BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial sectional view of a conventional planar light source;
FIGS. 2A to 2D are sectional views of the fabricating process of a planar light source according to the first embodiment of the invention;
FIG. 3 is an enlarged schematic view after a dielectric material layer is formed on the first substrate according to the first embodiment of the invention;
FIG. 4 is a curve graph depicting the time-temperature relation for forming the first striped dielectric pattern;
FIG. 5 is an enlarged schematic view of the first striped dielectric pattern in FIG. 2D; and
FIG. 6 is a sectional view of a planar light source according to the second embodiment of the invention.
DESCRIPTION OF EMBODIMENTS
First Embodiment
FIGS. 2A to 2D depict the flow chart of fabricating a planar light source according to the first embodiment of the invention. Referring to FIG. 2A, first, a first substrate 210a is provided, and multiple first electrodes 230 in parallel are formed on the first substrate 210a. It should be noted that in order to improve the light utilization of the planar light source, the present embodiment, for example, adopts forming a reflecting layer 290 on the first substrate 210a before forming the first electrodes 230, and then forming the first electrodes 230 on the reflecting layer 290. Of course, in other embodiments, the reflecting layer (not shown) can also be disposed on the lower surface of the first substrate 210a without first electrodes 230, which is not limited by the present invention.
Next, as shown in FIG. 2B, multiple sets of first dielectric patterns 240 are formed on the first substrate 210a, wherein each set of first dielectric patterns 240 at least includes two first striped dielectric patterns 240a, and each first striped dielectric pattern 240a covers a first electrode 230. Particularly, the edges 244 of the top of the first striped dielectric pattern 240a are raised in a peak shape. As such, when voltages are applied to the first electrodes 230, the edges 244 of the top of the first striped dielectric patterns 240a can accumulate more charge compared with other parts of the first striped dielectric patterns 240a, thus causing the point discharge.
The method for forming the first striped dielectric pattern 240a will be illustrated below with the embodiments, but the invention will not be limited to these embodiments. FIG. 3 is an enlarged schematic view of the embodiment after the dielectric material layer is formed on the first substrate. FIG. 4 is a curve graph depicting the time-temperature relation for forming the first striped dielectric pattern 240a.
Referring to FIGS. 3 and 4, according to the embodiment, the method for forming the first striped dielectric pattern 240a is first, forming a dielectric material layer 246 to cover the first electrode 230, wherein the dielectric material layer 246 usually contains solvent 246a, bonding agent 246b, and dielectric ceramic powder 246c; then, heating the dielectric material layer 246 to the temperature T1, and keeping heating under the temperature T1 for the duration t1, so as to evaporate the solvent 246a from the dielectric material layer 246. Herein, the temperature T1 is, for example, 150° C., and the duration t1 is, for example, 10 minutes.
Then, the dielectric material layer 246 is heated from the temperature T1 to the temperature T2, and is continuously heated under the temperature T2 for the duration t2, so as to evaporate the solvent 246b from the dielectric material layer 246. Herein, the temperature T2 is, for example, 400° C., and the duration t2 is, for example, 20 minutes. Afterward, the dielectric material layer 246 is heated from the temperature T2 to the temperature T3, and is continuously heated under the temperature T3 for the duration t3, so as to sinter the dielectric ceramic powder 246c from the dielectric material layer 246. Finally, the dielectric material layer 246 is cooled down to the normal temperature. Herein, the temperature T3 is, for example, 540° C., and the duration t3 is, for example, 20 minutes.
After the steps of heating, the formed first striped dielectric pattern 240a is shown in FIG. 2B, i.e., the edges 244 of the top are raised in a peak shape.
Of course, those skilled in the art should understand that the first striped dielectric pattern 240a in FIG. 2B can be fabricated by other methods, such as etching process or sandblasting process according to other embodiments of the invention.
Referring to FIG. 2C, after the first striped dielectric patterns 240a are formed, a spacer 222, for example, is first formed between each set of first dielectric patterns 240 for isolating multiple discharge spaces 280. Then, a phosphor layer 250 is formed between the first striped dielectric patterns 240a in the discharge spaces 280. It should be noted that the phosphor layer 250 can cover the first striped dielectric patterns 240a and the sidewall of the spacers 222 at the same time.
Next, referring to FIG. 2D, a second substrate 210b is provided, and the second substrate 210b is bound above the first substrate 210a by using a sealant 220. Meanwhile, a discharge gas 260 is injected between the first substrate 210a and the second substrate 210b, i.e., the fabricating process of the planar light source 200 is approximately finished. The discharge gas 260 can be, for example, xenon, neon, argon, helium, deuterium gas, or other discharge gas. Besides, a phosphor layer 252, for example, has already been formed on the second substrate 210b.
