JPH01233875A - Picture reader - Google Patents

Abstract

PURPOSE:To accurately read original picture information without duplication or missing by moving a solid-state image pickup element in the direction of the optical axis of an image forming lens in response to the displacement from the original read position. CONSTITUTION:A displacement detection means 16 consists of a semiconductor laser 17, a lighting lens 18, an image forming lens 19, and a photodetector 20. Moreover, a solid-state image pickup element moving means displaces the solid-state image pickup elements 6, 7 in the optical axis direction of image forming lenses 4, 5 in response to the displacement DELTAx of the original 1 detected by the displacement detection means 16. Based on the electric signal detected by the displacement detection means 16, the solid-state image pickup elements 6, 7 are moved in the optical axis direction of the image forming lenses 4, 5 respectively by the solid-state image pickup element moving means to revise the read effective picture element area. Thus, duplication or missing in a connection part C of the original 1 is eliminated to read an accurate picture.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image reading device that reads image information of a document using a solid-state image sensor.

BACKGROUND OF THE INVENTION A conventional image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 54-6713 will be described. That is,
As shown in FIG. 13, while the original 1 is fed by the conveyance roller 2 and supported by the back positioning plate 3, the image information of the left half A and the right half B of the original 1 is transferred in the main scanning direction S.
The image information of the document 1 is read by the solid-state image sensors 6 and 7, which are divided and reduced by the imaging lenses 4 and 5 provided in the original document 1, respectively. In this case, the left and right reading areas 8 and 9 on the original 1 do not move up and down, and
Further, the relative positions and postures of the solid-state image sensing devices 6 and 7 are strictly adjusted in advance so that they are continuous in a straight line without overlapping or separating at the connecting portion C. .

However, in such a conventional image reading device, no matter how precise the adjustment may be in advance, if the document 1 lifts or moves during operation, duplicate images will be read at the connecting portion C. Therefore,
There is a problem that this leads to significant image deterioration and it is not possible to accurately read the image information of the document 1.

Next, such problems will be explained using specific examples. FIG. 14 shows that the original 1 is moved from the normal reading position P on the top surface of the contact glass 10 by ΔX (usually 0.2 to 0.5 am).
This shows the situation when the position is shifted by .

During normal normal reading, 1M document 1 is at the reading position [
P, read the left half A of the image information between oo and ao with the solid-state image sensor 6, and read the left half A of the image information between oo and ao. Crow.

In between, the right half B of the image information is read by the solid-state image sensor 7. However, it is assumed that document 1 has moved due to lifting or the like and is now at position Q, which is separated by ΔX from the normal reading position P. At this time, 0. The area from 0 to 54 is read by the solid-state image sensor 6, while the area from 0□ to 54 is read by the solid-state image sensor 7. As a result, the overlapped image area from 01 to 0□ is On the solid-state image sensor 6, the portion Δyo will be read.

Next, the amount of movement ΔX of the original 1 and the solid-state image sensor 6 described above are calculated.
The relationship between Δy6 and Δy6, which are read in duplicate above, will be explained using specific numerical values as an example.

now.

Document movement amount: ΔX = 0.5 mm Imaging magnification: l/m = 1/10 Image half angle of view: θ = 20° Assuming that the area of Δy0 that is read overlappingly on the solid-state image sensor 6 is Δ 'Jo=ΔX・(2tanθ/m)...
(1)=0.5・(2tan20°/10):Q,Q364mm=36μm...(2).

Therefore, from equation (2), the overlapped image area from ○ to 02 of original 1 is 36μ on solid-state image sensor 6.
The data will be read over an area of m.

