1. Field of the Invention
The present invention generally relates to a planar light source apparatus applicable to a liquid crystal backlight module.
2. Description of Related Art
Light source apparatuses are widely used in the daily life. The conventional light source apparatuses such as light bulbs produce a visible light source by passing a current through filaments to heat up. The light bulbs are generally spot light sources. Later, the tube light source is developed. After a long term development and modification, planar light source devices are put forth and widely used in planar displays.
Light source may be produced through many mechanisms.
Another light source generating mechanism is the field emission mechanism as shown in
The above two conventional light-emitting mechanisms have respective advantages and disadvantages. The gas discharge manner is easy and the structure is simple, but the plasma is generated in the process, thus consuming energy. The field emission light source is a kind of cold light source and has a similar principle like the cathode ray tube (CRT) wherein the electrons escape from the cathode under the high electric field between the cathode and the anode and then hit the phosphors coated on the anode to emit light. The field emission light source is advantageous in high brightness and power saving, and is easy to be made into a planar structure. However, the field emission light source has the disadvantages that the emission material needs a spindle structure or carbon nanotube to grow or be uniformly coated on the cathode. This planar fluorescent lamp must use a support to separate the cathode and the anode, and the vertical distance between the cathode and the anode must be adjusted carefully. Since the tolerance is small, the cost of the structure design and the yield must be taken into account in mass application, and the uniformity of the overall light brightness is difficult to control. Moreover, the vacuum packaging is also a problem.
The present invention is directed to a light source apparatus, which is easy to be fabricated into a planar light source without requiring a high vacuum degree, has a better brightness and luminous efficiency, and can operate under a lower operating voltage.
The present invention is directed to a backlight source module, which is realized by the light source apparatus.
The present invention provides a light source apparatus, which includes a cathode structure with a light transmission property serving as a light-emitting surface, an anode structure with a light reflectivity located opposite to the cathode structure, a fluorescent layer located between the cathode structure and the anode structure, and a low-pressure gas layer filled between the cathode structure and the anode structure. The low-pressure gas layer functions to induce the cathode to uniformly emit electrons, and has a large electron mean free path allowing electrons to directly hit the fluorescent layer under an operating voltage, so as to generate desired lights.
The present invention is also directed to a light source apparatus, which includes a cathode structure with a light transmission property, an anode structure with a light transmission reflectivity located opposite to the cathode structure, a discharge layer located on at least one of the cathode structure and the anode structure, a fluorescent layer located between the cathode structure and the anode structure, and a low-pressure gas layer filled between the cathode structure and the anode structure. The low-pressure gas layer functions to induce the cathode to uniformly emit electrons, and has a large electron mean free path allowing electrons to hit the fluorescent layer directly under an operating voltage.
The present invention is also directed to a backlight source apparatus, which includes at least one power controller for providing at least one operating voltage, and a light emitting unit including at least one light emitting panel controlled by the operating voltage. The light emitting panel includes a cathode structure, an anode structure located opposite to the cathode structure, a fluorescent layer located between the cathode structure and the anode structure, and a low-pressure gas layer filled between the cathode structure and the anode structure. The low-pressure gas layer functions to induce the cathode to uniformly emit electrons, and has a large electron mean free path allowing electrons to directly hit the fluorescent layer under an operating voltage.
In order to make the aforementioned and other objectives, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
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 preferred 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.
Hereinafter, some embodiments are described for illustrating the features of the present invention, and will not intended to limit the scope of the present invention.
The material of the cathode structure 302a is a glass substrate with a metal layer or a transparent conductive material evaporated thereon. The anode structure 304a is located opposite to the cathode structure 302a. The anode structure 304a is a light transmissive structure, and the material thereof is an indium-tin-oxide (ITO), a fluorin-doped tin oxide (FTO), or another transparent conductive oxide (TCO) material. The cathode structure 302a and the anode structure 304a basically include, for example, a substrate and an electrode layer on the substrate. The actual structure of the cathode structure 302a and the anode structure 304a may vary depending on actual design, which is apparent to those of ordinary skill in the art, and will not be described herein.
The fluorescent layer 306 is disposed between the cathode structure 302a and the anode structure 304a, and is generally disposed on, for example, the anode structure 304a.
The secondary electron generation layer 308 is disposed on the cathode structure 302a. The material of the secondary electron generation layer 308 may be MgO, Tb2O3, La2O3, or CeO2.
The low-pressure gas layer 310 is disposed between the cathode structure 302 and the anode structure 304, in which a low-pressure gas in a range of 10 to 10−3 torr for enabling the electron mean free path to be approximately the distance between cathode and anode.
