JPH09247392A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dust stuck to an original from sticking and accumulating at an original table by providing a mechanism of moving the original to an original reader. SOLUTION: The original table 70 is supposed to be deviated to the side of an entrance in the direction of carrying the original. When driving motors 71 are rotated by 180 deg. from this state, this rotation driving force is transmitted to the original table 70 through driving bodies 72, and driving pins 72a to move the original table toward the side of an exit in the direction of carrying the original. When the driving motors 71 is rotated by 180 deg. in addition, the original table moves back to the original position. In addition, without regard to whether the original is carried or not, the driving motors 71 is intermittently driven for a fixed time, etc., to move the original table 70 at an optional time by an optional amt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device, and is applicable to a reading unit of a scanner of a digital copying machine, a reading unit of a scanner for inputting an image, and a reading unit of a facsimile machine. Document reading device.

[0002]

2. Description of the Related Art An example of a conventional document feeding type reading apparatus will be described with reference to FIGS. In FIG. 9, reference numeral 64 indicates a backup roller, and reference numerals 65 and 65 indicate a pair of conveyance rollers. Reference numeral 66 indicates a lens, and reference numeral 67 indicates a reading element such as a CCD. As shown in FIG.
If the dust (rubber dust to be erased with about 0.2 mm to 1 mm or the like) 60 adhered on the document table 63 (generally called contact glass) 62 and stayed there, it was read. Straight black data appears on the original image data. Therefore, when the document 61 as shown in FIG. 10A is read, it is read as an image 68 as shown in FIG. 10B. Symbol 69
Indicates a black straight line (vertical line) generated due to dust adhering to the original 61. That is, the dust 60 is processed as black data on the image data obtained by reading the document 61, and as a result, the black straight line 69 appears on the image 68.

On the other hand, in the analog copying machine, there are a document moving type and an optical system moving type, both of which have a slit having a width of 5 to 10 mm (width of the exposure area in the moving direction of the document). It is exposed in the area. In this slit exposure area, the latent image is not formed on the photoconductor unless the original and the photoconductor move in synchronism, so even if the above-mentioned dust adheres and stays on the contact glass, the optical system movement type , The black spots correspond to the size of the dust, and the original moving type forms a blurred latent image, so that the image is developed without being affected by the attached dust.

[0004]

As described above, in the original moving type using the CCD as the reading element, the dust 60 adhering to the original 61 appears as a black straight line 69, which causes a remarkable deterioration of the reading quality. I will leave. This phenomenon is prominent in a document moving type digital scanner using a CCD. That is, in a document moving type digital scanner, for example, a commonly used reading density is 400 dpi (dots p).
read exposure width is 63.5μ
Since it is very narrow, m (= 25.4 / 400), if dust with a width of 63.5 μm or more (for example, eraser dust, hair, ink dust of electrostatic plotter, etc.) adheres to this portion and stays there. However, there is a problem in that the portion is continuously read as black data regardless of the image, and a black line 69 appears remarkably in the read image.

In the conventional example shown in FIG. 9, a backup roller 64 having a white surface is used as the reference reflecting plate for shading correction in the reading section 63, and the reflection density of the backup roller 64 is 0.03. ~ 0.08
(Reflectance is 93 to 83%). Since the backup roller 64 reads the image while pressing the document 61, the dust 60 attached on the document 61
Is the narrowest part between the backup roller 64 and the document table 62 (from the center line of the backup roller 64 to the document table 6).
There is a problem that it is strongly pressed against the document table 62 at a position where it is connected to the document table 2 by a perpendicular line) and adheres to the document table 62. In other words, since the document table 62 is fixed, there is a problem that the frequency of occurrence thereof increases.

The present invention has been made in order to solve the above-mentioned problems of the prior art. When the document is moved, the platen is moved in the moving direction of the document or in the direction perpendicular to the moving direction of the document. An object of the present invention is to provide a document reading apparatus that can reduce the frequency of dust adhering to the document table and prevent a significant reduction in reading quality.

[0007]

According to the first aspect of the present invention,
A pair of document conveying rollers for conveying various documents to the document reading unit, a one-dimensional reading element for converting an image on the document moving in the reading unit into an electrical signal, and a document illuminating unit for illuminating the document by the reading unit. In a document reading device having an illuminating device, a transparent document table provided in a recording unit, and a backup roller which is arranged to face the document table and rotates while pressing a document passing through the document table against the document table, It is characterized by having a mechanism for moving the document table.

