JPH06319018A - Image reader - Google Patents

Abstract

PURPOSE:To read a document with N-pixel resolution in a main scanning direction by a line image sensor which has N/2 pixels. CONSTITUTION:A control part 16 controls the direction of an exciting current applied to an electromagnet 22 to rotate a support table 11 to a 1st position or 2nd position. An image forming lens 1 images reflected light from an image area from the center of the document in the main scanning direction to one end part on a 1st CCD image sensor 13 at the 1st position and also images reflected light from an image area from the center of the document in the main scanning direction to the other end part on a 2nd CCD image sensor 14 at the 2nd position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an imaging lens and a CC.
The present invention relates to an image reading device including a line image sensor such as a D image sensor.

[0002]

2. Description of the Related Art FIG. 12 is a schematic block diagram showing an example of a main part of a conventional image reading apparatus.

Reference numeral 1 denotes an image forming lens which constitutes a reduction optical system, and 2
Is a known CCD (Ch
arge Coupled Device) image sensor, 3 is a fluorescent lamp.

The document D is transported in the direction A by a transport mechanism (not shown), and the image surface is illuminated by the fluorescent lamp 3. The reflected light reflected by the document D is incident on the imaging lens 1 and the imaging lens 1 causes the CCD image sensor 2 to move.
An image is formed on the light receiving surface of. The CCD image sensor 2 reads an image on the main scanning line L and outputs line image data.

The number of pixels of the CCD image sensor 2 is defined by the pixel density and the width of the original to be read in the main scanning direction H. For example, when the pixel density is 8 pixels / mm, the paper width is 216 mm.
When reading the A4 size document D, the CCD image sensor 2 having 1728 pixels is required.

[0006]

In the image reading apparatus as described above, if the number of pixels of the CCD image sensor 2 is not increased as the size of the original document D to be read increases, the image of the original D is displayed at a constant pixel density. When it becomes impossible to read and the pixel density decreases, the image quality of the image reproduced by the line image data deteriorates.

However, the CCD image sensor 2 having a large number of pixels is extremely expensive, and when the CCD image sensor 2 having a large number of pixels is used, generally,
Since the aperture of the light receiving section becomes small, it is necessary to use an expensive imaging lens 1 having a high MTF (modulation transfer function) value and high resolution. Therefore, there is a problem that an image reading device capable of reading a large-sized document D becomes expensive.

An object of the present invention is to provide an image reading device for reading an original with N pixels in the main scanning direction by a line image sensor having N / 2 pixels.

[0009]

In order to solve the above-mentioned problems, the first means of the present invention is provided with an image forming lens for forming an image of reflected light from the image plane of the original, and the image forming lens forms an image. In an image reading apparatus for reading an image on a main scanning line with the number of pixels of N (even) pixels by reflected light, the two line image sensors having the number of pixels of N / 2 and the imaging lens are supported. A first position at which the image forming lens forms an image of reflected light from a first image region from the center of the image surface in the main scanning direction to one end on one of the line image sensors, or the image forming lens forms an image surface. Of the second image area from the center in the main scanning direction to the other end of the second image area are imaged on the other line image sensor, and the supporting table is rotated to a second position.

Further, the second means arranges the light receiving surface of the one line image sensor so as to be orthogonal to the optical axis of the imaging lens at the first position, and the other line image sensor. The light receiving surface of the first image area is arranged so as to be orthogonal to the optical axis of the imaging lens at the second position, and the original is bent to hold the first image area parallel to the light receiving surface of one of the line image sensors. In addition, a document supporting means for holding the second image area in parallel with the light receiving surface of the other line image sensor is provided.

Further, the third means is provided with an image forming lens for forming an image of reflected light from the image surface of the original, and the image on the main scanning line is formed into N (even) pixels by the reflected light formed by the image forming lens. In an image reading device that reads with the number of pixels
/ 2 pixel line image sensor, supporting the line image sensor and the imaging lens,
Rotate the optical axis of the imaging lens to different 2 on the main scanning line.
And a support table for moving to a position.

