JPH10334718A - Plane luminous device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plane luminous device, which is concerned with a plane lighting device using a light emitting diode used for a liquid crystal back light, lighting type switch or display and which is specially and relatively easy to form and stable in luminous characteristics. SOLUTION: This plane luminous device has an LED luminous body which is electrically connected to an LED chip 102 placed on the inside bottom of an insulation resin case 101 having an opening at front and which has a lead frame 103 extending outside from the inside of insulation resin case 101, and has a light guide plate 105 which is formed out of a plate body approximate flat and translucent and on which light can be incident from the LED luminous body through an end face of the plate body. Particularly, the lead frame 103 for the LED luminous body is an elastic metal body, and the end part extending outward is shaped like a hook and fittingly engaged with notches provide on both the end parts of the light guide plate 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light emitting device used for a liquid crystal backlight, an illuminated switch, various display devices, etc., and more particularly to a planar light emitting device for transmitting light from an LED chip through a light guide plate. The present invention relates to a planar light emitting device that emits light.

[0002]

2. Description of the Related Art Today, liquid crystal displays have made remarkable progress because of their small driving power and small size as display devices. In a liquid crystal display, the liquid crystal device itself does not emit light. For this reason, the backlight is used so that it can be seen even in the dark. As the backlight, a cold cathode lamp, an LED lamp, or the like is used. A cold cathode lamp or an LED lamp (hereinafter also referred to as a light emitting diode) is a point light source or a line light source, and thus is usually formed as a surface light emitting device by using a light guide plate.

In particular, a surface light emitting device using an LED lamp does not generate noise since the driving power can be driven by DC power. Therefore, malfunction does not occur in precision equipment and various sensors due to noise. In addition, attention has been paid to low power consumption and miniaturization.

In a planar light emitting device using an LED lamp, light from an LED lamp is introduced from an end face corresponding to a thickness direction of a light guide plate, and light is extracted from a surface (front surface) direction of the light guide plate to form a planar light emitting device. is there. The thickness of the light guide plate is usually 2 to 5 mm
It is adjusted to be as thin as possible, and the LED lamp introduces light into the light guide plate by being embedded or adhered to the end face of the thin light guide plate. While the light introduced into the light guide plate is totally reflected on the surface, a part of the light is radiated from the front to the outside to form a planar light emitting device. In addition, the light emitted from the light guide plate is made uniform by providing innumerable irregularities in a desired pattern on the surface of the light guide plate, or applying a pigment or the like on the surface of the light guide plate in a desired pattern.

[0005] The light guide plate and the LED lamp can be connected to each other by connecting a shell-type light emitting diode to a housing surrounding the light guide plate by sandwiching it. A surface light emitting device using such a shell-type light emitting diode can be formed relatively easily.

[0006]

However, there is a problem that the non-light emitting portion is large and the planar light emitting device becomes large. In particular, as devices to be used such as notebook personal computers and mobile phones have become smaller and thinner, further reduction in the size of the planar light emitting device itself has become increasingly difficult.

On the other hand, as a planar light emitting device which can be reduced in size, there is a device using a chip type LED as shown in FIG. As a structure of the chip type LED, a lead frame 403 extending to the outside is provided on an inner bottom surface of a reflection case 401 having an open front surface. Lead frame 103
The LED chip 402 is die-bonded above. By fitting such a chip type LED into the fitting groove of the light guide plate 405, a planar light emitting device can be configured.

However, in the structure in which the chip type LED is dropped into the groove of the light guide plate 405, it is necessary to accurately guide the chip type LED into the fitting groove of the light guide plate and insert and fit it when assembling the chip type LED. There is a problem that it is difficult to attach. If the groove is made large to facilitate the assembly, it is difficult for the light emitting end face of the chip type LED and the light incident end face of the light guide plate to adhere to each other. Therefore, chip type LE
Light leakage between the end face of D and the end face of the light guide plate increases. Further, in today's world where stable light emission characteristics are required even in various use environments accompanying the expansion of use applications, the above configuration is not sufficient and further improvement is required.

