JPH06121117A - Color image sensor - Google Patents

Abstract

PURPOSE:To irradiate an original with illumination light in three colors at the same angle. CONSTITUTION:Illumination light emitted from three fluorescent tubes 21a, 21b and 21c is transmitted through respectively faced dye optical filters 28a, 28b and 28c and turned into the illumination light in three primary colors required for reading color image. Each of the illumination light is totally reflected on the surface of a transparent wall inside and an optical guide 27, and the advancing direction is arranged. An original 23 placed on an original stage 22 is irradiated with the illumination light at the same angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image sensor for converting and inputting, for example, text or image color manuscript information into a series of electric signals, and particularly to a color manuscript connected to an information device such as a workstation. It is suitable for a color image scanner for reading the.

[0002]

2. Description of the Related Art Generally, a color image sensor irradiates light emitted from individual three primary color light sources onto a document in a time-division manner, and forms a light-dark distribution image of the document for each light on a photoelectric conversion element. , Is used in an image scanner of the type for converting this image into an electric signal.

As shown in FIG. 13, the conventional color image sensor has a light emitting portion having a length adapted to the maximum width of the read original 1 as a light source of three primary color illumination lights of red, green and blue for illuminating the read original 1. Three cylindrical fluorescent tubes 2R,
It is equipped with 2G and 2B.

The fluorescent tubes 2R, 2G and 2B are used for reading a reflection type original, and the original stage 3 is made of transparent glass.
When the transparent original is read at the position shown by the solid line in FIG. 13 on the back side of FIG. 13, the transparent original is set at the position shown by the dotted line in FIG. 13 above the read original 1 placed in close contact with the original stage 3. There is.

Optical filters 4R, 4G, and 4B having a characteristic of transmitting light in the red, green, and blue wavelength bands are attached to the sides of the fluorescent tubes 2R, 2G, and 2B facing the read original.

A black light-shielding tape 5 is attached to the surface of the fluorescent tubes 2R, 2G, 2B other than the light extraction direction where the optical filters 4R, 4G, 4B are attached. This prevents light that does not pass through 4G and 4B from being emitted to the outside.

The three fluorescent tubes 2R, 2G, 2B and the optical filters 4R, 4G, 4B are placed in close contact with the three primary color lights emitted from the fluorescent tubes 2R, 2G, 2B on the original stage 3. It is installed so that a predetermined amount of light can be obtained in each of the linear reading areas of the read document 1.

Irradiation lights emitted from the fluorescent tubes 2R, 2G and 2B have emission wavelengths shown by solid lines in FIG. 2, respectively, and the optical filters 4R, 4G and 4B are shown in FIG.
Has a wavelength transmission characteristic that transmits light in the red, green, and blue wavelength bands indicated by the two-dot chain line.

Therefore, the light emitted from the fluorescent tubes 2R, 2G, and 2B corresponds to the optical filters 4R and 4 respectively.
By transmitting G and 4B, illumination light of the three primary colors necessary for reading a color image image having wavelength characteristics as shown in FIG. 3 in the visible light wavelength region can be obtained.

The grayscale image of the line area of the read original 1 illuminated by the illumination light of the three primary colors is the original image mirror 6
After passing through the visible light transmitting optical filter 7 through a to 6c, an image is formed on the line photoelectric conversion element 9 such as the line CCD by the image forming lens set 8. The visible light transmission optical filter 7 has the wavelength transmission characteristics shown by the dotted line in FIG. 2, and reduces the incidence of light other than visible light on the photoelectric conversion element 9.

The three fluorescent tubes 2R, 2G and 2B are
The high-frequency lighting circuit repeats the lighting in sequence and the lighting is switched at high speed at the timing shown in FIG. 4, and the photoelectric conversion element 9 synchronizes with the lighting of each light source, and the grayscale image of the line area of the original 1 in the three primary color illumination. Import data.

The original stage 3 on which the original 1 is placed is scanned in the scanning direction (X direction in FIG. 13) at a constant speed slower than the lighting period of the fluorescent tubes 2R, 2G and 2B.
Then, the two-dimensional original is read by repeatedly inputting the grayscale image of the line area to the photoelectric conversion element 9.

[0013]

In the conventional color image sensor, the irradiation angles of the illumination light of three colors with which the read original 1 is irradiated are different. Therefore, as shown in FIG. 14, if there is a portion of the original 1 on the original stage 3 that does not come into close contact with the original stage 3 due to a fold or a stitch, when the original 1 is read, at the portion that does not come into close contact with the original stage 3. There is a drawback in that the irradiation positions of the three colors of illumination light are displaced, the preset light amount balance for each illumination light is lost in the line area to be read, and the input image is misregistered.

In view of the above, the present invention provides a color image sensor for illuminating a document with illumination light of three colors at the same angle.

[0015]

According to a first aspect of the present invention, a document is irradiated with light emitted from individual three primary color light sources, and an image of the document in a region irradiated with light is formed on a photoelectric conversion element. The color image sensor for forming an image is provided with a light guide means for guiding the respective lights emitted from the three primary color light sources to a predetermined area of the document surface at the same angle.