Further, the fourth means is characterized in that it comprises document supporting means for curving the document to hold the image surface at an equal distance from the center of rotation of the support table.

Further, the fifth means is provided with an image forming lens which forms an image of the reflected light from the image surface of the original, and the image on the main scanning line is formed into N (even number) pixels by the reflected light formed by the image forming lens. In an image reading device that reads with the number of pixels
/ 2 pixel line image sensor, supporting the line image sensor and the imaging lens,
And a support table for linearly moving in parallel with the image plane to move the optical axis of the imaging lens to two different positions on the main scanning line.

Further, in a sixth means, a drive mechanism for moving the support table moves the support table by applying a magnetic force to the permanent magnet arranged on one of the support table and the apparatus main body and the permanent magnet. And an electromagnet.

[0015]

According to the above-mentioned first means, the two line image sensors each having N / 2 pixels and the imaging lens are supported to rotate to the first position or the second position. With the table, one line image sensor reads the image of the first image area from the center in the main scanning direction to one end on the original image surface, and the other line image sensor from the center in the main scanning direction to the other end. The image in the second image area is read.

Further, according to the second means, one line image sensor whose light receiving surface is orthogonal to the optical axis of the imaging lens at the first position, and the optical axis of the imaging lens at the second position. The other line image sensor whose light receiving surface is orthogonal to
One of the one side and the other side is held by the document supporting means for holding the first area of the image surface parallel to the light receiving surface of one line image sensor and the second area parallel to the light receiving surface of the other line image sensor. It is possible to prevent the reflected light image formed on the light receiving surface of the line image sensor from being distorted.

According to the third means, the number of pixels is N /
The line image sensor having two pixels and the support table that supports and rotates the line image sensor and the imaging lens causes the line image sensor to read the image of the document at two different positions on the main scanning line.

Further, according to the fourth means, the image of the reflected light formed on the light receiving surface of the line image sensor may be distorted by the document supporting means for holding the image surface at the same distance from the rotation center of the supporting table. To be prevented.

According to the fifth means, the number of pixels is N /
The line image sensor having two pixels and the support table that linearly moves in parallel with the image plane while supporting the line image sensor and the imaging lens prevent the reflected light image formed on the light receiving surface from being distorted. The line image sensor reads the image of the document at two different positions on the main scanning line.

Further, according to the sixth means, a supporting table provided with a permanent magnet arranged on one of the supporting table or the apparatus main body and an electromagnet for moving the supporting table by applying a magnetic force to the permanent magnet. The driving mechanism of (1) causes the electromagnet to exert an attractive force or a repulsive force on the permanent magnet in accordance with the direction of the electric current, thereby moving the support table to a predetermined position.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 11, the members described with reference to FIG. 12 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a side sectional view showing an essential part of a first embodiment of an image reading apparatus of the present invention, and FIGS. 2 and 3 show a first embodiment.
It is a top view of the important section in an example.

Reference numeral 11 is a support table for supporting the imaging lens 1 via a holder 12, and 13 and 14 are a pair of first and second CCs.
D image sensor, 21 is a permanent magnet fixed to the lower surface of the support table 11, and 22 is an apparatus main body that pivotally supports the support table 11.
It is an electromagnet fixed at 15.

The electromagnet 22 is excited by being applied with a DC exciting current by the control unit 16, and applies a repulsive force or an attractive force to the permanent magnet 21 in accordance with the direction of the exciting current. When the electromagnet 22 applies a repulsive force to the permanent magnet 21, the support table 11
Rotates clockwise and the magnetic force causes the permanent magnet 21 to come into contact with the stopper 17 to be held in the first position shown in FIG. When the electromagnet 22 applies an attractive force to the permanent magnet 21, the support table 11 rotates counterclockwise, and the permanent magnet 21 is pressed against the electromagnet 22 by the magnetic force,
It is held in the second position shown in FIG. Support table 11
Is configured such that the rotation center line is orthogonal to the optical axis S of the imaging lens 1 and passes through the center of the imaging lens 1.
As the support table 11 rotates, the optical axis S of the imaging lens 1 moves on the main scanning line L of the document D.

