JPH0863119A - All-color image display device using monochormatic led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a whole color image display device using single-color LED and its producing method. SOLUTION: The whole color image display device is provided with a substrate 45, a transparent plate 60 adjacently attached to the substrate and different fluorescent bodies 67 and 68 which are separately attached to the plate. The respective fluorescent substances are positioned inside different areas. When they collide with an optical element having energy being sufficient to excite them, the different fluorescent substances respectively generate different color lights. Plural GaNLEDs 40, 41 and 42 are formed on the substrate and the optical elements having energy being sufficient to excite the fluorescent substances and to emit the lights are discharged. The optical elements are made incident on the different one of the plural fluorescent substances. A whole color image is formed by single-color red and green fluorescent substances and blue lights from some of GaNLED.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to full color images.
image), and more particularly to an all-color display using monochromatic light emitting diodes.

[0002]

2. Description of the Related Art A light emitting diode (LED) has a large number of L's.
Manufactured as an array containing EDs, virtual images
tmage) is used in image devices. One of the problems with LED arrays used in such devices is the fact that only one color is available. In the first device, the LED used was only able to emit red light, so the image produced was also red and relatively difficult to see. Later models also used orange and amber LEDs, but the image was still single color.

Since the types of available LEDs are limited, the types of colored light are also limited. The problem is
To produce a full-color image, each pixel produces three different L's to produce three colors (usually red, green and blue).
The ED must be included. Therefore,
LEDs for producing full-color images, because each of the different types of LEDs must be manufactured separately for each pixel
The manufacture of arrays is very complex. Thus, all colors L
In order to manufacture an ED array, three different manufacturing processes must be carried out continuously and completely.

Yet another problem with conventional LEDs is that they are very inefficient and produce very low output.
For example, the amount of light produced by an LED array is so low that the image produced must be viewed directly or by a virtual image (magnification, etc.). Prior art L
EDs cannot produce enough light to form an image on, for example, a remote screen.

Therefore, it would be advantageous to be able to produce a full color image from a single color LED array.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a new and improved all color image display device using single color LEDs.

Another object of the present invention is to provide a multi-color phosphor (multi-c).
It is an object of the present invention to provide a new and improved all-color image display device using a single-color LED array that generates photons of sufficiently high energy to excite olor phosphors).

Yet another object of the present invention is to provide a new and improved method of manufacturing an all color image display device using a single color LED array.

[0009]

SUMMARY OF THE INVENTION A substantial solution to the above and other problems, and the realization of the above and other objectives are to provide a substrate and a plurality of single color light emitting diodes (LEDs) formed thereon. And an all-color image display device including An optically transparent plate is attached adjacent to the substrate and a plurality of discrete areas are defined thereon.
Further, the arrangement of the plates is determined such that the light emitted by each of the plurality of LEDs is incident on each one of the plurality of discrete areas of the plate. A plurality of different phosphors are separately attached to the plate, each in a different one of the plurality of separate areas of the plate,
Light from different ones of the LEDs is positioned to impinge. Each of the different phosphors produces a different color of light when impacted by the light from the LED.

The substantial solution of the above and other problems, and the realization of the above and other objects include forming a plurality of single color light emitting diodes on a substrate.
This is achieved in a method for manufacturing an all-color image display device. The LEDs are positioned such that the photons emitted from each of the plurality of LEDs are directed to different ones of the plurality of distinct regions on the surface spaced from the substrate. Multiple LEs emitting photons
When properly energized, each of the D's produces sufficient energy to excite the phosphor and emit light. An optically transparent plate is provided on which a plurality of discrete areas are defined,
A plurality of different phosphors are separately fixed to this plate, each in a different one of a plurality of distinct regions of the plate. Each different phosphor produces a different color of light when bombarded by photons that have sufficient energy to excite the phosphor. The plate is mounted adjacent to the substrate and the phosphors in the discrete regions of the plate are each positioned in one of the discrete regions in a plane spaced from the substrate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring specifically to FIG. 1, a ridge t
ype) A light emitting diode (LED) 15 is shown. L
The ED 15 is a substrate 16 and a buffer layer formed on the substrate 16.
(buffer layer) 17 is included. A first conductivity type first ohmic layer 18 is positioned on the buffer layer 17, and a first conductivity type first cladding layer 19 is positioned on the first ohmic layer 18. There is. An active layer including one or more quantum wells is located on the cladding layer 19, and a second conductivity type second cladding layer 21 is located on the active layer 20. A second ohmic layer 22 is positioned on the second cladding layer 21 and defines a light emitting surface or area of the LED 15.

