JP2004158468A - Low-pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-pressure discharge lamp having an emitter adhered on an inner surface of a sleeve, capable of making an emitter efficiency last long by restraining the emitter from exfoliation and fall-off. <P>SOLUTION: The electrodes 2 having the sleeve 6 on the inner surface of which the emitter 5 is adhered, are mounted on both end parts of a bulb 1. The sleeve 6 is made of nickel or a nickel alloy with a Vickers hardness of 160 or less, and the emitter 5 is made of diamond. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a low-pressure discharge lamp used for a backlight of a liquid crystal panel, a light source for general illumination, an ultraviolet light source, and the like, and a method for manufacturing the same.

  Such a conventional low-pressure discharge lamp, for example, a cold cathode fluorescent lamp, is known in which an emitter is attached to the inner surface of a hollow electrode in order to prevent the emitter from scattering due to ion bombardment during lighting. (JP-A-64-33844).

  As the emitter, a mixed oxide, which is obtained by activating and decomposing a mixed carbonate of barium, strontium, calcium or the like by heating, is usually used.

  However, in general, in the cold cathode fluorescent lamp, the opening diameter of the hollow electrode is only a few millimeters. For example, when the emitter material is injected into the electrode and the emitter material is applied to the inner surface thereof, the influence of the surface tension causes the after-application of the emitter material. The thickness of the emitter becomes non-uniform (the maximum thickness is at least 5 times the average thickness). The uneven thickness of the emitter and the thermal contraction of the emitter during the thermal decomposition (activation) of carbonate to oxide cause the thicker portion of the emitter to peel off from the electrode. The emitter falls off from the electrode due to vibration during transportation of the lamp or the like, and there is a problem in that the emitter effect of reducing the cathode drop voltage occurs after lighting for several thousand hours.

  The present invention has been made in order to solve such a problem, and the emitter attached to the inner surface of the sleeve suppresses the peeling and falling off of the emitter from the electrode, and a low pressure capable of maintaining the emitter effect for a long time. A discharge lamp is provided.

  In the low-voltage discharge lamp of the present invention, electrodes having a sleeve with an emitter attached to the inner surface are attached to both ends of the bulb, and the sleeve is made of nickel or a nickel alloy having a Vickers hardness of 160 or less.

  With this configuration, even when the emitter attached to the inner surface of the sleeve is thermally decomposed (activated) from a carbonate to an oxide, the emitter can be prevented from peeling or falling off even if it thermally contracts.

  As described above, according to the present invention, the emitter attached to the inner surface of the sleeve can be prevented from peeling off or falling off from the electrode due to thermal contraction of the emitter when the emitter is activated. It is possible to provide a low-pressure discharge lamp that can be maintained for a long time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a cold cathode fluorescent lamp according to a first embodiment of the present invention includes a bulb 1 made of, for example, borosilicate glass, and electrodes 2 attached to both ends of the bulb 1. I have. Since both ends of the cold cathode fluorescent lamp have the same structure, only one end is illustrated and described.

  The bulb 1 has a total length of 90 mm, an outer diameter of 1.8 mm, and an inner diameter of 1.4 mm.

  The end of the bulb 1 is sealed by a glass bead 3.

A phosphor 4 is applied to the inner surface of the bulb 1. The phosphor 4 is composed of, for example, a three-wavelength phosphor of (Y, Eu) ₂ O ₃ , (La, Ce, Tb) PO ₄ , and (Ba, Eu) MgAl ₁₀ O ₁₇ .

  In addition, a mixed gas of neon and argon of 11 kPa is sealed in the bulb 1 together with a predetermined amount of mercury.

  The electrode 2 has a bottomed cylindrical sleeve 6 having an emitter 5 attached to an inner surface and a part of an outer surface, and an inner lead wire 7 integrated with the bottom of the sleeve 6 by, for example, resistance welding. ing. The distance between the other end and the electrode 2 (not shown) is 80 mm.

The emitter 5 includes an alkaline earth metal (magnesium, calcium, strontium, barium), an alkaline earth metal oxide, an alkali metal (lithium, sodium, potassium, cesium), an alkali metal oxide, an electron-emitting substance (lanthanum). , Yttrium, lanthanum barium (LaB ₆ ), carbon), or an oxide mainly containing at least one oxide of this electron-emitting substance.

