JPH08307607A - Linear light source - Google Patents

Abstract

PURPOSE: To simplify the configuration, and to exclude the increase in a valid light source length with respect to a length of a light source and the effect due to a thermal stress. CONSTITUTION: The light source is provided with a long board 10, plural light source sections 20 each consisting of light emitting elements arranged on the board and a transparent resin 22 covering the light emitting elements. The linear light source 1 is formed by arranging the light source sections on a line on the board 10 along the lengthwise direction apart from each other, the light convergence of a resin 22b forming a light source section 22b at each end of the board is set higher than that of resins 22a forming other light source sections 20a in the plural light source sections 20. Since the light convergence of the resin for the light source section located at the ends of the board is set higher than that of the resins forming the other light source sections, the illuminance at the end of the light source is easily revised without revising light emitting elements to extend the length of the valid light source.

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 in which a plurality of light source parts are linearly arranged along the longitudinal direction of a substrate.

[0002]

2. Description of the Related Art A linear light source used in an image reading apparatus such as a facsimile machine or a copying machine generally has an LE on a substrate.
A light-emitting element composed of a D chip is linearly arranged, and a rod-shaped condenser lens and a reflection frame are arranged along the array (Japanese Patent Laid-Open No. 6-230625).

[0003]

According to the above-mentioned conventional structure, since the rod-shaped condenser lens is provided, it cannot be made thin, and it is difficult to mount it on the contact type image sensor combined with the light receiving line sensor. In addition, since there are many molded parts and adjustment work after assembly is required, assembly workability is poor.

In addition, the illuminance distribution over the entire length of the light source has a flatness at the central portion, but the illuminance drops at the end portions. Therefore, for example, when the total length of the light source is 230 mm, the effective light source length (illuminance deviation value ± 10%). Within) is 210 mm
The length of the light source is about 20 mm, which is not suitable for use.

It is also conceivable to provide a continuous light-transmitting resin that directly covers the LED chip instead of the rod-shaped condenser lens, but the light-transmitting resin warps due to heat stress and the illuminance distribution is disturbed. It tends to occur.

Therefore, the present invention has been made in consideration of the above points, and its main objects are to simplify the configuration, increase the effective light source length with respect to the light source length, and eliminate the influence of thermal stress.

[0007]

A linear light source according to the present invention comprises a long substrate, a plurality of light source portions composed of a light emitting element arranged on the substrate and a translucent resin covering the light emitting element. A linear light source in which the light source units are linearly arranged apart from each other along the longitudinal direction of the substrate, wherein the plurality of light source units are made of a resin that constitutes a light source unit located at an end of the substrate. It is characterized in that the light-collecting degree is made higher than that of the resin constituting the other light source section.

Further, according to the present invention, a long substrate, a light emitting element arranged on the substrate, and a translucent resin covering the light emitting element are formed, and are linearly spaced apart from each other along the longitudinal direction of the substrate. The plurality of light source units are arranged such that the maximum thickness of the light-transmitting resin is substantially constant, and the planar shape of the light-transmitting resin is larger than that of the light source unit at the end and that of the light-transmitting resin. It is characterized in that it is different from the light source section located inside.

Further, according to the present invention, a long substrate, a light emitting element arranged on the substrate, and a translucent resin covering the light emitting element are formed in a linear shape apart from each other along the longitudinal direction of the substrate. A plurality of light source units arranged, the plurality of light source units having a plurality of elliptical light source units in which the plane of the translucent resin forms an elliptical shape, and the planes of the translucent resin in a circular shape or the elliptical shape. And a circular light source having an elliptical shape closer to a circular shape, and the circular light source is arranged at the end of the light source.

[0010]

According to the present invention, since the light source portions are arranged apart from each other along the longitudinal direction of the substrate, warping of the resin due to thermal stress such as when the translucent resin is continuous in the longitudinal direction of the substrate is prevented. It is possible to reduce the variation of the illuminance by almost eliminating it.

