1. Field of the Invention
The present invention generally relates to a light-emitting device, in particular, to an electron emission light-emitting device and applications thereof.
2. Description of Related Art
Currently, mass-produced light source apparatus or display apparatus mainly employ two types of light-emitting structures, which are described as follows.
However, the above two types of light-emitting structures have disadvantages. For example, the attenuation occurs after the irradiation of the UV lights, so that specific requirements must be taken into account in selecting the material in the gas-discharge light source. Moreover, the gas-discharge light-emitting mechanism emits the visible lights through two processes, so that more energy is consumed, and if the plasma must be generated in the process, more electricity is consumed. On the other hand, the field emission light source requires a uniform electron emitter to be grown or coated on the cathode, but the mass production technique of this type of cathode structure is not mature, and the uniformity and a poor production yield of the electron emitter are still bottlenecks. Further, a distance between the cathode and the anode of the field emission light source must be accurately controlled, and the ultra high vacuum packaging is quite difficult and also increases the fabrication cost.
Accordingly, the present invention is directed to a display pixel structure having good light-emitting efficiency and easy to fabricate, which is constituted by an electron emission light-emitting device.
The present invention is further directed to a display apparatus, which uses the electron emission light-emitting device to serve as the display pixel, so as to provide a good display quality, and to reduce cost and complexity in fabrication.
As embodied and broadly described herein, a pixel structure of a display apparatus is provided, which includes a first substrate and a second substrate. A plurality of cathode structure layers is disposed on the first substrate. The second substrate is made of a light-transmissive material. A plurality of anode structure layers is disposed on the second substrate, and the anode structure is made of a light-transmissive conductive material. The first substrate faces to the second substrate, such that the cathode structure layers are respectively aligned with the anode structure layers. A separation structure is disposed between the first substrate and the second substrate, for respectively partitioning the anode structure layers and the cathode structure layers to form a plurality of spaces. A plurality of fluorescent layers is respectively disposed between the anode structure layers and the cathode structure layers. A low-pressure gas is filled in the spaces. The low-pressure gas layer has an electron mean free path, allowing at least sufficient amount of electrons to directly impinge the fluorescent layers under an operation voltage.
Further, the present invention further provides a display apparatus including a plurality of display pixels arranged in an array. Each display pixel includes an electron emission light-emitting device. The electron emission light-emitting device includes a cathode structure layer; an anode structure layer; a fluorescent layer disposed between the cathode structure layer and the anode structure layer; and a low-pressure gas disposed between the cathode and the anode, for inducing the cathode to emit a plurality of electrons uniformly. The low-pressure gas has an electron mean free path, allowing at least sufficient amount of electrons to directly impinge the fluorescent layer under an operation voltage.
The present invention further provides a display apparatus, which includes a first substrate and a second substrate. A plurality of cathode structure layers is disposed on the first substrate, so as to form a two-dimensional array. The second substrate is made of a light-transmissive material. A plurality of anode structure layers is disposed on the second substrate, and the anode structure layer is made of a light-transmissive conductive material. The first substrate faces to the second substrate, such that the cathode structure layers are respectively aligned with the anode structure layers. A separation structure is disposed between the first substrate and the second substrate, for respectively partitioning the anode structure layers and the cathode structure layers to a plurality of spaces. A plurality of fluorescent layers is respectively disposed between the anode structure layers and the cathode structure layers. A low-pressure gas is filled in the spaces, and the low-pressure gas layer has an electron mean free path, allowing at least sufficient amount of electrons to directly impinge the fluorescent layer under an operation voltage. A plurality of drive units is disposed on at least one of the first substrate and the second substrate, for controlling the pixels of the two-dimensional array, so as to apply the corresponding operation voltage to generate luminance gray-levels.
In view of the above, the present invention uses a thin gas to easily induce electrons from the cathode, thus avoiding possible problems resulting from fabricating the electron emitter on the cathode. Moreover, as the gas is thin, the electrons have a large mean free path allowing most electrons to directly react with the fluorescent layer to emit light before colliding the gas, and this process does not cause the glow discharge. In other words, the electron emission light-emitting device of the present invention has a higher light emitting efficiency, is easy to fabricate, and has a better production yield.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The electron emission light-emitting device provided by the present invention has the advantages of the conventional gas-discharge light source and field emission light source, and overcomes the disadvantages of the above two conventional light-emitting structures. Referring to
Different from the above two conventional light-emitting mechanisms, the electron emission light-emitting device of the present invention uses a thin gas instead of the electron emitter to easily induce the electrons from the cathode, such that the electrons directly react with the fluorescent layer to emit light rays.
