JPH10190938A - Image reader and image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader of high quality capable of effectively using the lens of a shallow field depth, improving productivity and carrying a thick original without problems, while improving image read accuracy by arranging a light-transmitting member between an image read means and a sheet and fixing a distance between the image read means and images on the sheet. SOLUTION: Since the rotation center of a read drive roller 7a is arranged on a carrying direction back side from the rotation center of a read driven roller 13a, the carrying direction of the original S which is the sheet is turned downwards and an original back surface is advanced, while being in contact with the upper surface of a transparent glass 7c which is the light-transmitting member of a back surface read part 7. At this time, the interval of front and back transparent glasses 7c and 13c is fixed, and the original S is pressed to the transparent glass 7c of the back surface read part 7. Thus, for a lens 7e of the back surface, since the possibility of being out of focus is not present, even when the lens of the shallow field depth is used and the light quantity of a light source can be less, accompanying this, the image read of high accuracy is performed without lowering production efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for conveying a sheet-shaped document and reading image information on both sides of the document.

[0002]

2. Description of the Related Art Conventionally, as a flow-reading type image reading apparatus, there are a scanner dedicated to one-sided reading and a scanner for such a double-sided reading, and an image reading section includes an image reading sensor such as a contact sensor. What is provided is general.

[0003] The scanner for single-sided reading only has a structure in which the reading side of the original is brought into close contact with the original platen glass by pressing the back of the original with a roller or the like. The distance is constant, and there is no danger that the lens for forming image information on the contact sensor will be out of focus even with a lens having a small depth of field.

On the other hand, in order to read a two-sided document having images on both sides of the document at a time, a double-sided scanner having image reading sensors such as contact sensors on both front and back sides is required. Also in this double-sided scanner, a lens having a small depth of field can be used if a transport system that sequentially reads images one by one, like the single-side scanner, can be used, but the transport system becomes very long. As a result, the device becomes large.

Therefore, in the conventional scanner for double-sided reading, as shown in FIG. 6, an image reading section 101 for reading an image on the front side of a document S and an image reading section 10 for reading an image on the back side.
2 are arranged and fixed at positions substantially opposite to each other with the sheet therebetween, and are conveyed by a conveying roller so that the sheet is inserted straight between the two image reading units.

[0006]

However, in such a conventional example, the distance between the sensors is fixed, and furthermore, since the sheet is inserted straight between them, some problems arise. I was

That is, if the distance between the sensors is fixed, the distance between the sensors is inevitably increased to accommodate a very thick document. That is, it is necessary to open the space between the front and back glass, which is the document conveyance path, to some extent.

However, if the gap between the front and back glass is opened, when the document having a small thickness is conveyed, the document may be wavy between the front and back glass if the document does not have any rigidity, and the image reading accuracy may be reduced. Leads to a decline.

In addition, if the transport path is such that a sheet is inserted straight between the front and back glass, the distance between the sensor and the document image surface changes with a change in the thickness of the document. That is, in order to read an image corresponding to an original having various thicknesses, a lens having a large depth of field to form an image on a sensor is required in the front and back image reading units.

Further, in such a conveyance path, the above-mentioned original is likely to be wavy, and a lens having a deep depth of field is required for the correction.

However, using a lens with a large depth of field causes the following problems. 1. Since the brightness of the lens becomes dark, the light source must be brightened. Then, a problem of heat generation and power consumption arises. In particular, a radiator plate and a cooling fan are required to suppress heat generation, which causes a large size and a decrease in productivity. In addition, the light source itself must be special, and the productivity deteriorates. 2. Since the size of the lens becomes large, space saving is adversely affected, and the productivity of the lens itself is poor. The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to improve the image reading accuracy and improve the productivity in which a lens with a small depth of field can be effectively used. Another object of the present invention is to provide a high quality image reading apparatus capable of conveying a thick original without any problem.

[0012]

In order to achieve the above object, according to the present invention, there is provided a flow-reading type image reading means for reading an image of a sheet being conveyed at a position substantially opposed to the sheet. And an image reading device for reading images on both sides of a sheet substantially simultaneously, wherein at least one of the two image reading units and an image read by the image reading unit are provided. The distance is always constant when reading any sheet.

That is, either the front surface or the back surface of the sheet is always located at the reference plane regardless of the thickness of the sheet, and the lens on that side needs to have a depth of field. Therefore, a lens with good productivity and a small depth of field can be used.

More specifically, a light transmissive member is arranged between the image reading means and the sheet, and the sheet is brought into close contact with the light transmissive member, so that the distance between the image reading means and the image on the sheet is increased. Is preferably constant.

