design stage.

  If it is determined that the latest reflected light amount recorded in the RAM 15 is equal to or less than the FB light amount setting value (No in S280), the control unit 10 determines whether or not the carriage 31 has reached the light amount measurement end position. (S290) If it is determined that the carriage 31 has not reached the light quantity measurement end position (No in S290), the process proceeds to S280.

  In this manner, in S280 and S290, the process waits until the latest reflected light amount recorded in the RAM 15 becomes a value larger than the FB light amount set value or the carriage 31 reaches the light amount measurement end position.

Here, how the reflected light amount changes in the RAM 15 by the light amount recording process will be described with reference to FIGS.
FIG. 7B is an explanatory diagram showing the positional relationship between the leading end of the document and the carriage 31 at a point in time advanced by a predetermined time from the point shown in FIG. Here, the light quantity measurement start position is defined as a position PA, and as shown in FIG. 7B, the position of the carriage 31 at a time point advanced by a predetermined time from the time point illustrated in FIG. 7A is defined as a position PB.

  FIG. 7C is an explanatory diagram showing the positional relationship between the leading end of the document and the carriage 31 at a time further advanced from the time shown in FIG. 7B, and FIG. FIG. 8 is an explanatory diagram showing the positional relationship between the leading edge of the document and the carriage 31 at a time further advanced by a predetermined time from the time shown in FIG. Here, as shown in FIG. 7 (c), the position of the carriage 31 at a time point advanced by a predetermined time from the time shown in FIG. 7 (b) is defined as a position PC, and as shown in FIG. The position of the carriage 31 at a time point advanced by a predetermined time from the time point shown in FIG.

  As can be understood by comparing FIGS. 7A to 7D, in this example, when the carriage 31 reaches the position PC, the document P and the reading unit 21 are closest to each other. That is, in the process of moving from the position PB to the position PC, the document P and the reading unit 21 that are gradually approaching gradually move away when the carriage 31 moves from the position PC to the position PD.

  Therefore, when the reflected light amount up to the position PD is recorded in the RAM 15 by the light amount recording process, the relationship between the position of the carriage 31 indicated by the light amount measurement data and the reflected light amount is a function shape having a maximum point as shown in FIG. become. FIG. 8 is a graph showing the relationship between the position of the carriage 31 and the amount of reflected light.

  In S280 and S290, the latest value of the reflected light amount that changes in this way is compared with the FB light amount setting value, and if the reflected light amount exceeds the FB light amount setting value in the process of moving the carriage 31 from the position PA, at that point. It is determined Yes in S280, and the process proceeds to S300.

  In S300, the document conveyance process started in S220 is temporarily interrupted, the document P is temporarily stopped, the synchronous conveyance process started in S250 is terminated, the carriage 31 is temporarily stopped, and further the light quantity recording is performed. An end instruction is input to the process, and the above-described light quantity recording process is ended (S310). Thereafter, the control unit 10 proceeds to S320.

  On the other hand, when the maximum value of the reflected light amount is equal to or less than the FB light amount setting value, the control unit 10 measures the light amount until the carriage 31 reaches the light amount measurement end position without determining Yes in S280, and in S290. After determining Yes, the processing of S300 to S310 is executed. Thereafter, the control unit 10 proceeds to S320.

  In S320, the control unit 10 determines the optimum reading position of the document by the reading unit 21 based on the light amount measurement data recorded in the RAM 15. Here, the method for determining the optimum reading position will be described in detail. The method for determining the optimum reading position differs depending on whether it is determined to be Yes in S280 or if it is determined to be Yes in S290. I will explain.

  First, a case will be described where the reflected light amount does not take a value larger than the FB light amount setting value and the carriage 31 has reached the light amount measurement end position and it is determined Yes in S290. In this case, the position of the carriage 31 at the time when the reflected light amount becomes maximum is specified from the light amount measurement data stored in the RAM 15, and the position of the carriage 31 at the time when the reflected light amount becomes maximum is read. The optimum position is determined (S320).

  On the other hand, if the amount of reflected light is larger than the FB light amount setting value, and it is determined Yes in S280, the time is 1 as compared with the time when the reflected light amount becomes larger than the FB light amount setting value. At the previous time, the position of the carriage 31 associated with the reflected light amount written in the RAM 15 is regarded as a point where the reflected light amount matches the FB light amount setting value, and is determined as the optimum reading position (S320).

