JPH09214679A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate limitation of a read speed by using a cathode ray tube for a light source and forming a tube face opposite to an original face to be a plane with respect to the original face so as to obtain a sufficient lighting light quantity. SOLUTION: The light source is made up of a cathode ray tube 1 with a fluorescent screen and provided in the vicinity of a transmission original 2. A tube screen 1a and a fluorescent screen 1b of the cathode ray tube 1 opposed to a side of the original 2 are formed to be planes with respect to the surface of the original 2, but at least either of the screen is formed to be a plane. Image information for reading is formed on a transmission type original 2 such as a film. An image forming means 3 is made of an image forming lens and image information on the original 2 is formed on a face of a read means 4. The read means 4 is a linear line sensor (CCD), in which plural pixels are arranged linearly in the main scanning direction. The tube screen of the cathode ray tube 1 opposed to the original surface is formed to be a plane, then the image information is read at a high speed with an excellent lighting efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, it uses image pickup means (reading means) such as a line sensor or an area sensor to improve the utilization efficiency of illumination light for image information of a document such as a film or OHP. At the same time, the present invention relates to an image reading apparatus that reads with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a document such as a film or OHP is C
As an image reading apparatus for reading using a reading means such as a CD, a configuration as shown in FIGS. 8 and 9 is widely known.

FIG. 8 is a schematic view (sub-scan sectional view) of a main part of a conventional transmissive image reading apparatus. In the figure, the luminous flux from a cylindrical light source (cylindrical light source) 85 and the luminous flux emitted from the light source 85 to the reflecting mirror 88 side and reflected by the reflecting mirror 88 are condensed by a condenser lens 89, and thus transmitted. The mold original 82 is illuminated. The image information on the original 82 is imaged on the surface of the line sensor (CCD) 84 by the imaging optical system 83. The light source 85 and the entrance pupil of the imaging optical system 83 are in a conjugate relationship. In the same figure, the transmission type document 82 is read by scanning (moving) the line sensor 84 in the direction of arrow A.

FIG. 9 is a schematic view (sub-scan sectional view) of a main part of a conventional transmissive image reading apparatus. In the figure, a light flux from a point light source (point light source) 95 and a light flux emitted from the light source 95 to the reflecting mirror 88 side and reflected by the reflecting mirror 88 are condensed by a condenser lens 89, and The transmissive original 82 is illuminated. The image information on the original 82 is imaged on the surface of the area sensor 94 by the imaging optical system 83. In the figure, the transparent image 82 is read by reading the formed image with the area sensor 94.

[0005]

The light source means used in the conventional image reading apparatus merely emits a light beam, and the light source itself has no optical condensing function. Therefore, the amount of illumination light on the document surface tends to be insufficient, and there is a problem that the reading speed of the image reading device is restricted.

As a method for solving these problems, for example, (a) there is a method of driving with a high voltage in order to increase the brightness of the light source itself. However, this method has a problem that the size of the tube forming the light source is increased, the size of the entire device is increased, the amount of heat generated is increased, and the temperature becomes high.

(B) There is a method of attaching a reflection shade near the light source for reflecting the light beam emitted from the light source to the side opposite to the document, to the document side. However, this method has a problem in that the entire apparatus becomes large and the entire apparatus becomes complicated due to an increase in the number of parts.

In order to perform more efficient illumination, there arises a problem that an adjusting means is required for setting the relative positional relationship between the light source and the reflector to a predetermined accuracy.

A first object of the present invention is that the light source means for illuminating a document is composed of a cathode tube, and the tube surface of the cathode tube facing the document surface is flat with respect to the document surface. An object of the present invention is to provide an image reading apparatus which has a high illumination efficiency and is small in size, and which can read image information of a document at a high speed while achieving simplification of the whole.

A second object of the present invention is to configure the light source means for illuminating an original by a cathode tube having a fluorescent screen, and to make the fluorescent surface of the cathode tube flat with respect to the original surface, thereby improving the illumination efficiency. Another object of the present invention is to provide an image reading device capable of reading image information of a document at high speed.

