JP2007153580A - Document reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of keeping image quality regardless of the thickness and a kind of sheet document. <P>SOLUTION: A stepping motor 301 rotates according to the input step number in response to the paper thickness of the sheet document 400, and an eccentric cam 302 moves a document carrier roller 205 up to a predetermined position by rotating at a predetermined angle by rotation of the stepping motor 301, and a document inserting roller 203 carries the sheet document 400 up to a document reading position. When the sheet document 400 is carried up to a position of the document carrier roller 205, the sheet document 400 passes through a position corresponding to the paper thickness of the sheet document 400 by the document carrier roller 205, and at the same time, a document reading part 105 illuminates the sheet document 400 by a light source 102, and its reflected light is imaged on an image sensor 104 by a Selfoc lens array 103, and an image signal is taken out as an electric signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an original reading apparatus used for reading an original in an image forming apparatus such as a copying machine, a scanner, or a facsimile, and more particularly to an original reading apparatus of a type that conveys a sheet original.

FIG. 6 shows a schematic configuration of a conventional sheet document conveyance type image reading apparatus.
6 includes a contact glass 1, a light source 2, a selfoc lens array 3, a document reading unit 5 including an image sensor 4, driven rollers 6 and 7, a document transport roller 8, a document insertion transport roller 10, and a document. A discharge conveying roller 9 is provided. The sheet document 30 to be read is conveyed by rotating the document insertion / conveyance roller 5 in the direction of the arrow in the drawing by a driving unit (not shown). The sheet original 30 is illuminated by the light source 2 while being conveyed, the reflected light is imaged on the image sensor 4 by the SELFOC lens array 3, and the image signal is taken out as an electric signal.

In addition, as a device for transporting thick paper sheets, the paper transport speed is reduced when the leading edge of the thick paper sheet enters the document discharge transport roller disposed on the rear side in the transport direction, and the document disposed on the front side in the transport direction. Patent Document 1 discloses an invention for solving the problem that a reading image expands and contracts because a phenomenon that the document conveying speed is accelerated when the trailing edge of the sheet document comes off from the insertion conveying roller. ing.
JP 2001-48374 A

  In the document reading device of Patent Document 1, a driven roller is provided so as to be movable in a direction in which it is in contact with and away from the document transport roller. Displacement means for changing the interval is provided. The displacing means is rotatably provided at one end of a swingable arm with a pin as a rotation shaft on the driven roller, and pressurizes the document insertion transport roller and the document discharge transport roller by biasing the arm by a spring. It is a thing. The arm is linked by fitting the protrusion at the upper end into the hole of the link.

  When the driven roller is pushed upward by the sheet document and the arm swings, this movement is transmitted to the arm via the link, and the arm also swings, and the driven roller is displaced in a direction away from the document discharge conveyance roller. . By this interlocking operation, the force acting in the direction opposite to the original conveying direction generated when the thick sheet original enters the original discharge conveying roller is reduced. As a result, reading without image expansion can be performed without reducing the speed of the sheet document.

  However, the document reading apparatus disclosed in Patent Document 1 is a method in which the contact glass and the sheet document are in close contact with each other, and since the printing portion of the sheet document is in direct contact with the contact glass, the contact glass is easily soiled and the image quality is deteriorated. Therefore, the operation | work of cleaning a contact glass regularly will generate | occur | produce.

  In the configuration shown in FIG. 4, the contact glass 1 and the sheet document 30 have a certain width, and the document is read without contacting the contact glass 1 and the sheet document 30. In the document reading method in which the contact glass 1 and the sheet document 30 are not in contact with each other, the image quality is affected when the sheet document 10 is not at the position where the focal depth of the SELFOC lens array 3 is optimum, and the sheet document is affected. The focal length of the SELFOC lens array 3 is affected by the thickness and type of 30.

  SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus capable of maintaining image quality regardless of the thickness and type of a sheet document.

  In order to achieve the above object, the document reading apparatus according to claim 1 has a plurality of document conveying rollers and a driven roller, sandwiches the document with a plurality of document conveying rollers and a driven roller that is driven to rotate, and performs exposure scanning. The document reading apparatus includes a selection unit that can select a paper thickness type of the document, and an adjustment unit that adjusts the vertical position of the document transport roller according to the paper thickness type selected by the selection unit. .