  The sleeve 6 has an outer diameter of 1.0 mm, an inner diameter of 0.8 mm, and a length of 3.0 mm, and has a heat resistance higher than the activation temperature of the emitter 5 (for example, 1100 ° C.), such as nickel, stainless steel, and cobalt. , Iron or nickel alloy. However, when an emitter (barium aluminate, cesium compound, or the like) that does not need to be activated is used, a metal having a heat resistance higher than the exhaust temperature (for example, 500 ° C.) in an exhaust process during a normal manufacturing process is used. Good.

  One through hole 8 having a diameter of 0.2 mm is provided on the side wall at a position 2.7 mm from the open end of the sleeve 6. By providing the through-holes 8 near the bottom in this manner, in the case of the suction coating described later, the amount of application (deposition) of the emitter can be increased, so that the emitter effect described later can be maintained for a longer time. it can.

  The inner lead wire 7 has an outer diameter of 0.6 mm and is made of tungsten or the like. The internal lead wire 7 extends out of the bulb 1 through the glass bead 3 and is connected to an external lead wire 9 made of nickel having an outer diameter of 0.4 mm.

  Next, a method for manufacturing such a cold cathode fluorescent lamp will be described.

  The internal lead wire 7 and the bottomed cylindrical sleeve 6 provided with the through hole 8 in the side wall are integrated in advance.

  Then, the tip of the opening side of the sleeve 6 is immersed in an emitter material liquid (not shown) having a specific gravity of 1.2, and the emitter material liquid permeates the inner surface of the sleeve 6 from the opening of the sleeve 6 by a capillary phenomenon. During this permeation, the air in the sleeve 6 escapes from the through hole 8.

  In this manner, the emitter material (not shown) is applied to the inner surface of the sleeve 6 (hereinafter, referred to as suction application).

In the emitter material liquid, powder of, for example, barium carbonate (BaCO ₃ ) and strontium carbonate (SrCO ₃ ) is mixed in a molar ratio of BaCo ₃ : SrCO ₃ = 2: 1 in 20 l of a butyl acetate liquid and nitric cellulose mixed solution. , A mixed carbonate suspension prepared by mixing 10 kg of the mixed powder.

  Next, the sleeve 6 is pulled up from the emitter material liquid and air-dried in the air. Then, a part of the emitter material attached to the outer surface of the sleeve 6 is wiped off with a cloth. However, the entire inner surface of the sleeve 6 is coated with the emitter material, and the emitter material liquid also penetrates into the through-hole 8, so that the through-hole 8 is closed with the emitter material.

  The applied emitter material is placed in a reducing furnace in an argon atmosphere (internal temperature: about 1100 ° C.), and the emitter material is thermally decomposed and activated.

  Thus, the emitter 5 is attached to the sleeve 6 of the electrode 2. Thereafter, using the electrode 2, a cold cathode fluorescent lamp (hereinafter, referred to as a product A of the present invention) is manufactured by a normal manufacturing method.

  Next, using the product A of the present invention, the emitter effect of lowering the cathode drop voltage was examined.

  Therefore, first, a vibration test was performed on the product A of the present invention, and the falling rate (%) of the emitter 5 from the electrode 2 was examined.

The dropout rate referred to here means that the inside of the bulb 1 is visually observed, and if at least one piece of the emitter having a drop of 0.25 mm ³ or more is present in the bulb 1, it is regarded as “defective”, and the “total number of samples” The ratio of the number of "defective products" is shown.

In the vibration test, two vibrations of a lamp having a frequency of 10 Hz to 20 Hz and an amplitude of 2 mm and a vibration of a frequency of 22 Hz to 500 Hz and an acceleration of 14.7 m / s ² were measured in the X and Y directions. , In the Z direction for 30 minutes each.

  For comparison, the same vibration test as that of the product A of the present invention was performed on a cold cathode fluorescent lamp having the same configuration as that of the product A of the present invention (hereinafter referred to as comparative product A) except that there was no through hole. The dropout rate (%) of the emitter from the electrode was examined.

  The sample number of the product A of the present invention and the sample of the comparative product A are each 1000.

  In addition, sleeves made of nickel (Vickers hardness 180) were used for the product A of the present invention and the comparative product A.

  As a result of the vibration test, in the product A of the present invention, the falling rate of the emitter 5 was 0%. On the other hand, in Comparative product A, the dropout rate of the emitter was 30%.

  The reason for this is that, in the case of the product A of the present invention, the film thickness of the emitter 5 deposited on the inner surface of the sleeve 6 is more uniform than that of the product A of the comparative example. It is considered that the emitter 5 does not peel even if the emitter 5 thermally contracts during the activation of the emitter 5.