According to a second aspect of the present invention, the light guide means is provided with a light guide made of a translucent medium that guides each light emitted from the three primary color light sources to the light emission surface.

According to a third aspect of the present invention, the light guide means is provided with an optical filter having a characteristic of transmitting, absorbing or reflecting light in a specific wavelength band.

According to a fourth aspect of the invention, an optical filter having a characteristic of transmitting, absorbing or reflecting light in a specific wavelength band is provided on the light incident surface or the light emitting surface of the light guide.

According to a fifth aspect of the present invention, a part or the whole of the light guide is formed of a material having a property of absorbing light in a specific wavelength range.

According to a sixth aspect of the present invention, there is provided a means for solving the problems, wherein the surface of the light guide is provided with a reflecting mirror for reflecting the light inside the light guide toward the light exit surface.

In the means for solving the problem according to claim 7, a part of the surface of the light guide is a condenser for directing the light emitted from the light emitting surface.

The means for solving the problem according to the eighth aspect is such that an optical filter having different transmittance depending on the light transmitting position is provided on the light incident surface or the light emitting surface of the light guide.

According to a ninth aspect of the invention, the light guide is resin-molded using a light-transmissive resin as a material.

[0024]

In the above means for solving the problems, when the light guide is used as the light guide, the respective irradiation lights emitted from the individual light sources enter the inside of the light guide formed of the translucent medium. At this time, the wavelength band of each irradiation light is selected by various optical filters provided in the light guide, and the red,
The illumination light is suitable for reading a color image image having emission wavelength characteristics of green and blue.

This illumination light is confined inside the guide by being reflected by the transparent wall surface of the light guide or a reflecting mirror provided on the light guide, and propagates inside the light guide to be aligned in the traveling direction. The directivity of each illumination light is enhanced by the condenser, and the illumination light is emitted from the emission surface at the same angle to efficiently illuminate the document.

As described above, the light confining effect in the light guide suppresses the diffusion of the illumination light and improves the light utilization efficiency in the predetermined illumination area.

Further, a structure in which an optical filter, a reflecting mirror and a light collector are integrally provided in the light guide, or the light guide itself is formed of a light-transmitting material having an optical filter effect improves the light utilization efficiency. It is possible to integrally form the member for performing the light guide, and to simplify the manufacturing process and make the quality uniform.

When a light guide is not used for the light guiding means, an optical filter having wavelength dependence of transmittance (reflectance) and an optical filter having reflection or transmission characteristics in a region corresponding to a specific emission wavelength are used. In combination, the irradiation light emitted from each individual light source is transmitted or reflected to match the traveling direction of the light and select the emission wavelength.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIG. 1 is a block diagram of a color image sensor of a first embodiment of the present invention, FIG. 2 is a diagram showing the spectral characteristics of three primary color fluorescent tubes and dye optical filters, and FIG.
Is a diagram showing wavelength characteristics of three primary color illumination light, and FIG. 4 is a lighting timing chart of three fluorescent tubes.

The color image sensor of the first embodiment, as shown in FIG. 1, emits light emitted from three cylindrical fluorescent tubes 21a, 21b, 21c which are the light sources of the three primary color illumination lights of red, green and blue. An illumination optical system A for irradiating a document 23 placed on the document stage 22 and a line photoelectric for inputting a grayscale image (document image) generated by irradiating the line regions of the document 23 with an electric signal. And a reading optical system B for forming an image on a conversion element 25 (for example, a line CCD).

The illumination optical system A includes the fluorescent tubes 21a,
21b and 21c, and a light guide means 24 for guiding the respective lights emitted from the fluorescent tubes 21a, 21b and 21c to the original 23 at the same angle.

The above three fluorescent tubes 21a, 21b, 21c
Are arranged below the document stage 22 in parallel,
It has a diameter of 10 mm and a length (A3 size compatible: 340 mm) adapted to the maximum width of the read document 1. Further, these three fluorescent tubes 21a, 21b, 21c are shown in FIG.
As shown by the solid lines in (a), (b) and (c), those having emission wavelength characteristics having emission wavelength peaks in the red, green and blue wavelength bands are used.

The light guide means 24 comprises three fluorescent tubes 21.
a light guide 27 that aligns the irradiation light from a, 21b, and 21c in the traveling direction, and transmits light in the red, green, and blue wavelength bands that are arranged on the respective light incident surfaces 27a, 27b, and 27c of the light guide 27. Dye optical filter 28a, 28
b and 28c, and an ND optical filter 29 arranged on the light emitting surface 27d of the light guide 27 and having a different transmittance depending on the light transmission position.

The light guide 27 is formed by injection molding using a transparent acrylic resin (refractive index: 1.49), and one guide is branched into three, and three fluorescent tubes 21a. , 21b, 21c, and three light incident surfaces 27a, 27b, 27c, respectively, and one light emitting surface 27d from which the light is emitted from the light incident surfaces 27a, 27b, 27c. .

