JP3524311B2 - Image reading device and image recording device - Google Patents

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 which conveys a sheet-like document and reads image information on both front and back surfaces of the document.

[0002]

2. Description of the Related Art Conventionally, there are a single-sided scanning dedicated scanner and a double-sided scanning scanner as a flow-reading type image reading apparatus, and an image reading sensor such as a contact sensor is provided in the image reading section. Those provided are general.

Since the scanner for exclusive use in single-sided reading has a structure in which the reading side of the document is brought into close contact with the platen glass by pressing the back side of the document with a roller or the like, the read image of the document and the image reading sensor are combined. The distance is constant, and the lens for forming the image information on the contact sensor has no risk of being out of focus even with a lens having a shallow depth of field.

On the other hand, in order to read a double-sided original having an image on both sides of the original at one time, a double-sided scanner having image reading sensors such as contact sensors on the front and back sides is required. Even in this double-sided scanner, a lens with a shallow depth of field can be used if a transport system is used that sequentially reads images one by one like the above-described one-sided dedicated scanner, but that would make the transport system very long. Therefore, the device becomes large.

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

[0006]

However, in such a conventional example, since the distance between the sensors is fixed and the sheet is inserted straight in the middle, some problems occur. Was there.

In other words, if the distance between the sensors is fixed, the distance between the sensors is inevitably increased in order to accommodate an extremely thick document. That is, it is necessary to open the space between the front and back glass, which is the document transport path, to some extent.

[0008] However, if the front and back glasses are open as described above, when the original having a small thickness is conveyed, the original will be waved between the front and back glasses if the original is not stiff, and the image reading accuracy will be deteriorated. Lead to a decline.

Further, if the sheet is conveyed straight in the middle of the front and back glass, the distance between the sensor and the image surface of the original will change as the thickness of the original changes. That is, in order to perform image reading corresponding to documents of various thicknesses, lenses having a deep depth of field that are focused on the sensor are required in the front and back image reading units.

Further, in such a conveying path, the above-mentioned waviness of the document is apt to occur, and a lens having a deep depth of field is also required for the correction.

However, the use of a lens having a deep depth of field causes the following problems. 1. Since the brightness of the lens will be dark, you have to make the light source bright. Then, problems of heat generation and power consumption occur, and in particular, a heat radiating plate and a cooling fan are required to suppress heat generation, which causes a size increase and deterioration of productivity. In addition, the light source itself must be a special one, resulting in poor productivity. 2. Since the size of the lens becomes large, it becomes a harmful effect of space saving, and the productivity of the lens itself is poor. The present invention has been made 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 to effectively use a lens having a shallow depth of field, which has high productivity. Another object of the present invention is to provide a high-quality image reading apparatus that can convey a thick original without any problem.

[0012]

In order to achieve the above object, in the present invention, two flow reading type reading units for reading an image of a sheet being conveyed are provided at positions substantially opposite to each other with the sheet sandwiched therebetween. In the image reading device, the two reading units are arranged to read images on both front and back sides of the sheet at substantially the same time.
One of the reading units is fixed to the image reading device.
Image reading that reads the image information on the sheet
Means and the sheet by bringing the sheet into close contact
Set to keep the distance between the step and the image on the sheet constant.
Light-transmitting member and the sheet of the image reading means.
No. provided on the upstream side and the downstream side
And one of the two reading units.
One reading unit reads the image information of the sheet.
The image is read by bringing the sheet and the sheet into close contact with each other.
To keep the distance between the means and the image on the sheet constant
The provided light transmissive member and the first transport roller are paired.
The second pair of transport rollers facing each other move together
In order to prepare for the above, the one reading unit is different from the other reading unit.
The seat is provided with the biasing means for biasing
Adhere to the light-transmissive member provided in the other reading unit
Together with the one image reading unit and the other image reading unit
It is characterized in that the distance to and is variable .

