JP3123640B2 - Scanning optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device, and more particularly, to a scanning optical device applied to image input such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, a scanning optical device used in a copier or the like scans the entire surface of an original placed on a cover glass by driving a mirror that is movably supported, and scans the original. The light from the CCD is guided to an imaging lens via a mirror to form an image on a light receiving surface of a CCD line sensor. The document information read by the CCD line sensor is converted into a digital signal, buffered and output to a memory (not shown), and the contents of the document are reproduced.

[0003] Further, there is conventionally known an image forming apparatus which forms an electrostatic latent image by directly exposing a photosensitive member made of a photoconductive material to an image without using a CCD line sensor, and develops the electrostatic latent image with toner. Have been.

[0004]

However, in the conventional scanning optical apparatus, since the cover glass on which the original is placed is formed in a horizontal plane, when scanning a thick book or the like, FIG. As shown in the drawing, the vicinity of the center of the book 80 is separated from the cover glass 82, and there is a drawback that blur and shadow occur in this portion.

The present invention has been made in view of such circumstances, and provides a scanning optical apparatus capable of capturing not only ordinary flat originals but also thick books without blurring or shadowing. With the goal.

[0006]

According to the present invention, in order to achieve the above object, an original placed on a glass plate is scanned from below, and light from the original surface is irradiated with a predetermined light through an imaging lens. In a scanning optical device for forming an image on an image forming surface, a cover glass in which two flat glass plates are foldably connected to each other;
Cover glass bending means for bending two flat glass pieces into a roof shape, detecting means for detecting a bending angle of the cover glass bent by the cover glass bending means or a value corresponding to the bending angle, and the cover glass A first mirror that is movably supported below and reflects light from the original surface, and a movement of the first mirror that scans the original placed on the cover glass at a constant speed. First mirror control means for controlling the speed, position detection means for detecting the position of the first mirror, and light from the document surface reflected by the first mirror to the image forming lens And the folding angle detected by the detecting means or a value corresponding to the bending angle, and the position of the first mirror detected by the position detecting means. The way that the distance to the imaging plane is constant, and characterized in that and a second mirror controller for controlling the moving speed of the second mirror from.

According to the present invention, the cover glass is formed by connecting the two flat glass plates in a bendable manner. Therefore, even when the original is a thick book, the cover glass is bent in accordance with the thickness. By adjusting the angle and making the central part of the spread of the book coincide with the bent portion, it is possible to prevent the central part of the book from rising from the cover glass. By driving the second mirror so that the distance from the document surface to the predetermined image forming surface is constant, an image can be captured without blurring or shadowing at the center of the book. In addition, by using the cover glass in a flat shape without bending it, it is possible to cope with an ordinary flat original.

Further, according to the bending angle of the cover glass,
By adjusting the document scanning speed, a normal document image can be read.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a scanning optical device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an image reading device in which a scanning optical device according to the present invention is used. The image reading apparatus shown in FIG. 1 mainly includes a cover glass 12 that can be bent and a first lead screw 14 that drives the cover glass 12.
And a first mirror 1 for reflecting light from the original surface in the horizontal direction
6, a second lead screw 18 for driving the first mirror 16, a second mirror block 20 for turning back the original light reflected by the first mirror, and a second mirror block 2
A third lead screw 22 that drives 0 horizontally.
An imaging lens 24 for condensing the original light guided through the second mirror block 20, a CCD line sensor 26 disposed on the imaging surface of the imaging lens 24, and the first, second and third leads The control unit 28 controls the driving of the screws 14, 18, 22 and the like.

The cover glass 12 is formed by connecting the end faces of two flat glass plates 30 and 31 so as to be able to be bent. The cover glass 12 can be bent into a roof shape using a center connecting shaft 32 as a bending axis. θ can be freely adjusted. The ends of the cover glass 12 are rotatably connected to nuts 34 and 35, respectively, and the nuts 34 and 35 are screwed to the first lead screw 14.

The first lead screw 14 is driven by a stepping motor 36, and the stepping motor 36 is controlled by the control unit 28. A normal right screw is formed on the right side of the first lead screw 14 in the drawing, and a reverse screw (left screw) is formed on the left side. When the first lead screw 14 rotates, the nuts 34 and 35 are formed. Move in a direction approaching or moving away from each other, and the bending angle θ of the cover glass 12 is adjusted.