The dye optical filters 28a, 28b, 2
8c has the transmission characteristics shown by the chain double-dashed lines in (a), (b), and (c) of FIG. 2, respectively. The optical filter 28a having a red transmission characteristic is formed by printing a pigment ink containing a pigment on the light incident surface 27a of the light guide 27 facing the fluorescent tube 21a. Also, the optical filters 28b and 28c having the transmission characteristics of green and blue are provided.
Is formed by multi-layer vapor deposition of a dielectric thin film on the light incident surfaces 27b and 27c of the light guide 27 facing the fluorescent tubes 21b and 21c.

The ND optical filter 29 is used for the light guide 2
7 is integrally printed on the light emitting surface 27d, and the light transmittance of the central portion in the longitudinal direction is made lower than the light transmittance of the end portion so that the illuminance of the central portion of the line area of the document 23 is darker than the end portion. It is set to illuminate.

The light incident surfaces 27a, 2a of the light guide 27 are
7b and 27c and the various light filters on the light exit surface 27d are orthodox by attaching these optical filters 28a, 28b and 28c individually formed on a glass substrate to a predetermined portion of the light guide 27. Any method may be used.

In addition, the light emitting surface 27d of the light guide 27 has N
Instead of the structure in which the D optical filter 29 is arranged, the light incident surface 2
7a, 27b, 27c, each dye optical filter 28a, 2c
8b and 28c may have a structure in which the transmittance correction function of the ND optical filter 29 is added. Three fluorescent tubes 21a, 21
b, 21c and the light guide 27 are housed in a light-shielding case 30 except for the light emitting surface 27d of the light guide 27, and the light not entering the light guide 27 from the three fluorescent tubes 21a, 21b, 21c. Prevents leakage.

The reading optical system B includes three reflecting mirrors 31 for reflecting the original image in the linear area of the original 23.
a, 31b, 31c and the reflection mirrors 31a, 31b,
The image forming lens set 32 forms a document image passing through 31c on the line CCD 25 in a reduced form by about 1/5.

The image forming lens set 32 is provided with a visible light transmitting optical filter 33 having a spectral transmission characteristic shown by a dotted line in FIG. Spectral transmission characteristics of the visible light transmitting optical filter 33 and the fluorescent tubes 21a, 21b,
21c Emission wavelength characteristics and optical filters 28a, 28
Together with the transmission characteristics of b and 28c, it is possible to illuminate light of the three primary colors having the wavelengths shown in FIG. 3, and the illumination light obtains a document image necessary for reading a color image image.

Further, the brightness of the original image formed on the line CCD 25 by the imaging lens set 32 generally becomes uneven as the peripheral portion farther from the optical axis becomes darker. However, before the document image reaches the image forming lens set 32, the irradiation light passes through the ND optical filter 29, so that the central portion of the document image is darker than the end portions. Therefore, when the original image passes through the image forming lens set 32, the brightness becomes uniform, and the nonuniformity of the brightness due to the lens characteristics can be optically corrected.

In the above structure, three fluorescent tubes 21a,
21b and 21c are sequentially turned on by the high-frequency lighting circuit at the timing shown in FIG.

These three fluorescent tubes 21a, 21b, 21c
The irradiation light emitted from each of the dye optical filters 28a, 28b, and 28c, which are opposed to each other, transmits
Only the red, green, and blue wavelength bands are transmitted, and the illumination light of the three primary colors necessary for reading a color image image is obtained.

This illuminating light is made incident inside from the respective light incident surfaces 27a, 27b, 27c of the light guide 27,
Of these, the critical angle (42.1
Light incident at an incident angle of 6 deg) or more is guided by the light guide 2
7 is totally reflected by the transparent wall surface of the light guide 27 due to the difference in refractive index between 7 and the outside air, and is confined inside the light guide 27.

The illumination light of each color inside the light guide 27 is adjusted in its traveling direction by repeating total reflection on the wall surface of the light guide 27, and then the light emitting surface 2 of the light guide 27.
After passing through 7d, the linear area of the read document 23 placed on the document stage 22 is irradiated at substantially the same angle.

The original image of the line area of the read original 23 illuminated by the illumination light of the three primary colors is relayed from the reflection mirror 31a directly under the original stage 22 to the mirror 31b and then to the mirror 31c, and the visible light transmitting optical filter 33 is passed through. After passing through, the image is formed on the line CCD 25 by the imaging lens set 32 in a reduced size of about 1/5.

At this time, the original stage 22 is mounted on the fluorescent tube 2
It moves in the scanning direction (X direction in FIG. 1) at a constant speed that is sufficiently slow compared to the lighting cycle of 1a, 21b, and 21c. Therefore, on the line CCD 25, the original image of the linearly cut area illuminated by the illumination light of the three primary colors is repeatedly formed.

The line CCD 25 includes the fluorescent tubes 21a and 2a.
The original images irradiated with the three primary color illumination lights are read in synchronization with the lighting of 1b and 21c, and the original images are converted into a series of time-series electric signals. The two-dimensional original is read based on this electric signal.