That is, either the front surface or the back surface of the sheet is always positioned on the reference surface regardless of the thickness of the sheet, and therefore the lens on that side needs a depth of field depth. Therefore, a lens with good productivity and a shallow depth of field can be used.

[0014]

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

For example, there is a sheet conveying path that abuts the light transmitting member at a predetermined angle and uses the softness of the sheet to convey the sheet along the light transmitting member.

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

[0018]

[0019]

It is also preferable that the image recording apparatus includes the image reading apparatus as described above and has an image recording unit for recording an image read by the image reading apparatus.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, shape, relative arrangement, etc., are not intended to limit the scope of the present invention thereto.

(Embodiment 1) FIG. 5 is a cross-sectional view of a scanner to which the present invention is applied. 1 in the figure
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 on which the document S is stacked, and 5 is 5a depending on the number of stacked documents S.
This is a manuscript table that can be rotated around a fulcrum. In the lower machine box 1,
Separation roller 6 that prevents the second and subsequent documents S from entering the conveyance path, back side reading unit 7 that illuminates the image information on the lower surface of document S and reads it with a contact sensor, and sheet ejection drive that ejects document 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 paper discharge drive roller 8 and the transport drive roller 10 are directly connected to a motor (not shown) to be driven. On the other hand, in the upper machine box 2, a paper feed roller 11 for feeding the uppermost original S stacked on the paper feed tray 4, a feed roller 12 for feeding the original into the machine, and image information of the upper surface of the original S are displayed. A front surface reading unit 13 that illuminates and reads with a contact sensor, a discharge roller 14 that discharges the document S to the outside of the machine, and a conveyance guide 15 that guides the document S and a conveyance roller 16 that conveys the document S are arranged. . The transport guides 9 and 15 immediately in front of the reading unit are curved and enter the reading unit obliquely from above. Further, the upper surface 17 of the upper machine box 2 is a paper discharge tray, and accommodates the document S discharged outside the machine by a pair of paper discharge rollers 8 and 14.

Next, the operation of this scanner will be described.
A document S whose 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 manuscript table 5
Rotates counterclockwise by a motor (not shown) about the fulcrum 5a, and stops when the uppermost sheet of the document S comes into contact with the sheet feeding roller. In this state, the paper feed roller 11 rotates in the direction of the arrow to convey the uppermost paper of the document S into the machine. Since the feed roller 12 also rotates in the direction of the arrow at the same time as the paper feed roller, the uppermost document S is guided further into the interior of the machine. Separation roller 6 here
Rotates in the direction opposite to the document transport direction, the second and subsequent documents S on the paper feed tray are pushed back to prevent double feeding. The document S thus transported is guided by the transport guides 9 and 15 and is transported by the transport rollers 10 and 16.
Enter the reading unit from diagonally above. In the reading unit, the image information on the upper surface of the document S is read by the front surface reading unit 13 and the image information on the lower surface is read by the back surface reading unit 7, and the information is transmitted to the personal computer. After that, the document S sent by the transport rollers 10 and 16 is discharged outside the apparatus by the pair of discharge rollers 8 and 14, and is stored on the discharge tray 17. Next, with reference to FIG. 1, a reading unit which is a characteristic part of the first exemplary embodiment of the present invention will be described in detail.

The front surface reading section 13 is fixed to the upper machine box 2, and the back surface reading section 7 is fixed to the lower machine box 1. A reading driving roller 7a and a reading driven roller 13a are provided at the entrance of the reading unit.
However, the reading drive roller 7b and the reading driven roller 13 are provided at the exit.
b are arranged respectively. Here, the reading drive roller 7
A straight line connecting the rotation centers of a and the reading driven roller 13a is not 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 an image reading means for reading the 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, and 7f and 13
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. In addition, each axis has a spring 13
Since the pressure is applied to the reading driving rollers 7a and 7b at g · 13h, the reading driven roller 13a · 1 is set in accordance with the thickness of the document.
3b moves up and down.