  When the optimum reading position is determined in this way, the control unit 10 proceeds to S330, and in the course of the reading operation related to the light amount measurement so far, the line data stored in the RAM 15 as the preliminary data is included. Then, the line image data generated by the reading operation at the determined optimum reading position is recorded in the read image data generation area of the RAM 15 as line image data of the leading end of the document constituting the read image data of the document. Further, the other spare data is deleted from the RAM 15.

  If the processing in S330 is suppressed, the control unit 10 proceeds to S340 and transports the carriage 31 through the carriage transport mechanism 30 in the negative direction of the sub-scanning direction (reverse direction) to the determined optimum reading position. Thus, the backward conveyance process for stopping the carriage 31 at the optimum reading position is started. At this time, the carriage 31 is conveyed in the negative direction of the sub-scanning direction at a speed V0 corresponding to the reading resolution of the original P.

Further, in accordance with the start of the backward conveyance process, the control unit 10 starts a document reading process that causes the reading unit 21 to repeatedly execute a reading operation at a constant time interval T0 (S350).
In this way, the control unit 10 causes the reading unit 21 to read the original by repeatedly performing the reading operation at the time interval T0 until the carriage 31 moves to the optimum reading position. Line image data of each line corresponding to a predetermined reading resolution, which can be read when the reading unit 21 reaches the optimal reading position from the original position adjacent to the rear side of the original document in the original conveying direction. The reading unit 21 is caused to generate each line image data of the document front area up to the correct document position.

FIG. 9 is an explanatory diagram showing the operation mode of the image reading apparatus 1 after the optimum reading position is determined until the carriage 31 is arranged at the optimum reading position.
In addition, after the above process is started in S350, the process proceeds to S360, and for each line image data sequentially output from the reading unit 21, the line image is output for the period until the reading unit 21 reaches the optimum reading position. Correction corresponding to the amount of reflected light at the execution point (reading position) of the reading operation that caused the data generation is performed, and the corrected line image data is used as line image data constituting the read image data of the document. And recorded in the read image data generation area of the RAM 15.

Specifically, based on the reflected light amount Qn at the position Dn where the carriage 31 was present when the reading operation that caused the generation of the correction target line image data is performed, and the reflected light amount Q0 at the optimum reading position. The luminance value X of each pixel of the line image data to be corrected is expressed by the following equation: Y = X · (Q0 / Qn)
Is converted into a luminance value Y. In this way, the line image data to be corrected is corrected, and corrected line image data is generated.

  The reflected light quantity Qn and the reflected light quantity Q0 are specified from the light quantity measurement data recorded in the RAM 15. That is, the reflected light quantity Q0 is set to the reflected light quantity associated with the optimum reading position in the RAM 15 (light quantity measurement data).

  The reflected light quantity Qn is set to the reflected light quantity associated with the position Dn in the light quantity measurement data stored in the RAM 15. However, if the reflected light quantity Qn associated with the position Dn is not recorded as light quantity measurement data in the RAM 15, the light quantity measurement data recorded in the RAM 15 is interpolated (for example, linear interpolation) to correspond to the position Dn. The amount of reflected light Qn to be specified is specified.

  In S360, the luminance of each line image data generated by the reading unit 21 in the process of moving the carriage 31 to the optimum reading position in this way is corrected according to the amount of reflected light, and the corrected line image data is Write in the read image data generation area. By this operation, each line image data of the document front area in consideration of the amount of reflected light at the time of the reading operation is recorded in the read image data generation area of the RAM 15.

When the reading unit 21 reaches the optimum reading position and stops at the optimum reading position, the control unit 10 determines Yes in S370 and proceeds to S380.
In step S380, the document conveyance process stopped by the ADF 40 is started by resuming the document conveyance process interrupted in step S300. In the document conveyance process after the restart, the document P is transferred to the paper discharge tray 42 at the same speed V0 as the speed V0 of the carriage 31 in the backward conveyance process with the reading unit 21 fixed at the optimum reading position. And carry. In this way, the relative speed between the reading unit 21 and the original P is matched with that during the backward conveyance process.

When the document transport process is resumed, a document reading process for causing the reading unit 21 to repeatedly execute a reading operation at a constant time interval T0 is started (S390).
That is, the control unit 10 causes the reading unit 21 to perform a reading operation at a constant time interval T0 while transporting the document P at a speed V0 while the reading unit 21 is fixed at the optimum reading position, so The reading unit 21 reads the document rear area that continues from the rear of the document P in the conveyance direction to the reading optimum position, and causes the reading unit 21 to generate each line image data of the document rear area.

  Further, after the start of the above-described processing in S390, the process proceeds to S400, and is sequentially output from the reading unit 21 until the writing of the line image data up to the last line of the original to the read image data generation area is completed. Each line image data in the document rear area is recorded in the read image data generation area of the RAM 15.

