JP2005136593A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus having excellent image quality by solving the problem that deviation occurs at a reading seam portion of a composite image. <P>SOLUTION: The image reading apparatus is provided with a plurality of reading sensors 3 for dividing an original 11 in a carrying direction FD to read the original; a first roller 1 for feeding the original 11 to the reading sensors 3; a second roller 2 for discharging the original 11 from the reading sensors 3; first and second pressing rollers pressed on the first roller 1 and the second rollers 2, respectively; and a stepping motor (driving means) for rotating the first roller 1 and the second roller 2, by rotating the first and second pressing rollers. In this apparatus, the reading sensors 3 are each provided with a first reading sensor 31 and a second reading sensor 32, the both are provided at a distance L, and the external circumferential lengths of the first and second pressing rollers are each a positive integer multiple of the distance L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a plurality of reading units that divide and read a document in the conveyance direction, a first roller that feeds the document to the reading unit, and a second roller that feeds the document from the reading unit. The present invention relates to an image reading apparatus such as a scanner which is sent to a reading unit and then read by a second roller, and an image forming apparatus as a copying machine, a facsimile, a printer, or a complex machine including the image reading apparatus.

  As shown in FIG. 5, the conventional image reading apparatus includes a plurality of reading sensors (reading means) L that read a document T in the transport direction F on a document table R, and a first sensor that feeds the document T to the reading sensor L. 1 roller I, a second roller K for feeding the document T from the reading sensor L, an upper cover V, and the like.

The reading sensor L includes a contact glass M, an illumination unit N, a selfoc lens P, a light receiving element Q, and the like provided on the upper surface of the document table R. Image data read by the reading sensor L is an A / D conversion circuit. It is connected to the memory via. The upper cover V stores the first roller I and the second roller K. On the upstream side of the first roller I in the document T conveyance direction F, first document detection means S is provided, and on the downstream side in the conveyance direction F, second document detection means U that takes a reading start timing is provided.
In addition, a drive unit (not shown) that rotationally drives the first roller I and the second roller K and a drive control unit that controls the drive unit are provided.

Next, an operation for reading a document as image data by the document reading apparatus will be described.
By detecting the leading edge of the document T placed on the document table R by the first document detection means S, the image reading apparatus recognizes that the document T has been inserted, and moves the first roller I and the second roller K. Synchronous rotation is performed by a driving means (not shown). Then, the document T fed by the rotation of the first roller I is read by the reading sensor L. Specifically, a predetermined amount of light is applied to the reading surface TA of the document T by the illumination unit N inside the reading sensor L, and reflected light corresponding to the image pattern reflected from the reading surface TA is passed through the Selfoc lens P. Thus, an image is formed on the light receiving element Q at an equal magnification. The analog output level of the light receiving element Q corresponding to the image data is converted from analog to digital value by the A / D conversion circuit, and the converted image data is stored in the memory.
Then, the document T read by the reading sensor L is sent out of the apparatus by the second roller K.

  There are several types of reading sensors. FIG. 6A shows a reading sensor S1 having a length that can cover the maximum width of the document T, and a high-quality image can be obtained with a simple configuration. The reading sensor S1 needs to cover the entire width direction of the document. For example, in the case of a reading sensor capable of reading up to an A0 width document, the reading sensor S1 having a length of A0 is necessary, and the parts cost of the reading sensor S1 is increased. There is a problem that the cost of the image reading apparatus is increased.

  6B includes a reading sensor that is divided into a plurality of parts in the width direction of the document T. FIG. 6C described below is a reading sensor that uses an equal magnification type imaging element. FIG. 6B shows a method using reduction type reading sensors S31 and S32 using reduction lenses L1 and L2. In the figure, CG indicates contact glass. In FIG. 6B, compared with FIG. 6C, the reduction type reading sensors S31 and S32 are used, so that the manufacturing cost can be kept low. However, there is a problem that it is necessary to ensure a long optical path length between the reduction lenses L1 and L2 and the reading sensors S31 and S32, and the image reading apparatus is increased in size.

  Further, FIG. 6C shows a technique in which the reading sensors S21, S22, and S23 divided in the width direction are arranged in order to divide and read the document T in the transport direction, and the read image is synthesized by the control unit. Is disclosed (for example, Patent Document 1). According to this document, by arranging a plurality of reading sensors S21 to S23 having a short width, the component cost can be kept low. The component cost of the reading sensor is proportional to the length in the width direction. However, it is necessary to synthesize images read by a plurality of reading sensors S21 to S23, and there is a problem that image data processing becomes complicated.

