JP5987616B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus including the image reading apparatus.

In the image reading apparatus, a sheet-through method for reading an image of a document passing on the first document glass by an ADF unit (automatic document feeder), and a document placed on the document placement glass (second document glass). There are models that employ both a moving optical system that reads images.
Such an image reading apparatus usually includes a carriage (light source unit) on which a linear light source is mounted. The carriage is movable in the sub-scanning direction in a state where the linear light source is mounted along the main scanning direction.

  When reading an original image by the sheet-through method, the carriage is stationary at a position below the first original glass, and the light from the linear light source is applied to the original passing through the first original glass. When the original image is read by the moving optical system, the carriage is moved below the second original glass along the sub-scanning direction, and during the movement, the light from the linear light source is changed to the second original glass. The document placed on the top is irradiated.

In either case, the light reflected by the document is received by the image sensor, and image data corresponding to the document image is generated based on the output of the image sensor.
When reading an image of a document by the moving optical method, it is necessary to determine a reading start timing so that reading of an image from one end of the document in the sub-scanning direction (reading of the output of the image sensor) is started. Usually, the reading start timing is set based on the time required for the carriage positioned at the home position to move to the reading start position. For this purpose, control of positioning the carriage at the home position is performed, and image reading is started at an appropriate timing.

  In Patent Document 1, a detection pattern optically readable by an image sensor is provided at a position corresponding to the home position, and first, in the sub-scanning direction regardless of whether the carriage is positioned at the home position. A configuration is disclosed in which the carriage is guided to the home position by starting this movement and reading this detection pattern during the movement.

JP 2001-5119 A

  The control for positioning the carriage at the home position is executed prior to reading the document image, such as when the power is turned on. For this reason, when the power is turned on, the original image cannot be read until the carriage is positioned at the home position. In the configuration of Patent Document 1, since the position of the carriage cannot be specified at the start of control for positioning the carriage at the home position, even if the carriage is at the home position, the carriage is first moved and then moved. The position of the carriage must be identified by reading the detection pattern inside.

  As described above, since the carriage movement control is always performed, the reading of the document image is delayed. If the moving speed of the carriage is increased, the delay in reading the original image can be improved. However, since the carriage movement is normally set at a speed suitable for the reading speed of the original image, to increase the carriage movement requires a drastic change in the configuration of the carriage movement system. Is not realistic.

  The present invention solves such a problem, and an object thereof is to provide an image reading apparatus and an image forming apparatus capable of specifying the position of the carriage in a short time when the power is turned on.

  In order to achieve the above object, an image reading apparatus according to the present invention irradiates a stationary original with light from the light source while moving the light source along the sub-scanning direction and reflects the light on the original. A moving optical system that reads an image of the document by receiving the received light with an imaging unit, and light emitted from the light source unit in a state where the light source unit is stationary at a position below the translucent member. An image reader capable of switching and executing a sheet-through method of reading an image of a document by irradiating a document passing over a translucent member and receiving the reflected light by the imaging unit, A rotating body disposed above the translucent member so as to be rotatable about a rotation axis parallel to a main scanning direction and having an outer peripheral surface for guiding a document passing on the translucent member; Rotating body circumference An optically readable mark provided on the light source, an angle detecting means for detecting a rotation angle of the rotating body, and the light source in a stationary state by rotating the rotating body when reading of a document image is not performed. Based on the rotation angle detected by the angle detection means when the reflected light from the mark of the light emitted from the part is detected by the imaging means, the position of the light source part in the stationary state in the sub-scanning direction is determined. And control means for controlling the reading operation of the original document.

  In addition, an image forming apparatus according to the present invention includes the image reading device.

In the image reading apparatus according to the present invention, the position of the light source unit can be specified only by rotating the rotating body. Therefore, the position of the light source unit is determined more than when the light source unit is moved in the sub-scanning direction to specify the position. The time required for specifying the position can be shortened. As a result, the subsequent document image reading operation can be started quickly.
Preferably, when it is specified that the light source unit in a stationary state is located within a predetermined range below the translucent member, the control unit then specifies the light source unit in a sheet-through method. The document image reading operation is executed in a state where the document is placed, and the moving optical system starts the movement of the light source unit from the specified position and executes the reading operation.

  Preferably, when the light source unit is specified to be at a reference position within the predetermined range, the control unit reads the image by the imaging unit at a predetermined timing when a subsequent document image reading operation is performed. And starting timing of reading by the imaging means is corrected based on the deviation.

  Preferably, when the mark is not detected by the imaging unit, the control unit sets the rotating body to a rotational position where the mark should be detected by the imaging unit if the light source unit is at a reference position. In a state where the light source unit is positioned, the light source unit is moved in the sub-scanning direction in a lighting state, and the light source unit is stopped at the reference position based on the position of the light source unit when the mark is detected by the imaging unit. It is characterized by making it.

  Preferably, a correction reference surface for shading correction is provided on the outer peripheral surface of the rotating body, and the control unit determines that the light source unit is located within the predetermined range when the light source unit is located within the predetermined range. The rotator is subjected to shading correction based on the amount of light reflected from the correction reference plane of the light emitted from the light source unit in a state where the correction reference plane is at a rotation position detected by the imaging means. And

Preferably, the control means executes processing for specifying a position of the light source unit when power is turned on.
Preferably, the control means executes processing for specifying the position of the light source unit when an instruction to read an image of a document is given.
Preferably, the rotating body is provided with a cleaning member that slides and cleans the upper surface of the translucent member by the rotation of the rotating body.

Preferably, the imaging means is movable with the light source unit.
Preferably, the imaging means is fixed at a position where the reflected light from the document can be received via a reflecting mirror.

FIG. 2 is a schematic diagram for explaining a configuration of an MFP apparatus according to an embodiment of the present invention. 2 is a schematic diagram for explaining a configuration of a main part of an image reading apparatus provided in the MFP apparatus. FIG. It is a schematic diagram which shows the structure of the cross section of the rotating member provided in the ADF unit on the image reading apparatus. It is a perspective view of the rotation member. It is a block diagram of the principal part of the control system which performs carriage position specific control in the control system of an image reading apparatus. It is a schematic diagram which shows the state which the rotary body of the rotation member became a detection position. 10 is a table showing a relationship between a rotation angle of a rotating body and a luminance level of a signal output from an image sensor when a carriage is positioned at a home position. FIG. 6 is a schematic diagram for explaining a state in which light from a linear light source is irradiated to a rotating body at a detection position when a deviation in the sub-scanning direction of the carriage is within a detection range. FIG. 6 is a schematic diagram for explaining a state in which light emitted from a linear light source of the carriage is applied to the central portion in the circumferential direction of the rotational position detection mark when the carriage is displaced in the first direction. 6 is a table showing a relationship between a rotation angle of a rotating body and a luminance level of a signal output from an image sensor when a carriage is displaced from a home position in a first direction. 6 is a table showing a relationship between a rotation angle of a rotating body and a luminance level of a signal output from an image sensor when a carriage is displaced from a home position in a second direction. 5 is a flowchart illustrating a processing procedure of initialization control executed when a printer is turned on in a reading control unit.

FIG. 1 is a schematic diagram for explaining the configuration of an MFP (Multi Function Peripheral) apparatus according to an embodiment of the present invention. As shown in FIG. 1, the MFP apparatus includes an image reading apparatus A that reads an image of a document and an image forming body B that forms a toner image by an electrophotographic method.
The image reading apparatus A includes an image reading unit (image reading mechanism) 10 provided on the image forming body B, and an ADF unit (automatic document feeder) 40 provided on the image reading unit 10. .

