JPH097414A - Linear light source - Google Patents

Abstract

PURPOSE: To uniformize illuminance of a light emitting surface by oppositely holding a pair of light emitting elements on both ends of a bar-shaped light conductive plate forming a pair of inclined faces having an upward inclination toward the center from both end parts on a light reflecting surface. CONSTITUTION: When light emitting elements 2 and 2 are made to emit the light by current-conduction, the light generated from an LED chip 23 is outputted as the light having directivity in the lengthwise direction of the light emitting elements 2 by a reflecting effect of a receiving stand 24 and a condensing effect of a lens shape of a light emitting part 22. Though this light is made incident on a convex lens-shaped light incident surface 13 of a light conductive plate 1, since the optical axis of a light projecting surface of the light emitting elements 2 and the light incident surface 13 of the light conductive plate 1 is positioned so as to coincide with the lengthwise direction of the light conductive plate 1 by an element holding member 3, the light of the light emitting elements 2 can be efficiently conducted to the light conductive plate 1. The light incident on the light conductive plate 1 mainly reaches an inclined face 12b of a light reflecting surface 12, and is reflected here, and is almost uniformly emitted upward from a light emitting surface 11.

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 for illuminating using a rod-shaped light guide and light emitting elements arranged at both ends thereof.

[0002]

2. Description of the Related Art A conventional linear light source generally has an L on a substrate.
A plurality of light-emitting elements such as EDs are arranged in a line and light is output directly above (Japanese Patent Laid-Open No. 60-2306).
No. 25). With such a configuration, a considerable number of LEDs are required for the required illumination length, there is a problem of large power consumption and heat generation, and the brightness of the LED element, VF to suppress the deviation of the light output. There was a problem that it was necessary to manage each of these individually.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel linear light source using a small number of light emitting elements in consideration of the above-mentioned problems of the conventional linear light source. With this new linear light source, the main problem is to reduce the number of light emitting elements, simplify the configuration, and improve the assembly workability while maintaining a predetermined function, and other problems will be described later. To clarify.

[0004]

According to the present invention, there is provided a light emitting surface along a longitudinal direction and a light reflecting surface facing the light emitting surface, and the light reflecting surface is inclined upward from both ends toward the center. A rod-shaped light guide plate having a pair of inclined surfaces, a pair of light emitting elements held face-to-face with light incident surfaces located at both ends of the light guide plate, and a light exit surface of the light guide plate exposed to expose the light guide plate. An elongated case-shaped light guide plate holding member having a H-shaped or U-shaped cross section that is accommodated and held over substantially the entire length is provided.

According to the present invention, there is provided a rod-shaped light guide plate having a light exit surface and a light reflection surface facing the light exit surface along the longitudinal direction and a light entrance surface at an end thereof, and the light entrance of the light guide plate. A light emitting element held by an element holding member so that a convex light projecting surface faces the surface, and the light incident surface of the light guide plate has a radius of curvature equivalent to the radius of curvature of the light projecting surface of the light emitting element. The light emitting element is formed in a convex shape, and the light emitting element is attached to the light guide plate by the element holding member so that the optical axis of the light emitting element substantially coincides with the optical axis of the light incident surface.

According to the present invention, a rod-shaped light guide plate having a light exit surface and a light reflection surface facing the light exit surface, and a pair of light emitting elements arranged facing the light entrance surfaces located at both ends of the light guide plate, A light guide plate holding member for holding the light guide plate, wherein the light guide plate has a pair of inclined surfaces having an upward inclination toward the center on the light reflecting surface, and thus the thickness becomes thinner toward the center. The light guide plate holding member is a case-like member having a predetermined rigidity that covers the light reflection surface of the light guide plate and the left and right side faces on both sides thereof. In addition to the above structure, a locking portion that engages with the engaging portion of the light guide plate is formed, and the guiding portion is formed by engaging the engaging portion of the light guide plate with the engaging portion of the light guide plate holding member. The light plate is held by the light guide plate holding member. It is.

[0007]

According to the present invention, a pair of light emitting elements are held face-to-face on the light incident surfaces located at both ends of a rod-shaped light guide plate in which a pair of inclined surfaces having an upward inclination from the both ends toward the center are formed on the light reflecting surface. Therefore, the light of the pair of light emitting elements can be reflected by the pair of inclined surfaces to make the illuminance on the light emitting surface uniform. Furthermore, the presence of the pair of inclined surfaces makes the central portion of the rod-shaped light guide plate thin and reduces its strength, but the cross section for accommodating and holding this light guide plate over almost its entire length is an elongated case shape having an H shape or a U shape. Since it is equipped with the light guide plate holding member, it is possible to surely reinforce the light guide plate,
It is possible to suppress bending and deformation of the light guide plate in the vertical and horizontal directions.

