JPH11174999A - Display device by semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device by a semiconductor laser capable of displaying large-sized full-color display by using a semiconductor laser element. SOLUTION: Light emitting sources 2l1 -2nm are formed by making a set of semiconductor laser elements 2R, 2G, 2B, emitting light beams of three primary colors, a unit and the light emitting sources 2l1 -2nm are arranged in a matrix shape. End face light emitting type elements are used for the semiconductor laser elements 2R, 2G, 2B and a large light emitting area and a prescribed wide angle of field are ensured by transmitting the laser beams emitted from the respective semiconductor laser element 2R, 2G, 2B through a diffuser plate 6 having the lens function.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using a semiconductor laser, and more particularly to an outdoor large full-color display device used in an advertising display tower, a ballpark, a stadium, and the like. And useful. 2. Description of the Related Art Liquid crystal, plasma emission, CRT, LED, FED, and the like have already been developed and commercialized as light sources for displays. On the other hand, with the development of semiconductor lasers in the visible region in recent years, high-brightness semiconductor lasers having the possibility of three primary colors are being developed. At present, a red laser whose center wavelength is around 630 nm is commercialized, but the remaining blue (around 470 nm) and green (5
As for the high-brightness semiconductor laser (20 nm), although the development of the crystal structure of the semiconductor laser is centered on the GaN-based and ZnSe-based semiconductor lasers, it is uncertain which material is appropriate for the wavelengths of the three primary colors. Here, a display device using a conventional laser oscillator except for a semiconductor laser as a light source applicable to a large display device outdoors as described above, and a display using a surface emitting semiconductor laser as a light source as a recent semiconductor laser. A device and a display device using an LED other than the laser will be described.
FIG. 8 is a configuration diagram of a display device using a laser oscillator excluding a semiconductor laser. As shown in the figure, the display device comprises a laser oscillator (including a solid and a liquid laser excluding a gas and a semiconductor laser) 19 emitting three primary colors and a scanning modulation mechanism 20 using a galvano mirror, a polygon mirror, an electro-optical element, or the like. Is scanned and projected on the screen plate 21 to visually check the image. FIGS. 9A and 9B are configuration diagrams of a display device that converts a wavelength of a semiconductor laser of one color to emit light of three primary colors. As shown in the figure, in the display device, different wavelength conversion elements 23 are respectively joined to a single-color semiconductor laser 22 to generate three primary colors 24a, 24b, and 24c of R, G, and B. It is configured to perform brightness adjustment. FIG. 10 is a configuration diagram of a display device using a surface emitting semiconductor laser as a light source. As shown in the figure, the display device is a surface emitting semiconductor laser 26 of three primary colors of R, G and B.
Are arranged on a two-dimensional plane. FIG. 11 shows a configuration example of the one element. As shown in the figure, a major feature of the device is the relationship between the structure of the semiconductor laser device and the laser oscillation direction. The laser beam 28 can be extracted in the thickness direction of a film called an active layer 27 for oscillating a laser. In addition, the spread angle of the laser light (beam) 28 is uniform and small. This type of display device includes the above-described FIGS.
In addition to the light emitting device shown in FIG. 1, there is a light emitting device using an LED element. The display device has LED elements arranged in a two-dimensional plane, and the element structure of the LED elements is basically the same as that of a semiconductor laser element. However, there are the following differences. That is, the semiconductor laser device uses a waveguide-type optical resonator that confines electrons and holes in a narrow region in order to increase the recombination probability of electrons and holes, and uses a waveguide type optical resonator that confines light in order to increase the stimulated emission probability. Light conversion efficiency is high, and high-luminance light can be extracted. [0008] Among the display devices according to the prior art as described above, the display device shown in FIG. 8 has a specific space for a laser oscillator 19, a scanning modulation mechanism 20 and a screen plate 21. Not only are individually required, but also have an inherent disadvantage that the luminance is low as a large outdoor high-brightness full-color display device. The display device shown in FIG.
Unlike the display device shown in (1), the light source unit itself is integrated with the image display panel, and it can be made thinner and more compact. There is a practical problem that it is difficult to adjust the temperature phase and the angle phase matching of the element. When the display device shown in FIG. 10 is used as a large outdoor high-brightness full-color display device, it is necessary to enlarge the viewing angle of the display panel, and the viewing angle at this time is vertically and horizontally. Not the same, FIG.