Next, as a solution to the above-mentioned problems of the prior art, for example, there is a method disclosed in Japanese Patent Application Laid-Open No. 59-52965. That is, as shown in FIG. 15, a translucent fill is used as a means for reading image information of the original 1, and solid-state imaging probes 6 and 7 are attached to the translucent fill in directions orthogonal to each other.
will be established. As a result, the light beam incident from the area below the center position C of the original 1 passes through the semi-transparent mirror 11 as it is, travels straight, and forms an image on the solid-state image sensor 6 via the imaging lens 4. A light beam incident from an area above the center position C of the original 1 is reflected by the semi-transparent mirror 11 and is imaged on the solid-state image sensor 7 via the lens 5 .

In this way, by reading the image information of the original 1 in two parts using a semi-transparent fill, even if the original 1 deviates from the normal reading position by ΔX, the transmitted light flux of the original 1 always crosses the center position C. The light beam is divided into two beams, and images are formed on solid-state image sensors 6 and 7, respectively. As a result, manuscript 1
One scanning line is correctly read in half sections from the center position C without any interruption or overlap in the center.

However, in such an image reading method, a translucent fill must be used as a beam splitting means, and the amount of light is limited by the illuminance of the document surface of the illumination system and the sensitivity of the solid-state imaging probe 6°7. The problem is that it cannot be read. Also.

Since it is divided only from the center position C, the imaging lens 4
, 5 (wide angle of view, high resolution, etc.), which limits high-density pixel reading. Furthermore, there is a problem that the document 1 can only be divided into two parts at the center position C, and cannot be applied to wider and higher density reading systems.

Next, a conventional example different from the conventional examples will be described. That is, some conventional image reading apparatuses employ a method of performing shading correction prior to scanning a document in order to correct uneven illumination on the surface of the document. As a device of this kind, Utility Model Application No. 60-145764
This is disclosed in Japanese Patent No. 16, and will be explained based on No. 16@.

A uniform density plate (shading correction plate) 13 for shading correction pressed by a presser plate 12 is attached to the upper part of the contact glass 10 on which the original 1 is set. Thereby, prior to reading the original 1, shading correction is performed by irradiating light from the light source 14 onto the uniform density plate 13 and reading and processing the reflected light or transmitted light by the reading optical system 15.

In this way, in a document fixed type image reading device, the uniform density plate 13 for shading correction is provided on the contact glass 10 adjacent to the document 1, but in a document conveying type image reading device (not shown), A document back position control board installed at the back of the JM document reading position is used as a uniform density board. However, the method using the document rear position control plate in the document transport type often comes into contact with the document 1, resulting in reduced or uneven reflectance due to dirt, damage, etc., and as a result, it cannot function as a uniform density plate for shading correction. There is a problem with deterioration.

the purpose The present invention was made in view of these points.

To provide an image reading device capable of accurately reading image information of a document without duplication or omission, and accurately performing shading correction.

Configuration The first invention includes a displacement amount detection means for detecting the amount of displacement of the original from the reading position, and a solid-state image sensor is moved along the optical axis of the imaging lens according to the amount of displacement of the original detected by the displacement amount detection means. Since the solid-state image sensor moving means for moving the solid-state image sensor in the optical axis direction is provided, the effective reading pixels of the solid-state image sensor are moved by moving the solid-state image sensor in the optical axis direction according to the amount of displacement of the document detected by the displacement amount detection moving means. The area can be changed, and thereby, duplication or omission of image information during reading can be eliminated and accurate reading can be performed.

A second aspect of the invention is to provide a document detecting means for detecting one end of the document, and to position a document pressing member that presses the back surface of the document based on a signal detected by the document detecting device at a reading connecting portion of the document. Since the document pressing member is movably mounted, by pressing the back surface of the document with the document pressing body, it is possible to eliminate overlapping or missing documents at the connecting portion, thereby making it possible to perform accurate reading.

