JPH09230339A - Illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the irregularity of illumination with a simple structure and to improve brightness by uniform illumination by forming a reflection layer having a size smaller than the external form of the light guide plate and installing an area where the light made incident from the light source between the light source and the reflection layer is totally reflected by the light guide plate to be guided to the reflection layer. SOLUTION: The size of a white reflection layer 9 determined by the length D in the lengthwise direction and the length C in the widthwise direction is set so as to be the same as the lengths A, B in the lengthwise and widthwise directions which determine the display range of segment-displayed characters and symbols 11 or smaller than the outer-diameter area of the acrylic plate 8. The white reflection layer 9 is installed in the vicinity of the display range of characters and symbols 11 which are subjected to segment-display needing minimal illumination. By such configuration, an area totally reflected by the acrylic plate 8 between the light emitting section 7 and the white reflection layer 9 is formed, and thereby the light guided to the acrylic plate 8 is not reflected by its whole surface but reflected only in the range of the white reflection layer 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device such as a small electronic device, and more particularly to a lighting device for illuminating characters or symbols on a liquid crystal display such as a calculator or an electronic timepiece.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing an example of a conventional illumination device for a liquid crystal display, in which 1 is a light source such as an LED, 2 is a printed circuit board, 3 is acrylic which is a kind of translucent resin plate. The plate 4 is a reflecting surface provided on the surface of the printed board 2, and
Is a cutout provided in the acrylic plate, 6 is a Fresnel processed surface, 7
Is a light emitting portion of the light source 1. In the LED 1, the light emitting portion 7 is a notch portion 5 provided on both end surfaces of the acrylic plate 3 in the longitudinal direction.
Is provided on the printed circuit board 2 so as to be located at. The reflective surface 4 is provided on the surface of the printed circuit board 2 so as to be sandwiched between the LEDs 1 on both sides. The Fresnel processed surface 6 is formed on the side of the acrylic plate 3 that faces the reflective surface 4.

In the above-mentioned conventional illuminating device, the light indicated by the arrow a emitted from the light emitting portion 7 of the light source 1 is incident on the inside of the acrylic plate 3 from the end face of the notch 5, and a part of the light is Fresnel processed surface. A part of the other light is reflected by the Fresnel-processed surface 6 of the acrylic plate 3 and is reflected by the reflecting surface 4, and a liquid crystal display (not shown) arranged in front of the acrylic plate 3 is shown. No.) is illuminated from the back side.

[0004]

However, the conventional lighting device shown in FIG. 7 has a problem that the acrylic plate 3 needs to be processed to provide the Fresnel processed surface 6 and thus is expensive.

Further, since the amount of light emitted from the light source 1 becomes maximum in the direction of the arrow a which is the center of the directivity of the light source 1, the vicinity of the light source 1 of the acrylic plate 3 becomes the brightest, while the acrylic plate 3 The peripheral portions such as the corners of the above become dark, and therefore, the illumination of the peripheral portions such as the corners of the rectangular liquid crystal display becomes dark and there is a drawback that the illumination becomes uneven.

The present invention has been made in view of the above problems, and an object thereof is to reduce irradiation unevenness of illumination light for illuminating characters and symbols on a liquid crystal display or the like while having a simple structure. In addition, it is to provide a lighting device capable of providing uniform illumination light and further improving brightness.

[0007]

In order to solve the above-mentioned problems and to achieve the object, an illumination device of the present invention has the following constitution. That is, a light-transmitting light guide plate whose surface is mirror-finished is arranged on the back surface of the display unit, and a reflection layer that reflects light is formed on this light guide plate, so that the light incident from the light source is reflected by the reflection layer. A lighting device configured to emit light from the light guide plate to illuminate the display unit from the back surface, wherein the reflection layer is formed smaller than the outer shape of the light guide plate, and is provided between the light source and the reflection layer. An area is provided for totally reflecting the light incident from the light source by the light guide plate and guiding it to the reflective layer.