As shown in (a), 60 ° the upper and lower viewing angle theta _x, wide viewing angle, such as that the viewing angle theta _Y of the left and right 120 ° or more is required. By the way, as shown in FIG. 13, since the diameter of the light emitting surface of the surface emitting semiconductor laser is at most about several hundred μm, when applied to a large outdoor high-brightness full-color display device, the area of the pixel is very small. And can be recognized only as point light sources 28R, 28G, 28B. For this reason, the entire display panel cannot be filled as pixels, resulting in a display panel with poor image quality. In a display device using an LED element as a light-emitting element, there is a practical problem that the viewing angle and the brightness are small and the operating cost is high when used as a large outdoor high-brightness full-color display device. FIG. 14 is a graph showing output characteristics of the semiconductor laser device and the LED device with respect to drive current. As shown in the figure, since the semiconductor laser has a resonance structure at both end faces of the active layer, when the driving current exceeds the threshold value, light with high efficiency and high luminance can be obtained by the light amplifying action by stimulated emission. An object of the present invention is to provide a display device using a semiconductor laser capable of performing a large-size full-color display using a semiconductor laser device in view of the above-mentioned prior art. The present invention that achieves the above object has the following features. 1) A light emitting source is formed as a single unit using a set of semiconductor laser elements that emit red, green and blue primary colors, and a large number of such light emitting sources are arranged in a matrix to form a two-dimensional display surface. In a display device using a semiconductor laser to be formed, the above-mentioned semiconductor laser element is of an edge-emitting type, and the light-emitting surface for emitting the laser light is disposed in parallel with the display surface, and the light-emitting surfaces of all the semiconductor laser elements are arranged. So that the laser light emitted from is incident on the display surface at right angles,
Further, at least a portion of the display surface through which the laser light is transmitted is formed of a diffusion plate having a lens function. According to the present invention, the laser light emitted from each semiconductor laser element is diffused by the diffusion plate to enlarge the pixel area, and a desired wide viewing angle is obtained by the lens function of the diffusion plate. 2) In the above 1), each semiconductor laser element is so arranged that the larger dimension of the horizontal direction and the vertical direction of the display device is the thickness direction of the light emitting surface which is the active layer of each semiconductor laser element. Arranged. According to the present invention, the diffusion angle of the laser beam emitted from each semiconductor laser element differs between the film thickness direction and the film width direction, and the diffusion angle in the film thickness direction is larger than the diffusion angle in the film width direction. Since it is large, the viewing angle in the horizontal direction and the viewing angle in the vertical direction of the display device are different. 3) A light emitting source is formed as a single unit using a set of semiconductor laser elements that emit red, green and blue primary colors, and a large number of such light emitting sources are arranged in a matrix to form a two-dimensional display surface. In the display device using the formed semiconductor laser, the semiconductor laser element is of an edge-emitting type, and the light-emitting surface emitting the laser light is disposed so that the film thickness direction is perpendicular to the display surface. The laser light emitted from the light emitting surface of the laser element is reflected by the reflecting means so that the laser light is incident on the display surface at a right angle, and the display surface has a linear shape in contact with one electrode of each semiconductor laser element. It has electrodes and at least a portion through which laser light is transmitted is formed of a diffusion plate having a lens function. According to the present invention, the laser light emitted from each semiconductor laser element is reflected by the reflecting means and is incident on the display surface at a right angle, and the pixel area is enlarged by the diffusion function of the diffusion plate. Corners are secured. 4) In the above 3), a prism is provided instead of the reflecting means. According to the present invention, the same effect as the invention described in the above 3) can be obtained. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view conceptually showing the entire display device according to the embodiment of the present invention. As shown in the figure, in the display device, a light emitting source 2 having a semiconductor laser element of three primary colors (R, G, B) as one unit is arranged in a matrix inside a frame 1 having a width W and a height H. A two-dimensional display surface is formed, and the driving unit 3 controls light emission of the light emitting source 2. FIG. 2 is an internal structural diagram showing details of the inside of the display device. As shown in the figure, the display device has n rows and m columns arranged in a matrix on a driving substrate 4.
It has × m light-emitting sources 2 ₁₁ to 2 _nm . Each light source 2 ₁₁
２2 _nm corresponds to one semiconductor laser element 2 _R , 2 _G , 2 _B that generates laser light corresponding to each wavelength of the three primary colors (R, G, B).