  Further, the emitter effect of the product A of the present invention after the above-mentioned vibration test and the comparative product A were confirmed.

  Each of the product A of the present invention and the comparative product A was lit (lamp current: 5 mA, lit frequency: 60 kHz) using a high-frequency lighting circuit (not shown) under conditions of an ambient temperature of 25 ° C. and no wind, and a lamp voltage (Vrms). When the change with time was observed, the result as shown in FIG. 2 was obtained. In addition, the result of the product A of the present invention was indicated by a symbol A, and the result of the comparative product A was indicated by a symbol B.

  As is clear from FIG. 2, in the product A of the present invention, the lamp voltage was kept almost constant from the beginning of lighting to the end of lighting for 10,000 hours, that is, 220 Vrms (effective value). On the other hand, in Comparative product A, the lamp voltage gradually increased, and after lighting for 5000 hours, the lamp voltage increased to 280 Vrms. This is because the emitter effect of the comparative product A was lost due to the emitter dropping off, and the emitter effect of the product A of the present invention was not dropped, so that the emitter effect could be maintained for a long time.

  As described above, according to the configuration of the cold cathode fluorescent lamp according to the first embodiment of the present invention, the application of the emitter material to the inner surface of the sleeve 6 can be performed by suction coating, so that the inner surface of the sleeve 6 5 can be deposited so as to have a uniform film thickness, and it is possible to prevent the emitter 5 from peeling off and falling off from the electrode 2 (sleeve 6) due to thermal contraction of the emitter 5 when the emitter 5 is activated. it can. As a result, the emitter effect can be maintained for a long time. Further, since the application of the emitter material to the inner surface of the sleeve 6 can be absorbed and applied, the emitter 5 can be easily applied to the inner surface of the sleeve 6.

By the way, it is preferable that the area of the above-mentioned through hole 8 is 0.01 mm ² or more and 0.25 mm ² or less. Hereinafter, the reason will be described.

A cold cathode fluorescent lamp having the same configuration as the product A of the present invention was prepared except that the area of the through hole 8 was variously changed in the range of 0.005 mm ² or more and 0.4 mm ² or less. A vibration test was performed under the same conditions as those described above, and the dropout rate of the emitter 5 from the electrode 2 and the success rate of the suction application were examined. The results shown in Table 1 were obtained.

  The number of samples is 1000 each.

  In addition, the success rate of siphoning application as used herein indicates the ratio of the number of samples in which it is impossible or extremely difficult to siphon the emitter material into the sleeve with respect to the total number of samples.

As shown in Table 1, when the area of the through hole 8 was 0.25 mm ² or less, the dropout rate of the emitter 5 was 0%. On the other hand, if the area of the through-holes is more than 0.25 mm ^2, for example, 0.30 mm ² in the emitter of the dropout rate of 10%, the 0.40 mm ² dropout rate was 20%. This is because, when the area of the through hole exceeds 0.25 mm ² , the part of the emitter that enters the through hole becomes a thick part of the emitter, and that part falls off during activation of carbonate to oxide. It is thought that it is easy to do.

When the area of the through-hole 8 was 0.01 mm ² or more, the success rate of the suction application was 100%. On the other hand, is less than 0.01 mm ² area of the through-holes, for example, 0.007 mm ² in wicking coating success rate of 90%, applied success rate sucked up at 0.005 mm ² was 80%. This is considered to be because if the area of the through-hole is less than 0.01 mm ^2, the air from the through-hole becomes poor at the time of the suction application, so that the emitter material liquid cannot be sucked up smoothly.

Therefore, by defining the area of the through hole 8 to be 0.01 mm ² or more and 0.25 mm ² or less, the through hole 8 functions sufficiently as a hole for air to smoothly suck up the emitter material liquid into the sleeve 6. In addition, it is possible to prevent a portion of the emitter 5 that is contained in the through hole 8 from falling off.

  In the above embodiment, the case where the through hole 8 is provided near the bottom side of the side wall of the sleeve 6 has been described. However, for example, the through hole 8 may be provided at the bottom of the sleeve except for the connection portion with the internal lead wire. Good.

  Next, as shown in FIG. 3, a cold cathode fluorescent lamp according to a second embodiment of the present invention (hereinafter referred to as a product B of the present invention) includes a cylindrical sleeve 10 having one end narrowed down and a bottomless cylindrical sleeve 10. Has the same configuration as the cold cathode fluorescent lamp according to the first embodiment of the present invention except that electrodes 11 integrated with the internal lead wires 7 are attached to both ends of the bulb 1. ing. Since both ends of the cold cathode fluorescent lamp have the same structure, only one end is illustrated and described.