According to a second aspect of the present invention, the platen is moved at an arbitrary time and by an arbitrary amount in a moving direction of the document, a direction perpendicular to the moving direction, or a direction in which the moving direction and the right direction are combined. It is characterized by being possible.

The invention according to claim 3 is characterized in that the document table can be manually moved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a document reading apparatus according to the present invention will be described below with reference to the drawings. In FIG. 5, an upper unit case 3 is supported above a document table 2 on which a document 1 is placed by a support shaft (fixed to a side plate of the main body structure of the document reading device) 4 so as to be vertically swingable. A transparent manuscript table 11 is arranged behind the manuscript table 2 (on the left side in FIG. 5), and lamps 13, 13 are provided below the manuscript table 11.
A lens 15 and a reading element 16 such as a one-dimensional CCD are arranged. On the other hand, above the document table 11, a backup roller 14 which is supported by the upper unit case 3 and rotates counterclockwise in FIG. 5 is arranged. On the right side of the original table 11, two original document conveying roller pairs 5 and 6 are arranged, while the original table 1 is provided.
One document conveying roller pair 7 is arranged on the left side of 1.

The original 1 on the original table 2 passes over the original table 11 while being conveyed from the right side to the left side in FIG. 5 by the pair of conveying rollers 5, 6, and 7, and at this time, the exposure (illumination) position. Illuminated by lamps 13, 13 at L. The reflected light from the document 1 illuminated by the lamps 13, 13 is condensed on the reading element 16 by the lens 15, and the image of the document 1 is read by the reading element 16.

In this case, when the original 1 is inserted into the original table 2 and the first sensor 17 provided near the original insertion opening of the upper unit case 3 detects the original 1, the original conveying roller pairs 5, 6 are provided. , 7 and the above backup roller 1
4 starts rotating, and the lamps 13, 13 light up. When the leading edge of the transported document 1 is detected by the second sensor 18 arranged behind the document transport roller pair 5,
The transport speed of the document 1 changes to the transport speed according to the preselected scaling factor. After that, when the leading edge of the original 1 is detected by the register sensor 19 arranged behind the original conveying roller pair 6, the backup roller 1 at the exposure position L is detected.
The reflected light from 4 is read by the reading element 16. The surface of the backup roller 14 is previously painted in white, and therefore the reflection density of the backup roller 14 is about 0.03 to 0.08 (reflectance 93 to 83%). The read reflected light data of the backup roller 14 is A / D converted and stored in the shading RAM as shading correction data.

Thereafter, the original 1 is conveyed on the original table 11 and is transferred through the gap between the original table 11 and the backup roller 14, while being illuminated by the lamps 13 and 13 at the exposure position L, The reflected light from the original 1 at this time is focused on the reading element 16 by the lens 15, and the image of the original 1 is reduced and focused on the reading element 16 and read. After that, the document 1 for which the reading and scanning has been completed is ejected to the paper ejection tray 20 by the document conveying roller pair 7.

The image data of the read original 1 includes the uneven light amount of the lamps 13 and 13 and the cos of the lens 15.
⁴ Decrease in light quantity due to the θ law, above reading device (CCD)
In order to compensate the sensitivity unevenness of each pixel of No. 6 and the like, the correction is performed based on the shading correction data.

Next, the upper unit case 3 will be described more specifically. The upper unit case 3 is provided with the document table 2 and the document table 11 at a predetermined angle about the axis 4.
Can be swung upwards to open the surface.
Therefore, by this opening, each document conveying roller pair 5, 6,
7. Maintenance work such as cleaning of the document table 2, the sensors 17, 18, 19 and the document table 11 and the like, processing of documents having trouble in conveyance, replacement of the lamps 13 and 13 and the like can be easily performed. Also, the illumination lamps 13, 1
3, the lens 15 and the reading element 16 are provided with a cover 21 to prevent dust from the outside. Reference numeral 22 indicates an optical axis described later.