It is configured as individual units. Each of the semiconductor laser elements 2 _R , 2 _G , 2 _B is connected to a specific semiconductor laser element 2 _R , 2 _G via a linear electrode 5 a linearly formed along one direction on a planar driving substrate 4. , 2 trigger signal for driving the _B is supplied, similarly along the other direction orthogonal linearly formed in linear electrode 5b, the current for light emission through 5c is fed in the one direction You. The semiconductor laser elements 2 _R , 2 _G , and 2 _B are of an edge-emitting type having a slit-shaped light emitting surface at the center of the upper surface in FIG. 2, and all the light emitting surfaces are opposed to each other. The diffusion plate 6 is disposed so as to perform the operation. The diffusion plate 6 becomes a display surface of the display device. FIG. 3 shows the semiconductor laser devices 2 _R , 2 _G and 2 _B
(A), a perspective view (b), and a cross-sectional view (c) shown together with the diffuser plate 6 showing only one of them. FIG.
As shown in FIG. 7, the semiconductor laser elements 2 _R , 2 _G , and 2 _B are disposed on the driving substrate 4 with the back surface opposite to the light emitting surface 2 c in contact with the driving substrate 4. Each of the linear electrodes 5b and 5c formed on the driving substrate 4 is
a and 2b are connected by brazing 7a and 7b. The laser beam emitted from the light emitting surface 2c, which is the active layer of each of the semiconductor laser elements 2 _R , 2 _G , and 2 _B , has a different diffusion angle in the film thickness direction and the film width direction. That is, as shown in FIG. 3B, the diffusion angle θ ₁ in the film thickness direction is larger than the diffusion angle θ _{2 in the} film width direction. On the other hand, the size of the display device in the horizontal direction (X direction in FIG. 3B; the same applies hereinafter) is larger than the size in the vertical direction (Y direction in FIG. 3B; the same applies hereinafter). Therefore, the semiconductor laser devices 2 _R , 2 _R
G, 2 _B is the thickness direction is the X direction, the film width direction are arranged such that the Y-direction. Further, the semiconductor laser elements 2 _R , 2 _R
G, 2 large size of the emitting surface 2c of the _B number be 100μm
Therefore, it can be recognized only as a point light source as it is. Therefore, as shown in FIG. 3C, the light emitting area is enlarged by passing the light through the diffusion plate 6 to improve the image quality by enlarging the entire pixel area of the display device, and at the same time, the laser of the diffusion plate 6 is improved. By adding a lens function to a portion through which light passes, a display device having a wide viewing angle according to the purpose can be configured. That is, the semiconductor laser element 2 _R , which is a point light source as shown in FIG.
(2 _G , 2 _B ) becomes a light source having a wide light emitting area 8 as shown in FIG. 4B, and the semiconductor laser element 2 _R as a whole is a set of point light sources as shown in FIG. , 2
By a set of _G, 2 _B, it may constitute a light emitting source having a wide range of light emitting area 8 as shown in FIG. (D). Thus, as shown in FIG. 5, a display device having a viewing angle of, for example, 120 ° in the X direction and 60 ° in the Y direction is configured. According to this embodiment, the laser light emitted from each of the semiconductor laser elements 2 _R , 2 _G , and 2 _B is diffused by the diffusion plate 6 to enlarge the pixel area, and the lens function of the diffusion plate 6 is used. A desired wide viewing angle can be secured. FIG. 6 is a cross-sectional view showing one of the semiconductor laser devices 2 _R , 2 _G , and 2 _{B according} to another embodiment of the present invention, together with the vicinity thereof. As shown in the figure, the semiconductor laser elements 2 _R , 2 _G and 2 _B themselves are the same as those according to the above-described embodiment, and similarly to the above-described embodiment, each of the semiconductor laser elements 2 _R , 2 _G and 2 _{B 2B} is a set of units arranged in a matrix on a two-dimensional plane. In this embodiment, the semiconductor laser elements 2 _R , 2 _R
G, and 2 _B is the thickness direction of the light emitting surface 2c are disposed on the driving substrate 4 so as to be perpendicular to the glass substrate 9 which is a display surface. That is, it is inverted by 90 ° with respect to the above embodiment. One linear electrode 5c for supplying current is printed and formed on the glass substrate 9, and this linear electrode 5c
To one of the electrode portions 2 of the semiconductor laser elements 2 _R , 2 _G and 2 _B
The semiconductor laser elements 2 _R , 2 _G , and 2 _B are sandwiched between the glass substrate 9 and the driving substrate 4 so as to be in contact with the substrate b. The other linear electrodes 5b for current supply Yes formed on the driving substrate 4, similarly by brazing 7a with the embodiment to the other electrode portion 2a of the semiconductor laser element 2 _R, 2 _G, 2 _B Connected. As described above, in this embodiment, laser light is emitted from the semiconductor laser elements 2 _R , 2 _G , and 2 _{B in} a direction parallel to the surface of the glass substrate 9 (horizontal direction in the figure). It is necessary to change the direction perpendicular to the surface of No. 9. Therefore, the semiconductor laser devices 2 _R , 2 _G , 2
