JP2008251561A - Display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extremely thin display. <P>SOLUTION: The display 100 comprises a circuit wiring board 10 consisting of a substrate 10a into which a light diffusion material is dispersed and circuit wiring 10c, a group III nitride based compound semiconductor light-emiting element 201, wire bonding 3n and 3p, and a shading material 4. A minute prism surface 10af is formed on the circuit wiring board 10. The group III nitride based compound semiconductor light-emiting element 201 has an insulating substrate 20, an n-type region 21n, and a p-type region 22p in this order. When the light emitted from a light-emiting region (bold line) A reaches the substrate 10a of the circuit wiring board 10, the light is diffused by the light diffusion material dispersed into the substrate 10a and an extremely wide region of the substrate 10a in the circuit wiring board 10 is brought into a state like a secondary emission source (bold line arrow). Consequently, the whole minute prism surface 10af (region B) covered with the shading material 4 is viewed as if it is emitting light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device that uses a semiconductor light emitting element that is a point light source and is visually recognized as if a certain region is emitting light. The present invention also relates to a thin display device using 1 to 10 or more light emitting diodes. The present invention is particularly useful as a device for turning on / off the power of various devices or displaying an operation status by switching between lighting and non-lighting. Note that switching between lighting and non-lighting includes switching of the color tone in the display device by lighting one or all of the light emitting diodes having different color tones. It should be noted that the present invention does not exclude a case where the color tone of the display device is arbitrarily adjusted by adjusting the light emission intensity of each light emitting diode having a different color tone.

Gallium nitride blue and green light emitting diodes are provided at a relatively low cost, and the three primary colors of light emitting diodes are aligned with gallium arsenide red light emitting diodes, and there are a variety of full color display matrices and full color display devices. Has been developed. For example, Patent Document 1 discloses a mobile phone display device using a plurality of light emitting diodes in which a light extraction region forms one character (symbol).
JP 2002-51135 A

  In Patent Document 1, a light emitting diode is provided on a circuit wiring board, and a partition wall is provided so that light emission does not leak to other display areas. With such a configuration, a sufficiently thin display device cannot be configured.

  The present inventors have conceived a sufficiently thin display device based on a completely new idea and completed the present invention.

  The invention according to claim 1 includes a circuit wiring board in which circuit wiring is formed on a first surface, and a light emitting element disposed on the first surface of the circuit wiring board and connected to the circuit wiring. An unevenness is formed in the light transmission region of the second surface on the light extraction side opposite to the first surface of the circuit wiring board. Here, the circuit wiring board needs to be at least not light-shielding, but does not necessarily need to be highly transmissive. For example, for the purpose of visual effect, it may have any translucency (transmittance with respect to the wavelength of light) such as a so-called smoked or colored one. In addition, the unevenness formed on the second surface of the circuit wiring board may be formed so as to completely cover the second surface of the circuit wiring board, that is, there is no portion where the unevenness is not formed. It does not have to be formed as a whole.

The invention according to claim 2 is characterized in that the unevenness formed on the second surface of the circuit wiring board forms a Fresnel lens. For example, the Fresnel lens is designed with respect to the center of the light emitting region of the corresponding light emitting element. In this case, for example, when a plurality of light emitting elements are formed, the second surface of the circuit wiring board may be divided into a plurality of light emitting elements, and a Fresnel lens may be formed for each of the regions. It is also possible to subdivide the regions constituting the layered structure so that adjacent individual regions become Fresnel lens constituent parts of different light emitting elements.
The invention according to claim 3 is characterized in that the unevenness formed on the second surface of the circuit wiring board is composed of a large number of microprisms, a large number of microlenses, or a large number of lenticular lenses. A large number of microprisms refers to a density of irregularities having a prism action, such as a triangular prism shape, a pyramid shape, or a conical shape, having a height difference of less than 1 mm and regularly or irregularly. A large number of lenticular lenses means a state where so-called bowl-shaped lenses are densely packed.
The invention according to claim 4 is the invention according to claim 3, wherein the circuit wiring board includes a light diffusing material or a phosphor made of a light-transmitting base material and dispersed in the base material. And For example, a phosphor is a substance that converts the light emission wavelength of a light emitting diode. It is assumed that light of the light emission wavelength of the light emitting diode itself and light of the light emission wavelength converted by the phosphor are combined to be visible in other colors. To do. The light diffusing material does not extract light from the light emitting diode only in the linear direction, but allows the entire light transmission region to be visually recognized as emitting light from any direction. The circuit wiring board in which the light diffusing material or the phosphor is dispersed is not limited to the circuit wiring board in which the light diffusing material or the phosphor is uniformly dispersed in the thickness direction of the circuit wiring board. And a material in which a light diffusion material or phosphor is dispersed.

