JPH05182638A - Cold cathode small-sized low pressure mercury discharge lamp - Google Patents

Abstract

PURPOSE:To provide a cold cathode small-sized low pressure mercury discharge lamp wherein startability is improved even at a low temperature in the dark. CONSTITUTION:In a cold cathode small-sized low pressure mercury discharge lamp which seals mercury and inert gas in a bulb 1, mounting a cold cathode electrode 3 sealed, to set a total surface area of the electrode 3 to 1000mm<2> or less a substance 7, in which a contact electrification quantity is positive relating to 44 to 74mum sized reduced iron powder, is provided so as to be exposed in discharge space. Since the substance 7, where the contact electrification quantity is positive relating to the reduced iron powder, provided so as to be exposed in the discharge space, increases an electron provided accidentally in the dark, startability can be improved.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a cold cathode electrode having a total surface area of 1000 mm ² Below, or the internal surface area of the discharge space is 30
00 mm ² In the following cold cathode small-sized low pressure mercury discharge lamp, the present invention relates to a means for improving starting characteristics in the dark.

[0002]

2. Description of the Related Art Generally, various discharge lamps cannot be smoothly ionized unless initial electrons that trigger discharge are present at the time of starting, and therefore starting is impossible or difficult. As the initial electrons that trigger the discharge, thermionic electrons,
There are photoelectrons, electrons emitted by high electric fields, and cosmic rays in the natural world. However, when the discharge lamp is left in a dark atmosphere where the light from the outside does not reach, there are no photoelectrons, so there are only cosmic rays and there is a tendency for starting to be difficult.

By the way, recently, a small liquid crystal display device has been developed as a color viewfinder of a VTR.
This is designed to illuminate a liquid crystal display panel with a size of about 23 mm × 18 mm from the back side with a backlight. As the backlight, a cold cathode fluorescent lamp with a small thermal load and excellent life characteristics is used. For example, a bent type cold cathode fluorescent lamp such as a straight tube type or a U-shaped type, or a flat type cold cathode. Fluorescent lamps are used.

A cold cathode fluorescent lamp is generally provided with a pair of cold cathodes facing each other in a glass bulb, and mercury and an inert gas are enclosed in the bulb and a fluorescent film is formed on the inner surface of the bulb. Is configured.

[0005]

However, since this type of lamp used as a backlight for the above-mentioned liquid crystal display is often used in a shielded housing or casing, there is little light entering from the outside. In addition, since it is a cold cathode, thermions are less likely to be emitted, and it is not possible to expect a sufficient supply of initial electrons required for starting discharge.

In addition, this type of lamp has been miniaturized due to its application, the inner surface area of the electrodes and the discharge space is small, and there is a probability that cosmic rays that come in from the outside can be captured and effectively used for discharge. small. From such a thing,
This type of cold-cathode compact fluorescent lamp has a problem that it takes a long time to start in a dark environment, in which the starting characteristic is not good in a low temperature atmosphere in which the discharge starting voltage becomes high due to a decrease in mercury vapor pressure.

A means for increasing the starting voltage can be considered for shortening the starting time, but increasing the starting voltage causes an increase in size of the lighting circuit, and a special insulating structure of the lighting circuit is required as a measure against withstand voltage. Therefore, there is a problem that the insulation becomes complicated and eventually becomes expensive.

The present invention has been made under these circumstances, and an object thereof is to provide a cold cathode small-sized low pressure mercury discharge lamp which is improved in startability even in darkness and at low temperature. ..

[0009]

The first aspect of the present invention is to enclose mercury and an inert gas in a bulb in which a cold cathode electrode is sealed so that the total surface area of the electrode is 1000 mm ² In the cold cathode small-sized low-pressure mercury discharge lamp as described below, the size is 44 to 74 μ.
It is characterized in that a substance having a positive contact charge amount with respect to the reduced iron powder of m, for example, at least one selected from MgO, ZnO, and Al ₂ O ₃ is provided so as to be exposed in the discharge space.