It is also preferable that the sheet conveying path immediately before the image reading means is formed in a direction in which the sheet comes into close contact with the light transmitting member.

For example, there is a sheet transporting path in which the sheet is brought into contact with the light transmitting member at a predetermined angle and is conveyed along the light transmitting member by utilizing the softness of the sheet.

Further, it is preferable to provide a pressing means for pressing a sheet against the light transmitting member in a sheet conveying path immediately before the image reading means.

In addition, two flow-reading type image reading means for reading an image of a sheet being conveyed are arranged at substantially opposite positions across the sheet so that images on both the front and back sides of the sheet are read almost simultaneously. In the reading apparatus, the distance between the two image reading units is variable.

One of the two image reading means is fixed,
It is preferable to provide a pressing unit that presses the other image reading unit against the fixed image reading unit.

It is also preferable that the image recording apparatus is provided with the above-mentioned image reading apparatus and an image recording means for recording an image read by the image reading apparatus.

[0021]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(Embodiment 1) FIG. 5 is a cross-sectional view of a scanner to which the present invention is applied. In FIG.
Is a lower machine box, 2 is an upper machine box, and the upper machine box 2 is rotatable about a fulcrum 3 with respect to the lower machine box. S is a document as a sheet to be read by the scanner, 4 is a paper feed tray for loading the document S, 5 is 5a depending on the number of loaded documents S.
Is a document table rotatable around the fulcrum. In the lower machine box 1,
A separation roller 6 for preventing the second and subsequent originals S from entering the transport path, a back side reading unit 7 for illuminating image information on the lower surface of the original S and reading it by a contact sensor, and a paper discharge drive for discharging the original S outside the machine A roller 8 is included, and a transport guide 9 for guiding the document S and a transport driving roller 10 for transporting the document S are arranged. The discharge drive roller 8 and the transport drive roller 10 are driven directly by a motor (not shown). On the other hand, inside the upper machine box 2, a paper feed roller 11 for feeding the uppermost document S stacked on the paper feed tray 4, a feed roller 12 for feeding the document into the machine, and image information of the upper surface of the document S are stored. A front side reading unit 13 illuminated and read by a contact sensor, a paper discharge roller 14 for discharging the document S out of the machine are included, and a transport guide 15 for guiding the document S and a transport roller 16 for transporting the document S are arranged. . The transport guides 9 and 15 immediately before the reading unit are curved, and enter the reading unit from obliquely above. The upper surface 17 of the upper machine box 2 is a paper discharge tray, which accommodates the document S discharged out of the apparatus by a pair of paper discharge rollers 8.

Next, the operation of the scanner will be described.
An original S for which image information is to be read is stacked on the paper feed tray 4, and a scan start command is transferred on a personal computer electrically connected to the scanner. Then, the platen 5
Is rotated counterclockwise around a fulcrum 5a by a motor (not shown), and stops when the uppermost sheet of the document S comes into contact with the paper feed roller. In this state, the feed roller 11 rotates in the direction of the arrow, and conveys the uppermost sheet of the document S into the apparatus. Since the feed roller 12 is also rotating in the direction of the arrow at the same time as the feed roller, the uppermost document S is further guided inside the apparatus. Here, separation roller 6
Is rotated in the direction opposite to the document transport direction, the second and subsequent documents S from the top on the paper feed tray are pushed back to prevent double feeding. The document S conveyed in this manner is guided by conveyance guides 9 and 15 and sent by conveyance rollers 10 and 16.
The reader enters the reading unit from obliquely above. In the reading unit, image information on the upper surface of the document S is read by the front surface reading unit 13, and image information on the lower surface is read by the back surface reading unit 7, and the information is transmitted to the personal computer. Thereafter, the document S sent by the transport rollers 10 and 16 is discharged out of the apparatus by a pair of discharge rollers 8 and 14 and stored on a discharge tray 17. Next, referring to FIG. 1, a reading unit which is a characteristic part of the first embodiment of the present invention will be described in detail.

The front side reading section 13 is fixed to the upper machine box 2 and the back side reading section 7 is fixed to the lower machine box 1, respectively. A reading drive roller 7a and a reading driven roller 13a
However, at the exit, the reading drive roller 7b and the reading driven roller 13
b are arranged respectively. Here, the reading drive roller 7
The straight line connecting a with each rotation center of the reading driven roller 13a is non-perpendicular to the conveyance path of the reading unit. 7c ・
13c is a transparent glass as a light transmitting member, 7d · 13
d is a contact sensor as image reading means for reading image information of the document and converting it into an electric signal; 7e and 13e are lenses for forming image information of the document on the contact sensor;
f is a light source for illuminating the original. Reading driven roller 13a
13b is vertically movable with respect to the front surface reading unit 13. Also, each axis is a spring 13
g and 13h are pressed against the reading drive rollers 7a and 7b.
3b moves up and down.

