HK1055011B - Cold-cathode fluorescent tube with double layer tube structure - Google Patents

Description

Cold cathode fluorescent lamp tube with double-layer lamp tube structure

Technical Field

The present invention relates to a gas discharge lamp, and more particularly, to a cold cathode fluorescent lamp having a double-layered lamp structure.

Background

Cold cathode fluorescent lamp tubes are widely used in the fields of liquid crystal displays, scanners, automobile instrument panels, micro advertising lamp boxes, mirror frames and the like at present because of high luminous intensity, uniform luminous intensity, extremely fine lamp tubes and various shapes. In general, it is a novel miniature strong light source as a background light source of the above products.

The operating voltage of a ccfl depends mainly on the structure and material of the lamp (such as the diameter of the lamp, the length of the lamp, the pressure inside the lamp, the electrode material and its structure, the manufacturing process of the lamp, etc.) and the requirements of the lighting circuit. Therefore, after the lamp tube is manufactured, the output power of the lamp tube generally does not change greatly along with the increase of the working voltage. The increase in lamp output power (i.e., the increase in lamp brightness) depends primarily on the increase in current. The increase of the current of the lamp tube will cause the temperature of the two poles of the lamp tube to be increased, thereby causing the working temperature of the whole lamp tube to be increased. If the lamp tube is locally cooled by the environmental influence, the brightness of the corresponding part is also darkened, thereby causing the uneven brightness of the lamp tube. To solve this problem, a double-tube structure cold cathode fluorescent lamp (see fig. 1) has been developed in the market. The fluorescent lamp comprises an inner-layer fluorescent lamp tube 3, electrodes 1 arranged at two ends of the inner-layer fluorescent lamp tube 3, a fluorescent layer 5 coated on the surface of the inner wall of the inner-layer fluorescent lamp tube 3 and gas 6 filled in the inner-layer fluorescent lamp tube 3, and is characterized in that a transparent glass tube 2 is sleeved outside the inner-layer fluorescent lamp tube 3, a gap 4 between the two tubes is vacuumized or filled with gas with certain air pressure, and a tube end 7 of the outer-layer glass tube 2 is sealed with a tube end of the inner-layer fluorescent lamp tube 3.

When the fluorescent lamp shown in fig. 1 works, the inner layer fluorescent lamp 3 is less affected by the external temperature change and the environmental condition change due to the obstruction of the outer layer glass tube 2, and the whole lamp has uniform brightness and stable work. Even if the ambient temperature is relatively low, the inner fluorescent tube 3 can be ignited in a short time and reach a prescribed brightness.

However, in the fluorescent lamp tube shown in fig. 1, the tube end of the inner layer fluorescent lamp tube 3 is completely embedded in the tube end of the outer layer glass tube 2, i.e. the tube ends are integrally arranged. When the environmental temperature is lower, the temperature difference between the two tubes can reach more than 100 ℃, and the sealing part of the tube end is easy to crack due to the stress caused by the temperature difference between the two tubes of glass, thereby causing the rejection of the fluorescent tube. Therefore, the inherent defects of the fluorescent lamp tube greatly limit the application prospect of the fluorescent lamp tube in various environments.

Disclosure of Invention

The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a cold cathode fluorescent lamp which is suitable for various environmental conditions and can be safely and reliably used.

According to the present invention, there is provided a cold cathode fluorescent lamp comprising an inner layer fluorescent lamp tube and an outer layer glass tube fitted around the outside of the inner layer fluorescent lamp tube, the inner layer fluorescent lamp tube being disposed apart from the outer layer glass tube with a gap therebetween, the cold cathode fluorescent lamp tube further comprising electrodes sealed at the tube ends of the inner layer fluorescent lamp tube and the outer layer glass tube, wherein the inner surface of at least one tube end of the outer layer glass tube is not in contact with the outer surface of at least one tube end of the inner layer fluorescent lamp tube but is connected together by the electrodes provided at the tube ends of the outer layer glass tube and the inner layer fluorescent lamp tube.

