This application claims the benefit of Taiwan application Serial No. 100141123, filed Nov. 10, 2011, the disclosure of which is incorporated by reference herein in its entirety.
The technical field relates in general to a discharge lamp, and more particularly to a gas discharge lamp and a manufacturing method thereof.
During the conventional process for manufacturing gas discharge lamp, the metal electrode and the quartz glass are connected together. However, since coefficient of thermal expansion of the quartz glass is very small, that is, about 5×10−7/° C. but the coefficient of thermal expansion of metal normally ranges between (45˜90)×10−7/° C., the quartz glass may easily crack and result in poor performance in air-proof if the quartz glass and the metal electrode are directly connected together. The crack of the quartz glass is mainly due to the big difference in the coefficients of thermal expansion between the metal electrode and the quartz glass. To resolve the above crack problem which occurs when bonding the metal electrode and quartz glass together, many bonding methods and bonding structures are provided. However, the associated manufacturing process is complicated and the yield rate of the manufacturing process is still not satisfactory.
The disclosure is directed to a gas discharge lamp and a manufacturing method thereof which achieve better air-proof effect with enhanced bonding strength.
According to one embodiment, a gas discharge lamp including a crystal tube, a connecting portion and a metal electrode rod is provided. The crystal tube includes at least one terminal portion and an axial segment. The terminal portion is located at an end of the axial segment. The connecting portion is constituted by N glass ring bands, wherein N is an integral equal to or greater than 4. The glass ring bands are connected to the terminal portion of the crystal tube along an axial line of the axial segment in sequence. The first glass ring band connected to the terminal portion has a first coefficient of thermal expansion. The metal electrode rod is embedded in the terminal portion, and an end of the metal electrode rod away from the terminal portion is connected to the Nth glass ring band. The Nth glass ring band has a second coefficient of thermal expansion greater than the first coefficient of thermal expansion.
According to another embodiment, a manufacturing method of a gas discharge lamp is provided. The method includes the following steps. Firstly, N glass ring bands are formed along an axial line of a crystal tube in sequence, wherein N is an integral equal to or greater than 4, and the first glass ring band connected to the terminal portion of the crystal tube has a first coefficient of thermal expansion. Then, a metal electrode rod is inserted into the crystal tube and the air inside the crystal tube is extracted, such that the Nth glass ring band and the metal electrode rod are thermo-bonded in vacuum, wherein the Nth glass ring band has a second coefficient of thermal expansion greater than the first coefficient of thermal expansion.
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
According to a gas discharge lamp and a manufacturing method thereof disclosed in the present embodiment of the disclosure, N glass ring bands arranged along the axial line are sequentially connected between the crystal tube and the metal electrode rod, such that the metal electrode rod may be bonded and sealed in the crystal tube, wherein N is an integral equal to or greater than 4 for example. In an embodiment, the glass ring bands are ranked according to the magnitudes of the coefficients of thermal expansion. Therefore, the terminal portion of the crystal tube is connected to the glass ring band with smaller coefficient of thermal expansion, and the metal electrode rod is connected to the glass ring band with larger coefficient of thermal expansion, and better air-proof effect with enhanced bonding strength can thus be achieved.
A number of embodiments are disclosed below for elaborating the invention. However, the embodiments of the invention are for detailed descriptions only, not for limiting the scope of protection of the invention.
Referring to
In an embodiment, the first coefficient of thermal expansion such as ranges between 5×10−7/° C.˜15×10−7/° C. With respect to the coefficient of thermal expansion (5×10−7/° C.˜6×10−7/° C.) of the crystal tube 10, the coefficient of thermal expansion of the first glass ring band 20-1 is very close to the coefficient of thermal expansion of the crystal tube 10, hence avoiding the crystal tube 10 cracking due to repeated thermal stress.
Referring to Table 1, a comparison of coefficient of thermal expansion and softening temperature for four sequentially bonded glass ring bands is shown. The coefficient of thermal expansion of the first glass ring band 20-1 (No. 1) connected to the terminal portion 12 of the crystal tube 10 is about 10×10−7/° C. Those glass ring bands (No. 2˜4) farther away from the terminal portion 12 have larger coefficients of thermal expansion, which are respectively equal to 20×10−7/° C., 30×10−7/° C. and 39×10−7/° C. In addition, the difference in the coefficients of thermal expansion between two neighboring glass ring bands is about 10×10−7/° C.
As indicated in
In the present embodiment, the Nth glass ring band 20-N bonded with the metal electrode rod 30 has a second coefficient of thermal expansion. The second coefficient of thermal expansion ranges such as between 35×10−7/° C.˜45×10−7/° C. As shown in Table 1, the coefficient of thermal expansion of the Nth glass ring band 20-N (No. 4) is about 39×10−7/° C. With respect to the coefficient of thermal expansion of the metal electrode rod 30 which is 40×10−7/° C.˜45×10−7/° C., the coefficient of thermal expansion of the Nth glass ring band 20-N is very close to the coefficient of thermal expansion of the metal electrode rod 30, hence avoiding the crystal tube 10 cracking due to repeated thermal stress.
Referring to Table 2, a comparison of coefficient of thermal expansion and softening temperature for seven sequentially bonded glass ring bands is shown. The coefficient of thermal expansion of the first glass ring band 20-1 (No. 1) connected to the terminal portion 12 of the crystal tube 10 is about 10×10−7/° C. Those glass ring bands (No. 2˜7) farther away from the terminal portion 12 have larger coefficients of thermal expansion, which are respectively equal to 15×10−7/° C., 20×10−7/° C., 25×10−7/° C., 30×10−7/° C., 33×10−7/° C. and 39×10−7/° C. The difference between the coefficients of thermal expansion of two neighboring glass ring bands is about 3˜6×10−7/° C.
Referring to
As shown in Table 1, the softening temperature of the first glass ring band 20-1 (No. 1) connected to the terminal portion 12 of the crystal tube 10 is about 1210° C. Those glass ring bands (No. 2˜4) farther away from the terminal portion 12 have lower softening temperatures, which are respectively equal to 1190° C., 1075° C. and 775° C. Therefore, the junction temperature for the terminal portion 12 of the crystal tube 10 and the first glass ring band 20-1 is about 1200° C., and the junction temperature for the metal electrode rod 30 and the Nth glass ring band 20-N is about 775° C.
Then, as indicated in
Then, as indicated in
Referring to
According to the gas discharge lamp and the manufacturing method thereof disclosed in the above embodiments of the disclosure, N glass ring bands arranged along the axial line are connected in sequence between the crystal tube and the metal electrode rod, such that the metal electrode rod may be bonded and sealed in the crystal tube. Since the terminal portion of the crystal tube is connected to the glass ring band with smaller coefficient of thermal expansion, and the metal electrode rod is connected to the glass ring band with larger coefficient of thermal expansion, better air-proof with enhanced bonding strength can thus be achieved.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
Number | Date | Country | Kind |
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100141123 | Nov 2011 | TW | national |