The optical system will be described with reference to FIG.
As shown in FIG. 6, two sets of optical systems including the lens 15 are arranged along the main scanning direction of the original 1. Manuscript 1 above
The image information of 1 is read individually by the two reading elements 16. In FIG. 6, the lens 15 and the reading element 16 are arranged along the two optical axes 22 and 22, respectively. One half of the original 1 is read by one of the reading elements 16 and the other half is read by the other reading element 16 with the center point P in the main scanning direction as a boundary.

The document 1 is transported between the document table 11 and the backup roller 14. As will be described later, since the backup roller 14 is driven to rotate, if it comes into contact with the document table 11, the document table 11 will be damaged. In order to avoid this, as shown in FIG. 6, guide rollers 2 are provided at both axial end portions of the backup roller 14.
3, 23 are rotatably supported. The diameter of the guide rollers 23, 23 is set to be slightly larger than the diameter of the backup roller 14, so that a slight gap is formed between the backup roller 14 and the document table 11. Considering that the thickness of a normal sheet-shaped document is about 50 to 100 μm, for example,
It is set to a minute interval of about 0.1 to 0.2 mm.

Here, if the original 1 passing through the original table 11 has a curl or a fold, the original is pressed against the original table 11 by the backup roller 14 and becomes flat. And lens 1
5 and 5 are always held constant. As described above, since the original document does not float from the original table 11, the boundary point P between the adjacent optical systems at the illumination position of the original document is always held at a fixed position, so that the bit shift or the image between the images of the adjacent optical systems is maintained. Missing is prevented. Further, in FIG. 6, reference numerals 25 and 25 denote power transmission means for rotationally driving the backup roller 14.

Next, another embodiment will be described.
In FIG. 7, reference numeral 40 indicates a line connecting the rotation center of the backup roller 14 and the narrowest part of the backup roller 14 and the document table 11. Further, reference numeral 41 indicates a lens optical axis in this embodiment, and reference numeral 4
1.5 mm to the right of the 0 line (upstream side in the document transport direction)
It is located in. The remaining reference numerals are the same as those described in the above embodiment. Here, in the embodiment described in FIG. 5, the optical axis 22 (reference numeral 41 in FIG. 7) is used.
Is located at the narrowest part of the backup roller 14 and the document table 11, and this narrowest part is set to the reading position. Since dust is likely to adhere to this narrowest part, In the examples shown in FIGS. 7 and 8, the position where the narrowest part is avoided is set as the reading position.

As shown in FIG. 8, since the optical axis 41 is located on the right side by about 1.5 mm with respect to the line 40, and this portion is set as the reading position, it is possible to prevent dust from adhering. it can.

Next, an example of the original table applicable to the above embodiment will be described. In FIG. 1, reference numeral 70 indicates
The manuscript table is shown. The document table 70 is provided with circular holes 70a, 70a into which drive pins to be described later are fitted, and the holes 70a, 70a do not affect the transported document even if the document is transported. It is installed in the position. Reference numerals 72 and 72 denote driving bodies for moving the document table 70. The driving bodies 72, 72 have disks 72b, 72b having a certain thickness, cylinders 72c, 72c provided at the center of the lower part thereof, and drive pins 72a, 72a provided at the upper part. The pins 72a, 7
2a is fitted in the holes 70a, 70a, and the disk 7
It is provided at a position displaced from the center of 2b and 72b in the radial direction. Reference numerals 71 and 71 denote drive motors, and reference numerals 71a and 71a denote drive motors 71 and 7.
The drive shaft of No. 1 is shown. The drive shafts 71a, 71a have a cylindrical shape, and the cylinders 72 of the disks 72b, 72b are
It is fitted to c and 72c. Therefore, the drive motor 71,
When 71 is rotationally driven, this rotational driving force is transmitted to the discs 72b, 72b, and the drive pins 72a,
The original table 70 moves in parallel while drawing a circle on the same plane via 72a. The radius of the circle drawn by this document table 70 is
Pins 72a, 72 from the center of the disks 72b, 72b
It matches the distance to a. In addition, the drive motor 7
Reference numerals 1 and 71 denote motors capable of controlling drive rotation in a positional manner. For example, a stepping motor or the like is used to drive the drive motors 71 and 71 in the same direction and at the same angle (synchronous rotation drive). Let