The invention according to claim 5 is characterized in that a translucent resin is formed on the second surface of the circuit wiring board, and a light diffusing material or a phosphor is dispersed in the translucent resin. And
The invention according to claim 6 is characterized in that the second surface of the circuit wiring board is formed with a light-shielding portion formed in a portion excluding the light transmission region through which light is transmitted.
In these cases, the translucent resin and the light shielding portion may be in contact with the second surface of the circuit wiring board. At this time, the translucent resin and the light-shielding portion may be inserted into the concave and convex portions on the second surface of the circuit wiring board. Otherwise, the translucent resin and the light-transmitting resin and only near the top of the concave and convex portions The structure which the light-shielding part contacted may be sufficient. Or the unevenness | corrugation of the 2nd surface of a circuit wiring board does not need to be formed in the part in which the light-shielding part is formed.
Alternatively, the translucent resin and the light shielding portion may be formed so as not to contact the second surface of the circuit wiring board. A film made of, for example, another translucent material may be formed between the second surface of the circuit wiring board and the translucent resin and the light shielding portion.
In addition, the light-shielding part includes both a light reflecting material and a light absorbing material. For example, when using a light reflecting material, it is preferable to provide a light absorbing material on the viewing side from the viewpoint of vision. .

  When a light emitting element is provided on the first surface on the circuit wiring formation side of the circuit wiring board and light is extracted on the second surface on the opposite side, an extremely thin display device can be obtained. However, for example, when a semiconductor light emitting element is used, the light emitting portion of a chip of several hundred μm square is usually visually recognized only as point light emission. For this reason, even if light is extracted through a circuit wiring board having a thickness of about 2 mm or less, the display device is still visible as point light emission, and forms a light emitting area of, for example, several mm square to several cm square. As it is difficult to use as it is. Therefore, irregularities are formed on the second surface of the circuit wiring board. By this unevenness, the radiation direction of light emitted from the point light source in all directions can be changed. As a result, when the light is dispersed, a wide area of the second surface emits light when viewed from the front (normal direction of the first surface and the second surface) or from an oblique direction. It can be visually recognized as follows. Alternatively, by aligning the direction of the light, for example, it is possible to concentrate the light only in the front direction (the normal direction of the first surface and the second surface).

  In order to align the light direction, a Fresnel lens is preferable as a structure provided on a relatively thin circuit wiring board. That is, a large number of concentric annular prisms having a small height difference are formed. In order to disperse the direction of light irregularly, a large number of microprisms, a large number of microlenses, or a large number of lenticular lenses are packed together. When the direction of light is irregularly dispersed, it is better to disperse the light diffusing material inside the circuit wiring board (claim 4). If the phosphor is dispersed instead of the light diffusing material, light different from the color tone of the light emitting element can be taken out in addition to the effect of irregularly dispersing the direction of light.