According to the cold cathode fluorescent lamp tube, the electrode is provided with the elastic expansion eliminating part at the position between the tube end of the inner layer fluorescent lamp tube and the tube end of the outer layer glass tube.

The cold cathode fluorescent lamp tube according to the invention, wherein the elastic expansion part of the electrode is a bent section of the electrode.

The cold cathode fluorescent lamp tube comprises an outer layer glass tube end, an inner layer fluorescent lamp tube end and an elastic expansion part, wherein the elastic expansion part of the electrode comprises electrodes which are respectively packaged on the outer layer glass tube end and the inner layer fluorescent lamp tube end, and a transition part connected between the two electrodes.

The cold cathode fluorescent lamp tube according to the present invention, wherein the elastic swelling portion of the electrode includes notches alternately formed at diametrically opposite sides of the electrode.

The cold cathode fluorescent lamp tube adopts a double-layer lamp tube structure, so that the inner layer fluorescent lamp tube is less influenced by the temperature change of the external environment. Moreover, because the inner layer fluorescent lamp tube and the outer layer glass tube are separately arranged, the tube end of the inner layer fluorescent lamp tube and the tube end of the outer layer glass tube are not integrally packaged into a whole, and the burst breakage rate of the two tube ends caused by large temperature difference is greatly reduced. Furthermore, the electrode packaged between the end of the inner layer fluorescent tube and the end of the outer layer glass tube is provided with an elastic expansion eliminating part which can completely absorb the stress generated by the temperature difference between the inner layer tube and the outer layer tube, thereby eliminating the burst and damage phenomena of the cold cathode fluorescent tube.

Drawings

Fig. 1 is a schematic view showing a structure of a double-layered fluorescent lamp tube of the prior art.

Fig. 2 is a schematic view showing the structure of a cold cathode fluorescent lamp according to a first embodiment of the present invention.

Fig. 3 is a schematic view showing a structure of a cold cathode fluorescent lamp according to a second embodiment of the present invention.

Fig. 4 is a schematic view showing a structure of a cold cathode fluorescent lamp according to a third embodiment of the present invention.

Fig. 5 is a schematic view showing a structure of a cold cathode fluorescent lamp according to a fourth embodiment of the present invention.

Fig. 6 is a schematic view showing a structure of a cold cathode fluorescent lamp according to a fifth embodiment of the present invention.

Detailed Description

Fig. 2 is a schematic structural view of a cold cathode fluorescent lamp tube according to a first embodiment of the present invention. Unlike the fluorescent lamp shown in fig. 1, the end of the inner fluorescent lamp tube 3 is not integrally provided with the end of the outer glass tube 2, but the two tubes are substantially separately provided. The tube end of the inner fluorescent tube 3 is in contact with and sealed with only opposite surfaces of the tube end of the outer glass tube 2, that is, the inner surface of the tube end of the outer glass tube 2 is in contact with only the curved slope portion or the rounded portion of the outer surface of the tube end of the inner fluorescent tube 3. Compared with the fluorescent lamp tube shown in figure 1, the contact area between the tube end of the inner layer fluorescent lamp tube 3 and the tube end of the outer layer glass tube 2 is smaller and the contact is shallow, so that the stress generated by the temperature difference between the two tubes is greatly reduced, and the burst and the breakage of the lamp tube are obviously reduced.

In order to further reduce the influence of the temperature difference between the inner and outer tubes, the inner fluorescent tube 3 and the outer glass tube 2 can be made of glass tubes with different expansion coefficients. The inner fluorescent tube is operated at a high temperature of about 100 deg.C, so that a glass having a small expansion coefficient is used, for exampleCoefficient of expansion of 3.2X 10^-6High borosilicate glass at/° c. The outer glass tube has a relatively low temperature, approximately close to ambient temperature, so that a glass having a relatively high coefficient of expansion, e.g. 4.0X 10^-6Borosilicate glass at/° c. Therefore, when the fluorescent lamp tube works, the stress generated by the temperature difference between the inner layer and the outer layer can be reduced due to the difference of the expansion coefficients of the two tubes of glass, thereby further reducing the burst and damage of the fluorescent lamp tube. Of course, this solution of making the inner and outer tubes of glass with different expansion coefficients is also applicable to the lamp shown in fig. 1 and 3 to 6. When applied to the lamp shown in fig. 1, the burst breakage rate of the lamp can be reduced from the original about 60% to about 30%.