The second aspect of the present invention is to enclose mercury and an inert gas in a bulb in which a cold cathode electrode is sealed so that the surface area of the discharge space is 3000 mm ² In the following cold cathode small-sized low-pressure mercury discharge lamp, a substance having a positive contact charge amount with respect to the reduced iron powder having a size of 44 to 74 μm, for example, MgO, ZnO, A
At least one selected from l ₂ O ₃ is provided so as to be exposed in the discharge space.

[0011]

According to the present invention, the substance provided on the inner surface of the valve and having a positive contact charge amount with respect to the reduced iron powder increases the number of electrons that are accidentally present in the dark, so that the discharge is facilitated and the starting is started. It is possible to improve the sex.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIGS. The drawing shows a flat-type cold cathode fluorescent lamp used as a backlight of a liquid crystal display device applied to a color viewfinder of a VTR.

In FIGS. 1A and 1B,
Reference numeral 1 is a flat valve having a tubular shape with an oval cross section, for example, an oval tubular shape having a length L of 30 mm, a width W of 26 mm, and a height H of about 10 mm. The thickness t of the valve 1
Is about 1 mm. Therefore, the internal surface area of the valve 1 is about 2
070 mm ² Has become.

The flat valve 1 is air-tightly closed at both end openings by the flat stems 2 and 2. The stems 2 and 2 are so-called button stems because they are made of glass plates and have a flat plate shape. Cold cathodes 3 and 3 are attached to such flat plate-shaped stems 2 and 2, respectively. The cold cathodes 3 and 3 are made of, for example, a nickel plate, and are formed by applying a getter 4 made of zircon-aluminum on the front surface and attaching a mercury emission structure made of a mercury-titanium alloy (not shown) to the back surface.

The plate type cold cathodes 3 and 3 are
The surface area of each side is 150mm ² It is said that
The total surface area of the facing cold cathodes 3, 3 is 300 mm ² It is said that. These cold cathodes 3 and 3 are wells 5 and 5, respectively.
The wells 5 and 5 are joined to the stem 2,
2 is airtightly penetrated and led to the outside. Therefore, when the stems 2 and 2 are joined to the opening portions at both ends of the bulb 1, the cold cathodes 3 and 3 have a predetermined inter-electrode distance n, for example, 2
Opposite each other with 5 mm.

As shown in FIG. 1B, a coating 7 made of a substance having a positive contact charge amount with respect to the reduced iron powder is formed on the inner surface of the valve 1. The substance having a positive contact charge amount with respect to the reduced iron powder is, for example, Mg as shown in FIG.
A substance composed of at least one selected from O, ZnO, and Al ₂ O ₃ and having a contact charge amount (plus side) exceeding 0 μc / g with respect to reduced iron powder having a particle size of 44 to 74 μm. .. In this embodiment, the particle size is 0.01 to 0.1 μ.
m ₂ of alumina Al ₂ O ₃ is used.

In addition to the above MgO, ZnO, and Al ₂ O ₃ , BaO, CaO, SrO, PbO, HgO, etc. can be considered as the substance having a positive contact charge amount with respect to the reduced iron powder. Since the substance is inferior in chemical stability, it is difficult to handle and difficult to use. Therefore, MgO, ZnO, A
It is preferable to use at least one of l ₂ O ₃ . A phosphor coating 8 is formed on the inner surface of the coating 7 of such a charged substance, and the phosphor coating 8 is formed excluding both ends of the bulb 1. Therefore, in the vicinity of the cold cathodes 3 and 3, the coating film 7 of the charged substance is exposed in the discharge space.

The discharge space of the bulb 1 is filled with a predetermined amount of mercury and an inert gas containing at least one of argon, neon, xenon and crypt, for example, at about 50 Torr.

The flat type cold cathode fluorescent lamp having such a structure has an effective value of 800 V when a high frequency of 30 KHz sinusoidal wave is applied in an ambient temperature of 0 ° C.
Discharge started within 00 msec.

