JP2785758B2 - Linear light source - Google Patents

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, and more particularly, to a linear light source using a light emitting diode mounted on an image input device such as a facsimile or a handy scanner.

[0002]

2. Description of the Related Art A linear light source mounted on an image input device such as a facsimile or a handy scanner is required to uniformly and efficiently irradiate a linear area. A linear light source having a configuration arranged in a shape is known (Japanese Patent Publication No. 3-40551).

FIG. 6 is an external view of an example of this conventional linear light source, and FIGS. 7A and 7B are lines AA 'and BB' in FIG.
The sectional views along the line are shown. 6 and 7, the linear light source includes a printed board 1, a reflection frame 2 provided on the printed board 1, a rod-shaped lens 3 attached to the reflection frame 2, and a line on the printed board 1. And light emitting diodes (LEDs) 6 of a chip type arranged in a matrix. The LED 6 is connected to the lead wire 7.

Here, the reflection frame 2 has a semi-circular curved surface as shown in FIG. 7 (B), and a flat shape having an obliquely inclined cross section as shown in FIG. 8 (A). , FIG.
(B) a cross section having an elliptical curved surface,
A cross section having a parabolic curved surface as shown in FIG. 8C is conventionally known (Japanese Patent Laid-Open No. 59-1431).
No. 45).

Next, the operation of the conventional linear light source shown in FIGS. 6 to 8 will be described. A part of the light emitted from the LED 6 in all directions is directly incident on the rod-shaped lens 3 to change its course, and is placed on the original 5 shown in FIG. Narrow linear area (light irradiation surface 4)
Is irradiated. In addition, as shown in FIG. 8, a part of the light emitted from the LED 6 in all directions is reflected by the reflection frame 2 and then similarly enters the rod-shaped lens 3 and reaches the light irradiation surface 4. In this case, as shown in FIGS. 7 (B), 8 (B), and 8 (C), when the reflecting frame 2 is configured to have a curved reflecting surface, the light radiated from the LED 6 can be efficiently emitted. Light can be collected.

Here, a linear light source mounted on an image input device such as a facsimile or a handy scanner is usually 4 mm.
A light irradiation surface 4 having a width of about 1 mm is positioned at a distance of about 5 mm.
It is designed to form The LED 6 is a cubic chip type having a side of about 0.3 mm, and is used in combination with the rod-shaped lens 3 having a diameter of about 4 mm to 5 mm. Therefore, the thickness of the entire linear light source is 6 mm to 8 mm.
mm, the total length from the linear light source to the light irradiation area is 10 m
m to about 13 mm.

[0007]

In order to further reduce the size of an image input device such as a facsimile or a handy scanner, the size of the linear light source itself mounted on the image input device is reduced, and the size of the linear light source is increased. It is necessary to irradiate a closer place with a narrower width. However, in the conventional linear light source shown in FIG. 6 and FIG.
By reducing the distance between the two reflection frames 2,
Although the light directly incident on the rod-shaped lens 3 can be condensed in a narrow area, the light reflected by the reflection frame 2 is collected at another place, so that the light use efficiency is deteriorated.

If the rod-shaped lens 3 and the reflection frame 2 are made smaller in a similar manner, it is possible to reduce the size of the linear light source to some extent without sacrificing light use efficiency. However, the separation width on the LED 6 side between two adjacent reflection frames 2 is L
Since there is a structural restriction that the size of the rod lens 3 cannot be narrowed beyond the width of the ED 6, there is a minimum value for the size of the rod-shaped lens 3 that can be used, and the size cannot be reduced below the minimum value.

As described above, the conventional linear light source has a problem that the degree of freedom in design is small. For example, it is difficult to realize a linear light source with a thickness of 5 mm or less that irradiates a place of about 1 mm to 2 mm away from the linear light source with a width of 1 mm or less. As described above, in the conventional linear light source, the size of the rod-shaped lens 3 to be used is limited, so that it is difficult to sufficiently reduce the size.

[0010] The present invention has been made in view of the above points,
An object of the present invention is to provide a linear light source with a smaller shape by eliminating the structural restriction on the arrangement of the reflection frame and the light emitting diodes.