Fig. 3 is a schematic structural diagram of a cold cathode fluorescent lamp tube according to a second embodiment of the present invention. Referring to fig. 3, the tube end of the inner fluorescent tube 3 and the tube end of the outer glass tube 2 are not directly sealed together, but the relative position between the two tubes is maintained by the same electrode 1 disposed at the tube ends of the two tubes. Therefore, the pipe ends of the inner layer and the outer layer of the two pipes are not in direct contact with each other, namely the pipe end inner surface of the outer layer of the glass pipe is not in contact with the pipe end outer surface of the inner layer of the fluorescent lamp tube, and the inner layer and the outer layer of the two pipes are isolated by the vacuum layer, so that the temperature difference between the inner layer and the outer layer of the two pipes can not be directly reflected to the pipe ends of the two pipes when the fluorescent lamp tube works, and the burst breakage rate of the fluorescent lamp tube is greatly reduced.

Fig. 4 is a schematic structural diagram of a cold cathode fluorescent lamp tube according to a third embodiment of the invention. Referring to fig. 4, the pipe ends of the inner and outer layers of the two pipes are not directly sealed together, but are connected together by the electrodes 1 disposed at the pipe ends of the two pipes. Wherein, the tube end of the inner layer fluorescent tube 3 is encapsulated on the tungsten nickel electrode 11, for example, and the tube end of the outer layer glass tube 2 is encapsulated on the Dumet wire electrode 12, for example. The two electrodes 11 and 12 are joined together resiliently by welding, i.e. one of the electrodes forms a resilient, upset-like section 13 at the location where it is joined to the other electrode. Thus, when the fluorescent lamp tube works, the expansion deformation of the inner and outer layers of the fluorescent lamp tube caused by the temperature difference is completely absorbed by the elastic part 13 of the electrode, and the fluorescent lamp tube of the double-layer lamp tube is ensured not to burst and damage due to the expansion deformation caused by the temperature difference of the inner and outer layers of the fluorescent lamp tube. The inner and outer layers can also be made of glass of different materials, for example, the inner layer fluorescent tube 3 is made of borosilicate glass, so that the light attenuation of the brightness of the cold cathode fluorescent tube is reduced, and the service life of the tube is prolonged. The outer glass tube 2 is made of soda-lime glass, lead glass (commonly called soft glass), chrome glass, or the like. Of course, the electrodes 11 and 12 may be made of other materials, and they may be made of different two materials respectively, or may be made of the same material.

Fig. 5 is a schematic structural diagram of a cold cathode fluorescent lamp tube according to a fourth embodiment of the invention. Referring to fig. 5, the pipe ends of the inner and outer layers of the two pipes are not directly sealed together, but are connected together by the electrodes 1 disposed at the pipe ends of the two pipes. The elastic expansion-eliminating part of the electrode comprises electrodes which are respectively encapsulated on the tube end of the outer layer glass tube 2 and the tube end of the inner layer fluorescent tube 3, and a transition part connected between the two electrodes. Fig. 5A and 5B show the detailed structure of the electrode 1 in an enlarged scale, respectively, and include a tungsten electrode 14 encapsulated at the end of the outer glass tube 2, a tungsten electrode 15 encapsulated at the end of the inner fluorescent tube 3, and a transition portion such as a nickel wire 16 (see fig. 5A) or a nickel strap, a nickel alloy wire 17, etc. (see fig. 5B) connected (e.g., welded) between the two tungsten electrodes 14 and 15. Because the nickel wire or the nickel strap has good plasticity and is relatively soft, the electrode 1 with the elastic buffer structure is formed after being welded with the rigid tungsten electrode, the expansion deformation generated by the different temperatures of the inner layer and the outer layer is completely absorbed by the electrode 1, thereby ensuring that the double-layer fluorescent lamp tube does not burst due to the expansion stress, and completely eliminating the phenomenon of damage in use. Preferably, the length direction of the nickel wire 16 may be perpendicular to the length direction of the tungsten electrodes 14 and 15, i.e., as shown in fig. 5A, the tungsten electrodes 14 and 15 are welded to the upper and lower ends of the nickel wire 16, respectively, for example. And the nickel strap 17 may be formed in an arc shape, that is, as shown in fig. 5B, for example, tungsten electrodes 14 and 15 are welded to both ends of the arc-shaped nickel strap 17, respectively. The electrode 1 so formed has a sufficient degree of elasticity and cushioning along its length. The rigidity and strength of the tungsten electrodes 14 and 15 directly encapsulated at the ends of the two tubes are enough to support the inner fluorescent tube 3, so that the lighting position of the tube is not affected and the uniformity of the luminous brightness of the tube can be ensured.