Electrical contacts 23 are formed on the second ohmic layer 22. The electrical contacts 23 may be uncoated and patterned to surround the light emitting region, or an optically transparent material (eg, ITO) may be used to allow emitted light to pass through. The second electrical contact 24 is the substrate 16
Located on the back side of the substrate or on the top surface as shown in FIG. In the particular embodiment of FIG. 1, the substrate 16 is semi-insulating.
Insulating), etching or removing some of the layers 18, 19, 20 to allow the second electrical contact 24 to be formed in contact with the first ohmic layer 18. In this particular embodiment, contact 23 is a p-type contact and contact 24 is an n-type contact on the opposite side of the diode. As is known,
By applying an appropriate current between the electrical contacts 23, 24, the active region 20 is activated and passes through the emission region in the upper surface of the ohmic layer 22 to emit light of a specific wavelength.

The substrate 16 and the various layers formed thereon have a relatively large area (eg, a semiconductor wafer, etc.) on which thousands of LEDs are typically formed in a predetermined array. Layers 21 and 22 are etched or material is removed to separate each LED in one or more arrays from all other LEDs.

As a specific example, in this embodiment, the substrate 16 is wholly formed of silicon carbide (SiC), sapphire, or lead oxide (ZnO). The buffer layer 17 is formed of low temperature aluminum nitride (AlN) or gallium nitride (GaN). The first ohmic layer 18 is formed of n-type GaN, and the first cladding layer 19 is formed of n-type aluminum gallium nitride (AlG).
aN). The active layer 20 is made of indium gallium aluminum nitride (InGaAlN) and contains several quantum wells. The second cladding layer 21 is formed of p-type AlG.
The second ohmic layer 22 is formed of aN, and the second ohmic layer 22 is formed of p-type GaN. The various layers 17-22 are MOCs known in the art.
It is epitaxially grown on the substrate 16 by using an epitaxial technique such as VD. The LED 15 emits light (blue) having a wavelength of about 450 nm. This emission wavelength can be somewhat increased or decreased by using a band gap mechanism, and an emission wavelength in the range of about 380 nm to 520 nm can be obtained.

The LED 15 is a highly efficient diode manufactured on a substrate by new materials and semiconductor technology, and can carry more heat than ever before, thus enabling more efficient operation. . Current GaN
The LED can generate power of about 15 mA and 1 mW or more, and more specifically, the LED 15 has a power of about 40 m.
It produces a blue color with an output power of A and 2 mW. This output power is converted to an output of about 11 lumens / watt.

A second type of LED is shown in FIG. This is what is generally called a planar type LED. In this type, L between adjacent LEDs on the chip
ED isolation is achieved by implanting a region 25 of high resistance or opposite conductivity type into the upper layer. The high resistance region 25 formed in a ring shape is a central portion in the region 25.
It restricts the current flow to the (central region) and effectively separates the central part from all surrounding materials. The advantage of this type of LED is that the top surface is planar and that it can be used to easily support structures added thereon without the additional step of providing a planarization layer. Is.

The light emitted from an LED is usually Lambertian (ie, it is usually emitted in a hemispherical shape).
Therefore, there is an advantage in that a light splitting unit that prevents or reduces crosstalk between adjacent LEDs is provided.
Crosstalk typically occurs when light from one LED is incident on another LED, or when it appears to be emitted from the emission area of the other LED. One way to provide a light split is to form a ridge 27 on the top surface of the chip or wafer that surrounds the emitting area of each LED and directs the light in the desired direction. In some cases, raised portions 27 may be formed of a light absorbing material to further prevent or reduce reflections and resulting crosstalk. For example, when the LED emits red light, the ridge 27 is made of germanium that absorbs red light.

Phosphors are capable of producing very bright light in a great variety of colors. Usually, in order to excite the phosphors, they must be bombarded with high energy electrons or high energy photons. For example, it is common to manufacture cathode ray tubes (CRTs) capable of producing full-color images, but to produce a stream of electrons with sufficient energy to excite the phosphors on the faceplate of the CRT. To generate, CRTs require large amounts of power and excessively high voltages.