In FIG. 2, the drive motors 71, 71 are
Is rotated once, that is, the driving bodies 72, 72
The movement distance of the document table 70 when rotated will be described. Reference numeral 73 indicates a guide plate on the entrance side in the transport direction,
Reference numeral 74 indicates a guide plate on the exit side in the transport direction.
The guide plates 73 and 74 are provided to support the document table 70 and smoothly convey the document. Reference numeral 75 indicates the maximum movement distance of the document table 70 in the document transport direction. Here, the document table 70 is shown in FIG.
As shown in (a), it is assumed that the drive motor 7 is displaced toward the entrance side in the document conveying direction, and from this state, the drive motor 7
When 1 and 71 rotate by 180 degrees, this rotational driving force is transmitted to the document table 70 via the driving bodies 72 and 72 and the drive pins 72a and 72a, and the document table 70 is as shown in FIG. 2 (b). And moves toward the exit side in the document transport direction. Further, when the drive motors 71, 71 rotate by 180 degrees, the document table 70 moves to the position shown in FIG. That is, the maximum movement distance 75 of the original table 70 in the original conveying direction = distance from the center of the disks 72b, 72b to the pins 72a, 72a × 2.

Further, the drive motors 71, 71 are intermittently operated by a timer, for example, for a fixed time regardless of whether the original is being conveyed, or when the drive motors 71, 71 are stepping motors. It is possible to move the document table 70 by an arbitrary amount of movement at an arbitrary time by arbitrarily controlling the drive pulse.

After feeding one A1 size original document and rotating the drive motors 71, 71 by 5 degrees,
A copy in which a black line is easily generated when a plurality of A1 size originals are set to be conveyed, and a black line is generated when the platen 70 is moved or fixed As a result of comparing the numbers of sheets, the frequency of occurrence of the black line when the document table 70 is moved is determined as follows.
About 1/10 of the frequency of black lines when 0 is fixed
Could be reduced to

As described above, the document table 70 is driven by the drive motors 71, 71.
An example of the case of automatically moving the document table 70 has been described above. Next, a case of manually moving the document table 70 will be described with an example. In FIG. 3, reference numeral 8
Reference numeral 0 indicates a document table. This document table 80 has a circular hole 8 into which pins of drive levers 81, 81 described later fit.
0a, 80a are provided and the holes 80a,
80a is installed at a position where the original is not involved even if the original is conveyed. Reference numerals 81 and 81 denote drive levers, and cylindrical pins 81a and 81a are provided at one ends of the drive levers 81 and 81, respectively.
On the other hand, the other end of the drive levers 81, 81 has a pin 81
b and 81b are provided. The pins 81b, 81b
Is attached to the main body, and the drive levers 81 and 8 are
1 can be rotated. Therefore, the drive levers 81, 81 have the pins 81b, 81b as fulcrums,
It can rotate in the horizontal plane. Reference numeral 82 indicates a left-right interlocking lever. The left and right interlocking lever 82 is provided with pins 82a and 82a between the pins 81a and 81a and the pins 81b and 81b.
The reference numeral 82a designates the drive levers 81, 81 to the pins 81b, 8
It is connected to the drive levers 81, 81 so as to be rotationally driven with 1b as a fulcrum. Further, one end of the left-right interlocking lever 82 is formed in an L shape as indicated by reference numeral 82b, and the document table 80 is manually operated by the L-shaped portion 82b. The L-shaped portion 82b projects to the outside of the main body and can be easily manually operated from the outside of the main body. The drive levers 81, 81, the interlocking lever 8
2. The document table 80 constitutes a parallel link.

Next, the manual operation of the original table 80 will be described. The L-shaped portion 82b of the left and right interlocking lever 82
Is manually reciprocated in the α direction, the drive lever 8
1, 81 rotate in the β direction with the pins 81b, 81b as fulcrums. The drive levers 81, 81 have pins 81b, 81.
By rotating in the β direction with b as a fulcrum, the drive lever 81,
The document table 80 also rotates in the β direction via the pins 81 b and 81 b of 81. Therefore, when the manuscript is read and a black line 69 shown in FIG. 10B appears in the read image, the L-shaped portion 82b of the left and right interlocking lever 82 is manually operated in the α direction. By rotating the document table 80 in the β direction, the black line 69 as described above is generated.
Can be eliminated. In the above example, the document table 80 is configured to move in a direction substantially orthogonal to the document transport direction, but it may be configured to move in the document transport direction.