Fig. 6 is a schematic structural view of a cold cathode fluorescent lamp tube according to a fifth embodiment of the present invention. Referring to fig. 6, the pipe ends of the inner and outer layers of the two pipes are connected together by electrodes 1 provided at the pipe ends of the two pipes. The electrode 1 is a tungsten electrode and fig. 6A shows an enlarged detailed structure of the electrode 1, in which diametrically opposite sides of the portion between the tube ends of the inner and outer layers are staggered (i.e., not parallel) to form notches 63 and 64, respectively. The opening depth of the notches 63 and 64 is about 1/10-8/10 of the diameter of the electrode 1, and the notches form an elastic buffer area of the electrode 1 in a staggered manner, so that the expansion deformation caused by the temperature difference between the inner layer and the outer layer can be completely absorbed, the double-layer fluorescent lamp tube is ensured not to burst due to expansion stress, and the damage phenomenon of the lamp tube is eliminated. The electrode 1 may also be made of Dumet wire electrode in combination with soda glass (i.e. soft glass) or Kovar electrode or molybdenum electrode in combination with molybdenum group glass.

Several examples of cold cathode fluorescent lamps designed according to the present invention are further set forth below.

Example 1

The inner layer fluorescent tube 3 of the straight tube type cold cathode fluorescent tube is made of borosilicate glass, the outer diameter is 1.8 mm, the length of the tube is 250 mm, the inner wall is coated with fluorescent powder with the color temperature of 6500 DEG k, a tungsten-nickel welding electrode is arranged at the tube end, and neon-argon mixed gas and mercury vapor are filled in the tube. The outer glass tube 2 is, for example, borosilicate glass, has an outer diameter of 2.6 mm, an inner diameter of 2.0 mm and a tube length of 255 mm, and has a tube end sealed to a tungsten electrode, as shown in fig. 2. The gap between the inner and outer layers is 0.1 mm, or there may be very small contact, and the gap is evacuated to a vacuum degree of 1-20 pa. The cold cathode fluorescent lamp employs a dedicated lighting circuit, and has an input voltage of, for example, 12 v, an input current of, for example, 0.32 a, a tube current of about 5.0 ma, and a tube voltage of about 600 v. The cold cathode fluorescent lamp tube can emit surface brightnessAbout 40000cd/m²The luminous flux of the lamp tube reaches more than about 30 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 70-100 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

Example 2

The inner layer fluorescent lamp tube 3 of the L-shaped cold cathode fluorescent lamp tube is made of borosilicate glass, the outer diameter is 1.8 mm, the tube length is 420 mm, the inner wall is coated with fluorescent powder with the color temperature of 7000 degrees k, a tungsten-nickel welding electrode is arranged at the tube end, and neon-argon mixed gas and mercury vapor are filled in the lamp tube. The outer glass tube 2 is, for example, borosilicate glass, has an outer diameter of 3.0 mm, an inner diameter of 2.1 mm and a tube length of 426 mm, and has its tube end sealed to a tungsten electrode, as shown in fig. 3. The gap between the inner and outer layers is 0.15 mm, or there may be very small contact, and the gap is evacuated to a vacuum degree of 1-20 pa. The cold cathode fluorescent lamp employs a lighting circuit having an input voltage of, for example, 12.5 v, an input current of, for example, 0.46 a, a tube current of about 7 ma, and a tube voltage of about 700 v. The surface luminance of the cold cathode fluorescent lamp tube of this example is about 42000cd/m²The luminous flux of the lamp tube reaches more than about 170 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 80-100 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