  The sleeve 10 has a maximum outer diameter of 1.1 mm, a maximum inner diameter of 0.9 mm, and a total length of 3 mm. The inner diameter of the narrowed portion at one end is 0.6 mm, which is almost the same as the outer diameter of the internal lead wire 7. , Its length is 1 mm.

  A part of the inner lead wire 7 made of tungsten or the like having an outer diameter of 0.6 mm is inserted into the narrowed portion of the sleeve 10, and the narrowed portion is crimped, so that the inner lead wire 7 and the sleeve 10 are compressed. Are integrated.

  During this integration, the internal lead wire 7 and the sleeve 10 are pressure-bonded so that there is no gap. Therefore, since the end surface of the internal lead wire 7 corresponds to the bottom surface of the sleeve 6 used for the product A of the present invention, the electrode 11 used for the cold cathode fluorescent lamp according to the present embodiment is different from that of the first embodiment. It can be said that the outer shape is almost the same as the electrode 2 used for a certain cold cathode fluorescent lamp.

  One through hole 8 having a diameter of 0.2 mm is provided on the side wall at a position 1.7 mm from the open end of the sleeve 10.

  In the cold cathode fluorescent lamp according to the second embodiment of the present invention as described above, similarly to the cold cathode fluorescent lamp according to the first embodiment of the present invention, the emitter 5 is provided on the inner surface of the sleeve 10. Since the coating can be performed by suction coating, the emitter 5 can be applied to the inner surface of the sleeve 10 so as to have a uniform thickness, and the emitter 5 is thermally shrunk when the emitter 5 is activated. From the electrode 11 (sleeve 10). As a result, the emitter effect can be maintained for a long time.

  Next, in a cold cathode fluorescent lamp according to a third embodiment of the present invention (hereinafter referred to as the present product C), an electrode (not shown) having a sleeve made of nickel having a Vickers hardness of 160 or less is provided with a bulb (not shown). It has the same configuration as the cold cathode fluorescent lamp according to the first embodiment of the present invention except that it is attached to both ends (not shown).

  The Vickers hardness of the sleeve was reduced by annealing for 5 minutes in a rare gas atmosphere or vacuum at about 800 degrees, that is, by annealing. Under the above conditions, the Vickers hardness of the sleeve is 150.

  Here, with respect to the product C of the present invention, the startability in a dark place was examined.

  The dark place is a space where the ambient illuminance is 0.1 lux or less.

  In conducting the above examination, the peeling rate (%) of the emitter from the electrode and the starting probability (%) were examined.

  In addition, the peeling rate referred to here means that the emitter attached to the inner surface of the sleeve is observed with a microscope or the like, and the one in which the emitter has been peeled from the electrode by 0.1 mm or more is regarded as a "defective product". The ratio of the number of "defective products" is shown.

  The starting probability here indicates the ratio of the number of started lamps to the total number of samples.

  First, a cold roll of the present invention C having the same configuration as that of the present invention C except that a sleeve made of nickel (Vickers hardness 180) without annealing was used, and the sleeve of the present invention C having a Vickers hardness of 150 was used. Each of 1,000 cathode fluorescent lamps (hereinafter referred to as comparative product B) was manufactured, and the peeling rate of the emitter from each electrode was examined.

  As a result, in the product C of the present invention, the peeling rate of the emitter was 0%. On the other hand, in Comparative Product B, the peeling rate was 30%. This is because, in the case of the comparative product B, there is a distortion in the nickel used as the sleeve material, and even if the emitter is applied to the inner surface of the sleeve so as to have a uniform thickness, the carbonate is caused by the distortion. This is considered to be due to cracks and the like occurring in the deposited emitter and activation during the activation to the oxide salt. On the other hand, in the case of the product C of the present invention, by annealing the sleeve, the distortion is reduced, that is, the Vickers hardness is reduced, and the peeling of the emitter can be suppressed.

  Next, the output voltage and the output time of the lighting circuit (not shown) in the product C of the present invention (emitter peeling rate of 0%) and the comparative product B (emitter peeling rate of 30%) are variously changed to obtain a dark place. As a result, the starting probability was as shown in Table 2.