An example of the case of manually rotating the document table 80 has been described above. Next, the document table 8 will be described.
An example in which 0 is manually moved only in the document transport direction will be described. In FIG. 4, reference numeral 90 indicates a document table. Further, reference numerals 91 and 92 denote wall surfaces which are a part of the main body. On the wall surface 92, screws 94,
94 (in this case, two sets of screws are used) are fitted, and the tips of the screws 94, 94 are in contact with the side surface 90b of the document table 90. One side 90a of the document table 90
And the wall surface 91, elastic members 93, 93 (in this case, two sets of coil springs are used) are provided so as to press the one side surface 90a of the document table 90 and the wall surface 91. . On the other hand, the other side surface 90b and the wall surface 92 of the document table 90.
Is positioned by the screws 94, 94, so that the document table 90 is positioned between the wall surface 91 and the wall surface 92 by the interaction between the elastic bodies 93, 93 and the screws 94, 94. Here, by rotating the screws 94, 94, the original table 90 can be arbitrarily moved in the original conveying direction (γ direction in FIG. 4). Therefore, when a document is read and a black line 69 shown in FIG. 10B appears in the read image, the screws 94 and 94 are rotated to move the document table 90 in the document conveying direction (see FIG. In (4), it can be arbitrarily moved in the γ direction) to eliminate the above occurrence. The moving direction of the document table 90 may be a direction orthogonal to the document conveying direction.

[0028]

According to the first aspect of the present invention, since the mechanism for moving the document table is provided, dust attached to the document is
It is possible to prevent the adherence and retention on the document table, and it is possible to reduce the occurrence of black lines on the read image due to the adherence and retention of dust.

According to the second aspect of the present invention, the platen is moved in an advancing direction of the document or in a direction perpendicular to the advancing direction, or in a direction in which the advancing direction and the advancing direction are combined. Therefore, when a black line is generated on the read image due to adhesion and retention of dust on the platen, by moving the platen as described above, it is possible to prevent the occurrence as appropriate. be able to.

According to the third aspect of the present invention, since the document table is manually moved, the occurrence of a black line on the read image can be appropriately prevented with a simple mechanism and at low cost. can do.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a document table applicable to a document reading apparatus according to the present invention.

FIG. 2 is an overall side sectional view showing a movement change of the document table.

FIG. 3 is a perspective view showing an example of another document table applicable to the document reading apparatus according to the present invention.

FIG. 4 is a perspective view showing another example of a document table applicable to the document reading apparatus according to the present invention.

FIG. 5 is an overall side sectional view showing an embodiment of a document reading apparatus according to the present invention.

FIG. 6 is a front sectional view showing an example of the optical system in the above embodiment.

FIG. 7 is an overall side sectional view showing another embodiment of a document reading apparatus according to the present invention.

FIG. 8 is a side view showing a portion of the backup roller in the above embodiment.

FIG. 9 is a cross-sectional view showing a conventional example of a document reading device.

FIG. 10 is a front view showing an example of a document used in the conventional example and an image formed by the conventional example.

[Explanation of symbols]

 1 original 2 original table 3 upper unit case 5 original conveying roller pair 6 original conveying roller pair 7 original conveying roller pair 11 original table 14 backup roller 16 reading element 70 original table 71, 71 drive motor 80 original table 90 original table

Claims (3)

[Claims] 1. A pair of document conveying rollers for conveying various documents to a document reading unit, a one-dimensional reading element for converting an image on the document moving in the reading unit into an electric signal, and a document in the reading unit. An illuminating device for illuminating the document, a transparent platen provided in the recording section, and a backup roller which is arranged so as to face the platen and rotates while pressing the document passing through the platen against the platen. A document reading device, comprising a mechanism for moving the document table. 2. The document table is movable at any time and in an arbitrary amount in a traveling direction of a document, a direction perpendicular to the traveling direction, or a combination of the traveling direction and the right-angle direction. The original reading device according to claim 1. 3. The document reading device according to claim 1, wherein the document table is manually movable.