  When writing to the last line of the document is completed and read image data including a group of line image data from the first line to the last line is completed, it is determined Yes in S410, and the document is discharged to the ADF 40. After discharging to the tray 42 (S420), the ADF reading control process is terminated.

  When the ADF reading control process is completed in this manner, the RAM 15 stores a line generated as a read image data representing a read image of the original as shown in FIG. The document front area G2 following the document leading edge G1 is composed of line image data generated when the reading unit 21 is retracted to the optimum reading position, and the document rear area G3 is the optimum reading position of the reading unit 21. Read image data composed of line image data generated after being fixed to is generated.

  The image reading apparatus 1 according to the present embodiment has been described above. According to the image reading apparatus 1, the optimum reading position of the reading unit 21 is determined every time the document P is conveyed, and the document is read at the optimum reading position. Since P is read, even if the bending mode of the document P around the document presser 47 changes due to a difference in paper material or the like, it is possible to suppress the influence of the change in the amount of reflected light and generate good read image data. Can do.

  In particular, according to the image reading apparatus 1 of the present embodiment, a point where the light amount (reflected light amount) input to the reading unit 21 matches the predetermined FB light amount setting value is set as the optimum reading position of the reading unit 21. Therefore, it is possible to always read each original to be read with the same amount of light regardless of whether it is FB reading or ADF reading. It is possible to suppress changes from document to document due to reasons such as wrinkles on the document and differences in reading methods such as FB reading or ADF reading.

  Even if the position corresponding to the FB light amount setting value is the reflected light amount is not in the ADF reading region R2, the point where the light amount is maximum is determined as the optimum reading position, so that the read image data of the document is prevented from becoming dark. Therefore, it is possible to suppress the influence of the change in the amount of reflected light due to the curvature of the original and to generate good read image data.

  More specifically, the image reading apparatus 1 according to the present embodiment generates line image data of the leading end of the document as line image data constituting the read image data of the document while measuring the light amount. Then, line image data of the front area of the document is generated while adjusting the reading unit 21 to the optimum reading position. Therefore, according to the present embodiment, it is possible to efficiently generate read image data for one original while adjusting the reading position of the reading unit 21 for each original, and the reading speed of each original can be increased. Deterioration can be avoided.

  Further, according to the image reading apparatus 1 of the present embodiment, when the reading unit 21 is retracted to the optimum reading position, the reading unit 21 is stopped in a state where the conveyance of the document P is temporarily stopped and the document P is stopped. Since the reading operation of the document area (document front area) until reaching the optimum reading position is controlled, the control in this area is not complicated. That is, it is possible to avoid complicated document reading control as in the case where the reading unit 21 reads the document while simultaneously performing the document conveyance and the conveyance of the reading unit 21.

  In addition, according to the image reading apparatus 1 of the present embodiment, the line image data generated by the reading unit 21 when the reading unit 21 is moved back to the optimum reading position has its luminance adjusted to the reflected light amount. Since the read image data of the original is corrected, the luminance unevenness due to the difference in the amount of reflected light is added to the area of the read image data corresponding to the area of the original read during the period until the reading unit 21 is moved to the optimum reading position. Can be suppressed.

  The document conveying means described in “Claims” corresponds to the ADF 40 of the present embodiment, the paper feeding unit corresponds to the document tray 41, and the paper discharging unit corresponds to the paper discharging tray 42. The unit conveying means corresponds to the carriage conveying mechanism 30, and the control means corresponds to the control unit 10.

  In addition, the first procedure is realized by the processing of S220 to S260 executed by the control unit 10 in the CPU 11, the second procedure is realized by the processing of S270 to S320, and the third procedure is S340, The fourth procedure is realized by the processes of S380 and S390. The document placement table corresponds to the FB reading region R3 of the platen glass 73, and the reference value corresponds to the FB light amount setting value.

Further, the present invention is not limited to the above-described embodiments, and can take various forms.
For example, in the ADF reading control process, the optimum reading position may always be determined as the position where the amount of reflected light is maximized. In this case, since the determination in S280 is not necessary, the ADF reading control process may be configured to omit the step of S280. That is, in the ADF reading control process shown in FIG. 5, the ADF reading control process may be changed to a processing procedure equivalent to always determining No in S280.

  Further, S280 may be replaced with a step of determining whether or not the amount of reflected light has passed the maximum point. As shown in FIG. 8, the reflected light amount obtained by the light amount measurement gradually increases with the movement of the carriage 31 in the initial stage, but starts to decrease at a certain point.

