JP2001144899A - Picture reader adjusting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the focusing method of a reducing and reading optical system capable of satisfactorily adjusting an output signal in the main scanning direction and the sub-scanning direction of an original. SOLUTION: In the case of focusing in a main scanning direction, patterns arrayed at regular intervals in the longitudinal direction of a line sensor 6 for reading originals are read by an image forming lens. In the case of focusing in the sub-scanning direction, a reading member 10 consisting of a translucent material is movably inserted in an optical path connecting an original surface and the lens 5 and this member 10 is properly moved to read patterns arrayed at regular intervals in the direction orthogonal to the longitudinal direction of the sensor 6 through the lens 5. As the member 10, a parallel flat glass whose upper/lower surfaces are parallel with each other is provided in a state of being freely inclinable in the direction orthogonal to the main-scanning direction and in a state of being capable of finely adjusting its inclination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting an image reading apparatus, and more particularly to a method for adjusting the focus of a reduction optical system in an image reading apparatus provided in a scanner, a copying machine, a facsimile, or the like.

[0002]

2. Description of the Related Art As an optical system constituting an image reading apparatus in a scanner, a copying machine, a facsimile, or the like, a reflected light of an original illuminated by an illumination system is reduced by an imaging lens to a line sensor for reading an image (original). 2. Description of the Related Art A reduction reading optical system for imaging is known.

Conventionally, in focus adjustment in this reduced reading optical system, an adjustment pattern in which ordinary black and white lines orthogonal to the longitudinal direction of a line sensor are arranged at regular intervals on a sheet of paper is placed on an original mounting plate of an image reading apparatus. By setting the imaging lens and the line sensor while changing the position of the imaging lens and the line sensor while reading the pattern with the reduction reading optical system, an operation of adjusting the reduction ratio and the output of the line sensor to a favorable state is performed. ing.

[0004]

However, in the above focus adjustment method, only an output in the so-called main scanning direction in the longitudinal direction of the line sensor can be seen, so that the imaging lens is used with the position A shown in FIG. And the position of the line sensor may be adjusted, and the resolving power in the off-axis (main scanning direction) on the axis in the drawing satisfies the threshold for conforming to the specifications, but the off-axis (sub-scanning) Direction), the threshold for conforming to the specifications cannot be satisfied, which causes problems such as poor resolution in the sub-scanning direction. In addition, when the above-described poor resolving power in the sub-scanning direction occurs, it is necessary to perform focus adjustment again, which makes the focus adjustment operation extremely complicated. As shown in FIG. 9, the resolving power in the main scanning direction and the resolving power in the sub-scanning direction are represented by MTF% (the ratio of the reproduction of the contrast of the pixels of the document).

As a focus adjustment method for setting the resolution to a high level, there is a method disclosed in Japanese Patent Application Laid-Open No. 8-214112. However, in this focus adjustment method, it is necessary to know the performance of the imaging lens in advance without performing focus adjustment by looking at the MTF output in the sub-scanning direction. If the imaging performance varies due to variations within the tolerance, there is a problem that the focus cannot be adjusted to a position having good resolution in both the main scanning direction and the sub-scanning direction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to focus on a reduction reading optical system in an image reading apparatus capable of favorably adjusting output signals in a main scanning direction and a sub scanning direction. It is to provide an adjustment method.

[0007]

According to a first aspect of the present invention, there is provided a method for adjusting an image reading apparatus, wherein a document set on a document placing surface is illuminated by an illumination system, and reflected light from the document is imaged by an imaging lens. A focus adjustment method in an image reading apparatus in which a reduced image is formed and this formed original image is photoelectrically converted by an original reading line sensor, wherein a first array is arranged at regular intervals in a longitudinal direction of the line sensor. A first adjustment operation of setting a focus adjustment document on which a pattern is written on the document mounting surface and performing focus adjustment in a main scanning direction by reading the first pattern with the imaging lens; and A focus adjustment document in which second patterns arranged at equal intervals in the direction perpendicular to the longitudinal direction of the sensor are described is set on the document placement surface, and the focus adjustment document and the document surface of the focus adjustment document are imaged. A reading member made of a translucent material capable of reading different positions of the document surface in the sub-scanning direction by movement, and inserting the reading member through the imaging lens by the reading member. And a second adjustment operation for performing focus adjustment in the sub-scanning direction by reading the second pattern.