_A reflecting plate 10 is disposed opposite to the light emitting surface 2c of _B , and the laser beams emitted from the semiconductor laser elements _2R , _2G , and 2B are incident on the glass substrate 9 at right angles. is there. The portion of the glass substrate 9 through which the laser light is transmitted is formed as a concave lens 11 for adjusting the viewing angle and as a diffusion plate for expanding the pixel area. Further, a non-reflective coating layer is formed on the inner surface of the portion of the glass substrate 9 through which the laser light is transmitted, and the non-reflective coating layer allows the laser light to efficiently transmit through the glass substrate 9 without being reflected by the glass substrate 9. It is devised so that it can be used effectively for display. According to the present embodiment, the semiconductor laser device 2
_R, 2 _G, the laser beam 2 _B is emitted is incident perpendicularly to the concave lens 11 of the glass substrate 9 is reflected by the reflection plate 10. Since the concave lens 11 is formed by a diffusion plate, the pixel area is enlarged by the diffusion function of the diffusion plate, and at the same time, a predetermined wide viewing angle is secured by the concave lens 11. Note that a prism 12 may be used instead of the reflecting plate 10 in the embodiment shown in FIG. 6, as shown in FIG. This embodiment has exactly the same operation as that shown in FIG. As described in detail with the above embodiments, the invention described in [Claim 1] is an embodiment in which a set of semiconductor laser elements emitting three primary colors of red, green and blue is formed as one unit. In a display device using a semiconductor laser in which a light emitting source is formed and a large number of the light emitting sources are arranged in a matrix to form a two-dimensional display surface, the semiconductor laser element is an edge emitting type, The light emitting surface that emits light is disposed so as to be parallel to the display surface so that laser light emitted from the light emitting surfaces of all the semiconductor laser elements is incident on the display surface at a right angle. Since the transmitting portion is formed by a diffusion plate having a lens function, the laser light emitted from each semiconductor laser element is diffused by the diffusion plate to enlarge the pixel area, and has a diffusion plate. The desired wide viewing angle is obtained by the lens function. As a result, the light emitting area of the display surface can be increased, and a full-color display device having a desired wide viewing angle can be configured using the semiconductor laser element. According to a second aspect of the present invention, in the first aspect of the present invention, the active layer of each semiconductor laser element has a larger dimension in the horizontal and vertical directions of the display device. Since each semiconductor laser element is disposed so as to be in the film thickness direction of the light emitting surface, the diffusion angle of the laser beam emitted from each semiconductor laser element is different between the film thickness direction and the film width direction, The diffusion angle is larger than the diffusion angle in the film width direction. As a result, a display device having a relatively large viewing angle in the horizontal direction and a relatively small viewing angle in the vertical direction is optimal. According to a third aspect of the present invention, a light emitting source is formed as a unit using a set of semiconductor laser elements that emit red, green and blue primary colors, and a large number of such light emitting sources are arranged in a matrix. In a display device using a semiconductor laser in which a two-dimensional display surface is formed and the semiconductor laser element is of an edge emitting type, the thickness direction of a light emitting surface for emitting the laser light is perpendicular to the display surface. And the laser light emitted from the light emitting surfaces of all the semiconductor laser elements is reflected by the reflecting means so that the laser light is incident on the display surface at a right angle. It has a linear electrode in contact with one of the electrode portions, and at least a portion through which the laser light is transmitted is formed by a diffusion plate having a lens function. With light is incident perpendicular to the display surface is reflected by the reflecting means, the pixel area is enlarged by the diffusion function of the diffusion plate. Accordingly, the same effects as those of the invention described in claim 1 can be obtained. further,
Since one electrode portion of the semiconductor laser element is brought into contact with a linear electrode formed on a glass substrate serving as a display surface, electrical connection between the electrode portion and the linear electrode portion can be secured.
