JPH06314562A - Fluorescent lamp and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a fluorescent lamp which is hard to break, has a small non-luminous portion at each end, and is easy to manufacture by reducing the pressure difference between inside and outside the lamp. CONSTITUTION:Mixed gases including xenon by 20 to 200Torr and the rest other rare gases are sealed by 400 to 700Torr in a fluorescent lamp 1 having a phosphor 3 on the inside wall of a glass bulb 2 and one or more pairs of conductors on the outside wall of the bulb. High-pressure gases can thus be sealed in the lamp without varying the discharge voltage and brightness characteristic of the lamp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp for display used for illuminating originals used in information equipment such as facsimiles, copying machines, image readers, and for display devices such as large-sized display devices and electronic bulletin boards. It is a thing.

[0002]

2. Description of the Related Art In recent years, fluorescent lamps have been used as a light source for illuminating originals in information equipment such as facsimiles, copying machines and image readers, and as a display light source for large color display devices. In these applications, the lamp is required to be smaller, have higher brightness, have longer life, and have higher reliability. Conventional fluorescent lamps are subject to many restrictions because they have electrodes inside the lamps. Therefore, fluorescent lamps that do not have electrodes inside the lamps have been considered.

5 (a), 5 (b) and 5 (c) are a perspective view, a sectional view and a lighting device thereof showing a conventional fluorescent lamp having an external electrode as disclosed in, for example, Japanese Patent Laid-Open No. 3-225745. FIG. 1 is a circuit diagram showing a conventional fluorescent lamp, 2 a straight glass tube having a rare gas mainly containing xenon gas sealed therein, and 3 a glass bulb 2.
The phosphor layer 4 formed on the inner surface of the lamp 4 is a light output part for irradiating the light generated inside the lamp to the outside of the lamp, and 5a and 5b are made of aluminum foil on both sides along the light output part 4 and have a predetermined width Strip-shaped external electrodes, which are closely attached to the outer wall of the glass bulb 2 for almost the entire length and are arranged to face each other, 6 is the external electrode 5
It is a transparent insulating film of a silicon resin coated on the glass bulb 2 including a and 5b. Reference numeral 7 is a sealing glass in which both ends of the glass bulb 2 are hermetically sealed. Also, 8
Is a high-frequency lighting circuit that lights the conventional fluorescent lamp 1, and 9 is an AC power supply that is connected to the external electrodes 5a and 5b through the high-frequency lighting circuit 8 and applies a predetermined high-frequency voltage.

A high frequency lighting circuit 7 is provided on the external electrodes 5a and 5b.
Therefore, when a sinusoidal AC voltage is applied, the external electrodes 5a, 5
Discharge of xenon gas is generated in the inner space of the glass bulb 2 sandwiched by b, ultraviolet rays are generated by the discharge of the xenon gas, and the phosphor layer 3 formed on the inner surface of the glass bulb 2 is discharged.
Is excited to generate visible light, and the light is emitted from the light output unit 4 to the outside of the lamp.

Further, in our research, in a fluorescent lamp in which a rare gas is enclosed in such a glass bulb and an external electrode is provided on the outer wall, a rare gas is formed on the surface of the electrode portion inside the glass bulb due to discharge between the electrodes. It is known that the excimer is generated, and the fluorescent substance is excited by the ultraviolet rays emitted from the excimer to irradiate visible light. Further, in order to efficiently obtain higher brightness, it is known that the area of the external electrodes should be increased and the distance between the electrodes should be shortened. Such a fluorescent lamp is disclosed in Japanese Patent Application No. 4-2365.
No. 3 is shown.

[0006]

Since the conventional fluorescent lamp as described above discharges between the external electrodes via the glass bulb which is a dielectric, it is preferable that the glass bulb be thin.
However, if the glass bulb is made thin, it is easily damaged due to the pressure difference between the pressure inside the bulb and the atmospheric pressure. In addition, it takes a long time to seal the end portion, and the manufacturing is not easy.

The present invention has been made to solve the above problems, and an object thereof is to obtain a fluorescent lamp which is not easily damaged even if the glass bulb is thin. Another object of the present invention is to obtain a fluorescent lamp which has a small non-light emitting portion at the end and is easy to manufacture.

[0008]

In a fluorescent lamp according to the present invention, 20 to 20 parts of xenon are contained in a transparent dielectric container having a phosphor on the inner wall and one or more pairs of conductors on the outer wall.
A mixed gas of noble gas containing 200 Torr is 400 to 760.
Torr is enclosed.