A third object of the present invention is that the light source means for illuminating the original is composed of a cathode tube having a fluorescent surface, and the tube surface of the cathode tube facing the original surface is flat or / or flat with respect to the original surface. Also, by making the fluorescent surface of the cathode tube a flat surface with respect to the document surface, it is possible to simplify the entire apparatus and to improve the illumination efficiency. Further, the entire apparatus is small, and the image information of the document can be read at high speed. It is to provide an image reading device capable of

A fourth object of the present invention is to provide the above-mentioned first, second, and
According to a third object, an image reading device capable of reading black-and-white image information at high speed with high illumination efficiency by a simple and compact device by configuring the reading means by one line sensor (CCD). In offer.

A fifth object of the present invention is to provide the above-mentioned first, second, and
For the third purpose, the reading means is composed of three line sensors in which three line sensors are arranged side by side in the sub-scanning direction, and the color separation means is provided, so that a simple and compact device can efficiently illuminate a color image. An object is to provide an image reading device capable of reading information at high speed.

A sixth object of the present invention is to provide the above-mentioned first, second, and
For the third purpose, the reading means is composed of an area sensor, so that a driving mechanism for the sensor is not provided.
An object of the present invention is to provide an image reading device that can read image information of a document at high speed with a simplified small device with high illumination efficiency.

[0015]

The image reading apparatus of the present invention comprises: (1) The image information of a document illuminated by the light beam from the light source means is imaged on the reading means surface by the image forming means, and the image of the document is read. When reading image information, the light source means has a cathode tube,
The cathode tube is characterized in that the tube surface facing the document surface is a flat surface with respect to the document surface.

(2) When the image information of the document illuminated by the light flux from the light source means is imaged on the reading means surface by the image forming means and the image information of the document is read, the light source means has a fluorescent screen. It is characterized in that it has a cathode tube, and the fluorescent surface of the cathode tube is a plane with respect to the original surface.

(3) When the image information of the document illuminated by the light flux from the light source means is imaged on the reading means surface by the image forming means and the image information of the document is read, the light source means has a fluorescent screen. The cathode tube has a cathode surface, and the cathode surface of the cathode tube is flat with respect to the original surface and / or the fluorescent surface of the cathode tube is flat with respect to the original surface. I am trying.

Particularly, in the above (1), (2) and (3), the reading means is composed of one line sensor in which a plurality of pixels are one-dimensionally arranged in the main scanning direction, and the reading means is A three-line sensor in which three line sensors in which a plurality of pixels are one-dimensionally arranged in the main scanning direction are juxtaposed in the sub-scanning direction; and the reading means two-dimensionally arranges a plurality of pixels in the main scanning direction. And area sensors arranged in the sub-scanning direction.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view (sub-scan sectional view) of a main part of an embodiment 1 of the present invention, and shows an image reading apparatus for reading a transmission type original.

In this embodiment, in the optical path from the light source means 1, in the plane orthogonal to the optical axis, the direction corresponding to the arrangement direction of the plurality of pixels (light receiving elements) of the reading means 4 is the main scanning direction. The direction orthogonal to is the sub-scanning direction.

In FIG. 1, reference numeral 1 denotes a light source means, which is composed of a cathode tube (cold cathode tube) having a phosphor screen and is provided in the vicinity of a transmissive original 2 which will be described later. In the cathode tube 1 in this embodiment, a tube surface (opposing surface) 1a facing the surface of the original 2 and a fluorescent surface 1b are both formed flat with respect to the surface of the original 2. In the present embodiment, both the tube surface 1a on the original 2 side of the cathode tube 1 and the fluorescent surface 1b are formed as flat surfaces, but at least one surface may be flat. Hereinafter, the above-mentioned light source means (cathode tube) 1 is also referred to as "planar light source".

Reference numeral 2 is a transparent original such as a film on which image information for reading is formed. An image forming unit 3 is composed of an image forming lens (image forming optical system), and forms image information on the document 2 on a surface of a reading unit 4 described later. 4 is a one-dimensional line sensor (CC
D), in which a plurality of pixels are arranged one-dimensionally in the main scanning direction.