In this way, the read original 23 on which the three primary color illumination lights of red, green and blue are placed on the original stage 22.
The original image can be read by irradiating the same at the same angle. Therefore, even if there is a portion of the document 23 that does not come into close contact with the document stage 22 due to a fold or a stitch, the irradiation positions of the illumination lights on the surface of the document 23 are the same, and the light amount balance is not lost, and the read image is not affected. It is possible to prevent the occurrence of color misregistration. In addition, the light confinement effect in the light guide 27 suppresses the diffusion of the illumination light and improves the light utilization efficiency in the predetermined illumination area of the document 23.

Further, the optical filters 28a, 28b, 2
By integrally providing the 8c and the ND optical filter 29 to the light guide 27, it is possible to simplify the assembling process that involves alignment of the individual optical elements.

<Second Embodiment> FIG. 5 is a block diagram of the color image sensor of the second embodiment, and FIG. 6 is a diagram showing the spectral characteristics of the interference film optical filter. The members having the same functions as those in the first embodiment are designated by the same reference numerals.

The color image sensor of the second embodiment comprises an illumination optical system C and a reading optical system D as shown in FIG. Then, in the illumination optical system C, the respective lights emitted from the fluorescent tubes 21a, 21b, and 21c similar to those in the first embodiment are placed on the manuscript stage 22 at the same angle on the manuscript 23.
The light guide means 40 for guiding to.

The light guide means 40 is arranged below the original stage 22 and has three light guides 42 for aligning the light emitted from the three fluorescent tubes 21a, 21b, 21c in the traveling direction.
43 and 44, and two types of interference film optical filters 45 and 46 which are arranged in the light guides 42 and 43 and which transmit or reflect the irradiation light from the three fluorescent tubes 21a, 21b and 21c according to their wavelength bands. A reflecting mirror 47 that reflects the irradiation light in the light guide 44 toward the original stage 22 and a condenser 48 that condenses the irradiation light reflected by the reflecting mirror 47.

As shown in FIG. 5, the light guide 42 has an arc-shaped mounting surface 42 whose upper surface is along the fluorescent tube 21a for red light.
a and the inclined surface 42 of ± 45 degrees with the lower surface protruding downward
b and 42c. The light guide 43 is the light guide 4.
2 has the same shape, and its upper surface is the inclined surface 42 of the light guide 42.
The inclined surfaces 43b and 43c are arranged so as to face the b and 42c, and the lower surface is an arc-shaped mounting surface 43a along the green fluorescent tube 21b.

The fluorescent tube 21c for blue color is arranged between the inclined surface 42c of the light guide 42 and the inclined surface 43c of the light guide 43 in the vicinity of the inclined surfaces 42c and 43c.

The light guide 44 has an inclined surface 44a that is in complete contact with the inclined surface 42b of the light guide 42 and an inclined surface 44b that is in close contact with the inclined surface 43b of the light guide 43. It is arranged in parallel with 22.

The interference film optical filter 45 includes an inclined surface 42b of the light guide 42 and an inclined surface 43c of the light guide 43.
Is formed integrally by multi-layer vapor deposition of dielectric thin film on
It has the spectral transmission (reflection) characteristics shown in FIG. 6A for incident light of 5 degrees. In addition, the interference film optical filter 46
Are integrally formed on the inclined surface 42c of the light guide 42 and the inclined surface 43b of the light guide 43 by multilayer vapor deposition of dielectric thin films, and the spectral transmission shown in FIG. It has a (reflection) characteristic. In addition, in FIG. 6, the solid line (T) represents the transmittance and the broken line (r) represents the reflectance.

The reflecting mirror 47 is formed by depositing a metal film on the inclined surface 44c of the light guide 44 opposite to the inclined surfaces 44a and 44b. This reflector 47
An illuminance correction function similar to that of the ND optical filter 29 of the first embodiment is added, and the central portion and the end portion of the light guide 44 are adjusted to have different reflectances in the longitudinal direction.

The condensing body 48 is a condensing lens in which a part of the upper surface of the light guide 44 above the reflecting mirror 47 is formed in a cylindrical lens shape, and the irradiation light from the reflecting mirror 47 is orthogonal to the original illumination area. The light is condensed in the direction (X-X 'direction in FIG. 5) to enhance the directivity of the irradiation light. Further, on the surface of the condenser lens 48, a visible light transmission optical filter 49 having the same spectral transmission characteristics (see (c) of FIG. 6) as the visible light transmission optical filter of the first embodiment is integrally formed by printing. It is located in.

Further, three fluorescent tubes 21a, 21b, 21
c, the inclined surface 4 of the light guides 42, 43 and the light guide 44
The vicinity of 4a and 44b is housed in a light shielding case 50 to prevent leakage of irradiation light that does not enter the light guides 42, 43 and 44.

The reading optical system D has a structure in which the visible light transmitting optical filter 33 is removed from the reading optical system B of the first embodiment, and the original image in the line-shaped area of the original 23 is drawn by the line C.
It is formed so as to form a reduced image on the CD 25. In addition,
Other configurations are the same as those in the first embodiment.

