JP2002199160A - Color image pickup device and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image pickup device which has expanded receivable wavelength region and has a high sensitivity. SOLUTION: Light from a document 2 which has passed a condenser lens 23 is separated into spectral components of three colors R, G, and B by a diffraction grating 421 of a spectroscopic means 42. Separated spectral components are condensed in specific wavelength regions by a light condensing means 41. A condensed light is received by an R line 51, a G line 52, and B line 53, which are arranged in an imaging device part 50 and are imaging device arrays of colors corresponding to respective wavelength regions. Since the light-condensing means 41 is arranged, wavelength components which have been conventionally discarded can be made incident on respective lines of a line sensor 40. Therefore, the receivable wavelength region is expanded to improve the sensitivity. Light from the document is separated into spectral components by the diffraction grating 421, and they are simultaneously made incident on the R line 51, the G line 52, and the B line 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color image pickup device and an image reading device.

[0002]

2. Description of the Related Art Conventionally, in the case of a line sensor used in an image reading apparatus or the like, a document is read line by line by an image pickup device section in which image pickup devices are arranged in a straight line. Since the image sensor detects the intensity of light incident from the document, it can read only the density of the document. Therefore, when reading a color image, the imaging element unit is set to, for example, 3
It is arranged in a row, and is red (hereinafter, referred to as
R), green (hereinafter, G) or blue (hereinafter, B) light is received. Then, a color image is obtained by combining information corresponding to the received light. As a method of decomposing light from a document into respective components of R, G or B, generally, a method of arranging a color filter on a light receiving surface side of an image sensor unit and receiving light of a different color for each image sensor unit is known. Has been adopted.

On the other hand, in the image pickup device section, it is necessary to arrange an electronic circuit such as a shift register for each column. Therefore, the respective device columns are arranged at a predetermined interval in the sub-scanning direction. As a result, the R element row for receiving R light, the G element row for receiving G light, and the B element row for receiving B light of the color image pickup apparatus can simultaneously read information at different positions on the document. become. Therefore, in order to acquire the information of the light received by each element row as the information of the same position on the document, it is necessary to correct the position of the information output from each element row.

[0004]

Therefore, for example, in the invention disclosed in Japanese Patent Application Laid-Open No. 2-205169, as shown in FIG.
A configuration is known in which light is decomposed using 0, and the decomposed light is incident on three element rows 110, 120, and 130 of the imaging device 100. This makes it possible to simultaneously acquire information on the same position as information on each color. In this case, the separated R,
Since G or B light is incident, a color filter is unnecessary.

[0005] However, as described in Japanese Patent Application Laid-Open No. 2-205169, the following problem arises when light is decomposed using the spectral means 90. Imaging device 10
Since the element rows 110, 120, and 130 of 0 are arranged at a predetermined interval, the element rows 110, 120, and 130 can receive only light in a part of the wavelength region of the split light. That is, since the element rows 110, 120, and 130 are arranged at a predetermined interval from each other, the element row 11
The wavelength range of light that can be received by 0, 120, and 130 is shown in FIG.
As shown in (1), the wavelength is limited to the wavelength corresponding to the width of the light receiving surface of the image sensor. As a result, the element rows 110, 120, and 130 cannot receive a wavelength corresponding to a portion where there is no imaging element.

Therefore, a part of the light incident on the imaging device 100 is discarded, and the incident light cannot be effectively used as information. In addition, since the amount of incident light decreases, the sensitivity of the imaging device 100 decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image pickup device having a high sensitivity in which the wavelength range in which light can be received is expanded. It is another object of the present invention to provide a color imaging device in which manufacturing costs are reduced. Still another object of the present invention is to provide an image reading apparatus that does not require position correction and improves the quality of a read image.

[0008]

According to a first aspect of the present invention, there is provided a color image pickup apparatus including a light condensing means between the spectral means and the image pickup means. The light condensing means condenses light in a predetermined wavelength region out of the light separated by the light separating means and makes the light incident on the imaging means. Thus, the light that is originally discarded can be collected on the imaging unit. In addition, by condensing the light incident on the imaging unit, the wavelength region of the light received by the imaging unit is expanded, and the sensitivity of the imaging unit can be improved. Further, the spectral characteristics can be easily adjusted by adjusting the characteristics of the light collecting means.