Accordingly, in S280, the ADF reading control process may be configured such that when the amount of reflected light starts to decrease, the determination is Yes and the processes after S300 are executed.
As described above, when the ADF reading control process is configured and the point where the amount of reflected light is maximum is determined as the optimum reading position of the reading unit 21, each original to be read is always read regardless of the bending state of the original. It can be read with the maximum amount of light, and it can be suppressed that the image represented by the read image data becomes a dark image with low luminance.

2 is a block diagram illustrating an electrical configuration of the image reading apparatus 1. FIG. 2 is a schematic cross-sectional view of the image reading apparatus 1 showing the configurations of a carriage transport mechanism 30 and an ADF 40. FIG. It is a figure showing each area | region R1-R3 on the platen glass 73. FIG. 4 is a flowchart showing a reading main control process executed by a control unit 10. 4 is a flowchart showing an ADF reading control process executed by a control unit 10. It is the flowchart (a) showing the light quantity recording process which the control part 10 performs, and the block diagram (b) of the light quantity measurement data produced | generated by this process. FIG. 6 is an explanatory diagram showing a bending mode associated with conveyance of a document P. 4 is a graph showing the relationship between the position of a carriage 31 and the amount of reflected light. FIG. 6 is an explanatory diagram illustrating an operation mode of the image reading apparatus 1 from when the optimum reading position is determined until the carriage 31 is arranged at the optimum reading position. It is explanatory drawing showing the structure of read image data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus, 10 ... Control part, 11 ... CPU, 13 ... ROM, 15 ... RAM, 21 ... Reading unit, 30 ... Carriage conveyance mechanism, 31 ... Carriage, 33 ... Guide shaft, 40 ... ADF, 41 ... Document Tray 42... Discharge tray 43. Separation mechanism 45. Conveyance mechanism 47. Document holding mechanism 49. Paper discharge mechanism 50. Display operation unit 60. Interface 70. , 76 ... Partition plate, 79 ... White reference member, 80 ... Cover, 100 ... External device, 451 ... Paper feed roller, 453, 455 ... Pinch roller, 471 ... Holding plate, MT1, MT2 ... Motor, SN1, SN2 ... Sensor , P ... manuscript, R1 ... home position area, R2 ... ADF reading area, R3 ... FB reading area

Claims (8)