A third invention provides a document detection means for detecting one end of the IjK document, and a document pressing body that presses the back surface of the document based on a signal detected by the document detection means is attached to the reading connection portion of the document. Since a concave part for shading correction is formed in a part of the outer peripheral side of this document presser, by pressing the back side of the document with the document presser, it is possible to prevent overlaps and omissions at the connecting part of the document. This makes it possible to perform accurate reading. Also, by using the recess formed in the document pressing body as a shading correction plate, this shading correction plate does not come into contact with the document, making it possible to perform shading correction. No more staining or damage to the board.
This makes it possible to extend the life of the shading correction plate.
It is possible to perform stable shading correction at all times.

First, an embodiment of the first invention will be described based on FIGS. 1 to 5. Note that the same reference numerals are used for the same parts as in the prior art.

The displacement detection means 16 includes a semiconductor laser 17, an illumination lens 18, an imaging lens 19, and a photodetection element 20. In addition, the solid-state image sensor moving means (not shown) is
Depending on the amount of displacement Δ'X of the original 1 detected by the displacement amount detection means 16, the solid-state imaging probes 6 and 7 are moved by the imaging lens 4.
, 5 in the optical axis direction.

In such a configuration, first, a method for determining the displacement amount ΔX of the document using the displacement amount detection means 16 will be described.

As described in the prior art, the document 1 is at the normal reading position P.
It is assumed that the position is at a position Q displaced by ΔX from . At this time, the following processing is performed by the displacement amount detection means 16.

The light beam emitted from the semiconductor laser 17 is narrowed through the illumination lens 18 and irradiated onto the surface of the document 1.

A portion of the reflected and scattered light depending on the surface condition of the original 1 is projected onto the light receiving surface of the photodetecting element 20 through the imaging lenses 4 and 5 to form an image of the reflected spot. When the original 1 moves in the front-back direction, the imaging lenses 4 and 5 move accordingly.
The image of the reflected spot created by the above also moves on the photodetector element 20.

At this time, the photodetector element 20 detects as an electrical output which position is irradiated with the reflection point and transmits it to an arithmetic circuit (not shown). As a result, the displacement amount Δ of the original 1
X can be extracted as an electrical signal.

In this way, the solid-state image sensors 6 and 7 are moved in the optical axis direction of the imaging lens 4.5 by the solid-state image sensor moving means based on the electric signal detected by the displacement amount detection means 16. The effective reading pixel area can be changed, thereby eliminating overlaps and omissions at the connecting portion C of the original 1, and making it possible to read an accurate image. In addition, for the displacement amount ΔX of the original 1, the solid-state image sensor 6.7
If the amount of movement is Δx1, then 2 Δx1=m2eΔX... (1) However,
m: Imaging magnification.

Next, a modification of this first invention will be explained based on FIG. 5. This is an example in which three imaging lenses and three solid-state imaging devices are used.

As a result, document 1 is divided into three parts and read,
It becomes possible to support higher density and higher number of pixels. Also, in this case, in order to eliminate overlaps and omissions at the connecting portion C of the original 1, the amount of displacement ΔX from the reference reading position [P] of the original 1 is determined.
is read by the displacement amount detection means 16, and the solid-state image sensing elements 6, 7, and 22 are individually moved by the solid-state image sensing element moving means (not shown) according to the amount of displacement, and the effective reading pixel area is changed and processed.

In FIG. 4, if the light from the light source 14 that illuminates the original 1 enters the displacement detection means 16 and causes noise, a filter 23 that transmits only infrared rays used by the displacement detection means 16 is used. is provided between the imaging lens 19 and the photodetecting element 20.

Next, an embodiment of the second invention will be described based on FIGS. 6 to 8. Note that the same reference numerals are used for the same parts as in the first invention.

A document detection sensor 24 serving as document detection means is provided close to the transport roller 2 on the side into which the document 1 is inserted. Further, a document pressing roller 25 serving as a document pressing member is movably attached to the back surface of the document 1 at a connecting portion C where one image is divided and read by the solid-state image sensors 6 and 7.

