JP2001298590A - Device and method for reading image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fast read a monochrome image with an inexpensive configuration without deteriorating image quality in the case of selectively reading a color image and the monochrome image. SOLUTION: A holder 12 driven by a motor 13 holds a light source 14, reflection mirrors 15 to 18, an image forming lens 19, a half-mirror 20 a color CCD 21 (which is for a low speed and whose data rate is low), and a monochrome CCD 22 (which is for an intermediate speed and whose data rate is high). Detected light from the source 14 goes through an original G and is subsequently made incident on the lens 19 through the mirrors 15 to 18, and outgoing light from the lens 19 is made into two split beams α and β by a mirror 20. The spectrum α is inputted to the CCD 21 and the spectrum β is inputted to the CCD 22. When a manual switch 23 selects a color mode, the driving speed (scanning speed) of the holder 12 is made to be a low speed, and an output of the CCD 21 is also selected. When the switch 23 selects a monochrome mode, the driving speed of the holder 12 is made to be a fast speed, and an output of the CCD 22 is also selected.

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 an image reading method.

[0002]

2. Description of the Related Art Image processing by a computer, particularly a personal computer, has been widely and generally performed, and an image reading apparatus represented by a scanner has become widespread. In an image reading device, it is necessary to convert a detection light beam (reflected or transmitted) passing through an image to be read into an electric signal. For this purpose, a device using a CCD (line sensor) as a photoelectric conversion element has been widely used. ing. Japanese Patent Application Laid-Open No. 8-149368 discloses that two CCDs are used to cope with a difference in the size of an image to be read.
It has been proposed to use

In order to read a color image, a color CCD is used as a CCD. This color CCD has RGB (red, green, blue) filters on its sensor chip to separate the three primary colors of light. Can be detected. A monochrome image can also be read using such a color CCD. Therefore, conventionally, a color image and a monochrome image have been read by a common color CCD. And color CCD
There are two types of color CCDs: low-speed color CCDs with low data rates for low-speed reading, and high-speed color CCDs with high data rates for high-speed reading. At present, it has not been put to practical use yet.

[0004]

Incidentally, reading a monochrome image is often required to be performed at a higher speed than reading a color image. At present, when a color image and a monochrome image are read by a common color CCD, a high-speed color CCD must be used to read a monochrome image at a medium speed higher than a normal low speed. However, a high-speed color CCD is extremely expensive, and adopting a high-speed color CCD is only required to speed up reading of a monochrome image.
This is virtually impossible in terms of cost. In addition, reading a monochrome image with a color CCD lowers the sensitivity due to the above-described filter, and is a major cause of the deterioration in the image quality of a monochrome image.

The present invention has been made in view of the above circumstances, and has as its object to be able to read a color image and a monochrome image without deteriorating the image quality with an inexpensive configuration as a whole. It is an object of the present invention to provide an image reading apparatus and an image reading method capable of reading a monochrome image at a higher speed.

[0006]

In order to achieve the above object, the following solution is adopted in the apparatus of the present invention. That is, a half mirror disposed between the imaging lens and the imaging surface of the imaging lens and configured to split the light emitted from the imaging lens into a first spectrum and a second spectrum; A color CCD provided on a first image forming surface serving as an image forming surface of the color CCD, and a data provided on a second image forming surface serving as an image forming surface of the second spectrum and higher than a data rate of the color CCD. A monochrome CCD with a rate, a mode selection unit for manually selecting a color mode for reading a color image or a monochrome mode for reading a monochrome image, and the monochrome when the monochrome mode is selected. Scanning speed changing means for making the scanning speed of the CCD faster than the scanning speed of the color CCD when the color mode is selected; and the output of the color CCD and the monochrome CCD. Of the force, there is as provided with an output selecting means for selectively outputting a signal corresponding to the mode selected by said mode selecting means.