A document conveying means for conveying the document to be read by rotation of a roller from a paper feeding unit holding a document to be read to a paper discharge unit;
A reading unit that optically reads the document conveyed by the rotation of the roller at a position close to the roller in a main scanning direction parallel to an axis of the roller;
Unit conveying means for conveying the reading unit in a sub-scanning direction orthogonal to the main scanning direction;
Control means for controlling the original conveying means, the reading unit and the unit conveying means to cause the reading unit to read the original to be read and to generate read image data representing a read image of the original;
With
The control means includes
The original conveying unit conveys the original to be read from the paper feeding unit, and when the leading end of the original reaches the stop position of the reading unit, the unit is moved to the unit conveying unit. In response to the movement of the original, the reading unit is caused to perform a plurality of reading operations while being conveyed in the sub-scanning direction, so that the original is conveyed to the original conveying means while the original is moved to the reading unit. A first procedure for reading the front end of the head multiple times in the main scanning direction;
Based on each line image data representing a reading result in the main scanning direction generated by the reading unit by the plurality of reading operations realized by the first procedure, according to the first procedure in the conveyance path of the reading unit. The amount of light input to the reading unit is specified at each point in the area where the reading operation is performed, and a single point where the amount of light satisfies a predetermined condition in the sub-scanning direction is set as the optimum position of the reading unit. A second procedure to determine,
After the determination of the optimum position, the reading unit is caused to read the original by causing the reading unit to read the document while carrying the reading unit in a direction to retract the reading unit to the optimum position. A document front area, which is an area in a document up to a document position that can be read when the optimum position is reached, is read by the reading unit, and the reading unit has the read image data as line image data constituting the read image data. A third procedure for generating each line image data representing the reading result of the document front area;
After the reading unit reaches the optimum position, the reading unit is held at the optimum position, and the reading unit is caused to execute a reading operation at the optimum position, and the document is discharged to the document conveying means. The document back area as the area in the document that continues from the document front area to the back in the document transport direction is read by the reading unit, and the read image data is read by the reading unit. A fourth procedure for generating each line image data of the document rear area as line image data to be configured;
To generate read image data representing the read image of the original by combining the line image data generated by the reading unit as line image data constituting the read image data. An image reading apparatus. The document front area is an area excluding the front end portion of the document, and starts from a document position adjacent to the rear side in the transport direction of the front end portion of the document, and is read when the reading unit reaches the optimum position. An area within the document that ends at a possible document position;
The control means uses the line image data representing the reading result of the leading end portion of the document generated by the reading unit in the first procedure as the line image data constituting the read image data. A combination of the data, each line image data of the document front area generated by the third procedure, and each line image data of the document back area generated by the fourth procedure, The image reading apparatus according to claim 1, wherein data is generated.   In the third procedure, when the control unit causes the unit transport unit to transport the reading unit in a direction to move back to the optimum position, the control unit first transports the document to the document transport unit. Once stopped, after the stop, the unit conveying means conveys the reading unit in the direction of retreating to the optimum position, and after the reading unit has reached the optimum position, The image reading apparatus according to claim 1, wherein a conveyance unit is configured to resume conveyance of the document.   The control unit is configured to retract the reading unit to the optimum position among the line image data constituting the read image data based on the light amount information at each point specified in the second procedure. The luminance of each line image data generated by the reading operation performed until the period until is input to the reading unit at the point where the reading operation corresponding to the line image data is performed and at the optimum position. The amount of correction according to the difference from the amount of light is corrected, and read image data representing a read image of the original is generated using each corrected line image data. Item 4. The image reading apparatus according to any one of Items 3 to 4.   5. The image reading apparatus according to claim 1, wherein the control unit determines a point where the amount of light input to the reading unit is maximum as an optimum position of the reading unit.   5. The control unit according to claim 1, wherein the control unit determines a point where the amount of light input to the reading unit coincides with a predetermined reference value as an optimum position of the reading unit. An image reading apparatus according to claim 1. A transparent plate-like table placed on the conveyance path of the reading unit in parallel with the axis of the roller and in parallel with the sub-scanning direction, which is the conveyance direction of the reading unit, and a document to be read A document placement table for placing
The control means generates read image data representing a read image of the original according to the first to fourth procedures when generating the read image data for the original to be read held by the paper feeding unit. When generating the read image data for the original to be read that is generated and placed on the original table, the unit conveying means is provided in a lower area of the original placed on the original table. The reading unit is conveyed in the sub-scanning direction, and the reading unit is caused to perform a reading operation at the time of the conveyance, thereby representing a read image of the original formed by combining line image data generated by the reading operation. It is configured to generate read image data,
The image reading according to claim 6, wherein the reference value is determined by a light amount input to the reading unit when the read image data is generated for the document placed on the document placing table. apparatus. A document conveying means for conveying the document to be read by rotation of a roller from a paper feeding unit holding a document to be read to a paper discharge unit;
A reading unit that optically reads the document conveyed by the rotation of the roller at a position close to the roller in a main scanning direction parallel to an axis of the roller;
Unit conveying means for conveying the reading unit in a sub-scanning direction orthogonal to the main scanning direction;
A program for causing a computer of an image reading apparatus to generate read image data representing a read image of the document,
The original conveying unit conveys the original to be read from the paper feeding unit, and when the leading end of the original reaches the stop position of the reading unit, the unit is moved to the unit conveying unit. In response to the movement of the original, the reading unit is caused to perform a plurality of reading operations while being conveyed in the sub-scanning direction, so that the original is conveyed to the original conveying means while the original is moved to the reading unit. A first procedure for reading the front end of the head multiple times in the main scanning direction;
Based on each line image data representing a reading result in the main scanning direction generated by the reading unit by the plurality of reading operations realized by the first procedure, according to the first procedure in the conveyance path of the reading unit. The amount of light input to the reading unit is specified at each point in the area where the reading operation is performed, and a single point where the amount of light satisfies a predetermined condition in the sub-scanning direction is set as the optimum position of the reading unit. A second procedure to determine,
After the determination of the optimum position, the reading unit is caused to read the original by causing the reading unit to read the document while carrying the reading unit in a direction to retract the reading unit to the optimum position. A document front area, which is an area in a document up to a document position that can be read when the optimum position is reached, is read by the reading unit, and the reading unit has the read image data as line image data constituting the read image data. A third procedure for generating each line image data representing the reading result of the document front area;
After the reading unit reaches the optimum position, the reading unit is held at the optimum position, and the reading unit is caused to execute a reading operation at the optimum position, and the document is discharged to the document conveying means. The document back area as the area in the document that continues from the document front area to the back in the document transport direction is read by the reading unit, and the read image data is read by the reading unit. A fourth procedure for generating each line image data of the document rear area as line image data to be configured;
For causing the computer to execute.