In such a configuration, when the document 1 is now fed into the interior by the transport roller 2, the document detection sensor 24 detects the leading edge of the document 1. Then, with the original 1 set at the reading position, the original suppressing roller 25 is moved by a control means (not shown) to push the original 1 onto the contact glass 1.
Push it to 0. As a result, the connecting portion C of the original 1 is pressed by the original pressing roller 25 and the contact glass 10 is pressed.
Since it is in contact with the connection part C, there is no duplication or omission at the connection part C, and normal reading can be performed. Thereafter, the end of the transported document 1 is detected by the document detection sensor 2.
4, the document pressing roller 25 leaves the document 1 and returns to its original standby position.

Next, a modification of this embodiment will be explained based on FIG. 8.

This example shows an example using three imaging lenses and three solid-state imaging devices. In this case as well, by movably attaching the document suppressing roller 25 at a position corresponding to the reading connection part C of the yX document 1, normal reading can be performed by eliminating overlapping or missing parts at the connection part C.

Above, we have described how to prevent the document 1 from lifting up at the reading connection section C of the document 1.
When reading a document l whose width is narrower than the document information reading range width, if there is no reflected light in the area where the document 1 is not present, it will be read as a black area, that is, an image area, and will be solid black when displayed as a record.
In digital copiers and the like that use an electrostatic copying process, toner adheres to the drum, resulting in toner consumption and overload during cleaning and fixing. Therefore, in the present invention, by providing the surface of the document suppression roller 25 with the function of a diffusion plate as a diffusion surface with a high reflectance, it is possible to eliminate the phenomenon of solid black that occurs in areas where the document 1 is not present.

Next, an embodiment of the third invention will be described based on FIGS. 9 to 12. This embodiment is a modification of the second invention described above. That is, the document pressing roller 25 is located and movably attached to the back side of the reading connection section C of the document 1, and the document detection sensor 24 is attached to the document pressing roller 25.
is located close to.

The recess 26 according to the present invention is formed in a part of the outer circumferential side surface of the document suppressing roller 25.

This recess 26 is a uniform density plate (
It is used as a shading correction plate) 26. below,
Modifications of the document pressing roller 25 on which the uniform density plate 26 is formed will be sequentially explained based on the drawings.

First, in FIG. 11(a), the document suppressing roller 25 consists of a pipe 28 having a foam material 27 on the outer periphery.
A uniform density plate 26 is formed on a part of the surface. As a result, even if the document suppressing roller 25 comes into contact with the contact glass 1O, the surface will not be damaged, so the straightness, eccentricity, etc. of the document suppressing roller 25 will not be strict, and it will be less likely to bend due to its own weight, allowing for a small diameter. can do.

Next, the document pressing roller 25 shown in FIG. 11(b) is a pipe 28 with flocks 29 on the surface thereof, and a uniform density plate 26 is formed in the non-flocked portion.

Thereby, effects similar to those in the example described above can be obtained.

Next, the document pressing roller 25 in FIG. 11(c) is an example of the pipe 28 itself, and can reduce deflection due to its own weight. In the previous three examples, the surface arc of the uniform density plate 26 is the radius from the center of rotation,
Even during the rotation of the document suppressing roller 25, the scattering state due to the rotation does not change, so there is no need to make the timing particularly strict.

Next, the document suppressing roller 2 in FIGS. 11(d) and (e)
5 is an example in which the uniform density plate 26 is a flat surface, and in order to perform shading correction regardless of whether it is rotating or stationary, the timing of each shading correction or the stationary position must be strictly controlled so that the plane direction does not change. There is a need to.

Next, the document suppressing roller 26 shown in FIG. 11(f) has a plurality of uniform density plates 26 provided on the circumference. By providing multiple control points for the timing of shading correction in this way, restrictions on the rotation angle of the document pressing roller 25 can be relaxed, thereby reducing the waiting time for shading correction even if the roller diameter is increased. be able to.

Next, the document suppressing roller 25 in FIG. 12 is belt-shaped unlike the previous ones.