In the above structure, three fluorescent tubes 21a,
21b and 21c are sequentially turned on by the high frequency lighting circuit. Most of the irradiation light emitted from the red fluorescent tube 21a is incident on the light guide 42, and the interference film optical filters 45 and 46 on the inclined surfaces 42b and 42c thereof.
To reach.

Most of the irradiation light that has hit the optical filter 45 on the inclined surface 42b is transmitted according to the spectral characteristics of the optical filter 45, and reaches the optical filter 46 on the inclined surface 43b of the light guide 43. Here, most of the light is reflected toward the light guide 44 according to the spectral characteristics of the optical filter 46.

On the other hand, most of the irradiation light striking the optical filter 46 on the inclined surface 42c is reflected according to the spectral characteristics of the optical filter 46, and the optical filter 4 on the inclined surface 42b is reflected.
Reach 5. Here, according to the spectral characteristics of the optical filter 45, most of the light passes through the optical filter 45 and enters the light guide 44.

Most of the irradiation light emitted from the green fluorescent tube 21b is incident on the light guide 43, and the inclined surface 43 thereof.
The optical filters 45 and 46 of b and 43c are reached.

Most of the irradiation light that has hit the optical filter 46 on the inclined surface 43b is transmitted according to the spectral characteristics of the optical filter 46, and reaches the optical filter 45 on the inclined surface 42b of the light guide 42. Here, most of the light is reflected in the direction of the light guide 44 according to the spectral characteristics of the optical filter 45.

On the other hand, most of the irradiation light striking the optical filter 45 on the inclined surface 43c is reflected according to the spectral characteristics of the optical filter 45 and reaches the optical filter 46.
Here, most of the light passes through the optical filter 46 according to the spectral characteristics of the optical filter 46 and enters the light guide 44.

Most of the irradiation light emitted from the blue fluorescent tube 21b is the optical filters 45, 4 on the inclined surface 42c of the light guide 42 and the inclined surface 43c of the light guide 43.
Reach 6. Most of the irradiation light that has hit both optical filters 45 and 46 passes through both filters 45 and 46 according to the spectral characteristics of the optical filters 45 and 46, and the light guide 4
After passing through 2 and 43, the light passes through the optical filters 45 and 46 again and enters the light guide 44.

In this way, each fluorescent tube 21a, 21b, 21
Each of the irradiation lights emitted from c is reflected by the optical filter 4
5, 46 is transmitted or reflected by the light guide 44.
In addition, the emission reflection characteristics are selected in the required three primary color wavelength range (see FIG. 3) to become the three primary color illumination light.

The three primary color illumination lights that have entered the light guide 44 are trapped inside the light guide 44 and aligned in the traveling direction by repeating total reflection on the transparent wall surface of the light guide 44. Thereafter, the illumination light is adjusted by the reflecting mirror 47 so that the illuminance is different between the central portion and the end portion, and is reflected in the direction of the original stage 22. The reflected illumination light is reflected by the visible light transmitting optical filter 49 of the condenser lens 48.
Thus, only the visible light is transmitted, and the light is condensed by the condenser lens 48 to enhance the directivity, and the linear region of the document 23 placed on the document stage 22 is efficiently illuminated.

The original image of the line area of the read original 23 illuminated by the illumination light of the three primary colors is reflected by the reflecting mirror 3.
1a, 31b, 31c and the imaging lens set 32, and a reduced image is formed on the CCD 25.
The two-dimensional original is read in addition to the sub-scan in the direction.

In this way, the read original 23 on which the three primary color illumination lights of red, green and blue are placed on the original stage 22.
The original image can be read by irradiating the same at the same angle. Therefore, as in the first embodiment, it is possible to prevent color misregistration from occurring in the read image.

Further, the light guides 42, 4 for aligning the irradiation directions of the light emitted from the fluorescent tubes 21a, 21b, 21c.
The three, 44, and the condenser lens 48 for increasing the directivity of the light can efficiently irradiate the predetermined areas of the manuscript 23 with the three primary color illumination lights.

Further, the interference film optical filters 45 and 46 are used as the light guides 42 and 43, and the reflecting mirror 4 having an illuminance correction function.
7 and a condensing lens 48 formed with an optical filter 49
Is integrally provided with the light guide 44, it is possible to simplify an assembling process involving alignment of the individual optical elements.

<Third Embodiment> FIG. 7 is a block diagram of the illumination optical system of the third embodiment, and FIG. 8 is a diagram showing the spectral characteristics of the interference film optical filter and the visible light transmitting optical filter. The members having the same functions as those in the first and second embodiments are designated by the same reference numerals.

The color image sensor of the third embodiment comprises a light guiding means 60 in which the structure of the light guiding means 40 of the illumination optical system C of the second embodiment is arranged.