Further, as shown in the explanatory view of FIG.
Is W in the main scanning direction H, and when the image reading device reads the document D at a pixel density of d (pixels / mm) in the main scanning direction H, the document D is dW in the main scanning direction H.
The number of pixels is read. At this time, the first and second C
The number of pixels of the CD image sensors 13 and 14 is dW /
Two pixels are used. Here, dW / 2 is an integer.

The image forming lens 1 receives the reflected light from the image area D1 from the center of the document D in the main scanning direction H to one end at the first position on the light receiving surface 13a of the first CCD image sensor 13.
At the second position, the reflected light from the image area D2 from the center of the document D in the main scanning direction H to the other end is imaged on the light receiving surface 14a of the second CCD image sensor 14. Further, the first CCD image sensor 13 has a light receiving surface 13a which is the first
Is arranged at a position orthogonal to the optical axis S of the imaging lens 1 at the position of, and the second CCD image sensor 14 has a light receiving surface 14
a is arranged at a position orthogonal to the optical axis S of the imaging lens 1 at the second position.

FIG. 5 is a timing chart of input / output signals during image reading in the first embodiment.

The control unit 16 reverses the direction of the exciting current applied to the electromagnet 22 in synchronization with the control pulse having a constant cycle.
The support table 11 moves to the first position when the exciting current flows in the positive direction and moves to the second position when it flows in the negative direction, and is held at each position.
Further, the control unit 16 controls the conveyance motor that drives the conveyance mechanism for the document D in synchronization with the odd-numbered output control pulses.
A conveyance motor drive pulse is output to (not shown), and the document D is moved in the A direction by a movement amount equal to the pixel pitch in the sub scanning direction.

Further, the controller 16 outputs the first CCD image sensor 13 t seconds after the odd-numbered control pulse is output.
The read signal is output to the second CCD image sensor 14 t seconds after the even-numbered control pulse is output. With this read signal, the first CCD image sensor 13 reads the image area D1 and outputs the line image signal A, and the second CCD image sensor 14 reads the image area D2 and outputs the line image signal B.
Here, the time t is a time set longer than the moving time of the support table 11 and the document D.

The control unit 16 combines the line image signal A and the line image signal B into one line image signal as shown in FIG. The combined line image signal is composed of dW = N pixel signals, the pixel signals of the line image signal A are arranged from the 1st to N / 2th, and from the (N / 2 + 1) th to the Nth The pixel signals of the line image signal B are arranged. As a result, the document D is read by the number of pixels of N pixels in the main scanning direction by the first and second CCD image sensors 13 and 14 having the number of pixels of N / 2.

FIG. 7 is a plan view showing another example of the essential parts of the first embodiment of the present invention.

The document support base 18 bends the document D near the main scanning line L so that the image area D1 of the document D is moved to the first CC.
The light receiving surface 13a of the D image sensor 13 is held in parallel, and the image area D2 of the document D is held parallel to the light receiving surface 14a of the second CCD image sensor 14. As a result, the receiving surface 1
Since the reflected light from the image areas D1 and D2 is prevented from being distorted in 3a and 14a, the image of the document D can be accurately read by the two first and second CCD image sensors 13 and 14.

FIG. 8 is a plan view showing the main part of the second embodiment of the present invention.

Reference numeral 31 is a CCD image sensor, and 32 is a support table that supports the imaging lens and the CCD image sensor 31.

Here, when the document D has a width W in the main scanning direction H and the apparatus reads the document D with a pixel density of d (pixels / mm), the CCD image sensor 31 has a pixel number of dW /.
Two pixels (integer pixels) are used. Also support table
32 is rotated to a first position or a second position by a drive mechanism including a permanent magnet and an electromagnet as in the first embodiment, and is held at each position, and the rotation center line of the support table 32 is It passes through the center C of the imaging lens 1.