  On the upper surface of the image reading unit 10, the first original glass (translucent member) 13 in the form of an elongated strip whose longitudinal direction is along the main scanning direction (from the front side to the rear side of the MFP apparatus), and the first A plate-like second original glass (translucent light) disposed at a predetermined interval on the right side (hereinafter simply referred to as “right side” and the opposite side as “left side”) from the front side to the back side of the original glass 13. Sex member: original placing glass) 16.

The image reading unit 10 uses both a sheet-through method for reading an image of a document conveyed by the ADF unit 40 and a moving optical method for reading an image of a document placed on the second document glass 16 by a user. The image can be read.
The ADF unit 40 conveys the documents placed on the document feed tray 41 one by one toward the first document glass 13 of the image reading unit 10 and passes the document on the first document glass 13. The image reading unit 10 reads an image of a document passing through the first document glass 13 by the ADF unit 40 and generates image data of the document. Further, when a document is placed on the second document glass 16, the image reading unit 10 reads the image of the document and generates image data of the document.

<Image forming body>
The image forming body B forms a toner image on the recording sheet S based on the image data of the document generated by the image reading unit 10. The image forming main body B can also form a toner image on the recording sheet S based on image data transmitted from an external terminal device.

As shown in FIG. 1, the image forming main body B includes an image forming unit 20 provided in the upper part and a paper feeding unit 30 provided in the lower part.
The image forming unit 20 includes an intermediate transfer belt 25 that is arranged so as to be able to move around in a substantially central portion in the vertical direction of the image forming body B. In the intermediate transfer belt 25, the upper belt running portion moves in the direction indicated by the arrow X, and the lower belt running portion moves in a direction almost opposite to the arrow X in a substantially horizontal state.

Below the lower belt running portion of the intermediate transfer belt 25, process units 20Y, 20M, 20C, and 20K are sequentially arranged along the running direction of the lower belt running portion.
In each of the process units 20Y, 20M, 20C, and 20K, photosensitive drums 21Y, 21M, 21C, and 21K are provided below the lower belt running portion of the intermediate transfer belt 25, respectively. Each of the photosensitive drums 21Y, 21M, 21C, and 21K is configured to rotate along the lower belt running portion while facing the lower belt running portion of the intermediate transfer belt 25.

Each of the process units 20Y, 20M, 20C, and 20K has a toner image of each color of yellow (Y), magenta (M), cyan (C), and black (K) by the photosensitive drums 21Y, 21M, 21C, and 21K. Form.
Each of the process units 20Y, 20M, 20C, and 20K has substantially the same configuration except that only the color of the toner for forming the toner image is different. Only the configuration of the process unit 20K disposed on the most downstream side (rightmost side) in the traveling direction will be described in detail, and detailed description of the configuration of the other process units 20Y, 20M, and 20C will be omitted.

Around the photosensitive drum 21K of the process unit 20K, a charger 22K, an exposure unit 23K, and a developing unit 24K are provided in order along the rotation direction of the photosensitive drum 21K.
The charger 22K uniformly charges the surface (outer peripheral surface) of the rotating photosensitive drum 21K. The exposure device 23K irradiates the charged surface of the photosensitive drum 21K with a light beam by a drive signal based on image data. The light beam emitted from the exposure device 23K is scanned in the axial direction (main scanning direction) on the surface of the rotating photosensitive drum 21K. Thereby, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 21K.

The developing device 24K develops the electrostatic latent image on the photosensitive drum 21K with K-color toner. As a result, a K toner image corresponding to the electrostatic latent image is formed on the photosensitive drum 21K.
A primary transfer roller 26 </ b> K that faces the photosensitive drum 21 </ b> K with the intermediate transfer belt 25 interposed therebetween is disposed inside the circumferential movement area of the intermediate transfer belt 25. The toner image formed on the photosensitive drum 21K is primarily transferred onto the intermediate transfer belt 25 by the action of an electric field formed by the primary transfer roller 26K to which a transfer bias voltage is applied.

  Primary transfer rollers 26Y, 26M, and 26C facing the respective photosensitive drums 21Y, 21M, and 21C with the intermediate transfer belt 25 interposed therebetween are also provided above the other image forming units 20Y, 20M, and 20C. The toner images formed on the photosensitive drums 21Y, 21M, and 21C are transferred onto the intermediate transfer belt 25 by the action of the electric field formed by the primary transfer rollers 26Y, 26M, and 26C to which the transfer bias voltage is applied. Primary transfer is performed.

When forming a full-color image, toner images of each color Y, M, C, and K are superimposed and transferred onto the same region on the intermediate transfer belt 25 that is moving around.
The toner image transferred onto the intermediate transfer belt 25 is conveyed to the downstream end portion (right end portion) in the moving direction of the lower running portion of the intermediate transfer belt 25 by the circumferential movement of the intermediate transfer belt 25. . Note that a secondary transfer roller 27 is pressed against this end portion of the intermediate transfer belt 25.

  A plurality of paper feed cassettes 31 are provided in the paper feed unit 30 provided below the process units 20Y, 20M, 20C, and 20K. When the toner image is formed in the image forming main body B, the paper feeding unit 30 feeds out one recording sheet S from any one of the paper feeding cassettes 31 and presses the intermediate transfer belt 25 and the secondary transfer roller 27. Transport to (secondary transfer position). When the recording sheet S passes through the pressure contact portion between the intermediate transfer belt 25 and the secondary transfer roller 27, the toner image on the intermediate transfer belt 25 is secondarily transferred.

  A fixing device 29 is provided above the secondary transfer position where the intermediate transfer belt 25 and the secondary transfer roller 27 are pressed against each other, and the recording sheet S that has passed the secondary transfer position is conveyed to the fixing device 29. . The recording sheet S to which the toner image has been transferred is heated and pressurized while passing through the fixing device 29, whereby the toner image transferred onto the recording sheet S is thermally fixed. The recording sheet S on which the toner image is fixed is discharged onto the recording sheet tray 28.

<Image Reading Unit of Image Reading Device>
FIG. 2 is a schematic diagram for explaining a configuration of a main part in the image reading apparatus A. As shown in FIG. 2, inside the image reading unit 10 provided at the lower part of the image reading apparatus A, along the upper surface on which the first original glass 13 and the second original glass 16 are provided, the main scanning direction and Is provided with a carriage (light source unit) 18 slidable in an orthogonal direction (sub-scanning direction). The carriage 18 has a linear light source 18a whose longitudinal direction is linearly arranged along the main scanning direction, and an original or second original glass irradiated from the linear light source 18a and passing over the first original glass 13. An image sensor (imaging means) 18b to which light reflected by a document placed on 16 is irradiated is mounted.

The linear light source 18a is usually composed of a lamp using a rare gas such as a fluorescent lamp or a xenon lamp, an external electrode light source, an LED, and the like, and almost the entire length of the first original glass 13 in the main scanning direction. It is the structure which can irradiate light over.
The image sensor 18b is configured by a line sensor in which a CCD (Charge Coupled Device) having a plurality of photoelectric conversion elements arranged along the main scanning direction is mounted linearly on a substrate. The image sensor 18b is mounted on the carriage 18 with the line sensor along the main scanning direction.

  The carriage 18 is positioned and stopped at a preset home position below the first document glass 13 in initialization control executed when the MFP apparatus is powered on. When the initialization control is completed, when reading an image of a document passing on the first document glass 13 after that, the carriage 18 turns on the linear light source 18a in a stationary state at the home position. . In this state, when the document is conveyed to the first document glass 13 by the ADF unit 40, the document passing through the first document glass 13 is irradiated with light from the linear light source 18a.

The image sensor 18b receives the light reflected by the original passing through the first original glass 13, and outputs a signal corresponding to the amount of received light. The signal output from the image sensor 18b is supplied to an image processing unit (not shown), and the image processing unit generates image data corresponding to the image of the document.
When reading an image of a document placed on the second document glass 16, the carriage 18 moves from the home position along the lower surface of the second document glass 16 to the position shown in FIG. Slide in the first direction indicated by arrow G. While the carriage 18 is slid, the linear light source 18a is turned on, and the light from the linear light source 18a is applied to the document placed on the second document glass 16 and reflected by the document. The light reflected by the original on the second original glass 16 is received by the image sensor 18b.

