JPH0686018A - Color image reader - Google Patents

Abstract

PURPOSE:To simplify constitution by reducing the number of line buffers to be used. CONSTITUTION:A cylindrical lens 18 is arranged on an optical path between an original platen 11 and an image forming lens 14 and the three lines of RGB of a color CCD image sensor 15 are imageformed on the same line of an original 12 on the original platen 11. Since the position of image information read at one reading timing is identical for RGB and the deviation of RGB lines is absorbed as in the past, a lot of the line buffers are not required and the constitution is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading device equipped with a color CCD image sensor.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a color image reading apparatus of this type has a fluorescent tube 3 which is a linear light source for illuminating a document 2 placed on a document table 1, and a reflection from the document 2. An image forming lens 4 for forming an image of light, a CCD image sensor 5 for photoelectrically converting the image information formed by the image forming lens 4 in the line direction, and a mirror for changing the optical path as necessary. 6 and 7, an optical system unit 8 that holds these optical components in an appropriate positional relationship, a drive system that moves the optical system unit 8 to perform sub-scanning, and a housing 9. There is also a type of device that moves the document table 1 instead of moving the optical system unit 8. The optical system unit 8 includes the CCD image sensor 5
Outputs the image information for one line by main-scanning the original 2 line by line, and the optical system unit 8 moves in the sub-scanning direction perpendicular to the line direction of the original 2 after the scanning of one line is completed. Next line is CCD image sensor 5
Scans and reads the entire image information of the original 2.

The CCD image sensor 5 used in this type of color image reading apparatus reads a color image by color separation of a 3-line on-chip filter type. This 3 line on-chip filter type CC
D image sensor has 3 CCDs in 1 package
It has a reading line, and filters of three colors for color separation are arranged in each line, and the intervals of the three lines are equal pitch and unequal pitch.

There are a line-sequential reading method, an area-sequential reading method, and a dot-sequential reading method as the reading method of the original 2 by the CCD image sensor 5 having such a configuration. Of these, the line-sequential reading method and the field-sequential reading method are generally used. The former is R (red), G (green), and B (blue) for each line read in the sub-scanning direction.
This is a method of outputting image information for primary colors, and the number of times of reading one original is one. On the other hand, the latter frame-sequential reading method is a method of reading one color at a time three times per original and outputting one color at a time. Therefore, it can be said that the former, which requires only one reading, has a higher reading speed than the latter, in which one document is read three times.

[0005]

However, the former line-sequential reading method has a problem that many line buffers are required to absorb the distances between the lines of the three colors of the CCD image sensor. This is because, in the case of the line-sequential system, the image reading device needs to send the image information of the same line on the original for three colors in succession, while the CCD image sensor, This is because the image information at the position in the sub-scanning direction that is different by the number of lines in the CCD is output, and it is necessary to correct it. Therefore, since the three lines are not located at the same position inside the CCD image sensor, the position of the image information read at one read timing is set to R when sub-scanning from R to B and G is performed. For example, B is 10 lines and G is 20 lines.
The line will be misaligned. For this reason, G is read last, so G has 10 lines for B and R for G.
The image information for 20 lines is accumulated and output with a delay, which requires a large number of line buffers.

An object of the present invention is to solve such a conventional problem, and an object thereof is to provide a simple color image reading apparatus having a structure in which the number of line buffers used is small.

[0007]

In order to achieve the above object, the present invention has a cylindrical lens disposed on the optical path between a document table and an imaging lens, and has three RGB lines of a color CCD image sensor. Is imaged on the same line of the original on the original table.

[0008]

Therefore, according to the present invention, the reading optical system is moved line by line in the sub-scanning direction, and the color CCD is moved.
Image sensor reading timing is 1 at a time
When the scanning is repeated, the three lines of the color CCD image sensor form an image on the same line with respect to the original, so that the position of the image information read at one reading timing is R.
The GB is also the same, and it is not necessary to use a large number of line buffers to absorb the deviation of the RGB lines as in the conventional case, and the configuration of the device can be simplified.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. It differs from the conventional example shown in FIG. 4 in that a cylindrical lens is added. In FIG. 1, 11 is a manuscript table formed of a transparent material, 12 is a manuscript placed on the manuscript table 11, 13 is a fluorescent tube for illuminating the manuscript 12 on the manuscript table 11, and 14 is an image of the manuscript 12. Imaging lens for imaging information, 1
Reference numeral 5 is a color CCD image sensor of 3-line equal pitch on-chip filter type for photoelectrically converting the image information formed by the imaging lens 14, 16 and 17 are mirrors for changing the optical path, 18 is a document table 11 and Imaging lens 1
4 is a cylindrical lens disposed on the optical path between the color CCD image sensor 15 and the color CCD image sensor 15.
The line is imaged on the same line of the original 12 on the original table 11. Reference numeral 19 is an optical system unit that holds these optical components in an appropriate positional relationship, and 20 is a housing of the apparatus.

