Source: https://patents.justia.com/patent/7141931
Timestamp: 2019-11-19 21:20:17
Document Index: 258960433

Matched Legal Cases: ['art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art 31']

US Patent for Flat fluorescent lamp and backlight unit using the same Patent (Patent # 7,141,931 issued November 28, 2006) - Justia Patents Search
Justia Patents Having Electrode Exterior To EnvelopeUS Patent for Flat fluorescent lamp and backlight unit using the same Patent (Patent # 7,141,931)
However, since the conventional flat fluorescent lamp mainly employs an inert gas, such as xenon (Xe), neon (Ne) or Xe—Ne, as a discharge gas, it has an alternating voltage as high as 2 kV that is applied to the discharge electrodes 14, and a light efficiency as low as 30 lm/W or less. Hence, with the intention of obtaining large quantities of light, the discharge channel of the above lamp 10 should be enlarged and an operation power should increase, resulting in increased power consumption. In addition, since the used discharge gas is inert, the fluorescent material layer 16 is excited by ultraviolet rays of 147 or 173 μm. Consequently, the above fluorescent lamp is disadvantageous in terms of using an expensive fluorescent material, instead of a mass-produced fluorescent material for ultraviolet rays of 254 μm.
FIGS. 4a to 4c are cross-sectional views of modifications of partitions included in the flat fluorescent lamp of FIG. 2;
FIGS. 5a to 5e are top views of modifications of electrodes included in the flat fluorescent lamp of FIG. 2;
FIG. 2 is an exploded perspective view of a flat fluorescent lamp, according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along the line A—A of FIG. 2.
In addition, modifications of the partitions 24 are shown in FIGS. 4a to 4c, in which the partitions 24 vary in shapes thereof, depending on the back substrate 21 and the front substrate 22. For instance, the partitions 24 may be integratedly formed with the back substrate 21 as in FIG. 4a, or with the front substrate 22 as in FIG. 4b, by subjecting the back substrate 21 or the front substrate 22 to sand blasting or laser etching or softening and then molding under pressure or reduced pressure.
Further, as seen in FIG. 4c, the partitions 24 include first partitions 24a integratedly formed with the back substrate 21 and second partitions 24b integratedly formed with the front substrate 22. As such, it is preferred that the first partitions 24a and the second partitions 24b are manufactured to be alternately disposed.
According to FIG. 2, the fluorescent material layer 25 is coated along the surface of the discharge channel defined by the back substrate 21, the front substrate 22, and the partitions 24. Also, the fluorescent material layer 25, as seen in FIGS. 4a to 4c, is formed so that a thickness (T2) of the fluorescent material layer coated to the front substrate 22 is less than a thickness (T1) of the fluorescent material layer coated on the back substrate 21 and the partitions 24, in consideration of transmission of the excited light through the fluorescent material layer 25 coated to the front substrate 22. Preferably, the fluorescent material layer 25, which is coated on the back substrate 21, the front substrate 22 and the partitions 24, is thinly coated at 25 μm or less.
Into the discharge channel defined by the partitions 24, a discharge gas, including a rare gas, such as mercury (Hg), argon (Ar), neon (Ne), helium (He), krypton (Kr) or xenon (Xe) used alone, or a mixture gas, such as Ne—Ar, He—Ar and Ne—Xe, is introduced. As a main exciting source of a fluorescent material constituting the fluorescent material layer 25, use is taken of ultraviolet rays of mercury or xenon.
As shown in FIGS. 2 and 5a, a plurality of floating electrodes 26a may be disposed between the electrodes 26 and 26′. In this case, additional floating electrodes 26a are intermittently placed in the discharge channel, and thus a voltage is induced by a power applied to the electrodes 26 and 26′, thus causing the discharge. Accordingly, a more stable discharge can be achieved by initiating the discharge at a relatively low voltage while the electrodes 26 and 26′ remain in the positions.
As shown in FIGS. 5b to 5e, the mutually opposite two electrodes 26 and 26′ may be formed to have stripe, square- and circle-shaped apertures 26b, 26c and 26d. The apertures 26b, 26c and 26d of the electrodes 26 and 26′ disposed to both ends of the back substrate 21 increase in sizes toward the inner sides of the electrodes 26 and 26′ facing each other. That is, the sizes of the apertures 26b, 26c and 26d of the electrodes 26 and 26′ gradually decrease toward the outer sides of the electrodes 26 and 26′ facing each other. Thus, areas per unit surface areas of the mutually opposite electrodes 26 and 26′ of the back substrate 21 gradually decrease toward the outer sides. However, the shapes of the apertures 26b, 26c and 27d of the electrodes 26 and 26′ are not limited to the above examples.