The image reading motor 17 is, for example, a pulse motor, and slides the carriage 18 in the sub-scanning direction at a predetermined speed at which the image on the second original glass 16 can be appropriately read by the image sensor 18b.
When the carriage 18 is slid in the first direction over a predetermined distance corresponding to the size of the document placed on the second document glass 16, the image reading motor 17 is driven in reverse. Accordingly, the carriage 18 is slid in a second direction that is opposite to the first direction indicated by the arrow G. When the carriage 18 returns to the home position, the image reading motor 17 is stopped.

<ADF unit of image reading apparatus>
As shown in FIG. 2, the ADF unit 40 provided on the image reading unit 10 is provided with a transport path 49 for transporting the document D onto the first document glass 13 in the upper area of the first document glass 13. In addition, a document feed tray 41 on which a document transported to the transport path 49 is placed is provided above the second document glass 16.

  The document placed on the document feed tray 41 is sent from the document feed tray 41 to the transport path 49 by the pickup roller 42 and transported along the transport path 49 along the horizontal direction by the pair of feed rollers 43. After that, the registration roller pair 44 conveys the sheet in a circularly curved conveyance path 49 downward. Thereafter, the original is transported above the first original glass 13 by the pre-reading roller pair 45 and passes over the first original glass 13.

  Above the first original glass 13, a rotating body 51 that rotates about a rotation axis along the main scanning direction, and a paper that rotates integrally with the rotating body 51 and adheres to the surface of the first original glass 13. A rotating member 50 having a cleaning brush (cleaning means) 52 for removing foreign substances such as powder is provided. As will be described later, the rotating body 51 is configured to be rotated by a rotating body motor 53 (see FIG. 3).

  When reading an image of a conveyed document, the rotating body 51 is opposed to the first document glass 13 with the cleaning brush 52 facing upward. In such a state, the document passes between the rotating body 51 and the first document glass 13. In this case, the carriage 18 is stationary at the home position below the first document glass 13, and light from the linear light source 18 a of the carriage 18 passes between the rotating body 51 and the first document glass 13. The image sensor 18b receives the reflected light from the first surface which is irradiated onto the surface (first surface) directed downward of the original.

When the upper surface of the first original glass 13 is cleaned by the cleaning brush 52, the rotating body 51 is rotated once. Accordingly, the cleaning brush 52 slides on the upper surface of the first original glass 13 to remove foreign matters such as paper dust attached to the upper surface of the first original glass 13. A specific configuration of the rotating member 50 will be described later.
The document D that has passed over the first document glass 13 passes through the lower area of the back surface reading unit 61. The back side reading unit 61 includes a pair of linear light sources that irradiate light on a surface (second surface) directed upward of the document that passes below, and each linear light source reflected on the second surface of the document. And a contact image sensor (CIS) that receives light. The contact image sensor is configured by an image sensor in which CCDs are arranged linearly along the main scanning direction.

The back surface reading unit 61 irradiates light from a pair of linear light sources onto the second surface of the document passing below and receives the reflected light by the contact image sensor. The contact image sensor outputs a signal corresponding to the image data on the second surface of the document.
The original that has passed under the back side reading unit 61 is conveyed by the post-reading roller pair 47 and the original discharge roller pair 48 and discharged onto the original discharge tray 46.

  A rotating member 62 for cleaning the light irradiation surface of the back surface reading unit 61 is provided below the back surface reading unit 61. Similar to the rotation member 50, the rotation member 62 rotates around the rotation axis along the main scanning direction, and rotates together with the rotation body to adhere to the light irradiation surface of the back surface reading unit 61. A cleaning brush for removing foreign matters such as paper dust is provided, and the light irradiation surface of the back surface reading unit 61 is cleaned by the cleaning brush when the rotating body rotates.

<Rotating member>
FIG. 3 is a schematic diagram showing a configuration of a cross section of the rotating member 50 provided in the ADF unit 40 on the image reading unit 10 together with the carriage 18, and FIG. 4 is a perspective view of the rotating member 50.
The rotating body 51 of the rotating member 50 is a shaft body having an axis (rotating axis) Ox along the main scanning direction (corresponding to a direction perpendicular to the paper surface). The rotating body motor 53 (see FIG. 4) rotates the rotating shaft Ox. Is rotated in the direction indicated by the arrow E.

  The rotating body 51 is configured, for example, in a shape in which a part of a metal cylinder having a constant outer diameter is cut out along the main scanning direction so that a flat surface 51a parallel to the rotation axis Ox is formed. The cross section has a “D” shape. Accordingly, the outer surface of the rotating body 51 in the rotation direction is formed by a flat surface 51a formed in an elongated rectangular shape along the main scanning direction and a circumferential surface having a constant radius R (for example, 7 mm) along the rotation direction. Outer peripheral surface 51b. The outer peripheral surface 51b of the rotating body 51 is formed over a central angle range of about 220 °, and is white so that light can be reflected.

  As shown in FIG. 3, the axis Ox of the rotator 51 is disposed substantially at the center of the first document glass 13 in the sub-scanning direction (width direction), and passes through the first document glass 13. When the image of the first surface is read, as shown in FIG. 3, the flat surface 51a is in a horizontal state and is directed upward. In this case, the outer peripheral surface 51 b of the rotating body 51 is in a state of facing the first original glass 13, and a gap of about 1 to 2 mm is formed between the first original glass 13. The document passes between the outer peripheral surface 51 b of the rotating body 51 and the first document glass 13.

  In the following, a plane perpendicular to the flat surface 51a and including the axis Ox is defined as a reference plane Lo of the rotating body 51, and the flat surface 51a is on the side opposite to the first original glass 13 with the axis Ox interposed therebetween ( The state of the rotating body 51 (the state shown in FIG. 3) when the reference plane Lo is vertical in the state of being positioned on the upper side) is set as the standard position of the rotating body 51. Further, the rotation angle when the rotating body 51 rotates in the direction of arrow E from the standard position is defined as “α”.

When reading the image of the first surface of the document passing over the first document glass 13, the rotating body 51 is set to the standard position (α = 0 °), and the carriage 18 is connected to the secondary document below the first document glass 13. It is positioned (still) within an initial area FA within a predetermined range along the scanning direction. The specific length of the initial area FA in the sub-scanning direction will be described later.
The initial area FA has both sides in the sub-scanning direction centered on a position (reference position) where each optical axis of the line sensor in the image sensor 18b overlaps the reference surface Lo of the rotating body 51 at the standard position. Is set to a certain length. In the following, this reference position is referred to as the home position HP of the carriage 18.

  On the outer peripheral surface 51b of the rotating body 51, a white band having a band shape (circumferential length) having a constant width along the axial direction in a portion adjacent to the flat surface 51a on the upstream side in the rotation direction of the rotating body 51. A correction reference plane 55 is provided. The correction reference surface 55 is used when performing shading correction of the linear light source 18a, and is formed by the surface of a white PET film attached to the outer peripheral surface 51b of the rotating body 51, for example. .

  The correction reference surface 55 is formed in a range (circumferential length) of a constant central angle θc, and is provided over the entire area of the rotating body 51 in the axial direction. The correction reference surface 55 is brought into a state facing the first original glass 13 by the rotation of the rotating body 51 when the shading correction is performed. In this case, the carriage 18 is stopped in the initial area FA, and shading correction is executed.