Comparing with the conventional gas glow discharge light source, the amount of the gas filled in the electron emission light-emitting device of the present invention is only required to be enough for inducing the electrons from the cathode and do not generate the glow discharge, while light rays are not generated by using UV lights to irradiate the fluorescent layer. Therefore, the attenuation of the material in the device caused by the irradiation of the UV lights will not occur. Experiments and theories verify that that the gas in the electron emission light-emitting device of the present invention is thin, and thus the mean free path of the electrons can be up to about 5 mm or above. In other words, most electrons directly impinge the fluorescent layer to emit light rays before impinging the gas molecules. Moreover, the electron emission light-emitting device of the present invention does not need to generate light rays through two processes, thus having higher light emitting efficiency and reducing the power consumption.
On the other hand, the conventional field emission light source requires forming the microstructure serving as the electron emitter on the cathode, and the microstructure is difficult to control in mass production process. The most common microstructure is carbon nanotube, but when coated on the cathode, problems of different tube lengths and gathering into clusters are generated, and thus a light emitting surface has dark spots and the light emission uniformity is unsatisfactory, which are the technical bottlenecks and main costs of the field emission light source. The electron emission light-emitting device of the present invention is capable of inducing the electrons uniformly from the cathode by the use of gas, and only a simple cathode planar structure is used to achieve 75% light emission uniformity for an electron emission light-emitting panel, thus solving the bottleneck of the conventional field emission light-emitting apparatus that the light emission uniformity is difficult to improve. Therefore, the fabrication cost can be significantly saved, and the process is simpler. Moreover, the electron emission light-emitting device of the present invention is filled with the thin gas, so the ultra high vacuum environment is not required, thus avoiding the difficulties encountered during the ultra high vacuum packaging. Furthermore, the experiment results show that the electron emission light-emitting device of the present invention can reduce a turn on voltage to about 0.4 V/μm with the help of the gas, which is much lower than the turn on voltage of up to 1-3 V/μm of the common field emission light source.
Further, based on the Child-Langmuir equation, after substituting the practical relevant data of the electron emission light-emitting device of the present invention into the equation, it can be calculated that the distribution of a dark region of the cathode of the electron emission light-emitting device of the present invention ranges from about 10 cm to 25 cm, which is much greater than the distance between the anode and the cathode. In other words, the electron emission light-emitting device of the present invention uses the gas to induce the electrons of the cathode, and the electrons directly react with the fluorescent layer to emit lights.
In this embodiment, the fluorescent layer 240 is, for example, coated on a surface of the anode 210. In addition, the anode 210 is, for example, made of a light-transmissive conductive oxide (TCO), such that the lights L pass through the anode 210 and emerge from the electron emission light-emitting device 200. The light-transmissive conductive oxide may be a common material, for example, selected from indium tin oxide (ITO), F-doped tin oxide (FTO), or indium zinc oxide (IZO). Definitely, in other embodiments, the anode 210 or the cathode 220 may also be made of a metal or other materials with good conductivity.
The gas 230 used in the present invention may be an inert gas such as N2, He, Ne, Ar, Kr, Xe, or a gas such as H2 and CO2 having good conductivity after ionization, or a common gas such as O2 and air. In addition, by selecting the type of the fluorescent layer 240, the electron emission light-emitting device 200 can emit different types of lights, such as visible lights, infrared lights, or UV lights.
In addition to the embodiment in
Further, the present invention can form a structure similar to the electron emitter of the field emission light source on the anode or the cathode or both, so as to reduce the working voltage on the electrode to generate electrons more easily.
Referring to
An electron emission light-emitting device 400b in
The various electron emission light-emitting devices 400a, 400b, or 400c having the induced discharge structure(s) 452 and/or 454 may be integrated with the design of the secondary electron source material layer 322 as shown in
The electron emission light-emitting devices serving as light-emitting structures provided by the present invention may have different forms.
The description of other devices is illustrated in the above embodiments and will not be described herein again.
It should be noted that the light-emitting structure of
The electron emission light-emitting device of the present invention may be used to fabricate a light source apparatus, which is composed of, for example, any type of electron emission light-emitting device in the above several embodiments, so as to provide a light source.
Definitely, various electron emission light-emitting devices mentioned above may also be applied in a display apparatus.