Example 3

The inner layer fluorescent lamp 3 of the straight tube type cold cathode fluorescent lamp is made of, for example, high borosilicate glass (expansion coefficient of about 3.2X 10)^-6V deg.C), external diameter is 1.8 mm, tube length is 140 mm, inner wall is coated with fluorescent powder whose colour temperature is 7000 deg.k, tube end is equipped with tungsten-nickel welding electrode, and interior of lamp tube is filled with neon-argon mixed gas and mercury vapour. The outer glass tube 2 is, for example, borosilicate glass (expansion coefficient of about 4.0X 10)^-6/° c), an outer diameter of 3.0 mm, an inner diameter of 2.1 mm, a tube length of 146 mm, and a tube end sealed to a tungsten electrode, as shown in fig. 3. The gap between the inner and outer layers is 0.15 mm, or there may be very small contact, and the gap is evacuated to a vacuum degree of 1-20 pa. The lighting circuit for cold cathode fluorescent lamp has input voltage of 13.4V and input current of 13.4VAt 0.19 amps, the tube current was about 5 milliamps and the tube voltage was about 370 volts. The surface luminance of the cold cathode fluorescent lamp tube of this example is about 42000cd/m²The luminous flux of the lamp tube reaches more than 60 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 70-100 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

Example 4

The inner layer fluorescent lamp tube 3 of the straight tube type cold cathode fluorescent lamp tube is made of borosilicate glass, the outer diameter is 1.8 mm, the tube length is 164 mm, the inner wall is coated with fluorescent powder with the color temperature of 6800 degrees k, a tungsten-nickel welding electrode is arranged at the tube end, and neon-argon mixed gas and mercury vapor are filled in the tube. The outer layer glass tube 2 is made of soda lime glass, the outer diameter is 2.6 mm, the inner diameter is 2.0 mm, the length of the tube is 172 mm, the tube end is sealed on a Dumet wire electrode, and the tube end electrodes of the inner layer and the outer layer are bent into a bow shape by the Dumet wire, as shown in figure 4. The gap between the inner and outer layers is 0.1 mm, or there may be very small contact, and the gap is evacuated to a vacuum degree of 1-20 pa. The cold cathode fluorescent lamp employs a lighting circuit having an input voltage of, for example, 8.5 v, an input current of, for example, 0.18 a, a tube current of about 1.5 ma, and a tube voltage of about 560 v. The surface brightness of the cold cathode fluorescent lamp tube of this embodiment is 22000cd/m²The luminous flux of the lamp tube reaches more than about 40 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 70-90 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

Example 5

The inner layer fluorescent lamp tube 3 of the straight tube type cold cathode fluorescent lamp tube is made of borosilicate glass, the outer diameter is 2.6 mm, the tube length is 240 mm, the inner wall is coated with fluorescent powder with color temperature of 6300 DEG k, the tube end is provided with a tungsten electrode, and neon-argon mixed gas and mercury vapor are filled in the tube. The outer layer glass tube 2 is, for example, borosilicate glass, has an outer diameter of 4.0 mm, an inner diameter of 2.9 mm and a tube length of 250 mm, the tube end is sealed on a tungsten electrode, and a nickel wire or a nickel band is arranged between the tube end electrodes of the inner and outer layers, as shown in fig. 5. The gap between the two tubes of the inner and outer layers is, for example, 0.15 mm, and may also be a very small contact, the gap beingVacuum degree is 1-20 pa. The cold cathode fluorescent lamp employs a lighting circuit having an input voltage of, for example, 11.3 v, an input current of, for example, 0.29 a, a tube current of about 6.0 ma, and a tube voltage of about 500 v. The cold cathode fluorescent lamp tube of this example can emit surface luminance of about 36000cd/m²The luminous flux of the lamp tube reaches more than about 130 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 80-100 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