As described above, in the lighting device of the present invention, part of the light introduced into the light guide plate is directly reflected by the reflective layer, and part of the light is reflected by the surface of the light guide plate to the reflective layer. Since the light is guided, the incident light density per unit area of the reflective layer is increased, and bright reflected light is generated.

Further, since the reflection layer is formed so as to be substantially equal to or slightly larger than the display range of the display unit, the darkness at the peripheral portions such as the corners of the light guide plate is solved and the light guide plate is solved. Can be easily processed.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) First, a lighting device according to a first embodiment of the present invention will be described.

FIG. 1 is an exploded perspective view showing the structure of a lighting device according to a first embodiment of the present invention.

In FIG. 1, 8 is an acrylic plate as a kind of translucent resin plate, 9 is a white reflective layer, 10 is a liquid crystal display (transmissive type), 11 is a segmented character or symbol, and 12 is A heat seal made of a flexible material printed with a conductor, 13 is an external connection terminal, and 14 is a terminal connection pattern of the printed circuit board 2. The LED 1 is provided on the printed circuit board 2 in close contact with each end face of the acrylic plate 8 so that the light emitting unit 7 is located on both end faces of the acrylic plate 8 in the longitudinal direction, and all the light from the light emitting unit 7 is incident on the acrylic plate 8. It has become so. The reflecting surface 4 is formed on the surface of the printed circuit board 2 so as to be substantially the same as or slightly larger than the outer shape of the acrylic plate 8. The acrylic plate 8 is a rectangular flat plate that is arranged on the printed circuit board 2 and has a thickness such that the light emitting portion 7 is located substantially at the center of the acrylic plate 8 in the thickness direction. It is processed so as to be perpendicular to the substrate 2. In addition, the acrylic plate 8 has a structure shown in FIG.
The notch portion 5 and the Fresnel processed surface 6 shown in are not provided.
The other configurations are given the same reference numerals as the configurations described with reference to FIG. 7, and description thereof will be omitted.

Next, the principle of irradiation of illumination light by the illumination device of the first embodiment will be described. FIG. 2 is a partial cross-sectional view of the lighting device shown in FIG. 1 in an assembled state, and the liquid crystal display is not shown.

1 and 2, reference numeral 15 is a lead of the LED 1, and the LED 1 is soldered to the printed circuit board 2 at both ends of the acrylic plate 8 via the lead 15.
Arrows B, C, D, E, F, F, G, and J represent light rays emitted from the light emitting unit 7 serving as a light source.

The light emitted laterally from the light emitting portion 7 of the LED 1 enters inside from the end face in the longitudinal direction of the acrylic plate 8,
Proceed upward as indicated by arrow D, reflected on the surface of the acrylic plate 8 and proceeded downward, and then reflected upward by the white reflective layer 9 again and proceed as indicated by arrow D. A part of the light is reflected by the back surface of the acrylic plate 8 and travels upward, and a part of the light passes through the acrylic plate 8 and is reflected by the reflective surface 4 to travel in the direction of arrow E. Further, the light indicated by the arrow is directly reflected by the white reflective layer 9 to illuminate the display range of the character and the symbol 11 of the liquid crystal display 10 provided above the arrow together with the arrow from the back surface. In addition, as shown in FIG. 1, the light emitted from the light emitting portion 7 of the LED 1 and indicated by arrows C, C, and H parallel to the printed circuit board 2 is introduced into the acrylic plate 8 and is reflected on the end surface of the acrylic plate 8. The reflected light is reflected by the white reflective layer 9, and the display range of the characters and symbols 11 of the liquid crystal display 10 is illuminated in the same manner. Further, the reflection inside the acrylic plate 8 is not simple and is generally reflected mainly at the boundary surface with the air a plurality of times, and the light from the light emitting portion 7 of the LED 1 is emitted in all directions. Of.