According to the present invention, the light incident surface of the light guide plate is formed in a convex shape having a radius of curvature equivalent to the radius of curvature of the light emitting surface of the light emitting element, and the optical axis of the light emitting element is the optical axis of the light incident surface. Since the light emitting element is attached to the light guide plate by the element holding member so as to substantially match with, the light directivity of the light emitting element can be enhanced by the convex light incident surface of the light guide plate and the light emitting element can be provided by the element holding member. The optical axes of the light guide plate and the light guide plate can be aligned with each other, and the light incident on the rod-shaped light guide plate can be efficiently and reliably guided to the central portion thereof.

Further, according to the present invention, a light guide plate holding member for holding a rod-shaped light guide plate is provided, and the light guide plate has a structure in which the wall thickness decreases toward the center and engaging portions are formed on the left and right side surfaces. The light guide plate holding member is composed of a case-like member having a predetermined rigidity that covers the light reflection surface of the light guide plate and the left and right side surfaces on both sides thereof, and is also engaged with the engaging portion of the light guide plate. The light guide plate is configured to be formed by forming a portion, and the light guide plate is held by the light guide plate holding member by engaging the engaging portion of the light guide plate with the locking portion of the light guide plate holding member. Can be easily and surely reinforced by the light guide plate holding member.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a linear light source, and FIG. 2 is a plan view thereof. In each drawing, the dimension in the longitudinal direction is reduced to about 1/2 and the dimension in the lateral direction is enlarged to about 2 times. Shows. FIG. 3 is an enlarged sectional view taken along line AA of FIG. In the figure, 1 is a rod-shaped light guide plate, 2 and 2 are light emitting elements, 3 and 3 are holding members for light emitting elements, and 4 is a holding member for the light guide plate 1.

The light guide plate 1 is made of a transparent resin such as acrylic or polycarbonate having a light transmitting property. For example, the maximum external dimension is about 5 × 5 mm and the length is 300 mm.
It is composed of front and rear bars. The upper surface along the longitudinal direction of the light guide plate 1 is a light emitting surface 11, and the lower surface facing the light emitting surface 11 is a light reflecting surface 12. The light emitting surface 11 and the light reflecting surface 1
The two end faces located at both ends of 2 are a pair of light incident faces 13 and 13
And The surfaces located along the light emitting surface 11 and the light reflecting surface 12 are left and right side surfaces 14, 14.

The light emitting surface 11 may have a flat surface or a semi-cylindrical shape. However, since the light reflecting surface 12 reflects the light in a planar manner, a semi-cylindrical lens is not very effective, and thus the structure is formed. It is preferable to have a planar shape that can be simplified.

The light reflecting surface 12 is a light incident surface 13, 13
In order to prevent the illuminance of both end portions of the light guide plate 1 near the light guide plate 1 from increasing due to light reflection, a pair of flat surfaces 12a, 12a substantially parallel to the light emitting surface 11 are formed at both end portions of the light guide plate 1. In order to prevent the illuminance of the central portion from weakening as the distance from the light incident surfaces 13 and 13 increases, a pair of inclined surfaces 12 having an upward inclination from both ends toward the center.
b and 12b are formed in the central portion. By forming the light guide plate 1 in this way, the light guide plate 1 has a shape in which the tips of the two wedges are butted against each other, and the wall thickness decreases toward the center. Then, at least the inclined surfaces 12b, 12b are subjected to light reflection processing. As the light reflection processing, a plurality of notches (or grooves) are formed in a direction orthogonal to the longitudinal direction of the light guide plate 1, a coating material containing a light reflecting agent is applied, or a white ink or the like having a good light reflecting property. It can be performed by applying a material, and the depth, pitch, angle, etc. of the notches are gradually changed or the density of the light reflecting agent is gradually changed so that the light reflectance increases toward the center. Alternatively, the density of white ink or the like or the print pattern can be gradually changed. The light reflection processing is performed by the pair of flat surfaces 12a, 12a as necessary.
It can also be applied to

The light incident surfaces 13 and 13 are emitted from a light emitting element whose light intensity is weak and light directivity is not so high.
In order to enhance the directivity of the light incident on the light guide plate 1, the light guide plate 1 is formed in a convex lens shape having an optical axis in the same direction as the longitudinal direction. The radius of curvature r of this convex lens portion is such that the incident light does not reach the flat portion 12a as much as possible and the inclined surface 12
It is set to about 2 to 2.5 mm so as to reach b. A pair of engagement protrusions 15, 15 for engaging with the element holding member 3 are provided on upper and lower surfaces of the light guide plate 1 near the light incident surfaces 13, 13. The part is integrally formed.