[0009]

A planar light emitting device according to the present invention is electrically connected to an LED chip disposed on an inner bottom surface of an insulating resin case having an open front surface, and is provided inside the insulating resin case. An LED light-emitting body having a metal lead frame extending from the outside to a light guide plate formed of a substantially plate-shaped and light-transmitting plate to allow light from the LED light-emitting body to enter through an end surface of the plate. Have.
In particular, the lead frame of the LED luminous body is an elastic metal body, and the end extended to the outside has a hook shape, and the hook shape is fitted and locked with the cutouts provided at both ends of the light guide plate.

A planar light emitting device according to a second aspect of the present invention includes a plurality of insulating resin cases each having an LED chip disposed therein, and the respective insulating resin cases are connected by a lead frame. LED light emitter.

In the planar light emitting device according to a third aspect of the present invention, the lead frame of the LED light emitting body is an elastic metal body. Further, the end of the lead frame extending to the outside and the light guide plate are locked. Furthermore, this is a planar light emitting device in which the LED light emitter is pressed against the light guide plate by the elasticity of the lead frame.

[0012]

According to the present invention, the elasticity of the lead frame is
The ED light emitter and the light guide plate are fixedly locked. This allows for downsizing and relatively easy assembly. Further, the light emitting surface of the LED light emitter is constantly pressed against the end surface of the light guide plate by utilizing the elastic force of the lead frame. Even if thermal stress is generated due to driving, a certain degree of close contact is maintained. Therefore, it is possible to obtain a stable light output with high luminance without emission unevenness.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention
It has been found that the LED light emitter using a specific lead frame can be fixed and locked relatively easily and that the light emission luminance can be stabilized regardless of the use environment, and the present invention has been accomplished.

That is, in the present invention, a lead frame required for a light emitting diode as an LED light emitting body is extended and used for fixing and locking to a light guide plate. In particular, by utilizing the elasticity of the lead frame for close contact with the light guide plate, the LED light emitter and the light guide plate can be pressed relatively easily. Also,
Although the cause of the stabilization of the light-emitting characteristics by the configuration of the present invention is not clear, it is considered that the surface light-emitting body itself tends to be distorted when heated or cooled with use, and light leakage tends to be larger. . According to the present invention, since the LED luminous body is pressed against the light guide plate by the elastic force of the lead frame, the LED luminous body can be always in close contact even when vibration or temperature change occurs. It is considered that the brightness can be maintained. Hereinafter, the present invention will be described in detail. FIG. 3 is a perspective view of the planar light emitting device of the present invention.
In the LED light emitter 301, an LED chip (not shown) is disposed inside a case formed of an insulating resin. LE
The D chip is electrically connected to a lead frame 303 extending from the inside of the case to the outside. The end of the lead frame 303 extending to the outside has a hook-shaped portion. The hook portion is formed by folding the lead frame. On the other hand, the light guide plate 305 is formed in a flat plate shape having a substantially rectangular flat surface. Notches 325 are provided at both ends of the light guide plate to be fitted with the LED light emitter 301. The notches 325 are provided at four places on the light guide plate 305 so that two LED light emitters 301 can be arranged facing each other. The notch 325 and the hook of the LED light emitting body 301 have a shape that can be easily fitted by being fitted. The light guide plate 305 has a reflecting plate 315 except for a rear surface and an end surface connected to the LED light emitter so as to emit light in a planar shape.
Is attached. Thus, the planar light emitting device can be formed with a relatively simple configuration. Further, a planar light emitting device without uneven brightness can be obtained. Hereinafter, the configuration of the present invention will be described in detail.

(Insulating Resin Case 101) The insulating resin case 101 has a part of a lead frame inside an insulating resin having an open front surface, and has an LED chip 102 disposed on an inner bottom surface of the case. Is what you can do. The case has a concave portion, and the lead frame surfaces 103 and 113 on the inner bottom surface of the concave portion are exposed. Each electrode of the LED chip 102 and the exposed lead frame surface are made of gold,
Each of them can be electrically connected using a metal wire such as copper or a conductive paste containing a conductive filler such as Ag, Cu or carbon. After the LED chip 102 is mounted, the LED
In order to protect the chip 102, the chip 102 can be sealed with a light-transmitting sealing material such as a silicone resin or an epoxy resin.