Further, since the rotation center of the reading drive roller 7a is arranged on the back side of the rotation center of the reading driven roller 13a in the conveyance direction, the conveyance direction of the document S is directed downward.
The document moves forward while the back surface of the original comes into contact with 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 illuminated 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 front surface of the original and the transparent glass 13c changes only by the thickness of the original. However, the position of the original does not change due to waviness. Next, the image information on the back surface of the document illuminated by the light source 7f is read by the contact sensor 7d. At this time, since the back surface of the original is pressed against the transparent glass 7c, the back surface of the original and the contact sensor are always at the same position. Therefore, even if a lens with a shallow depth of field is used as the lens 7e on the back surface, there is no risk of out of focus, and the light amount of the light source can be reduced accordingly, which leads to an increase in the size of the device and a reduction in production efficiency. It is possible to read an image with high accuracy without doing so.

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

In the first embodiment, the conveying path immediately before the reading section is curved in order to bring the original into contact with the transparent glass of the reading section, but in the second embodiment, the conveying path is not curved. . Instead, just 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 that of the first embodiment can be obtained. Further, since the conveyance path immediately before reading can be made straight, the shape of the parts is simplified and the conveyance performance of the document is also improved.

Further, if it has a function of pressing an original,
A thin sheet or the like may be used instead of the document pressing spring 50.

Since the other structure is common to the first embodiment, the description is omitted. Also in the reading unit shown in FIG. 2, the numbers and explanations of the portions common to the first embodiment are omitted.

(Third Embodiment) FIG. 3 is a diagram showing a reading unit according to a third embodiment. The back side reading unit 60 is the 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 reading driven roller 70a, and a reading drive roller 60b and a reading driven roller 70b are arranged at the outlet. 60c and 70c are transparent glass, 60d and 70d are contact sensors that read image information of a document and convert them into electric signals, 60e and 70e are lenses that image the image information of the document on the contact sensor, and 60f and 70f are documents. It is a light source to illuminate. The front surface reading unit 70 is movable in the vertical direction with respect to the upper machine case 2, and has springs 70g and 70 as biasing means.
Since it is urged downward by h, the reading driven roller 70
The a and 70b are brought into pressure contact with the reading drive rollers 60a and 60b. Therefore, depending on the thickness of the original, the reading driven roller 70a
-Since 70b moves up and down, the reading unit consequently moves up and down.

In the first and second embodiments, the focus position on the side not pressed against the glass (upper side in the figure) is slightly deviated due to the thickness of the original, and the distance between the front and back glasses is fixed, so that the original is thicker than that. Could not be transported. But,
In the third embodiment, since the front side reading unit 70 moves according to the thickness of the original, the original can be conveyed regardless of the thickness, and when the reading driving roller and the reading driven roller are in pressure contact with each other, Since it is not necessary to take a lot of space between the glasses, even if the original is wavy between the front and back glasses, the focus position does not change so much. (Fourth Embodiment) FIG. 4 is a diagram showing a reading unit according to the fourth embodiment. The back surface reading unit 80 is fixed to the lower machine case 1. A reading drive roller 80a and a reading driven roller 90a are arranged at the entrance of the reading unit, and a reading drive roller 80b and a reading driven roller 90b are arranged at the exit. 80
c / 90c is transparent glass, 80d / 90d is a contact sensor for reading image information of a document and converting it into an electric signal, 80
Reference numerals e.80e are lenses for forming image information of the original on the contact sensor, and reference numerals 80f and 90f are light sources for illuminating the original.
The surface reading unit 90 is movable in the vertical direction with respect to the upper machine case 2 and is urged downward by the springs 90g and 90h, so that the reading driven rollers 90a and 90b are pressed against the reading drive rollers 80a and 80b. . Therefore, 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 center of rotation of the reading drive roller 80a is located on the rear side of the center of rotation of the reading driven roller 90a in the conveyance direction, the conveyance direction of the document S is directed downward, and the back side of the document is the back side reading section 80. It advances while contacting the upper surface of the transparent glass 80c. Then, first, the image information on the surface of the document illuminated by the light source 90f is read by the contact sensor 90d. At this time, the front surface 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 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 illuminated with 0f is the contact sensor 80.
Read at d. At this time, the back of the original is transparent glass 80
Since it is pressed against c, the back surface of the original and the contact sensor 8
The distance from 0d is always the same.