In an embodiment, the light source apparatus in
In the embodiment of the present invention, a thin gas is used to easily induce enough electrons 320 uniformly. A field emission mechanism is used to allow the ionized electrons 320 to hit the fluorescent layer 306, so as to generate desired lights. Since the ionized positive ions 322 in the gas may hit the secondary electron generation layer 308, additional secondary electrons 324 may be generated to hit the fluorescent layer 306 when the positive ions hit the secondary electron generation layer 308, thus improving the luminous efficiency.
In this embodiment, the anode structure 304a is a light transmissive structure, when the electrons 320 hit the fluorescent layer 306, the generated lights 330 pass through the anode structure 304a. This light source apparatus is also referred to as a transmissive light source apparatus. Moreover, in the transmissive light source apparatus, the cathode structure 302a may be a high-reflective metal capable of improving the reflectivity and increasing the brightness and luminous efficiency.
It should be noted that since the filled gas is used to induce the cathode to uniformly emit electrons, the selected gas is not particularly restricted, and may be any gas or gas mixture, for example, atmospheric air, He, Ne, Ar, Kr, Xe, H2, or CO2. Since the filled gas has a low or medium vacuum degree, the electron mean free path is large enough to allow the electrons to directly hit the material of the fluorescent layer 306 in the electric field, so as to emit desired lights.
The embodiment of
The light source apparatus as shown in
When the electrons 320 generated by the gas discharging mechanism and the additional secondary electrons 324 generated by the positive ions 322 hitting the secondary electron generation layer 308 hit the fluorescent layer 306, the generated light 330 is reflected by the reflective layer 314 to pass through the cathode structure 302b. The light source apparatus is also referred to as a reflective light source apparatus. Moreover, in the reflective light source apparatus, the anode structure 304b is formed by evaporating a transparent conductive material on the glass, and the reflective layer 314 may be a high-reflective metal or high-reflective optical film with a high-reflective metal evaporated thereon, for improving the reflectivity and increasing the brightness and luminous efficiency.
The material of the cathode structure 402a is a glass substrate with a metal layer or a transparent conductive material evaporated thereon. The anode structure 404a is located opposite to the cathode structure 402a. The anode structure 404a is a light transmissive structure, and the material thereof is. for example, an indium-tin-oxide (ITO), a fluorine-doped tin oxide (FTO), or another transparent conductive oxide (TCO) material. The cathode structure 402a and the anode structure 404a basically include, for example, a substrate and an electrode layer on the substrate. The actual structure of the cathode structure 402a and the anode structure 404a may vary depending on actual design, which is apparent to those of ordinary skill in the art, and will not be described herein.
The fluorescent layer 406 is disposed between the cathode structure 402a and the anode structure 404a, and is generally disposed on, for example, the anode structure 404a.
The discharge layer 408 is disposed on the cathode structure 402a. The material of the discharge layer 408 may be a material capable of easily discharging, such as a metal, carbon nanotube, carbon nanowall, carbon nanomaterial, column ZnO, or ZnO film.
The low-pressure gas layer 410 is disposed between the cathode structure 402a and the anode structure 404a, in which a low-pressure gas in a range of 10 to 10−3 torr for enabling the electron mean free path to be approximately the distance between cathode and anode.
In an embodiment, the light source apparatus further includes a sidewall structure 412 for separating the cathode structure 402a and the anode structure 404a by a distance, and meanwhile enclosing to form a low-pressure gas layer 410 for the low-pressure gas to be filled therein.
In the present invention, a thin gas is used to easily induce enough electrons 420 uniformly. A high voltage is used to allow the ionized electrons 420 to hit the fluorescent layer 406, so as to generate desired lights. In this embodiment, since the discharge layer 408 is a material capable of easily discharging, the operating voltage may be reduced.
In this embodiment, the anode structure 404a is a light transmissive structure, and the material thereof is, for example, an indium-tin-oxide, a fluorin-doped tin oxide, or another transparent conductive oxide (TCO) material. Therefore, when the electrons 420 hit the fluorescent layer 406, the generated lights 430 pass through the anode structure 404a. The light source apparatus is also referred to as a transmissive light source apparatus. Moreover, in the transmissive light source apparatus, the cathode structure 402a may be a high-reflective metal capable of improving the reflectivity and increasing the brightness and luminous efficiency.
It should be noted that since the filled gas is used to induce the cathode to uniformly emit electrons, the selected gas is not particularly restricted, and may be any gas or gas mixture, such as atmospheric air, He, Ne, Ar, Kr, Xe, H2, or CO2. Since the filled gas has a low or medium vacuum degree, the electron mean free path is large enough to allow the electrons to directly hit the material of the fluorescent layer 406 in the electric field, so as to emit desired lights.