It is preferable that the periphery of the external terminals 114 be made of a high heat resistant resin. By using a high heat-resistant resin, when the LED luminous body is soldered to an external substrate or the like, it is possible to block the transmission of heat during soldering from the external terminal to the diffusion light guide plate having a relatively low melting point. The light guide plate 105 is prevented from being melted or thermally deformed by heat.

As a material used for such an insulating resin case, a white insulating resin such as a liquid crystal polymer and PBT is preferably used. The insulating resin case can be formed relatively easily by insert molding or the like.

The LED luminous body is made of an insulating resin case 101.
Can be divided into a plurality of parts and combined by the lead frame 113. That is, the presence of the portion where the lead frame 113 is exposed between the insulating resin cases 101 can further increase the elastic force. Therefore, the LED luminous body can be efficiently pushed onto the light guide plate 105. Further, when there are a plurality of insulating resin cases 101 constituting the LED light-emitting body, a supporting member and a molded part 111 for an extraction electrode can be formed between the cases. The use of the supporting member and the molded portion 111 enables uniform light to be obtained even in a relatively large area planar light emitting device. Such a supporting member and a molded portion for a take-out electrode can be similarly formed using a white heat-resistant insulating resin such as a liquid crystal polymer or PBT, which is the same material as the insulating resin case.

(Lead Frames 103 and 113) The lead frame 103 can supply electric power to the LED chip 102 from the outside. In particular, in the present invention, the lead frame 103 is an elastic metal body, and also functions as a means for enabling the LED light-emitting body to be always press-fitted to the light guide plate 105 and locking it. For this reason, it is preferable that the material has excellent electrical conductivity and good elasticity. Further, the lead frame 103 can also function as a reflector for efficiently introducing the light emitted from the LED chip 102 into the light guide plate 105.

As a specific material for such a lead frame, a material such as copper, iron or phosphor bronze is preferable. In consideration of connection such as utilizing a bonding wire or reflected light of an LED chip, a wire plated with a noble metal such as gold or silver is more preferably used.

(Hook section 104) The hook section 104
It is used for fixing and locking to the light guide plate 105 using the lead frame 103 of the LED light emitter. Hook portion 104 formed at the end of lead frame 103
Any shape can be used as long as it can be fixed and locked by fitting the notch 325 of the light guide plate 105, and the end of the lead frame 103 is bent in a U-shape. Alternatively, it can take various forms as desired, such as forming a projection by driving. Further, the shape of the lead frame itself can take various forms such as a bow shape or a step shape. In any case, it is preferable that the insulating resin case 101, the molded part 111, and the like always have such a shape that pressure is applied to the end surface of the light guide plate 105.

(LED Chip 102) LED Chip 10
As for 2, various ones can be mentioned as required, such as emission color and use. LED chip 102 capable of emitting red or infrared light
As GaP, GaAs, GaAlAs, GaAs
An example in which a P, GaInAlP semiconductor is used for a light emitting layer is given. LED chips capable of emitting green or blue light include InN, AlN, GaN, GaAlN, and IN.
Those using nGaN or InGaAlN for the light emitting layer are preferably mentioned. As a semiconductor structure, a MIS junction,
Various emission wavelengths can be selected depending on the material of the semiconductor layer such as a homo structure, a hetero structure, and a double hetero structure having a PN junction and the degree of mixed crystal thereof. Also, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed as a thin film in which a quantum effect occurs can be used.

The LED chip 102 can be selected and used in various ways according to the emission color and luminance. When it is desired to emit light from the planar light emitting device with higher luminance, two or more LED chips can be arranged as desired. When RGB components (red, green, blue) are required, LED chips can be arranged according to the emission wavelength of RGB. Such L
A plurality of ED chips may be provided in the same insulating resin case, or a plurality of cases in which one LED chip is disposed may be used. Further, an RGB component or the like can emit light by using an LED chip and a fluorescent substance.