The outer peripheral surface 51b of the rotator 51 is a black strip that is in the form of a strip having a constant width (circumferential length) along the axial direction on the downstream side in the rotational direction of the rotator 51 and in the vicinity of the flat surface 51a. The rotational position detection mark 56 is provided. The rotation position detection mark 56 is formed by the surface of the black PET film affixed on the outer peripheral surface 51b of the rotary body 51, for example.
The rotational position detection mark 56 is used to specify the position of the carriage 18 in the sub-scanning direction when performing control for positioning the carriage 18 in the initial area FA at a predetermined timing when reading of the document image is not performed. Is done.

  The rotational position detection mark 56 has a predetermined position at a position on the outer peripheral surface 51b that is away from the reference surface Lo of the rotating body 51 in a direction opposite to the rotational direction indicated by the arrow E by a predetermined center angle θa. The circumferential length in the range of the central angle θb (about 10 to 20 °) is provided over the entire area of the rotating body 51 in the axial direction as shown in FIG. Therefore, when the rotator 51 is rotated by [θa + (θb / 2)] in the direction indicated by the arrow E from the standard position, as shown in FIG. 6, the circumferential direction (width direction) of the rotation position detection mark 56 is obtained. The central portion faces the first original glass 13 in the state of being closest.

In the following description, the position of the rotating body 51 in which the central portion in the circumferential direction of the rotation position detection mark 56 faces the first original glass 13 in the closest state (as shown in FIG. The position where the angle α is [θa + (θb / 2)]) is set as the detection position of the rotating body 51.
The white outer peripheral surface 51b of the rotating body 51 is exposed except for portions where the correction reference surface 55 and the rotation position detection mark 56 are provided. Therefore, the white outer peripheral surface 51b of the exposed rotating body 51 can reflect the light emitted from the linear light source 18a.

When the light emitted from the linear light source 18a is applied to the black rotation position detection mark 56, the rotation position detection mark 56 does not reflect the light, so that the light is emitted from the linear light source 18a to the outer peripheral surface 51b of the rotating body 51. The amount of light received by the image sensor 18b is lower than when the emitted light is irradiated.
In the following, when the amount of light received by the image sensor 18b is equal to or smaller than a predetermined threshold value set in advance, the luminance level of the signal output from the image sensor 18b is a black level, which is larger than the threshold value. In addition, the luminance level of the signal output from the image sensor 18b is set to the white level.

  Specifically, the above threshold value is such that the luminance level of the signal output from the image sensor 18b when the light is irradiated from the linear light source 18a to the rotational position detection mark 56 is a black level, and the linear light source When the light 18a is reflected by the exposed outer peripheral surface 51b of the rotating body 51, the luminance level of the signal output from the image sensor 18b is set to the white level.

Therefore, when the carriage 18 is located at the home position HP, if the rotating body 51 is in the detection position, the light emitted from the linear light source 18a is applied to the rotation position detection mark 56. The luminance level of the signal output from the image sensor 18b is a black level.
The rotational position detection mark 56 is disposed at an appropriate interval from the downstream side edge in the rotational direction of the outer peripheral surface 51 b of the rotating body 51. Therefore, when the carriage 18 is positioned at the home position HP, the luminance level of the signal output from the image sensor 18b is from the white level when the rotation angle α of the rotating body 51 is in the range of 0 to 100 °. It changes to the black level and then changes to the white level.

The range (circumferential length) of the central angle θb of the rotational position detection mark 56 ensures that the luminance level of the output signal of the image sensor 18b is black level even when the rotating body 51 is rotated at high speed. The diameter is set based on the diameter of the rotating body 51, the rotation speed, and the like.
The white outer peripheral surface 51b adjacent to the correction reference surface 55 on the upstream side in the rotational direction of the rotator 51 has a first central angle γ range (circumferential length) of about 80 °, for example. When the document passes over the document glass 13, the guide surface 51 f guides the document while facing the first document glass 13.

The position where the rotational position detection mark 56 is provided on the outer peripheral surface 51b of the rotating body 51 is not particularly limited, and is appropriately set according to the circumferential length of the correction reference surface 55 and the guide surface 51f. The
A cleaning brush 52 is provided on the flat surface 51 a of the rotating body 51. The cleaning brush 52 is formed by flocking brush hairs along the axial direction of the rotator 51 at a central portion in the width direction of the flat surface 51 a of the rotator 51 along the axial direction of the rotator 51.

  As shown in FIG. 4, rotary shafts 51m and 51n projecting outward from the respective end surfaces along the axial center are provided on the respective end surfaces on both sides in the axial direction of the rotating body 51, and one rotary shaft 51m is provided. In addition, the rotational force from the rotating body motor 53 described above is transmitted. The rotator motor 53 rotates the rotator 51 at a higher speed than the moving speed of the carriage 18 in the sub-scanning direction by the image reading motor 17.

  The other rotation shaft 51n is provided with a rotation angle detector 54 for detecting the rotation angle of the rotating body 51. The rotation angle detector 54 includes a rotating disk 54a that rotates integrally with the rotating shaft 51n, and a photosensor 54d having a light emitting element 54b and a light receiving element 54c. The rotating disk 54a is coaxially attached to the rotating shaft 51n, and a plurality of slits 54e are provided in the outer peripheral edge region of the rotating disk 54a, for example, at a constant interval in the circumferential direction over a range of 100 °. Is formed.

  The light emitting element 54b and the light receiving element 54c of the photosensor 54d are opposed to each other across the region where the slit 54e is formed in the rotating disk 54a, and the photosensor 54d is located between the light emitting element 54b and the light receiving element 54c. , The light emitted from the light emitting element 54b is received by the light receiving element 54c through the slit 54e.

The slit 54e in the rotating disk 54a is provided so as to pass between the light emitting element 54b and the light receiving element 54c while the rotating body 51 rotates from the standard position in the direction indicated by the arrow E over 100 °.
Therefore, when the rotating body 51 rotates in the direction of arrow E to the standard position, the rotation angle detector 54 has a region of the rotating disk 54a that passes between the light emitting element 54b and the light receiving element 54c as a slit. It changes from the area | region in which 54e is not formed to the area | region in which the slit 54e was formed. As a result, the light receiving element 54c changes from a state where the light from the light emitting element 54b is not received to a state where the light is received. Therefore, when the rotator 51 rotates in the direction of arrow E, the rotator 51 can detect the time when the output of the rotation angle detector 54 first enters the light receiving state as the standard position.

  Further, when the rotating body 51 rotates in the direction indicated by the arrow E over 100 ° from the standard position, the slit continuously passes between the light emitting element 54b and the light receiving element 54c during the rotation. 54c intermittently receives light from the light emitting element 54b. Therefore, by counting the number of times of light reception (number of pulses) by the light receiving element 54c, the rotation angle α of the rotating body 51 in the direction indicated by the arrow E from the standard position can be detected over 100 °.

Note that the rotation angle α of the rotating body 51 is not limited to the configuration detected by the rotation angle detector 54 having such a configuration. For example, as a configuration in which the rotating body 51 is rotated at a constant speed, the rotation angle α of the rotating body 51 may be calculated based on the rotation time of the rotating body 51 from the standard position.
Alternatively, a configuration using a pulse motor as the rotating body motor 53 may be adopted. In this case, the rotation angle α of the rotating body 51 can be calculated based on the number of pulses of the pulse signal when the rotating body 51 rotates. Furthermore, it is good also as a structure which provides the rotary encoder in any one of the rotating shafts 51m and 51n, and calculates the rotation angle (alpha) of the rotary body 51 by counting the pulse number output from a rotary encoder.

  As shown in FIG. 3, when the rotator 51 is at the standard position and the carriage 18 is at the home position HP, the rotator 51 moves in the direction of arrow E with the linear light source 18a turned on. When rotating, the light emitted from the linear light source 18a is irradiated from the state of being irradiated on the exposed outer peripheral surface 51b of the rotating body 51 to the rotating position detection mark 56 as the rotating body 51 rotates. After that, the light from the linear light source 18a is applied to the flat surface 51a.