A position detecting slit 38 is formed in the nut 35, and a photo interrupter (position detector) 39 for detecting the position detecting slit is provided in the casing of the apparatus. The detection data of the detector position is notified to the control unit 28. The home position of the cover glass 12 is detected by the position detector 39, and the pulses of the stepping motor 36 are counted based on the home position to detect the position of the end of the cover glass 12. Based on the detection of the position of the end of the cover glass 12, the bending angle θ of the cover glass 12, the inclination angle of the cover glass 12 with respect to the horizontal plane, and the like can be obtained.

The first mirror 16 is fixed to a mirror mount 40 at an angle of 45 degrees with respect to a horizontal plane with respect to a reflection surface. The mirror mount 40 is screwed to the second lead screw 18 and the second lead screw 1
The motor 8 is driven by a motor 42, which is controlled by the control unit 28. And the second
The rotation of the lead screw 18 causes the first mirror 1
Reference numeral 6 slides in the left-right direction (scanning direction) in the figure.

A slit 43 for position detection is formed in the mirror mount 40, and a photo interrupter 44 for detecting the slit 43 for position detection is provided in the casing of the apparatus. The photo interrupter 44
Is sent to the control unit 28. The home position of the first mirror 16 is detected by the photo interrupter 44, and the motor 42
The position of the first mirror 16 is detected by detecting the rotation direction, rotation speed, rotation amount, and the like of the first mirror 16.

The second mirror block 20 is vertically
Including two mirrors 46 and 47 opposed at an angle of 0 degrees,
The two mirrors 46 and 47 are positioned and fixed to a common mirror mount 48. Upper mirror 4
Reference numeral 6 reflects the light from the first mirror 16 downward, and the lower mirror 47 reflects the light from the mirror 46 in the horizontal direction and guides the light to the imaging lens 24.
The input optical axis of the mirror 46 and the output optical axis of the mirror 47 are formed in parallel.

The mirror mount 48 of the second mirror block 20 is screwed to the third lead screw 22,
The lead screw 22 is driven by a motor 50. The motor 50 is controlled by the control unit 28. When the third lead screw 22 rotates, the second mirror block 20 moves to the left and right in the figure to move the optical path length to the light receiving surface of the CCD line sensor 26. Is adjusted. The drive control of the second mirror will be described later.

A position detecting slit 52 is formed in the mirror mount 48, and a photo interrupter 53 for detecting the position detecting slit 52 is provided in the casing of the apparatus. The photo interrupter 53
Is sent to the control unit 28. The home position of the second mirror block 20 is detected by the photo interrupter 53, and the rotation direction, the rotation speed, the rotation amount, and the like of the motor 50 are detected based on the home position.
The position of the mirror block 20 is detected.

FIG. 2 is a plan sectional view of the drive mechanism of the cover glass shown in FIG. 1, and FIG. 3 is a side view of a main part thereof. As shown in the figure, the left and right flat glass plates 30 and 31 are held by cover glass frames 56 and 57, respectively, and their end faces are connected at the center C so as to be freely bent. The guide bar 62 and the first lead screw 1 are provided in the casing 60.
4 are disposed in parallel with each other, and movers 64 and 65 slidably supported on the guide bar 62 and nuts 34 and 35 screwed to the first lead screw 14 allow the cover glass 12 to be moved. The four corners are rotatably supported.

Since the first lead screw 14 is formed with a left and right reverse screw, when the first lead screw 14 is rotated by the motor 36, the cover glass 12 is rotated.
Is bent from the center with the center C as a bending axis, and the inclination angle of the cover glass 12 with respect to the horizontal plane can be freely changed. FIG. 4 is a plan sectional view of a driving mechanism of the first mirror and the second mirror block shown in FIG. 1, and FIG. 5 is a side view of a main part thereof.

As shown in FIGS. 4 and 5, in the casing 60, two drive mechanisms are provided in upper and lower stages, the upper drive mechanism drives the first mirror 16, and the lower drive mechanism is provided in the lower drive mechanism. The second mirror block 20 is driven. The upper drive mechanism has a guide bar 66 and a second lead screw 18 disposed in the casing 60 in parallel with the cover glass drive mechanism shown in FIGS. Mover 6 slidably supported
8 and a nut 7 screwed to the second lead screw 18
By 0, a long mirror mount 40 is supported. And the first on the 45 degree inclined surface of the mirror mount 40
The mirror 16 is fixed.