Specifically, InN, AlN, GaN, G
By combining a nitride-based compound semiconductor light capable of emitting high-energy light, such as aAlN, InGaN or InGaAlN, and a fluorescent substance that converts the light into a wavelength, an LED light-emitting body capable of emitting white light can be obtained. Examples of such fluorescent substances include perylene derivatives as organic fluorescent substances and yttrium / aluminum / inorganic fluorescent substances.
Garnet-based phosphors are exemplified.

In particular, the yttrium-aluminum-garnet-based phosphor activated with cerium is strong against heat, light and moisture, and the peak of the excitation spectrum can be set to around 450 nm. Further, the emission peak is around 530 nm and has a broad emission spectrum with a tail extending to 700 nm. Therefore, an ideal condition for converting blue light emission of the nitride-based compound semiconductor into white light emission is provided. More specifically, Y ₃ Al ₅ O ₁₂ : Ce or (Y, G
_{d) 3 Al 5 O 12:} Ce or the like can be suitably used. Such Y ₃ Al ₅ O ₁₂ : Ce or (Y, Gd) ₃ Al
An LED illuminant capable of emitting white light can be obtained by including a translucent material mixed with phosphor powder such as ₅ O ₁₂ : Ce of about several% in a sealing material provided in the case. Similarly, white light or the like can be obtained by disposing a sheet containing the phosphor powder on a light guide plate.

(Light Guide Plate 105) The light guide plate 105 used in the present invention is required to efficiently guide the light from the LED luminous body 301 into a planar shape, and is required to be excellent in transmittance and heat resistance and to be able to be formed uniformly. Can be In addition, the light guide plate 10
The shape of 5 can be various shapes such as a rectangle and a polygon as desired. As the thickness of the light guide plate 105 increases, the light use efficiency increases as the plate thickness increases. However, the thickness is preferably 10 mm or less in view of the arrangement, type, size, and the like of the LED light emitter.

LED chip 1 arranged on LED luminous body
02 is recognized as a point light source, so that the diffusion film disposed on the light guide plate 105 and the reflecting member 115 disposed on the end surface or the back surface of the light guide plate are arranged in a desired shape, and light emitted from the light guide plate 105 is emitted. It is preferable to make uniform surface light emission.
Further, projections for diffusing light are provided on the surface of the light guide plate 105 in a desired pattern. Alternatively, by printing a resin containing a scattering agent such as barium titanate in a desired pattern, light can be more uniformly emitted from the light guide plate.

The light guide plate of the present invention has a cutout on the side surface on the side to be coupled to the LED light emitter. The notch 325 formed in the light guide plate 305 can have various shapes such as a concave shape or a protruding shape as long as the LED light emitter can be locked by the hook portion. In addition, the notch 325 can be provided not only on the side surface of the light guide plate but also on the front and back surfaces of the light guide plate as desired. It is preferable that the width between the opposed notch bottoms provided on the light guide plate is smaller than the width between the opposed ends of the hook portions constituting the LED light emitting body 301 before being assembled to the light guide plate 305. Thereby, the elastic force of the lead frame 303 can be maintained, and the light emitting end face of the LED light emitting body 301 can be brought into close contact with the end face of the light guide plate 305. The mounting surface of the LED luminous body 301 to the light guide plate 305 may be disposed at every end surface or may be disposed only at a desired position.

As the light-transmitting material used for such light guide plates 105 and 305, polyester resin, vinyl chloride resin, polycarbonate resin, acrylic resin, glass, and the like are preferably exemplified. If white light is to be emitted by a combination of a blue LED chip and a fluorescent substance, LE
Not only the fluorescent substance can be arranged in the D light emitting body 301 but also the fluorescent substance can be arranged on the light guide plate 305. In any case, white light can be obtained by mixing colors of light from the LED chip and light from the fluorescent substance.

The electrical connection with the planar light-emitting device formed by incorporating the LED light-emitting body into the light guide plate 105 is similar to that of the lead frame 103 or the lead frame exposed from the insulating resin case 101 and the molded part 111. Each external terminal provided separately can be electrically connected to an external substrate by soldering or the like.