  Therefore, when the carriage 18 is positioned at the home position HP, if the rotating body 51 rotates in the direction of arrow E over 100 ° from the standard position while the linear light source 18a is lit, the rotation position detection mark 56 is displayed. Except for the period when the light from the linear light source 18a is irradiated, the luminance level of the output signal of the image sensor 18b becomes a white level, and the rotational position detection mark 56 is irradiated with the light from the linear light source 18a. During the period, the luminance level of the output signal of the image sensor 18b becomes a black level.

  Further, even when the carriage 18 is displaced in the sub-scanning direction with respect to the home position HP, the carriage 18 is positioned within the range in which the light from the linear light source 18a is irradiated on the outer peripheral surface 51b of the rotating body 51. While the rotating body 51 is rotated in the direction of arrow E over 100 ° from the standard position, the rotational position detection mark 56 is irradiated with the light from the linear light source 18a. Accordingly, also in this case, the luminance level of the signal output from the image sensor 18b changes from the white level to the black level.

In the following, the range in the sub-scanning direction of the carriage 18 in which the light of the linear light source 18a in the lit state is irradiated onto the rotation position detection mark 56 is referred to as a detection range RA of the carriage 18.
The rotation angle α of the rotator 51 at the time when the luminance level of the signal output from the image sensor 18b changes from the white level to the black level is determined when the carriage 18 is positioned at the home position HP and at the home position HP. It is different from the case where it is not. When the carriage 18 is not located at the home position HP, the rotation angle α at the time when the luminance level of the signal output from the image sensor 18b changes from the white level to the black level is the sub-angle of the carriage 18 with respect to the home position HP. It changes according to the amount of deviation in the scanning direction.

  From the above, in this embodiment, when the rotating body 51 is rotated in the direction of arrow E from the standard position with the carriage 18 stationary and the linear light source 18a turned on, the image sensor 18b outputs the signal. Control for detecting the rotation angle α of the rotating body 51 at the time when the luminance level of the signal changes from the white level to the black level, and specifying the position of the carriage 18 in the sub-scanning direction based on the rotation angle α (carriage position specifying control) ).

<Control system of image reading apparatus>
FIG. 5 is a block diagram of a main part that executes carriage position specifying control in the control system of the image reading apparatus A.
The carriage position specifying control is executed by the reading control unit 65. The reading control unit 65 is given the output of the image sensor 18 b provided in the image reading unit 10 and the output of the rotation angle detection sensor 54 provided in the ADF unit 40. The rotation angle detection sensor 54 outputs a signal corresponding to the rotation angle α of the rotating body 51 as described above.

  The reading control unit 65 moves the carriage 18 of the image reading unit 10 in the sub-scanning direction in both cases of reading a document image by the sheet-through method and the moving optical method and executing the carriage position specifying control. The reading motor 17, the rotating body motor 53 that rotates the rotating body 51 of the rotating member 50, and the linear light source 18 a mounted on the carriage 18 are controlled.

<Carriage position identification control>
Next, details of the carriage position specifying control executed in the reading control unit 65 will be described.
When the rotator 51 is rotated over the rotation angle [θa + (θb / 2)] in the direction indicated by the arrow E from the standard position (rotation angle α = 0 °) shown in FIG. The detection position shown in FIG. When the rotating body 51 is in such a detection position, when the carriage 18 is positioned at the home position HP, the light emitted from the linear light source 18a is reflected in the circumferential direction ( It is irradiated to the center part in the width direction. As a result, the luminance level of the signal output from the image sensor 18b becomes a black level.

  Since the rotational position detection mark 56 is formed in the circumferential direction of the rotating body 51 in the range of the central angle θb, when the carriage 18 is located at the home position HP, When the rotation angle α in the direction indicated by the arrow E from the standard position becomes [θa], the light emitted from the linear light source 18a is applied to the rotation position detection mark 56, and the signal output from the image sensor 18b. The luminance level changes from the white level to the black level.

FIG. 7 is a table showing the relationship between the rotation angle α of the rotating body 51 and the luminance level of the signal output from the image sensor 18b when the carriage 18 is located at the home position HP.
As shown in FIG. 7, when the rotation angle α of the rotating body 51 from the standard position is smaller than [θa] (α = 0 to [θa]), the luminance level of the signal output from the image sensor 18b is the white level. ((A) of FIG. 7).

When the rotation angle α of the rotator 51 is in the range of [θa] to [θa + θb], the light emitted from the linear light source 18a is applied to the rotation position detection mark 56, and thus the signal output from the image sensor 18b. The luminance level becomes black level ((b) in FIG. 7).
Further, when the rotation angle α of the rotating body 51 is in the range of [θa + θb] to 100 °, the light emitted from the linear light source 18a is not irradiated to the rotating position detection mark 56 and is reflected by the outer peripheral surface 51b of the rotating body 51 and the like. Therefore, the luminance level of the signal output from the image sensor 18b becomes a white level ((c) in FIG. 7).

As described above, when the carriage 18 is located at the home position HP, when the rotating light source 51a is turned on in the arrow E direction with the linear light source 18a turned on, the rotation angle α of the rotating body 51 is set. When [θa] is reached, the luminance level of the signal output from the image sensor 18b changes from the white level to the black level.
Even if the carriage 18 is not located at the home position HP (a state shifted in the sub-scanning direction), if the carriage 18 is located within the detection range RA, the rotating body 51 moves from the standard position to the direction of arrow E. The light of the linear light source 18a that is in the lit state is irradiated onto the rotation position detection mark 56 while rotating over 100 °. Accordingly, when the light from the linear light source 18a is irradiated onto the rotation position detection mark 56, the luminance level of the output signal of the image sensor 18b changes from the white level to the black level.

  FIG. 8 shows a state in which the light from the linear light source 18a is irradiated to the rotating body 51 at the detection position when the carriage 18 is not located at the home position HP but is located within the detection range RA. It is a schematic diagram for demonstrating. In this case, the position of the carriage 18 indicated by the solid line in FIG. 8 is shifted from the home position HP indicated by the two-dot chain line in FIG. 8 by the distance d1 in the first direction indicated by the arrow G.

  In such a state, even if the rotating body 51 is rotated from the standard position in the direction of arrow E and the rotating body 51 reaches the detection position (the rotation angle α is [θa]), the light emitted from the linear light source 18a. Is not irradiated on the rotation position detection mark 56 but is irradiated on the outer peripheral surface 51 b of the rotating body 51 positioned downstream in the rotation direction with respect to the rotation position detection mark 56. For this reason, the light reflected by the outer peripheral surface 51b of the rotating body 51 is received by the image sensor 18b. Therefore, the luminance level of the signal output from the image sensor 18b becomes a white level.

From this state, when the rotating body 51 further rotates in the direction of arrow E, the light emitted from the linear light source 18a is applied to the rotation position detection mark 56, and the luminance level of the signal output from the image sensor 18b is black. Become a level.
FIG. 9 shows that when the carriage 18 is separated from the home position HP by a distance d1 in the first direction, the light emitted from the linear light source 18a of the carriage 18 is in the circumferential direction (width direction) in the rotational position detection mark 56. It is a schematic diagram for demonstrating the state irradiated to the center part. In FIG. 9, the rotating body 51 further rotates by [(θb / 2) + β] in the direction of arrow E from the detection position (rotating angle α = θa). The state of θa + (θb / 2) + β] is shown.

In this case, the rotation angle β satisfies the following expression (1) (where R is the radius of the rotating body 51).
β = sin ⁻¹ (d1 / R) (1)
In this case, the luminance level of the signal output from the image sensor 18b changes to the black level when the rotation angle α of the rotating body 51 reaches [θa + β].