The planar light source fabricated according to the above embodiment will be illustrated below. Referring to FIG. 2D, the planar light source 200 includes a first substrate 210a, a second substrate 210b, a sealant 220, multiple first electrodes 230, multiple sets of first dielectric patterns 240, a phosphor layer 250, and a discharge gas 260. The second substrate 210b is disposed above the first substrate 210a. The sealant 220 is disposed between the first substrate 210a and the second substrate 210b to form a cavity 270 between the first substrate 210a, the second substrate 210b, and the sealant 220. The multiple first electrodes 230 and the multiple sets of the first dielectric patterns 240 are all disposed on the first substrate 210a. A reflecting layer 290 is further disposed on the first substrate 210a, and the first electrodes 230 and the first dielectric patterns 240 are disposed on the reflecting layer 290.
Particularly, each set of the first dielectric patterns 240 at least includes two first striped dielectric patterns 240a, and each of the first striped dielectric patterns 240a covers a first electrode 230. More particularly, the edges 244 of the top of each first striped dielectric pattern 240a are raised in a peak shape, so during the discharge process of the planar light source 200, the edges 244 of the top of the first striped dielectric pattern 240a can accumulate more charge compared with other parts, thereby causing the point discharge.
The first striped dielectric pattern will be illustrated below, but the invention will not be limited to this. FIG. 5 is an enlarged schematic view of the first striped dielectric pattern 240a in FIG. 2D. Referring to FIG. 5, the width of the first striped dielectric pattern 240a is L1, and the height is H1. The height of two edges 244 of the top of the first striped dielectric pattern 240a is H2, and the pitch between two peak shaped edges 244 of the same first striped dielectric pattern 240a is L2. In the embodiment, the width L1 of the first striped dielectric pattern 240a is about 1 to 5 cm, and the height H1 is about 50 to 400 μm. The pitch L2 between two peak shaped edges 244 of the top is about 1 to 4 cm, and the height falls in the range of 3 to 30 μm.
Referring to FIG. 2D again, the phosphor layer 250 is disposed between the first striped dielectric patterns 240a in each of the discharge spaces 280. Of course, another phosphor layer 252 can also be disposed on the second substrate 210b. The discharge gas 260 is injected into each of the discharge spaces 280 of the cavity 270, and can be, for example, xenon, neon, argon, helium, deuterium gas, or other discharge gas. Besides, the spacers 222 can be further disposed between the first substrate 210a and the second substrate 210b for keeping the pitch between the first substrate 210a and the second substrate 210b.
In view of the above, the edges 244 of the top of the first striped dielectric pattern 240a are raised in a peak shape, which results in point discharge and thereby increasing the plasma generated during the discharge process, so as to increase the ultraviolet light generated by activating the plasma and further improve the brightness of the visible light emitted by the phosphor layer 250. As such, the illumination brightness of the planar light source 200 can be effectively enhanced.
Second Embodiment
FIG. 6 is a sectional view of a planar light source according to the second embodiment of the invention. Referring to FIG. 6, the difference between the planar light source 300 and the planar light source 200 of the above embodiment is that the second electrodes 232 and second dielectric patterns 242 are formed on the second substrate 210b. The fabricating processes and structures of the first electrodes 230, the first dielectric patterns 240, the phosphor layer 250, the reflecting layer 290 etc. on the first substrate 210a of the planar light source 300 are identical or similar to that of the above-mentioned fabricating method, which will not be described herein.
In the embodiment, before the first substrate 210a and the second substrate 210b are bound, multiple second electrodes 232 are disposed on the second substrate 210b, wherein each of the second electrodes 232 is disposed in a discharge space 280 after the first substrate 210a and the second substrate 210b are bound. Next, multiple second striped dielectric patterns 242 are formed on the second substrate 210b, and each of the second striped dielectric patterns 242 covers a second electrode 232. Herein, the method for fabricating the second striped dielectric pattern 242 is identical or similar to that of the first striped dielectric pattern 240. As such, the edges 244 of the top of the second striped dielectric pattern 242 are raised in a peak shape. After that, the phosphor layer 252 disposed on the second substrate 210b is disposed on the sidewall of the second striped dielectric pattern 242.
In view of the above, as the edges of the top of the striped dielectric pattern in the planar light source are raised in a peak shape, a point discharge is induced, thereby enhancing the illumination brightness of the planar light source.
Though the present invention has been disclosed above by the preferred embodiments, it is not intended to limit the invention. Anybody skilled in the art can make some modifications and variations without departing from the spirit and scope of the invention. Therefore, the protecting range of the invention falls in the appended claims.
Patent Application
20080006830