  When the direction of light is irregularly dispersed, a light-transmitting resin layer is provided to disperse the light that has passed through the irregularities further irregularly, and the light diffusion material is dispersed in the resin layer. And good. When the phosphor is dispersed instead of the light diffusing material, in addition to the effect of irregularly dispersing the direction of light, it is possible to extract light having a color tone different from that of the light emitting element. In order to shape the light transmission region into a desired shape, it is preferable to provide a light shielding part. The light shielding portion may be formed of a thin light shielding film, for example, or may be a partition made of a thick light shielding material.

The light-emitting element used in the present invention is preferably a semiconductor light-emitting diode in that it is small. The light emitting diode can be monochromatic, full color, or any other color. Further, the number of light emitting diodes used in one region forming one symbol is also arbitrary. As the light emitting diode, a light emitting diode which emits light having a necessary color tone can be arbitrarily selected. For example, a purple or green light emitting diode using a group III nitride compound semiconductor (Al _x Ga _y In _1-xy N) may be selected. When combined with a phosphor, a light emitting diode having an emission wavelength in the near ultraviolet to blue region and a yellow phosphor may be combined to form a white diode, or a phosphor of a desired color and an ultraviolet light emitting diode may be combined.

The electrode structure of the light emitting diode is also arbitrary, and the connection method with the circuit wiring of the circuit wiring board can be arbitrarily selected. For example, when using a group III nitride compound semiconductor (Al _x Ga _y In _1-xy N) light emitting element, a reflective film is formed on the back surface of the chip substrate with a so-called face-up type structure (light extraction on the p-type semiconductor layer side). You may do it. In this case, the connection to the circuit wiring board may be a solder bump. Alternatively, a so-called flip chip type structure (light extraction on the insulating substrate side) having a reflective film on the p-type semiconductor layer side may be wire-bonded. When performing wire bonding, wedge bonding using ultrasonic waves eliminates the need for heat treatment and reduces the adverse effects on other components. Details of these will be described later.

  The material of the circuit wiring board is completely arbitrary except that a light-shielding base material is inappropriate. The base material is preferably a light-transmitting resin or inorganic material. When the wiring material corresponding to the light transmission region is made of indium tin oxide (ITO), the shadow of the wiring does not occur during display. However, a light-shielding conductor such as copper or aluminum is not excluded as a wiring material. As the light diffusing material, spherical or other fine particles are available, and in addition to being dispersed in the base material of the circuit wiring board, a thin film coated and fixed with the light diffusing material may be used. The same applies to the case of using a phosphor or an organic dye. The method of forming the irregularities on the second surface of the substrate may be formed at the time of injection molding or may be formed by cutting or the like later.

  The material for forming the light-shielding portion is basically preferably a light absorbing material, but may have a double structure with a light absorbing material having the circuit wiring board side as a light reflecting material. The light shielding portion can be formed by screen printing, vapor deposition, or other methods corresponding to the material to be used. A film with a light shielding material may be attached. The sealing resin is completely arbitrary with respect to the base material resin and other additives, and can be arbitrarily selected when a light diffusing material, a phosphor, an organic dye or the like is contained. In the present invention, replacing the sealing resin with an inorganic material is not excluded.

  If a reflective film is formed so as to cover the light emitting diode, the light extraction efficiency to the second surface side can be improved. In this case, any metal or the like can be used. However, in order to maintain insulation from the circuit wiring of the circuit wiring board, a device such as an insulating material is required. Of course, a housing or other configuration in which a reflective film is formed on the inner surface so as to face the first surface of the circuit wiring board may be used.

