JP2000114603A - Light emitting device and image reading device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bright illumination light whose illuminating efficiency is high by properly setting each element constituting a light emitting device, and to obtain a light emitting device and an image reading device using the light emitting device for realizing highly precise image reading by using the light emitting device as the illuminating means of the image reading device. SOLUTION: This device is provided with a plurality of light source parts 1, first optical functioning part 2 provided corresponding to each of the plurality of light source parts 1 for converting the state of a light flux emitted from each of the plurality of light source parts 1 into a parallel light flux to be transmitted in the same direction to the plurality of light source parts 1, and second optical functioning part 3 for converging each light flux converted into the parallel light flux by the plurality of first optical functioning parts 2 on the same position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and an image reading apparatus using the same, and more particularly to obtaining a bright illumination light with high illumination efficiency from a light emitting device having a simple structure and emitting light from the light emitting device. The image information of a document such as a film is efficiently illuminated using a light beam, and the image information of the document is read with high accuracy by reading means such as a line sensor.

[0002]

2. Description of the Related Art Conventionally, point light sources such as halogen bulbs and linear light sources such as fluorescent lamps have been used as light emitting devices (illumination light sources) used in image reading apparatuses such as film scanners. In the case of a linear light source, the light source itself is a diffused light or has a feature of high luminance, and can illuminate a document (film) or the like with a sufficient amount of light.
On the other hand, when a point-like light source is used, the original (film) is illuminated by condensing a light beam radiated from the point-like light source to the surroundings using a condenser lens or the like to form a parallel light beam or a convergent light beam. And improve the lighting efficiency.

In order to illuminate a certain area using a point light source, a certain distance is required from the position of the point light source to the position to be illuminated. For this reason, for example, as proposed in Japanese Patent Application Laid-Open No. 1-230274, a light beam emitted from a point light source is converted into a parallel light beam via an optical system, and a plurality of these light beams are arranged to obtain a linear light source. When a document is illuminated by condensing a point light source using a condenser lens or the like, the brightness of the illumination light is limited to the brightness of the point light source. In order to obtain brighter illumination, there is a type in which a plurality of point-like light sources are arranged side by side to emit light, which are condensed by a condenser lens or the like, and used as illumination light.

[0004]

When a light beam emitted from a point light source is converted into a parallel light beam via an optical system, and a plurality of these light beams are arranged to form a linear light source, the obtained light beam is a parallel light beam having high directivity. . When an original (film) or the like having low diffusivity is illuminated by the linear light source and an image is formed by forming an image on the original surface, the light flux transmitted through the original is also a highly directional light flux. Therefore, the light collection efficiency for image formation is low. For this reason, measures such as increasing the diameter of the imaging optical system are required.

A plurality of point light sources are arranged side by side to emit light, which are condensed by a condenser lens or the like and used as illumination light. The positions of the plurality of point light sources are different. In order to converge light beams emitted from different positions in a certain area as described above, it is necessary to satisfy a certain positional relationship, such as arranging each point light source in an arc shape. In the case of arranging the prisms linearly, it is necessary to arrange prisms whose bending angles are changed at the positions of the point light sources.

In general, increasing the diameter of an optical system increases the manufacturing cost. In addition, it is difficult to arrange the point light sources with high accuracy to satisfy the positional relationship. In addition, creating prisms having different bending angles and arranging them involves difficulties such as position adjustment during manufacturing.

According to the present invention, it is possible to obtain bright illumination light with high illumination efficiency by appropriately setting each element constituting the light emitting device, and to use the light emitting device as an illumination means of an image reading apparatus. It is an object of the present invention to provide a light emitting device capable of reading an image with high accuracy and an image reading apparatus using the same.

[0008]

According to the present invention, there is provided a light emitting device comprising: (1) a plurality of light source sections and a state of a light beam emitted from each of the plurality of light source sections is directed in the same direction with respect to the plurality of light source sections. A first optical function unit provided for each of the plurality of light source units for converting into a parallel light beam, and respective light beams converted into a parallel light beam by the plurality of first optical function units are collected at the same position. And a second optical function unit for emitting light.

In particular, (1-1) the first optical function section is formed of a concave reflecting surface, (1-2) the first optical function section is formed of a convex lens, (1-3) The concave reflecting surface may be formed of a paraboloid having a light emitting surface of the light source unit as a substantially focal position, or (1-4) the convex lens may be disposed such that a light emitting surface of the light source unit is substantially at a focal position. (1-5) that the second optical function unit is formed of one convex lens, (1-5)
-6) Each of the plurality of light source units has a plurality of light emitting elements, and (1-7) the plurality of light emitting elements have different emission wavelengths.

