JPH06237338A - Picture reading optical device - Google Patents

Abstract

PURPOSE:To obtain an excellent picture by making a flaw or a dust or the like unremarkable on an original itself or a glass plate or the like supporting the original in the subscanning direction in the picture read optical device integrated with a picture reader. CONSTITUTION:A luminous quantity of a read light (L1,L2) orthogonal to a filter 16 is attenuated by transmitting the light through a 1st print pattern 24 or a 2nd print pattern 25 made of light diminishing materials arranged in the main scanning direction at a prescribed width and at a prescribed interval. On the other hand, the luminous quantity of a read light (L3,L4) with an inclination with respect to the main scanning direction (direction shown in the arrow X) of the filter 16 by a prescribed angle (e) is made incident into an original 14 without being attenuated. Thus, the visual recognition of a flaw in the subscanning direction of the original 14 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading optical device which irradiates a document on which image information is recorded with reading light and reads the transmitted light or reflected light by a line sensor.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus for photoelectrically reading image information recorded on a document such as a film with a line sensor, performing desired image processing on the image information, and producing a film original plate for printing and plate making has been known. Widely used.

In the image reading apparatus, when the transmitted light or reflected light from the original is introduced into each pixel of the line sensor to obtain an electric signal corresponding to the image information, the read light is incident on a portion other than the pixel. In order to prevent the generated flare, for example, a slit member is provided between the light source and the original, and the light irradiation area of the light source is formed in a slit shape in the width direction of the line sensor.

[0004]

However, the reading light that has passed through the gap between the slit members has a narrow numerical aperture in the sub-scanning direction because its emission direction is narrowed down within a predetermined range. The effect of unevenness existing in the upper sub-scanning direction is likely to appear. As a result, scratches and the like are reproduced in the main scanning direction.

Therefore, the applicant of the present invention has proposed an image reading optical device capable of preventing reproduction of scratches, dust, unevenness, etc. existing on the original document or the glass plate holding the original document. (See Japanese Patent Application No. 4-55357). In this Japanese Patent Application No. 4-55357, a long cylindrical lens is disposed between the slit member and the original in the main scanning direction, and the reading light is made divergent to reduce the visual recognition of scratches and the like. A filter for controlling the light amount distribution of the reading light is further arranged between the light source and the document so that a predetermined range around the optical axis of the reading light incident on the document has a predetermined dimming characteristic. By setting
It discloses a technical idea for further reducing the visibility of scratches and the like in the main scanning direction.

The present invention has been made in connection with the above proposal, and is capable of obtaining a good image by making scratches, dust, and the like due to the original document itself or a glass plate holding the original document inconspicuous. An object is to provide an optical device.

[0007]

In order to achieve the above-mentioned object, the present invention irradiates a document with reading light and receives transmitted light or reflected light of the document with a line sensor to obtain desired image information. In the image reading optical apparatus for obtaining the above, a filter for controlling the light amount distribution of the reading light is arranged between the light source for irradiating the reading light and the document on which the image information is recorded, and the filter has a constant width and a constant width. A first dimming element arranged in the longitudinal direction of the line sensor at a predetermined interval
And a predetermined width from the first dimming portion and a predetermined distance from the first dimming portion,
It is characterized by comprising a second dimming portion having a predetermined dimming characteristic and arranged in the longitudinal direction of the line sensor at regular intervals.

Further, according to the present invention, a light source for irradiating the reading light to the document on which the image information is recorded, a first light collecting means for collecting the reading light in the sub-scanning direction, and the first light collecting means. Second light collecting means for collecting the reading light in the sub-scanning direction on the original with the light collecting position of the reading light as the front focal point, a light source for irradiating the reading light, and recording of image information. A filter which is disposed between the read original and a light amount distribution of the read light, a line sensor which receives the read light from the original and converts the read light into an electric signal in the main scanning direction, and A third light condensing unit which is arranged between the document and the line sensor and condenses the reading light from the document on the line sensor, and the filter is constant in the sub-scanning direction. It has a fixed width and is arranged in the main scanning direction at a fixed width and at regular intervals. A first dimming portion having a predetermined dimming characteristic, a predetermined distance from the first dimming portion, and a constant width and a constant distance between the first dimming portion. And a second dimming portion having a predetermined dimming characteristic arranged in the main scanning direction.