According to the above solution, when reading a monochrome image, the image is read at a high scanning speed using a monochrome CCD which has a high data rate and does not cause a problem of image quality deterioration due to a filter, thereby deteriorating the image quality. Quick reading can be performed without causing the reading. Also, when reading a color image, lowering the scanning speed will prevent the image quality from deteriorating.
Is used, there is no problem in terms of cost.
Even if the scanning speed of the color CCD is reduced, it takes much longer time to process a color image after reading (eg, compression, storage, printing, communication, character recognition, etc.) than in the case of monochrome image processing. Considering that, even if the reading speed is reduced, there is no particular problem in terms of the entire processing time. That is, in the case of color image processing that requires three-color processing, it takes three times as long as the processing of a monochrome image. In particular, in the case of general printing as image processing, the printing process is performed using CMYK (Sepia, When four colors (Maceda, yellow, and black) are serially printed, it takes four times as long as monochrome printing. Of course, two types of CCD, color CCD and monochrome CCD
Out of the outputs, only the output corresponding to the manually selected mode is selected, so that there is no problem in the subsequent image processing (the image processing configuration common to the color CCD and the monochrome CCD). And can be).

[0008] Preferably, scanning can be performed by holding the color CCD and the monochrome CCD in a common holder and driving the holder by driving means.
In this case, the scanning is performed simultaneously by both the color CCD and the monochrome CCD. By controlling the driving means for driving the holder, the scanning speed can be changed between the color image reading and the monochrome image reading. It can be easily changed, and there is no need to provide separate scanning drive means for the color CCD and the monochrome CCD. When a medium-speed color CCD is developed, when compared with reading a color image and reading a monochrome image using this medium-speed color CCD, the cost of the present invention is still low. Is more advantageous, and as described above, the processing speed of a color image is as low as about 1/3 to 1/4 of the processing speed of a monochrome image. The present invention is also advantageous when it is desired to do so.

The scanning method may be a CCD driving method in which the color CCD and the monochrome CCD are driven and the document is fixed, or a document driving method in which the color CCD and the monochrome CCD are driven in a fixed manner to read the document. The detection light beam from the light source incident on the imaging lens may be reflected from the document or transmitted through the document as long as it passes through the document from which the image is read. Of course, the present invention can be applied as a scanner alone, but can also be applied as an image reading device for devices equipped with an image reading device, for example, various devices such as copiers and facsimile machines that need to read images.

In order to achieve the above object, the following solution is adopted in the method of the present invention. That is,
A first step of splitting outgoing light from the imaging lens into two beams, a first beam splitter and a second beam splitter, by a half mirror in front of the image forming surface; and performing color reading in color mode or monochrome image reading. A second step of manually selecting whether the mode is a monochrome mode, and a color CCD disposed on the image plane of the first spectrum and a data rate of the color CCD disposed on the image plane of the second spectrum. Both CCDs with monochrome CCDs with higher data rates
A third step of simultaneously scanning at the same time, and scanning at a higher speed when the monochrome mode is selected than at the time when the color mode is selected, and the output of the color CCD. And the monochrome CC
A fourth step of selecting an output of the CCD corresponding to the mode selected in the third step among the outputs of D;
It is provided with. According to the above solution, the same effect as the above-described device of the present invention can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a color scanner will be described below with reference to the accompanying drawings. 1 and 2, reference numeral 1 denotes a case for forming an outer frame of a scanner which is formed in a thin box shape as a whole, and an upper surface of the case 1 has a scanning glass serving as a document mounting surface over a wide area. Surface 2. Numeral 3 denotes a thin plate for holding down the original.
The scanning glass surface 2 is attached to the case 1 so as to be swingable about the mounting portion 4 and is swung to the scanning glass surface 2 in response to the swing, and the scanning glass surface 2 is largely opened to the outside. Open state.

