JP2002118731A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that adjusts the read start position of an image and a white reference board, so as to enhance the effects of shading correction. SOLUTION: Read processing of an image is divided into steps. Number of steps, equivalent to a distance deviated an image read start position, is written in a memory 110 via an interface and the scanning line is adjusted to bring the image read start position closer to a read start position 3a, that is the ideal read start position. The read start position of the white reference board 109 is also shifted by the same number of steps and adjusted, by reading the deviation (the number of steps) of the image read start position that is written in the memory 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus for simultaneously adjusting an image reading start position and a white reference plate reading start position.

[0002]

2. Description of the Related Art In recent years, image reading apparatuses such as copiers, scanners, and facsimile machines have been reduced in cost due to advances in image technology, and have been widely used not only in offices but also in homes. Along with this, the demand for higher image quality is rapidly increasing, and a line sensor, which is an image sensor in which point sensors (pixels) are arranged one-dimensionally and the light intensity distribution in that direction is detected by electrical scanning or parallel output. The importance of improving the quality of sensors is also increasing.

One of the typical line sensors is CC.
There is a D (Charge Coupled Device) line sensor, and the CCD line sensor is a one-dimensional array of photodiodes and charge transfer units, and sequentially transfers photoexcited charges accumulated in the photodiodes in the line direction. , And outputs a linear light intensity distribution. Also, CC
The D-line sensor obtains a two-dimensional image in combination with scanning of an object or a sensor in a direction perpendicular to the sensor axis as represented by a facsimile.

For the purpose of maintaining high image quality by the line sensor as described above, there is a shading correction for correcting an output signal of the line sensor in a bit unit in a line sensor output signal processing. It corrects variations in the sensitivity of the line sensor, non-uniformity of illumination, differences in light amount between the center and both ends due to the optical system, and insufficient light amount around the lens.

In shading correction, illumination OF
The output of the CCD line sensor in the state of F is a black reference signal, the illumination is ON, and the output of the CCD line sensor when the illumination is reflected on a white reference plate for shading correction is a white reference signal.

[0006] The shading correction is a correction process based on the difference data between the black reference signal and the white reference signal, creating bit-by-bit all pixel correction data, and based on the data.

However, there has been a problem that the relative positions of the white reference plate, the detection sensor, the detection member, and the like are shifted due to positional accuracy, temperature change, and the like, and the reading start position of the white reference plate fluctuates.

As an invention for solving the above problems, an image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 08-149299 (hereinafter referred to as Conventional Example 1) and Japanese Patent Application Laid-Open No.
There is an image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 0929159 (hereinafter referred to as Conventional Example 2).

In Conventional Example 1, a gate signal for defining shading data is generated based on a predetermined reference, and the read area of the white reference plate is not changed even if the image reading start position is changed. An invention for setting the effective range of a plate is described.

[0010] Further, the prior art 2 describes an invention in which a white reference plate for obtaining a reference output is maintenance-free, and always accurate shading correction is possible. In the invention described in Conventional Example 2, the reading start position can be adjusted by freely moving the white reference plate forward and backward and switching the optical path.

[0011]

However, a CCD image sensor and a lens are optically adjusted using a jig, and a unit having the optically adjusted CCD image sensor, lens, lens receiving base, and the like is mounted on an actual machine. ,
In an image reading apparatus that adjusts the reading start position, if only the reading portion of the document is adjusted and the reading start position of the white reference plate is not adjusted, the scan line is shifted from the white reference plate when performing shading correction. In some cases, it is impossible to perform appropriate white reference correction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image reading apparatus that adjusts the reading start positions of an image and a white reference plate to improve the effect of shading correction. I do.

[0013]

In order to achieve the above object, the invention according to claim 1 is an image reading apparatus which creates a white reference signal based on light reflected from a white reference plate when performing shading correction. The adjustment of the reading start position of the image and the adjustment of the reading start position of the white reference plate are simultaneously performed.