[0009]

In the image reading optical device according to the present invention described above, the reading light emitted from the light source and vertically incident on the filter is
The amount of light is attenuated by being transmitted through the first dimming portion or the second dimming portion having a predetermined dimming characteristic, and the light is incident on the document. On the other hand, the reading light that is incident on the filter at an angle of a predetermined angle is incident on the document through the gap between the first dimming portion and the second dimming portion, so the amount of the reading light may be attenuated. Absent. Therefore, when there is a scratch in the sub-scanning direction of an original or the like, the total amount of light transmitted through the original can be made constant regardless of whether or not the reading light is refracted by the original, so that an image that is less affected by the scratch Can be obtained.

Further, in the image reading optical apparatus according to the present invention, the reading light from the light source is condensed by the first condensing means to the front focus of the second condensing means, and then the light quantity at a predetermined angle is obtained by the filter. The distribution is controlled, and the light is condensed on the document by the second light collecting means. The reading light from the document is further condensed on the line sensor by the third condensing means,
It is converted into an electric signal.

In this case, the filter has a constant width in the sub-scanning direction, and a first dimming characteristic which has a predetermined width and is arranged in the main scanning direction at constant intervals. Since it includes the light portion, the second dimming portion, and the transmitting portion other than the first and second dimming portions, the light amount control is performed in both the main scanning direction and the sub scanning direction. Therefore, even if there are scratches or the like in the main scanning direction and the sub-scanning direction of the document, it is possible to prevent the reduction of the total light amount, and as a result, it is possible to obtain an image in which the scratches and the like are inconspicuous.

[0012]

The preferred embodiments of the image reading optical apparatus according to the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing the principle of the image reading optical device 10 of this embodiment. The image reading optical device 10 is arranged between a light source 12 that emits diffused reading light, a document 14 on which image information is recorded, and the light source 12 and the document 14, and is arranged in the main scanning direction (arrow). A filter 16 formed to be long in the X direction), a reading lens 18 for condensing the reading light transmitted through the filter 16, and the reading lens 1
And a line sensor 20 that receives the light condensed by 8 and converts it into an electric signal.

The filter 16 is made of a light-transmissive member 22 having a flat shape and a predetermined thickness (A), for example, transparent glass. On the upper surface of the light transmissive member 22, a first print pattern 24 made of a plurality of light attenuating members, for example, chrome (Cr) is vapor-deposited at regular intervals (B) in the main scanning direction. . The first print pattern 24 is formed with a width (C) substantially the same as the space (B) between the first print patterns, and its transmittance is set to about 50%. On the other hand, on the lower surface of the light transmissive member 22, a second print pattern 25 composed of a plurality of light attenuating members is vapor-deposited on the upper surface at a position corresponding to a gap between the first print patterns 24.

The image reading optical device 10 according to the present embodiment is
It is basically configured as described above, and its operation and effect will be described next.

The reading light emitted from the light source 12 is guided to the filter 16, the reading light transmitted through the filter 16 is applied to the original 14, and the reading light transmitted through the original 14 and carrying image information is read by the reading lens. The line sensor 20 collects the condensed light, and the line sensor 20 receives the condensed light to convert it into an electric signal to obtain desired image information.

Here, the relationship between the amount of light at an arbitrary point P on the original 14 and the incident angle θ of the reading light is that the transmittance of the filter 16 is 50% when the incident angle θ = 0 ° (the reading light L1, L
2) 25% with respect to the incident angle θ at which the first print pattern 24 and the second print pattern 25 overlap (reading light L
3), 100% for other incident angles θ (reading light L
4) and the shading by the incident angle θ, the result is as shown in FIG.