  Specifically, first, as shown in FIGS. 7A and 7B, a part of the document T in the width direction is read as image data A by the reading sensors S21 and S23 provided on the upstream side in the document transport direction. Subsequently, an unread portion is read as image data B by a reading sensor S22 provided at a distance l away from the downstream side. At this time, the image data A read by the upstream reading sensors S21 and S23 is A / D converted, and then temporarily stored in a predetermined memory by the delay circuit, and the downstream reading sensor S22 by the distance l. The image data A and the image data B are combined at the reading joint portion J by the image combining unit in accordance with A / D conversion of the image data B read at the delayed timing.

Note that the position accuracy of each end of the reading sensors S21 to S23 is ensured so that a normal composite image can be obtained when the image data is combined. Further, with respect to the portion where the parts to which the reading sensors S21 to S23 are attached cannot be adjusted, the delay circuit and the like are adjusted to ensure the positional accuracy.
JP 59-105762 A

However, the rotation axis of the first roller I and the second roller K is not always on the rotation axis, and each rotation axis is, for example, a roller while the first roller I and the second roller K make one rotation. There may be a blur of about 0.05 mm for a diameter of 30 mm. This corresponds to about 0.17% when the distance 1 between the upstream side reading sensors S21, S23 and the downstream side reading sensor S22 is 30 mm, and the image shift amount Z due to this is about 50 μm. When reading at a resolution of 600 dpi (one dot is 42.3 μm), it is shifted by a little over one line, and it is technically difficult for the reading sensors S21 to S23 to normally combine the image data A and B. As shown in FIGS. 8A and 8B, there is a problem that a deviation occurs in the read joint portion J of the composite image.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus with good image quality.

The invention according to claim 1 includes a plurality of reading means for reading a document by dividing it along the conveyance direction;
A first roller for feeding the document to the reading means;
A second roller for feeding the original from the reading means;
A first pressing roller and a second pressing roller respectively pressed against the first roller and the second roller;
An image reading apparatus comprising: a driving unit configured to rotate the first roller and the second roller by rotating the first pressure roller and the second pressure roller.
The reading means includes a first reading means and a second reading means, both of which are provided with a distance L therebetween, and the outer peripheral lengths of the first pressing roller and the second pressing roller are respectively equal to the distance L. It is an integral multiple of.

  According to the first aspect of the present invention, the reading means includes the first reading means and the second reading means, both of which are provided at a distance L, and the first roller and the second roller are respectively pressed by the first pressure. Since the outer peripheral lengths of the first pressure roller and the second pressure roller are each a positive integer multiple of the distance L, the first pressure roller and the second pressure roller are rotated. Even if the axis is shaken, the synthesized image is not affected.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, a first intermediate roller is provided between the first roller and the first pressing roller, and the second roller and the second roller are provided. A second intermediate roller is provided between the pressing roller.

  According to the second aspect of the present invention, the first intermediate roller is provided between the first roller and the first pressing roller, and the second intermediate roller is provided between the second roller and the second pressing roller. When the diameters of the first pressure roller and the second pressure roller are reduced in accordance with L, even when the surfaces of the first pressure roller and the second pressure roller are coated with resin or the like, wear due to an increase in the rotational speed is caused. To reduce.

  According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the driving unit causes the first pressure roller and the second pressure roller to be driven and rotated, and the first pressure roller. And a belt is wound around the outer periphery of each of the second pressing rollers.

  According to the third aspect of the present invention, either the first pressure roller or the second pressure roller is driven to rotate by the driving means, and the belt is wound around the first pressure roller and the second pressure roller. Therefore, even if there is a subtle difference in the outer peripheral length of each of the first pressure roller and the second pressure roller, the rotation of either the first pressure roller or the second pressure roller is driven via the belt to the other pressure roller. By making the linear velocity of the first pressing roller and the linear velocity of the second pressing roller the same, the linear velocity of the first roller and the linear velocity of the second roller can be made the same. It is possible to prevent image displacement.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the image reading apparatus according to any one of the first to third aspects.

  According to the first aspect of the present invention, the reading unit includes the first reading unit and the second reading unit, both of which are provided at a distance L, and each of the first roller and the second roller is the first roller. The first pressure roller and the second pressure roller are rotated by being pressed by the first pressure roller and the second pressure roller, and the outer peripheral lengths of the first pressure roller and the second pressure roller are each a positive integer multiple of the distance L. Even if the rotation axis of the image is shaken, the rotation period of the rotation axis matches the distance L, so that the synthesized image is not shaken, and an image reading apparatus with good image quality can be provided.