Further, since the rotation center of the reading drive roller 7a is located farther in the conveyance direction than the rotation center of the reading driven roller 13a, the conveyance direction of the document S is directed downward.
The back surface of the document advances while contacting the upper surface of the transparent glass 7c of the back surface reading unit 7. Then, first, the image information on the surface of the document irradiated by the light source 13f is read by the contact sensor 13d.
At this time, since the distance between the front and back transparent glasses 7c and 13c is constant and the original is pressed against the transparent glass 7c of the back side reading unit 7, the distance between the original front surface and the transparent glass 13c changes only by the thickness of the original. The position does not change due to the ripple of the original. Next, image information on the back surface of the document irradiated by the light source 7f is read by the contact sensor 7d. At this time, since the back surface of the document is pressed against the transparent glass 7c, the position of the back surface of the document and the position of the contact sensor are always the same. Therefore, the lens 7e on the back side does not lose focus even if a lens having a small depth of field is used, and accordingly, the light amount of the light source can be reduced, thereby increasing the size of the apparatus and reducing the production efficiency. High-precision image reading can be performed without the need for the image reading.

(Embodiment 2) FIG. 2 is a diagram showing a reading unit according to a second embodiment.

In the first embodiment, the transport path immediately before the reading section is curved in order to bring the original into contact with the transparent glass of the reading section. However, in the second embodiment, the transport path is not curved. . Instead, immediately before the transparent glass, an original pressing spring 50 which is a pressing means for pressing the original against the back glass.
Is provided. By providing the document pressing spring 50, the same effect as in the first embodiment can be obtained. Further, since the transport path immediately before reading can be made linear, the component shape is simplified, and the transport performance of the document is improved.

Further, if a function for pressing a document is provided,
A thin sheet or the like may be used instead of the document pressing spring 50.

The other configuration is the same as that of the first embodiment, and the description is omitted. Also, in the reading unit illustrated in FIG. 2, the numbers and descriptions of the parts common to the first embodiment are omitted.

(Embodiment 3) FIG. 3 is a diagram showing a reading unit according to a third embodiment. Back side reading unit 60 is lower machine box 1
It is fixed to. A reading drive roller 60 is provided at the entrance of the reading unit.
a and a read driven roller 70a, and a reading drive roller 60b and a read driven roller 70b are disposed at the exit. 60c / 70c is a transparent glass, 60d / 70d is a contact sensor that reads image information of the document and converts it into an electric signal, 60e / 70e is a lens that forms image information of the document on the contact sensor, and 60f / 70f is a It is a light source to illuminate. The front surface reading unit 70 is vertically movable with respect to the upper machine box 2 and is a spring 70g / 70 serving as an urging means.
h, the reading driven roller 70 is urged downward.
a and 70b are pressed against the reading drive rollers 60a and 60b. Therefore, the reading driven roller 70a is set in accordance with the thickness of the original.
Since 70b moves up and down, the reading unit moves up and down as a result.

In the first and second embodiments, the focus position on the side that is not pressed against the glass (upper side in the figure) is slightly deviated due to the thickness of the original, and the gap between the front and back glass is fixed, so that the thicker original is used. Could not be transported. But,
In the third embodiment, since the front side reading unit 70 moves in accordance with the thickness of the original, the original can be conveyed regardless of the thickness. Since there is no need to keep the gap between the glasses, the focus position does not change so much even if the document undulates between the front and back glasses. (Fourth Embodiment) FIG. 4 is a diagram showing a reading unit according to a fourth embodiment. The back surface reading unit 80 is fixed to the lower machine box 1. A reading driving roller 80a and a reading driven roller 90a are arranged at the entrance of the reading unit, and a reading driving roller 80b and a reading driven roller 90b are arranged at the exit. 80
c / 90c is a transparent glass; 80d / 90d is a contact sensor for reading image information of a document and converting it into an electric signal;
Reference numerals e and 80e denote lenses for forming image information of the document on the contact sensor, and reference numerals 80f and 90f denote light sources for illuminating the document.
The front surface reading unit 90 is vertically movable with respect to the upper machine box 2 and is urged downward by springs 90g and 90h, so that the reading driven rollers 90a and 90b are pressed against the reading driving rollers 80a and 80b. . Accordingly, the reading driven rollers 90a and 90b move up and down according to the thickness of the document, and as a result, the reading unit moves up and down.