On the other hand, in the case of the conventional structure in which the coating 7 of the charged substance is not formed, the discharge was not started within 1 second unless the effective value of 1200 V was applied under the same conditions.
That is, when the coating film 7 of the charged substance is formed as in the above-mentioned embodiment, the discharge is started in a short time even if the starting voltage applied to the lamp is lowered, but in the lamp in which the coating film 7 of the charged substance is not formed, the discharge is started. If the voltage is not raised, the discharge will not start in a short time, and if the starting voltage is low, the discharge start time will be long. It is considered that the film 7 of the charged substance provided on the inner surface of the bulb 1 has a function of increasing the number of electrons that are accidentally present in the dark.

In the present invention, the total surface area of all the electrodes 3, that is, the total surface area is 1000 mm ^2. Below, or the internal surface area of the discharge space is 3000mm ² It is effective when applied to the following cold cathode small mercury vapor discharge lamps. That is, the total surface area of the electrode 3 is 1000 mm ² Below, or the internal surface area of the discharge space is 300
0 mm ² The small lamps listed below have a small surface area, so the probability that they can effectively use cosmic rays that come in from the outside for discharge is small.Therefore, this type of cold cathode small fluorescent lamp can be started in the dark and in a low-temperature atmosphere. The characteristics are not good. Therefore, when the present invention is applied to this type of lamp, the effect is remarkable. The result of an experiment when the surface area of the electrode 3 is changed will be described.

3 (A), (B) and (C) show the structures of the electrodes having different surface areas, respectively.
(A) shows that the surface area of the electrode 3a on one side is 300 mm ² by using two electrode plates. , Total surface area of electrodes on both sides is 600mm ² 3B, the surface area of the electrode 3b on one side is 500 mm ² by using three large electrode plates. , The total surface area of the electrodes on both sides is 1000 mm ² 3C, the surface area of the electrode 3c on one side is 1000 mm ² by using a cylindrical electrode having a partition plate housed inside the cylindrical body to increase the surface area. , Total surface area of electrodes on both sides is 2000mm ² This is the case. Electrode 3 shown in Figure 1 (total surface area 300 mm ² ) And (A) of FIG.
The results of measuring the lighting start time of the electrode shown in (C) are shown in Table 1 below.

[0023]

[Table 1]

The data shown in the above Table 1 shows that each test lamp was kept at room temperature for 7 days by repeating bright and dark (light is 1
000 lm for 12 hours, dark place for 12 hours), then put in a dark box and leave in the dark at a temperature of 0 ° C. for 24 hours, after which a voltage is applied between both electrodes of the lamp, and then a main discharge current flows. The time required for lighting up to is measured with a synchroscope. For each of the test lamps, 40 pieces were measured, and the respective averages are shown by stratification.

The applied voltage has a high frequency of 30 kHz and exhibits an effective value. The Al ₂ O ₃ coating was exposed to the discharge space on the bulb wall near the electrode, as shown in FIG. 1 (B).

It can be seen from Table 1 that the higher the applied voltage is, the easier the lamp is to start, and the larger the total surface area of the electrodes, the easier the lamp is to start. Especially, the total surface area of the electrode is 2000 mm ² In the above case, starting is easy. However, due to the miniaturization of the lamp, the total surface area of the electrode is 1000 mm ² The following restrictions must be applied, and in such cases Al ₂ O
₃ of the film formed was lamps, as compared to a lamp that does not form a coating of Al ₂ O _3, it is recognized that clearly improved startability.

In the above embodiment, the film 7 of the charged substance is used.
In the present invention, the coating 7 of the charged substance is formed only in the vicinity of the cold cathodes 3 and 3 as in the second embodiment shown in FIG. It may be formed by being exposed to the discharge space. Further, as in the third embodiment shown in FIG. 5, the coating film 7 of the charged substance may be formed on the inner surfaces of the stems 2 and 2. Further, although not shown, the coating film 7 of the charged substance may be formed on the back surface of the cold cathode 3.