  According to the second aspect of the present invention, the first intermediate roller is provided between the first roller and the first pressing roller, and the second intermediate roller is provided between the second roller and the second pressing roller. When the diameters of the first pressure roller and the second pressure roller are reduced according to the distance L, the surfaces of the first pressure roller and the second pressure roller are coated with urethane resin or the like for preventing slippage. Also, wear due to an increase in the rotational speed can be reduced.

  According to the third aspect of the present invention, since the belt is wound around the outer periphery of each of the first pressing roller and the second pressing roller, there is a slight difference in the outer peripheral length of each of the first pressing roller and the second pressing roller. Even so, it is possible to make the linear velocity of the first pressing roller and the linear velocity of the second pressing roller the same, to prevent the deviation of the composite image, and to provide an image reading apparatus with even better image quality. Can do.

  According to the invention described in claim 4, it is possible to provide an image forming apparatus including the document reading apparatus having the effect described in any one of claims 1 to 3.

1A and 1B are sectional views showing an example of the image reading apparatus of the present invention, and FIG. 2 is a plan view of the image reading apparatus.
The image reading apparatus includes a plurality of reading sensors (reading means) 3 that divides and reads a document 11 along a conveyance direction F on a document table 8, a first roller 1 that feeds the document 11 to the reading sensor 3, and a document 11. Is provided with a second roller 2 that feeds the sensor 2 from the reading sensor 3.

  In the reading sensor 3, the first reading sensor 31 and the second reading sensor 32 are arranged in a staggered manner at a distance L in a direction orthogonal to the document conveyance direction FD. The two first reading sensors 31 are arranged at the reading position on the same reading line 51. The reading sensors 31 and 32 are each provided with illumination means, a Selfoc lens, a light receiving element, and the like below the contact glass 4 provided on the upper surface of the document table 8, and image data read by the reading sensors 31 and 32. Are connected to a memory via an A / D conversion circuit.

A first document detecting means 9 is provided above the document table 8 and upstream of the first pressing roller 1D in the conveying direction F, below the contact glass 4 and in the conveying direction F of the first pressing roller 1D. On the downstream side, a second document detection means 10 is provided which takes a reading start timing.
Further, below the first reading sensor 31 and the second reading sensor 32, a stepping motor (driving means) 16 having a driving shaft 16D provided with a pulley 16a is provided, and the pulley 16a and the first pulley 14 of the first pressing roller 1D are provided. The timing belt 17 is wound around the second pulley 15 of the second pressing roller 2D, and the driving of the stepping motor 16 is transmitted to the first pressing roller 1D and the second pressing roller 2D.

The stepping motor 16 is rotationally controlled by drive control means (not shown). Further, the first roller 1 is pressed against and is in contact with the first pressing roller 1D by a compression spring or the like, and the former is rotated with the latter driving force. Similarly, the second roller 2 is also rotated by the driving force of the second pressing roller 2D pressed by a compression spring or the like.
Here, in this example, the diameters of the first pressure roller 1D and the second pressure roller 2D are determined so that the outer peripheral lengths of the first pressure roller 1D and the second pressure roller 2D are each a positive integer multiple of the distance L. doing.

Next, an operation for reading a document as image data by the document reading apparatus will be described.
By detecting the leading edge of the document 11 placed on the document table 8 by the first document detection means 9, the image reading apparatus recognizes that the document 11 has been inserted, and the stepping motor 16 is driven to drive the timing belt. The driving force is transmitted to the first reading roller 1D and the second reading roller 2D via 17. As a result, the first roller 1 and the second roller 2 are rotated.

  Then, the image data G1 and G2 of the document 11 sent between the first roller 1 and the first reading roller 1D onto the contact glass 4 are first read by the two reading sensors 31 on the reading line 51. Specifically, a predetermined amount of light is applied to the reading surface 11A of the document 11 by illumination means inside the reading sensor 31, and reflected light corresponding to the image pattern reflected from the reading surface 11A is received via the SELFOC lens. An image is formed at the same magnification on the element. The analog output levels of the light receiving elements corresponding to the image data G1 and G2 are converted from analog to digital signals (256 gradations) by the A / D conversion circuit and stored in the memory for a predetermined time by a delay circuit (not shown).

