Abstract:
A flat luminescence lamp includes a first substrate having a first surface and a second surface, a second substrate having a first surface disposed facing opposite to the first surface of the first substrate, a first luminescence layer formed on the first surface of the first substrate, a second luminescence layer formed on the first surface of the second substrate, and a plurality of grooves formed on the second surface of the first substrate.

Description:
This is a divisional of copending application No. 09/893,554, filed on Jun. 29, 2001. 
     The present application claims the benefit of Korean Patent Application No. P2000-80211 filed on Dec. 22, 2000 in Korea, which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a luminescence lamp, and more particularly, to a flat luminescence lamp and a method for fabricating the same. 
     2. Background of the Related Art 
     Extra slim flat panel display devices that have a thickness less than a few centimeters have diverse areas of application, such as liquid crystal displays (LCDs) for notebook computers, monitors, spacecraft, and airplanes. Of the many different types of LCDs, the passive luminescence type LCD includes a backlight to be used as a light source disposed at the rear of a LCD panel. However, the use of such backlights in LCDs is inefficient in view of their weight, power consumption, and thickness. 
     Backlights that are commonly used in LCD devices are generally cylindrical fluorescent lamps disposed beneath a LCD panel. However, the fluorescent lamp must be spaced from the LCD panel in order to prevent the fluorescent lamp from being seen on the LCD panel. Accordingly, a light scattering mechanism is required to provide a uniform distribution of light across an entire surface of the LCD panel. Moreover, the specific type of fluorescent lamp disposed beneath the LCD panel limits the fabrication process of making a thin LCD panel. When a large-sized fluorescent lamp size is disposed beneath the LCD, a larger area of the light emitting surface is required. 
     In a LCD device using a fluorescent lamp fitted with a light plate, the fluorescent lamp is disposed to an outer circumference of the LCD panel for scattering light to an entire surface of the LCD panel. By using the light plate, a total luminance of the fluorescent lamp is low since the light must transmit through the light plate. Moreover, to ensure uniform distribution of the light upon the LCD panel, a high degree of optical design and fabrication technologies are required. Currently, a fluorescent lamp disposed beneath the LCD is suggested in which a number of individual lamps, or a single lamp that has multiple bends, are disposed beneath a display surface of the LCD panel. 
     A typical flat luminescence lamp will be explained with reference to  FIGS. 1 and 2 .  FIG. 1  shows a plan view of a flat luminescence lamp according to the related art, and  FIG. 2  shows a cross-sectional view across line I—I′ of FIG.  1 . 
     In  FIG. 1 , a luminescence lamp of the related art is provided with a lower plate  11  and an upper plate  11   a , a cathode electrode  13  disposed upon the lower plate  11 , an anode electrode  13   a  disposed upon the upper plate  11   a , a rectangular frame that includes four frame portions  19   a ,  19   b ,  19   c , and  19   d  sealing the upper plate  11   a  and the lower plate  11  by solder means, such as glass solder, and a plurality of supporting bars  21  disposed between the lower plate  11  and the upper plate  11   a.    
     The anode electrode  13   a  includes multiple portions that are arranged at fixed intervals in pairs of two, and the cathode electrode  13  includes single portions that are arranged at fixed intervals upon the lower plate  11  facing opposite to a space of the upper plate between the anode electrode  13   a . The cathode electrode  13  and the anode electrode  13   a  are covered with dielectric material, and each has lead lines electrically connected thereto for applying external voltages. The upper plate  11   a  and the lower plate  11  each have surfaces covered with fluorescent material and are disposed to opposite to each other with a discharge space formed therebetween. The discharge space includes xenon Xe gas that forms a plasma to emit UV rays when the external voltages are applied to the cathode electrode  13  and the anode electrode  13   a . The UV rays collide with the fluorescent material disposed upon both the upper plate  11   a  and the lower plate  11 , and excite the fluorescent material to generate visible light. Additionally, a reflective plate  14  is disposed above the cathode electrode  13  to prevent any light generated within the discharge space from leaking toward a back surface of the lower plate  11 . Accordingly, the supporting bars  21  are formed of glass for transmitting the light. 