That is, as shown in FIGS. 3A and 3D, for example, when the incident angle θ of the reading lights L5 and L6 with respect to the filter 16 is 0 °, either reading light L5 or L6 is detected.
The transmittance at any scanning position of is also 50%. Further, as shown in FIGS. 3C and 3F, the incident angle is
For example, in the reading light with θ ₁ = arctan (B / A), the transmittance of the reading lights L7 and L8 passing through both the first print pattern 24 and the second print pattern 25 is 25%, and Read light L9, L that does not pass through either
The transmittance of 10 is 100%. In this case, the average transmittance of the reading lights L7 to L10 when the incident angle is θ ₁ is 6
It becomes 2.5%. Furthermore, the incident angle θ of the reading light is 0 <θ <
In the case of θ ₁ , as shown in FIGS. 3B and 3E, the transmittance of the reading light L11 passing through both the first print pattern 24 and the second print pattern 25 is 25%, and only the second print pattern 25 is transmitted. The transmittance of the reading light L12 is 50%, and the transmittance of the reading light L13 that does not pass through both print patterns is 100%.

As described above, different incident angles (0 to 0) are used.
Based on the transmittance distribution obtained for θ ₁ ) and the luminance characteristics of a normal diffused light source in which the amount of light decreases as the incident angle θ increases, as shown in FIG. It is possible to derive a characteristic curve of the irradiation angle and the light amount. The characteristic curve shown in FIG. 2 is determined by the thickness (A) of the light transmissive member 22, the widths (C) of the first and second print patterns 24 and 25, and the intervals (B) thereof.

Therefore, assuming that the numerical aperture of the reading lens 18 is NA (NA∝sin α), when the original 14 is not scratched, the reading light in the range A1 is read by the line sensor 20 as shown in FIGS. 2 and 5A. Be led to. On the other hand, scratches 2 on the original 14
When there is 6, the optical path changes due to the refraction at the scratched portion 26, so that as shown in FIG.
The reading light of A3 and A3 is guided to the line sensor 20. In this case, from the characteristics of FIG. 2, it is possible to guide the same amount of light to the document 14 in the case of FIG. 5A and the case of FIG. 5B. As a result, the read light that is less affected by the scratches 26 arrives without reducing the total amount of light received by the line sensor 20,
This makes it possible to obtain a good image. In the case where the filter 16 according to the present embodiment is not used, as shown in FIG. 4, the brightness characteristic decreases in the amount of light as the irradiation angle θ increases. When the change occurs, the amount of light received by the sensor 20 decreases, and a black scratch image is generated.

Next, FIG. 6 shows an image reading optical device 30 in which the filter 16 is incorporated in a Koehler illumination optical system.

The image reading optical device 30 includes a light source 32 formed of a fluorescent tube and having an aperture 31, and the light source 32.
A cylindrical lens (first condensing means) 34 disposed below the cylindrical lens 34, a field stop 38 having a slit 36 disposed below the cylindrical lens 34, and a field stop 38 disposed below the field stop 38, A filter 16 having first and second print patterns 24, 25 arranged at a predetermined width (C) and a predetermined interval (B) and having a predetermined length (D) in the sub-scanning direction; , A pair of cylindrical lenses (second condensing means) 40a and 40b arranged below the filter 16, and arranged below the cylindrical lenses 40a and 40b and held by supporting glass plates 41a and 41b. Of the original 42, a reading lens (third condensing means) 44 arranged below the original 42 and condensing the transmitted light irradiated on the original 42, and the reading lens 44. By the lens 44 preparative said read disposed part and a line sensor 46 for converting into an electric signal by receiving light focused. The filter 16 is
The pair of cylindrical lenses 40a and 40b are arranged at the front focus position.

The image reading optical device 30 according to the present embodiment is
It is basically configured as described above, and its operation and action will be described next.

