JPH11146142A - Linear light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive linear light source unit where a light from a light source is efficiently led, the light is collected uniformly in a line at an irradiated face and cost reduction of the light source is realized. SOLUTION: A 1st base member 13 (N1) and a 2nd base member 14 (N2) made of a plastic material, whose refractive indices are respectively N1, N2 (N1<N2), are arranged alternately to form nearly a rectangle, the ends of the 1st member 13 and the 2nd member 14 are collected to nearly a middle of one longer side of the rectangle to form a light source section 15, the end of the 2nd member 14 is spread over the other longer side opposed to the 2nd base member 14 to form an irradiating face 16 in the light source unit main body 12, a light source (LED5) is placed to the light source section 15 of the light source unit main body 12, the light from the LED5 is progressed in the 2nd member 14 with a higher refractive index, the light is all reflected from a border with the 1st member 13 and the light is radiated fro the face to obtain a uniform illumination at a linear lighting section D. The number of LEDs is reduced to provide the linear light source unit at a reduced cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear light source unit used as a light source for a facsimile or a personal computer terminal image scanner.

[0002]

2. Description of the Related Art Recently, LED light sources have been widely used as reading light sources for personal facsimile machines.
The fact that LED light sources are the most suitable for miniaturization of these devices, the reduction in the amount of light required due to the increased sensitivity of CCD sensors, and the decrease in the amount of light in the case of LED light sources lead to a decrease in the number of LED chips. It is thought that this is directly linked to cost reduction. In a high-speed facsimile or the like that requires a larger amount of light, a Xe cold-cathode tube, a fluorescent lamp, or the like is used.

As described above, a facsimile or the like includes an LED, a Xe cold-cathode tube, a fluorescent lamp, and the like as a light source for illuminating a document surface with constant brightness in a device for reading the document. The IC incorporates a light receiving element such as a photodiode for reading reflected light of the light. FIG.
FIG. 6 is a cross-sectional view of a general contact image scanner, and FIG.
The outline will be described.

[0004] As shown in FIG.
A document reading light receiving element 1 in which a plurality of pixels for performing photoelectric conversion are arranged, a light receiving element array 4 including a protective film 2 and a substrate 3 on which the document is mounted, an LED 5 as a linear light source for irradiating the document, and a document Is formed by a lens array 6 for forming an image on the sensor light receiving portion, a transparent plate 7 on which a document 9 is placed, and an outer case 8 for supporting these members.

The operation of the contact type image sensor is as follows. A document surface is illuminated by an LED 5 or the like, and diffuse reflection light on a reading line on the document surface is imaged on a sensor pixel row by a lens array 6, and the reflected light is reflected. Each sensor pixel converts the density information of the original 9, that is, the intensity of light, into an electric signal and sequentially sends out the electric signal in the main scanning direction. Then, by moving the relative position between the original 9 and the sensor pixel row in the sub-scanning direction and repeating data transmission in the main scanning direction, two-dimensional image information is converted into a time-series electric signal.

As shown in FIG. 6, in a reduction optical image scanner, a fluorescent lamp 5a or the like is used as a light source for irradiating a document 9, and reflected light on a reading line B of the document 9 is transmitted through a reduction lens 6a. To form an image on the CCD 1a to read the image data on the document surface.

FIG. 7A is a perspective view of a surface mount type LED array light source, and FIG. 7B is a cross-sectional view of FIG. 7A with a reflection frame. In the figure, a plurality of LEDs 5 are mounted on a substrate 10 by soldering or the like to obtain a linear light source.

FIG. 8 is a graph showing the directional characteristics of the LED. In the figure, the central portion of the light source is high, and decreases toward both sides, forming a substantially egg-shaped curve.

[0009]

However, the LED light source, which is the above-described linear light source, has the following problems. That is, in order to improve the uniformity of the light output, it is necessary to use a large number of LEDs, so that the cost of the linear light source unit is increased.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to efficiently guide light from a light source,
An object of the present invention is to provide an inexpensive linear light source unit that realizes a reduction in light source cost by uniformly condensing light in a line shape on an emission surface.

[0011]

In order to achieve the above-mentioned object, a linear light source unit according to the present invention comprises a first base material and a second base material made of a plastic member and having different refractive indexes, which are alternately arranged. Forming a light source part by concentrating the ends of the first base material and the second base material substantially at the center of one long side of the rectangular shape. A light source unit main body in which the end surface of the second base material is widened to form an emission surface over the entire other long side opposed to the light source, and a light source is disposed in the light source unit of the light source unit main body, and the light source exits the light source. The light travels through the second base material having a large refractive index, is reflected at the boundary with the first base material having a small refractive index, and is emitted at the emission surface, so that the light is uniformly emitted to the linear illumination unit. It is characterized by obtaining an excellent illumination.