  FIG. 1 is a cross-sectional view showing a configuration of a display device 100 according to a specific first embodiment of the present invention. The display device 100 of FIG. 1 includes a circuit wiring board 10 including a substrate portion 10a in which a light diffusion material is dispersed and circuit wiring 10c, a group III nitride compound semiconductor light emitting element 201, wire bondings 3n and 3p, and a light shielding member. It consists of four. A micro prism surface 10af is formed on the second surface of the circuit wiring board 10 opposite to the first surface on which the circuit wiring 10c is formed. The group III nitride compound semiconductor light emitting device 201 includes an insulating substrate 20, an n-type group III nitride compound semiconductor region 21n, and a p-type group III nitride compound semiconductor region 22p in this order. In FIG. 1, the light emitting region is indicated by a thick line A sandwiched between an n-type group III nitride compound semiconductor region 21n and a p-type group III nitride compound semiconductor region 22p. The region A can be a light emitting layer having a single layer, a single quantum well structure, or a multiple quantum well structure in addition to the pn interface, and is simply illustrated. Although not shown in FIG. 1, an n-electrode is provided between the n-type group III nitride compound semiconductor region 21n and the wire bonding 3n, and between the p-type group III nitride compound semiconductor region 22p and the wire bonding 3p. Suppose that a p-electrode is formed. In FIG. 1, the circuit wiring 10 c is described as if it covers most of the area where the group III nitride compound semiconductor light emitting element 201 is not disposed on the lower side of the substrate portion 10 a in FIG. 1. 10c may be formed so as to be able to energize the group III nitride compound semiconductor light emitting device 201, and does not need to cover the lower side of the substrate portion 10a.

  In the display device 100 of FIG. 1, when the light emitted from the light emitting region (thick line) A of the group III nitride compound semiconductor light emitting element 201 reaches the substrate portion 10a of the circuit wiring substrate 10, Light is diffused by the dispersed light diffusing material. As a result, the extremely large area of the substrate portion 10a of the circuit wiring board 10 becomes the same state as the secondary light emitting source. This is indicated by a thick arrow in FIG. That is, the light from the light emitting region (thick line) A diffuses in various directions within the substrate portion 10a. Thus, the diffused light reaches the minute prism surface 10af and irregularly refracts, so that the entire light transmission region B that is not covered by the light shielding member 4 is visually recognized as if it is emitting light. As described above, the display device 100 in FIG. 1 emits light from the group III nitride compound semiconductor light emitting element 201 as a point light source from the entire light transmission region B by the substrate portion 10a in which the light diffusion material is dispersed. It can be visually recognized. Therefore, by forming the light shielding member 4 in a desired shape, it is possible to provide a display device for the light transmission region B that is shaped into a desired shape. The action of the minute prism surface 10af is to be visually recognized as more uniformly emitting light.

[Modification 1]
FIG. 2 is a cross-sectional view showing a configuration of a display device 150 corresponding to a modification of the display device 100 of FIG. The display device 150 in FIG. 2 includes the light shielding member 4 as a wall-shaped light shielding member 4w in the configuration of the display device 100 in FIG. 1, and a light diffusing material in a region surrounded by the wall-shaped light shielding member 4w. Is filled with a translucent resin 5 and covered with a translucent plate 6. In the display device 150 of FIG. 2, similarly to the display device 100 of FIG. 1, after the diffused light passes through the microprism surface 10af, it is further diffused by the translucent resin 5 in which the light diffusion material is dispersed. Thereby, it is visually recognized that the light transmission region B shaped into a desired shape emits light more uniformly.

  FIG. 3 is a cross-sectional view showing a configuration of a display device 200 according to a second specific example of the present invention. The display device 200 of FIG. 3 includes a circuit wiring board 103 composed of a transparent substrate portion 10b and circuit wiring 10c, a group III nitride compound semiconductor light emitting element 201, wire bondings 3n and 3p, and a light shielding member 4. . A Fresnel lens 10bf is formed on the second surface of the circuit wiring board 10 opposite to the first surface on which the circuit wiring 10c is formed. The configuration of the group III nitride compound semiconductor light emitting device 201, the circuit wiring 10c, and the connection method thereof are the same as those of the display device 100 of the first embodiment.