  As shown in Table 2, in the product C of the present invention, when the output voltage is 1000 Vrms and the output time is 2000 msec, the output voltage is 1000 Vrms and the output time is 500 msec, and the output voltage is 700 Vrms and the output time is 500 msec. In each case, the probability of starting in a dark place was 100%.

  On the other hand, in the comparative product B, when the output voltage was 1000 Vrms and the output time was 2000 msec, the starting probability in a dark place was 100%, but when the output voltage was 1000 Vrms and the output time was 500 msec, Was 90%, and when the output voltage was 700 Vrms and the output time was 500 msec, the starting probability in a dark place was 70%.

  Therefore, it was confirmed that the product C of the present invention can reliably start even if the output time is shorter than that of the comparative product B, that is, it is excellent in startability in a dark place. This is considered to be because, in the case of the product C of the present invention, since the peeling rate was 0%, the electron emission efficiency was higher than that in Example 1 in which the peeling rate was 30%.

  According to the configuration of the cold cathode fluorescent lamp according to the third embodiment of the present invention as described above, in addition to the effect of the cold cathode fluorescent lamp according to the first embodiment of the present invention, in addition to Since the peeling of the emitter can be suppressed, the photoelectric effect of the emitter can be sufficiently exerted.Even with a slight light irradiation, enough electrons are emitted from the electrode to start the discharge, and Startability can be improved.

  In the third embodiment, the case where the sleeve made of nickel is used has been described. However, the same effect can be obtained even when the sleeve made of a nickel alloy is used.

  Next, a cold cathode fluorescent lamp according to a fourth embodiment of the present invention (hereinafter referred to as product D of the present invention) has an electrode (not shown) having a sleeve on which an emitter made of diamond is adhered on the inner surface. It has the same configuration as the cold cathode fluorescent lamp according to the first embodiment of the present invention except that it is attached to both ends of a bulb (not shown).

  The product D of the present invention is manufactured by the same manufacturing method as that of the cold cathode fluorescent lamp according to the first embodiment, and an emitter material liquid obtained by melting diamond fine particle powder having a particle diameter of several nm in a butyl acetate solution. Was used.

  The thickness of the emitter is 6 μm to 12 μm.

  Next, with respect to the product D of the present invention, the remaining amount of the emitter accompanying lighting was examined.

  The product D of the present invention was lit using a high-frequency lighting circuit (lamp current 10 mA, lighting frequency 100 kHz) under conditions of an ambient temperature of 25 ° C. and no wind, and the remaining amount of the emitter after 1000 hours of lighting was examined. The following results were obtained.

  For comparison, it has the same configuration as the cold cathode fluorescent lamp according to the first embodiment of the present invention except that an emitter made of a mixture of barium oxide and strontium oxide is attached to the inner surface of the sleeve. For the cold cathode fluorescent lamp (hereinafter referred to as comparative product C), the remaining amount of the emitter after lighting for 1000 hours was examined under the same conditions as in the case of the product D of the present invention.

  Here, the remaining amount of the emitter refers to the sum of the amount of the emitter attached to the inner surface of the bulb and the amount of the emitter attached to the sleeve after the lapse of 1000 hours of lighting. It shows the ratio of the emitter amount.

  As a result, in the product D of the present invention, the remaining amount of the emitter after lighting for 1000 hours was 97%. On the other hand, in the comparative product C, the remaining amount of the emitter after lighting for 1000 hours was 85%. This is considered to be because the emitter made of diamond used in the product D of the present invention is less likely to sputter due to ion bombardment at the time of lighting than the emitter used in the comparative product C.

  According to the configuration of the cold cathode fluorescent lamp according to the fourth embodiment of the present invention as described above, the emitter can be prevented from being sputtered due to ion bombardment at the time of lighting. Can last for hours.

  In each of the above embodiments, the case where one through hole 8 is provided has been described. However, the same effect as described above can be obtained by providing two or more through holes 8.

Front sectional view showing one end of a cold cathode fluorescent lamp according to a first embodiment of the present invention. Diagram showing the relationship between elapsed lighting time and lamp voltage Front sectional view showing one end of a cold cathode fluorescent lamp according to a second embodiment of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Bulb 2,11 Electrode 5 Emitter 6,10 Sleeve 8 Through hole

Claims (2)

An electrode having a sleeve with an emitter attached to the inner surface is attached to both ends of the bulb, wherein the sleeve is made of nickel or a nickel alloy having a Vickers hardness of 160 or less. 2. The low pressure discharge lamp according to claim 1, wherein said emitter is made of diamond.

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