     In  FIG. 2 , the lower plate  11 , which is made of glass, includes the cathode electrode  13  and a dielectric material layer  12  formed to cover the cathode electrode  13 . The reflective plate  14  is disposed upon the first dielectric material layer  12 , and a first fluorescent layer  15  is disposed upon the reflective plate  14 . The anode electrode  13   a  is disposed upon the upper plate  11   a , which is also made of glass, for inducing a discharge in association with the cathode electrode  13 . A second dielectric material layer  12   a  is disposed upon the upper plate  11   a  to cover the anode electrodes  13   a , and a second fluorescent material layer  15   a  is disposed upon the second dielectric material layer  12   a . The frame portions  19   a ,  19   b ,  19   c , and  19   d  are all formed between the upper plate  11   a  and the lower plate  11  for sealing the upper plate  11   a  and the lower plate  11  by glass solder. A flat heat dissipation plate  23  is disposed upon a back surface of the lower plate  11  for dissipating heat that is generated during discharge to an exterior of the lamp. The cathode electrode  13  and the anode electrode  13   a  are formed by either a silk print process or a vapor deposition process. Upon the application of the external voltage to the cathode electrode  13  and the anode electrode  13   a  via the lead lines, the xenon Xe gas within the discharge space disposed between the cathode electrodes  13  and the anode electrodes  13   a  forms a plasma. Accordingly, the plasma emits UV rays that collide with the first fluorescent material layer  15  and the second fluorescent material layers  15   a  to generate visible light, thereby illuminating the flat luminescence lamp. 
     However, implementing the flat luminescence lamp as described in a lightweight display, such as a notebook PC, increases thickness and weight since it uses two glass plates for the upper lower plates as well as a heat dissipation plate on the back surface of the lower plate. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a flat luminescence lamp and a method for fabricating a flat luminescence lamp that substantially obviate one or more of the problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a flat luminescence lamp that does not require a separate heat dissipation plate. 
     Another object of the present invention is to provide a flat luminescence lamp and a method for fabricating a flat luminescence lamp that can improve heat dissipation efficiency. 
     Another object of the present invention is to provide a flat luminescence lamp with reduced weight and thickness. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a flat luminescence lamp includes a first substrate having a first surface and a second surface, a second substrate having a first surface disposed facing opposite to the first surface of the first substrate, a first luminescence layer formed on the first surface of the first substrate, a second luminescence layer formed on the first surface of the second substrate, and a plurality of grooves formed on the second surface of the first substrate. 
     In another aspect, a flat luminescence lamp includes a first substrate having a first surface and a second surface, a plurality of grooves formed on the second surface of the first substrate, a second substrate having a first surface and a second surface, the first surface of the first substrate opposing the first surface of the second substrate, a plurality of first electrodes formed on the first surface of the first substrate, a plurality of second electrodes formed on the first surface of the second substrate opposing the first electrodes, a first fluorescent material layer formed on the first surface of the first substrate, a second fluorescent material layer formed on the first surface of the second substrate opposing the first fluorescent material layer, and a plurality of frame portions formed on the first surface of the first substrate and the first surface of the second substrate to seal the first substrate and the second substrate. 
     In another aspect, a method for fabricating a flat luminescence lamp includes the steps of forming a first substrate having a plurality of grooves on a first surface, forming a plurality of first electrodes on the first substrate, forming a plurality of second electrodes on a second substrate disposed opposite to the first substrate, forming a first fluorescent material layer on a second surface of the first substrate, forming a second fluorescent material layer formed on a surface of the second substrate, and forming a discharge space between the first substrate and the second substrate with a frame disposed between the first substrate and the second substrate. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: In the drawings: 
         FIG. 1  is a plan view showing of a flat luminescence lamp according to the related art; 
         FIG. 2  is a cross-sectional view across line I—I′ of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view showing an exemplary flat luminescence lamp in accordance with the present invention; 
         FIG. 4  is a plan view of a first substrate of a flat luminescence lamp in accordance with the present invention; 
         FIG. 5  is a cross-sectional view across line I—I′ in  FIG. 4 ; and, 
         FIGS. 6A  to  6 F are cross-sectional views showing the method steps for fabricating a flat luminescence lamp in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
       FIG. 3  shows a cross-sectional view of a flat luminescence lamp in accordance with an embodiment of the present invention. In  FIG. 3 , the flat luminescence lamp includes a first substrate  31 , a second substrate  33 , an insulating layer  35  formed upon the first substrate  31 , first electrodes  37  formed upon the insulating layer  35  at fixed intervals, a dielectric layer  39  formed upon the insulating layer  35  to cover the first electrodes  37 , a first fluorescent material layer  43  formed upon the first dielectric layer  39 , second electrodes  37   a  formed upon the second substrate  33 , a second dielectric layer  39   a  formed upon the second substrate  33  to cover the second electrodes  37   a , a second fluorescent material layer  43   a  formed upon the second dielectric layer  39   a , and a rectangular frame  45  for sealing the first substrate  31  and the second substrate  33 . Additionally, a reflective material layer  41  may be formed upon the first dielectric layer  39  for preventing light generated during discharge from leaking toward the first substrate  31 . Moreover, the first substrate  31  may be formed of a metal or ceramic, for example, and the second substrate may be formed of glass, for example. The frame may be formed of a paste including a glass material. The first substrate  31  may have a plurality of grooves formed at a back surface thereof for increasing the surface area to increase heat dissipation. The second electrode  37   a  may be formed of a metal or a transparent conductive material, such as ITO (Indium Tin Oxide), for example. Accordingly, since the second electrode transmits the light that is produced as a result of the UV rays colliding with the fluorescent material layer during discharge, a uniform luminescent surface can be obtained over an entire surface of the lamp. Further, a thickness of the insulating layer  35  is provided to electrically insulate the first substrate  31 . 