  According to a second aspect of the invention, there is provided the original reading apparatus according to the first aspect, further comprising storage means for storing the vertical position of the original conveying roller corresponding to the type of paper thickness, and the adjustment means is stored in the storage means. The vertical position of the document conveying roller corresponding to the type of paper thickness selected by the selection unit is determined based on the information that has been selected, and the vertical position of the document conveying roller is adjusted to be the determined vertical position. It is a means to do.

  The invention according to claim 3 is the document reading apparatus according to claim 1 or 2, wherein the adjusting means includes an eccentric cam and a driving means for driving the eccentric cam, and the eccentric cam and the driving means are the document conveying rollers. The drive means is an eccentric cam so that the document conveying roller corresponding to the type of paper thickness selected by the selection means based on the information stored in the storage means is at a predetermined vertical position. Is rotated at a predetermined angle.

  According to a fourth aspect of the present invention, there is provided the original reading apparatus according to the first or second aspect, further comprising paper thickness detecting means for detecting the paper thickness of the original, and the adjusting means is an eccentric cam and a drive for driving the eccentric cam. The eccentric cam and the driving means are provided below the original conveying roller, and the driving means is a vertical direction of the original conveying roller stored in the storing unit and the paper thickness of the original detected by the paper thickness detecting means. Based on the position, the eccentric cam is rotated at a predetermined angle so that the document conveying roller is at a predetermined vertical position.

  According to a fifth aspect of the present invention, there is provided the original reading apparatus according to the fourth aspect, wherein the paper thickness detecting means includes a pressure detecting means provided on an upper portion of the driven roller, and the original is a plurality of original conveying rollers and a driven roller. When the paper is sandwiched and conveyed, the pressure detection means detects the pressure when the driven roller is pushed upward by the paper thickness of the original, thereby detecting the paper thickness of the original.

  The invention according to claim 6 is the document reading apparatus according to any one of claims 1 to 5, wherein the adjustment means determines the reference position of the eccentric cam and the rotation position when rotated at a predetermined angle. It is characterized by detecting.

  According to the present invention, it is possible to read a document in accordance with an optimum depth of focus regardless of the thickness of the document, and to maintain a constant image quality.

Next, the invention according to this embodiment will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a document reading apparatus according to the present embodiment.
The document reading apparatus 100 includes a document reading unit 105, driven rollers 201 and 202, a document insertion transport roller 203, a document discharge transport roller 204, a document transport roller 205, and a cam mechanism 300. The document reading unit 105 includes a contact glass 101, a light source 102, a selfoc lens array 103, and an image sensor 104. The cam mechanism 300 includes a stepping motor 301, an eccentric cam 302, an actuator 501, and a position sensor 502.

FIG. 2 is a block diagram illustrating a configuration of the document reading apparatus 100 according to the present embodiment.
The document reading apparatus 100 includes a control unit 601, a ROM 602, a RAM 603, an operation unit 604, an image processing unit 605, an image storage unit 606, a driving unit 607, a document reading unit 105, and a position sensor 502.

  A control unit 601 controls the entire document reading apparatus 100. The ROM 602 stores a program executed by the control unit 601. The RAM 603 stores various parameters necessary for control. The operation unit 604 includes various operation keys and a display unit. Here, the operation unit 604 includes, as various operation keys, a paper thickness selection key that can select the paper thickness of the original, a reset key that selects the paper thickness, and returns the print density to the initial setting (FIG. 5). Not shown). For example, the operation keys can select the paper thickness such as “thick”, “normal”, and “thin”, and the user selects the paper thickness of the sheet document 400 to be copied from the paper thickness selection key. An image processing unit 605 performs scaling, rotation, erasure, composition, and the like of image data. The image storage unit 606 stores image data. The drive unit 301 transmits a signal for driving the stepping motor 301 of the cam mechanism 300. The document reading unit 105 reads the sheet document 400, and the position sensor 502 detects the position of the eccentric cam 302 from the position of the actuator 501.

  When the user copies the sheet document 400, first, when a key corresponding to the sheet thickness of the sheet document is pressed from the paper thickness selection operation key in the operation unit 604, a predetermined signal is sent from the operation unit 604 to the drive unit 607. The drive 607 rotates the stepping motor 301 of the cam mechanism 300 so that the eccentric cam 302 rotates. When the eccentric cam 302 rotates a predetermined rotation angle, the document conveying roller 205 moves vertically to a position corresponding to the paper thickness selected by the operation unit 604.