  In the display device 200 of FIG. 3, when light emitted from the light emitting region (thick line) A of the group III nitride compound semiconductor light emitting element 201 reaches the Fresnel lens 10 bf of the circuit wiring board 10, the light is almost parallel. It is configured to be output. As a result, it becomes the same state that a very wide area of the substrate portion 10b of the circuit wiring board 10 has become a secondary light source that emits parallel rays. This is indicated by thick arrows in FIG. Thus, the entire light transmission region B that is not covered with the light shielding member 4 is visually recognized as if it emits parallel rays. As described above, in the display device 200 of FIG. 3, the light emission of the group III nitride compound semiconductor light-emitting element 201 that is a point light source is the parallel light emission from the entire light transmission region B by the Fresnel lens 10 bf. Visible. Therefore, by forming the light shielding member 4 in a desired shape, it is possible to provide a display device for the light transmission region B that is shaped into a desired shape. The display device 200 according to the present embodiment is a display device that has good visibility from the designed viewing direction (upper in FIG. 3) and is difficult to view from an oblique direction.

[Modification 2]
FIG. 4 is a cross-sectional view showing a configuration of a display device 250 corresponding to a modification of the display device 200 of FIG. The display device 250 in FIG. 4 includes the light shielding member 4 as a wall-shaped light shielding member 4w in the configuration of the display device 200 in FIG. 3, and a light diffusing material in a region surrounded by the wall-shaped light shielding member 4w. Is filled with a translucent resin 5 and covered with a translucent plate 6. As in the display device 200 of FIG. 3, the display device 250 of FIG. 4 diffuses the parallel light beam that has passed through the Fresnel lens 10 bf with the translucent resin 5 in which the light diffusion material is dispersed. The light transmission region B shaped into a shape is visually recognized as emitting light. The display device 250 of the present modification is a display device that can be easily viewed from any oblique direction.

  As the circuit wiring board 10a of the first embodiment and the translucent resin 5 of the modified examples 1 and 2, a material in which a light diffusion material is dispersed is used, but a material in which a phosphor is dispersed may be used. . When a phosphor is used, light having a wavelength different from the emission wavelength of the group III nitride compound semiconductor light emitting device 201 can be emitted from the phosphor. For example, if the emission wavelength of the group III nitride compound semiconductor light emitting device 201 is set to the blue region and a phosphor that absorbs the emission wavelength and emits yellow fluorescence is used, white light emission can be obtained from the light transmission region B. It is. Alternatively, if the emission wavelength of the group III nitride compound semiconductor light emitting device 201 is in the ultraviolet region and a phosphor that absorbs the emission wavelength and emits fluorescence of any color is used, light emission of any color can be obtained from the light transmission region B. Is also possible. At this time, if phosphors having different fluorescent colors are mixed, the color tone can be adjusted more easily. Further, if a colored plate is used as the substrate portion 10a in FIG. 1, the color tone of the light emitting element can be changed.

  In each of the above embodiments, wire bonding is shown as a method for mounting a group III nitride compound semiconductor light-emitting element on a circuit wiring board. However, wedge bonding using ultrasonic waves can be suitably used as the wire bonding method. . In each embodiment, the light is extracted from the substrate 20 side. However, for example, the light is extracted from the p-type group III nitride compound semiconductor region 22p side by using a flip-chip mounting method on the circuit wiring board. It is also good. In this case, a light-transmitting electrode is preferably used as the electrode provided in the p-type group III nitride compound semiconductor region 22p.

In the group III nitride compound semiconductor light-emitting device 201 of each example, the p-electrode and the n-electrode (not shown) are made highly reflective electrodes so that light leaking downward from the light-emitting region A in each figure can be obtained. The circuit wiring board 10 can be reflected to the board portion 10a side. The reflective film may be further formed as a casing or a cover.
It is also optional to seal the group III nitride compound semiconductor light emitting element 201 with resin or to cover the circuit wiring 10c with an insulating material.