The embodiment in
The embodiment in
The embodiment in
The light source apparatus as shown in
When the electrons 420 hit the fluorescent layer 406, the generated light 430 is reflected by the reflective layer 414 to pass through the cathode structure 402b. The light source apparatus is also referred to as a reflective light source apparatus. In the reflective light source apparatus, the anode structure 404b is preferably a high-reflective metal capable of improving the reflectivity and increasing the brightness and luminous efficiency.
The embodiment in
The embodiment in
In the above embodiment, if a light reflective mechanism is used, the light-emitting surface has a single side. Otherwise, if the light reflective mechanism is not used, the cathode structure and the anode structure are both made of transparent conductive materials to achieve the light transmission properties, such that the dual side light emitting effect can be achieved. Although the light intensity is weak, the light-emitting surface is the dual-side light-emitting surface. The dual-side light-emitting surface may also be modified into a single-side light-emitting surface by adding a reflective layer at the outside of any light-emitting surface. For example, one side of the transparent substrate is a transparent electrode structure, and the other side is formed with a reflective layer, such as a metal evaporated reflective layer.
Furthermore, the above light source apparatus may be fabricated into a backlight module for a display.
Moreover, a brightness enhance film (BEF) or a dual BEF (DBEF) may be added so as to increase the directionality and brightness according to the requirements of the backlight module.
The light emitting module in the above embodiment is formed by a single light emitting panel. However, the light emitting module may also be an array structure including a plurality of light emitting panel units.
Moreover, in order to increase the light intensity, for example, a plurality of light emitting panel units may be stacked. In
In view of the above, the light source apparatus provided by the first embodiment of the present invention has a secondary electron generation layer. Since the ionized positive ions in the gas may hit the secondary electron generation layer, additional secondary electrons may be generated when the positive ions hit the secondary electron generation layer on the cathode structure, thereby improving the luminous efficiency.
In the light source apparatus provided by the second embodiment of the present invention, a discharge layer may be disposed on both the cathode structure and the anode structure to reduce the operating voltage.
In the third embodiment of the present invention, the backlight module using the above embodiment may have an improved backlight module performance.
The light source apparatus of the present invention is applicable to the backlight module of a liquid crystal display (LCD). The light source apparatus may increase the light intensity and light uniformity, and further save the cost of the light guide panel and the diffuser required by the cold cathode fluorescence lamp (CCFL). The light source apparatus of the present invention incorporates the advantages of the plasma and field emission light sources. The light source apparatus of the present invention uses the thin gas to uniformly induce electrons from the cathode, thereby avoiding the defect of the difficulty in fabricating the cathode of the field emission light source.
The light source apparatus in the present invention is adapted to personal computers, household TV sets, automobile TV sets, or other devices having the backlight modules of the thin LCD having the relative functions. The field emission light emitting device in this form has the advantages of power saving, short response time, high luminous efficiency, easy to fabricate, environmental-friendly (mercury free), etc.
Different from the conventional field emission light source apparatus, the cathode structure of the light source apparatus of the present invention is merely a planar metal or a conductive film structure without being specially treated or provided with any material, so the structure is simpler. Moreover, the high vacuum packaging is not required in the present invention, and thus the manufacturing process is simplified and the mass production can be easily achieved. The cathode metal structure/high reflective material in the transmissive structure and the anode metal structure/high reflective material in the reflective structure can enhance the reflectivity and increase the brightness and luminous efficiency.
The wavelengths of the emitted lights in the present invention depend upon the types of the phosphors, so the light sources or backlight modules having different wavelengths may be designed depending on the different purposes of illumination or displays. The present invention may be designed to be planar or curved-surface backlight module. In the present invention, the reflective layer of the reflective type can avoid the light guide phenomenon, thereby increasing the brightness and luminous efficiency. The grounding circuit design may be optionally used to eliminate the charge accumulation in the phosphors.
Though the present invention has been disclosed above by the preferred embodiments, they are not intended to limit the present invention. Anybody skilled in the art can make some modifications and variations without departing from the spirit and scope of the present invention. Therefore, the protecting range of the present invention falls in the appended claims and their equivalents.
Number | Date | Country | Kind |
---|---|---|---|
96107136 A | Mar 2007 | TW | national |
96128647 A | Aug 2007 | TW | national |
96147952 A | Dec 2007 | TW | national |
This application is a continuation-in-part of a prior application Ser. No. 11/747,234, filed May 11, 2007. The prior application Ser. No. 11/747,234 claims the priority benefit of Taiwan application serial no. 96107136, filed on Mar. 2, 2007. This application also claims the priority benefits of Taiwan applications of Ser. No. 96128647, filed Aug. 3, 2007, and Ser. 96147952, filed Dec. 14, 2007. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.
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Number | Date | Country | |
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Child | 12039751 | US |