As the support table 32 rotates, the optical axis S of the imaging lens 1 moves on the main scanning line L of the original D, and the support table 32 moves from the first position or the second position to the other position. The optical axis S on the main scanning line L is moved by (dW) to ¹ mm on the main scanning line L. The imaging lens 1 forms an image of the reflected light of the document D on the light receiving surface 31a of the CCD image sensor 31 at the first position and the second position, respectively.
Reads the image on the main scanning line L while the image forming lens 1 is held at the first position to read the line image signal A
And when the imaging lens 1 is held at the second position, the image on the main scanning line L is read and the line image signal B is output. Here, if (dW) ~ ¹ = P, the CCD image sensor 31 is 2P as shown in FIG.
An image is read at a pixel pitch of mm, and line image signals A and B composed of dW / 2 pixel signals are output to a control unit (not shown). The control unit combines the pixel signal of the line image signal A and the pixel signal of the line image signal B into a line image signal in which the pixel signals are alternately arranged. As a result, the CCD image sensor 31 having a pixel number of dW / 2 pixels can obtain a line image signal equivalent to that when the document D is read by the CCD image sensor having a pixel number of dW pixels.

FIG. 10 is a plan view showing another example of the essential parts of the second embodiment of the present invention.

The document support table 33 bends the document D near the main scanning line L and holds the image surface of the document D at an equal distance from the center C of the imaging lens 1. This makes the light receiving surface
Since the reflected light imaged at 31a is prevented from being distorted, the image of the document D can be accurately read by the CCD image sensor 31.

FIG. 11 is a plan view showing an essential part of the third embodiment of the present invention. Members corresponding to the members described with reference to FIG. 8 are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 41 is a support table for supporting the imaging lens 1 and the CCD image sensor 31, and the support table 41.
Is moved to a first position and a second position in the main scanning direction H by a drive mechanism including a permanent magnet and an electromagnet, and is held at each position. Here, the moving stroke of the support table 41 is set to (dW) to ¹ mm. Similar to the second embodiment, the CCD image sensor 31 outputs the line image signals A and B shown in FIG. 9 at the first position and the second position, respectively. The line image signal of FIG. 9 in which the pixel signal of A and the pixel signal of line image signal B are alternately arranged is synthesized.

In the third embodiment, since the support table 41 moves in parallel with the document D, the document D need not be bent or curved as in the first and second embodiments.
By holding the document D parallel to the main scanning direction,
It is possible to prevent the image from being distorted on the light receiving surface 31a of the CCD image sensor 31.

[0042]

As described above, according to the first means of the present invention, one line image sensor reads the image in the first image area of the document with the number of N / 2 pixels, and the other line is read. When the image sensor reads the image of the second area of the document with the number of pixels of N / 2, the number of pixels is N /
The image of the document D can be read with the number of pixels of N pixels by using two line image sensors of 2 pixels.

Further, according to the second means, it is possible to prevent the image of the reflected light formed on the light receiving surfaces of the one and the other line image sensors from being distorted, so that the one and the other line image sensors can detect the original. The image of D can be read accurately.

According to the third means, the number of pixels is N /
The 2 pixel line image sensor is different on the main scanning line.
By reading the image of the original at the position, the number of pixels is N /
The image of the original can be read with the number of pixels of N pixels by using the line image sensor of 2 pixels.

Further, according to the fourth means, the image of the reflected light formed on the light receiving surface of the line image sensor is prevented from being distorted, so that the line image sensor can accurately read the image of the original. it can.

According to the fifth means, the image of the reflected light formed on the light receiving surface is prevented from being distorted, and the line image sensor reads the image of the document at two different positions on the main scanning line. By using a line image sensor having N / 2 pixels, it is possible to accurately read an image of an original with N pixels.