  In the present embodiment, the position of the document conveying roller 205 that moves in the vertical direction according to the sheet thickness of the sheet document 400 is specified by detecting the rotational position of the eccentric cam 302. In order to detect the rotational position of the eccentric cam 302, an actuator 501 and a position sensor 502 are provided. The position sensor 502 includes a pair of arm portions, and the presence of the actuator 502 is detected when the actuator 501 is positioned between the arm portions.

  Since the stepping motor 301 rotates based on the input signal, it is possible to control the rotational angle that is the driving amount and the rotational position of the eccentric cam 302 based on the rotational angle based on the number of input steps. When the eccentric cam 302 is in the initial position, this position is stored in the RAM 603, and the rotational position of the eccentric cam 302 is detected in an arbitrary state based on the number of steps from this position, and the eccentric cam 302 is rotated. The reference position can be specified.

FIG. 3 shows how the eccentric cam 302 rotates.
The position of the actuator 501 in the position sensor 502 changes as the eccentric cam 302 rotates. As shown in FIG. 3A, the initial position is set when the position of the actuator 501 in the position sensor 502 is a. The RAM 603 stores an initial position of the actuator 501, a position detected by the type of paper thickness, and the number of steps for rotating the eccentric cam 303 by a predetermined angle.

Next, FIG. 3B shows a state where the document transport roller 205 has moved to a position corresponding to the paper thickness selected by the operation unit 604.
When the user presses the paper thickness selection key provided in the operation unit 604, the driving unit 607 inputs the number of steps corresponding to the selected paper thickness type stored in the RAM 603 to the stepping motor 301. The stepping motor 301 rotates in accordance with the input number of steps, and the eccentric cam 302 rotates at a predetermined angle by the rotation of the stepping motor 301.

  When the document transport roller 205 moves to a predetermined position, the document insertion roller 203 transports the sheet document 400 to the document reading position (in the direction of arrow B in FIG. 1). When the sheet document 400 is conveyed to the position of the document conveying roller 205, the sheet document 400 passes the position corresponding to the paper thickness of the sheet document 400 by the document conveying roller 205, and at the same time, the document reading unit 105 has the light source 102. Then, the sheet original 400 is illuminated, the reflected light is imaged on the image sensor 104 by the SELFOC lens array 103, and the image signal is taken out as an electric signal.

  Also, if the rotation angle of the eccentric cam 302 corresponding to the type of paper thickness and the position of the actuator 501 in the position sensor 508 are different, it is considered that the operation is abnormal, and the eccentricity is set so that the actuator 501 is at the initial position. The cam 302 is rotated (FIG. 3C).

  The document transport roller 205 moved in the vertical direction does not return to the initial position (FIG. 3A) until the copy operation of the sheet document 400 is completed or until the reset key on the operation unit 504 is pressed. And

Next, with reference to FIGS. 4 and 5, the operation of detecting the sheet thickness of the sheet document by the document reading apparatus will be described.
As shown in FIG. 4, the driven roller 201 provided immediately above the document insertion conveyance roller 203 is provided with a spring 206 and a pressure sensor 207. When the sheet document 400 is inserted between the document insertion conveyance roller 203 and the driven roller 201, the driven roller 201 moves in the direction of arrow C depending on the thickness of the sheet document 400. At the same time as the driven roller 201 moves in the direction of arrow C, the spring 206 contracts. The pressure sensor 207 can detect the contraction of the spring 206 at this time, and measures the paper thickness of the sheet document 400 from the contraction of the spring detected by the pressure sensor 207.

  The driving unit 607 inputs a predetermined number of steps to the stepping motor 301 based on the measured value of the sheet thickness of the sheet original 400 measured by the pressure sensor 207, and the eccentric cam 302 rotates by a predetermined angle by the rotation of the stepping motor 301. Thus, the document conveying roller 205 is moved to a position suitable for the sheet thickness of the sheet document 400.

  When inputting a predetermined number of steps from the measured value of the sheet thickness of the sheet document 400 obtained by the pressure sensor 207 to the stepping motor 301, the driving unit 607 selects the sheet thickness in which the measured value of the sheet thickness is stored in the RAM 603. Compare the paper thicknesses selected by the key. For example, when the measured value of the paper thickness is close to the paper thickness corresponding to “thick” of the paper thickness selection key, the driving unit 607 moves to the position corresponding to “thick” of the paper thickness selection key. Move.