  Although the example which formed the light shielding member 4 or 4w in the circuit wiring board 10 directly was shown in the said Example, after forming in another film, for example, the method of adhere | attaching the circuit film board 10 on the whole film can also be taken.

  The present invention is not limited to the above embodiments. On the basis of the configuration described in the embodiment, it can be appropriately changed using any available member. For example, the light-emitting element is not limited to a group III nitride compound semiconductor light-emitting element, and red to yellow-green GaAs-based or InP-based light-emitting elements may be used. When an element using a conductive chip substrate is connected to circuit wiring, the substrate may be directly connected to circuit wiring. In the present invention, it is only necessary to visually recognize as if the light transmission region B composed of the region where the light shielding member is not formed is finally shining, and the circuit wiring, the light emitting element, and the wire, solder, bump, etc. for conducting them. It is not always necessary to use a translucent material. The light diffusing material may be dispersed in both the substrate portion of the circuit wiring board and the sealing resin, and a thin film (light diffusing sheet) having the light diffusing material may be stacked on the light extraction side. Naturally, the combined use of the light diffusing material and the phosphor is included in the present invention.

In addition, the fixing method to the circuit wiring board of a light emitting element is arbitrary. The description of the substrate having an insulating substrate is omitted in the figure, but an adhesive may be used.
Further, for example, the film of the group III nitride compound semiconductor light emitting device 201 may be formed by dipping in a paste containing a highly reflective member.

  The present invention can be used for arbitrary display applications by displaying symbols in units of light emitting areas or displaying numerical values or the like by a two-dimensional arrangement of light emitting areas, such as a display device on a front panel of a vehicle, It can be used for digital display clocks and display parts of home appliances. Moreover, it can be set as the operation part of the push-down switch which has a function which displays an ON / OFF state by lighting / non-lighting.

1 is a cross-sectional view showing a configuration of a display device 100 according to a first specific example of the present invention. Sectional drawing which shows the structure of the display apparatus 150 of the modification 1. FIG. Sectional drawing which shows the structure of the display apparatus 200 which concerns on the specific 2nd Example of this invention. Sectional drawing which shows the structure of the display apparatus 250 of the modification 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,103: Circuit wiring board 10a: The board | substrate part in which the light-diffusion material was disperse | distributed 10af: The microprism formed in the board | substrate part in which the light-diffusion material was disperse | distributed 10b: The board | substrate part which consists of a transparent material 10bf: From a transparent material Fresnel lens 10c formed on the substrate portion comprising: circuit wiring 201: Group III nitride compound semiconductor light-emitting element 4, 4w: light shielding member 5: sealing resin in which light diffusion material is dispersed 6: translucent plate material A : Light emission region of group III nitride compound semiconductor light emitting device 201 B: Light transmission region composed of a region where the light shielding member 4 or 4w is not formed

Claims (6)

A circuit wiring board having circuit wiring formed on the first surface;
A light emitting element disposed on the first surface of the circuit wiring board and connected to the circuit wiring;
An unevenness is formed in the light transmission region of the second surface on the light extraction side opposite to the first surface of the circuit wiring board. The display device according to claim 1, wherein the unevenness formed on the second surface of the circuit wiring board forms a Fresnel lens. 2. The display device according to claim 1, wherein the unevenness formed on the second surface of the circuit wiring board includes a plurality of microprisms, a plurality of microlenses, or a plurality of lenticular lenses. The display device according to claim 3, wherein the circuit wiring board includes a light-transmitting base material and includes a light diffusion material or a phosphor dispersed in the base material. 2. The translucent resin is formed on the second surface of the circuit wiring board, and a light diffusing material or a phosphor is dispersed in the translucent resin. The display device according to claim 4. 6. The light-shielding part formed in the part except the light transmissive area | region which permeate | transmits light is formed in the said 2nd surface of the said circuit wiring board, The Claim 1 thru | or 5 characterized by the above-mentioned. Item 1. A display device according to item 1.

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