Further, in the plurality of light source sections, the light collecting degree of the resin forming the light source section located at the end of the substrate is higher than the light collecting degree of the resin forming the other light source sections, so that the illuminance at the light source end section is increased. It is possible to easily increase the effective light source length without changing the light emitting elements.

Further, in the plurality of light source parts, the maximum thickness of the translucent resin is made substantially constant, and the planar shape of the translucent resin is located at the end light source part and the light source parts located inside thereof. The light condensing degree can be easily changed only by changing the planar shape of the resin, and the illuminance at the end of the light source can be easily changed without changing the light emitting element. Since the thickness of the light source can be made thin and substantially uniform, the light source can be made thin.

In addition, the plurality of light source portions are formed into an elliptical light source portion in which the plane of the light-transmissive resin forms an elliptical shape, and the plane of the light-transmissive resin has a circular shape or a circular shape close to the elliptical shape. The circular light source part is arranged at the end of the light source, and the elliptical light source part can flatten the illuminance distribution by the light buffering (superposition of light) effect. The arrangement pitch of the parts can be lengthened to reduce the number of light source parts. In addition, the translucent resin's planar shape is changed to an ellipse or a circle, which has less unevenness in illuminance and makes it easier to obtain a stable resin shape, so resin molding can be performed easily and stably, and uniform optical characteristics can be achieved. Can be planned.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the linear light source 1 includes a long substrate 10 having an insulating property such as glass epoxy (total length 227 m).
m), a plurality of light source units 20 (40 in this embodiment) are arranged linearly along the longitudinal direction of the substrate 10. The substrate 10 is made of a base material having an insulating property such as glass epoxy, and the surface thereof has electrodes for each light source section 20 and a conductive pattern (not shown) such as a copper foil for connecting these to wiring. And a light insulating film (for example, a white insulating film) having good light reflectivity so as to cover the entire surface of the substrate 10 excluding a predetermined portion (light emitting element arrangement portion, lead wire connection portion, etc.) of the conductive pattern. No) is provided. As shown in FIG. 2, an adhesive layer 30 such as a double-sided tape for attachment is provided on the back side of the substrate 10.

As shown in FIG. 2, each light source section 20 is composed of the same LED chip or the like via a conductive adhesive (not shown) on a conductive pattern formed on the surface of the substrate 10. The light emitting element 21 is arranged, and a resin 22 having a light-transmitting property such as an epoxy resin is molded in a convex lens shape so as to cover the wire bonded light emitting element 21. The light emitting element 21 of each light source unit 20 is made of GaAlAs.
Although it is composed of one LED chip selected from (red), GaP (yellow green) and others, it is also possible to arrange a multicolor light emitting LED chip in each light source section 20 in order to correspond to a multicolor light source. It is possible to dispose a plurality of LED chips of the same emission color or different emission colors in each light source unit 20, and two or three types of different emission colors can be provided in order to correspond to multi-coloring of a reading device or the like. It is also possible to repeatedly arrange the LED chips (preferably having an emission color selected from the colors corresponding to the three primary colors) and sequentially arrange them in the light source unit 20.

The plurality of light source sections 20 are arranged over the substantially entire length of the substrate 10 at intervals of, for example, 5.73 mm, and are provided with a plurality of elliptical light source sections 20a having an elliptical planar shape. And an outermost elliptical light source unit 20a located at both ends of the substrate 10 and a circular light source unit 20b arranged with a pitch of, for example, 5.5 mm and having a circular planar shape. ing. Board 1
When the resin 22 is molded, the insulating film on the zero surface is subjected to contour processing for defining the planar shape of the resin of the elliptical light source 20a and the circular light source 20b.