Similarly, the image data G3 of the document 11 is read by the reading sensor 32 on the reading line 52, converted from analog to digital value by the A / D conversion circuit and output, and a predetermined time has passed since passing through the first reading sensor 31. Thereafter, the image data G1 to G3 are combined into one line by the image combining unit and sent to an image processing circuit (not shown) on the downstream side.
On the other hand, the document 11 which has been read by the reading sensors 31 and 32 is sent out of the apparatus through the space between the second roller 2 and the second pressing roller 1D.

  Note that the first roller 1 and the second roller 2 used in the image reading apparatus have been conventionally provided with the second roller 2 so as not to cause a reading defect due to wrinkles when the document 11 is conveyed through the reading sensor 3. The diameter is slightly larger than the diameter of the first conveying roller 1, the linear velocity LV2 of the second roller 2 is made larger than the linear velocity LV1 of the first roller, and tension is applied to the document 11 by the pulling effect of the second roller 2. It is transported while. The same applies to this embodiment. The diameter of the first roller 1 is Φ30 mm, and the diameter of the second roller 2 is Φ30.05 mm. That is, the diameter of the second roller 2 is about 0.17% larger than the diameter of the first roller 1. The diameter of the first roller 1 and the diameter of the second roller 2 are not limited to this.

  By the way, the diameters of the first pressure roller 1D and the second pressure roller 2D are determined so that the outer peripheral lengths of the first pressure roller 1D and the second pressure roller 2D are each a positive integer multiple of the distance L as in this example. In this case, for example, if the distance L = 30 mm, the diameter Φ = 9.55 mm of the first pressing roller 1D and the second pressing roller 2D, the diameter of the first roller 1 is Φ30 mm, and the diameter of the second roller 2 is Φ30. If it is 05 mm, it becomes smaller than these, and the positional relationship with the guide plate (not shown) and the configuration of the conveyance system are complicated when the document 11 is conveyed between the first roller 1 and the first pressing roller 1D. There is a problem of becoming.

  In addition, the number of rotations of the first pressure roller 1D and the second pressure roller 2D during operation of the image reading apparatus increases, and the wear of the surfaces of the first pressure roller 1D and the second pressure roller 2D becomes more severe than in the past. There is also a problem that the durability is deteriorated and the surface of the first pressing roller 1D and the second pressing roller 2D becomes very dirty.

  Therefore, as shown in FIGS. 3A and 3B, a first intermediate roller M1 having substantially the same diameter as the first roller 1 is provided between the first roller 1 and the first pressing roller 20, and the second Between the roller 2 and the second pressing roller 21, a second intermediate roller M2 having substantially the same diameter as the second roller 2 is provided. Then, the first pressing roller 20 and the second pressing roller 21 having a diameter Φ = 9.55 mm are pressed so as to press the first roller 1 and the second roller 2 through the first intermediate roller M1 and the second intermediate roller M2. The first intermediate roller M1 and the second intermediate roller M2 are pressed by a compression spring (not shown), respectively.

  Further, the timing belt 24 is wound around the first driving pulley 22 of the first pressing roller 20, the second driving pulley 23 of the second pressing roller 21, and the pulley 16 a of the stepping motor 16.

  The image reading apparatus configured as described above transmits the driving force of the driving shaft 16D of the stepping motor 16 to the first pressing roller 20 and the second pressing roller 21 via the timing belt 24 wound around the pulley 16a. At this time, since the first pressing roller 20 and the second pressing roller 21 are formed with the same diameter (for example, Φ = 9.55 mm), they have the same linear velocity. Then, the rotation is transmitted to the first intermediate roller M1 and the second intermediate roller M2 by the pressing force, respectively. Further, the rotation is transmitted to the first roller 1 and the second roller 2 pressed by the compression springs to the first intermediate roller M1 and the second intermediate roller M2.

  In such an image reading apparatus, the first roller 1 and the first intermediate roller M1 have substantially the same diameter, and the second roller 2 and the second intermediate roller M2 have substantially the same diameter. The configuration is not complicated. Therefore, the document 11 is smoothly conveyed without clogging the paper.

  In addition, even if blurring occurs as the first roller 1 and the second roller 2 rotate, the rotation cycle of the first roller 1 and the second roller 2 is the first pressing roller 20 and the second pressing roller 21 that are driving rollers. Since the distance L is an integral multiple of the outer circumference of the first pressing roller 20 and the second pressing roller 21, the distance between the first pressing roller 20 and the second pressing roller 21 is the same. Even when there is a blur on the rotation axis, the image data G1 to G3 read by the first reading sensor 31 and the second reading sensor 32 can be combined without shifting without affecting the reading of the image.