FIG. 10 shows the rotation angle α of the rotating body 51 and the luminance level of the signal output from the image sensor 18b when the carriage 18 is shifted from the home position HP by the distance d1 in the first direction indicated by the arrow G. It is a table | surface which shows a relationship. Note that β in the table of FIG. 10 satisfies the above equation (1).
As shown in the table of FIG. 10, when the rotation angle α is in the range of 0 to [θa + β], the luminance level of the signal output from the image sensor 18b is a white level ((a) of FIG. 10). When α is in the range of [θa + β] to [θa + β + θb], the luminance level of the signal output from the image sensor 18b is a black level ((b) in FIG. 10). Further, when the rotation angle α is [θa + β + θb] to 100 °, the luminance level of the signal output from the image sensor 18b becomes a white level ((c) in FIG. 10).

On the other hand, when the carriage 18 is shifted from the home position HP by a distance d1 in the second direction opposite to the first direction indicated by the arrow G, a signal output from the image sensor 18b. The range of the rotation angle α of the rotator 51 in which the brightness level of the white light level changes from the white level to the black level is greater than the rotation angle β (= sin ⁻¹ (d1 / R)) becomes smaller.

The relationship between the rotation angle α of the rotating body 51 and the luminance level of the signal output from the image sensor 18b in this case is shown in the table of FIG. However, β shown in the table of FIG. 11 satisfies the above equation (1).
As shown in the table of FIG. 11, the luminance level of the signal output from the image sensor 18b is a white level when the rotation angle α of the rotating body 51 from the standard position is in the range of 0 to [θa−β]. ((A) of FIG. 11), the black level is in the range of [θa−β] to [θa−β + θb] ((b) of FIG. 11), and the white level is in the range of [θa−β + θb] to 100 °. ((C) of FIG. 11).

  Therefore, in the detection range RA, when the carriage 18 is most shifted from the home position HP in the first direction, the rotating body 51 of the rotating body 51 at the time when the luminance level of the signal output from the image sensor 18b becomes the black level. When the rotation angle is [θa + θd], if the rotation angle α (= [θa + β]) is larger than [θa + θd], the carriage 18 is within the detection range RA in a state of being shifted in the first direction with respect to the home position HP. It can be determined that it is located.

  Further, in the detection range RA, when the carriage 18 is most shifted in the second direction from the home position HP, the rotating body 51 at the time when the luminance level of the signal output from the image sensor 18b becomes the black level. Is [θa−θd], if the rotation angle α (= [θa−β]) is smaller than [θa−θd], the carriage 18 is displaced in the second direction with respect to the home position HP. It can be determined that the current position is within the detection range RA.

  In any case, when the rotation angle α of the rotating body 51 at the time when the luminance level of the signal output from the image sensor 18b becomes the black level is not equal to [θa] (the carriage 18 is not positioned at the home position HP). In the case), the difference [β] between the rotation angle α and [θa + θb / 2] is calculated, and the calculated β is substituted into the above equation (1), whereby the first direction with respect to the home position HP or A distance d1 that is the amount of carriage displacement in the second direction can be calculated.

  From the above, when the rotation angle α of the rotator 51 is not less than [θa−θd] and less than [θa] when the luminance level of the signal output from the image sensor 18b becomes the black level ([[ (θa−θd] ≦ α <[θa]), it can be determined that the carriage 18 is located in the detection range RA in a state of being displaced in the second direction, and when α = [θa] The carriage 18 can be determined to be located at the home position HP, and if it is greater than [θa] and less than or equal to [θa + θd] ([θa] <α ≦ [θa + θd]), the carriage 18 It can be determined that it is located within the detection range RA in a state shifted in two directions.

Further, if the luminance level of the signal output from the image sensor 18b does not change from the white level to the black level even when the rotating body 51 is rotated by 100 ° from the standard position in the direction indicated by the arrow E, the carriage 18 is , It can be determined that it is not located within the detection range RA.
When the carriage 18 is not located within the detection range RA, the light emitted from the linear light source 18a is not reflected by the rotating body 51, and the luminance level of the image sensor 18b does not change. In this case, with the rotator 51 as the standard position, the carriage 18 is moved in the sub-scanning direction with the linear light source 18a turned on, and the light emitted from the linear light source 18a is applied to the rotational position detection mark 56. The position of the carriage 18 in the sub-scanning direction is specified based on the change in the luminance level of the image sensor 18b (change from the white level to the black level).

  FIG. 12 is a flowchart illustrating a processing procedure of initialization control that is executed when the printer is turned on in the reading control unit 65. In this initialization control, first, the position of the carriage 18 in the sub-scanning direction is specified by carriage position specifying control. For this purpose, the reading control unit 65 rotates the rotating body 51 by driving the rotating body motor 53, and moves the rotating body 51 to the standard position (rotation angle α = 0 °) based on the output of the rotation angle detector 54. (Step S11 in FIG. 12).

Next, the linear light source 18a mounted on the carriage 18 is turned on (on), and the rotating body motor 53 is driven to rotate the rotating body 51 (step S12). When the rotation of the rotating body 51 is started, the reading control unit 65 reads a signal output from the image sensor 18b (step S13).
The rotating body 51 is rotated until the rotation angle α reaches 100 ° (“NO” in step S15 and “YES” in step S14), or the luminance level of the signal output from the image sensor 18b is white. The process continues until the level changes to the black level ("NO" in step S14 and "YES" in step S15).

  In this case, if the carriage 18 is positioned within the detection range RA, the linear movement is performed until the rotating body 51 rotates 100 degrees from the standard position (α = 0 °) (“NO” in step S14). The light from the light source 18 a is applied to the outer peripheral surface 51 b (guide surface 51 f) that is exposed in the rotating body 51 and then applied to the rotational position detection mark 56. As a result, the luminance level of the signal output from the image sensor 18b changes from the white level to the black level ("YES" in step S15).

In this case, the reading control unit 65 turns off the linear light source 18a mounted on the carriage 18 and turns off the rotating body motor 53 to stop the rotating body 51 (step S16). ).
Next, the position of the carriage 18 is specified based on the rotation angle α of the rotating body 51 when the luminance level of the signal output from the image sensor 18b changes from the white level to the black level (step S17).

  In this case, when the rotation angle α of the rotating body 51 detected by the rotation angle detector 54 is equal to [θa], it is determined that the carriage 18 is located at the home position HP (in step S18). "YES"), the process proceeds to step S31, and shading correction control is performed. The shading correction control after step S31 will be described later.

When the rotation angle α of the rotating body 51 is not [θa], it is determined that the carriage 18 is not located at the home position HP (“NO” in step S18), and based on the rotation angle α of the rotating body 51, It is determined whether the carriage 18 is located in the initial area FA (step S19).
The initial area FA is a guide surface of the rotating body 51 when reading an image of a document passing over the first document glass 13 by the sheet-through method even when the carriage 18 is not positioned at the home position HP. The light reflected by the original guided at 51f is set in a range where the image sensor 18b receives the light in a focused state.

Since the initial area FA is set in this way, when the carriage 18 is positioned in the initial area FA, the first document glass 13 can be moved on without being positioned at the home position HP. The image of the passing document can be read appropriately.
When the image of the document placed on the second document glass 16 is read by the moving optical system, the light reflected by the document is always received in the focused state by the image sensor 18b, so that the sheet through There is no problem as in the case of the method.

From this, if it is determined that the carriage 18 is located in the initial area FA (“YES” in step S19), the process proceeds to step S20 without moving the carriage 18 to the home position HP.
In step S20, since the carriage 18 is not positioned at the home position HP, when the image of the document passing over the first document glass 13 is read after that and placed on the second document glass 16. In each case of reading an image of a document, a correction time for correcting the reading start timing is calculated based on a deviation amount (distance d1) from the home position HP of the carriage 18.