Further, the powder of the charged substance is mixed with the phosphor or mixed with the phosphor powder, and this is coated as a phosphor coating on the inner surface of the bulb. From this phosphor coating, a part of the charged substance is applied. The powder may be exposed in the discharge space. Further, the invention is not limited to the flat fluorescent lamp, but may be a straight tube fluorescent lamp or a bent fluorescent lamp.

That is, in the fourth embodiment shown in FIG.
1 shows a W-shaped cold cathode fluorescent lamp used for a backlight for color liquid crystals. In the figure, reference numeral 60 is a W-shaped valve having a valve diameter of 8.5 mm and a valve length of 500 mm, and both ends thereof are closed by stems 61, 61. Wells 62 and 62 are sealed to the stems 61 and 61, and cylindrical wells 63 and 63 are connected to the wells 62 and 62, respectively. The cold cathodes 63, 63 are made of nickel or the like, and the surface area of the electrode on one side is 420 mm.
² And the total area of the electrodes on both ends is 840 mm ^2. It is said that. A phosphor coating 64 is formed on the inner surface of the bulb 60 as shown in FIG.
A film 65 of ₂ O ₃ is formed so as to be exposed in the discharge space. Even in the case of the bent type fluorescent lamp having such a configuration, the coating 65 of the charged substance increases the electrons that are accidentally present in the dark, so that the starting characteristic is improved.

The fifth embodiment shown in FIG. 8 shows a horseshoe (Ω) type cold cathode fluorescent lamp used as a light source for meter display. In the figure, reference numeral 80 is a W-shaped valve having a valve diameter of 9.5 mm and a valve length of 200 mm, and both ends thereof are closed by stems 81 and 81. Stem 8
Wells 82 and 82 are sealed to 1 and 81, respectively, and these wells 82 and 82 are chevron-shaped cold cathodes 8 respectively.
3, 83 are connected. The cold cathodes 83, 83 are made of nickel or the like, and the surface area of the electrode on one side is 200 mm ² And the total area of the electrodes on both ends is 400 mm ² It is said that. As shown in FIG. 9, a phosphor coating 84 is formed on the inner surface of the bulb 80, and particles 85 of a charged substance such as MgO or Al ₂ O ₃ are mixed in the phosphor coating 84. Has been done. That is, particles of a charged substance such as MgO and Al ₂ O ₃ are sprinkled on the phosphor powder and mixed together, and in this state a phosphor coating is formed. Part of it is exposed to the discharge space. Even in the case of the bent type fluorescent lamp having such a structure, the starting characteristics are improved by the action of the particles 85 of the charged substance.

Further, a sixth embodiment shown in FIG. 10 shows a straight tube cold cathode fluorescent lamp used for a liquid crystal backlight. In the figure, 90 is a straight tube type valve, and both ends are closed by sealing portions 91, 91 (only one end is shown). Wells 92 are sealed to the sealing portion 91, and a flat cold cathode 83 is connected to the wells 92. The cold cathode 93 is made of nickel or the like,
The surface area of the electrode on one side is 100 mm ² And the total area of the electrodes on both ends is 200 mm ² It is said that. And the valve 90
A phosphor coating 94 is formed on the inner surface of the phosphor, and particles 95 of a charged substance such as Al ₂ O ₃ are mixed in the phosphor coating 94. Particles 95 of a charged substance such as Al ₂ O ₃ are mixed with the phosphor powder to form a phosphor coating, so that part of the charged substance particles 95 is exposed in the discharge space. Even in the case of the fluorescent lamp having such a configuration, the starting characteristics are improved by the action of the particles 95 of the charged substance.