Next, the document reading operation of this embodiment will be described.

In the present embodiment, the original 2 is directly illuminated by the light beam from the flat light source 1, and the image information on the illuminated original 2 is formed on the surface of the one-dimensional line sensor 4 by the imaging lens 3 at a predetermined magnification. I'm making you image. Then, the relative position between the original 2 and the one-dimensional line sensor 4 is changed, and in the present embodiment, the one-dimensional line sensor 4 is moved (scanned) in the direction of arrow A (sub-scanning direction) in the figure, so that the original 2 The one-dimensional line sensor 4 sequentially reads the above two-dimensional image information.

Next, the structure of the flat light source 1 of this embodiment will be described.

The flat light source 1 is configured as a tube having a hollow portion which is long in the direction perpendicular to the paper surface (main scanning direction), and mercury gas, argon gas, xenon gas, etc. are filled in the hollow portion of the tube. It is enclosed. When a silver halide film or the like is used as a transmissive original as the flat light source 1, there is a possibility that the heater may be warped and deformed in the vicinity due to the characteristics of the material since the heating element may be present in the vicinity. A cold-cathode tube is used which has a small amount and can be arranged close to the document and has a good illumination effect. In the present embodiment, the tube surface on the original 2 side of the inner wall of the hollow portion of the flat light source 1 is set to the original 2
The surface is a flat surface and the flat surface 1b is coated with a phosphor.

Here, the difference in illumination light when the flat light source 1 of the present embodiment and the conventional cylindrical light source 5 are used is shown in FIG.
This will be described with reference to FIG. 2 and 3, in FIGS. 1 and 8
The same elements as those shown in are given the same reference numerals.

FIG. 2 is an explanatory view showing the luminous flux emitted from the flat fluorescent surface 1b of the flat light source 1 of this embodiment, and FIG. 3 is emitted from the circular fluorescent surface 85b of the conventional cylindrical light source 85. It is explanatory drawing shown about the luminous flux.

In FIG. 2, b is the fluorescent screen 1b of the flat light source 1.
A light beam of the vertical component with respect to the fluorescent surface 1b of the light beam emitted from, theta _b is the angle between the light beam b in the actual illumination light and a vertical component. In FIG. 3, a is a cylindrical light source 85.
Of the light flux emitted from the fluorescent screen 85b of the
It is a light flux of a vertical component with respect to b, and θ _a is an angle formed by the actual irradiation light and the light flux a of a vertical component.

Comparing FIGS. 2 and 3, the fluorescent screens 1b, 1b,
Light flux b (flat light source) vertically emitted from 85b, light flux a
The angle θ _b is smaller than the angles θ _b and θ _a formed by the (cylindrical light source) with the actual irradiation light. Generally, the closer the light beam emitted from the phosphor screen is to the exit surface, the more perpendicular it is,
The luminous flux component has the highest intensity. That is, the closer the angle θ is to 0 degrees, the brighter the light beam becomes. Therefore, it is understood that the illumination with the flat light source 1 of the present embodiment is brighter than the illumination with the conventional cylindrical light source.

As described above, in this embodiment, of the light emitted from the fluorescent screen 1b of the flat light source 1, the angle θ with the emission surface is 0.
The light flux b having an angle component close to a degree can be used to illuminate the transparent original 2, which enables high-speed reading with brighter illumination.

FIGS. 4 and 5 are explanatory views showing the light amount distributions when the flat light source 1 of this embodiment and the conventional cylindrical light source 85 are used as the light source means. As can be seen from FIGS. 4 and 5, the light amount distribution by the flat light source 1 is flatter than the light amount distribution by the cylindrical light source 85. Thus, when the light source is actually incorporated in the apparatus, in the present embodiment, the positional relationship such as the position in the sub-scanning direction and the rotation can be easily adjusted.

Further, in the present embodiment, as compared with the conventional image reading apparatus shown in FIGS. 8 and 9, a reflecting mirror or condenser lens for condensing the light flux emitted from the light source is not required, and therefore the entire apparatus is used. Since it is a flat light source,
The plane light source and the original can be arranged in close proximity to each other, whereby the transparent original can be efficiently illuminated directly from the close distance and the size of the entire apparatus can be reduced.