  This is due to the following reason. That is, when it is determined that the carriage 18 is located in the initial area FA, the carriage 18 is not moved to the home position HP, and thus is deviated from the home position HP. Therefore, in both the sheet-through method and the moving optical method, when reading an image of a document, the position where the light from the linear light source 18a is irradiated on the document is a line where the carriage 18 is located at the home position HP. It shifts in the sub-scanning direction with respect to the position irradiated with the light of the light source 18a.

For this reason, when reading of the output of the image sensor 18b (reading of the original image) is started at the same timing as when the carriage 18 is positioned at the home position HP, it is formed on the recording sheet by the generated image data. There is a risk that the image will be misaligned.
From this, when it is determined that the carriage 18 is located in the initial area FA, the reading start timing of the original image is shifted from the home position HP of the carriage 18 when reading the original image thereafter. Correction is made on the basis of the distance d1, which is a quantity.

  As described above, the distance d1 that is the deviation amount of the carriage 18 from the home position HP is the rotation angle α of the rotating body 51 when the luminance level of the signal output from the image sensor 18b changes from the white level to the black level. And based on the equation (1). The correction time of the document image read start timing is obtained based on the calculated deviation amount.

It should be noted that the correction of the reading start timing of the document image differs depending on whether the displacement of the carriage 18 with respect to the home position HP is in the first direction or the second direction.
That is, when the carriage 18 is displaced in the first direction (downstream direction in the document conveyance direction), the position of the light irradiated on the document from the linear light source 18a of the carriage 18 is the carriage 18 positioned at the home position HP. The first light source 18a deviates in the first direction from the position of light irradiated on the original. For this reason, reading of a document image is started when the carriage 18 is positioned at the home position HP, regardless of whether the document passes on the first document glass 13 or the document placed on the second document glass 16. The reading start timing of the document image is delayed by the calculated correction time with respect to the timing.

  On the other hand, when the carriage 18 is displaced in the second direction (upstream side in the document conveyance direction), the position of the light irradiated on the document from the linear light source 18a of the carriage 18 is the carriage positioned at the home position HP. 18 is shifted in the second direction from the position of the light irradiated on the document from 18. For this reason, reading of a document image is started when the carriage 18 is positioned at the home position HP, regardless of whether the document passes on the first document glass 13 or the document placed on the second document glass 16. The reading start timing of the original image is advanced by the calculated correction time with respect to the timing.

  In step S <b> 20, when the correction time of the document reading timing is obtained, the correction time is stored in a storage unit provided in the reading control unit 65. Then, when reading an image of a document conveyed on the first document glass 13, or when reading an image of a document placed on the second document glass 16, the correction of the reading timing stored in the storage unit is performed. Based on the time, the reading start timing of the original image by the image sensor 18b is corrected.

In step S20, when the correction time of the reading start timing of the original image is obtained and stored in the storage unit, the carriage 18 does not move to the home position HP, but proceeds to step S31, where the shading correction of the linear light source 18a is performed. Execute control.
As described above, when the carriage 18 is positioned in the home position HP or the initial area FA, the position of the carriage 18 is determined only by the rotation of the rotating body 51 without moving the carriage 18 in the sub-scanning direction. Can be specified to be located within the home position HP or the initial area FA. In this case, since the rotational speed of the rotating body 51 is higher than the moving speed of the carriage 18, the time required for specifying the position of the carriage 18 is shorter than when specifying the position of the carriage 18 by moving the carriage 18. can do.

If it is determined in step S19 that the carriage 18 is not located in the initial area FA (“NO” in step S19), control for positioning the carriage 18 at the home position HP is executed (step S21).
When the carriage 18 is not located in the initial area FA, the amount of deviation of the carriage 18 from the home position HP is large, so that reading of the document image is started when the document image is read by the sheet-through method. Even if the timing is corrected, the amount of deviation of the carriage 18 with respect to the home position HP is large, and the light reflected by the document may not be brought into focus at the image sensor 18b. Therefore, the carriage 18 is positioned at the home position HP by the control after step S21.

  In step S21, the carriage 18 is moved in a direction opposite to the shifted direction by a distance d1 corresponding to the shift amount in the sub-scanning direction with respect to the home position HP of the carriage 18. As a result, the carriage 18 is positioned at the home position HP. The distance d1 in this case is longer than the length of the initial area FA in the sub-scanning direction, but is shorter than the length of the detection range RA in the sub-scanning direction. Accordingly, the carriage 18 can be positioned at the home position HP by the movement of the relatively short distance d1.

As a result, the carriage 18 is moved to the home position HP in a shorter time compared to the case where a mark is provided at the home position HP and the carriage 18 is positioned at the home position HP by detecting the mark as in the prior art. be able to.
When the carriage 18 is positioned at the home position HP, the process proceeds to step S31 and shading correction control is executed. Accordingly, also in this case, the shading correction control can be started quickly.

When the carriage 18 is positioned at the home position HP in step S21, the image of the document conveyed on the first document glass 13 or the second document glass 16 after the shading correction is executed. When the image of the document placed on the document is read, it is not necessary to correct the reading start timing.
In step S14, the luminance level of the signal output from the image sensor 18b does not change to the black level (“NO” in step S15), and the rotation angle α of the rotating body 51 reaches 100 ° (step S14). Since "YES" in S14), the carriage 18 is not located within the detection range RA, so the process proceeds to step S22, and control for setting the carriage 18 to the home position HP is executed.

  In addition, in order to confirm that the luminance level of the signal output from the image sensor 18b has changed from the white level to the black level, the rotating body 51 is rotated from the standard position (α = 0 °) over 100 °. However, it is not limited to such a configuration. The rotating body 51 may be rotated in the direction of the arrow E over at least a range in which the rotating position can pass the position where the rotation position detection mark 56 is provided from the standard position.

In step S22, the rotating body 51 is rotated so that the rotation angle α from the standard position becomes [θa + (θb / 2)]. As a result, the rotating body 51 becomes a detection position where the rotation position detection mark 56 faces the first document glass 13. When the rotating body 51 reaches the detection position, the rotation of the rotating body 51 is stopped (step S23).
Next, the linear light source 18a provided on the carriage 18 is turned on, and the carriage 18 is moved in the first direction (step S24). When the carriage 18 starts moving, a signal output from the image sensor 18b is read (step S25).

  In this case, when the carriage 18 is positioned in the second direction (upstream direction of the document conveying direction) with respect to the rotating body 51, a part of the light emitted from the linear light source 18a is image read. It is irregularly reflected by the upper surface of the apparatus A and received by the image sensor 18b. For this reason, the luminance level of the signal output from the image sensor 18b becomes a white level. In such a state, when the carriage 18 is moved in the first direction and is positioned in the vicinity of the home position HP below the rotating body 51, the light emitted from the linear light source 18a is rotated to the rotational position detection mark 56. Is irradiated to the side edge located on the downstream side in the rotational direction indicated by arrow E in FIG. Thereby, the luminance level of the signal output from the image sensor 18b changes to the black level.

As described above, when the luminance level of the signal output from the image sensor 18b changes to the black level (“YES” in step S26), the carriage 18 has the center angle [θb / 2] at the rotational position detection mark 56. It is moved in the first direction by a distance corresponding to (1/2 of the circumferential length (width dimension)) (step S27).
Thereafter, the movement of the carriage 18 is stopped, and the linear light source 18a is turned off (step S28). As a result, the image sensor 18b is positioned at the home position HP. When the image sensor 18b is positioned at the home position HP, the process proceeds to step S31, and shading correction control of the linear light source 18a is executed.