In the structure described above, the size of the white reflective layer 9 determined by the length D in the longitudinal direction and the length C in the width direction is
Characters and symbols 11 that are set to be equal to the dimensions of lengths A and B in the longitudinal direction and width direction that determine the display range of the characters and symbols 11 or smaller than the outer diameter area of the acrylic plate 8 and require minimum illumination. The white reflective layer 9 is provided only near the display range. Further, with such a structure, a region that is totally reflected by the acrylic plate 8 is formed between the light emitting unit 7 and the white reflective layer 9, so that the light introduced into the acrylic plate 8 may not be totally reflected. However, since the light is reflected only in the range of the white reflective layer 9, the density of incident light per unit area is increased, and bright reflected light can be obtained.

(Second Embodiment) Next, a lighting device according to a second embodiment of the present invention will be described.

FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 showing the structure of the illuminating device of the second embodiment according to the present invention.

In FIG. 3, in the lighting device of the second embodiment, both longitudinal end faces of the acrylic plate 17 are inclined inward by an angle θ, and the acrylic plate 17 has a trapezoidal cross section in the longitudinal direction. There is. In addition, the LED 1 has its light emitting portion 7
In order to increase the amount of light that is incident on the white reflective layer 9 and is directly applied to the white reflective layer 9, the leads 15 of the LED 1 are attached at an angle θ so as to be in close contact with each end face so as to correspond to both end faces having an inclination angle θ. Soldered to the printed circuit board 2. The size of the white reflective layer 9 is the same as that of the first embodiment, as shown in FIG.
It is set to be equal to the display range of symbol 11 or smaller than the outer diameter area of the acrylic plate 8. The rest of the configuration is the same as that of the first embodiment, and therefore its explanation is omitted.

According to the second embodiment described above, in addition to the effects of the first embodiment, by increasing the amount of light that is incident from the light emitting section 7 of the LED 1 and is directly irradiated on the white reflective layer 9, The loss of light reflected in the acrylic plate 17 can be reduced.

(Third Embodiment) Next, an illumination device according to a third embodiment of the present invention will be described.

FIG. 4 is a perspective view showing the shape of the acrylic plate of the third embodiment. FIG. 5 is a partial cross-sectional view corresponding to FIG. 2, showing a configuration of a lighting device according to a third embodiment of the present invention.

In FIGS. 4 and 5, the lighting device of the third embodiment is an acrylic plate 18 which has longitudinal inclined portions 18a and 18f on its end faces in the longitudinal direction and partial inclined portions 18b, 18c on its end faces in the width direction. This is an example using the one in which 18d and 18e are formed. By using this acrylic plate 18, the light incident on the acrylic plate 18 and indicated by the arrow N parallel to the printed circuit board 2 is reflected by the longitudinal inclined portions 18a and 18f and the partial inclined portions 18c to 18e, so that the acrylic plate 18 is Can be reflected on the white reflective layer 9, and the amount of light reflected by the white reflective layer 9 can be increased. Since the configuration other than the above is the same as that of the first embodiment, the description thereof will be omitted.

According to the third embodiment described above, in addition to the effects of the first embodiment, by increasing the amount of light that is incident from the light emitting section 7 of the LED 1 and is applied to the white reflective layer 9, the acrylic resin can be obtained. The loss of light reflected in the plate 18 can be reduced.

(Fourth Embodiment) Next, an illumination device according to a fourth embodiment of the present invention will be described.

FIG. 6 is an exploded perspective view of a lighting device according to a fourth embodiment of the present invention.

In FIG. 6, the illumination device according to the fourth embodiment is determined by the length E in the longitudinal direction and the length F in the width direction of the white reflective layer 16 on the rear surface side facing the reflective surface 4 of the acrylic plate 8. The size to be displayed is set to be equal to or slightly larger than the dimensions of the lengths A and B in the longitudinal direction and the width direction that determine the display range of the characters and symbols 11, and the size of the display range of the characters and symbols 11 is approximately the same. By making the shape like a segment display, the total area of the white reflective layer 16 is reduced, the incident density per unit area is increased, and the brightness of the reflected light is increased. Since the configuration other than the above is the same as that of the first embodiment, the description thereof will be omitted.