As shown in FIG. 7, the light guide means 60 is arranged below the original stage 22 and has three fluorescent tubes 21a, 21.
three light guides 61, 62, 63 for aligning the irradiation light from b, 21c in the traveling direction, and the light guides 61, 62, 6
The interference film optical filters 64 and 65 and the dye optical filter 66, which are arranged in No. 3 and transmit or reflect the irradiation light from the three fluorescent tubes 21a, 21b, and 21c according to their wavelength bands, and the irradiation formed on the light guide 61. It is composed of a condensing body (condensing lens) 67 for condensing light.

On the upper surface of the light guide 61, a condenser lens 67 similar to the condenser lens of the second embodiment having an illuminance correction function is integrally formed, and the side surface in the longitudinal direction is blue fluorescent light. An arc-shaped mounting surface 61a is formed along the tube 21c, and a lower surface is a filter surface 61b in which an interference film optical filter 64 is formed by multi-layer vapor deposition of dielectric thin films. It has a slope.

The light guide 62 has an inclined surface 62 whose upper surface is in complete contact with the filter surface 61b of the light guide 61.
a, the side surface in the longitudinal direction is a circular arc-shaped mounting surface 62b along the green fluorescent tube 21b, and the lower surface is a filter surface 62c formed by the interference film optical filter 65 by multilayer vapor deposition of dielectric thin films. , And has an inclination of 45 degrees with respect to the green fluorescent tube 21b.

The light guide 63 has an inclined surface 63 whose upper surface is completely in close contact with the filter surface 62c of the light guide 62.
a, and the lower surface is an arc-shaped mounting surface 63b on which the dye filter 66 is printed and which follows the red fluorescent tube 21a.

The interference film optical filters 64 and 65 and the dye optical filter 66 are respectively shown in FIG.
It has the spectral characteristics of (b) and (c). Note that FIG. 8D shows the optical filter 4 printed on the condenser lens 67.
9 shows the transmission characteristics, and other configurations are similar to those of the second embodiment.

In the above structure, three fluorescent tubes 21a,
The irradiation light emitted from 21b and 21c is the spectral characteristics of the interference film optical filters 64 and 65 and the dye optical filter 6.
6 is transmitted or reflected in accordance with the wavelength transmission characteristic, is matched with the traveling direction, and its emission wavelength characteristic is selected as the wavelength band of the three primary color illumination light (spectral characteristic of FIG. 3).

Then, only the visible light is transmitted through the visible light transmitting optical filter 49 of the condenser lens 67, and the condenser lens 6
The light is condensed by 7 to increase the directivity, and the original stage 22
The linear area of the original document 23 placed on is efficiently illuminated. After that, the two-dimensional original is read in the same manner as in the second embodiment, and the same effect as in the second embodiment can be obtained.

<Fourth Embodiment> FIG. 9 is a block diagram of the color image sensor of the fourth embodiment. The members having the same functions as those in the first embodiment are designated by the same reference numerals.

The color image sensor of the fourth embodiment comprises an illumination optical system E and a reading optical system B as shown in FIG. Then, in the illumination optical system E, the respective lights emitted from the fluorescent tubes 21a, 21b, and 21c similar to those in the first embodiment are placed on the manuscript stage 22 at the same angle and placed on the manuscript 23.
It is provided with a light guide means 70 that guides the light to illuminate.

The light guiding means 70 is the interference film optical filter 45 of the second embodiment arranged below the original stage 22.
Interference film optical filters 71, 7 having the same characteristics as 46
2 and a condensing body 73 that condenses the irradiation light from the three fluorescent tubes 21a, 21b, 21c transmitted or reflected by the interference film optical filters 71, 72.

Two interference film optical filters 71 are arranged parallel to the original stage 22 in the scanning direction (XX 'direction in FIG. 9), and the interference film optical filters 72 are arranged on the two optical filters 71. Two pieces are arranged vertically so that they are orthogonal to each other. The interference film optical filters 71 and 72 have a cross shape,
Partition parts 74a, 74b, 74c, 7 divided into four
4d is formed.

The partition parts 74a, 74b, 74c, 7
In the partition portion 74a in the X'direction of FIG. 9 on the lower side of 4d, the fluorescent tube 21a for red is provided with the interference film optical filter 71,
The fluorescent tube 21c for blue is also attached to the partition 74b in the X direction of FIG. 9 on the lower side, and the fluorescent tube for green is attached to the partition 74c in the upper X direction. 21b is also attached.

The partition 7 in the X'direction of FIG. 9 on the upper side
4d, the condensing body 73 is the interference film optical filter 71,
It is arranged at an angle of 45 degrees with respect to 72. The light collector 73 is a cylindrical lens having an illuminance correction function.

The three fluorescent tubes 21a, 21b, 21
The surface of the c that does not face the interference film optical filters 71 and 72 is shielded by a black tape 75 having a light shielding property, and the light whose direction and wavelength band are not adjusted by the filters 71 and 72 is on the surface of the document 23. It reduces the amount of light emitted to the.

In the above structure, three fluorescent tubes 21a,
Irradiation lights emitted from 21b and 21c are transmitted or reflected according to the spectral characteristics of the interference film optical filters 71 and 72, their traveling directions are aligned in the direction of arrow W in FIG. 9, and their spectral characteristics are the three primary color illumination light. To a predetermined wavelength band (spectral characteristic of FIG. 3).