Furthermore, according to the present invention, the inner surface area of the discharge space is 3000 mm ² It is also effective when applied to the following small mercury vapor discharge lamps. That is, the inner surface area of the discharge space is 3000 mm
² The following lamps are also small and have a low probability of catching cosmic rays coming in from outside. For this reason, this type of cold cathode small fluorescent lamp does not have a good starting characteristic in the dark and in a low temperature atmosphere. Therefore, when the present invention is applied to this type of lamp, its effect is remarkable.

[0033]

As described above, according to the present invention, the substance provided on the inner surface of the valve and having a positive contact charge amount with respect to the reduced iron powder has a function of increasing the number of electrons accidentally present in the dark. Therefore, even if the lamp has a small surface area of the electrode or the surface area of the discharge space, the starting is facilitated and the starting voltage can be lowered to shorten the discharge start time.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, FIG. 1A is an exploded perspective view of a flat cold cathode fluorescent lamp, and FIG. 1B is a sectional view thereof.

FIG. 2 is a diagram showing electronegativity of metal ions.

FIG. 3 shows structures of cold cathodes having different surface areas,
(A) is a perspective view of a cold cathode using two electrode plates,
(B) is a perspective view of a cold cathode using three electrode plates,
FIG. 3C is a perspective view of a cold cathode using a cylindrical electrode.

FIG. 4 is a sectional view of a flat type cold cathode fluorescent lamp showing a second embodiment of the present invention.

FIG. 5 is a sectional view of a flat type cold cathode fluorescent lamp showing a third embodiment of the present invention.

FIG. 6 is a perspective view of a W-shaped cold cathode fluorescent lamp showing a fourth embodiment of the present invention.

FIG. 7 is a sectional view of an end portion of the lamp according to the embodiment.

FIG. 8 is a perspective view of a horseshoe-shaped cold cathode fluorescent lamp showing a fifth embodiment of the present invention.

FIG. 9 is a sectional view of an end portion of the lamp according to the embodiment.

FIG. 10 is a sectional view of an end portion of a straight tube type cold cathode fluorescent lamp showing a sixth embodiment of the present invention.

[Explanation of symbols]

1, 60, 80, 90 ... Bulb, 2, 61, 81 ... Stem, 3, 63, 83, 93 ... Cold cathode, 5, 62, 82,
92 ... wells, 7,65 ... coating of charged material, 8,6
4, 84, 94 ... Fluorescent film, 85, 95 ... Particles of charged substance.

Claims (6)

[Claims] 1. A bulb in which a cold cathode electrode is sealed is filled with mercury and an inert gas, and the total surface area of the electrode is 1000 mm.
² The cold cathode small-sized low-pressure mercury discharge lamp as described below, characterized in that the discharge space is provided so as to expose a substance having a positive contact charge amount with respect to reduced iron powder of 44 to 74 μm. Low pressure mercury discharge lamp. 2. The cold cathode miniature low-pressure mercury discharge according to claim 1, wherein the substance having a positive contact charge amount with respect to the reduced iron powder is located near the electrode and exposed to the discharge space. Electric light. 3. The substance having a positive contact charge amount with respect to the reduced iron powder is at least one selected from MgO, ZnO and Al ₂ O _3. The cold cathode compact low-pressure mercury discharge lamp described. 4. An internal surface area of the discharge space of 3000 mm is obtained by enclosing mercury and an inert gas in a bulb in which a cold cathode electrode is sealed.
² The cold cathode small-sized low-pressure mercury discharge lamp as described below, characterized in that the discharge space is provided so as to expose a substance having a positive contact charge amount with respect to reduced iron powder of 44 to 74 μm. Low pressure mercury discharge lamp. 5. The cold cathode miniature low-pressure mercury discharge according to claim 1, wherein the substance having a positive contact charge amount with respect to the reduced iron powder is located near the electrode and exposed to the discharge space. Electric light. 6. The substance according to claim 4, wherein the substance having a positive contact charge amount with respect to the reduced iron powder is at least one selected from MgO, ZnO, and Al ₂ O _3. The cold cathode compact low-pressure mercury discharge lamp described.