It is another object of the present invention to provide a linear light source having high light use efficiency.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a light emitting device having a plurality of light emitting elements arranged linearly on a substrate, a reflective layer provided on the substrate, and a light emitting element on a reflective surface. Reflection means provided on the substrate so as to be spaced apart by a certain inner curved surface and having a concave cross-sectional shape of the inner curved surface, fixedly supported by an opening formed in a part of the reflection means, and emitted from the light emitting element. And the refraction means for receiving the light reflected directly by the reflection means and the reflection layer and condensing and irradiating the light to a linear irradiation area at a position separated by a certain distance. It is configured.

According to another aspect of the present invention, there is provided a light-emitting device having a plurality of light-emitting elements arranged on a transparent substrate and provided on the transparent substrate so as to cover the light-emitting elements with an inner curved surface which is a reflection surface. In addition, a reflecting means having a concave cross section of an inner curved surface is provided on a surface of the transparent substrate opposite to the reflecting means, and light emitted from the light emitting element and transmitted through the transparent substrate is incident thereon. And a refraction means for converging and irradiating a linear irradiation area at a position separated by a certain distance.

Further, according to the present invention, in place of the reflecting means and the refracting means on the transparent substrate, the light emitting element is separately covered by an inner curved surface which is a reflecting surface, and the inner curved surface has an elliptical cross section. A light-collecting means provided on a transparent substrate is provided so that the light-emitting element is arranged at one of the focal points, and a linear irradiation region is provided at the other position of the focal point of the elliptical cross section of the inner curved surface of the light-collecting means. Is formed.

In the present invention, since the light emitting element is covered by the reflecting means having a concave curved inner surface, the light emitting element is mounted on a reflecting frame (reflecting means) such as a conventional light source in which the light emitting element is mounted on the reflecting frame. It is possible to eliminate restrictions on the configuration of the arrangement of the light emitting elements.

According to the present invention, in addition to the light directly incident on the refraction means from the light emitting element, the light reflected multiplely by the reflection means and the reflection layer having a concave inner curved surface so as to cover the light emitting element. Since the light also enters the refracting means, the amount of light incident on the refracting means can be increased.

According to the present invention, a reflecting means for covering a plurality of light emitting elements on the transparent substrate with a concave inner curved surface in cross section is provided on the transparent substrate, or an inner curved surface having an elliptical cross sectional shape is provided. Is provided on the transparent substrate so that the light-collecting means is spaced apart from the light-emitting element. Therefore, there is a limitation on the arrangement of the reflection frame (reflection means) and the light-emitting element as in the conventional light source in which the light-emitting element is mounted on the reflection frame. Can be eliminated.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a linear light source includes a printed board 11 and a plurality of cubic light emitting diodes (LEDs) 16 linearly provided on the printed board 11.
And a reflecting means 12 provided on the printed circuit board 11 so as to cover the LED 16 at a certain distance, and a round bar-shaped refracting means 13 attached to a central portion of the reflecting means 12. The LED 16 is connected to the printed circuit board 11 via a lead 17.

FIG. 2A is a plan view of the printed circuit board 11. As shown in FIG. 1, a plurality of first pads 14 and a plurality of second pads 15 are regularly arranged on the printed circuit board 11 while being separated from each other. The first of each
The LEDs 16 are mounted on the pads 14 and in a linear shape in the longitudinal direction of the printed circuit board 11.
16 is connected on the second pad 15. here,
The first pad 14 and the second pad 15 are set to have a high light reflectance by silver plating, solder plating, or the like.

FIG. 2B shows the reflection means 12 and the refraction means 13.
FIG. 2 is a cross-sectional view of FIG.
As shown in the figure, a hollow semi-cylindrical reflecting means 12 is mounted on a printed circuit board 11, and the reflectance of light on an inner curved surface facing the LED 16 is set high. The reflecting means 12 may have a hollow semi-elliptical, semi-parabolic curved surface or a planar reflecting surface. In the present specification, these curved surfaces are collectively referred to as concave surfaces.

Further, the reflecting means 12 has an opening partially, and fixes the refracting means 13 such as a rod-shaped lens.
To support. The cross-sectional shape of the refracting means 13 is circular in this embodiment, but is not limited to a circular shape. Further, although the reflecting means 12 and the refracting means 13 are separately formed and combined, the reflecting means 12 and the refracting means 13 may be integrally manufactured by a method such as injection molding of an optical plastic material.