According to the color image pickup device of the present invention or the image reading device of the present invention, the image pickup means has three rows of image pickup device sections. A color image can be obtained by setting so that light in different wavelength regions is received for each of the three rows of image sensor units.

According to the color image pickup apparatus of the present invention, the three rows of image pickup device sections of the image pickup means are provided with the first element line and the second element line according to the wavelength region to receive light. It comprises an element row and a third element row. Therefore, light of different colors can be received.

According to the color imaging apparatus of the present invention, the spectral means has a diffraction grating. Since the diffraction grating can be easily formed on the light receiving surface side of the image sensor, the light incident on the image pickup means can be easily separated at low cost.

According to the color image pickup apparatus of the present invention, the spectral means, the light condensing means and the image pickup device are integrally formed. Therefore, for example, a color imaging device can be easily formed by sequentially stacking the transparent member layer, the light condensing unit, the transparent member layer, and the spectral unit when forming the imaging element unit. Therefore, the manufacturing cost of the color imaging device can be reduced.

According to the color imaging apparatus of the present invention, the distance from the first element row to the third element row is the first distance.
The distance is set so as to be smaller than the distance between bright lines of light incident on the element rows. If the distance is larger than the distance between the bright lines of the light incident on the first element row, for example, the third element row may be located at the position of the bright line of the light incident on the first element row. That is, by setting the distance as described above, mixing of lights of different colors is prevented, and sharper light can be read. Note that a bright line in the present specification means a spectrum of light of the same color among spectra generated by interference of light passing through a diffraction grating.

According to the color image pickup apparatus of the present invention, a reflection member is further provided near the third element row. The light incident on the diffraction grating forms a bright line with the optical axis of the incident light as a symmetry axis. Therefore, by disposing the reflecting member, it is possible to make the bright line component generated on the opposite side of the imaging unit with respect to the symmetry axis as the center to the imaging unit. Therefore, the amount of light incident on the imaging means increases,
Sensitivity can be improved.

According to an image reading apparatus according to an eighth aspect of the present invention, there is provided the color image pickup apparatus according to any one of the first to seventh aspects. The color imaging apparatus separates the light from the document by the spectroscopic means, so that it is possible to simultaneously acquire information of each color at the same position on the document. Therefore, position correction becomes unnecessary, and image quality can be improved.

According to the image reading apparatus of the ninth aspect of the present invention, the image reading apparatus includes a prism. Light from the document is split by the prism and is incident on the imaging means. The light condensing means condenses light in a specific wavelength region out of the light split by the prism and makes the light incident on the imaging means. Thus, the light that is originally discarded can be collected on the imaging unit. Also, by collecting the light incident on the imaging means,
The wavelength range of the light received by the imaging unit is expanded, and the sensitivity of the imaging unit can be improved. Further, the spectral characteristics can be easily adjusted by adjusting the characteristics of the light collecting means. In addition, since the imaging unit separates the light from the document using the prism, it is possible to simultaneously acquire information of each color at the same position of the document. Therefore, position correction becomes unnecessary, and image quality can be improved.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 2 shows a flatbed type scanner to which an image reading apparatus according to a first embodiment of the present invention is applied.

As shown in FIG. 2, the scanner 1 has a carriage 20 inside a box-shaped main body. A document table 11 is provided above the main body. Inside the main body, there is provided a carriage 20 that can reciprocate in a sub-scanning direction parallel to the document table 11 by the driving unit 12. The document 2 is placed above the platen 11. Carriage 20
Is mounted with a light source 21, a mirror 22, a condenser lens 23, and a line sensor 40 as a color imaging device. The mirror 22 is provided to reflect the light condensed on the line sensor 40 and increase the optical path length. The condenser lens 23 collects light and makes the light incident on the line sensor 40.