Therefore, the front surface lens 90e and the rear surface lens 80e do not have a possibility of being out of focus even if a lens having a shallow depth of field is used, and the light quantity of the light source can be reduced accordingly, so that the apparatus is large-sized. It is possible to improve the reading accuracy of double-sided images without causing a decrease in productivity and production efficiency.

In addition, the front side reading section 90 is provided according to the thickness of the original.
Since the document moves, the document can be conveyed regardless of its thickness.

(Other Embodiments) In the above-mentioned embodiments, a scanner for reading an image of a conveyed original document is illustrated as an image reading apparatus to which the present invention is applied, but the present invention is not limited to this. For example, in an image recording device such as a copying machine or a facsimile device, even if the present invention is applied to the original image reading portion, the same effects as the above effects can be obtained.

[0036]

As described above, according to the present invention,
It has the following effects. 1. Since the optical performance such as the depth of field of the lens that forms the image information of the original on the contact sensor can be lowered,
The productivity of the lens itself is good, and thus a device with good productivity can be provided. 2. Since a lens with a shallow depth of field can be used, a light source for illuminating a document needs a small amount of light, and a light source with good productivity can be selected. Further, since the power consumption is reduced and the generated heat is also small, it is possible to provide a device with good productivity without the need for a radiator plate, a cooling fan or the like. 3. It is possible to read with high resolution with little or no focus shift. 4. Even thick originals can be transported and jams are unlikely to occur.

[Brief description of drawings]

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

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

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

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

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

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

[Explanation of symbols]

7, 60, 80 Back side reading unit 13, 70, 90 Front side reading unit 7f, 13f, 60f, 70f, 80f, 90f Lens S Sheet-like document

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-5-160953 (JP, A) JP-A-1-171360 (JP, A) JP-A-2-148962 (JP, A) JP-A-64- 17558 (JP, A) JP-A-1-190167 (JP, A) Actual opening 2-137164 (JP, U) Actual opening 1-81062 (JP, U) Actual opening 1-122668 (JP, U) Practical report 1-135864 (JP, U) Practical report Sho 58-8264 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 1/00-1/207

Claims (2)

(57) [Claims] 1. An image reading apparatus for arranging two flow-reading type reading sections for reading an image of a sheet being conveyed, at substantially opposite positions with the sheet sandwiched therebetween, for reading images on both front and back sides of the sheet substantially at the same time. In the apparatus, one of the two reading units is the image reading unit.
The image information of the sheet is fixed on the device and
Adhering the image reading means to be read to the sheet
To reduce the distance between the image reading means and the image on the sheet.
The light-transmissive member provided for the purpose of
It is arranged on the upstream side and the downstream side of the sheet feeding direction of the picking means.
A first transport roller provided for each of the two reading units, and the other reading unit of the two reading units is configured to
Adhesion between the sheet and the image reading unit that reads image information
By doing so, the image reading means and the image on the sheet are
A light-transmissive member provided in order to keep the distance constant,
A second transport roller that faces the first transport roller and forms a pair.
And a roller, and the other reader is biased against the one reader.
By providing a biasing means, the sheet is read on the one side of the reading unit.
The light-transmissive member provided on the
Note the distance between one image reading unit and the other image reading unit
An image reading device characterized by being variable. 2. An image recording apparatus comprising the image reading apparatus according to claim 1 and comprising an image recording means for recording an image read by the image reading apparatus.