FIG. 6 is a schematic view (sub-scan sectional view) of essential parts of the second embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

The present embodiment differs from the first embodiment in that the reading means is composed of a three-line sensor, and color image information is read using the color separation means. Other configurations and optical functions are described in Embodiment 1.
This is substantially the same as described above, and thus, a similar effect is obtained.

That is, in the figure, reference numeral 64 is a reading means, which comprises a three-line sensor in which three line sensors each having a plurality of pixels arranged one-dimensionally in the main scanning direction are arranged in parallel in the sub-scanning direction. A color separation unit 13 is provided in front of the 3-line sensor 64, and has three predetermined color lights, such as red (R) color, green (G) color, and blue (B) color, for reading a color image. It consists of multiple color filters that separate the light into colored light. The color separation means is not limited to the above means, and any means may be used as long as it can be separated into three color lights R, G and B.

Next, the document reading operation of this embodiment will be described.

In this embodiment, the flat light source 1 and the original (color image) 2 are arranged close to each other as in the first embodiment, and the original 2 is directly illuminated by the light flux from the flat light source 1.
An image forming lens 3 forms color image information on the illuminated original 2.
Through the color separation means 13 through three predetermined color lights R,
Color separation is made into G and B, and an image is formed on the surface of the 3-line sensor 64 at a predetermined magnification. The original 2 and the 3 line sensor 6
In this embodiment, the three-line sensor 64 is moved (scanned) in the direction of arrow A (sub-scanning direction) in the figure by changing the relative position with respect to No. Are sequentially read by the 3-line sensor 64.

As described above, in the present embodiment, the color image information of the original 2 can be read with high accuracy by a simplified and small device with high illumination efficiency.

FIG. 7 is a schematic view (sub-scan sectional view) of essential parts of a third embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

The present embodiment differs from the first embodiment described above in that the reading means is composed of an area sensor, and other configurations and optical functions are substantially the same as those of the first embodiment. Is getting

That is, in the figure, reference numeral 74 is a reading means, which is composed of an area sensor in which a plurality of pixels are two-dimensionally arranged in the main scanning direction and the sub scanning direction.

Next, the document reading operation of this embodiment will be described.

In this embodiment, the flat light source 1 and the original 2 are arranged close to each other as in the first embodiment, and the original 2 is directly illuminated by the light flux from the flat light source 1, and the illuminated original is illuminated. The image information on 2 is transferred to the area sensor 7 by the imaging lens 3.
The images are read by being imaged on the four surfaces at a predetermined magnification.

As described above, in this embodiment, as compared with the first and second embodiments described above, the driving mechanism for the sensor section is not provided,
The image information on the original 2 can be read with high illumination efficiency with a simpler and smaller device.

[0046]

According to the present invention, an image reading apparatus capable of obtaining the following effects can be achieved.

According to the first aspect of the present invention, the cathode tube is used as the light source means, and the tube surface (opposing surface) facing the document surface is formed as a flat surface with respect to the document surface. Since it is possible to bring them closer to each other, the size of the entire apparatus can be reduced, and the number of constituent members can be reduced as compared with the conventional image reading apparatus, so that the entire apparatus can be simplified. Further, since the luminous flux from the light source means can be effectively used, a larger amount of light can be obtained, and the accumulation time of the sensor can be shortened, so that the image can be read at high speed and the F number is dark. Since a lens can be used, a wider degree of freedom can be obtained in lens design.

According to the second aspect of the invention, a cathode tube having a fluorescent screen is used as the light source means, and the fluorescent screen of the cathode tube is formed as a plane with respect to the original surface. Since high-speed image reading is possible and a dark lens with a large F number can be used, a wider degree of freedom can be obtained in terms of lens design.