The respective illumination lights aligned in the direction of the arrow W are condensed by the cylindrical lens 73 in the direction orthogonal to the original illumination area (the XX 'direction in FIG. 9), and the directivity is enhanced, so that the original is illuminated. The linear area of the document 23 placed on the stage 22 is efficiently illuminated. After that, the two-dimensional original is read in the same manner as in the first embodiment.

As described above, it is possible to prevent the occurrence of color shift in the read image as in the first embodiment, and to condense and direct the light emitted from the fluorescent tubes 21a, 21b and 21c by the cylindrical lens 73. To improve the quality of the original 2
It is possible to efficiently irradiate a predetermined region of No.

<Fifth Embodiment> FIG. 10 is a block diagram of the illumination optical system of the fifth embodiment. The members having the same functions as those in the first embodiment are designated by the same reference numerals.

The color image sensor of the fifth embodiment comprises a light guide means 80 in which the structure of the light guide means 70 of the illumination optical system E of the fourth embodiment is arranged.

The light guiding means 80, as shown in FIG. 10, has an interference film optical filter 81, which has the same characteristics as the interference film optical filter of the third embodiment arranged below the original stage 22.
82 and the dye optical filter 83, and the three fluorescent tubes 21a, 21b and 21 transmitted or reflected by the interference film optical filters 81 and 82 and the dye optical filter 83.
and a condenser 86 that condenses the irradiation light from c.

The interference film optical filters 81 and 82 are 45 for the green and blue fluorescent tubes 21b and 21c.
It is arranged with an angle of degrees. Dye optical filter 83
Are arranged close to the light emitting direction side of the red fluorescent tube 21a.

The three fluorescent tubes 21a, 21b, 21
The surface of the c that does not face the interference film optical filters 81 and 82 is shielded by a black tape 84 having a light-shielding property, and the fluorescent tubes 21b and 21c on both sides of the green and blue fluorescent tubes 21b and 21c are shielded. Three light-shielding plates 85 are arranged so as to be parallel to 21c. This is the filter 81,8
The light whose direction and wavelength band are not adjusted by 2 and 83 is reduced from irradiating the surface of the document 23.
The other configurations are the same as those in the fourth embodiment.

In the above structure, three fluorescent tubes 21a,
Irradiation light emitted from 21b and 21c is the spectral characteristics of the interference film optical filters 81 and 82 and the dye optical filter 8.
1 is transmitted or reflected according to the wavelength transmission characteristics of FIG.
The traveling direction is aligned with the direction of the arrow W of 0, and its spectral characteristic is selected to a predetermined wavelength band (spectral characteristic of FIG. 3) of the three primary color illumination light.

The respective illumination lights aligned in the direction of the arrow W are condensed by the cylindrical lens 86 in the direction orthogonal to the original illumination area (the XX 'direction in FIG. 10) to increase the directivity, and The linear area of the document 23 placed on the stage 22 is efficiently illuminated. After that, the two-dimensional original is read in the same manner as in the first embodiment, and the same effect as in the fourth embodiment can be obtained.

Further, the light emitted from the fluorescent tubes 21a, 21b, 21c is condensed by the cylindrical lens 86 to enhance the directivity, and the three primary color illumination lights can be efficiently applied to a predetermined area of the original 23. .

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in the first to fifth embodiments,
When reading a transmissive original placed on the original stage 22, the illumination optical systems A, C, and E may be installed above the original stage 22 shown by the dotted lines in FIGS.

In the first embodiment, an optical filter having the same spectral transmission characteristics as the visible light transmitting optical filter 33 is used instead of the structure in which the visible light transmitting optical filter 33 is arranged integrally with the imaging lens set 32. A structure integrally formed by printing by superimposing on the ND optical filter 29 on the light emitting surface 27d of the light guide 27, or the light guide 2
The structure 7 may be formed of a resin material having the spectral transmission characteristics of the visible light transmission optical filter 33.

In the second embodiment, instead of the visible light transmitting optical filter 49 having the spectral transmission characteristic arranged on the surface of the condenser lens 48, the light guide 44 itself has the same spectral transmission as the visible light transmitting optical filter 49. A structure formed of a material having characteristics may be used.

In the first to fifth embodiments, the wavelength band of the three primary color illumination lights necessary for reading the color image image obtained by the combination of each light source and each optical filter is limited to the wavelength band shown in FIG. For example, as shown in (a) of FIG. 11, when there is some radiation intensity in the infrared band, or as shown in (b) when the band of each color is narrow, the original to be read is You may change within the range which can reproduce color.

Further, each light source and each optical filter for obtaining illumination light of the three primary colors are not limited to the wavelength characteristics (see FIGS. 2, 6 and 8) and configurations shown in each embodiment. For example, in place of the red fluorescent tube 21a used in each of the embodiments, red light emission (for example, the emission wavelength 66 is shown on the printed wiring board 90 as shown in FIG.
An LED line light source unit 92 having a structure in which chip diode lamps 91 of 0 nm) are mounted in an array may be used as a red light source.