(2) The image reading apparatus of the present invention illuminates a document with a light beam emitted from a light emitting device, and forms an image of the illuminated light beam from the document on a reading means surface by an image forming optical system. In the image reading apparatus for reading image information of the document, the light emitting device may include a plurality of light source units, and a parallel light beam directed in a same direction with respect to the plurality of light source units by changing a state of light beams emitted from the plurality of light source units. A first optical function unit provided for each of the plurality of light source units for converting the light into a parallel light beam, and the light beams converted into parallel light beams by the plurality of first optical function units are condensed at the same position. And a second optical function unit.

In particular, (2-1) the first optical function section is formed of a concave reflecting surface, (2-2) the first optical function section is formed of a convex lens, (2-3) The concave reflecting surface may be formed of a paraboloid having a light emitting surface of the light source unit as a substantially focal position, or (2-4) the convex lens may be disposed such that a light emitting surface of the light source unit is substantially at a focal position. (2-5) that the second optical function part is formed of one convex lens, (2-5)
-6) Each of the plurality of light source units has a plurality of light emitting elements, and (2-7) each of the plurality of light emitting elements has a different emission wavelength.

[0012]

(Embodiment 1) FIG. 1 (A),
(B), (C) is a schematic diagram of a main part of the light emitting device of the first embodiment of the present invention, respectively. 2A is a front view of the light emitting device as viewed from a direction in which a light beam is emitted, FIG. 2B is a cross-sectional view of a main part of the light emitting device in a longitudinal direction, and FIG. It is a fragmentary sectional view.

In FIG. 1, reference numeral 1 denotes a light source unit, which comprises, for example, a light emitting diode (LED) as a light emitting element.
A plurality are arranged in the dimensional direction (longitudinal direction). Each of the plurality of light source units 1 emits a light beam when an electric current is supplied from the outside through a lead frame or a gold wire (not shown).

Reference numeral 2 denotes a first optical function unit, which is disposed corresponding to each of the plurality of light source units 1. The plurality of first optical function units 2 each have an end surface of the translucent resin 4 facing the light emitting surface of the corresponding light source unit 1 formed in a convex shape, and the convex end surface is mirror-finished by metal deposition or the like. And functions as a concave reflecting surface. The concave reflecting surface is formed of a paraboloid having the light emitting surface of the light source unit 1 as a substantially focal point, and the axes of the parabolic surfaces of the first optical function units 2 are arranged in the same direction. Have been. The plurality of first optical function units 2 in the present embodiment reflect the light emitted from the light emitting surface of the corresponding light source unit 1 in the direction of a second optical function unit 3 described later, and the plurality of light source units 1. Is converted into a parallel light beam directed in the same direction.

Reference numeral 3 denotes a second optical function part, which is composed of, for example, one convex lens formed of a translucent resin or a glass material. The second optical function unit 3 in the present embodiment is arranged and formed so as to cover the plurality of light source units 1 and the plurality of first optical function units 2 provided to face the plurality of light source units 1. Each light beam converted into a parallel light beam by the optical function unit 2 is focused on the same position P.

Reference numeral 4 denotes a light transmitting portion, which is made of, for example, a light transmitting epoxy resin. First optical function unit 2 described above
Is formed on the end face of the light transmitting portion 4.

FIG. 2 is a sectional view of a main part in a longitudinal direction of the light emitting device according to the first embodiment of the present invention and an optical path diagram thereof. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In FIG. 1, a light emitting diode 1 as a light source section is connected via a lead frame (not shown) and gold wires.
When a current is supplied to the light emitting diode 1, a light beam is emitted from the light emitting surface of each light emitting diode 1 toward the corresponding first optical function unit 2. Each of the light beams reflected by the plurality of first optical function units 2 is converted into a parallel light beam directed in the same direction to the plurality of light source units 1 and enters the second optical function unit 3. Each light beam transmitted through the second optical function unit 3 is condensed at an arbitrary position P.

As described above, the light emitting device according to the present embodiment can easily obtain bright illumination light having high light-collecting efficiency with the simple configuration as described above.

(Embodiment 2) FIGS. 3 (A), 3 (B),
(C) is a principal part schematic diagram of the light emitting device of Embodiment 2 of the present invention, respectively. 2A is a front view of the light emitting device as viewed from a direction in which a light beam is emitted, FIG. 2B is a cross-sectional view of a main part of the light emitting device in a longitudinal direction, and FIG. It is a fragmentary sectional view. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

The present embodiment is particularly different from the above-described first embodiment in that the first optical function section is constituted by a convex lens.
That is, the light emitting device is configured by disposing the light source unit on the second optical function unit side. Other configurations and optical functions are substantially the same as those of the first embodiment, and thus the same effects are obtained.