Although some suggestions have been made to replace the electron gun in the CRT with a semiconductor laser, the known LE of the prior art is known.
Not all D produces light with enough energy to excite the fluorophore. Due to the high efficiency of the GaN LEDs mentioned above, and due to the wavelength of the emitted light, the emitted photons (light) excite the phosphor and the secondary emission.
It has a high enough energy to perform (secondary emission). As shown in the graph of FIG. 4, a typical phosphor used herein absorbs photons containing a photon of wavelength 450 nm (curve 28) and emits photons of different wavelengths (curve 29). In this example, the green phosphor absorbs photons (blue light) with a wavelength of 450 nm and emits photons (green light) with 550 nm. Typically, the conversion rate is 50% -100
%. That is, absorption of one 450 nm photon results in the emission of one 550 nm photon.

Referring specifically to FIG. 5, an LED array similar to the array shown in FIG. 2 is shown. LED
Part of the array is disassembled and three LEDs 40, 41, 42
This description will be simplified by showing only one. LEDs 40, 41, 42 are formed on a substrate 45, a buffer layer is formed as part thereof (or as an additional layer thereover, depending on the application), and a first
Ohmic layer 46, first cladding layer 47, active region 5
0, the second cladding layer 52, and the second ohmic layer 5
3 is continuously formed on it. High resistance region 55
Are formed by injecting into the second ohmic layer 53,
0, 41, 42 are isolated from each other and also from other LEDs in the array. In addition, the material layer 57 is positioned on the upper surface of the second ohmic layer 53, and the protrusion is formed by patterning. The ridges act to direct light outward (upward in FIG. 5) and away from adjacent LEDs.

In general, the plate 60 is positioned adjacent to the substrate 45 in a spaced relationship with the LED array, and has a plurality of separate areas 61, 62, 63.
Is defined on it. The plate 60 is formed of an optically transparent material such as glass, plastic, or crystal. Furthermore, the arrangement of the plate 60 is such that each LED of the LED array,
Specifically, in this embodiment, the light emitted from the LEDs 40, 41, 42 (represented by the arrow 65) is determined to be incident on different ones of the plurality of individual regions of the plate 60, respectively. A plurality of different phosphors 67, 68 are individually (ind) in different ones of the plurality of individual regions 61, 62 of the plate 60.
ividually) mounted and positioned to impinge light from different ones of the plurality of light emitting diodes 40, 41, respectively. Different phosphors 67 and 68 are LEDs
When the lights from 40 and 41 collide with each other, lights of different colors are generated.

In this particular embodiment, the phosphor 67 is an LED.
When properly energized to photons from the LED, phosphor 68 is selected to emit green light, and phosphor 68 is selected to emit red light when properly energized by photons from LED 41. Since the LEDs 40, 41, 42 are arranged to emit blue light, the area 63 of the plate 60 remains simply transparent so that the blue light passes directly through. Depending on the application, LEDs 40 and 41 may be replaced by LED 42 because conversion or secondary emission is not required to generate blue light.
It is also convenient to make the light finally emitted from the upper surface of the plate 60 approximately the same in each region 61, 62, 63 by making it somewhat larger (as shown in FIG. 5).

FIG. 6 shows a slightly different embodiment. Here, the optically transparent plate 60 is made of porous glass.
ass), biker mace, etc. The other elements are basically the same as those described in connection with FIG. 5 and will not be discussed further here. In this particular embodiment, the porous plate 70 is provided with a plurality of regions 7.
1, 72, 73 and a plurality of organic dyes (organic d
Yes), for example, put a green dye in the area 71,
A red dye is placed in area 72. Again, no dye is used in the area 73 and the transparent state remains, so that the corresponding LE
Note that the blue light from D passes directly through it without undergoing any conversion. For the purposes of this disclosure, organic dyes and all other materials that are excited to emit light by the incidence of photons are considered to be included in the definition of "phosphor".

Another different embodiment is shown in FIG. Here, the plate 60 is simply removed and a plurality of phosphor materials 75,
76 is placed directly on the surface of each LED (except one for emitting blue light). The remaining elements are basically the same as those described in connection with FIG. 5 and will not be discussed further here. This embodiment has the advantage that the number of elements is small, and can be manufactured more inexpensively and easily.