In this case, the dye optical filter which transmits the three primary colors red used in each embodiment can be omitted. Similarly, green and blue fluorescent tubes 21
Instead of b and 21c, LED line light source units using green and blue light emitting diodes may be used, respectively, and the optical filters for transmitting green and blue may be omitted. As described above, even if the characteristics and configurations of the light source and the optical filter are changed, the structure may be such that the illumination light of the above three primary colors can be obtained as a result.

Furthermore, in the first to fifth embodiments,
The three primary color light sources may move with respect to the stationary original 23. Alternatively, the original 23 may be read for each light source of each color without irradiating the three primary color light sources in a time division manner to read the original 23.

[0110]

As is apparent from the above description, according to the present invention 1, 2, 3 and 4, the irradiation light emitted from the individual three primary color light sources has the three primary colors necessary for reading a color image image by various optical filters. The original is illuminated at the same angle as illumination light. Therefore, even if there are folds or bindings in the document, the irradiation position of each illumination light on the surface of the document will be the same, the light amount balance will not be lost, and color shift in the read image can be prevented. it can.

According to the fourth, fifth and sixth aspects, the respective illumination lights are aligned in the traveling direction by the light guide and the reflecting mirror and are confined in the light guide. This confinement effect suppresses the diffusion of illumination light and improves the light utilization efficiency in a predetermined illumination area.

According to claim 7, each illumination light is
Since the directivity is enhanced by the light collector, it is possible to efficiently irradiate a predetermined area of the document.

Further, according to claims 4 to 9, various optical filters, a condenser, and a reflecting mirror are integrally provided on the light guide having a light-transmitting property, and the light guide is formed of resin, whereby individual optical There is an excellent effect that the assembling process involving the alignment of the elements can be simplified.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color image sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing spectral characteristics of three primary color fluorescent tubes and dye optical filters.

FIG. 3 is a diagram showing wavelength characteristics of three primary color illumination lights.

FIG. 4 is a lighting timing chart of three fluorescent tubes.

FIG. 5 is a configuration diagram of a color image sensor of a second embodiment.

FIG. 6 is a diagram showing spectral characteristics of an interference film optical filter.

FIG. 7 is a configuration diagram of an illumination optical system according to a third embodiment.

FIG. 8 is a diagram showing spectral characteristics of an interference film optical filter and a visible light transmitting optical filter.

FIG. 9 is a configuration diagram of a color image sensor according to a fourth embodiment.

FIG. 10 is a configuration diagram of an illumination optical system according to a fifth embodiment.

FIG. 11 is a diagram showing wavelength characteristics of other three primary color illumination lights.

FIG. 12 is a perspective view of a line light source unit using a light emitting diode.

FIG. 13 is a configuration diagram of a conventional color image sensor.

FIG. 14 is a diagram showing a state in which a conventional color image sensor irradiates an original that is not in close contact with the original stage.

[Explanation of symbols]

 21a, 21b, 21c Three primary color light source 23 Original 24, 40, 60, 70, 80 Light guide 25 Photoelectric conversion element 27, 42, 43, 44 61, 62, 63 Light guide 28a, 28b, 28c 66,83 Dye optical filter 33,49 Visible light transmission optical filter 45,46,64,65 71,72,81,82 Optical filter 27a, 27b, 27c Light incident surface 27d Light emission surface 47 Reflector 48,67 Condenser lens 73,86 Cylind Kullens

Claims (9)

[Claims] 1. A color image sensor for irradiating a document with light emitted from individual three primary color light sources, and forming an image of the original document in a region irradiated with the light on a photoelectric conversion element. 2. A color image sensor comprising: a light guide unit that guides the light of FIG. 2. The color image sensor according to claim 1, wherein the light guide means is provided with a light guide made of a translucent medium that guides the lights emitted from the three primary color light sources to one light emitting surface. And color image sensor. 3. The color image sensor according to claim 1, wherein the light guide means includes an optical filter having a characteristic of transmitting, absorbing or reflecting light in a specific wavelength band. 4. The color image sensor according to claim 2, wherein at least one surface of the light incident surface and the light emitting surface of the light guide has a characteristic of transmitting, absorbing or reflecting light in a specific wavelength band. A color image sensor comprising an optical filter having the same. 5. The color image sensor according to claim 2, wherein a part or the whole of the light guide is made of a material having a property of absorbing light in a specific wavelength range. 6. The color image sensor according to claim 2, wherein at least a part of the surface of the light guide is provided with a reflecting mirror for reflecting the light inside the light guide toward the light emission surface. Image sensor. 7. The color image sensor according to claim 2, wherein a part of the surface of the light guide is a condenser for directing the light emitted from the light emitting surface. 8. The color image sensor according to claim 2, wherein an optical filter having different transmittance depending on a light transmitting position is provided on at least one surface of the light incident surface and the light emitting surface of the light guide. A color image sensor characterized in that 9. The color image sensor according to claim 2, wherein the light guide is resin-molded with a light-transmissive resin as a material.