Next, the operation of the first embodiment will be described. A part of the light radiated from the bonding surface of the LED 16 in all directions is directly incident on the refracting means 13 and is collected to some extent, and irradiates a document (not shown) located at a certain distance from the refracting means 13. Another part of the light emitted from the bonding surface of the LED 16 in all directions is:
After being reflected by the reflection means 12, the light is reflected again by the pads 14 and 15 on the printed circuit board 11, the optical path is changed, and the light is incident on the refraction means 13 and is irradiated onto the original. Therefore, as a result of the multiple reflections between the reflection means 12 and the pads 14 and 15, the amount of light incident on the refraction means 13 is increased, and the linear light source can be reduced in size without sacrificing the light utilization rate. .

Next, the illuminance of the linear light source according to the first embodiment will be described with reference to FIG. 3 in comparison with the illuminance of the conventional linear light source shown in FIG. Here, the conventional linear light source shown in FIG.
Are arranged at a pitch of 2.8 mm, and the diameter D is 4.4 m.
It is configured by combining m rod-shaped lenses 3.

On the other hand, the linear light source according to the first embodiment shown in FIG. 1 is manufactured by removing the rod-shaped lens 3 and the reflection frame 2 of the above-mentioned conventional linear light source, and mounting the optical system produced this time.
The optical system prototyped this time is one in which an opening is provided in a semi-cylindrical reflection frame and a cylindrical glass having a diameter D of 2.0 mm is combined. This reflective frame was produced by cutting a general-purpose tube for gas piping (inner diameter 4.0 mm, outer diameter 6.4 mm) in half vertically and providing an opening at a place where the cylindrical glass was fixed.

A distance H from these two types of linear light sources
An image sensor using a charge transfer device (CCD) is installed at a distant place, and the distribution of the amount of light captured by the image sensor is observed. FIG. 3 shows the results.

In the same figure, the light quantity distribution of the linear light source according to the present embodiment is indicated by black circles, and the light quantity distribution of the linear light source having the structure of FIG. 6 is indicated by white circles. It can be seen that the linear light source of the embodiment can obtain about 2.4 times the amount of light as compared with the conventional linear light source of FIG.

The increase in the illuminance near the lens (refraction means 13) is due to the improvement of the light condensing ability due to the small lens diameter D and the reduction of the light loss due to the reflection structure. Also,
The irradiation width was narrowed from 3.2 mm to 0.6 mm in half width. Further, the thickness of the linear light source is increased from the conventional 6.5 mm to 4.0.
The thickness can be reduced to 0 mm, and downsizing in the thickness direction can be realized.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a perspective view of a second embodiment of the linear light source according to the present invention, and FIG. 5A is a sectional view of FIG. The linear light source shown in FIG.
A plurality of light emitting diodes (LEDs) 26 linearly provided on the transparent substrate 21;
Reflection means 22 having a concave cross-sectional shape of an inner curved surface provided so as to cover the transparent substrate and the reflection means 2 on the transparent substrate 21.
2 and refraction means 23 attached to the surface on the opposite side.

FIG. 5A shows the linear light source shown in FIG.
1 is a cross-sectional view when cut in a direction orthogonal to the longitudinal direction of the LED. As shown in these figures, the LED 26 is connected to the first pad 24 on the transparent substrate 21,
Is connected to the second pad 25 on the transparent substrate 21. The pads 24 and 25 may be formed small using a metal material, or may be formed using a transparent conductive film.

Next, the operation of this embodiment will be described. The light emitted from the LED 26 in all directions is shown in FIG.
As shown in FIG. 3A, the inner curved surface is reflected by the inner curved surface (the cross-sectional shape is parabolic) of the reflecting means 22 formed on the reflecting surface, passes through the transparent substrate 21, and enters the refracting means 23. Then, the light is refracted and condensed and radiated onto a narrow area of a document (not shown) at a certain distance from the refraction means 23.

Here, since the reflection means 22 is arranged so as to cover the LED 26, almost all of the light emitted by the LED 26 can be guided to the refraction means 23. Also,
Since the cross-sectional shape of the inner curved surface of the reflection means 22 is a parabola, light emitted from one point of the LED 26 in all directions becomes parallel light by being reflected by the reflection means 22. This light is condensed by the refraction means 23 as necessary after transmitting through the transparent substrate 21. Thereby, this embodiment can also realize a reduction in the thickness direction as compared with the related art.