In the present invention, for example, as shown in FIGS. 1 to 3, in the first adjustment operation, focus adjustment in which first patterns 7 arranged at equal intervals in the longitudinal direction of the line sensor 6 are described. The original 9 is set on the original placing surface (contact glass 1), and the first pattern 7 is read by the imaging lens 5 to adjust the focus of the image reading optical system in the main scanning direction.

In the second adjusting operation, the focus adjusting original 9 on which the second patterns 8 arranged at regular intervals in the direction orthogonal to the longitudinal direction of the line sensor 6 are written is placed on the original placing surface. And a light-transmissive material (light-transmitting material) capable of reading different positions in the sub-scanning direction of the original surface by moving the original in the optical path connecting the original surface of the focus adjusting original 9 and the imaging lens 5. A reading member 10 made of a material (material) is inserted, and the second member 8 is read by the reading member 10 through the imaging lens 5 to adjust the focus of the image reading optical system in the sub-scanning direction. In addition,
The first adjustment operation may be performed before or after the second adjustment operation. Further, as the focus adjusting document 9, a pattern 7 as shown in FIG.
It is efficient to use the one in which 8 are written on the same paper.

According to a second aspect of the present invention, there is provided an image reading apparatus adjusting method according to the first aspect, wherein the focus adjustment document 9 (adjustment chart) is provided at regular intervals in the longitudinal direction of the line sensor 6. It is characterized in that the arranged first patterns 7 and the second patterns 8 arranged at equal intervals in a direction orthogonal to the longitudinal direction of the line sensor 6 are written on the same original surface.

According to a third aspect of the present invention, there is provided a method for adjusting an image reading apparatus according to the first or second aspect, wherein the reading member is a parallel plate glass whose upper and lower surfaces are parallel to each other, in the main scanning direction. Characterized by using a material that can be inclined in a direction perpendicular to the direction.

According to a fourth aspect of the present invention, there is provided an image reading apparatus adjusting method according to the first or second aspect, wherein the reading member has a taper in a direction perpendicular to the main scanning direction and has a main scanning direction. It is characterized in that an object that can translate in a direction perpendicular to the direction is used.

According to a fifth aspect of the present invention, there is provided a method for adjusting an image reading apparatus according to the first or second aspect, wherein the reading member has a rotatable disk shape having a taper in a direction perpendicular to the circumferential direction. Wherein the angle of the taper continuously changes in the circumferential direction of the glass plate.

According to a sixth aspect of the present invention, there is provided a method for adjusting an image reading apparatus according to the first, second, third, fourth, or fifth aspect, wherein the image reading apparatus includes a three-line sensor as a line sensor. Characterized in that:

According to a seventh aspect of the present invention, there is provided an image reading apparatus according to the sixth aspect, wherein the focus adjustment in the sub-scanning direction is performed on only one arbitrary line.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment (Claims 1 and 2) Hereinafter, an explanation will be given using an image reading apparatus using three mirrors as an example. FIG. 1 is an explanatory diagram of the configuration of the image reading apparatus, showing a normal state before a reading member is inserted. FIG. 2 is an explanatory diagram showing a procedure for inserting the reading member according to the present invention into the image reading apparatus. FIG. 3 is a plan view of the focus adjustment chart.

In the image reading apparatus to which the (focus) adjustment method of the present invention is applied, as shown in FIG. 1, an original 2 is set on a contact glass 1 and an illumination optical system ( (Not shown) illuminates the original 2. The reflected light from the document 2 is reflected by the first mirror 3a of the first traveling body 3 and then reflected by the second mirror 4a and the third mirror 4b of the second traveling body 4, and is reflected by a reduction imaging lens 5 (hereinafter, referred to as a focusing lens). The image is formed on the original reading line sensor 6 by the image lens.

In FIG. 1, when reading the document 2 in the sub-scanning direction, the first traveling body 3 moves to the position indicated by the reference numeral 13 at the speed V, and in parallel with this, the second traveling body 4 moves in the first traveling direction. The entire original 2 is read by moving to the position indicated by the reference numeral 14 at half the speed V / 2 of the body 3.

In the adjustment of the optical system in this reading apparatus, that is, in the focus adjustment, adjustment in the main scanning direction and adjustment in the sub-scanning direction are performed as follows. When adjusting the main inspection direction, black and white patterns 7 arranged at regular intervals in the longitudinal direction of the line sensor 6 as shown in FIG.
A document having black and white patterns 8 arranged at regular intervals in the direction perpendicular to the longitudinal direction of the line sensor 6, that is, an adjustment chart 9 is set on the contact glass 1.
Then, the first traveling body 3 and the second traveling body 4 are stopped at an arbitrary position, and the monochrome pattern 7 of the adjustment chart 9 is imaged on the line sensor 6 by the imaging lens 5.