In the lower drive mechanism, similarly to the first drive mechanism described above, a guide bar (not shown) and a third lead screw 22 are disposed in parallel in the casing 60, and are mounted on the guide bar. The elongated mirror mount 48 is supported by a slidably supported mover and a nut 72 screwed to the third lead screw 22. The mirror mount 48 holds two long mirrors 46 and 47 facing each other at an angle of 90 degrees as shown in FIG.
The light reflected by the first mirror 16 is reflected downward 90 degrees by the mirror 46, and further reflected 90 degrees horizontally by the mirror 47, thereby turning the optical path back.

On this optical axis, an imaging lens 24 and a CCD line sensor 26 are arranged. These are all accommodated in a casing 60 formed with a light shielding structure. Next, the driving operation of the mirror will be described with reference to FIG. By modeling the scanning optical device shown in FIG.
The following XY coordinate system is set.

In order to keep the distance from an arbitrary position P (x ₁ , y ₁ ) on the document surface to the light receiving surface of the CCD line sensor 26, the following equation (1) may be satisfied.

[0024]

Y ₁ + (x ₁ −x ₂ ) + (x ₃ −x ₂ ) = L (constant value) (1) where x ₂ is the second mirror block 20 (mirror 46,
X-coordinate position x ₃ of 47) is a constant L indicating the X-coordinate position of the light receiving surface of the CCD line sensor 26 is a constant Here, the arbitrary point on the document surface P (x _1, y _1), the following equation ( 2), (3)

[0025]

When x ₁ ≧ 0, y ₁ = − (y ₀ / x ₀ ) x ₁ + y ₀ (2)

[0026]

When x ₁ <0, y ₁ = (y ₀ / x ₀ ) x ₁ + y ₀ (3) where (x ₀ , y ₀ ) is obtained when the bending angle of the cover glass 12 is set. Since there is a relation of a fixed constant, the position x ₂ of the second mirror block 20 (mirrors 46 and 47) is expressed by the following equation (4) or (5).

[0027]

## EQU4 ## When x ₁ ≧ 0, x ₂ = （× [L− (y ₀ / x ₀ ) x ₁ + y ₀ + x ₁ + x ₃ ] (4)

[0028]

When x ₁ <0, the control may be performed so as to satisfy x ₂ = １ ／ × [L + (y ₀ / x ₀ ) x ₁ + y ₀ + x ₁ + x ₃ ] (5). That is, the following equation in relation to the driving speed of the driving speed of the second mirror block 20 (dx ₂ / dt) a first mirror 16 (dx ₁ / dt) (6) or (7),

[0029]

[Formula 6] When x ₁ ≧ 0 dx ₂ / dt = 1/2 × (dx ₁ / dt) [1- (y ₀ / x ₀ )] (6)

[0030]

When x ₁ <0, dx ₂ / dt = 1/2 × (dx ₁ / dt) [1+ (y ₀ / x ₀ )] (7) Next, the operation of the image reading apparatus with the scanning optical device according to the present invention configured as described above will be described.

First, the stepping motor 36 is driven according to the thickness of the book 80 to be read, and an appropriate bending angle is formed on the cover glass 12. Then, as shown in FIG. 7, the book 80 is opened and the center thereof is placed so as to match the bent portion of the cover glass 12. After the book is placed on the cover glass 12, the folding angle of the cover glass 12 may be automatically adjusted.

As described above, the central portion of the spread of the book 80 is matched with the bent portion of the cover glass 12, so that the central portion of the book 80 can be prevented from floating from the cover glass 12. Thereafter, the first mirror 16 is moved at a constant speed V while irradiating the light of a light source lamp (not shown) toward the document surface.
It moves at 1 (= dx ₁ / dt) and scans the entire document surface. Light from the document surface is horizontally reflected by the first mirror 16 and enters the second mirror block 20. The original light incident on the mirror 46 of the second mirror block 20 is reflected downward by the mirror 46 and guided to the imaging lens 24 via the mirror 47. Then, the original image condensed by the imaging lens 24 is received by the CCD line sensor 26 disposed on the imaging surface of the imaging lens and is photoelectrically converted. The image information of the document image photoelectrically converted by the CCD line sensor 26 is digitized, stored in a memory, and guided to a printing unit (not shown) to reproduce the document image.

At this time, the second mirror block 20
According to the original scanning movement of the first mirror 16, the above equation (6) is obtained.
Or (7) to the speed of the relationship shown V2 (= dx ₂ / dt) are driven, the optical path length from the document surface to the light receiving surface of the CCD line sensor 26 is kept constant. Therefore, an image can be captured without causing blur or shadow at the center of the double-page spread of the book 80. By setting the bending angle of the cover glass 12 to 0 degree, a normal flat original can be handled.