The connection structure between the two can be simplified. In the invention described in [Claim 4], since a prism is provided instead of the reflecting means in the invention described in [Claim 3], the same as the invention described in [Claim 3] is provided. It works.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram conceptually showing the entire display device according to an embodiment of the present invention. FIG. 2 is an internal structural diagram showing details of the inside of the display device shown in FIG. 1; FIGS. 3A and 3B are a sectional view (a), a perspective view (b), and a sectional view (c) together with a diffuser plate, respectively, showing one of the semiconductor laser elements. FIG. 4 is an explanatory view conceptually showing point light sources (a) and (c) and enlarged light emitting areas (b) and (d). FIG. 5 is an explanatory diagram conceptually showing the outer shape of the display device according to the embodiment of the present invention. FIG. 6 is a cross-sectional view showing one of the semiconductor laser devices according to another embodiment of the present invention, which is shown together with its vicinity. FIG. 7 is a sectional view showing a modification of the embodiment shown in FIG. 6; FIG. 8 is a configuration diagram of a display device using a laser oscillator excluding a semiconductor laser. FIG. 9 is a configuration diagram of a display device that emits light of three primary colors by converting the wavelength of a semiconductor laser of one color. FIG. 10 is a configuration diagram of a display device using a surface emitting semiconductor laser as a light source. 11 is a structural diagram illustrating a configuration example of one element included in the display device illustrated in FIG. 10; 12 is an explanatory view conceptually showing a viewing angle of the display device shown in FIG. 10, in which (a) relates to a vertical direction and (b) relates to a horizontal direction. FIG. 13 is an explanatory view conceptually showing a case where a light emitting surface of a display device is formed by a surface emitting semiconductor laser. FIG. 14 is a graph showing output characteristics of a semiconductor laser element and an LED element with respect to drive current. [Description of Signs] 2 Light-emitting sources 2 _R , 2 _G , 2 _B Semiconductor laser elements 2 a, 2 b Electrodes 2 c Light-emitting surface 4 Drive electrodes 5 a, 5 b, 5 c Linear electrodes 6 Diffusion plates 7 a, 7 b Brazing 9 Glass substrate 10 Reflector 11 Concave lens 12 Prism

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yoshito Soma             1-1-1 Wadazakicho, Hyogo-ku, Kobe City, Hyogo Prefecture             No.Mitsubishi Heavy Industries, Ltd.Kobe Shipyard

Claims (1)

Claims: 1. A light emitting source is formed as a unit of a set of semiconductor laser elements that emit red, green and blue primary colors, and a large number of such light emitting sources are arranged in a matrix. 2
In a display device using a semiconductor laser forming a two-dimensional display surface, the semiconductor laser element is of an edge-emitting type, and all the semiconductor lasers are arranged such that a light-emitting surface for emitting laser light is parallel to the display surface. A semiconductor laser wherein laser light emitted from a light emitting surface of a laser element is incident on a display surface at a right angle, and at least a portion of the display surface through which the laser light is transmitted is formed of a diffusion plate having a lens function. Display device. 2. The semiconductor laser device according to claim 1, wherein the larger dimension of the horizontal direction and the vertical direction of the display device is the thickness direction of the light emitting surface that is the active layer of each semiconductor laser element. A display device using a semiconductor laser, comprising a device. 3. A light-emitting source is formed as a single unit using a set of semiconductor laser elements that emit red, green, and blue primary colors, and a large number of such light-emitting sources are arranged in a matrix.
In a display device using a semiconductor laser having a two-dimensional display surface, the semiconductor laser element is of an edge-emitting type, and is disposed such that a thickness direction of a light emitting surface that emits the laser light is perpendicular to the display surface. At the same time, the laser light emitted from the light emitting surfaces of all the semiconductor laser elements is reflected by the reflection means so that the laser light is incident on the display surface at a right angle. A display device using a semiconductor laser, comprising: a linear electrode in contact with the substrate; and at least a portion through which laser light is transmitted is formed of a diffusion plate having a lens function. 4. A display device according to claim 3, wherein a prism is provided in place of the reflection means.