In each elliptical light source section 20a, even when the number of light source sections is small and the pitch thereof is long, the illuminance distribution is flattened by utilizing the light buffering (overlapping of light) of the adjacent light source sections. In addition, the major axis direction is arranged in the same direction as the longitudinal direction of the substrate 10 (the major axis may slightly intersect with the substrate longitudinal direction) so that the light buffering degree of the adjacent elliptical light source sections 20a is enhanced. Is configured. Therefore, the elliptical light source unit 2
As shown in FIG. 3, the resin 22a constituting 0a has a convex elliptical shape having a major axis length of 4 mm and a minor axis length of 3.4 mm and a maximum thickness of about 1 mm. Is configured. With the plane elliptical shape, the illuminance of the effective light source (irradiation) area can be kept within a prescribed range even if the pitch of the elliptical light source sections 20a is slightly long, and the number of elliptical light source sections 20a can be reduced. Can be reduced.

The circular light source portion 20b is provided in order to prevent a decrease in the illuminance distribution at the end portion of the light source (substrate) and increase the effective light source length.
As shown in FIG. 4, b has a diameter of 3.4 mm, for example.
And a convex lens shape having a maximum thickness of about 1 mm. In this way, the resin 22b has the same maximum thickness and the planar shape thereof is the elliptical light source unit 2.
Since it is made narrower than the resin 22a of 0a, the light emitting element 2
When the amount of light emitted from 1 is the same, the degree of converging of the light can be increased more than in the case of the elliptical light source unit 20a, and the illuminance at the end of the light source where the illuminance distribution is reduced is increased and the illuminance distribution becomes flat. The length of the region can be increased to the end of the light source to increase the ratio of the effective light source length to the total length of the light source. The circular light source unit 20b includes the light emitting element 21.
It suffices that the degree of condensing light emitted from the elliptical light source unit 20a can be increased, and the planar shape of the resin 22b is closer to a circular shape than the resin 22a of the elliptical light source unit 20a (for example, the long axis). Has a length of 3.5 to 3.6 m
m, a plane ellipse having a minor axis length of 3.4 mm). Also, the type of resin can be changed so as to increase the light condensing degree, but since the manufacturing process is complicated, the light condensing degree can be changed by changing the plane shape and thickness of the same resin. The variation is desirable in that the same manufacturing process can be used. In particular, if the thickness of the resin is made substantially the same and its planar shape is changed, the thickness of the light source can be made uniformly thin over the entire range. Therefore, it is preferable in terms of thinning compared to the case of changing the thickness.

As described above, the linear light source 1 includes the light source section 20.
Since the light-transmissive resin constituting the above is directly formed on the substrate 10, the structure can be simplified, and since the light source portions 20 are arranged apart from each other, distortion or warpage of the resin 22 due to thermal stress, etc. Without the deformation of
It is possible to prevent the deviation of the illuminance distribution. In addition, since the thickness of each light source unit 20 can be made extremely thin and approximately 1 mm, the linear light source 1 can be thinned.

With the above structure, the following characteristics were obtained. First, FIG. 5 shows cross-sectional illuminance distribution characteristics showing the spread of light along the cross-sectional direction of the light source. This optical characteristic is
The illuminance distribution is measured at a distance of 8 mm from the surface of the substrate 10 along a cross section orthogonal to the longitudinal direction of 0. The figure (a) is a characteristic when the said cross section passes through the light emitting element 21 of the elliptical light source part 22, and the figure (b) is,
This is a characteristic when the cross section passes between the elliptical light source portions 22. As is clear from this characteristic diagram, the elliptical light source unit 2
It can be seen that even if the pitch of 2 is somewhat long, the same illuminance is obtained on the light source unit 22 and between the light source units 22 by the light buffering function of the elliptical light source unit 22. In particular, since the lengths (widths) at which 80% illuminance can be obtained are both 5.6 mm, which is a predetermined value, even if the mounting accuracy of the substrate 10 is somewhat poor, a certain illuminance can be ensured on the illuminated portion. Can be given.

Next, FIG. 6 shows the illuminance distribution characteristic along the longitudinal direction of the light source (substrate). This optical characteristic is that each light source unit 2
The substrate 1 along the longitudinal direction of the substrate 10 so as to pass through 0.
The illuminance at a distance of 8 mm from the surface of 0 is measured, and the illuminance deviation obtained based on the measured illuminance is shown. As is clear from this characteristic diagram, the area within ± 10% of the illuminance deviation can realize 219 mm over almost the entire length of the light source. Therefore, the effective light source length can be set to 219 mm with respect to the total light source length of 227 mm, and the ratio of the effective light source length to the light source length can be increased.