When adjusting in the sub-scanning direction,
First, the first traveling body 3 and the second traveling body 4 are moved to an arbitrary position where the monochrome pattern 8 of the adjustment chart 9 is imaged on the line sensor 6 by the imaging lens 5. Then Figure 2
As shown in FIG. 3, a reading member 10 made of a light-transmissive material, for example, ordinary optical glass is placed in the optical path between the second traveling body 4 and the imaging lens 5 in the sub-scanning direction of the original surface (see FIGS. (Left / Right direction)
The black and white pattern 8 is read by the imaging lens 5 via the reading member 10 to form an image on the line sensor 6. In this case, the change of the optical path length by the reading member 10 can be adjusted favorably in the sub-scanning direction by changing the positions of the first traveling body 3 and the second traveling body 4.

FIG. 3 shows an example of the adjustment chart 9. The number and interval of the charts (black lines) may be set arbitrarily in accordance with the adjustment of the optical system. Regarding the positional relationship between the black and white patterns 7 and 8, the pattern 8 may be arranged on the pattern 7, contrary to FIG. Further, FIG.
In the pattern 8 described above, the chart is formed continuously, but this may be intermittent. The adjustment chart 9 includes a pattern 7 arranged at regular intervals in the longitudinal direction of the line sensor 6 and a pattern 8 arranged at regular intervals in the direction orthogonal to the longitudinal direction of the line sensor 6.
Are also written on the same original surface, but if desired, an adjustment chart showing only pattern 7 and a pattern 8
It is also possible to use an adjustment chart in which only the information is indicated.

Embodiment 1 (Claim 3) In the focus adjustment method of this embodiment, when performing adjustment in the sub-scanning direction, the reading member 10 is made of parallel flat glass whose upper and lower surfaces are parallel to each other as shown in FIG. In addition, a device that can be tilted in a direction perpendicular to the main scanning direction and that can finely adjust the tilt angle is inserted. In FIG. 4, when the reading member 10 is continuously inclined from the solid line in the direction orthogonal to the main scanning as shown by the dashed line, the optical path of the light beam incident on the imaging lens 5 is changed from the solid line to the dashed line. As shown by, the position moves continuously in the sub-scanning direction, so that the adjustment in the sub-scanning direction can be performed. In this case, the optical path of the light emitted from the reading member 10 is, as shown in FIG.
To the optical path 11. This is the same in the embodiment of FIG. 5 and the embodiment of FIG. 7 described later. Note that the thickness and the inclination angle (the amount of inclination) θ of the reading member 10 may be arbitrarily set depending on the optical system to be used.

An experimental example according to this embodiment will be described. When the thickness t of the reading member 10 is 2.95 mm and the refractive index n is 1.65, the inclination angle θ is set to 3.13 °.
The variation x of the reading position in the sub-scanning direction can be set to 0.0635 mm. Therefore, a reading density of 4
It is possible to change the sub-scanning reading position by an amount corresponding to 00 dpi.

Second Embodiment (Claim 4) In the first embodiment, since the reading member 10 is a parallel plate glass, the processing is easy and good accuracy can be obtained. However, in order to incline the reading member 10 with high accuracy. Requires a complicated drive device. Therefore, in the focus adjustment method of the second embodiment, as shown in FIG. 5, the reading member 10 is a glass having a taper (inclined surface) in a direction orthogonal to the main scanning direction, and orthogonal to the main scanning direction. Insert an object that can be moved in parallel in the direction and that can finely adjust the movement position. Then, the reading member 10 is translated in a direction orthogonal to the main scanning direction from a solid line state as shown by a dashed line. As described above, since the movement of the reading member 10 is a parallel movement (linear movement), the reading member 10 can be accurately moved with a simple structure using a piezo element, for example.

The movement of the reading member 10 causes the imaging lens 5 to move.
Also moves continuously from the solid line as indicated by the dashed line, and can read different positions in the sub-scanning direction, thereby making it possible to perform adjustment in the sub-scanning direction. The angle of the taper of the reading member 10 and the amount of parallel movement can be arbitrarily set depending on the optical system used.

FIG. 5 shows an experimental example according to this embodiment. In FIG. 5, when the taper angle σ of the reading member 10 is 10 ° and the refractive index n is 1.65, the amount of movement of the reading member 10 in the sub-scanning direction is shown. By setting S to be 3.09 mm, the variation x of the reading position in the sub-scanning direction can be made 0.0635 mm. Accordingly, it is possible to change the sub-scanning reading position by an amount corresponding to the reading density of 400 dpi on the document surface.