The reading light emitted from the light source 32 is condensed in the sub-scanning direction by the cylindrical lens 34, and then the filter 16 is passed through the slit 36 of the field stop 38.
Be led to. The reading light introduced into the filter 16 is
It is introduced into the pair of cylindrical lenses 40a and 40b. The cylindrical lenses 40a and 40b form the image of the slit 36 on the original 42 and focus the reading light on the original 42. The reading light transmitted through the original 42 is condensed through a reading lens 44, and a line sensor 46
It is condensed as linearized light. Therefore, the line sensor 46 main-scans the document 42 conveyed in the sub-scanning direction, converts the reading light carrying image information into an electric signal,
It is transferred as image data to an image processing circuit (not shown) of the image reading apparatus.

In this case, the filter 16 can reduce the visual recognition of scratches on the original 42 in the sub-scanning direction, as described with reference to FIGS. Further, as shown in the characteristic of FIG. 7, the filter 16 is provided with first and second print patterns 24 and 25 having a predetermined length (D) in the sub-scanning direction. , Second print patterns 24, 25 and the first and second print patterns 2
Since the amount of light in the sub-scanning direction is controlled by the transmissive portions other than 4 and 25, the visual recognition of scratches in the main scanning direction can be reduced.

Next, a filter 50 according to another embodiment is shown in FIG. This filter 50 has spacers 54a and 54b at the ends of two transparent glass plates 52a and 52b, and chromium (Cr) having a predetermined width (C) on the inner surfaces of the glass plates 52a and 52b facing each other. ) Is vapor-deposited at a predetermined interval (B) to form a first print pattern 56 and a second print pattern 57, respectively.
By making the inside hollow, a light transmissive member is formed. In this case, there is no possibility that dust or the like will enter between the glass plates 52a, 52b, and the glass plates 52a, 5b
It is possible to obtain the effect of facilitating the cleaning of the outer surface of 2b.

Furthermore, a filter 60 according to another embodiment is shown in FIGS. 9 and 10. The filter 60 is a cylindrical aluminum pipe (light non-transmissive member) 64 in which a slit 62 is defined in the longitudinal direction, and a circle which is inserted into the aluminum pipe 64 and introduces light from a light source 66. A columnar quartz glass body (introducing member) 68 and a substantially same light-attenuating member having a predetermined width (C) in the longitudinal direction of the outer peripheral surface of the glass body 68 are arranged at the same interval (B) as the predetermined width (C). ), And a plurality of first print turns 70 that are arranged apart from each other,
Glass body 68 facing the first print pattern 70
Formed substantially the same on the outer peripheral surface of the first print pattern 7
The second print pattern 71 corresponds to the position of 0 and the position of the interval (B). When the glass body 68 is fitted into the aluminum pipe 64, the second print pattern 71 is arranged at the slit 62. A diffusion coating layer (not shown) for diffusing light is attached to the inner wall surface of the aluminum pipe 64. Note that, instead of the glass body 68, the inside of the aluminum pipe 64 is made hollow, the first print pattern 70 is formed on the inner wall surface, and the slit 62 is provided with a second plate via an acrylic plate or the like.
The print pattern 71 may be formed.

The operation and effect of the filter 60 constructed as above will be described below.

The reading light emitted from the light source 66 arranged near one end of the glass body 68 is introduced into the aluminum pipe 64 through the glass body 68. The reading light introduced into the aluminum pipe 64 is reflected by the diffusion paint layer provided on the inner wall surface of the aluminum pipe 64, and the reading light is scattered. In this case, the reading light L14 reflected by the portion other than the first print pattern 70 and scattered without passing through the second print pattern 71 is emitted to the outside of the filter 60 without being dimmed. On the other hand, the reading light L15 that is reflected by the first print pattern 70 and does not pass through the second print pattern 71, and the reading light L16 that passes through the second print pattern 71 are attenuated in their light quantities and are outside the filter 60. Is injected into. In this way, it is possible to obtain the same characteristics as in FIG. 2 with the read light that is dimmed and the read light that is not dimmed.