In this case, a flat uniform density plate 26 is attached to a part of the belt 30.
By forming this, the timing of shading correction is not strict.

As described above, by providing the uniform density plate 26 for shading correction in the recess formed on the outer peripheral surface of the document pressing roller 25, the uniform density plate 26 is prevented from coming into contact with the document 1. This prevents the uniform density plate 26 from becoming dirty or damaged.

The invention having the first effect includes a displacement amount detecting means for detecting the amount of displacement of the original from the reading position, and a solid-state image sensor is moved along the optical axis of the imaging lens according to the amount of displacement of the original detected by the displacement amount detecting means. Since the solid-state image sensor moving means for moving the solid-state image sensor in the optical axis direction is provided, the effective reading pixels of the solid-state image sensor are moved by moving the solid-state image sensor in the optical axis direction according to the amount of displacement of the document detected by the displacement amount detection moving means. The area can be changed, and thereby, duplication or omission of image information during reading can be eliminated and accurate reading can be performed.

The second invention provides a document detection means for detecting one end of the JM document, and presses the back surface of the JM document based on a signal detected by the document detection means. Since it is located at the connection part and is movably attached,
By pressing the back surface of the document with this document pressing member, it is possible to eliminate overlaps and omissions at the connecting portion of the document, thereby making it possible to perform accurate reading.

A third aspect of the invention is to provide a document detection means for detecting one end of the document, and to position a document pressing body that presses the back surface of the document based on a signal detected by the document detection means at the reading connection portion of the document. Since a concave part for shading correction is formed in a part of the outer peripheral side of this document presser, by pressing the back side of the document with the document presser, it is possible to prevent overlaps or omissions at the connection part of the S. This makes it possible to perform accurate reading. Also, by using the recess formed in the document pressing body as a shading correction plate, this shading correction plate does not come into contact with the document, making it possible to perform shading correction. This eliminates the possibility of the plate becoming dirty or being damaged, thereby extending the life of the shading correction plate and allowing stable shading correction to be performed at all times.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the first invention, Fig. 2 is a side view thereof, Fig. 3 is a perspective view of displacement detection means, and Fig. 4 is a filter that transmits only infrared rays for detecting displacement. FIG. 5 is a plan view showing a modification of FIG. 1, FIG. 6 is a plan view showing an embodiment of the second invention, and FIG. 7 shows the state at the connection part. 8 is a plan view showing a modification thereof, FIG. 9 is a plan view showing an embodiment of the third invention, FIG. 10 is a plan view showing the state when the original is inserted, and FIG. Figure 11 (a) (b) (c) (d) (e)
(f) is a front view showing a modified example of the shading correction plate;
FIG. 12 is a plan view showing the situation when a belt-shaped conveyance roller is used, FIG. 13 is a perspective view showing a conventional image reading device, FIG. 14 is an explanatory diagram showing the image reading method, and FIG.
FIG. 5 is a perspective view showing another conventional example, and FIG. 16 is a side view showing a conventional example using a shading correction plate. 1... Original, 4, 5... Imaging lens, 6, 7...
Solid-state image sensor, 16...Displacement amount detection means, 21...
Imaging lens, 22...solid-state imaging device, 24...document detection means. 25... Original pressing body, 26... Concave portion, C... Reading connection portion, P... Reading position, S... Main scanning direction amount Applicant: Ricoh Co., Ltd.
151 tχ Figure 37” m ＼ 07-Procedural Amendment (Ki) 1. Display of the case Japanese Patent Application No. 63-59999 2, Name of the invention Image reading device 3, Person making the amendment Relationship to the case Patent applicant address 1-3-6-4 Nakamagome, Ota-ku, Tokyo, Agent
Patent Application No. 107 No. 1983-59999 Amendment Regarding this application, the description and drawings are amended as follows. Note 1: The scope of claims is amended as shown in the attached sheet. (Claim 3 has been deleted.) 2. In the specification,
"Figure 13" on the 7th line of page 3 is corrected to "Figure 9." 3. In the specification, page 4, line 8, r.
Correct to "Figure 0". 4. In the specification, "Figure 15" on page 6, line 6 is replaced with "Figure 1
5. Delete the text from page 7, line 16 to page 9, line 1 in the specification. 6. Delete the text from page 10, line 7 to page 11, line 2 in the specification. 7. Delete the text from page 16, line 5 to page 19, line 4 in the specification. 8. Delete the text from page 20, line 5 to page 21, line 1 in the specification. 9. In the specification, page 21, line 11 to page 21, line 2
"Figure 9 is a side view." in the 0th line is corrected as follows. "FIG. 9 is a perspective view showing a conventional image reading device, FIG. 10 is an explanatory diagram showing its image reading method, and FIG. 11 is a perspective view showing another conventional example." 10, in the specification, Delete "26... recess," on the 4th line of page 22. 11. Figures 9 to 12 are deleted from the drawings. 12. In the drawings, Fig. 13 is corrected to Fig. 9 as shown in the attached sheet.6 13. In the drawings, Fig. 14 is corrected to Fig. 10 as shown in the attached sheet. 14. In the drawings, Figure 15 has been corrected to Figure 11 as shown in the attached sheet. 15. Delete Figure 16 from the drawings. Attachment 2, Claims/1. Image information formed along the main scanning direction of a document set at a reading position is divided and reduced by an imaging lens to form a document image, and this formed document image is placed in parallel with the imaging lens. An image reading device that reads image information of the original by detecting it with a solid-state image sensor includes a displacement detection means for detecting the amount of displacement of the original from a reading position, and a displacement detection means for detecting the amount of displacement of the original from the reading position, and a displacement detection means for detecting the displacement of the original from the reading position, and An image reading device comprising: solid-state image sensor moving means for moving the solid-state image sensor in the optical axis direction of the imaging lens according to the amount of displacement. 2. Image information formed along the main scanning direction of a document set at a reading position is divided and reduced by an imaging lens to form a document image, and the formed document images are placed side by side on the imaging lens. In an image reading device that reads image information of the document by detecting it with a solid-state image sensor,
A document detecting means for detecting one end of the document is provided, and a document pressing body that presses a back surface of the document based on a signal detected by the document detecting means is located at a reading connection part of the document and is movable. An image reading device characterized by being attached.