Third Embodiment (Claim 5) In the first embodiment, the movement of the reading member 10 inserted to adjust the sub-scanning direction is a reciprocating rotation.
In this case, the movement of the reading member 10 is a vertical reciprocating movement, and both are repetitive movements, so that an output in the sub-scanning direction cannot always be obtained. Therefore, in the focus adjustment method of the third embodiment (experimental example is not shown), the reading member 10 is rotatable as shown in FIGS. 6A and 6B, and finely adjusts the rotation position (rotation angle). Which has a taper in a direction perpendicular to the circumferential direction, and whose taper angle (thickness of the glass plate) changes continuously in the circumferential direction of the glass plate. Insert what you have.

In this embodiment, the reading member 10 is
By rotating as shown in FIGS. 7A and 7B, the optical path of the light beam incident on the imaging lens 5 moves from the state of the solid line in FIG. 7A to the position of the dashed line in FIG. 7B. . Since the output in the sub-scanning direction is continuously obtained by continuously rotating the reading member 10 in this manner, the adjustment in the sub-scanning direction can be performed more efficiently.

Second Embodiment (Claim 6) In the first to third embodiments according to the first embodiment, the case where the number of line sensors for reading a monochrome image is one has been described. The focus adjustment method can be applied to a three-line CCD for full-color reading. For this purpose, as shown in FIG. 8, for example, three line sensors (r, g, b) having R, G, and B filters are used as document line sensors, and a reading member (not shown). Is inserted at an appropriate position in the optical path between the second traveling body 4 and the imaging lens 5, and outputs in the main scanning and sub-scanning directions in the three colors of R, G, and B in the same manner as in the first to third embodiments. Can be adjusted.

Third Embodiment (Claim 7) In the second embodiment, when adjustment in the sub-scanning direction of R, G, and B colors is performed, the adjustment becomes very complicated, and a long adjustment time is required. . In a general imaging lens, the difference in field curvature between colors in the sub-scanning direction is smaller than that in the main scanning direction. Therefore, in the focus adjustment method according to the present embodiment, focus adjustment in the sub-scanning direction is performed only on an arbitrary one line. Therefore, according to this method, there is an advantage that the adjustment in the sub-scanning direction can be made more efficient.

[0031]

As apparent from the above description, the following effects can be obtained according to the present invention. (1) Effect of the Adjustment Method According to Claim 1 In this focus adjustment method, the output in the main scanning direction is adjusted by a predetermined first adjustment operation, and the output in the sub-scanning direction is adjusted by a predetermined second adjustment operation. Since the system is configured to perform adjustment, it is possible to adjust the optical system to the focus position where the imaging lens has the best performance. The problem such as the poor resolution in the sub-scanning direction, which has been a problem, can be solved. In particular, the sub-scanning direction corresponds to the first scanning direction provided in the image reading apparatus.
In addition, since focus adjustment can be performed without driving the second traveling body, it is possible to obtain a favorable output that is free from uneven speed of these traveling bodies and an adverse effect of vibration.

(2) Effects of the adjustment method according to the second aspect As the focus adjustment original, the first pattern arranged at regular intervals in the longitudinal direction of the line sensor and the direction perpendicular to the longitudinal direction of the line sensor. Since a pattern in which the second patterns arranged at equal intervals are written on the same document surface is used, the focus adjustment operation can be performed more easily.

(3) Effect of the Adjustment Method According to Claim 3 Since the reading member is a parallel flat glass whose upper and lower surfaces are parallel to each other and inclined in a direction perpendicular to the main scanning direction, this reading member is easily processed. It can be manufactured at low cost.

(4) Effect of the Adjustment Method According to Claim 4 The reading member is a glass having a taper in a direction perpendicular to the main scanning direction, and can move in parallel in a direction perpendicular to the main scanning direction. Therefore, the driving mechanism for moving the reading member has a simple structure.

(5) Effect of the Adjustment Method According to Claim 5 The reading member is a rotatable disk-shaped glass plate having a taper in a direction perpendicular to the circumferential direction, and the angle of the taper is Since the reading member continuously changes in the circumferential direction of the glass plate, by continuously rotating the reading member about the central axis, the output signal of the sub-scanning is continuously obtained. Adjustment can be made more efficient.