Further, since the rotation center of the reading drive roller 80a is located farther in the conveyance direction than the rotation center of the reading driven roller 90a, the conveyance direction of the document S is directed downward, and the back surface of the document S Of the transparent glass 80c. Then, first, the image information on the surface of the document irradiated by the light source 90f is read by the contact sensor 90d. At this time, the front-side reading unit moves upward by the amount by which the reading driven roller 90a is lifted by the thickness of the document, so that the distance between the front surface of the document and the surface contact sensor 90d is always constant regardless of the thickness of the document. . Next, the light source 8
The image information on the back side of the document irradiated with 0f
Read at d. At this time, the back of the original is transparent glass 80
c, so that the back of the document and the contact sensor 8
The distance from 0d is always the same.

Accordingly, the front lens 90e and the rear lens 80e do not become out of focus even when a lens having a small depth of field is used, and the light amount of the light source can be reduced accordingly. It is possible to improve the reading accuracy of a double-sided image without causing a reduction in production efficiency and production efficiency.

Further, the front-side reading unit 90 according to the thickness of the document
Moves, so that the original can be conveyed regardless of the thickness.

(Other Embodiments) In the above-described embodiment, a scanner for reading an image of a conveyed document has been exemplified as an image reading apparatus to which the present invention is applied. However, the present invention is not limited to this. For example, in an image recording apparatus such as a copying machine or a facsimile apparatus, even if the present invention is applied to a document image reading unit, the same effect as the above effect can be obtained.

[0036]

As described above, according to the present invention,
The following effects are obtained. 1. Since the optical performance such as the depth of field of the lens that forms the image information of the document on the contact sensor can be reduced,
The productivity of the lens itself is good, and a device with good productivity can be provided. 2. Since a lens with a small depth of field can be used, the light amount of the light source for illuminating the document can be reduced, and a light source with good productivity can be selected. In addition, since power consumption is reduced and heat generated is small, a heat-radiating plate, a cooling fan, and the like are not required, and a device with high productivity can be provided. 3. The image can be read with high resolution with little or no focus shift. 4. Thick originals can be conveyed, and jams are less likely to occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a reading unit of a scanner according to a first embodiment of the invention.

FIG. 2 is a cross-sectional view illustrating a reading unit of a scanner according to a second embodiment of the invention.

FIG. 3 is a cross-sectional view illustrating a reading unit of a scanner according to a third embodiment of the invention.

FIG. 4 is a cross-sectional view illustrating a reading unit of a scanner according to a fourth embodiment of the invention.

FIG. 5 is a cross-sectional view illustrating a scanner according to the invention.

FIG. 6 is a cross-sectional view illustrating a reading unit of a scanner according to a conventional example.

[Explanation of symbols]

7, 60, 80 Back reading unit 13, 70, 90 Front reading unit 7f, 13f, 60f, 70f, 80f, 90f Lens S Sheet-shaped original

Claims (7)

[Claims] An image reading means for reading an image of a sheet being conveyed is provided at two positions substantially opposite to each other across a sheet, and images on both sides of the sheet are read almost simultaneously. In the reading device, a distance between at least one of the two image reading units and an image read by the image reading unit is always constant when reading any sheet. Image reading device. 2. A light transmissive member is arranged between the image reading means and the sheet, and the sheet is brought into close contact with the light transmissive member, so that the distance between the image reading means and the image on the sheet is reduced. 2. The image reading apparatus according to claim 1, wherein the image reading apparatus is fixed. 3. The image reading apparatus according to claim 2, wherein a sheet conveyance path immediately before said image reading means is formed in a direction in which a sheet comes into close contact with said light transmitting member. 4. An image reading apparatus according to claim 2, wherein a pressing means for pressing a sheet against said light transmitting member is provided in a sheet conveying path immediately before said image reading means. . 5. An image reading means for reading an image of a sheet being conveyed is provided at two positions substantially opposed to each other with the sheet interposed therebetween, and the images on both sides of the sheet are read almost simultaneously. An image reading apparatus, wherein a distance between the two image reading units is variable. 6. An image forming apparatus according to claim 5, wherein one of said two image reading means is fixed, and urging means for urging the other image reading means against the fixed image reading means is provided. The image reading device according to claim 1. 7. An image recording apparatus comprising: the image reading apparatus according to claim 1; and an image recording means for recording an image read by the image reading apparatus.