By disposing the liquid crystal device on the plane of the light guide plate of the planar light emitting device thus formed, a display device can be constructed. That is, in the liquid crystal device, the liquid crystal is sealed between the glasses having the transparent electrodes formed in a dot matrix. This can be driven by sandwiching this with a polarizing plate and supplying electric power between the transparent electrodes. The display device can be driven by supplying power to the LED chips together with the driving of the liquid crystal device. Hereinafter, embodiments of the present invention will be described in detail, but it goes without saying that the present invention is not limited to only the specific embodiments.

[0032]

【Example】

(Example 1) As shown in FIG.
One having three LED chips and three lead frames was used. As a lead frame, phosphor bronze having a thickness of 0.2 mm was formed by punching. After punching, the lead frame is silver plated. There are two types of lead frames, one that connects between insulating resin cases and one that is fixed to the light guide plate. Each lead frame is formed with external terminals that are partially exposed from the back side of the insulating resin case so that they can be electrically connected to the outside by soldering or the like. An end portion of the lead frame fixed to the light guide plate and an external terminal portion connected to the outside were formed by bending. In this way, a liquid crystal polymer terminal was insert-molded as a white heat-resistant insulating resin on the lead frame on which the hook portion and the external terminal were formed, thereby forming a case of the LED light emitting body.

The formed portion made of the insulating resin is 3
The insulating resin case at both ends except the center has LE
A recess in which a D chip can be placed is formed. In the recess, a part of the lead frame is exposed so as to be electrically connectable to each electrode of the LED chip.
The molded body serving as the central part is a molded part for an extraction electrode that contacts and supports the light guide plate.

Further, a gallium nitride-based compound semiconductor having InGaN as an active layer was formed on a sapphire substrate by MOCVD, and used as an LED chip capable of emitting blue light. The LED chip was die-bonded with epoxy resin in the concave portion of the formed portion. Each electrode of the LED chip and the lead frame in the cup were wire-bonded using a gold wire. Then, in the recess of the insulating resin case _{(Y 0. 8 Gd 0.2) 3} Al 5 O 12: Ce is to form a seal cured at 120 ° C. 2 hours poured translucent epoxy resin contained . As a result, an LED light-emitting body was formed in which the end portion of the lead frame had a hook portion and the two insulating resin cases were connected by the lead frame and the molded body.

On the other hand, an acrylic resin having a thickness of 5 mm was cut out as a light guide plate and the end face was polished. A notch is provided on the side surface on the side coupled with the LED light emitter. Acrylic resin containing barium oxide is applied to the light guide plate in a dot shape so that the light emission intensity is constant. The reflection layer was formed except for the surface of the light guide plate from which light was emitted to the end face, the cutout portion of the light guide plate, and the end face where light from the LED light emitter was incident. The reflection layer is made of polycarbonate resin 10
A reflectance of 99% is obtained by injection molding 70 g of barium titanate in 0 g.

The cutout portion of the formed light guide plate and the hook portion of the LED luminous body were fitted together and pressed by an external force to form a planar light emitting device. The hook part and the notch part were fitted to each other, and the LED light-emitting body was easily fixed. In addition, when the entire lead frame of the LED illuminant is on the inside (light guide plate side), the opening of the LED illuminant from which light from the LED chip is emitted is pressed by a certain elasticity.

The polycarbonate is provided on the light emission observation surface of the light guide plate.
The diffusion layer, which is an embossed film,
Was placed. A power supply is connected to the planar light emitting device
Then, uniform white light emission was obtained from the main surface side
Was done. Brightness is 84 cd / m ^TwoMet. Also this
The planar light emitting device formed as described above can be used for temperature and humidity cycle tests.
The LED light-emitting body is
The light emitting surface presses the end face of the light guide plate, and the light emission brightness may change.
And not.