In step S24, if the luminance level of the signal output from the image sensor 18b does not change to the black level even when the carriage 18 is moved by a preset distance in the first direction, the initial position of the carriage 18 is determined. Is determined to be located in the first direction (downstream direction in the document conveying direction) with respect to the rotating body 51, and the carriage 18 is moved in the second direction.
Thereafter, when the luminance level of the signal output from the image sensor 18b changes to the black level (“YES” in step S26), the processing is executed in the order of steps S27 and S28. As a result, the carriage 18 is positioned at the home position HP. Thereafter, the process proceeds to step S31, and shading correction control of the linear light source 18a is executed.

Next, the shading correction control executed after step S31 will be described.
In step S31, the linear light source 18a is turned on with the rotator 51 as the shading correction position where the correction reference surface 55 faces the first document glass 13. In this case, since the carriage 18 is positioned at the home position HP or in the initial area FA, the light emitted from the linear light source 18a is reflected on the correction reference plane of the rotator 51. The light is reflected by 55 and received by the image sensor 18b. From the image sensor 18b, a signal corresponding to the amount of reflected light from the correction reference surface 55 is output, and shading correction is performed so that the output is uniform on the average along the longitudinal direction of the linear light source 18a. Is implemented (step S32).

When the shading correction is completed, the rotating body 51 is set to the standard position (step S33). Thereby, the initialization control executed when the power is turned on ends.
By such initialization control, the carriage 18 is in a state of being located at a predetermined home position HP below the rotating body 51 or in a state of being in the initial area FA. 51f is a standard position facing the first original glass 13.

  Accordingly, when an image of a document conveyed by the ADF unit 40 is subsequently read by the image sensor 18b by the sheet through method, an operation for reading the image of the document can be immediately executed. When the carriage 18 is positioned in the initial area FA, the reading start timing of the document image by the image sensor 18b is corrected based on the reading timing correction time stored in the storage unit. As a result, the image of the document conveyed on the first document glass 13 can be read appropriately.

When one original passes through the first original glass 13 and the reading of the original image is completed, the rotary body 51 of the rotary member 50 is rotated once in the direction indicated by the arrow E by the rotary motor 53. When the rotating body 51 makes one rotation, the cleaning brush 52 slides on the first original glass 13 to remove foreign matters such as paper dust on the first original glass 13.
When an image of a document placed on the second document glass 16 is read by the moving optical method, the carriage 18 in the state positioned at the home position HP or in the initial area FA is moved in the first direction. Moved. During this movement, the original placed on the second original glass 16 is irradiated with light from the linear light source 18a to read the image of the original.

Also in this case, when the carriage 18 is positioned in the initial area FA, the reading start timing of the original image by the image sensor 18b is corrected based on the reading timing correction time stored in the storage unit. Thereby, the image of the document placed on the second document glass 16 can be read appropriately.
As described above, in the present embodiment, it is possible to specify in a short time whether the carriage 18 is located in the home position HP, the initial area FA, or the detection range RA. In addition, when the carriage 18 is located in the home position HP or the initial area FA, it is not necessary to move the carriage, so that the time required for initialization control can be further shortened.

[Modification]
In the above embodiment, the image sensor 18b is mounted on the carriage 18 and the image sensor 18b is moved together with the carriage 18. However, the present invention is not limited to this configuration, and the image sensor 18b is mounted on the carriage 18. Instead, the image reading apparatus A may be fixed at a predetermined position. In this case, a first carriage on which a linear light source and one mirror are mounted and a second carriage on which a pair of mirrors are mounted are provided, and light emitted from the linear light source and reflected from the document. Is reflected by a pair of mirrors of the first carriage and a pair of mirrors of the second carriage, and is received by a fixed image sensor 18b through an optical path having a certain length.

In addition, the configuration is such that the initialization control executed when the MFP apparatus is turned on is executed. However, the present invention is not limited to such a configuration, and also when a print job is instructed after the MFP apparatus is turned on. Alternatively, the initialization control may be executed. Alternatively, the initialization control may be executed only when a print job is instructed.
Further, in the above-described embodiment, the MFP apparatus has been described as the image forming apparatus provided with the image reading apparatus. However, the present invention is not limited to this and is also applicable to an image forming apparatus such as a copying machine or a facsimile. it can. Further, the image reading apparatus is not limited to the image forming apparatus, and may be an image reading apparatus having only an image reading function.

  INDUSTRIAL APPLICABILITY The present invention is useful as a technique for specifying the position of a light source unit in a short time in an image reading apparatus that reads an image of a document by a sheet through method and a moving optical method.

A image reading apparatus B image forming main body 10 image reading unit 13 first original glass 16 second original glass 18 carriage 18a linear light source 18b image sensor 40 ADF unit 50 rotating member 51 rotating body 51a flat surface 51b outer peripheral surface 51f guide surface 52 Cleaning brush 54 Rotation angle detector 55 Correction reference surface 56 Rotation position detection mark

Claims (11)

While moving the light source unit in the sub-scanning direction, the light from the light source unit is irradiated onto the stationary document, and the image reflected on the document is received by the imaging unit to read the image of the document. With the moving optical system and with the light source unit stationary at a position below the translucent member, the light emitted from the light source unit is applied to the document passing over the translucent member and reflected by the light source unit. An image reading apparatus capable of switching and executing a sheet-through method of reading an image of the document by receiving light by the imaging unit,
A rotating body disposed above the translucent member so as to be rotatable about a rotation axis parallel to a main scanning direction, and having an outer peripheral surface for guiding a document passing on the translucent member;
An optically readable mark provided on the outer peripheral surface of the rotating body;
Angle detection means for detecting a rotation angle of the rotating body;
The angle detection means when the reflected light from the mark of the light emitted from the light source unit in a stationary state is detected by the imaging means by rotating the rotating body when reading of the document image is not executed. Control means for identifying the position of the light source unit in the stationary state in the sub-scanning direction on the basis of the rotation angle detected in Step 1, and then controlling the document reading operation;
An image reading apparatus comprising:   When it is specified that the light source unit in a stationary state is located within a predetermined range below the translucent member, the control unit then determines the position where the light source unit is specified in the sheet-through method. 2. The image according to claim 1, wherein the reading operation of the original image is executed in a state where the light source is placed, and the reading operation is executed by starting the movement of the light source unit from the specified position in the moving optical system. Reader.   The control means starts reading by the imaging means at a predetermined timing when a subsequent document image reading operation is executed when it is specified that the light source unit is located at a reference position within the predetermined range. 3. The image reading apparatus according to claim 2, wherein when the position is deviated from the reference position, the reading start timing by the imaging unit is corrected based on the deviation.   When the mark is not detected by the imaging unit, the control unit positions the rotating body at a rotational position where the mark should be detected by the imaging unit if the light source unit is at a reference position. The light source unit is moved in the sub-scanning direction in a lighting state, and the light source unit is stopped at the reference position based on the position of the light source unit at the time when the mark is detected by the imaging unit. The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. A correction reference surface for shading correction is provided on the outer peripheral surface of the rotating body,
When it is specified that the light source unit is located within the predetermined range, the control unit moves the light source unit in a state where the correction reference plane is in a rotational position detected by the imaging unit. 5. The image reading apparatus according to claim 2, wherein shading correction is performed on the basis of the amount of light reflected from the correction reference surface of the light emitted from the correction reference surface.   The image reading apparatus according to claim 1, wherein the control unit executes a process of specifying a position of the light source unit when power is turned on.   The image reading apparatus according to claim 1, wherein the control unit executes a process of specifying the position of the light source unit when an instruction to read an image of a document is given.   8. The cleaning member according to claim 1, wherein the rotating member is provided with a cleaning member that slides and cleans the upper surface of the translucent member by the rotation of the rotating member. Image reading apparatus.   The image reading apparatus according to claim 1, wherein the imaging unit is movable together with the light source unit.   The image reading apparatus according to claim 1, wherein the imaging unit is fixed at a position where reflected light from a document can be received via a reflecting mirror.   An image forming apparatus comprising the image reading apparatus according to claim 1.

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