The light source 21 is provided perpendicular to the moving direction of the carriage 20, and a fluorescent lamp or the like is used. Light emitted from the light source 21 is reflected on the surface of the document 2 such as paper, for example, and is incident on the line sensor 40. The processing unit 30 is mounted inside the main body. The processing unit 30
PU (Central Processing Unit) 31, A / D converter 32, RAM (Random Access Memory) 33, ROM
(Read Only Memory) 34 and an image data creation unit 35. The CPU 31 controls the driving unit 12
Controls the movement of the carriage 20, controls the blinking of the light source 21, and controls the entire scanner 1, such as processing of image data created by the image data creation unit 35. The A / D converter 32 converts an analog electric signal output from the line sensor 40 into a digital electric signal. RAM3
Reference numeral 3 temporarily stores digital data created from digital electric signals or image data created by the image data creating unit 35 based on the digital data. The ROM 34 stores a computer program for controlling each unit of the scanner 1 by the CPU 31.

The image data creation section 35 is composed of a shading correction section, a gamma correction section, and other correction sections (not shown). The shading correction unit is A
The digital electric signal output from the / D conversion unit 32 is
Using the correction data obtained by reading a white reference (not shown) before the start of reading, variations in the sensitivity of each element of the line sensor 40 or variations in the light amount of the light source 21 in the main scanning direction are corrected. The gamma correction unit performs gamma correction using a predetermined gamma function, and converts a digital electric signal subjected to shading correction into digital data.
Other correction units perform various conversions such as color correction, edge enhancement, and area enlargement / reduction. Through these processes, a digital electric signal output from the line sensor 40 is created as digital image data. The digital image data created by the image data creation unit 35 is processed by a processing device such as a personal computer (hereinafter referred to as a “personal computer”) 3 externally connected through an interface 13 provided in the main body. Output to

Next, the line sensor 40 will be described in detail. As shown in FIG. 1, the line sensor 40 includes an imaging element unit 50, a light condensing unit 41, and a spectral unit 42. The imaging element units 50 are arranged in three rows according to the wavelength region of the incident light. The imaging element unit 50 has an R line 51 as a first element line, a G line 52 as a second element line, and a B line 53 as a third element line, in order of wavelength from longer to shorter. The R line 51 receives light in a long wavelength region of visible light, that is, red light. The G line 52 receives a region having an intermediate wavelength, that is, green light. The B line 53 receives a region having a short wavelength of visible light, that is, blue light. Each of the lines 51 to 53 of the image sensor unit 50 has a plurality of image sensor rows 511, 521, and 531 in which the image sensors are linearly arranged in the main scanning direction as shown in FIG.

The R line 51, the G line 52 and the B line 53 are respectively arranged at equal intervals. In the case of the present embodiment, the interval between the lines is 8 μm, which is the width of the image sensor row.
They are arranged at intervals of 64 μm larger than m. Further, the distance from the R line 51 to the B line 53 is set to be smaller than the distance between bright lines of red light generated by passing through the diffraction grating 421 of the spectral unit 42. Transfer gates 512, 522, and 53 are provided on the R line 51, the G line 52, and the B line 53, respectively.
2 and shift registers 513, 523, 533 are provided. The electric charge stored in the image pickup device constituting each of the lines 51 to 53 is transferred to the transfer gate 51 at a predetermined timing.
2, 522 and 532, the shift register 513,
523, 533.

The light condensing means 41 is arranged on the light incident side of the image pickup device section 50, that is, on the light emitting side of the spectral means 42. As the light condensing means 41, for example, a trapezoidal rod lens having a parabolic refractive index distribution from the center to the periphery is used. On the light incident side of the light condensing means 41, a light separating means 42 is provided. The diffraction means 4 includes the diffraction grating 4.
21 are formed. The diffraction grating 421 is disposed on the optical axis of light incident from the condenser lens 23 as shown in FIG.

Transparent member layers 43 and 44 made of a transparent material are formed between the image pickup device section 50 and the light collecting means 41 and between the light collecting means 41 and the light separating means 42. As the transparent member layers 43 and 44, for example, resin such as acrylic resin or optical glass is used. Diffraction grating 4
21 is formed, for example, by forming slits at predetermined intervals in a part of the metal film deposited on the surface of the transparent member layer 44. In the case of this embodiment, the interval between the slits is 10 μm.
m.

The line sensor 40 having the above-described configuration includes a transparent member layer 43 and a circuit board 45 on which the image pickup device unit 50 is formed.
The light collecting means 41, the transparent member layer 44, and the vapor deposition film of the light separating means 42 are integrally formed by laminating the deposited films. When stacking the deposition films, a slit is formed and a diffraction grating 421 is formed.

Next, the characteristics of the line sensor 40 will be described. As shown in FIG. 1, light incident on the line sensor 40 from the condenser lens 23 is split by the diffraction grating 421. The split light is decomposed into light of three colors of R, G, and B and emitted from the diffraction grating 421. Light collecting means 41
Collects light emitted from the diffraction grating 421 in a predetermined wavelength region corresponding to light of three colors of R, G, and B. Then, the light condensed by the light condensing means 41 is incident on each of the lines 51 to 53 of the imaging element unit 50 as light condensed in each wavelength region. By arranging the light condensing means 41, light components which are not originally incident on the respective lines 51 to 53 of the imaging element unit 50 are condensed by the light condensing means 41 and incident on the lines 51 to 53 corresponding to the respective colors. .

Next, the operation of the scanner 1 will be described. The user places the original 2 to be read on the original platen 11 and activates, for example, T
A document 2 is sent to the scanner 1 via an application program for controlling the scanner 1 such as WAIN.
To start reading.

When the user issues an instruction to start reading the document 2, the CPU 31 turns on the light source 21. And
The CPU 31 controls the driving unit 12 to move the carriage 20 at a constant speed in the sub-scanning direction. Light from the condenser lens 23 is incident on the line sensor 40, and the incident light is split and condensed as described above, and then is incident on each of the lines 51 to 53 of the imaging element unit 50. R line 5
1, one line of light of the original 2 is simultaneously incident on the G line 52 and the B line 53. Line sensor 4
In the imaging element of 0, incident light is converted into electric charges and accumulated. The accumulated electric charge is stored in the shift register 5 at a fixed timing by a clock signal output every predetermined time.
13, 523, and 533. Shift register 5
13, 523 and 533 are transferred from the line sensor 40 to the A / D converter 32 as analog electric signals.
Output to The output electric signal is output to the A / D converter 3
After being converted into a digital electric signal in step 2, the signal is output to the image data creating unit 35, and image data is created. The digital image data created by the image data creation unit 35 is output to the personal computer 3 via the interface 13. The original 2 is read by repeating the above processing while moving the carriage 20 in the sub-scanning direction at a constant speed.

As described above, the line sensor 40 according to the first embodiment of the present invention has the light condensing means 41 for condensing the split light in a predetermined wavelength region. Therefore, since the light that is originally discarded is received, the wavelength region that can be received by each of the lines 51 to 53 is expanded, and the sensitivity can be improved.

Further, according to the line sensor 40 of the present embodiment, it is possible to easily change the light condensing characteristics of the light condensing means 41 and the slit width of the diffraction grating 421 when the line sensor 40 is manufactured. By adjusting the light collecting characteristics or the slit width, the spectral characteristics of the line sensor 40 can be easily adjusted. Further, the diffraction grating 421 can be formed at the same time when the line sensor 40 is manufactured. Therefore, the spectral characteristics of the line sensor 40 can be easily adjusted, and the diffraction grating 421 can be easily formed, so that the number of manufacturing steps and manufacturing cost of the line sensor 40 can be reduced.

According to the scanner 1 of the present embodiment, the original 2
When reading one line, the light is simultaneously incident on the R line 51, the G line 52, and the B line 53. That is, what is read by the line sensor 40 is always the same position of the document 2. Therefore, for example, it is possible to prevent the deviation of the reading line caused by the vibration of the scanner 1. Therefore, the position correction is unnecessary, and the quality of the read image can be improved.

(Second Embodiment) FIG. 4 shows a scanner according to a second embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description will be omitted. In the line sensor 40 according to the second embodiment, a reflection member 46 is disposed on an end face near the B line 53. Reflective member 46
Reflects light emitted to the reflection member 46 side. The reflection member 46 is formed by depositing, for example, a metal film on the end of the line sensor 40 on the B line 53 side.

As shown in FIG. 6, the light split by the diffraction grating 421 appears as a bright line with its optical axis symmetric with the axis of symmetry. Therefore, by disposing the reflection member 46, it is possible to make a bright line component appearing at a position symmetrical with respect to the position at which the image pickup device unit 50 is disposed across the axis of symmetry enter the image pickup device unit 50. it can. Therefore, in the second embodiment, it is possible to increase the amount of light incident on the imaging element unit 50, and to improve the sensitivity of the line sensor 40.

(Third Embodiment) FIG. 5 shows a scanner according to a third embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description will be omitted. The third embodiment differs from the first embodiment in that a prism 60 is used. The line sensor 70 according to the present embodiment includes an imaging element unit 71 and a light collecting unit 72. A transparent member layer 73 is provided between the imaging element unit 71 and the light collecting unit 72.

The prism 60 is provided at a position distant from the line sensor 70. Light incident on the prism 60 from the condenser lens 23 is split by the prism 60. The split light enters the light condensing means 72 of the line sensor 70, is condensed by the light condensing means 72 as light in a predetermined wavelength region, and is incident on the image sensor 71. In the third embodiment, the incident light can be easily split using the prism 60. Further, since the light separated by the prism 60 is collected by the light collecting means 72, the wavelength component originally discarded can be made incident on the image sensor 71 as in the first embodiment.

As described above, in the embodiments of the present invention, the example in which the line sensor of the present invention is applied to a scanner has been described. However, the present invention is not limited to the scanner, and may be applied to a copying machine.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a line sensor used in a scanner according to a first embodiment of the present invention and light from a document.

FIG. 2 is a schematic block diagram showing a scanner according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a line sensor used in the scanner according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a line sensor used in a scanner according to a second embodiment of the present invention and light from a document.

FIG. 5 is a schematic diagram showing a line sensor used in a scanner according to a third embodiment of the present invention and light from a document.

FIG. 6 is a schematic diagram showing a line sensor used in a conventional scanner and light from a document.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 scanner (image reading device) 2 original document 40 line sensor (color imaging device) 41 condensing unit 42 spectral unit 46 reflecting member 50 imaging element unit 51 R line (first element line) 52 G line (second element line) 53 B line (third element row) 60 prism 70 line sensor (color imaging device) 71 light condensing means 72 imaging element section

Claims (11)

[Claims] 1. A spectroscopic means for decomposing incident light, a condensing means disposed on a light emission side of the spectroscopic means, and condensing light separated by the spectroscopic means in a specific wavelength region; An image pickup device that receives an image of a specific wavelength region condensed by the light condensing unit, converts the light into an electric signal, and outputs the electric signal, wherein the image pickup device is linearly arranged in a main scanning direction; A color imaging device comprising: 2. The color image pickup apparatus according to claim 1, wherein said image pickup means has three rows of image pickup device sections. 3. The three rows of imaging element sections are composed of a first element row, a second element row, and a third element row from a longer wavelength to a shorter wavelength according to a wavelength region of light to be received. The color imaging device according to claim 2, wherein 4. The color image pickup apparatus according to claim 1, wherein said spectral means has a diffraction grating. 5. A transparent member layer made of a transparent material is provided between said light separating means and said light collecting means and between said light collecting means and said image pickup means. The color image pickup apparatus according to claim 4, wherein the light means and the image pickup means are formed integrally. 6. A distance from the first element row to the third element row is set to be smaller than a distance between bright lines of light incident on the first element row. The color imaging device according to claim 4 or 5, wherein 7. The device according to claim 4, further comprising a reflecting member disposed near the third element row.
Or a color imaging device according to 6. 8. A color image pickup apparatus according to claim 1, a light source for irradiating light to a document, and a condenser lens for condensing light from the light source to the color image pickup apparatus. An image reading device comprising: 9. A light source for irradiating a document with light, a condenser lens for condensing light from the light source, and a condenser lens disposed on a light exit side of the condenser lens and condensed by the condenser lens. A prism for dispersing the light, a condensing unit disposed on the light exit side of the prism, and condensing the light disperse by the prism in a specific wavelength region; An image pickup device that receives light of a specific wavelength region condensed by the light condensing unit, converts the light into an electric signal and outputs the electric signal, and the image pickup device is linearly arranged in the main scanning direction. And an image reading device. 10. An image reading apparatus according to claim 9, wherein said image pickup means has three rows of image pickup device sections. 11. The three rows of imaging element units are composed of a first element row, a second element row, and a third element row from a longer wavelength to a shorter wavelength according to a wavelength region of light to be received. The image reading device according to claim 10, wherein