As seen in FIG. 6, the light diffusion part 31 has a first function which diffuses the light generated by a fluorescent material excited from the flat fluorescent lamp 20, and a second function allowing a non-transmitting region by the partitions 24 not to display. The light diffusion part 31 has a transparent plate 31a that transmits the light from the flat fluorescent lamp 20, and a diffusion plate 31b disposed to be in contact with the transparent plate 31a to diffuse the light The diffusion plate 31b is preferably made of an acryl plate having diffusibility.
The light diffusion part 31 is disposed so that a distance (L) between an upper surface of the flat fluorescent lamp 20 and an upper surface of the diffusion plate 31b is as long as ½ to 2 times of pitch (P) of the partitions 24 or pitch of the channel defined by the partitions 24.
The insulating layer 32 is attached to a lower surface of the reflective layer 28 of the flat fluorescent lamp 20 through a first adhesive layer 32a, to insulate a lower portion of the flat fluorescent lamp 20. The first adhesive layer 32a is made of a material which has heat resistance and can be firmly fixed to the flat fluorescent lamp 20 even in the state of the lamp 20 being heated by the discharge.
The base member 33 is attached to a lower surface of the insulating layer 32 through a second adhesive layer 32b, to prevent any bending of the flat fluorescent lamp 20 or destruction thereof by external impact The base member 33 is preferably made of a metal sheet, and includes protrusions of lattice structures or is cast, so as not to be bent.
As in FIG. 8, the light diffusion part 31 functions, firstly, to diffuse the light generated by the fluorescent material which is excited from the flat fluorescent lamp 20, and, secondly, to allow a non-transmitting region by the partitions 24 not to display. The light diffusion part 31 has a transparent plate 31a that transmits the light from the flat fluorescent lamp 20, and a diffusion plate 31b disposed to be in contact with the transparent plate 31a to diffuse the light. In such a case, the diffusion plate 31b is preferably made of an acryl plate having diffusibility.
The insulating reflective layer 32 is provided under the fluorescent material layer 25 of the flat fluorescent lamp 20 through a first adhesive layer 32a, to insulate a lower portion of the flat fluorescent lamp 20 and simultaneously reflect the light. The adhesive layer 32a is made of a material which has heat resistance and can be firmly fixed to the flat fluorescent lamp 20 even in the state of the lamp 20 being heated by the discharge.
The base member 33 is disposed under the insulating reflective layer 32 through a second adhesive layer 32b, to prevent bending of the flat fluorescent lamp 20 or destruction thereof by external impact. The base member 33 is preferably made of a metal sheet, and includes protrusions of lattice structures or is cast, so as not to be bent.
During the operation of the unit, the mercury-impregnated metal pieces 29, which are placed in the discharge channel defined by the partitions 24, act to feed mercury to constantly maintain a mercury partial pressure in the discharge channel. In particular, the electrode 26 has a relatively greater width and includes the apertures 26b, 26c and 26d, and thus the plasma discharge region can be formed to be relatively wider. Since the apertures 26b, 26c and 26d of the electrode 26 are formed to have sizes increasing gradually toward the inner sides of the electrodes, a non-uniform plasma discharge by the voltage difference due to a nearing of the electrode 26 can be fundamentally solved.
In an electrode structure having the floating electrode 26a, the discharge can occur even at a low voltage by narrowing a distance between the electrodes by a floating voltage.
Further, in a combination electrode structure having the apertures 26b, 26c and 26d and the floating electrode 26a, an electrode design can be easily realized. Also, a distortion phenomenon of the discharge by a surface electrical field of the electrode per se is drastically decreased, and thus non-uniform luminance can be prevented upon tuning on the lamp. According to experiments of the present inventors, since the distance between the electrodes can decrease, a voltage required to initiate the discharge reduces by 30% or more, and the shape of the electrode pattern and the apertures are modified, thus controlling a light-emitting distribution.
The light emitted by the flat fluorescent lamp 20 is irradiated through the transparent plate 31a and the diffusion plate 31b of the light diffusion part 31 supported to the base member 33. As such, the distance from the fluorescent lamp 20 to the diffusion plate 31b is as long as ½ to 2 times of the pitch of each of the partitions. Hence, spot patterns caused by the luminance of the channel relatively higher than that of the partitions can be eliminated.
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Patent Publication Number: 20050116607
Inventors: Deuk-il Park (Suwon-si, Gyeonggi-do), Choong-Yop Rhew (Suwon-si, Gyeonggi-do), Ok-Bin Sur (Osan-si, Gyeonggi-do)
Application Number: 10/767,066
Current U.S. Class: Having Electrode Exterior To Envelope (313/607); Electrode Exterior To Envelope (313/234); With Gaseous Discharge Medium (313/484); Phosphor On Envelope Wall (313/485); Start Electrode Exterior To Envelope (313/594)