Further, the left and right side surfaces 14 and 14 located near the light emitting surfaces 11 and 11 are engaged with the light guide plate holding member 4, so that a plurality of engaging projections 16 formed at predetermined intervals are provided.
The engaging portion composed of 16 is integrally formed as shown in FIG.

For the light emitting elements 2 and 2, for example, it is preferable to employ a semiconductor laser having a high directivity and a large optical output, but since it is expensive and costly, the lead wire 21 is an inexpensive and easily available light emitting element. LED (light emitting diode) having a light emitting portion 22 resin-molded at the tip of the
Has been adopted. This light emitting element 2 has a predetermined lead wire 2
One or a plurality of LED chips 23 are mounted on the tip of one, and the other lead wire 21 and this chip 23 are connected by wire bonding, and these are molded by a transparent resin. . At the tip of the lead wire 21 on which the LED chip 23 is placed, a bowl-shaped cradle 24 having a good light-reflecting property is integrally formed with its opening facing the tip. It is configured such that the light of 23 is condensed and the light of which the directivity is enhanced in the light emitting direction of the light emitting element 2 is emitted. The light projecting surface at the tip of the light emitting unit 22 is formed in a convex lens shape in order to enhance the light collecting property. This convex lens portion is adjusted so that its optical axis is in the same direction as the longitudinal direction of the light emitting element 2, and its radius of curvature r
Is the same as or slightly larger than the radius of curvature r of the light incident surface 13 so that the optical axis can be easily aligned with the light incident surface 13 of the light guide plate 1 and the light directivity inside the light guide plate 1 can be enhanced. It is set to around 2.5 mm. As described above, the light emitting elements 2 and 2 use LEDs that are inexpensive and easily available. However, if a semiconductor laser having a good light directivity and a large optical output is easily available, a semiconductor laser is used. It can also be adopted.

The element holding member 3 is the light emitting portion 2 of the light emitting element 2.
It is made of a white resin having a good light reflectivity, which is formed in a cylindrical shape longer than the length of the light emitting portion 22 so that the light guide plate 1 is positioned and accommodated and held face-to-face at both ends of the light guide plate 1. The inner shape of the element holding member 3 in the vicinity of the one end opening is formed so as to substantially match the outer shape of the end portion of the light guide plate 1 in order to ensure the attachment to the end portion of the light guide plate 1. In order to easily attach to the end of the light guide plate 1 near the opening, it is engaged with the engaging protrusions 15 and 15 of the light guide plate 2
Locking portions composed of one locking hole 31, 31 are formed in a pair in the vertical direction, and a hole for penetrating the lead wire 21 of the light emitting element 2 is formed in the other end opening.

The light guide plate holding member 4 reinforces the strength of the rod-shaped light guide plate 1 having a thin central portion, and reflects the light leaking from the light guide plate 1 to a surface other than the light emitting surface 11, thereby causing a loss of light. It is provided mainly for the purpose of preventing the above, and also has a structure that allows the light guide plate 1 to be housed and fixed easily and reliably. That is, the light guide plate holding member 4 is made of a white resin having good light reflectivity, and is formed on the left and right side surfaces 14, 1 of the light guide plate 1.
4 and the left and right side walls 41, 41 covering the light reflecting surface 12 and the bottom wall 42
Is formed in an elongated case shape having a predetermined rigidity as a whole and having an H-shape (area of the inclined surface 12b) or U-shape (area of the flat surface 12a) in cross section. Is also configured with a slightly shorter length. Left and right side walls 41, 4
1 is set to a length such that the upper end portion thereof projects slightly above the light emitting surface 11 of the light guide plate 1 in order to prevent the spread of light emitted from the light emitting surface when the light guide plate 1 is held. In addition, a plurality of locking holes 43, 43 forming a locking portion that engages with the engaging portions formed on the left and right side surfaces 14, 14 of the light guide plate 1 are provided at a position slightly above the center thereof at predetermined intervals. Has been formed. The bottom wall 42 is formed so as to face the light reflection surface 12 of the light guide plate 1, and has a pair of flat surfaces at both ends, like the light reflection surface 12 of the light guide plate 1. And has a pair of inclined surfaces having an upward inclination.