In each of the above-described embodiments, the LED array can be individually designated to form an image thereon (a
ddressable), generally arranged in rows and columns. Also, to form a full color image, each pixel of the image includes three LEDs, each corresponding to one of the three primary colors (ie, red, green and blue). I made some changes to the colors,
It will, of course, be understood that in some applications only two colors may be used to obtain substantially all colors. Referring to FIG.
One possibility of arranging an LED array in all color pixels has been shown. As an example, four full color pixels are shown,
The LEDs are denoted by R, G, B to indicate red, green and blue, respectively. It will be appreciated that the electrical connections to the various LEDs determine the exact function and pixel arrangement.

The LED array shown in FIG. 8 also shows the approximate dimensions of the LEDs and the spacing between them. For example, in this particular embodiment, the measured diameter X of each LED is about 20 microns and the center-to-center spacing S is less than about 40 microns. With this size and new multicolor concepts, for example, 1000 or 20 per column and row.
A full-color array containing 00 LEDs can be manufactured relatively easily.

Referring specifically to FIG. 9, an enlarged simplified cross-sectional view of an all color image display package 90 according to the present invention is shown. Package 90 includes a substrate 91 manufactured according to the previous description and having an LED array formed thereon, for example, similar to the structure shown in FIG. 5 or 6. A supporting or mounting substrate 92 is provided, which may be, for example, a silicon integrated circuit (IC) on which a driving circuit or the like is formed. The supporting substrate 92 also has an interconnect circuit 9 on its upper surface.
3 is formed, the LED array of the substrate 91 is mounted on the mounting substrate 9
2 integrated circuit. Multiple C4 type bumps
Bumps or epoxy adhesives 95 are used to attach plates 96 with phosphor regions (typically as described above) side by side to substrate 91 and illuminate them with a diode array. The bumps 95 are shown at the edges of the plate 96, but depending on the application it may be more convenient to form the higher ridges 57 (see FIG. 5) or place the mounting bumps thereon. As described above, a compact and convenient all-color image display package which is relatively easy to manufacture and use has been disclosed.

Referring to FIG. 10, another embodiment of an all color image display package 100 according to the present invention is shown.
The package 100 is manufactured according to the above description,
For example, an LED similar to the structure shown in FIG. 5 or FIG.
It includes a substrate 101 on which an array is formed. A supporting or mounting substrate 102 is provided, which may be, for example, a silicon integrated circuit (IC) on which a driving circuit or the like is formed. The supporting substrate 102 has a recess 103 formed in its upper surface, and the substrate 101 is mounted therein by a convenient means such as epoxy, bump bonding or the like.
Further, the supporting substrate 102 has an interconnection circuit 105 formed on the upper surface thereof, and connects the LED array of the substrate 101 to the integrated circuit of the mounting substrate 102. Interconnect circuits extend into the recess 103 and can be connected to the LED array by bump bonding within the recess. Alternatively, it may be connected directly to the contacts on the upper surface of the substrate 101 by wire bonding or by forming the connection after the substrate 101 is properly positioned.

Phosphor carrying plate
110 is mounted adjacent to the substrate 101 and over the LED array above it. One or more lenses 1
15 is mounted adjacent to the plate 110 and magnifies the image formed by the LED array to the extent that it can be fully perceived or understood by the operator. It will be appreciated that this embodiment may incorporate the structure shown in FIG. 7, in which case the plate 110 may be removed and the lens 115 simply placed on the LED array. Lens 115 is package 100
Included in a portable communication device (eg, telephone, pager, two-way radio, cellular telephone, etc.), data bank, small television, etc. Can be incorporated efficiently.

The embodiments of the image display device and the manufacturing method thereof have been disclosed above. Specifically, single color LED
A very simplified device has been disclosed that utilizes a. Due to the fact that a single color LED can be used to excite multiple colored phosphors,
The manufacturing process can be greatly simplified. Also,
The manufacturing process can be further simplified by the fact that LEDs can be utilized to excite multiple colored phosphors without the need for overly complex and large electron beam generators or lasers.

[Brief description of drawings]

FIG. 1 is a high-magnification simplified cross-sectional view of a raised or mesa type light emitting diode.

FIG. 2 is a highly enlarged simplified cross-sectional view of a planar light emitting diode.

FIG. 3 is a high-enlarged simplified cross-sectional view of a light-emitting diode using a separating absorption layer.

FIG. 4 is a graph showing the relationship between absorption and emission in a phosphor.

FIG. 5 is a highly enlarged simplified cross-sectional view showing a part of an embodiment of an all-color image display device according to the present invention.

FIG. 6 is a high-enlargement simplified sectional view showing a part of another embodiment of the all-color image display device according to the present invention.