In this embodiment, the transmissive originals 14 and 42 have been described, but it goes without saying that they may be reflective originals.

[0031]

According to the image reading optical device of the present invention, the following effects can be obtained.

That is, the light amount of the reading light incident on the original is controlled by the angle, and the reading light is guided to the line sensor through the light condensing means having the numerical aperture corresponding to the angle. It is possible to make scratches and the like in the main scanning direction inconspicuous.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of an image reading optical device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a light amount of light incident on a document and an irradiation angle.

FIG. 3 is an explanatory diagram showing a relationship between an incident angle of read light incident on a filter and a transmittance.

FIG. 4 is an explanatory diagram showing luminance characteristics of a normal diffused light source.

FIG. 5A is an explanatory diagram showing the action of the filter when the document is not scratched, and FIG. 5B is an operation diagram when the document is scratched.

FIG. 6 is a configuration diagram showing an image reading optical device according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing the relationship between the light amount of light and the irradiation angle with respect to the sub-scanning direction.

FIG. 8 is a cross-sectional view of a filter according to another embodiment.

FIG. 9 is an exploded perspective view of a filter according to another embodiment.

10 is a vertical cross-sectional view of the filter shown in FIG.

[Explanation of symbols]

 10, 30 ... Image reading optical device 12, 32, 66 ... Light source 14, 42 ... Original document 16, 50, 60 ... Filter 18, 44 ... Reading lens 20, 46 ... Line sensor 22 ... Light transmissive member 24, 56, 70 ... 1st print pattern 25, 57, 71 ... 2nd print pattern 26 ... Scratch 34, 40a, 40b ... Cylindrical lens 38 ... Field stop 64 ... Aluminum pipe 68 ... Glass body

Claims (5)

[Claims] 1. An image reading optical device which obtains desired image information by irradiating an original with reading light and receiving transmitted light or reflected light of the original with a line sensor. A filter for controlling the light quantity distribution of the reading light is provided between the document and the recorded original, and the filter has a predetermined width and a predetermined interval, and is provided in a predetermined reduction direction in the longitudinal direction of the line sensor. A first dimming portion having a light characteristic, a predetermined distance from the first dimming portion, and a constant width corresponding to the first dimming portion,
An image reading optical device comprising: a second dimming portion having a predetermined dimming characteristic, which is arranged at regular intervals in the longitudinal direction of the line sensor. 2. The device according to claim 1, wherein the first dimming portion and the second dimming portion are formed of predetermined transmittance portions provided on one surface and the other surface of the glass plate, respectively. An image reading optical device characterized in that. 3. The apparatus according to claim 1, wherein the first dimming portion and the second dimming portion are respectively provided on opposing surfaces of a pair of glass plates that are spaced apart by a predetermined distance. An image reading optical device comprising a transmissivity portion. 4. The apparatus according to claim 1, wherein the first dimming portion and the second dimming portion are each formed of a predetermined reflectance portion provided on the inner wall surface of the cylindrical body so as to face each other. Image reading optical device characterized by. 5. A light source for irradiating a document on which image information is recorded with reading light, a first light collecting unit for collecting the reading light in the sub-scanning direction, and the first light collecting unit. Second condensing means for condensing the reading light in the sub-scanning direction on the front side of the condensing position of the reading light, a light source for irradiating the reading light, and a document on which image information is recorded. A filter that controls the light amount distribution of the reading light, a line sensor that is long in the main scanning direction that receives the reading light from the document and converts the reading light into an electric signal, the document and the line sensor And a third condensing unit that is arranged between the line sensor and the line sensor to condense the reading light from the document to the line sensor, and the filter has a constant width in the sub-scanning direction. At the same time, a predetermined dimming is arranged in the main scanning direction at a constant width and at constant intervals. And a first dimming portion having the property of being separated from the first dimming portion by a predetermined distance, and having a constant width and a constant interval in the main scanning direction between the first dimming portion. An image reading optical device comprising: a second dimming portion having a predetermined dimming characteristic arranged.