Next, the assembly of the linear light source will be described.
First, in the light guide plate 1, the light reflection surface 12 thereof has the light guide plate holding member 4.
The light guide plate 1 is housed and mounted in the light guide plate holding member 4 by being pushed in from above until it comes into contact with the bottom wall 42 of the. At this time, the engaging projections 1 provided on the left and right side surfaces 14, 14 of the light guide plate 1
6 and 16 are fitted into the locking holes 43, 43 provided in the left and right side walls 41, 41 of the light guide plate holding member 4 to form the light guide plate 1.
The light guide plate 1 and the light guide plate holding member 4 are integrated, and the light guide plate holding member 4 can reinforce the light guide plate 1 having a thin center and low strength. In particular, the left and right side walls 41, 41 and the bottom wall 42 of the light guide plate holding member 4 can suppress the bending and deformation of the light guide plate 1 in the vertical and horizontal directions.

Subsequently, the light emitting portion 22 of each light emitting element 2 is guided into the element holding member 3 so that the lead wire 21 of each light emitting element 2 is inserted from one end opening of the element holding member 3 and projected from the other end opening. . Then, the light projecting surface of the light emitting element 2 is seen at the one end opening of the element holding member 3, and the locking holes 31, 31 are formed.
Position and fix it so that it is located inward. Then, each element holding member 3 holding the light emitting element 2 is mounted on the light guide plate 1 so that the end portion of the light guide plate 1 is fitted into the opening at one end thereof. At this time, the upper and lower engaging holes 3 of the element holding member 3
The engaging protrusions 15 and 15 of the light guide plate 1 are fitted to the pins 1 and 31, respectively. By this fitting, the element holding member 3 and the light guide plate 1 are prevented from coming off, and the optical axis of the light emitting portion of the light emitting element 2 held by the element holding member 3 and the optical axis of the light incident surface 13 of the light guide plate 1 are aligned. The light guide plate 1 is positioned and mounted so as to coincide with an axis passing through substantially the center of the light guide plate 1 in the longitudinal direction. In this way, since the pair of light emitting elements 2 and 2 are positioned and attached to both ends of the light guide plate 1 by the element holding members 3 and 3, the light of each light emitting element 2 is centered along the longitudinal direction of the light guide plate 1. It is possible to reliably guide to the department.

The linear light source configured as described above is connected to a lead wire 21 in a predetermined manner, and for example, the light guide plate holding member 4 is attached to a predetermined mounting surface with an adhesive such as a double-sided tape, so that a predetermined device is provided. Be attached to. Then, when the light emitting elements 2 and 2 are made to emit light by energization, the light generated from the chip 23 is reflected by the pedestal 24 and the light emitting portion 22.
Due to the condensing effect of the lens shape, the light is emitted as light having directivity in the longitudinal direction of the light emitting element 2. This light is
The light is incident on the convex lens-shaped light incident surface 13 of the light guide plate 1, but the light projecting surface of the light emitting element 2 and the light axis of the light incident surface 13 of the light guide plate 1 are aligned with the longitudinal direction of the light guide plate 1 by the element holding member 3. Since the positioning is performed as described above, the light of the light emitting element 2 can be efficiently guided to the light guide plate 1. Further, since the light projecting surface of the light emitting element 2 and the convex lens-shaped portion of the light incident surface 13 of the light guide plate 1 are set to have substantially the same radius of curvature, optical axis alignment becomes easy. The light incident on the light guide plate 1 receives the light incident surface 13
The convex surface of the light-reflecting surface 12 mainly forms the inclined surface 12
It reaches b, is reflected here, and is emitted substantially uniformly upward from the light emitting surface 11. The light emitted from the light guide plate 1 has the right and left side surfaces 41 higher than the light emitting surface 11 of the light guide plate holding member 4,
The presence of 41 prevents the light guide plate 1 from spreading in the lateral direction.

The linear light source is the light guide plate 1 as described above.
Since the light emitting element 2, the element holding member 3, and the light guide plate holding member 4 are assembled by utilizing the engagement by the engaging projections and the engaging holes, the disassembling and assembling at the time of repair or inspection work can be easily performed. .