  However, in this example, since both the first pressing roller 20 and the second pressing roller 21 are driving rollers, either or both of the outer circumferences of the first pressing roller 20 and the second pressing roller 21 are integers of the distance L. When there is a slight difference, the rotation is transmitted to the first roller 1 and the second roller 2 via the first intermediate roller M1 and the second intermediate roller M2, and the first pressure roller 20 There is a problem that a shift according to the rotation of the rotation axis of the second pressing roller 21 is transmitted to the first roller 1 and the second roller 2 to cause a shift when the image data G1 to G3 are combined.

  Therefore, as shown in FIGS. 4A and 4B, either the first pressing roller 20 or the second pressing roller 21 is main-rotated by the stepping motor 16 (in this example, only the second pressing roller 21 only). Stepping motor 16 and timing belt 25 are connected to form a driving roller.) And only second pressing roller 21 that wraps the belt around the outer periphery of each of first pressing roller and second pressing roller is stepped. The motor 16 and the timing belt 25 are connected to form a driving roller. Then, a flat belt (belt) 26 is wound between the first pressing roller 20 and the second pressing roller 21, and the first pressing roller 20 is rotated by driving the second pressing roller 21.

  With such a configuration, the linear speed of the second pressing roller 21 is transmitted to the first pressing roller 20 and becomes the same speed. Therefore, the first roller is interposed via the first intermediate roller M1 and the second intermediate roller M2. 1 and the linear velocity of the 2nd roller 2 can be made the same, and a still more blurred image can be provided. Further, only the outer periphery of the second pressing roller 21 needs to be accurately manufactured so as to be an integral multiple of the distance L, and the manufacturing process can be simplified. In this example, the main driving roller is the second driving roller 21, but the present invention is not limited to this and may be the first driving roller 20.

1 is a schematic cross-sectional view of a main part of an image forming apparatus provided with a document reading apparatus of the present invention. It is a principal part expanded sectional view of FIG. FIG. 3 is a schematic plan view of FIG. 2. (A)-(c) is a principal part schematic diagram of the conventional image reading apparatus. (A) is a diagram showing an operation flow at the time of image reading in the image reading apparatus of FIG. 4 (b), and (b) is a diagram showing a deviation of image data caused thereby. FIGS. 5A and 5B are examples of specific misalignment by the conventional image reading apparatus of FIG. 5, in which FIG. 5A shows an example of image data misalignment when the document enters the second roller, and FIG. 5B shows the rear end from the first roller. It is an example which shows gap of image data when it leaves. (A) is a flowchart for synthesizing the read image data, and (b) is a diagram showing how the image data is disturbed when the read image data is synthesized. (A), (b) is the figure which showed a mode that the image shifted | deviated in the reading seam part when synthesize | combining image data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st roller 1a axis | shaft 1D 1st drive roller 2 2nd roller 2D 2nd drive roller 3 Reading sensor (reading means)
4 Contact glass 5 Illumination means 6 Selfox lens 7 Light receiving element 8 Document table 9 First document detection means 10 Second document detection means 11 Document 11a Reading surface 13 Thick plate 14 First pulley 15 Second pulley 16 Stepping motor 16a Pulley 16D Drive shaft 17, 24, 25 Timing belt 20 First pressing roller 21 Second pressing roller 22 First driving pulley 23 Second driving pulley 26 Flat belt (belt)
31 First reading sensor (reading means)
32 Second reading sensor (reading means)
51, 52 Reading line FD Document conveying direction L Distance M1 First intermediate roller M2 Second intermediate roller

Claims (4)

A plurality of reading means for dividing and reading a document along the conveyance direction;
A first roller for feeding the document to the reading means;
A second roller for feeding the original from the reading means;
A first pressing roller and a second pressing roller respectively pressed against the first roller and the second roller;
An image reading apparatus comprising: a driving unit configured to rotate the first roller and the second roller by rotating the first pressure roller and the second pressure roller.
The reading means includes a first reading means and a second reading means, both of which are provided with a distance L therebetween, and the outer peripheral lengths of the first pressing roller and the second pressing roller are respectively equal to the distance L. An image reading apparatus characterized by being an integral multiple of.   The first intermediate roller is provided between the first roller and the first pressing roller, and the second intermediate roller is provided between the second roller and the second pressing roller. The image reading apparatus described in 1.   One of the first pressing roller and the second pressing roller is driven to rotate by the driving means, and a belt is wound around the outer periphery of each of the first pressing roller and the second pressing roller. The image reading apparatus according to claim 2. An image forming apparatus comprising the image reading apparatus according to claim 1.

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