  Further, when measuring the paper thickness, as shown in FIG. 4B, when the leading edge of the sheet document 400 is conveyed to the document insertion roller 203, the document insertion conveyance roller 203 and the driven roller 201 are measured. In some cases, the entire sheet document 400 is passed between the two.

  When measuring the paper thickness at the front end portion of the sheet original 400, the pressure sensor detects the paper thickness of the sheet original 400 when the sheet original 400 passes between the original insertion conveyance roller 203 and the driven roller 201. Then, before the sheet original 400 passes the position of the original reading unit 105, the original conveying roller 205 is moved to a position corresponding to the detected paper thickness.

  When the entire sheet document 400 is passed, the entire sheet document 400 passes between the document insertion conveyance roller 203 and the driven roller 201, and the sheet document 400 is discharged once by the document carry-out conveyance roller 204. To do. Then, the sheet original 400 is conveyed once again and a reading operation is performed.

  From the above description, according to the present embodiment, since the original can be read with the optimum depth of focus regardless of the thickness of the original, a constant image quality can be maintained. Further, since the thickness of the original can be selected by the user, or the thickness of the original can be measured before the original is read, it is possible to deal with various kinds of originals.

1 is a diagram illustrating a configuration of a document reading apparatus according to an embodiment. 1 is a block diagram illustrating a configuration of a document reading apparatus according to an embodiment. It is the figure which showed the operation | movement of the cam mechanism shown in FIG. It is the figure which showed the mechanism which detects paper thickness. It is a block diagram which shows the mechanism which detects the paper thickness shown in FIG. FIG. 10 is a diagram illustrating a configuration of a conventional document reading apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Document reading apparatus 101 Contact glass 102 Light source 103 Selfoc lens array 104 Image sensor 105 Document reading part 201,202 Followed roller 203 Document insertion conveyance roller 204 Document discharge conveyance roller 205 Document conveyance roller 206 Spring 207 Pressure sensor 300 Cam mechanism 301 Stepping Motor 302 Eccentric cam 400 Sheet document 501 Actuator 502 Position sensor 601 Control unit 602 ROM
603 RAM
604 Operation unit 605 Image processing unit 606 Image storage unit 607 Drive unit

Claims (6)

A plurality of document conveying rollers and driven rollers;
In a document reading apparatus that sandwiches a document between the plurality of document conveying rollers and the driven roller that is driven to rotate, and performs exposure scanning,
A selection means capable of selecting a paper thickness type of the document;
An original reading apparatus, comprising: an adjusting unit that adjusts a vertical position of the original conveying roller according to a type of paper thickness selected by the selecting unit. Storage means for storing a vertical position of the document conveying roller corresponding to the type of the paper thickness;
The adjustment unit determines a vertical position of the document conveying roller corresponding to the type of paper thickness selected by the selection unit based on information stored in the storage unit, and determines the determined vertical direction position. 2. The document reading apparatus according to claim 1, wherein said document reading roller is a means for adjusting a vertical position of said document conveying roller. The adjusting means includes an eccentric cam and a driving means for driving the eccentric cam,
The eccentric cam and the driving means are provided below the document conveying roller,
The drive means moves the eccentric cam so that the document conveying roller corresponding to the type of paper thickness selected by the selection means is at a predetermined vertical position based on information stored in the storage means. 3. The document reading device according to claim 1, wherein the document reading device is rotated at a predetermined angle. Comprising paper thickness detecting means for detecting the paper thickness of the original;
The adjusting means includes an eccentric cam and a driving means for driving the eccentric cam,
The eccentric cam and the driving means are provided below the document conveying roller,
The drive means moves the document transport roller to a predetermined vertical position based on the paper thickness of the document detected by the paper thickness detection means and the vertical position of the document transport roller stored in the storage means. 3. The document reading apparatus according to claim 1, wherein the eccentric cam is rotated at a predetermined angle. The paper thickness detection means has a pressure detection means provided on the top of the driven roller,
When the document is conveyed while being sandwiched between the plurality of document conveying rollers and the driven roller,
5. The document reading apparatus according to claim 4, wherein the pressure detecting means detects the pressure of the original when the driven roller is pushed upward by the thickness of the original. .   6. The document reading apparatus according to claim 1, wherein the adjustment unit detects a reference position of the eccentric cam and a rotation position when the eccentric cam rotates at a predetermined angle. 7.

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