A guide rod 11 is fixedly disposed in the case 1 in parallel with the scanning glass surface 2, and a holder 12 is slidably held on the guide rod 11. The holder 12 is driven by a motor 13 for scanning with the guide rod 11 serving as a guide.
Note that a method of driving the holder 12 by the motor 13 for scanning is well known in the related art, and a detailed description thereof will be omitted (a specific driving mechanism is not shown).

The holder 12 has one light source 14, a plurality of (four in the embodiment) reflecting mirrors 15 to 18,
One imaging lens 19, one half mirror 20,
Two CCDs 21 and 22 are fixed and held. The light source 14 irradiates the scanning glass surface 2, that is, the document surface on which the image placed on the scanning glass surface 2 is read, with the detection light beam, and among the detection light beams, the scanning glass surface 2 (document surface) Reflected light from the reflection mirror 15,
The light is sequentially incident on the imaging lens 19 through 16, 17, and 18.

The half mirror 20 is disposed between the image forming lens 19 and its image forming surface, and separates the detection light beam emitted from the image forming lens 19 into first and second two light splittings α and β. I do. The first image forming surface serving as the image forming surface of the first spectral α is the same as the original image forming surface of the image forming lens 19, and a color CCD 21 as a first CCCD is provided on the first image forming surface. Have been. Further, the second spectrum β is deflected in a direction orthogonal to the first spectrum α, and the second spectrum β becomes an image plane of the second spectrum β.
A monochrome CCD 22 as a second CCD is provided on the imaging surface. The color CCD 21 is for a low speed and has a low data rate (for example, a maximum of 5).
MHz). Further, the monochrome CCD 22 is for medium speed, and its data rate is set to be sufficiently higher than that of the color CCD 21 (for example, about 20 MHz). Contrary to the embodiment, the monochrome CCD 22 is disposed on the image plane of the first spectral α, and the color CCD 22 is formed on the image plane of the second spectral β.
D21 can also be provided.

As shown in FIG. 1, the case 1 is provided with a mode selection switch 23 as mode selection means which is manually operated. The mode selection switch 23 is used by the operator of the scanner to manually select whether the image to be read (the original G placed on the scanning glass surface 2) is color or monochrome. Even if the original G to be read is a color image, it can be selected as a monochrome image. 1 and 2, K1 is a main substrate, K2 is a color C
A substrate for CD21 and K3 are substrates for monochrome CCD.

FIG. 3 shows an example of a control system, including an image processing device (computer) for performing image processing on a final output from the scanner and an image output device for outputting a processed image. It is. In FIG. 3, a drive circuit of the motor 13 is denoted by reference numeral 31 and two CCs
An output selection circuit for selecting one of the outputs of D21 and D22 is indicated by reference numeral 32. Then, the output selected by the output selection circuit 32 is converted into a digital signal by the A / D converter 33, and is finally output from the scanner.

The drive circuit 31 also has a built-in control circuit for changing the drive speed of the motor 13, and the drive speed of the motor 13, that is, the drive speed of the holder 12 (Which becomes the scanning speed of the CCDs 21 and 22). More specifically, when the color mode of reading a color image is selected by the mode selection switch 23, the motor 13 is driven at a low speed (the scanning speed is low). When the monochrome mode of reading a monochrome image is selected by the mode selection switch 23, the motor 13 is driven at a high speed (the scanning speed is high). As described above, when the color mode is selected, the scanning speed is made slower than when the monochrome mode is selected. The scanning speed at the time of mode selection is set to be about 1/3 of the scanning speed at the time of monochrome mode selection. Of course, the scanning speed when the monochrome mode is selected is set to be the optimum speed for the monochrome CCD 22 used for the medium speed.

The output selection circuit 32 can be configured in the form of a kind of electromagnetic switch. When the color mode is selected, the output from the color CCD 21 is selected and output, and the monochrome mode is selected. At this time, the output from the monochrome CCD 22 is selected and output.