In the second embodiment of the linear light source of the present invention, instead of the reflecting means 22, as shown in FIG.
At one of the elliptical focal points, a condensing means 28 having an LED 26 may be provided. In this case, LED
Light emitted in four directions from 26 is collected by the light condensing means 28 at the other focal point of the elliptical cross section of the light condensing means 28.
Therefore, in this case, since the irradiation area can be optimized by controlling the elliptical shape, the refraction means 23 can be eliminated. Therefore, the modification shown in FIG. 5B can also be downsized in the thickness direction as compared with the conventional example.

It should be noted that the present invention is not limited to the above-described embodiments and modified examples. For example, in place of the LEDs 16 and 26, light emitting elements constituting other point light sources such as lamps can be used in principle. It is.

[0034]

As described above, according to the present invention,
By covering the light emitting element with the reflecting means having a concave cross section of the inner curved surface, the arrangement regarding the arrangement of the reflecting frame (reflecting means) and the light emitting element as in the conventional light source in which the light emitting element is mounted on the reflecting frame. Since the limitation is eliminated, downsizing in the thickness direction can be realized as compared with the conventional light source.

According to the present invention, in addition to the light directly incident on the refracting means from the light emitting element, the light is reflected by the reflecting means and the reflective layer having a concave inner curved surface so as to cover the light emitting element. When the refracted light is also incident on the refraction means, the amount of light incident on the refraction means can be increased, so that the light utilization rate can be improved as compared with the conventional light source.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view of each part of FIG.

FIG. 3 is a diagram showing the performance of the linear light source of FIG. 1 in comparison with a conventional light source.

FIG. 4 is a perspective view of a second embodiment of the present invention.

FIG. 5 is a sectional view of a modification of the sectional view of FIG. 4;

FIG. 6 is an external view of an example of a conventional linear light source.

FIG. 7 is a sectional view taken along lines AA ′ and BB ′ in FIG. 6;

FIG. 8 is a diagram showing each example of a reflection surface shape of a reflection frame of a conventional linear light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Printed circuit board 12,22 Reflecting means 13,23 Refracting means 14,24 First pad 15,25 Second pad 16,26 Light emitting diode (LED) 17,27 Lead wire 28 Light collecting means

Claims (5)

(57) [Claims] A plurality of light-emitting elements arranged linearly on a substrate; a reflective layer provided on the substrate; and a light-emitting element disposed on the substrate so as to cover the light-emitting elements with an inner curved surface that is a reflection surface. Provided in the reflector, the cross-sectional shape of the inner curved surface is concave, and fixedly supported by an opening formed in a part of the reflector,
The light emitted from the light emitting element is directly incident, and the light reflected by the reflection means and the reflection layer is incident, and these lights are condensed and irradiated on a linear irradiation area at a position separated by a certain distance. A linear light source comprising: 2. The method according to claim 1, wherein the substrate is a printed circuit board, and the reflective layer is a first substrate on which each of the plurality of light emitting elements is mounted.
The linear light source according to claim 1, comprising a second pad connected to the light emitting element via a lead wire. 3. A plurality of light-emitting elements arranged on a transparent substrate, and a cross-sectional shape of the inner curved surface provided on the transparent substrate so as to cover the light-emitting elements at a distance from each other by an inner curved surface serving as a reflection surface. A concave reflecting means, provided on a surface of the transparent substrate on the side opposite to the reflecting means, light emitted from the light emitting element and transmitted through the transparent substrate is incident, and the light is separated by a predetermined distance. And a refraction means for converging and irradiating the linear irradiation area. 4. A plurality of light-emitting elements arranged on a transparent substrate, the light-emitting elements are separately covered by an inner curved surface that is a reflection surface, and the inner curved surface has an elliptical cross-sectional shape and is provided at one of its focal points. Light-collecting means provided on the transparent substrate so that the light-emitting element is disposed, and the light-collecting means emits light from the light-emitting element and transmits through the transparent substrate through the light-collecting means. A linear light source, wherein a linear irradiation area is formed at the other position of the focal point of the elliptical cross section of the inner curved surface of the means. 5. The linear light source according to claim 1, wherein the light emitting element is a light emitting diode.