Further, according to the sixth means, the electromagnet exerts an attractive force or a repulsive force on the permanent magnet in accordance with the direction of the electric current to move the support table to a predetermined position. Since the torque is transmitted, the support table can be accurately moved to a predetermined position without using a complicated mechanism such as a gear train.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a main part of a first embodiment of an image reading apparatus of the present invention.

FIG. 2 is a plan view of a main part of the first embodiment.

FIG. 3 is a plan view of a main part in the first embodiment.

FIG. 4 is an explanatory diagram of an image area on a document.

FIG. 5 is a timing chart of input / output signals during image reading in the first embodiment.

FIG. 6 is an explanatory diagram of a line image signal in the first embodiment.

FIG. 7 is a plan view showing another example of the main part of the first embodiment of the present invention.

FIG. 8 is a plan view showing a main part of the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of line image signals in the second and third embodiments.

FIG. 10 is a plan view showing another example of the main part of the second embodiment of the present invention.

FIG. 11 is a plan view showing an essential part of the third embodiment of the present invention.

FIG. 12 is a schematic configuration diagram showing an example of a main part of a conventional image reading apparatus.

[Explanation of symbols]

1 ... Imaging lens, 11, 32, 41 ... Support table, 13 ...
1st CCD image sensor, 14 ... 2nd CCD image sensor, 18, 33 ... Original support, 21 ... Permanent magnet, 22
… Electromagnet, 31… CCD image sensor, D… Original,
H ... Main scanning direction, L ... Main scanning line, S ... Optical axis.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 1/028 Z 8721-5C 1/387 4226-5C

Claims (6)

[Claims] 1. An image having an image forming lens for forming an image of reflected light from a document image surface, and an image on a main scanning line is read by N (even number) pixels by the reflected light formed by the image forming lens. In the reading device, two line image sensors each having N / 2 pixels and the image forming lens are supported, and the image forming lens has a first image sensor from the center of the image plane in the main scanning direction to one end. The first position where the reflected light from the image area is imaged on one of the line image sensors, or the imaging lens reflects the reflected light from the second image area from the center of the image plane in the main scanning direction to the other end. An image reading apparatus, comprising: a support table that rotates to a second position where an image is formed on the other line image sensor. 2. The light receiving surface of the one line image sensor is arranged so as to be orthogonal to the optical axis of the imaging lens at the first position, and the light receiving surface of the other line image sensor is the first light receiving surface. It is arranged so as to be orthogonal to the optical axis of the imaging lens at the position 2, and the original is bent to hold the first image area parallel to the light receiving surface of one line image sensor, and 2. The image reading apparatus according to claim 1, further comprising a document supporting unit that holds the image area of the above in parallel with the light receiving surface of the other line image sensor. 3. An image provided with an image forming lens for forming an image of reflected light from an image surface of an original, and an image on a main scanning line is read by the number of N (even) pixels by the reflected light formed by the image forming lens. In the reading device, a line image sensor having N / 2 pixels and a line image sensor and the imaging lens are supported, and the optical axis of the imaging lens is rotated to two different positions on the main scanning line. An image reading apparatus comprising: a support table that is moved to the front. 4. The image reading apparatus according to claim 3, further comprising a document supporting unit that curves the document and holds the image surface at an equal distance from the center of rotation of the support table. 5. An image provided with an image forming lens for forming an image of reflected light from an image surface of an original, and an image on a main scanning line is read by N (even) pixels by the reflected light formed by the image forming lens. In the reading device, a line image sensor having N / 2 pixels and the line image sensor and the imaging lens are supported, and the optical axis of the imaging lens is moved linearly in parallel with the image plane. An image reading apparatus comprising: a support table that is moved to two different positions on a main scanning line. 6. A drive mechanism for moving the support table includes a permanent magnet arranged on one of the support table and the apparatus main body, and an electromagnet for applying a magnetic force to the permanent magnet to move the support table. The image reading apparatus according to claim 1, 2, 3, 4, or 5.