Further, neon or helium is mixed as a rare gas other than xenon.

Further, after introducing the gas, the introduction part of the dielectric container is heated and melted to be sealed.

[0011]

In the fluorescent lamp constructed as described above, since xenon has the lowest ionization voltage and excitation voltage, only xenon is selectively excited and emits ultraviolet rays, and the voltage is not so different from that of xenon alone. It lights up and almost the same brightness is obtained. Further, since the pressure inside the lamp is close to the pressure outside the lamp, the pressure applied to the dielectric container is small and is not easily damaged.

Since neon and helium have much smaller atomic weights than xenon, they are less affected by collisions with xenon, and even if they are enclosed in a large amount, they hardly affect the voltage and brightness required for discharge.

Further, since the difference from the ambient pressure is small, the deformation of the dielectric container when heated and melted is small.

[0014]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a fluorescent lamp of the present invention, 2 is a straight cylindrical glass bulb made of lead glass, which is a dielectric having a diameter of 6 mm and a thickness of 0.5 mm, which constitutes the fluorescent lamp 1.
A phosphor layer 3 is formed on almost half of the inner wall of the glass bulb, and the remaining half of the glass bulb serves as a light output section 4 for irradiating the light generated inside the lamp to the outside of the lamp. External electrodes 5a and 5b, which are conductors having a width of 5 mm, are provided on the outer wall of the glass bulb 2 with an interelectrode distance of 0.8 mm. A rare gas containing xenon is enclosed in the glass bulb 2.

The operation of the fluorescent lamp device having such a structure will be described. The high frequency lighting circuit is composed of a transistor inverter or the like and generates a high frequency voltage of about 20 to 200 kHz and applies it to the external electrode 5. A discharge is generated between the external electrodes 5a and 5b, and the ultraviolet rays generated at that time excite the phosphor layer 3 and are converted into visible light determined by the phosphor. Visible light generated from the phosphor is the light output unit 4
Is irradiated from.

The characteristics of this discharge will be described in detail below. The voltage is applied to the inside of the lamp through a glass bulb which is a dielectric, that is, by capacitive coupling between the external electrode and the discharge gas. The discharge current is limited by the dielectric and does not evolve from glow discharge to arc discharge. Further, the discharge is not concentrated on a specific place, and the discharge is generated from the entire inner surface of the glass bulb facing the external electrode. The discharge starts when a voltage is applied between the external electrodes and the inside of the lamp becomes a dischargeable electric field. After that, electric charges such as electrons and ions generated by the discharge are accumulated on the surface of the glass bulb, and as a result, the electric field inside the lamp is weakened and the discharge cannot be continued, and the discharge is stopped. Therefore, a large amount of current flows immediately after the polarity of the applied voltage is reversed, and the current becomes almost pulse-shaped. When the discharge state inside the lamp is observed in detail, it can be seen that the entire inner surface of the glass bulb facing the external electrode is covered with a substantially uniform light, and more filamentous discharges are generated between the paired electrodes. Can be seen.

2 and 3, the fluorescent lamp 1 has a xenon 10
The characteristics are shown when a mixed gas of 0% gas and xenon 20% and neon 80% by volume is filled. FIG. 2 shows the relationship between the pressure of xenon, the discharge starting voltage and the minimum sustaining voltage. Here, the minimum sustaining voltage is
It is the lowest voltage for continuing discharge. It can be seen from FIG. 2 that the voltage increases as the pressure of xenon increases. Therefore, it is not preferable to bring the pressure of xenon close to 1 atm because the voltage required for discharge rises. However, it can be seen that the gas with 100% xenon and the gas with 20% xenon have almost the same discharge start voltage and minimum sustaining voltage even if the pressure of xenon is the same, although the total pressure is 5 times different. .

FIG. 3 shows the relationship between the pressure of xenon and the brightness. The higher the xenon pressure, the higher the brightness. However, it is almost saturated at 200 Torr. Further, it can be seen from this figure that a gas containing 100% xenon and a mixed gas containing 20% xenon exhibit almost the same brightness if the pressure of xenon is the same. Such a phenomenon is because the ionization voltage or excitation voltage of neon is considerably higher than that of xenon, so that inelastic collisions involving excitation or ionization almost exclusively occur in xenon.