Therefore, according to the first aspect of the present invention, the adjustment of the reading start position of the image and the adjustment of the reading start position of the white reference plate are simultaneously performed, so that the scan line reads the range of the white reference plate. The effect of shading correction can be improved.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the image reading start position detecting means for detecting an image reading start position, and the image reading start position detecting means detecting the image reading start position. Image reading start position measuring means for measuring the distance from the read start position of the image to the normal reading start position of the image, image distance storing means for storing the distance measured by the image reading start position measuring means, and image distance Image reading start position adjusting means for adjusting the image reading start position based on the distance stored by the storage means, and first image reading position adjusting means for adjusting the reading start position of the white reference plate based on the distance stored by the image distance storing means. And a white reading start position adjusting means.

According to the second aspect of the present invention, the distance from the detected image reading start position to the normal image reading start position is stored, and the image and the white reference plate are stored based on the distance. By adjusting the reading start position,
The scan line reads the range of the white reference plate, and the effect of shading correction can be improved.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the image distance storage means divides a read portion of the image into a predetermined length along the sub-scanning direction, and The number of steps corresponding to the distance measured by the image reading start position measuring means is stored, with the read portion of the image divided for each step as a step.

Therefore, according to the third aspect of the present invention, the read portion of the image is divided into predetermined lengths in the sub-scanning direction, and the read portion of the image divided for each predetermined length is detected as a step. By storing the number of steps corresponding to the distance from the image reading start position to the normal image reading start position, the image and white reference plate reading start positions can be easily adjusted.

According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the adjustment of the reading start position of the image and the adjustment of the reading start position of the white reference plate are performed. Are performed independently of each other.

According to the fourth aspect of the present invention, the adjustment of the image reading start position and the adjustment of the white reference plate reading start position are performed independently of each other. By independently adjusting the read start position of the white reference plate, the read start position of the image and the white reference plate can be adjusted even when the deviation amounts of the read start positions of the image and the white reference plate are different. It is possible to execute the shading correction accurately and improve the effect of the shading correction.

According to a fifth aspect of the present invention, in the image reading apparatus of the fourth aspect, the white reading start position detecting means for detecting the reading start position of the white reference plate and the white reading start position detecting means are provided. A white reading start position measuring means for measuring a distance from the detected reading start position of the white reference plate to a normal reading start position of the white reference plate, and a white storing the distance measured by the white reading start position measuring means. Distance storage means;
And a second white reading start position adjusting means for adjusting the reading start position of the white reference plate based on the distance stored by the white distance storage means.

According to the fifth aspect of the present invention, the distance from the detected reading start position of the white reference plate to the normal reading start position of the white reference plate is stored, and based on the distance, the white reference plate is stored. By adjusting the reading start position of the plate, the scan line reads the range of the white reference plate, and the effect of shading correction can be improved.

According to a sixth aspect of the present invention, in the image reading apparatus of the fifth aspect, the white distance storage means includes:
The read portion of the white reference plate is divided into predetermined lengths along the sub-scanning direction, and the read portion of the white reference plate divided for each predetermined length corresponds to a distance measured by the white reading start position measuring means, as a step. The number of steps is stored.

According to the present invention, the read portion of the white reference plate is divided into predetermined lengths along the sub-scanning direction, and the read portion of the white reference plate divided for each predetermined length is used as a step. , From the detected reading start position of the white reference plate,
By storing the number of steps corresponding to the distance to the normal reading start position of the white reference plate, the reading start position of the white reference plate can be easily adjusted.

[0025]

FIG. 1 is a diagram showing the configuration of an image reading apparatus having a differential mirror type driving system according to an embodiment of the present invention. Hereinafter, the configuration of the image reading apparatus adopting the differential mirror system according to the present embodiment and the functions of each part will be described with reference to FIG.

The image reading apparatus 100 according to the present embodiment
Are at least a reduction optical system, a differential mirror type driving system, and a color sensor type CCD image sensor 101.
And a contact glass 102, a white reference plate 109, a memory 110, and units 111 to 11
And 3.

The unit 111 includes a light source 103,
A first carriage 106, and the unit 112 includes:
The unit 113 has a mirror 104 and a second carriage 107, and the unit 113 has a CCD image sensor 101, a lens 105, and a jig 108.