The pixel structure designed by the above mentioned technology may include, for example, a first substrate 1000 and a second substrate 1002. A plurality of cathode structure layers 1004 is disposed on the first substrate 1000. The second substrate 1002 is made of a light-transmissive material. A plurality of anode structure layers 1010 is disposed on the second substrate 1000, in which the anode structure 1010 is made of a light-transmissive conductive material. The first substrate 1000 faces to the second substrate 1002, such that cathode structure layers 1004 are respectively aligned with the anode structure layers 1010. A separation structure 1012 is disposed between the first substrate 1000 and the second substrate 1002, for respectively partitioning the anode structure layers 1010 and the cathode structure layers 1004 to form a plurality of spaces. A plurality of fluorescent layers 1008a, 1008b, 1008c are respectively located between the anode structure layers 1010 and the cathode structure layers 1004. A low-pressure gas 1006 is filled in the spaces. The low-pressure gas 1006 has an electron mean free path, allowing at least sufficient amount of electrons to directly impinge the fluorescent layers 1008a, 1008b, 1008c under an operation voltage.
Herein, the fluorescent layer 1008a, the fluorescent layer 1008b, and the fluorescent layer 1008c are, for example, respectively made of different materials, and are excited to emit red, green, and blue lights. The gas pressure values of gas of the pixels may be identical or different from one another, which vary depending on the design and practical operation. Definitely, if the display is only required to display a single color, the material of the fluorescent layer may have a different arrangement.
Images are displayed by the variations of the luminance gray-level, and the required color is determined by relative luminance gray-levels of red, green, and blue lights. Therefore, the gray-level of each pixel needs to be adjusted by some mechanisms.
Based on the reaction of the gas, under the selected gas pressure value, the relationship between the practically applied voltage and the gray-level may be obtained to serve as the data for calibrating the gray-level.
For example, the three pixels, i.e., red, green, and blue pixels of
As for a passive driving mechanism, for example, a time division mechanism, scan lines are displayed sequentially in a frame unit of the scan lines. As human eyes have visual persistence, the image may be formed by displaying all the scan lines in sequence in a certain time. Herein, a time difference still exists between the first scan line and the last scan line, so in order to adjust the brightness difference, the brightness of first scan line is set to be higher and the brightness of the rest scan lines descends sequentially.
The above driving mechanism is driven in a passive mode. In addition, the driving mechanism may also be driven in an active mode. Referring to
The details of the above driving mechanism are known to those of ordinary skill in the art, and details of the practical designs adopting the pixel structure and light emitting mechanism of the present invention will not be described herein.
In addition, the above embodiments may be combined to form different applications and variations depending on practical design requirements.
In view of the above, the electron emission light-emitting device provided by the present invention and the light source apparatus and display apparatus using the device have characteristics of power-saving, high light-emitting efficiency, short response time, easy to fabricate, and environmental-friendly (mercury free), thus providing another option of the light source apparatus and display apparatus on the market. As compared with the conventional light-emitting structure, the electron emission light-emitting device provided by the present invention has a simple structure, in which the cathode as long as being a planar structure can operate normally, and the related secondary electron source material layer or induced discharge structure is optional and not essential devices. Further, the electron emission light-emitting device of the present invention does not need the ultra high vacuum packaging, thus simplifying the production process and facilitating the mass production.
On the other hand, the cathode of the electron emission light-emitting device of the present invention may be a metal, so the reflectivity is improved and the brightness and light-emitting efficiency are also improved. Moreover, the wavelengths of the lights emitted by the electron emission light-emitting device vary depending on the types of the fluorescent layers, and the light sources of different wavelength ranges may be designed depending to different usages of the light source apparatus or the display apparatus. In addition, the electron emission light-emitting device of the present invention may be designed into a planar light source, a linear light source, or a spot light source, so as to meet different usage requirements of the display apparatus and the light source apparatus (e.g., backlight modules or illumination lamps).
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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95147427 A | Dec 2006 | TW | national |
96128668 A | Aug 2007 | TW | national |
This application is a continuation-in-part of a prior U.S. application Ser. No. 11/674,159, filed on Feb. 13, 2007, and also claims the priority benefit of Taiwan application serial no. 96128668, filed on Aug. 3, 2007. The U.S. application Ser. No. 11/674,159 claims the priority benefit of Taiwan application serial no. 95147427, filed on Dec. 18, 2006. The entirety of each of the above-mentioned patent applications is incorporated herein by reference and made a part of this specification.
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Number | Date | Country | |
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Number | Date | Country | |
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Parent | 11674159 | Feb 2007 | US |
Child | 11958393 | US |