[0023]

According to the present invention, a pair of light emitting elements are provided on the light incident surfaces located at both ends of a rod-shaped light guide plate in which a pair of inclined surfaces having an upward inclination from both ends toward the center are formed on the light reflecting surface. Since they are held face-to-face, the light of the pair of light emitting elements can be reflected by the pair of inclined surfaces to make the illuminance on the light emitting surface uniform. Furthermore, the presence of the pair of inclined surfaces makes the central portion of the rod-shaped light guide plate thin and reduces its strength, but the cross section for accommodating and holding this light guide plate over almost its entire length is an elongated case shape having an H shape or a U shape. Since the above-mentioned light guide plate holding member is provided, the light guide plate can be reliably reinforced, and bending and deformation in the vertical and horizontal directions of the light guide plate can be suppressed.

According to the present invention, the light incident surface of the light guide plate is formed in a convex shape having a radius of curvature equivalent to that of the light projecting surface of the light emitting element, and the optical axis of the light emitting element is the optical axis of the light incident surface. Since the light emitting element is attached to the light guide plate by the element holding member so as to substantially match with, the light directivity of the light emitted from the light emitting element can be enhanced by the convex light incident surface of the light guide plate, and The holding member can match the optical axes of the light emitting element and the light guide plate, and the light incident on the rod-shaped light guide plate can be efficiently and reliably guided to the central portion thereof.

Further, according to the present invention, a light guide plate holding member for holding a rod-shaped light guide plate is provided, and the light guide plate has a structure in which the wall thickness becomes thinner toward the center and engaging portions are formed on the left and right side surfaces. The light guide plate holding member is composed of a case-like member having a predetermined rigidity that covers the light reflection surface of the light guide plate and the left and right side surfaces on both sides thereof, and is also engaged with the engaging portion of the light guide plate. The light guide plate is configured to be formed by forming a portion, and the light guide plate is held by the light guide plate holding member by engaging the engaging portion of the light guide plate with the locking portion of the light guide plate holding member. Can be easily and surely reinforced by the light guide plate holding member.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a linear light source of the present invention in which the dimension in the longitudinal direction is reduced and the dimension in the lateral direction is enlarged.

FIG. 2 is a plan view showing an embodiment of the linear light source of the present invention in which the dimension in the longitudinal direction is reduced and the dimension in the lateral direction is enlarged.

FIG. 3 is an enlarged sectional view taken along line AA of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 11 Light emitting surface 12 Light reflecting surface 12a Flat surface 12b Inclined surface 13 Light incident surface 15 Engagement protrusion 2 Light emitting element 21 Lead wire 22 Light emitting part 3 Element holding member 31 Locking hole 4 Light guide plate holding member 43 Locking Hole

Front page continued (72) Inventor ▲ Yoshi ▼ Masayasu Ura 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A pair of inclined surfaces having a light emitting surface along a longitudinal direction and a light reflecting surface facing the light emitting surface, and the light reflecting surface having an upward inclination from both ends toward the center. A rod-shaped light guide plate, a pair of light emitting elements facing each other at light incident surfaces located at both ends of the light guide plate, and a cross section for exposing the light exit surface of the light guide plate to accommodate and hold the light guide plate over substantially the entire length thereof. Is a slender case-shaped light guide plate holding member having an H shape or a U shape, and a linear light source. 2. A rod-shaped light guide plate having a light exit surface and a light reflection surface facing the light exit surface along the longitudinal direction, and a light entrance surface at an end, and the light entrance surface of the light guide plate. A light-emitting element held by an element holding member so that the convex light-projecting surfaces face each other, and the light-incident surface of the light guide plate has a radius of curvature equivalent to the radius of curvature of the light-projecting surface of the light-emitting element. A linear light source, which is formed into a shape and is attached to the light guide plate by the element holding member so that the optical axis of the light emitting element substantially coincides with the optical axis of the light incident surface. 3. A rod-shaped light guide plate having a light exit surface and a light reflection surface facing the light exit surface, a pair of light emitting elements arranged facing the light entrance surfaces located at both ends of the light guide plate, and the light guide element. A light guide plate holding member for holding a light plate, wherein the light guide plate has a structure in which the light reflection surface is formed with a pair of inclined surfaces having an upward inclination toward the center, whereby the wall thickness decreases toward the center. In addition, the left and right side surfaces are formed with engaging portions, and the light guide plate holding member is formed of a case-shaped member having a predetermined rigidity that covers the light reflection surface of the light guide plate and the left and right side surfaces on both sides thereof. At the same time, a locking portion that engages with the engaging portion of the light guide plate is formed, and the light guiding plate is fixed by engaging the engaging portion of the light guide plate with the engaging portion of the light guide plate holding member. It is configured to be held by the light guide plate holding member, Linear light source.