     In  FIG. 4 , the first substrate  31  of the flat luminescence lamp according to the present invention includes a flat layer  31   a , and a pattern layer  31   b  formed as a matrix or grating upon the flat layer  3   la . Since the pattern layer  31   b  is formed as a matrix, the heat generated during discharge may be efficiently dissipated. The pattern layer  31   b  may be formed photolithographically, for example, and may formed in any configuration that efficiently dissipates heat generated during discharge. 
     A method for fabricating a flat luminescence lamp in accordance with the present invention will be explained with reference to  FIGS. 6A  to  6 F. 
     In  FIG. 6A , a photosensitive material  100 , such as photoresist, may be coated onto a back surface of a first metal substrate  31 , and subsequently patterned by exposure and development to form a mask pattern  100   a  of a matrix form, as shown in FIG.  6 B. 
     In  FIG. 6C , the first metal substrate  31  is etched to a depth by using the mask pattern  100   a  as an etch mask to complete a first substrate  31  with a plurality of grooves formed in a back surface thereof. 
     In  FIG. 6D , the mask pattern  100   a  is removed and an insulating layer  35  is formed upon the first metal substrate  31 . Next, first electrodes  37  are formed upon the insulating layer  35  at fixed intervals, and second electrodes  37   a  are formed upon the second substrate  33 . The first electrodes  37  are cathode electrodes, and the second electrodes  37   a  are anode electrodes. The insulating layer  35  is formed to a predetermined thickness to electrically insulate the first substrate from the plurality of first electrodes. 
     In  FIG. 6E , a first dielectric layer  39  is formed upon the insulating layer  35  to cover the first electrode  37 , and a second dielectric layer  39   a  is formed upon the second substrate to cover the second electrodes  37   a . Subsequently, a first fluorescent material layer  43  is formed upon the first dielectric layer  39 , and a second fluorescent material layer  43   a  is formed upon the second dielectric layer  39   a . Additionally, a reflective material layer  41  may be formed before formation of the first fluorescent material layer  43  upon the first dielectric layer  39  to prevent light generated during discharge from leaking toward the first substrate  31 . 
     In  FIG. 6F , the first substrate  31  and the second substrate  33  are bonded together such that the first fluorescent material layer  43  faces the second fluorescent layer  43   a , thereby forming a discharge space and a fluorescent gas is subsequently injected through a gas injection opening (not shown). Finally, the first substrate  31  and the second substrate  33  are sealed with solder means, such as glass solder, within a rectangular frame  45  to complete a fabrication process of a flat luminescence lamp of the present invention. 
     Upon application of an external voltage to the cathode electrode  37 , and the anode electrode  37   a , via lead lines, the fluorescent gas, such as xenon Xe, forms a plasma within the discharge space to emit UV rays that collide with the first fluorescent material layer  43  and the second fluorescent material layer  43   a , thereby stimulating the emission of visible light. 
     The flat luminescence lamp of the present invention is not exclusively applicable as a light source for different types of displays, including of LCD device, at a back or front surface thereof, but also deployable as a lighting device itself. 
     As has been explained, the flat luminescence lamp and the method for fabricating the same have significant advantages over the related art. For instance, use of the flat luminescence lamp according to the present invention means no separate heat dissipation plate is required because metal or ceramic materials, for example, are selected as a first substrate material. As a result, the flat luminescence lamp of the present invention reduces overall weight, thickness, and cost of the LCD device. Furthermore, the plurality of grooves formed in the back surface of the first substrate permits efficient dissipation of heat generated during discharge. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the flat luminescence lamp and the method for fabricating a flat luminescence lamp of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.