The image processing device 34 can be constituted by, for example, a personal computer, and performs image processing necessary for image compression, image storage, image printing, image communication, and the like. A memory 35 attached to the image processing device 34 temporarily stores a digital signal from the A / D converter 33 for image processing and stores data after image processing. A memory, HDD, or the like is used. The image output device 36 outputs an image that has been subjected to image processing, and includes a display device such as a display, and a printer or the like is used as appropriate.

FIG. 4 is a flowchart showing an example of control in the case where the microcomputer performs the above-described control for changing the scanning speed and the control for selecting the output from the two CCDs. Hereinafter, the flowchart of FIG. 4 will be described. In the following description, S indicates a step. First, S
In 1, it is determined whether or not the color mode is currently selected by checking the operation state of the mode selection switch 23. When the determination in S1 is YES, the control corresponding to the color mode is performed.
In step S3, the driving speed of the motor 13 is set to low speed (scanning speed is low).
Output from is selected. Then, in s4, the selected output is output to the A / D converter 33 as a final output. If the determination in S1 is NO, since the monochrome mode is selected, the driving speed of the motor 13 is first set to high speed (the scanning speed is high) in S5, and then the monochrome CCD 22 is set in S6. Is selected as the final output. After S6, S4
The output from the monochrome CCD 22 is output to the A / D converter 33.

[0021]

According to the present invention, with an inexpensive configuration,
The monochrome image can be read quickly without deteriorating the image quality of both the monochrome image and the color image.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a scanner to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a block diagram showing an example of a control system.

FIG. 4 is a flowchart illustrating a control example of the present invention.

[Description of Signs] 1 Case 2 Glass surface for scanning 11 Guide rod 12 Holder 13 Motor 14 Light source 15-18 Reflection mirror 19 Imaging lens 20 Half mirror 21 Color CCD 22 Monochrome CCD 23 Mode selection switch 31 Drive circuit (motor drive speed) Change) 32 output selection circuit G original

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) MB02 QA10 TA10

Claims (3)

[Claims] 1. An image forming apparatus, comprising: an imaging lens disposed between an imaging lens and an imaging surface of the imaging lens;
A half mirror for splitting the light into two light beams; a color CCD disposed on a first image forming surface serving as an image forming surface for the first light beam; and a second imaging device serving as an image forming surface for the second light beam. A monochrome CCD arranged on the image surface and having a data rate higher than that of the color CCD, and manually selecting a color mode for reading a color image or a monochrome mode for reading a monochrome image Mode selecting means for performing the operation, and the monochrome C when the monochrome mode is selected.
Scanning speed changing means for increasing the scanning speed of the CD from the scanning speed of the color CCD when the color mode is selected; and selecting the mode from the output of the color CCD and the output of the monochrome CCD. Output selection means for selecting and outputting a signal corresponding to the mode selected by the means,
An image reading apparatus comprising: 2. The apparatus according to claim 1, wherein the color CCD and the monochrome CCD are held in the same holder, and scanning is performed by driving the holder in a predetermined scanning direction by driving means. The image reading apparatus according to claim 1, wherein the scanning speed changing unit is set to change a driving speed of the holder by the driving unit. 3. A first step of splitting outgoing light from the imaging lens into two beams, a first beam splitter and a second beam splitter, by a half mirror in front of the image forming plane, and color reading of the image in color. A second step of manually selecting whether the mode is a monochrome mode or a monochrome mode, wherein the color CCD is disposed on the image plane of the first spectrum and the color CCD is disposed on the image plane of the second spectrum and Color CCD
At the same time, scanning is performed simultaneously on both monochrome CCDs having a data rate higher than the data rate of the monochrome mode, and when the monochrome mode is selected, compared to when the color mode is selected. A third step of performing scanning at a high speed, and a fourth step of selecting an output of the CCD corresponding to the mode selected in the third step, out of the output of the color CCD and the output of the monochrome CCD. An image reading method comprising: