JPH0618808A - Color image reader - Google Patents

Abstract

PURPOSE:To provide a color image reader for reading the color image with high accuracy by plural color light beams by using a color separating means properly set. CONSTITUTION:When a color image illuminated by a light beam from an illuminating means 2 forms the image on a light receiving means 14 arranging plural line sensors RS, BS, GS on the same substrate through a color separating means so as to be read, the color separating means is composed in combination with a wavelength selecting element causing a light beam in the prescribed wavelength range to pass, a polarization element emitting a light beam in a prescribed polarization state and a birefringent element 13 having a different optical action to the light beam in a different polarization state so that the incident light beam is separated into plural color light beams.

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 apparatus, and in particular, it has a plurality of line sensors for color images based on the respective color lights by separating a light flux based on the color image on the original surface into a plurality of color lights. The present invention relates to a color image reading device which is suitable for a color scanner, a color facsimile, etc., which is read by a light receiving means.

[0002]

2. Description of the Related Art Conventionally, color image information on a document surface is imaged on a line sensor (CCD) surface via an optical system, and the output signal from the line sensor at this time is used to generate color image information. Various digital reading devices have been proposed.

For example, FIG. 22 is a schematic view of a main part of an optical system of a conventional color image reading apparatus. In the figure, when the light flux from the color image on the document surface 211 is condensed by the imaging lens 219 and is focused on the line sensor surface described later, the light flux is converted into 3
After being color-separated into three colors of red (R), green (G), and blue (B) through the P prism 220, the light is guided to the surfaces of the respective line sensors 221, 222, and 223. The color images formed on the surfaces of the line sensors 221, 222, and 223 are line-scanned in the sub-scanning direction and read for each color light.

FIG. 23 is a schematic view of a main part of an optical system of a conventional color image reading apparatus. In the figure, when a light flux from a color image on the original surface 211 is condensed by the imaging lens 229 and imaged on a line sensor surface described later, the wavelength selective transmission film having dichroism is added to the light flux. The light beams are separated into three light beams corresponding to three colors via two color separation beam splitters 230 and 231.

Color images based on the three color lights are respectively formed on the surface of a so-called monolithic three-line sensor 232 in which three line sensors are provided on the same substrate surface. As a result, a color image is line-scanned in the sub-scanning direction and read for each color light.

In addition to this, a color image reading means for reading a color image on the original surface by utilizing a color separating means composed of a one-dimensional blazed diffraction grating and a light receiving means provided with three line sensors on the same substrate surface The apparatus is, for example, JP-A-3-179868 or JP-A-3-181269.
It is proposed in Japanese Patent Publication.

[0007]

The color image reading apparatus shown in FIG. 22 requires three independent line sensors, requires high precision, and requires a 3P prism which is difficult to manufacture. The whole becomes complicated and expensive. Furthermore, it is necessary to perform matching adjustment between the image forming light flux and each line sensor independently three times, which causes a problem that assembly adjustment becomes troublesome.

The color image reading apparatus shown in FIG. 23 includes beam splitters 230 and 231.

[0009]

[Outer 1] Now, assuming that the distance between the lines of the line sensor which is preferable in manufacturing is about 0.1 to 0.2 mm, the plate thickness x of the beam splitters 230 and 231 is about 35 to 70 μm.

Generally, it is very difficult to construct a beam splitter having such a thin thickness and maintaining a good optical flatness. When a beam splitter having such a thickness is used, an image is formed on a line sensor surface. There is a problem that the optical performance of a color image is deteriorated.

In a color image reading apparatus using a diffraction grating, the incident angle differs depending on whether the light beam is on-axis or off-axis to the diffraction grating, the diffraction action is different, and the chromaticity changes depending on the angle of view. There has been a problem in that it is necessary to arrange the images with high accuracy corresponding to a color image formed by three colored lights.

The present invention is directed to a wavelength selection element for passing a light beam based on a color image which passes through an image forming optical system and a light beam in a predetermined wavelength range, a polarizing element for emitting a light beam in a predetermined polarization state, and different optics depending on the polarization state. A color image can be read with high accuracy by performing color separation into a plurality of color lights using a color separation means that is an appropriate combination of birefringent elements having an action, and guiding the light onto the corresponding line sensor surfaces. An object is to provide a color image reading device.

[0013]

A color image reading apparatus according to the present invention comprises: (1-a) illuminating a projected object such as a color object or a color image original with light from a black body, and irradiating the projected object from the projected object. In a color image reading apparatus for projecting an image of scattered light onto a solid-state image pickup device such as a CCD by a light projection means to convert an image of the projected object into an electric signal and converting it into image data, a light wave incident on the solid-state image pickup device is converted into a wavelength. It is characterized in that it is decomposed into N (N ≧ 2) by combining each state of polarization direction and position.

(1-a-1) Means for guiding only the states corresponding to the decomposed N light waves or the states contained in each of the N light waves to lead to N or less regions of the solid-state image pickup device To have.

(1-a-2) The means for resolving the polarization direction and position is to decompose the ordinary ray and the extraordinary ray by light wave propagation in the anisotropic crystal.

(1-a-3) The wavelength and polarization direction decomposing means is S-polarized light, P-polarized light depending on the transmission component of the polarization beam splitter.
Separate each color with polarized light.

(1-a-4) The polarization beam splitter is a parallel plate type, and the position of the light beam is displaced by tilting it with respect to the incident light beam.

(1-a-5) The state corresponding to the decomposed N light waves or the state included in each state of the N light waves is selected by a combination of a polarization transmission filter and a wavelength selection filter.

(1-a-6) The solid-state image pickup device is characterized in that a plurality of parallel photoelectric conversion device arrays each having two or more lines are arranged.

(1-b) A color object or a projected object such as a color image original document is illuminated with light by black body radiation, and scattered light from the color object or color image original document is solid-state imaged by a light projecting means such as a CCD. In a color image reading device for projecting an image on a device and converting an image of the projected object into an electric signal to convert it into image data, the solid-state image sensor is a linear CC.
D is arranged in three lines or more, and each linear CCD has a plurality of photoelectric conversion regions (hereinafter referred to as bits) arranged in the line, and the light projecting means is the position of the light flux regulating diaphragm. , The light flux area is divided into two, and one area passes the polarized wave in the direction parallel to or perpendicular to the CCD bit array direction (hereinafter referred to as the sub-scanning direction), which is the solid-state image sensor (right angle to the optical axis). A polarized light transmission filter and a wavelength selection filter that passes the blue wavelength region are provided, and a wavelength selection filter that passes the yellow wavelength region is provided in the other region, and a wavefront propagation distance that passes two regions as necessary. The parallel flat plate glass is arranged so that the (optical path length in terms of air) is equal, and the color object or the image original is in the optical path of the light projecting means or the light projecting means and the solid state. In the optical path of the image pickup device, a parallel plate type tilted with respect to the line array direction (hereinafter referred to as the main scanning direction) of the CCD, which is a solid-state image pickup device, and the optical axis direction in the optical path of the light flux passing through the yellow wavelength selection filter. The polarizing beam splitter is arranged so that the polarizing beam splitter transmits almost 100% of P polarized light and transmits the red wavelength region of S polarized light (in this case, transmits the blue wavelength region). However, the wavelength range of the incident light must be yellow at this time), and the position shift amount of the light flux in the sub-scanning direction by the parallel plate type polarization beam splitter is the solid-state imaging It corresponds to two intervals of the CCD line which is an element, and is of the parallel plate type in the optical path of the light flux passing through the blue wavelength selection filter. A parallel flat plate glass is arranged so as to have a wavefront propagation distance (optical path length equivalent to air) of the light beam splitter, and the color object or color image original and the light projection means and the solid state are in the light path of the light projection means. An anisotropic crystal parallel plate is arranged in the optical path of the image pickup device with a predetermined thickness, and the optical axis of the anisotropic crystal is tilted in the sub-scanning direction with respect to the optical axis of the light projecting means. The angle is about 45 degrees, the cut surface of the anisotropic crystal is almost perpendicular to the optical axis of the light projection means, and the ordinary light flux (ordinary light ray) of the light flux passing through this anisotropic crystal.
And the extraordinary light beam (extraordinary light beam) are separated from each other by a specific line interval of the CCD which is the solid-state image sensor, and the polarization directions of the ordinary light beam and the extraordinary light beam are vertically separated from each other, one of which is the solid-state image sensor. The light beam, which is configured so as to match the line direction of the CCD and is scattered by the above-described configuration in the light beam scattered from the reading line of the color object or the color image original on the incident light beam side when viewed from the CCD which is the solid-state image sensor, C on the passage space incident on each line
Polarization transmission filters capable of passing polarized waves parallel to the CD line direction are alternately arranged. On the surface of the CCD, which is a solid-state image sensor, red, green, blue or blue, green, red are arranged in this order in each line. A combination of a coating filter on the surface of the CCD, which is a solid-state image sensor, and a polarization transmission filter provided on the incident side of the CCD with respect to the incident light flux of the CCD, in which a plurality of light fluxes separated by the above-mentioned configuration are arranged with the wavelength selection coating filter. It is characterized in that there is a one-to-one correspondence with the combination of the polarization state of each of the plurality of light beams and the wavelength region.

(1-B-1) CCD which is a solid-state image pickup device
Is composed of 4 lines, a polarization transmission filter provided at the position of the diaphragm of the light projecting means is not arranged, and the coating filter on the CCD surface has a spectral component of red positive sensitivity in additive color mixing in each line and a spectral component of green. Spectral components, positive transmission of red spectral components of negative sensitivity, order of blue spectral spectral components or vice versa, or in order of exchanging forward transmission of spectral components of red negative spectral components of blue and spectral components of blue The image reading regulation means such as a slit member that regulates the luminous flux of the separated luminous fluxes incident on the CCD is equal to or more than the interval between one adjacent line and less than the interval between three adjacent lines.

(1-b-2) In the image information signal from the solid-state image pickup device such as the CCD of four lines, the positive transmission signal of the spectral spectrum component of red negative sensitivity is compared with other color signals in accordance with the principle of additive color mixing. To subtract.

(1-b-3) The ratio of the luminous flux area division at the diaphragm position of the light projection means is such that the image information signal from the solid-state image pickup device such as CCD is blue when the object to be read or the original is white. The line signal output for red (red spectral component of positive sensitivity) should be set to have almost the same intensity.

(1-b-4) Spectral transmittance distribution of the wavelength selection filter for transmitting in the blue wavelength region arranged at the stop position of the light projecting means and spectrum of the coating filter of the red line on the surface of the CCD which is the solid-state image sensor It is characterized in that there is almost no common transmission wavelength region in the transmittance distribution.

(1-c) A light beam based on a color image proved by the light beam from the illuminating means is made incident on the imaging optical system, and is passed through a color separation means provided on the exit side of the pupil plane of the imaging optical system. When the color image based on each color light is read on the surface of the light receiving means having a plurality of line sensors arranged on the same substrate surface, and the color image based on each color light is read by the light receiving means, The color separation means divides the pupil plane into a plurality of regions by a wavelength selection element provided in the vicinity of the pupil plane of the image forming optical system, and has different wavelengths for the light fluxes incident on the respective divided pupil regions. Light beam having a predetermined color light from each divided pupil region is emitted as a polarized light beam having a predetermined polarization plane by the polarizing element, and the light beam from the polarized light beam is orthogonal to each other by the birefringent element. 2 of the polarization state
One of the two light beams is emitted by displacing the emission position with respect to the other, and a plurality of light beams emitted from different positions of the birefringent element are color-separated into a plurality of color lights through a polarization filter and a color filter. The light is guided to the plurality of line sensors.

(1-d) A plurality of line sensors are made to be the same through color separation means for color-separating the color image illuminated by the light flux from the illumination means into a plurality of color lights by the imaging optical system and emitting the color light. When the color image is read by the light receiving means by forming an image on the surface of the light receiving means arranged on the surface of the substrate, the color separation means has a wavelength selection element for passing a light beam in a predetermined wavelength range and a predetermined polarization state. A polarizing element that emits a light beam,
It is characterized in that an incident light beam is color-separated into a plurality of color lights by combining light beams having different polarization states with birefringent elements having different optical effects.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential portions of a first embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram of a part of FIG. 1.

In the figure, reference numeral 1a denotes a document surface on which a color image 1 is formed. Reference numeral 2 denotes an illuminating means, which radiates a luminous flux (black body radiation) having the spectral characteristic shown in FIG. 3, for example, and illuminates the color image 1.

Reference numeral 3 denotes an infrared cut filter, which has the spectral characteristics shown in FIG. Reference numeral 4 denotes an image forming optical system, which color-separates the color image 1 into predetermined three color lights through respective elements described later, and three line sensors (RS, GS, B).
S) is imaged on the surface of the light receiving means 14 formed on the same substrate surface.

Three line sensors (RS, GS, B
S) is a vertical direction (main scanning direction) on the paper surface as shown in FIG.
Are arranged in parallel with. Reference numeral 9 denotes a light shielding member, which is arranged in the vicinity of the pupil plane of the imaging optical system 4, and divides the pupil plane into two regions 9a and 9b as shown in FIG.

A blue transmission filter 5 and a polarization filter 6 are provided in one area 9a of the pupil plane, and a yellow transmission filter 7 and a transparent plane-parallel plate 8 are provided behind it in the other area 9b. . The blue transmission filter 5 and the yellow transmission filter 7 constitute a wavelength selection element. The blue transmission filter 5 has the spectral characteristics shown in FIG.

FIG. 11 is an explanatory diagram of the spectral characteristics of the light flux passing through the polarization filter 6.

A curve XA in FIG. 11 is the spectral transmittance of the polarized light S having a polarization plane in the line sensor arrangement direction (Z direction, main scanning direction), and a curve XB is a direction orthogonal to the polarized light S (Y direction, sub-scanning direction). ) Is the spectral transmittance of the polarized light P having a polarization plane.

The yellow transmission filter 7 has the spectral characteristics shown in FIG. The plane parallel plate 8 is the blue transmission filter 5
It acts as an optical path length correction filter for aligning the optical path length with the light flux that has passed through the side region 9a.

Reference numeral 10 denotes a parallel plane type polarization beam splitter having the spectral characteristics shown in FIG. In FIG. 7, a curve YS indicates a polarized light S (S which has a polarization plane in the main scanning direction).
The spectral transmittance for polarized light) and the curve YP are the spectral transmittance for polarized light P (P polarized light) having a plane of polarization in the sub-scanning direction. As shown in the figure, all P-polarized light is transmitted, and S-polarized light is transmitted only yellow light.

Reference numeral 11 denotes a dielectric film, which is joined to the polarization beam splitter 10. The polarization filter 6 and the polarization beam splitter 10 form a polarization element. 12
Is a transparent plane-parallel plate, and a polarizing beam splitter 1
It acts as an optical path length correction filter that aligns the optical path length with the light flux passing through the 0-side region 9b.

Reference numeral 13 is a birefringent plate (birefringent element), and the crystal optical axis is inclined by 45 degrees in the sub-scanning direction as shown in FIG. The ordinary ray OL whose polarization direction is the same as the main scanning direction passes through the birefringence plate 13 as it is, and the extraordinary ray EL whose polarization direction is the same as the sub-scanning direction is emitted after being shifted by a predetermined amount in the plane of the paper (sub-scanning direction). . That is, they have different optical effects with respect to light beams having different polarization states.

Reference numeral 15 is a transparent plane-parallel plate, and polarization filters 16, 17 and 18 are provided on the surface thereof. The polarization filters 16, 17, and 18 are set such that the transmittances thereof are, for example, the curve XA in FIG. 11 for the polarized light in the main scanning direction, the sub-scanning direction, and the main scanning direction.

Further, the transmittance is set to, for example, the curve XB in FIG. 11 for the polarized light whose polarization plane is orthogonal to them. Reference numeral 14 denotes a light receiving means, which are transparent plane parallel plates 22 and
It has two line sensors RS, GS, BS and color filters 19, 20, 21.

Three line sensors RS, GS, BS are provided on a part of the transparent plane-parallel plate 22, and a red filter 19, a green filter 20, and a blue as wavelength selection filters are provided on the surface of each line sensor. Filter 2
1 is provided by coating.

FIG. 8 shows the spectral characteristics of the red filter 19, FIG. 9 shows the spectral characteristics of the green filter 20, and the blue filter 21.
The spectral characteristics of the are shown in FIG.

FIG. 14 shows the polarization filter (16, 1) of FIG.
7 and 18) and a color filter (19, 20, 21) are schematic views when viewed from the imaging optical system 4 side. Each element (5, 6, 7, 10, 13, 16, 17, 18, 1) described above
9, 20, 21) constitute one element of the color separation means.

In the present embodiment, the infrared light of the light flux from the color image 1 is cut by the infrared cut filter 3, only visible light (white light, see FIG. 4) passes through and enters the image forming optical system 4. is doing. Of the white light that has entered the imaging optical system 4, the light flux that passes through the blue transmission filter 5 and the polarization beam splitter 6 in the area 9a is blue polarized BLS that oscillates in the direction perpendicular to the blue paper surface (main scanning direction). .

The blue polarized BLS is formed by the plane parallel plate 12
Through the birefringent plate 13 as an ordinary ray, and enters the blue line sensor BS via the polarizing filter 18 and the blue filter 21 that pass only the polarized light in the main scanning direction. The blue image information of the color image 1 is read by the blue line sensor BS.

On the other hand, of the white light incident on the imaging optical system 4, the light flux (green light and red light, see FIG. 6) that has passed through the yellow transmission filter 9 and the plane-parallel plate 8 is not polarized, that is, Exits as a light beam having no light and enters the polarization beam splitter 10 and the dielectric film 11.

Polarizing beam splitter 10 and dielectric film 1
The light flux entering 1 is a red polarization RLS having a polarization plane in the main scanning direction and a yellow polarization YLP having a polarization plane in the sub-scanning direction.
The light is split and emitted into the birefringent plate 13.

Since the polarization beam splitter 10 is tilted in the sub-scanning direction as shown in FIG. 1, the position of the emitted light beam changes. The position change amount at this time is set to match the interval between the two line sensors GS and RS.

The red polarized light RLS passes through the birefringent plate 13 as an ordinary ray as it is, and is incident on the red line sensor RS via a polarizing filter 16 and a red filter 19 which pass only polarized light in the main scanning direction. The red line sensor RS reads the red image information of the color image 1.

The yellow-deflection YLP is emitted from the birefringent plate 13 as an extraordinary ray with its emission position being shifted by a certain amount in the sub-scanning direction and emitted, and passing through only the polarized light in the sub-scanning direction and the green filter 20, It is incident on the green line sensor GS as green polarized light GLP.

At this time, the birefringent plate 1 for the yellow polarized YLP
The shift amount in the sub-scanning direction by 3 is the line sensor RS for red and the line sensor G for green as shown in FIG.
The thickness of the birefringent plate 13 is set so as to be spaced from S. Color image 1 by line sensor GS for green
The image information of the green color is read.

In this embodiment, the red polarized light RLS incident on the red line sensor RS has its polarization plane in the main scanning direction, and the yellow polarized light YLP has its polarization plane in the sub-scanning direction, and the green light is incident on the green line sensor GS. The polarization plane of the polarized light GLP is in the sub-scanning direction, and the polarization plane of the blue polarized light BLS entering the blue line sensor BS is in the main scanning direction.

In this embodiment, the color image 1 on the original surface 1a is color-separated into three color lights by the above-described structure, and the color images are read by the line sensors (RS, GS, BS).

FIG. 15 shows the relative spectral characteristics (R, G, B) of the output signals from the three line sensors (RS, GS, BS) in this embodiment.

In this embodiment, the red polarized light RLS is blocked by the green line sensor GS by the polarizing filter 17, and the blue light line sensor BS is blocked by the blue filter 21 and does not enter either. The blue polarized light BLS is shielded by the polarizing filter 17 for the green line sensor GS, and is shielded by the red filter 19 for the red line sensor RS, and does not enter either. The green polarized light GLP is shielded by the red line sensor RS and the blue line sensor BS by the polarization filters 16 and 18, respectively, and does not enter either.

As described above, in this embodiment, only one color light is made incident on one line sensor, and the other color light which becomes noise light is not made incident so that the reading accuracy of the color image is improved.

Further, three line sensors (RS, GS,
(BS) so that the S / N ratio of the output signal is uniform and the pupil plane of the imaging optical system 4 is made to have a larger blue component than other color components as shown in FIG. 13 (region 5). It is divided.

As described above, in the color image reading apparatus of this embodiment, the aperture area of the lens of the light projecting means is divided into two, the blue wavelength selection filter and the polarization transmission filter are provided on one side, and the yellow wavelength selection filter is provided on the other side. And a parallel plate glass for optical path length correction, a parallel plate for optical path length correction is provided for a blue light beam with respect to a light beam divided into two regions, and a parallel plate type polarization beam splitter is provided in the sub-scanning direction for a yellow light beam. A tilted, S-polarized component is transmitted in the red wavelength region and a P-polarized component is transmitted in yellow as it is. The position shift amount of the light flux by the parallel plate is a monolithic 3-line CCD interval 2 which is a solid-state image sensor. The parallel optical plate of an anisotropic crystal is provided in the optical path of the entire light flux, and the crystal optical axis is inclined in the sub-scanning direction, and the ordinary light flux of light propagation in the crystal, The separation interval of the ordinary light flux is made to correspond to a specific line interval of the CCD, and polarization transmission filters capable of passing a polarized wave parallel to the line direction of the CCD with respect to the light flux incident on each line of the CCD are alternately arranged. R, G, B or B, G, R in each line on the surface
The wavelength selective coating filters are arranged in this order.

As a result, the color information of the same position of the object to be read can be detected by the CCD line solid-state image pickup device of each R, G, B, so that the relative movement of the object to be read and the solid-state image pickup device or the image reading device. Does not adversely affect the consistency of the color separation image data and does not use chromatic dispersion, so the imaging resolution is high, the color reading chromaticity is stable, and the polarization selection filter and wavelength disposed near the CCD Since it is not necessary to limit the luminous flux projected on each line of the CCD in order to select necessary information by the selection filter, it is possible to prevent the positional accuracy of the luminous flux restricting means such as the slit plate and the temporal change and stress change of the member holding it. The conditions are very relaxed, and the apparatus cost can be very low because a reduced projection system can be used. As described above, it is possible to read a high-quality color image with high accuracy, high resolution, and high color reproducibility using a device that is simple and has a low placement accuracy.

FIG. 21 is a schematic view of a main part when the color image reading apparatus of the present invention is applied to a color copying machine. In the figure,
The same elements as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

In this embodiment, the light flux based on the color image 1 placed on the original table glass 50 illuminated by the illumination means 2 is incident on the imaging optical system 4 via the mirrors 51, 52 and 53 and the infrared cut filter 3. is doing. Then, the image forming optical system 4 separates the light into three color lights by using the color separation means including the above-described elements, and forms a color image based on each color light on each line sensor surface of the light receiving means 14. .

The illumination means 2 and the mirrors 51, 52, 5
3 and 3 are moved along the platen glass 50 as indicated by arrows to optically scan the surface of the color image 1 to read the entire surface of the color image 1. The image signal from the light receiving means 14 is processed by the image processing device 54 and digitally output to the storage device 55 or the output device 56.

FIG. 16 is a schematic view of the essential portions of Embodiment 2 of the present invention.
FIG. 17 is an explanatory diagram of a part of FIG. Since the basic configuration of the present embodiment is substantially the same as that of the first embodiment shown in FIG. 1, the points different from the first embodiment will be mainly described.

Color image 10 illuminated by the illumination means 102
The light flux from No. 1 is the slit opening 13 of the slit member 130.
After passing through 0a, infrared light is removed by the infrared cut filter 103 and is incident on the imaging optical system 104. The slit member 130 has three line sensors (RS, GS, B
Unwanted luminous flux is regulated so that the projected luminous flux does not straddle S).

The light beam incident on the image forming optical system 104 is wavelength-selected by the blue wavelength selection filter 105 including the red negative wavelength region (in this embodiment, no polarization filter is used as in the first embodiment), The blue light BL having no bias passes through the plane-parallel plate 112 and is incident on the birefringent plate 113.

The blue light BL passing through the birefringent plate 113 is separated into an ordinary ray and an extraordinary ray depending on the polarization direction, and a blue light including a red negative wavelength region (hereinafter referred to as "extra blue").
Then, the polarization direction is divided into the special blue polarization BBLS having the main scanning direction and the special blue polarization BBLP having the polarization direction having the sub-scanning direction. The polarization direction of the red polarized light RLS is the main scanning direction, and the polarization direction of the yellow polarized light YLP is the sub scanning direction. This is the same as the first embodiment in FIG.

On the plane of the plane-parallel plate 115, polarization filters 116, 1 whose polarization plane passes the polarized light S in the main scanning direction.
18 and polarization filters 117 and 119 that pass the polarized light P whose polarization plane is in the sub-scanning direction.

A line sensor BBP for special blue polarized light BBLP and a special blue polarized light BB are provided on a part of the plane-parallel plate 125.
A line sensor BBS for LS, a line sensor GS for green polarization GLP, and a line sensor RS for red polarization BLS are provided.

A blue filter 124 as a wavelength selection filter is provided on the surface of the line sensor BBP, and a color filter 123 for transmitting a positive wavelength of a red negative component having the spectral characteristic shown in FIG. 18 is provided on the surface of the line sensor BBS. But,
A green filter 121 is provided on the surface of the line sensor GS, and a red filter 120 is provided on the surface of the line sensor RS by coating.

FIG. 19 shows polarization filters (116 to 11).
9) and color filters (120, 121, 123, 12)
4) And each luminous flux (RLS, YLP, BBLS, BBL
FIG. 4 is a schematic view of P) when viewed from the imaging optical system 104 side.

FIG. 20 shows the relative spectral characteristics (R, G, B, BB) of the output signals from the four line sensors (BBP, BBS, GS, RS) in this embodiment.

In the present embodiment, with the above-described structure, the color image 101 is color-separated into color lights by using the additive color mixture method, color determination is performed, and each color is read by each line sensor. We are reading accurate color images.

As described above, in this embodiment, when the scattered light from the object 101 passes through the diaphragm position of the projection lens 104, the blue wavelength selection filter 1 including the red negative wavelength region 1
The wavelength F is selected in 05 (the polarization transmission filter is not used at this time), and the light beam F passing through the birefringent crystal separates the ordinary light beam and the extraordinary light beam according to the polarization direction, and the blue light (hereinafter special A light beam BBLS whose polarization direction is called blue) is in the main scanning direction and a light beam BBLP whose special blue polarization direction is in the sub-scanning direction.

Here, the light beam RLS has a polarization direction in the main scanning direction in the red positive wavelength region, the light beam YLP has a yellow color in the sub-scanning direction, the light beam BBLS has a special blue color in the main scanning direction, and the light beam BBLP. Is a special blue color and the polarization direction is the sub-scanning direction. In the CCD unit 114, the polarization transmission filter 116 that transmits the main scanning direction and the polarization transmission filter 117 and the polarization transmission filter 116 that transmits the sub-scanning direction are the same. Characteristic polarized light transmission filter 1
18 and a polarized light transmission filter 119 having the same characteristics as the polarized light transmission filter 117, a red wavelength transmission filter 120 coated on the photoelectric conversion surface, a green wavelength transmission filter 121, and a red negative component having the spectral transmittance of FIG. A positive wavelength transmission filter 123 and a blue wavelength transmission filter 124 are arranged (the characteristics of the filters 123 and 124 may be exchanged), and the light wave characteristic is selected and read by this combination.

However, since the light beams incident on the green CCD line and the light beams incident on the blue or red negative component CCD line have the same polarization directions and overlap with each other in the wavelength region, as shown in FIG. It is necessary to regulate the luminous flux by means of 16 slit light shielding members 130 so that the projected luminous flux does not extend beyond the CCD 3 lines. Incidentally, the output relative ratio of the CCD is shown in FIG.

As described above, the read color space can be detected in a larger range than that of the conventional one by performing color determination based on the information signal color-separated.

[0076]

According to the present invention, as described above, a wavelength selecting element for passing a light beam based on a color image which passes through the imaging optical system and a light beam in a predetermined wavelength range and a polarized light for emitting a light beam in a predetermined polarization state. Color image by color-separating into a plurality of color lights using color separation means that is an appropriate combination of elements and birefringent elements that have different optical effects depending on the polarization state, and guiding each to the corresponding line sensor surface. It is possible to achieve a color image reading device capable of reading the image with high accuracy.

Particularly, the light wave incident on the solid-state image sensor such as CCD is decomposed into N pieces by the combination of each state of wavelength, polarization direction and position, and the state corresponding to the decomposed light wave is passed through to obtain N of the solid-state image sensor. By guiding to individual areas, color images can be read without depending on the relative movement of the object and the image sensor or the reading device, and the resolution is high, the chromaticity accuracy is good, and the physical accuracy of the device configuration is not severe and high quality. A color image reading device capable of reading various color images is achieved.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a part of FIG.

FIG. 3 is an explanatory diagram of spectral characteristics of a light beam from the illumination unit of FIG.

4 is an explanatory diagram of spectral characteristics of the infrared cut filter of FIG.

5 is an explanatory diagram of spectral characteristics of the blue transmission filter of FIG.

FIG. 6 is an explanatory diagram of spectral characteristics of the yellow transmission filter of FIG.

7 is an explanatory diagram of spectral characteristics of the polarization beam splitter in FIG.

FIG. 8 is an explanatory diagram of spectral characteristics of the red filter of FIG.

9 is an explanatory diagram of the spectral characteristics of the green filter of FIG.

FIG. 10 is an explanatory diagram of spectral characteristics of the blue filter of FIG.

11 is an explanatory diagram of spectral characteristics of the polarization filter of FIG.

12 is an explanatory view of the birefringent plate of FIG.

13 is an explanatory diagram of the vicinity of the pupil of the imaging optical system in FIG.

FIG. 14 is an explanatory diagram of a part of FIG.

FIG. 15 is a relative diagram of each line output of the 3-line CCD of the first embodiment.

FIG. 16 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 17 is an explanatory diagram of a part of FIG.

18 is an explanatory diagram of spectral characteristics of the color filter of FIG.

FIG. 19 is an explanatory diagram of a part of FIG.

FIG. 20 is a relative diagram of each line output of the 4-line CCD of the second embodiment.

FIG. 21 is a schematic view of an embodiment when the present invention is applied to a color copying machine (color scanner).

FIG. 22 is a schematic view of a main part of a conventional color image reading device.

FIG. 23 is a schematic view of a main part of a conventional color image reading device.

[Explanation of symbols]

 1 Color image 2 Illumination means 3 Infrared cut filter 4 Imaging optical system 5 Blue transmission filter 6,16,17,18 Polarization filter 7 Yellow transmission filter 8,12 Parallel plane plate 9 Light shielding member 10 Polarization beam splitter 11 Dielectric film 13 birefringent plate 14 light receiving means 19 red filter 20 green filter 21 blue filter BS blue line sensor GS green line sensor RS red line sensor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The alignment direction (Z-direction, the main scanning direction) curve XA is a line sensor of FIG. 11 min light transmittance that having a plane of polarization, the curve XB direction perpendicular to the polarization S is (Y-direction, the sub scanning direction ) to a partial light transmittance that having a polarization plane.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Reference numeral 10 denotes a parallel plane type polarization beam splitter having the spectral characteristics shown in FIG. In FIG. 7, a curve YS indicates a polarized light S (S which has a polarization plane in the main scanning direction).
The spectral transmittance for polarized light) and the curve YP are the spectral transmittance for polarized light P (P polarized light) having a plane of polarization in the sub-scanning direction. As shown in the figure, all P-polarized light is transmitted and S-polarized light is red.
And transmits only color light.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 16

[Correction method] Change

[Correction content]

FIG. 16

Claims (14)

[Claims] 1. A color object or a projected object such as a color image original document is illuminated with light by black body radiation, and scattered light from the projected object is projected and imaged on a solid-state imaging device such as a CCD by a light projecting means. In a color image reading device for converting an image of the projected object into an electric signal and converting it into image data, N (N ≧ 2) light waves incident on the solid-state imaging device are combined in each state of wavelength, polarization direction and position. A color image reading device characterized by being decomposed into. 2. A means for allowing only a state corresponding to the decomposed N light waves or a state included in each state of the N light waves to pass and leading to N or less regions of the solid-state imaging device. The color image reading device according to claim 1. 3. The color image reading apparatus according to claim 1, wherein the means for resolving the polarization direction and the position is decomposed into ordinary rays and extraordinary rays by light wave propagation in the anisotropic crystal. 4. The color image reading apparatus according to claim 1, wherein the wavelength and polarization direction separating means separates the S-polarized light and the P-polarized light into individual colors according to the transmission components of the polarization beam splitter. 5. The color image reading apparatus according to claim 4, wherein the polarization beam splitter is a parallel plate type, and the position of the light beam is displaced by tilting it with respect to the incident light beam. 6. The selection of a state corresponding to the decomposed N light waves or a state included in each state of the N light waves is performed by a combination of a polarization transmission filter and a wavelength selection filter. Color image reading device. 7. The color image reading apparatus according to claim 2, wherein the solid-state image pickup device is an array of a plurality of parallel photoelectric conversion device arrays each having two or more lines. 8. A color object or a projected object such as a color image original document is illuminated with light by black body radiation, and scattered light from the color object or color image original document is projected onto a solid-state imaging device such as a CCD by a light projecting means. In a color image reading apparatus which forms an image of the projected object and converts it into an electric signal to convert it into image data, in the solid-state image pickup device, linear CCDs are arranged in three lines or more, and each linear CCD is A plurality of photoelectric conversion regions (hereinafter referred to as "bits") are arranged in the line, and the light projecting means divides the light flux region into two at the position of the diaphragm for regulating the light flux, and one region is a solid-state image sensor. And a polarization transmission filter that allows polarized waves to pass in a direction parallel to or perpendicular to the CCD bit array direction (hereinafter referred to as the sub-scanning direction), which is also perpendicular to the optical axis.
A wavelength selection filter that passes the blue wavelength region is provided, and a wavelength selection filter that passes the yellow wavelength region is provided in the other region, and a wavefront propagation distance (air-equivalent optical path length) that passes two regions as necessary. ) Are arranged parallel to each other, and pass through the yellow wavelength selection filter in the optical path of the color object or image original and the light projection means or in the optical path of the light projection means and the solid-state image sensor. A parallel plate type polarization beam splitter inclined with respect to the line array direction (hereinafter referred to as the main scanning direction) of the CCD, which is a solid-state image sensor, and the optical axis direction is arranged in the optical path of the light beam to be transmitted.
Almost 100% of the polarized light is transmitted and S-polarized light is transmitted in the red wavelength region (in this case, it may be transmitted in the blue wavelength region. The wavelength region must be yellow), and the position shift amount of the light flux in the sub-scanning direction by the parallel plate type polarization beam splitter corresponds to two line intervals of the CCD which is a solid-state image sensor. The parallel plate glass is arranged in the optical path of the light flux passing through the blue wavelength selection filter to be equal to the wavefront propagation distance of the parallel plate type polarization beam splitter (optical path length in air), A parallel plate of anisotropic crystals having a predetermined thickness is provided in the light path of the color object or color image original and the light projection means or in the light path of the light projection means and the solid-state imaging device. Is, the optical axis of the anisotropic crystal is inclined in the sub-scanning direction with respect to the optical axis of said light projecting means,
The tilt angle is about 45 degrees, the cut surface of the anisotropic crystal is almost perpendicular to the optical axis of the light projection means, and the ordinary light beam (ordinary ray) of the light beam passing through this anisotropic crystal is The separation interval of the extraordinary light beam (extraordinary light beam) corresponds to a specific line interval of the CCD which is the solid-state image sensor, and the polarization directions of the ordinary light beam and the extraordinary light beam are vertically separated from each other, one of which is the solid-state image sensor. Of the CCD, which is configured to match the line direction of the solid-state image sensor, and is separated by the above-described configuration in the light scattered from the reading line of the color object or the color image original on the incident light flux side when viewed from the CCD which is the solid-state image sensor. CCs, which are solid-state image pickup devices, are arranged by alternately arranging polarization transmission filters capable of passing polarization waves parallel to the direction perpendicular to the CCD line direction in a passage space incident on a line.
On the surface of D, red, green, blue or blue in each line,
The wavelength selective coating filters are arranged in the order of green and red, and the plurality of luminous fluxes separated by the above-mentioned structure are coated with the CC on the CCD surface which is a solid-state image sensor and the CC.
A color image reading apparatus characterized in that a combination of polarization transmission filters provided on the incident side of the CCD with respect to the incident light flux of D corresponds to the combination of the polarization state and the wavelength region of each of the plurality of light fluxes in a one-to-one correspondence. 9. A CCD which is a solid-state image pickup device is composed of four lines, a polarization transmission filter provided at the position of the diaphragm of the light projecting means is not arranged, and the coating filter on the CCD surface is red in the additive color mixture in each line. Positive sensitivity spectral component, green spectral component, red negative sensitive spectral component, positive transmission, blue spectral component order or vice versa, or red negative sensitive spectral component An image of a slit member or the like that is arranged in an order in which the order of the blue spectral components is exchanged, and each separated light flux incident on the CCD regulates the light flux at a distance between one adjacent line and less than three adjacent line intervals. 9. The color image reading apparatus according to claim 8, further comprising a reading control unit. 10. In the image information signal from the solid-state image pickup device such as a CCD of 4 lines, the positive transmission signal of the spectral spectrum component of red negative sensitivity is subtracted from other color signals according to the principle of additive color mixing. The color image reading device according to claim 9. 11. The ratio of the luminous flux area division at the diaphragm position of the light projecting means is such that the image information signal from the solid-state image pickup device such as CCD indicates that the object to be read or the document is white and red (red positive). 9. The color image reading apparatus according to claim 8, wherein the line signal outputs of the spectral spectrum component of sensitivity are set to have substantially the same intensity. 12. The spectral transmittance distribution of a wavelength selection filter for transmitting in the blue wavelength region, which is arranged at the stop position of the light projecting means, and the spectral transmittance distribution of a coating filter of a red line on the surface of CCD, which is a solid-state image sensor, are common. 9. The color image reading apparatus according to claim 8, wherein the transmission wavelength region of the color image reading apparatus does not substantially exist. 13. A light flux based on a color image illuminated by a light flux from an illumination means is made incident on an imaging optical system, and a plurality of color separation means are provided on an exit side of a pupil plane of the imaging optical system. When a color image based on each color light is read and a color image based on each color light is read on the surface of the light receiving means where a plurality of line sensors are arranged on the same substrate surface and the light receiving means reads the color image based on each color light The means divides the pupil plane into a plurality of regions by a wavelength selection element provided in the vicinity of the pupil plane of the imaging optical system, and produces light fluxes of different wavelength ranges with respect to the incident light fluxes to the respective divided pupil regions. A light beam having a predetermined color light from each of the divided pupil regions is passed through and emitted as a polarized light beam having a predetermined polarization plane by a polarizing element, and the light beam from the polarized light beam is polarized by a birefringent element in mutually orthogonal polarization states. One of the two light beams to the other On the other hand, the emission position is displaced and emitted, and a plurality of light beams emitted from different positions of the birefringent element are color-separated into a plurality of color lights through a polarization filter and a color filter, and are guided to the plurality of line sensors. A color image reading device characterized by being illuminated. 14. A plurality of line sensors are provided on the same substrate surface via a color separation unit that color-separates an incident light beam into a plurality of color lights by an imaging optical system to illuminate a color image illuminated by the light beams from the illumination unit. When the color image is read by the light receiving means, an image is formed on the surface of the light receiving means arranged at, and the color separation means emits a light beam of a predetermined polarization state and a wavelength selection element that passes a light beam of a predetermined wavelength range. A color image reading apparatus, characterized in that an incident light beam is color-separated into a plurality of color lights by combining a polarizing element for controlling the light beam and a birefringent element having a different optical action with respect to light beams having different polarization states.