The original scanning speed (the driving speed V1 of the first mirror) according to the bending angle of the cover glass 12.
By adjusting, a normal original image can be read. That is, as the bending angle θ of the cover glass 12 shown in FIG. 1 increases, the inclination angle of the cover glass 12 with respect to the horizontal plane increases. The image can be read.

In the above embodiment, the case of driving the second mirror block 20 has been described. Instead of driving the second mirror block 20, or together with the driving of the second mirror block 20, the imaging lens 24 and the second mirror block 20 are driven. CCD
It is also conceivable to drive the line sensor 26 back and forth along the optical axis so that the optical path length from the document surface to the light receiving surface of the CCD line sensor 26 is kept constant.

In the above embodiment, the light from the document surface is imaged on the light receiving surface of the CCD line sensor, and
The case where the original is read by the CD line sensor has been described. However, the present invention is not limited to this. Alternatively, an electrostatic latent image may be formed on the image. In this case, the second mirror and the like are controlled so that the distance from the document surface to the drum surface is constant.

Further, in the above embodiment, the second mirror block 20 is constituted by the two mirrors 46 and 47,
The case where the mirror block 20 is driven so as to keep the optical path length from the document surface to the light receiving surface of the CCD line sensor 26 constant has been described, but the first mirror 16 is constituted by one mirror 82 as shown in FIG. The mirror 82 may be driven so that the optical path length from the document surface to the light receiving surface of the CCD line sensor 26 is kept constant. In this case, if necessary, the angles of the first mirror 16 and the mirror 82 are appropriately adjusted.

[0038]

As described above, according to the scanning optical apparatus of the present invention, the cover glass is formed by connecting two flat glass plates in a bendable manner. The parts can be matched and the central part of the book can be prevented from lifting off the cover glass. And
During scanning of the original, the second mirror is driven so that the distance from the original surface to the light receiving surface of the line sensor is constant according to the bending angle of the cover glass. Images can be captured without shadows.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image reading apparatus to which a scanning optical device according to the present invention is applied.

FIG. 2 is a plan sectional view of a cover glass driving mechanism.

FIG. 3 is a side view of a main part of a drive mechanism of the cover glass.

FIG. 4 is a plan sectional view of a driving mechanism of a first mirror and a second mirror block.

FIG. 5 is a side view of a main part of a drive mechanism of a first mirror and a second mirror block.

FIG. 6 is a coordinate diagram for explaining a mirror driving operation.

FIG. 7 is a side view showing a document placement state according to the embodiment of the present invention;

FIG. 8 is a main part configuration diagram showing another embodiment of the present invention.

FIG. 9 is a side view showing a document placement state in a conventional scanning optical device.

[Explanation of symbols]

 12, 80 ... cover glass 14 ... first lead screw 16 ... first mirror 18 ... second lead screw 20 ... second mirror block 22 ... third lead screw 24 ... imaging lens 26 ... CCD line sensor 28 ... control unit 30 Reference numeral 31, 31 Flat glass 34, 35 Nut 36, 42, 50 Motor 38, 43, 52 Position detection slit 39, 44, 53 Photointerrupter 62, 66 Guide bar 80 Book (document)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/04-1/207

Claims (2)

(57) [Claims] 1. A scanning optical device which scans a document placed on a glass plate from below and forms light from a document surface on a predetermined image forming surface via an image forming lens. A cover glass in which flat glass is foldably connected; a cover glass bending means for bending the two flat glass into a roof shape; and a bending angle of the cover glass bent by the cover glass bending means. Or a detecting means for detecting a value corresponding to the bending angle; a first mirror movably supported below the cover glass and reflecting light from the original surface; and a first mirror mounted on the cover glass. First mirror control means for controlling the moving speed of the first mirror so as to scan the original at a constant speed, position detecting means for detecting the position of the first mirror, and the first mirror A second mirror that reflects the light from the document surface reflected by the second mirror and guides the light to the imaging lens; a bending angle detected by the detecting means or a value corresponding to the bending angle; and a position detected by the position detecting means. Second mirror control means for controlling the moving speed of the second mirror so that the distance from the document surface to the image forming surface is constant based on the position of the first mirror. A scanning optical device. 2. The apparatus according to claim 1, wherein said first mirror control means changes a moving speed of said first mirror so as to read a normal document image in accordance with said bending angle. Scanning optics.