Further, the light source is an LED.

[0013] The light-emitting portion forming the light source section may have an emission periphery covered with the second base material.

In the light source having directivity, the width of the emission surface of the second base material of the light source unit main body is wider toward the center of the light source, and becomes narrower toward both ends, so that the line-shaped illumination portion is formed. It is characterized by obtaining uniform illumination.

In the light source having directivity, the width of the incident surface of the second substrate in the light source unit of the light source unit main body is wider at a position directly above the light source and narrower toward both right and left ends. It is characterized in that uniform illumination is obtained in the linear illumination section.

Further, a plurality of the light source unit bodies are laminated to form a light source unit assembly, and a light source is provided in a light source section of the light source unit assembly, and the light emitted from each light source has a refractive index. By proceeding through the large second base material, reflecting at the boundary with the first base material having a small refractive index, and emitting light at the emission surface, uniform illumination can be obtained in the linear illumination part. It is assumed that.

Further, a plurality of the light source unit main bodies are continuously formed in the longitudinal direction to form a light source unit assembly, and a light source is provided in a light source portion of the light source unit assembly. By proceeding through the second base material having a large refractive index, reflecting the light at the boundary with the first base material having a small refractive index, and outputting the light at the emission surface, uniform illumination is obtained in the linear illumination part. It is characterized by the following.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A linear light source unit according to the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention. FIG. 1 is a perspective view of a linear light source unit, and FIG. 2 is a front view of the linear light source unit showing the optical path of FIG. In the drawings, the same members as those of the prior art are denoted by the same reference numerals.

In FIG. 1, reference numeral 11 denotes a linear light source unit, and a light source unit main body 12 and an LED 5 serving as a light source.
It is composed of The light source unit main body 12 is formed in a substantially rectangular shape by alternately arranging first base materials 13 made of a plastic member or the like having a refractive index N1 so as to sandwich a second base material 14 having a refractive index N2. ing. The first substrate 1
There is a relationship of N1 <N2 between the refractive index N1 of No. 3 and the refractive index N2 of the second base material 14. A light source unit 15 in which the ends of the two base materials 13 and 14 are concentrated is formed in a substantially central portion of one long side of the rectangular shape of the light source unit body 12,
The end portion of the second base member 14 extends over the entire other long side facing the light source portion 15. The second base material 14 forms the emission surface 16. Therefore, the width B of the emission surface 16 is formed wider than the width A of the adjacent first base material 13. The light source L is provided on the substrate 10 of the light source unit 15.
ED5 is surface-mounted.

Referring to FIG. 2, the operation of the linear light source unit 11 having the above configuration will be described. The light C emitted from the LED 5 disposed in the light source unit 15 is transmitted to the second base material 14 having the refractive index N2 and reflected at the boundary with the first base material 14 having the refractive index N1. The light is emitted from the emission surface 16 that spreads in a fan shape, and the linear irradiation part D can be uniformly and efficiently illuminated.

FIG. 3 is a front view showing an optical path of a linear light source unit according to a second embodiment of the present invention. A light source having a directivity as shown in FIG.
Considering the directional characteristics of the light source unit body 12,
In the emission surface 16 spreading in a fan shape, the size of the emission surface 16 at the end of the second base material 14 is such that the width B1 becomes wider toward the center of the LED 5 and the widths B2 and B3 become narrower toward both ends. And the light C emitted from the LED 5 can uniformly and efficiently illuminate the linear irradiation part D in the same manner as described above.
Note that, depending on the directivity of the light source, the width of the emission surface 16, B1,
B2 and B3 etc. are changed appropriately, and B2 and B3 are not necessarily changed.
It is not limited to 1>B2> B3.

In the light source having directivity, the area of the light exit surface 16 is corrected as described above, but the width of the incident surface of the second base material 14 in the light source unit 15 of the light source unit main body 12 is set to A uniform illumination can be obtained in the linear illumination unit D by correcting the area of the line-shaped illumination unit D by widening the position directly above the LED 5 and narrowing the distance to the left and right ends, and correcting the area of the incident surface.

FIG. 4 is a perspective view of a linear light source unit in which a plurality of light source unit bodies are stacked. In FIG. 4, reference numeral 11A denotes a laminated linear light source unit. In the laminated linear light source unit 11A, a plurality of, for example, three light source unit main bodies 12 are laminated to form a light source unit assembly 12A, and the light source unit 15 of the light source unit assembly 12A is a light source. The LED 5 is mounted. The light emitted from the LED 5 travels into the second base material 14 having a large refractive index, is reflected at a boundary with the first base material 13 having a small refractive index, and is emitted at the emission surface. Thereby, uniform illumination can be efficiently obtained in the linear illumination section.