2 and 3, by using the mixed gas, the total pressure can be greatly increased without raising the voltage required for discharge and without lowering the brightness.
However, if the pressure of xenon is too low, sufficient brightness cannot be obtained, so that a minimum of about 20 Torr is required. Further, when the pressure of xenon is about 200 Torr and the brightness is saturated, a pressure lower than that is preferable. Further, since the pressure of conventional xenon is several tens Torr, there is a pressure difference of about 1 atm inside and outside the lamp. In order to reduce the possibility of breakage due to this pressure difference, it is desirable to make this pressure difference 1/2 or less. Therefore, the total pressure is 400T
It is preferable that it is not less than orrr and not more than 760 Torr.

Example 2. Xenon 20%, krypton, argon, neon, and helium are added to a fluorescent lamp 1 using a glass bulb having a diameter of 3 mm and a thickness of 0.3 mm, respectively.
The gas mixed with 0% was sealed at 500 Torr. Conductor 5
Had a width of 2.5 mm and a spacing of 0.4 mm. The characteristics of these lamps are shown in Table 1.

It can be seen from Table 1 that a mixture of rare gases having a small atomic weight exhibits characteristics closer to those of xenon alone. Especially, it is understood that the mixed gas of neon and helium is less affected by the mixing and is preferable as the mixed gas. It is considered that this is because the rare gas having a smaller atomic weight has a larger difference in ionization voltage and excitation voltage from xenon.

Example 3. FIG. 4 is a diagram showing a process of heating and melting and sealing the end portion of the glass bulb. In FIG. 4A, the glass bulb 2 is closed at one lower end and opened at the upper end. Although not shown, the upper end is connected to the gas cylinder. Xenon gas 30 from the upper end
% Mixed gas of neon and xenon is 500 Torr
After the introduction, the gas burner 10 is locally heated. When the heated portion reaches the softening point of the glass or higher, FIG. 4 (b)
The glass begins to deform like. Further, by pulling the glass bulb downward while heating as shown in FIG. 4C, the heated portion is melted and the end portion is closed.

The glass bulb is deformed in such a manner that the heated portion is indented due to the pressure difference between the inside and the outside of the bulb. When the pressure difference is close to 1 atm, there is a large inward dent, and a portion that does not contribute to light emission occurs. In the case of this embodiment, since the pressure difference between the inside and the outside is small, the deformation speed is slow and the deformation degree is small. Therefore, it is possible to emit light to the very end. In principle, the deformation is smallest when the pressure difference between the inside and the outside is zero. However, by heating the glass bulb, the internal gas is heated and the pressure rises. Therefore, the pressure of the gas to be enclosed needs to be lower than 1 atm. The appropriate filling gas pressure depends on the heating conditions. In this embodiment, a gas burner is used for heating and welding, but if a laser is used, local heating can be performed in a short time, so that a gas of approximately 1 atm can be enclosed.

[0024]

Since the present invention is constructed as described above, it has the following effects.

Since a mixed gas of xenon and another rare gas is used, a high gas pressure can be enclosed without changing the characteristics such as the discharge starting voltage and the brightness, and the damage is less likely to occur.
Manufacturing is easy.

[Brief description of drawings]

FIG. 1 is a perspective view of a fluorescent lamp showing a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the pressure of xenon, the discharge start voltage, and the minimum sustaining voltage, showing the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between pressure and brightness of xenon showing Example 1 of the present invention.

FIG. 4 is a diagram showing a sealing process of a lamp showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a conventional fluorescent lamp.

[Explanation of symbols]

 1 Fluorescent lamp 2 Glass bulb 3 Phosphor layer 5 External electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadayuki Matsumoto 2-14-40 Ofuna, Kamakura City Mitsubishi Electric Corporation Life Systems Research Institute

Claims (4)

[Claims] 1. A fluorescent lamp in which a discharge gas is enclosed inside a transparent dielectric container having a phosphor on the inner wall and a pair of electrodes on the outer wall, and a high frequency voltage is applied to the electrodes. As a fluorescent lamp, a mixed gas of a rare gas containing xenon is used as 400 to 760 torr. 2. The fluorescent lamp according to claim 1, wherein the mixed gas contains neon or helium. 3. The xenon is 20 to 200 Torr.
The fluorescent lamp according to claim 1 or 2, wherein 4. A mixed gas consisting of a rare gas containing xenon is placed inside a transparent dielectric container having a phosphor on its inner wall.
A method of manufacturing a fluorescent lamp, characterized in that the gas introduction part of the dielectric container is heated and melted and sealed after the gas is introduced from 00 to 760 Torr.