[0038]

According to the planar light emitting device of the first aspect of the present invention, the LED light emitter is assembled to the light guide plate by snap fitting to the notch portion of the diffusion light guide plate using the elasticity of the hook portion. Only accurate positioning is not required. Therefore, it is extremely easy to assemble, and after assembling, the hook is locked by the elastic force of the hook portion, so that it cannot be easily removed. Further, after each external terminal is fixed to an external substrate or the like by soldering, that is, in an actual use state, the coupling is further strengthened by the fixing force of the terminal.

Further, the width between the notch facing surfaces of the light guide diffuser plate is made smaller than the width between the hook facing surfaces before assembling the LED light emitter, so that the hook portion is always wider after assembling than before assembling. State. Therefore, the hook tip always presses the notch with its elastic force. The depth of the LED luminous body with respect to the diffusion light guide plate is fixed by the frictional force between the hook tip and the notch surface contact portion. In addition, this elastic force tends to cause the LED light emitter to bow. This bending force causes the light output surface, which is the end surface, to come into close contact with the end surface of the light guide plate. Therefore, light leakage loss from the light exit surface and the light guide surface can be reduced, and light can be efficiently guided into the diffused light guide plate. That is, a high-luminance planar light emitting device is obtained.

According to the planar light emitting device of the second aspect of the present invention, the exposed portion of the lead frame, that is, the non-formed portion is provided, and the length of the insulating resin case is divided into short portions. Therefore, the warpage generated in the LED luminous body during molding is relatively small. Further, the divided insulating resin case can be easily deformed. By this deformation, the inclination of the light exit surface with respect to the introduction surface can be absorbed, and it becomes easier to adhere to the end surface of the diffusion light guide plate.

According to the planar light emitting device of the third aspect of the present invention, the LED luminous body comes into close contact with the end face of the light guide plate by the elastic force of the lead frame. Therefore, light leakage loss from the light exit surface and the light guide surface can be reduced, and light can be efficiently guided into the diffused light guide plate. That is, a high-luminance planar light emitting device is obtained. Since the light emitting end face of the LED illuminator and the light guide plate end face are always crimped, it is possible to provide a planar light emitting device in which light emission unevenness does not occur even in use conditions.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a planar light emitting device used in the present invention.

FIG. 2 is a schematic front view of a planar light emitting device used in the present invention.

FIG. 3 is a schematic perspective view of another planar light emitting device used in the present invention.

FIG. 4 is a schematic transparent perspective view of a planar light emitting device shown for comparison with the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 ... Insulating resin case 102 ... LED chip 103 ... Lead frame 104 ... Hook part 105 ... Light guide plate 111 ... Molding part 113 ... Lead which connects insulating resin cases. Frame 114: External extraction electrode constituting a part of the lead frame 115: Reflector 301: LED luminous body 303: Lead frame 305: Light guide plate 315: Reflector 325 ... Notch portion of light guide plate 401 Light emitting diode 402 LED chip 403 Lead frame 405 Light guide plate

Claims (3)

[Claims] An LED light-emitting body having a lead frame electrically connected to an LED chip disposed on an inner bottom surface of an insulating resin case having an open front surface and extending from the inside of the insulating resin case to the outside; A light guide plate formed of a plate having a substantially flat shape and having translucency, and light from the LED luminous body being able to enter through an end surface of the plate body, the planar luminous device comprising: The lead frame is made of an elastic metal body, and its outwardly extending end has a hook shape, and the hook shape is engaged with notches provided at both ends of the light guide plate. Surface light emitting device. 2. The planar light emitting device according to claim 1, wherein said LED light emitter has an insulating resin case in which an LED chip is arranged and divided into a plurality of parts, and each is connected by a lead frame. 3. An LED light emitter having a lead frame electrically connected to an LED chip disposed on an inner bottom surface of an insulating resin case having an open front surface and extending from the inside of the insulating resin case to the outside, A light guide plate formed of a plate having a substantially flat shape and having translucency, and light from the LED luminous body being able to enter through an end surface of the plate body, the planar luminous device comprising: The lead frame is made of an elastic metal body, and the end of the lead frame extending to the outside and the light guide plate are locked.
A planar light emitting device, wherein a D light emitter is pressed against a light guide plate.