Claims (1)

[Claims] 1. Image information formed along the main scanning direction of a document set at a reading position is divided and reduced by an imaging lens to form a document image, and this formed document image is In an image reading device that reads image information of the document by detecting it with a solid-state image sensor arranged in parallel with an imaging lens,
a displacement amount detection means for detecting the amount of displacement of the original from a reading position; and a displacement amount detection means for moving the solid-state image sensor in the optical axis direction of the imaging lens in accordance with the amount of displacement of the original detected by the displacement amount detection means. An image reading device comprising a solid-state image sensor moving means for moving a solid-state image sensor. 2. Image information formed along the main scanning direction of a document set at a reading position is divided and reduced by an imaging lens to form a document image, and the formed document images are placed side by side on the imaging lens. In an image reading device that reads image information of the document by detecting it with a solid-state image sensor,
A document detecting means for detecting one end of the document is provided, and a document pressing body that presses a back surface of the document based on a signal detected by the document detecting means is located at a reading connection part of the document and is movable. An image reading device characterized by being attached. 3. Image information formed along the main scanning direction of the original set at the reading position is divided and reduced by an imaging lens to form an original image, and the formed original images are placed side by side on the imaging lens. In an image reading device that reads image information of the document by detecting it with a solid-state image sensor,
A document detecting means for detecting one end of the document is provided, and a document pressing body that presses a back surface of the document based on a signal detected by the document detecting means is located at a reading connection part of the document and is movable. 1. An image reading device, wherein a concave portion for shading correction is formed in a part of the outer peripheral side surface of the document pressing member.