FIG. 7 is a high-enlargement simplified sectional view showing a part of still another embodiment of the all-color image display device according to the present invention.

FIG. 8 shows a part of the image display device shown in FIG.
High magnification top view.

FIG. 9 is an enlarged simplified sectional view of an all-color image display package according to the present invention.

FIG. 10 is an enlarged simplified perspective view of another embodiment in which a lens system is incorporated in an all-color image display package according to the present invention.

[Explanation of symbols]

 15 light emitting diode (LED) 16 substrate 17 buffer layer 18 first ohmic layer 19 first cladding layer 20 active layer 21 second cladding layer 23, 24 electrical contact 25 high resistance region 27 raised portion 40, 41, 42 LED 46 First ohmic layer 47 First cladding layer 50 Active region 52 Second cladding layer 53 Second ohmic layer 55 High resistance region 57 Material layer 60 Plate 61, 62, 63 Separate region 67, 68 Phosphor 90 All color image display Package 91 Substrate 92 Mounting Substrate 95 Epoxy Adhesive 96 Plate 100 All Color Image Display Package 101 Substrate 102 Mounting Substrate 103 Recess 105 105 Interconnect Circuit 110 Phosphor Placement Plate 115 Lens

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Michael S. Levy North Lage Road, Apache Junction, Arizona, USA 30 (72) Inventor Ronald O. Petersen East Mountain, Phoenix, Arizona, USA・ Sage Drive 778

Claims (4)

[Claims] 1. An all-color image display device comprising: a substrate (4
5); a plurality of monochromatic light emitting diodes (40, 41, 42) formed on the substrate; a plurality of individual phosphors (67, 6) individually arranged with respect to the plurality of light emitting diodes.
8), wherein the light emitted from each of the plurality of light emitting diodes is arranged to be incident on a different one of the plurality of individual phosphors, and the light emitting diodes excite the plurality of individual phosphors. Said phosphors which, when collided with photons having sufficient energy, generate light of respectively different colors;
A display device, wherein each of the plurality of light emitting diodes emits a photon having sufficient energy to excite one of the plurality of individual phosphors when properly activated. . 2. An all-color image display device comprising: a substrate (4
5); a plurality of monochromatic light emitting diodes (40, 41, 42) formed on the substrate; an optically transparent plate (60) mounted side by side on the substrate, the plate including a plurality of individual Areas (61, 62, 63) are defined and the plate positioned so that light emitted by each of the plurality of light emitting diodes is incident on a different one of the plurality of individual areas of the plate; And a plurality of individual phosphors (67, 68) individually attached to the plate in different ones of the plurality of individual regions of the plate,
Light from different ones of the plurality of light emitting diodes are arranged to collide with each other, and when the light from the light emitting diodes collide, the phosphors each generate light of different colors; Display device. 3. An all-color image display device comprising: a substrate (4
5); an optically transparent plate (60) mounted side by side on said substrate, said plate comprising a plurality of regions (61, 6)
A plate (60) on which is formed a plurality of individual phosphors (67, 68) individually mounted in different ones of the plurality of individual regions of the plate. And a plurality of single color light emitting diodes formed on the substrate, wherein the phosphors each produce light of a different color upon collision with a photon having sufficient energy to excite the phosphor from the light emitting diode. (40, 41, 42)
Wherein photons emitted by each of the plurality of light emitting diodes are positioned to be incident on different ones of the plurality of discrete areas of the plate, each of which when properly biased: A display device comprising: a plurality of light emitting diodes emitting photons having sufficient energy to excite a plurality of different phosphors. 4. A method for manufacturing an all-color image display device comprising: preparing a substrate (45); forming light emitting diodes (40, 41, 42) on the substrate, The photons emitted by each of the light emitting diodes are separated by a plurality of discrete regions (6) in a plane spaced from the substrate.
1, 62, 63), each of which, when properly biased, emits a photon having sufficient energy to excite the phosphor to emit light. Forming a plurality of light emitting diodes; preparing an optically transparent plate (60) defining a plurality of individual regions (61, 62, 63); a plurality of individual phosphors (67, 68); Attaching to different ones of the individual regions of the plate, each of the individual phosphors producing a different color of light upon collision of a photon having sufficient energy to excite the phosphor. Attaching the phosphor to a substrate; and arranging the plate alongside the substrate, each phosphor in an individual region of the plate being located in one of the individual regions in the plate spaced from the substrate. To install Wherein the consisting of; floors.