(6) Effects of the Adjustment Method According to Claim 6 Since the line sensor is a three-line sensor (three-line CCD), it is possible to optimally adjust each color in both the main and sub scanning directions in a full-color reading device. This makes it possible to provide a high-precision full-color reading apparatus that can solve problems such as poor resolution in the sub-scanning direction and does not cause color reproducibility or color bleeding in the sub-scanning direction.

(7) Effect of the adjustment method according to claim 7 The focus adjustment in the sub-scanning direction in the image reading apparatus according to claim 6 is performed only on an arbitrary one line (second adjustment means) Is set to one color), the number of adjustment items is reduced, and the efficiency of the adjustment operation is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an image reading apparatus according to a first embodiment, showing a state (normal state) before a reading member is inserted.

FIG. 2 is an explanatory diagram showing a procedure for inserting a reading member into the image reading apparatus of FIG. 1;

FIG. 3 is a plan view of a focus adjustment chart.

FIG. 4 is an explanatory diagram illustrating a shape and an operation of a reading member inserted into the image reading apparatus according to the first embodiment.

FIG. 5 is an explanatory diagram illustrating a shape and an operation of a reading member inserted into the image reading apparatus according to the second embodiment.

FIG. 6 illustrates a shape of a reading member according to the third embodiment.
(A) is a perspective view, (b) is a BB line sectional view of (a).

FIG. 7 is an operation explanatory view of the reading member of FIG. 6;

FIG. 8 is an explanatory diagram of a configuration of an image reading apparatus according to a second embodiment, showing a state (normal state) before a reading member is inserted.

FIG. 9 is a diagram illustrating a problem of a focus adjustment method in a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contact glass 2 Original 3 First running body 3a 1st mirror 4 2nd running body 4a 2nd mirror 4b 3rd mirror 5 Imaging lens (reduction imaging lens) 6 Line sensor 7 Black and white pattern 8 Black and white pattern 9 Adjustment chart Reference Signs List 10 Reading member 11 Optical path to line sensor 13 Stop position of first traveling body 14 Stop position of second traveling body

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H107 AA02 AB12 AB19 CA01 2H108 AA01 CB01 EA51 5C051 AA01 BA03 DB01 DB21 DC04 DE22 DE23 5C072 AA01 BA02 BA04 DA01 RA12 RA18

Claims (7)

[Claims] A document set on a document placing surface is illuminated by an illumination system, and reflected light from the document is reduced and imaged by an image forming lens, and the formed document image is photoelectrically converted by a document reading line sensor. A focus adjustment method in an image reading apparatus configured to perform conversion, wherein a focus adjustment document on which first patterns arranged at equal intervals in a longitudinal direction of the line sensor are written is set on the document mounting surface. A first adjustment operation for performing focus adjustment in the main scanning direction by reading the first pattern with the imaging lens, and a second adjustment operation arranged at regular intervals in a direction orthogonal to a longitudinal direction of the line sensor. A document for focus adjustment on which a pattern is written is set on the document placing surface, and is moved in the optical path connecting the document surface of the focus adjustment document and the imaging lens, so that a difference in the sub-scanning direction of the document surface is caused. A focus adjustment in the sub-scanning direction by inserting a reading member made of a translucent material capable of reading a position and reading the second pattern through the imaging lens by the reading member. An adjustment method for an image reading apparatus, comprising: an adjustment operation. 2. A first pattern arranged at regular intervals in a longitudinal direction of the line sensor as a document for focus adjustment, and a second pattern arranged at regular intervals in a direction orthogonal to the longitudinal direction of the line sensor. 2. The method according to claim 1, wherein a pattern written on the same document surface is used. 3. The reading member according to claim 1, wherein the reading member is a parallel plate glass whose upper and lower surfaces are parallel to each other, and can be inclined in a direction orthogonal to the main scanning direction. The adjustment method of the image reading device according to the above. 4. The reading member according to claim 1, wherein the reading member is a glass having a taper in a direction orthogonal to the main scanning direction, and is capable of moving in parallel in a direction orthogonal to the main scanning direction. 3. The method for adjusting the image reading device according to 1 or 2. 5. The reading member is a rotatable disk-shaped glass plate having a taper in a direction orthogonal to the circumferential direction, and the angle of the taper is continuous in the circumferential direction of the glass plate. 2. The method according to claim 1, wherein
Or the adjustment method of the image reading device according to 2. 6. The method according to claim 1, wherein the image reading device includes a three-line sensor as the line sensor. 7. An adjustment method for an image reading device according to claim 6, wherein the focus adjustment in the sub-scanning direction is performed on only one arbitrary line.