[0022]

According to the present invention, since the light source portions are arranged apart from each other along the longitudinal direction of the substrate, the resin due to thermal stress such as when the translucent resin is continuous in the longitudinal direction of the substrate is provided. It is possible to reduce the variation in illuminance by almost eliminating the warp.

Further, in the plurality of light source sections, the light collecting degree of the resin forming the light source section located at the end of the substrate is higher than the light collecting degree of the resin forming the other light source sections, so that the illuminance at the light source end section is increased. It is possible to easily increase the effective light source length without changing the light emitting elements.

In the plurality of light source parts, the maximum thickness of the light-transmitting resin is made substantially constant, and the planar shape of the light-transmitting resin is the light source part at the end and the light source parts located inside thereof. The light condensing degree can be easily changed only by changing the planar shape of the resin, and the illuminance at the end of the light source can be easily changed without changing the light emitting element. Since the thickness of the light source can be made thin and substantially uniform, the light source can be made thin.

Further, the plurality of light source portions are formed into an elliptical light source portion in which the plane of the transparent resin forms an elliptical shape, and the plane of the transparent resin is circular or a circular shape closer to a circle than the elliptical shape. The circular light source part is arranged at the end of the light source, and the elliptical light source part can flatten the illuminance distribution by the light buffering (superposition of light) effect. The arrangement pitch of the parts can be lengthened to reduce the number of light source parts. In addition, the translucent resin's planar shape is changed to an ellipse or a circle, which has less unevenness in illuminance and makes it easier to obtain a stable resin shape, so resin molding can be performed easily and stably, and uniform optical characteristics can be achieved. Can be planned.

[Brief description of drawings]

FIG. 1 is a perspective view of a linear light source showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

3A and 3B show configuration examples of an elliptical light source unit, FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view.

FIG. 4 shows a configuration example of a circular light source section, (a) is a plan view,
(B) is a sectional view.

5A and 5B are cross-sectional illuminance distribution characteristic diagrams of a light source, where FIG. 5A is a distribution characteristic diagram on a light source section, and FIG.

FIG. 6 is a longitudinal illuminance distribution characteristic diagram of a light source.

[Explanation of symbols]

 1 linear light source 10 substrate 20 light source part 20a elliptical light source part 20b circular light source part 21 light emitting element 22 translucent resin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Yoshi ▼ Masayasu Ura 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A long substrate, a plurality of light source portions formed of a light emitting element disposed on the substrate and a translucent resin covering the light emitting element, the light source portion being arranged in a longitudinal direction of the substrate. A linear light source that is linearly arranged apart from each other along a line, wherein the plurality of light source units are configured such that the light condensing degree of the resin forming the light source unit located at the end of the substrate is equal to that of the resin forming the other light source units. A linear light source characterized by a higher light collection efficiency. 2. A plurality of linear substrates which are composed of a long substrate, a light emitting element arranged on the substrate, and a translucent resin covering the light emitting element and which are linearly arranged apart from each other along the longitudinal direction of the substrate. The plurality of light source units have a maximum thickness of the translucent resin substantially constant, and the planar shape of the translucent resin is located at the end light source unit and inside thereof. A linear light source that is different from the light source section. 3. A plurality of linear substrates which are composed of a long substrate, a light emitting element arranged on the substrate, and a translucent resin covering the light emitting element and which are linearly arranged apart from each other along the longitudinal direction of the substrate. A plurality of elliptical light source portions each having a light-transmitting resin plane formed into an elliptical shape, and the light-transmitting resin planes being circular or circular rather than the elliptical shape. A linear light source, characterized in that the linear light source is composed of a circular light source part having a close elliptical shape, and the circular light source part is arranged at an end of the light source.