FIG. 2 shows the plane structure of the color CCD image sensor 15, wherein 15a is an R line for reading the red color component of the color image, 15b is a G line for reading the green color component of the color image, and 15c is a blue color image of the color image. It is the B line that reads the component. The R line 15a is arranged at a position separated from the G line 15b by 10 lines, and the B line 15c is arranged at a position separated from the G line 15b by 10 lines. However,
The arrangement of the lines is an example, and the present invention is not limited to this.

FIG. 3 is a principle diagram of the optical system in the above embodiment, in which 12 is an original, 18 is a cylindrical lens, and 1 is a cylindrical lens.
Reference numeral 4 is an imaging lens, and 15 is a color CCD image sensor. The color CCD image sensor 15 is arranged so that its light receiving surface is located at the focal position of the imaging lens 14, and the cylindrical lens 18 is arranged so that the original 12 is located at the focal position. The cylindrical lens 18 has power only in the sub-scanning direction, and has three lines 15a of the color CCD image sensor 15,
Images 15b and 15c are formed on the same line of the original 12.

Next, the operation of the above embodiment will be described with reference to FIG. Document platen 1 by fluorescent tube 13 which is a line light source
When the original 12 on 1 is illuminated, the reflected light from the original 12 is redirected by mirrors 16 and 17, and an image is formed on the line of the color CCD image sensor 15 by the imaging lens 14 and photoelectrically converted. At this time, color CC
The reading position on the object (original) side in the sub-scanning direction where images are formed on the three RGB lines of the D image sensor 15 is focused on the optical center by the cylindrical lens 18,
Three RGB lines come to line up on one line. Sub-scan is
Set the optical system unit 1 in the direction perpendicular to the main scanning direction.
This is done by moving line by line.
The line distance usually corresponds to the pixel pitch in the main scanning direction of the CCD image sensor. If this is performed once for each reading timing of the CCD image sensor 15, the portion on the original 12 that forms an image on the color CCD image sensor 15 will be shifted by one line. At this time, since the three RGB lines are imaged on the same line with respect to the original 12, the positions of the image information read at one read timing are the same for both RGB and the main scanning. The image information of the document 12 is output as surface data by a combination of sub-scanning.

As described above, according to the above-mentioned embodiment, the three lines of RGB of the color CCD image sensor 15 are set by the cylindrical lens 18 arranged on the optical path between the document table 12 and the imaging lens 14. Since the image is formed on the same line of the original 12 on 11, the position of the image information read at one read timing is the same as that of RGB, and there are many positions to absorb the deviation of the RGB line as in the conventional case. No line buffer is required, and the configuration of the device is simplified.

Although the original table 11 is fixed and the optical system unit 19 is integrally moved to perform sub-scanning in the above embodiment, the optical system unit is fixed and the original table 11 is fixed. The present invention can also be applied to a device of the type in which the sub-scanning is performed by moving the lens, or a device of which a part of the optical component is fixed and the other part is moved to perform the sub-scanning. You can

[0015]

According to the present invention, as is apparent from the above-mentioned embodiment, the cylindrical lens is arranged on the optical path between the original table and the image forming lens, and the RGB of the CCD image sensor is arranged.
The above three lines are imaged on the same line of the original on the original table, and the position of the image information read at one read timing is the same as RGB. A large number of line buffers are not required to absorb the deviation of the line buffer, the number of line buffers used can be reduced, and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color image reading apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of a color CCD image sensor in the same device.

FIG. 3 is a principle diagram of an optical system in the device.

FIG. 4 is a schematic configuration diagram of a conventional color image reading device.

[Explanation of symbols]

 11 Document Plate 12 Document 13 Fluorescent Tube 14 Imaging Lens 15 Color CCD Image Sensor 16, 17 Mirror 18 Cylindrical Lens 19 Optical System Unit 20 Housing

Claims (1)

[Claims] 1. An optical path between a document table and an imaging lens,
A color image reading device provided with a cylindrical lens arranged so that three RGB lines of a color CCD image sensor are imaged on the same line of a document on a document table.