The CCD image sensor 101 employs the color sensor system as described above,
The original 1 is set on the surface 02. Light source 103
Irradiates the original 1 with light, and the reflected light
The light is incident on the lens 105 via the light emitting element 104.

In the lens 105, the reflected light is reduced and introduced into the three-line CCD image sensor 101. The reflected light introduced into the CCD image sensor 101 is converted into an electric signal (photoelectric conversion) and then subjected to image processing. The CCD image sensor 101 is subjected to R (red), G (green), and B (blue) filters, and performs color separation at the same time.

Further, the first carriage 106 moves forward at a constant speed v, and the second carriage 107 moves forward following the first carriage 106 at a speed v / 2, which is half the speed of the first carriage 106. . As a result, the optical path length 2 is maintained at a constant value, and the original 1 set on the surface of the contact glass 102 is optically scanned.

The jig 108 includes the CCD image sensor 10
1 and the lens 105 are adjusted to a reading start position 3a which is an ideal image reading start position.
Reference numeral 9 is used to generate a white reference signal, and uses the output of the CCD image sensor 101 based on the reflected light as a white reference signal. Further, the image and the reading start position of the white reference plate 109 are written in the memory 110.

When the unit adjusted as described above is mounted on an actual machine, a reading start position 3b which is an erroneous image reading start position due to variations in parts such as the mirror 104.
, The scan line may deviate from the reading start position of the white reference plate 109, and the shading correction may not work effectively.

Therefore, when the reading start position of the image is adjusted, the reading start position of the white reference plate 109 is also adjusted at the same time, so that the shading correction can be effectively executed.

A method of adjusting the reading start position of the image and the reading start position of the white reference plate 109 will be described below. It is assumed that the deviation between the image reading start position and the reading start position of the white reference plate 109 is the same.

The read portion of the image is divided into a plurality of steps, and the number of steps (the number of steps) corresponding to the distance deviating from the image reading start position is written into the memory 110 via the interface, and the scan line is written. Adjustment is performed to bring the image reading start position closer to the ideal reading start position 3a.

The shift amount (the number of steps) of the reading start position of the image written in the memory 110 is read, and the reading start position of the white reference plate 109 is moved and adjusted by the same number of steps.

FIG. 2 is a diagram showing the configuration of an image reading apparatus having an optical unit type driving system according to an embodiment of the present invention. Hereinafter, the configuration of the image reading apparatus employing the optical unit system according to the present embodiment and the function of each part will be described with reference to FIG.

The image reading apparatus 200 of this embodiment includes at least the contact glass 102 and the white reference plate 109.
, A memory 110, and a unit 114. The unit 114 includes the CCD image sensor 101.
, A light source 103, a mirror 104, a lens 105,
have.

The image reading device 100 of the differential mirror type in the image reading device 200 of the optical unit type of the present embodiment.
The difference between the CCD image sensor 101 and the optical system such as the light source 103, the mirror 104 and the lens 105
Are incorporated in the unit 114, and the unit 114
The point is that the original surface is scanned to read an image by moving itself.

In the image reading apparatus 200 of the optical unit type, when the reading start position of the image is shifted and the scan line is deviated from the reading start position of the white reference plate 109, the image reading apparatus 100 of the differential mirror type is used. The scan line is adjusted in a similar manner to approach the read start position 3a which is an ideal image read start position.

The difference between the image reading start position and the ideal image reading start position, the difference between the reading start position of the white reference plate 109 and the ideal reading start position of the white reference plate 109, and Are not equal, the adjustment of the reading start position of the image and the adjustment of the reading start position of the white reference plate 109 are performed independently.

[0042]

As described above, according to the first aspect of the present invention, the adjustment of the scanning start position of the image and the adjustment of the scanning start position of the white reference plate are performed at the same time, so that the scan line is adjusted to the white reference. By reading the range of the plate, the effect of shading correction can be improved.