According to the fourth embodiment described above, the density of incident light per unit area is higher than that of the first embodiment, and bright reflected light can be obtained.

The present invention can be applied to a modified or modified version of the above embodiment without departing from the spirit of the present invention.

For example, the configuration of the second or third embodiment may be added to the configuration of the fourth embodiment.

Further, Ls arranged to face each other
A plurality of sets of ED1 may be provided, or one or more ED1 may be provided only on one side of the reflecting surface 4.

Also, a small incandescent light bulb such as a wheat light bulb may be used instead of the LED 1.

[0034]

As described above, according to the present invention,
A light-transmitting light guide plate having a mirror-finished surface is disposed on the back surface of the display unit, and a reflecting layer that reflects light is formed on the light guide plate to reflect the light incident from the light source on the reflecting layer. When the light is emitted from the light guide plate to illuminate the display unit from the back surface, the reflection layer is formed smaller than the outer shape of the light guide plate, and the light incident from the light source is interposed between the light source and the reflection layer. By providing an area for totally reflecting the light to reach the reflective layer, the density of incident light to the reflective layer per unit area is increased and the brightness of the reflected light is increased. The required Fresnel surface is not necessary, and even with a simple structure, it is possible to reduce uneven irradiation of illumination light that illuminates characters and symbols on a liquid crystal display or the like, and to improve the uniformity of illumination light and the brightness.

[0035]

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the lighting device shown in FIG. 1 in an assembled state.

FIG. 3 is a partial cross-sectional view showing a configuration of a lighting device of a second embodiment according to the present invention and corresponding to FIG.

FIG. 4 is a perspective view showing a shape of an acrylic plate according to a third embodiment.

FIG. 5 is a partial sectional view corresponding to FIG. 2, showing a configuration of a lighting device of a third embodiment according to the present invention.

FIG. 6 is an exploded perspective view of a lighting device of a fourth embodiment according to the present invention.

FIG. 7 is a diagram showing an example of a conventional illumination device for a liquid crystal display.

[Explanation of symbols]

 1 LED 2 Printed Circuit Board 4 Reflective Surface 7 Light Emitting Section 8 Acrylic Plate 9 White Reflective Layer 10 Liquid Crystal Display (Transmissive) 11 Segment Displayed Characters and Symbols 15 Lead

Claims (9)

[Claims] 1. A light guide plate having a light-transmitting property, the surface of which is mirror-finished, is arranged on the back surface of a display section, and a reflection layer for reflecting the light is formed on the light guide plate to reflect the light incident from the light source. An illuminating device configured to reflect light from a layer and emit the light from the light guide plate to illuminate the display unit from the backside, wherein the reflective layer is formed smaller than the outer shape of the light guide plate,
An illumination device, wherein an area is provided between the light source and a reflective layer for totally reflecting the light incident from the light source by the light guide plate and guiding the light to the reflective layer. 2. The lighting device according to claim 1, wherein the reflective layer is formed to have substantially the same size as or slightly larger than the display range of characters and the like on the display section. 3. The lighting device according to claim 1, wherein the reflective layer is formed in a range substantially equivalent to a display range of characters and the like on the display section. 4. The lighting device according to claim 1, wherein the reflection layer is formed on the light guide plate by printing or attaching a tape. 5. The lighting device according to claim 1, wherein the light guide plate is made of resin, and the light source is provided in close contact with the light guide plate in the vicinity of an end face in the thickness direction. 6. The lighting device according to claim 5, wherein at least one of the light sources is provided on each end surface of the light guide plate facing each other. 7. The light emitting device according to claim 6, wherein the end face and the light source are inclined toward the reflection layer side by a predetermined angle so that a part of the light incident from the light source directly strikes the reflection layer. Lighting equipment. 8. The illumination according to claim 5, wherein an inclined portion is provided on the end face, and light parallel to the surface of the light guide plate is reflected by the inclined portion and guided to the reflective layer. apparatus. 9. The lighting device according to claim 1, wherein the display unit is a liquid crystal display device, and the light source is an LED lamp.