Example 6

The inner layer fluorescent lamp tube 3 of the cold cathode fluorescent lamp tube is made of borosilicate glass, the outer diameter is 1.8 mm, the tube length is 164 mm, the inner wall is coated with fluorescent powder with the color temperature of 6800 degrees k, the end of the tube is provided with a tungsten electrode, and neon-argon mixed gas and mercury vapor are filled in the tube. The outer layer glass tube 2 is made of borosilicate glass, has an outer diameter of 2.6 mm, an inner diameter of 2.0 mm and a tube length of 174 mm, the tube ends are sealed on a tungsten electrode, and the tungsten wire between the tube ends of the inner layer and the outer layer is provided with a notch at 180 degrees respectively in an up-and-down symmetrical mode, as shown in fig. 6. The gap between the inner layer and the outer layer of the two tubes is 0.1 mm, for example, the inner layer and the outer layer of the two tubes of the glass can be partially contacted, the gap between the two tubes is vacuumized, and the vacuum degree is about 10 pa. The input voltage of the lighting circuit used for the cold cathode fluorescent lamp tube is, for example, 12 v, the input current is, for example, 0.23 a, the tube current is about 5.0 ma, and the tube voltage is about 420 v. The surface luminance of the cold cathode fluorescent lamp tube of this example is about 51000cd/m²The luminous flux of the lamp tube reaches more than about 80 Lm. The surface temperature of the inner layer fluorescent tube 3 is about 90-100 ℃, and the surface temperature of the outer layer glass tube 2 is slightly higher than the ambient temperature.

The various embodiments and examples of the invention described above are intended to aid in the understanding and appreciation of the cold cathode fluorescent lamp tube of the present invention, and various changes and modifications can be made therein by those skilled in the art without departing from the scope of the appended claims, and the invention is intended to encompass such changes and modifications.

Claims (10)

1. A cold cathode fluorescent lamp tube comprises an inner layer fluorescent lamp tube and an outer layer glass tube sleeved outside the inner layer fluorescent lamp tube, wherein the inner layer fluorescent lamp tube and the outer layer glass tube are arranged separately, a gap is arranged between the inner layer fluorescent lamp tube and the outer layer glass tube, and the cold cathode fluorescent lamp tube also comprises electrodes packaged at the tube ends of the inner layer fluorescent lamp tube and the outer layer glass tube.

2. The cold cathode fluorescent lamp of claim 1, in which the electrode is provided with an elastic expansion relief portion at a portion between the end of the inner fluorescent lamp tube and the end of the outer glass tube.

3. The cold cathode fluorescent lamp of claim 2, in which the elastically swollen portion of the electrode is a bent portion of the electrode.

4. The cold cathode fluorescent lamp of claim 2, in which the resilient bulge portion of the electrode comprises electrodes respectively encapsulated at the tube end of the outer layer glass tube and at the tube end of the inner layer fluorescent lamp, and a transition portion connected between the electrodes.

5. The cold cathode fluorescent lamp of claim 4, in which the two electrodes are tungsten electrodes, and the transition portion is a nickel wire, a nickel strap, or a nickel alloy wire strap connected between the two tungsten electrodes.

6. The cold cathode fluorescent lamp of claim 2, in which the resilient relief portion of the electrode comprises notches formed in the electrode on diametrically opposite sides of the electrode in a staggered manner.

7. The cold cathode fluorescent lamp of claim 6, in which the opening depth of the notch is 1/10-8/10 of the electrode diameter.

8. A cold cathode fluorescent lamp according to any of claims 1 to 7, wherein the inner layer fluorescent lamp and the outer layer glass tube are made of glasses having different coefficients of expansion.

9. The cold cathode fluorescent lamp of claim 8, in which the outer layer glass tube has a coefficient of expansion greater than the coefficient of expansion of the inner layer fluorescent lamp.

10. A cold cathode fluorescent lamp according to any of claims 1 to 7, wherein the inner layer fluorescent lamp and the outer layer glass tube are made of the same glass.