According to the second aspect of the invention, the distance from the detected image reading start position to the normal image reading start position is stored, and the image and the white reference plate are stored based on the distance. By adjusting the reading start position, the scan line reads the range of the white reference plate, and the effect of shading correction can be improved.

According to the third aspect of the present invention, the read portion of the image is divided into predetermined lengths in the sub-scanning direction, and the read portion of the image divided for each predetermined length is set as a step.
By storing the number of steps corresponding to the distance from the read start position of the detected image to the normal read start position of the image, the read start position of the image and the white reference plate can be easily adjusted. Become.

According to the fourth aspect of the present invention, the adjustment of the image reading start position and the adjustment of the white reference plate reading start position are performed independently of each other, so that the adjustment of the image reading start position and the adjustment of the image reading start position are performed independently. By independently adjusting the read start position of the white reference plate, the read start position of the image and the white reference plate can be adjusted even when the deviation amounts of the read start positions of the image and the white reference plate are different. It is possible to execute the shading correction accurately and improve the effect of the shading correction.

According to the fifth aspect of the present invention, the distance from the detected reading start position of the white reference plate to the normal reading start position of the white reference plate is stored, and based on the distance, the white reference plate is stored. By adjusting the reading start position of the plate, the scan line reads the range of the white reference plate, and the effect of shading correction can be improved.

According to the present invention, the read portion of the white reference plate is divided into a predetermined length along the sub-scanning direction,
The number of steps corresponding to the distance from the detected reading start position of the white reference plate to the normal reading start position of the white reference plate is stored with the read portion of the white reference plate divided by the predetermined length as a step. This makes it possible to easily adjust the reading start position of the white reference plate.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image reading apparatus having a differential mirror type driving system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an image reading apparatus having an optical unit type driving system according to an embodiment of the present invention.

[Explanation of symbols]

 1 Document 2 Optical path length 3a, 3b Reading start position 100, 200 Image reading device 101 CCD image sensor 102 Contact glass 103 Light source 104 Mirror 105 Lens 106 First carriage 107 Second carriage 108 Jig 109 White reference plate 110 Memory 111-114 unit

Claims (6)

[Claims] 1. An image reading apparatus for generating a white reference signal based on light reflected from a white reference plate when performing shading correction, comprising: adjusting an image reading start position and reading the white reference plate. And an image reading apparatus for performing the adjustment at the same time. 2. An image reading start position detecting means for detecting a reading start position of the image, and an image reading start position from the image reading start position detected by the image reading start position detecting means to a normal reading start position of the image. Image reading start position measuring means for measuring a distance; image distance storing means for storing the distance measured by the image reading starting position measuring means; and the image based on the distance stored by the image distance storing means. Image reading start position adjusting means for adjusting a reading start position of the first white reading start position adjusting means for adjusting a reading start position of the white reference plate based on the distance stored by the image distance storing means; The image reading apparatus according to claim 1, comprising: 3. The image distance storage means divides a read portion of an image into a predetermined length along a sub-scanning direction,
3. The image reading device according to claim 2, wherein the number of the steps corresponding to the distance measured by the image reading start position measuring means is stored, with the read portion of the image divided by a predetermined length as a step. apparatus. 4. The image according to claim 1, wherein adjustment of the reading start position of the image and adjustment of the reading start position of the white reference plate are performed independently. Reader. 5. A white reading start position detecting means for detecting a reading start position of the white reference plate, and a normal state of the white reference plate based on the reading start position of the white reference plate detected by the white reading start position detecting means. A white reading start position measuring means for measuring a distance to a proper reading start position; a white distance storing means for storing the distance measured by the white reading start position measuring means; and a white distance storing means for storing the distance measured by the white distance storing means. The image reading apparatus according to claim 4, further comprising: a second white reading start position adjusting unit that adjusts a reading start position of the white reference plate based on a distance. 6. The white distance storage means divides a read portion of the white reference plate into a predetermined length along the sub-scanning direction, and uses the read portion of the white reference plate divided for each predetermined length as a step, 6. The image reading apparatus according to claim 5, wherein the number of the steps corresponding to the distance measured by the white reading start position measuring means is stored.