According to the third invention, a cathode tube having a fluorescent screen is used as the light source means, and the tube surface facing the original surface is a plane with respect to the original surface and / or the fluorescent surface of the cathode tube is the original surface. By forming a flat surface with respect to the surface, it is possible to bring the light source and the original document close to each other, and thereby the overall size of the apparatus can be reduced and the number of constituent members can be reduced as compared with the conventional image reading apparatus. Therefore, the entire device can be simplified. Further, since the luminous flux from the light source means can be effectively used, a larger amount of light can be obtained, and the accumulation time of the sensor can be shortened, so that the image can be read at high speed and the F number is dark. Since a lens can be used, a wider degree of freedom can be obtained in lens design.

According to the fourth invention, the above-mentioned first, second, and
In the third aspect of the present invention, the reading means is composed of one line sensor (one-dimensional line sensor), so that it is possible to actually read a black-and-white image with high illumination efficiency and a high-speed black-and-white image with a simple and compact device. Since it is possible to read easily and use a dark lens with a large F number, a wider degree of freedom can be obtained in the lens design.

According to the fifth invention, the above-mentioned first, second, and
In the third invention, the reading means is composed of three line sensors in which three line sensors are juxtaposed in the sub-scanning direction, and the color separation means is provided, so that a simplified and compact device can achieve high illumination efficiency and can actually perform color printing. Images can be read, color images can be read at high speed, and a dark lens having a large F number can be used, so that a wider degree of freedom can be obtained in terms of lens design.

According to the sixth invention, the above-mentioned first, second, and
According to the third aspect of the invention, by configuring the reading means with an area sensor, a driving mechanism for the sensor is not required, the image can be actually read with high illumination efficiency with a simpler and smaller device, and the image can be read at high speed. Since it is possible to read easily and use a dark lens with a large F number, a wider degree of freedom can be obtained in the lens design.

[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 a schematic view of a main part of a part of the first embodiment of the present invention.

FIG. 3 is a schematic view of a main part of a part of a conventional image reading device.

FIG. 4 is an explanatory diagram of a part of the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a part of a conventional image reading device.

FIG. 6 is a schematic view of a main part of a second embodiment of the present invention.

FIG. 7 is a schematic view of a main part of a third embodiment of the present invention.

FIG. 8 is a schematic view of a main part of a conventional image reading device.

FIG. 9 is a schematic view of a main part of a conventional image reading device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 light source means (flat light source) 2 original 3 image forming means 4 reading means (one-dimensional line sensor) 13 color separation means 64 reading means (3 line sensor) 74 reading means (area sensor) 88 reflecting mirror 89 condenser lens 85 cylindrical shape Light source 95 Point-shaped light source a, b Vertical emission luminous flux θ _a , θ _b Angle formed by irradiation light and vertical emission light

Claims (6)

[Claims] 1. When the image information of a document illuminated by a light beam from the light source means is imaged on the surface of the reading means by the image forming means and the image information of the document is read, the light source means has a cathode tube. In the image reading apparatus, a tube surface of the cathode tube facing the document surface is a flat surface with respect to the document surface. 2. When the image information of the original document illuminated by the light beam from the light source means is imaged on the reading means surface by the image forming means and the image information of the original document is read, the light source means has a cathode having a fluorescent surface. An image reading apparatus having a tube, wherein the fluorescent surface of the cathode tube is a flat surface with respect to the original surface. 3. The image information of the original document illuminated by the light flux from the light source means is imaged on the surface of the reading means by the image forming means, and when the image information of the original document is read, the light source means has a cathode having a fluorescent surface. The cathode tube has a tube surface, the tube surface facing the original surface is a flat surface with respect to the original surface, and / or the fluorescent surface of the cathode tube is a flat surface with respect to the original surface. Image reading device. 4. The image reading apparatus according to claim 1, wherein the reading unit is composed of one line sensor in which a plurality of pixels are one-dimensionally arranged in the main scanning direction. 5. The reading means includes a line sensor, in which a plurality of pixels are one-dimensionally arranged in the main scanning direction, in the sub scanning direction.
4. The image reading apparatus according to claim 1, wherein the image reading apparatus comprises three line sensors arranged side by side. 6. The image reading device according to claim 1, wherein the reading unit is an area sensor in which a plurality of pixels are two-dimensionally arranged in a main scanning direction and a sub scanning direction.