That is, in the figure, reference numeral 12 denotes a first optical function unit, which is arranged corresponding to the plurality of light source units 1. The plurality of first optical function units 12 are each formed of a translucent resin, a glass material, or the like, facing the light emitting surface of the corresponding light source unit 1, and function as convex lenses. The convex lens 12 is disposed so that the light emitting surface of the light source unit 1 is located substantially at the focal position.
The two optical axes are configured to be in the same direction. The plurality of first optical function units 12 in the present embodiment convert the luminous flux emitted from the light emitting surface of the corresponding light source unit 1 into a parallel luminous flux directed in the same direction with respect to the plurality of light source units 1, and perform the second It leads to the optical function unit 3.

FIG. 4 is a longitudinal sectional view of an essential part of a light emitting device according to a second embodiment of the present invention and an optical path diagram thereof. In the figure, the same elements as those shown in FIG. 3 are denoted by the same reference numerals.

In FIG. 1, when a current is supplied to the light emitting diodes serving as the light source unit 1 through a lead frame and a gold wire (not shown), the corresponding first optical function unit 12 is emitted from the light emitting surface of each light emitting diode 1. A light beam is emitted toward the side. Each light beam transmitted through the plurality of first optical function units 12 is converted into a parallel light beam directed in the same direction with respect to the plurality of light source units 1 and is incident on the second optical function unit 3.
Each light beam transmitted through the second optical function unit 3 is condensed at an arbitrary position P.

As described above, the light emitting device according to the present embodiment can easily obtain bright illumination light having high light-collecting efficiency with the simple configuration as described above.

In each of the embodiments described above, the light source unit 1 is constituted by one light emitting diode. However, the present invention is not limited to this. For example, unless the light emitting surface of the light source unit 1 has a large area. A plurality of light emitting diodes may be used. In addition, by using the same light emitting diode as a plurality of light emitting diodes constituting the light source unit 1,
Brighter illumination light can be obtained. Further, by using light emitting diodes having different emission wavelengths as the plurality of light emitting diodes constituting the light source unit 1, illumination light having different wavelength components can be obtained. Further, when a plurality of light emitting diodes constituting the light source unit 1 having different light emission wavelengths are used, the light emitting diodes having different light emission wavelengths are sequentially emitted, respectively, so that light beams having different light emission wavelengths are used, for example, in a color film. Etc. can be illuminated.

In each of the embodiments described above, the plurality of light source units are arranged linearly (one-dimensionally). However, the present invention is not limited to this. For example, a plurality of light source units are arranged on a plane and two-dimensionally arranged. It can also be implemented as a planar light source. This makes it possible to obtain bright planar illumination light with high light-collecting efficiency.

(Embodiment 4) FIG. 5 is a diagram showing the main parts when the light emitting device of the present invention is used in an image reading apparatus such as a film scanner. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In the figure, reference numeral 51 denotes a light emitting device;
It has the configuration shown in the first embodiment. 52
Is a transmission type original such as a film, on which image information for reading is formed. Reference numeral 53 denotes an image forming lens serving as an image forming optical system (imaging optical system), which forms image information of the document 52 on a reading unit surface described later. Reference numeral 54 denotes a line sensor (CCD) as a reading unit, in which a plurality of pixels (light receiving elements) are arranged one-dimensionally.

The second optical function unit 3 in this embodiment condenses the light beams from the plurality of light source units 1 reflected by the plurality of first optical function units 2 near the entrance pupil position of the imaging lens 53. I am trying to do it. That is, each optical element is set so that the light emitting surfaces of the plurality of light source units 1 form images near the entrance pupil position.

In this embodiment, a one-dimensional reading area on the surface of the original 52 is illuminated with a light beam emitted from the light emitting device 51, and image information on the surface of the original 52 is reflected on the line sensor 54 by the imaging lens 53. At a predetermined magnification. By changing the relative position between the document 52 and the line sensor 54, two-dimensional image information on the surface of the document 52 is sequentially read by the line sensor. The light beam transmitted through the document 52 is slightly diffused by the document 52, but most of the light beam enters the imaging lens 53.