Since it is necessary to take in more light into the second base member 14 around the LED 5 forming the light source section 15, the width of the incident surface of the second base member 14 is reduced by the first base member. 1
It is better that the width is larger than the width of the entrance surface of No. 3. The periphery of the LED 5 may be covered with the second substrate 14 or may be embedded in the second substrate 14.

A plurality of light source unit main bodies 11 are connected in the longitudinal direction to form a light source unit assembly (not shown), and a light source is provided in a light source section of the light source unit assembly. Light that has a large refractive index
Of the first base material 13 having a small refractive index
By reflecting the light at the boundary with the light emission surface and emitting the light at the emission surface, uniform illumination can be obtained in the linear illumination unit.

In the above embodiment, the light source is L
Although the ED is used, it is needless to say that a fluorescent lamp or the like may be used instead of the LED.

[0027]

As described above, according to the present invention,
In a linear light source unit, a light source is provided in a light source unit of a light source unit body formed of a first base material and a second base material made of a plastic member and having different refractive indexes, and light emitted from the light source is refracted. Since the light travels into the second base material having a high refractive index and is totally reflected at the boundary with the first base material having a low refractive index, the light amount of the light source can be efficiently converted into a linear shape. The number of LEDs used can be reduced, and a low-cost linear light source unit can be provided.

Further, by covering the emission area of the light source with the second base material, the light amount of the light source can be used without waste.

Further, in the light source having directivity, the area of the emission surface of the second base material of the light source unit main body, or
By correcting with the area of the incident surface, uniform illumination can be obtained in the linear illumination section.

Further, a plurality of the light source unit main bodies are laminated, or a plurality of the light source unit main bodies are continuously formed in the longitudinal direction to form a linear light source unit. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view of a linear light source unit according to a first embodiment of the present invention.

FIG. 2 is a front view of a linear light source unit showing an optical path of FIG. 1;

FIG. 3 is a front view showing an optical path of a linear light source unit according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a laminated linear light source unit according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a conventional contact image scanner.

FIG. 6 is a diagram illustrating the principle of a conventional scanner device using a reduction optical system.

FIG. 7A is a perspective view of a surface mount LED array,
FIG. 7B is a cross-sectional view in a state where the reflection frame is provided in FIG.

FIG. 8 is a graph showing directivity characteristics of an LED.

[Explanation of symbols]

 Reference Signs List 5 LED (light source) 11 Linear light source unit 11A Stacked linear light source unit 12 Light source unit main body 12A Light source unit assembly 13 First substrate (refractive index N1) 14 Second substrate (refractive index N2) 15 Light source Part 16 Emission surface A Width of first base material B Width of emission surface of second base material C Optical path D Linear illumination part

Claims (7)

[Claims] 1. A substantially rectangular shape is formed by alternately arranging first base materials and second base materials made of a plastic member and having different refractive indices. Forming a light source portion by concentrating the end portions of the first base material and the second base material, and extending the end portion of the second base material over the entire other long side opposed to the light source portion. A light source unit main body having an emission surface, and a light source disposed in a light source section of the light source unit main body. The light emitted from the light source is caused to travel through a second base material having a large refractive index, thereby obtaining a refractive index. By reflecting light at the boundary with the first base material having a small size and emitting light at the emission surface,
A linear light source unit for obtaining uniform illumination on a linear illumination unit. 2. The linear light source unit according to claim 1, wherein the light source is an LED. 3. The linear light source unit according to claim 1, wherein an emission periphery of the light source forming the light source section is covered with the second base material. 4. A light source having directivity, wherein a width of an emission surface of a second base material of the light source unit main body is wider toward a center position of the light source, and becomes narrower toward both ends, so that a linear illumination unit is formed. 2. A uniform illumination is obtained.
3. The linear light source unit according to 3. 5. In the light source having directivity, the width of the incident surface of the second base material in the light source unit of the light source unit main body is wider as the position directly above the light source, and becomes narrower toward both right and left ends. 4. The linear light source unit according to claim 1, wherein uniform illumination is obtained in the linear illumination unit. 6. A light source unit assembly is formed by laminating a plurality of the light source unit bodies, and a light source is provided in a light source section of the light source unit assembly. It is possible to obtain uniform illumination in the linear illumination section by advancing through the large second base material, reflecting the light at the boundary with the first base material having a small refractive index, and outputting the light at the emission surface. Characteristic linear light source unit. 7. A light source unit assembly is formed by connecting a plurality of the light source unit main bodies in the longitudinal direction, and a light source is disposed in a light source section of the light source unit assembly. By causing the light to travel through the second base material having a large refractive index, to be reflected at the boundary with the first base material having a small refractive index, and to be emitted at the emission surface, uniform illumination can be performed on the linear illumination unit. A linear light source unit characterized by being obtained.