As described above, in the present embodiment, by using the light emitting device 51 having the above-described configuration as the illuminating means of the image reading apparatus, the original can be illuminated with bright illuminating light having a high light-collecting efficiency. Image information on the surface of the document 52 can be read with high accuracy by the line sensor 54. In the present embodiment, as shown in FIG. 5, a light beam emitted from the light emitting device 51 transmits through the document 52 obliquely. When the original 52 is a color original, the respective color materials are arranged in layers in the thickness direction of the original. When this is imaged on the surface of the line sensor 54 using the light beam transmitted obliquely, the image formation state differs on the surface of the line sensor 54 due to the color material layer, and color shift or the like may occur. However, in such a case, the light emitting device 51
In synchronization with the wavelength of the luminous flux to be irradiated, for example, the imaging lens 53, the document 52, the line sensor 54, and the like are driven in a predetermined direction, and the color images of the color material layers are easily captured in different imaging states. Can be corrected. Further, the obtained color image can be corrected by performing image processing in post-processing after imaging.

As described above, in the present embodiment, by using the light emitting device 51 described above for an image reading device such as a film scanner, an image on the surface of the original 52 can be captured by effectively using the light amount by the line sensor 54. it can.

[0034]

According to the present invention, it is possible to obtain bright illumination light with high illumination efficiency by appropriately setting each element constituting the light emitting device, and use this light emitting device as illumination means of an image reading apparatus. Thus, a light emitting device capable of reading an image with high accuracy and an image reading apparatus using the same can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view (optical path diagram) of a main part of the light emitting device according to the first embodiment of the present invention in the longitudinal direction.

FIG. 3 is a schematic diagram of a main part of the light emitting device according to the first embodiment of the present invention.

FIG. 4 is a sectional view (an optical path diagram) of a main part in a longitudinal direction of a light emitting device according to a second embodiment of the present invention.

FIG. 5 is a main part configuration diagram when the light emitting device of the present invention is used in an image reading device such as a film scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source part 2,12 1st optical function part 3 2nd optical function part 4 Light transmissive part 51 Light emitting device 52 Document 53 Imaging optical system 54 Reading means

Claims (16)

[Claims] 1. A plurality of light source units and a plurality of light source units that convert a state of light beams emitted from the plurality of light source units into a parallel light beam directed in the same direction with respect to the plurality of light source units. It has a first optical function unit provided for each, and a second optical function unit for condensing each light beam converted into a parallel light beam by the plurality of first optical function units at the same position. A light emitting device characterized by the above-mentioned. 2. The light emitting device according to claim 1, wherein said first optical function part comprises a concave reflecting surface. 3. The light emitting device according to claim 1, wherein said first optical function part is formed of a convex lens. 4. The light emitting device according to claim 2, wherein said concave reflecting surface is a paraboloid having a light emitting surface of said light source section as a substantially focal position. 5. The light-emitting device according to claim 3, wherein the convex lens is arranged so that a light-emitting surface of the light source unit is located substantially at a focal position. 6. The light emitting device according to claim 1, wherein said second optical function part is formed of one convex lens. 7. The light emitting device according to claim 1, wherein each of the plurality of light source units has a plurality of light emitting elements. 8. The light emitting device according to claim 7, wherein the plurality of light emitting elements have different emission wavelengths. 9. An image reading device for illuminating a document with a light beam emitted from a light emitting device, forming an image of the light beam from the illuminated document on a reading unit surface by an image forming optical system, and reading image information of the document. In the apparatus, the light emitting device includes a plurality of light source units, and the plurality of light source units that convert a state of a light beam emitted from each of the plurality of light source units into a parallel light beam directed in the same direction with respect to the plurality of light source units. A first optical function unit provided for each of the plurality of first optical function units;
And a second optical function unit for condensing each light beam converted into a parallel light beam by the optical function unit at the same position. 10. The image reading apparatus according to claim 9, wherein said first optical function section comprises a concave reflecting surface. 11. The image reading apparatus according to claim 9, wherein said first optical function section is formed of a convex lens. 12. The image reading apparatus according to claim 10, wherein the concave reflecting surface is a parabolic surface having a light emitting surface of the light source unit as a substantially focal point. 13. The image reading apparatus according to claim 11, wherein the convex lens is disposed so that a light emitting surface of the light source unit is located substantially at a focal position. 14. The image reading apparatus according to claim 9, wherein said second optical function section is formed of one convex lens. 15. The image reading apparatus according to claim 9, wherein each of the plurality of light sources has a plurality of light emitting elements. 16. The image reading apparatus according to claim 15, wherein the plurality of light emitting elements have different emission wavelengths.