JPH04286850A - Low pressure discharge lamp - Google Patents

Abstract

PURPOSE:To provide a low pressure discharge lamp which can prevent the occurrence of electric discharge owing to dummy wells formed in the stem to make the temperature distribution of the stem uniform and prevent the stem and the bulb from being damaged. CONSTITUTION:In a low pressure discharging lamp wherein the end part of a glass bulb 11 is sealed by a flat glass stem 1, wells 6 to be connected with an electrode 31 is penetrated into the stem air-tightly, and dummy wells 8, 9 not to be connected with the electrode are installed, the dummy wells are coated with an insulator not to be exposed to the inside space of the bulb.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure discharge lamp in which the end of the bulb is closed with a flat glass stem such as a button stem.

0002

2. Description of the Related Art Fluorescent lamps in which the end of a glass bulb is closed with a button stem are known. Lamps using button stems can shorten the electrode height, that is, the protruding length of the electrode from the end of the bulb to the tip of the electrode, compared to lamps using flared stems. The effective emission length can be increased compared to when using .

However, when joining the button stem to the open end of the bulb in an airtight manner, the stem, which has passed through the well connected to the electrode in advance, is butted against the open end of the bulb via a fritted glass or the like. is heated to melt the frit glass, which joins the stem to the bulb.

[0004] In this case, since a well connected to an electrode passes through the stem, this well is also heated by the above heating. Moreover, since Wells is made of metal, it has excellent thermal conductivity and its temperature rises more easily than glass. For this reason, the stem temperature rises at the point where the wells penetrate,
Temperatures do not rise that much in areas far away from here. Therefore, when the number of wells is small, a temperature difference occurs in the stem, causing distortion. Such distortion occurs not only in the sealing process but also in the usage process of repeatedly turning on and off, and causes cracks and leaks in the stem.

[0005] In order to prevent such problems,
Japanese Patent No. 144558 proposes a method in which a dummy well is inserted through the button stem in addition to the well connected to the electrode.

[0006] In this case, even if the well connected to the electrode is heated during the sealing process or during lighting use, the dummy well is also heated at the same time. There is an advantage that temperature rise is prevented and distortion can be prevented from occurring.

[0007]

However, in the conventional case where dummy wells are used as described above, these dummy wells penetrate the stem and have their inner ends exposed to the discharge space. If the inner ends of the dummy wells are exposed to the discharge space, the electrode material evaporated by the discharge and the electron emitting material (emitter) coated on the electrodes will scatter and adhere to these dummy wells, reducing the lifespan of the lamp. As the final stage approaches, arc spots may occur in these dummy wells without regular discharge from the electrodes, and discharge may occur in the dummy wells. In the case of such abnormal discharge, problems such as cracks in the stem and bulb and heavy burden on the lighting circuit occur.

The present invention was made based on the above circumstances, and its object is to provide a low-pressure discharge lamp that can prevent discharge from occurring in the dummy wells and prevent damage to the stem and bulb. This is what we are trying to provide.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized in that the dummy wells are insulated so as not to be exposed to the discharge space.

0010

According to the present invention, since the dummy well is insulated so as not to be exposed to the discharge space, discharge is prevented from occurring in the dummy well, and damage to the stem and bulb can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on an embodiment shown in FIGS. 1 to 4.

The drawings show the case of a meander-shaped compact fluorescent lamp, and the overall structure will be explained with reference to FIGS. 3 and 4. In the fluorescent lamp, a plurality of, for example, two U-shaped glass bulbs 11 and 12 are connected through an insulating base 13 made of ceramic or the like to form one discharge space.

Each bulb 11, 12 is U-shaped and has a phosphor coating 14, 15 formed on its inner surface. Each of the bulbs 11 and 12 has a circular cross section at its end, but has a flattened shape with an oval cross section over a predetermined region including a bent portion.

[0014] The portion L having a flat cross section has a length of 1/3 or more of the length from the bent portion to the opening end, in other words, 1/3 or more of the length of the straight portion. Also,
In the portion where the cross section is flat, it is desirable that the flattening ratio expressed by major axis/minor axis is 2.0 or more.

The bulbs 11 and 12 are arranged such that their U-shaped planes face each other, and are connected via the insulating base 13. Note that FIG. 3 is an expanded view.

A communication recess 16 having an oval shape and a closed bottom is formed on the upper surface of the insulating base 13, and small-diameter through holes 17 and 18 are formed at a distance from the communication recess 16. is formed.

The communication recess 16 opened on the upper surface of the insulating base 13 is closed by an upper cover 20. As shown in FIG. Upper lid 20
is made of a translucent material such as glass, and is hermetically joined to the opening of the communicating recess 16 with frit glass or the like. The upper lid 20 has a cylindrical connection port 2.
1 and 22 are formed protrudingly, and these connection ports 21,
One end of each of the bulbs 11 and 12 is fitted into the connector 22, and the one end of each of the bulbs 11 and 12 is hermetically joined to the connection ports 21 and 22 by frit glass.

For this reason, the two U-shaped valves 11,
12 communicate with each other through a communication recess 16 formed in the insulating base 13, so that the entire discharge space is meandering like a saddle shape.

Incidentally, phosphor coatings 23 and 24 are formed on the inner surface of the communication recess 16 and the inner surface of the upper lid 20 made of a translucent material, respectively. It converts ultraviolet rays into visible light and emits it to the outside. The other ends of the bulbs 11 and 12 are joined to small diameter through holes 17 and 18 of the insulating base 13 via frit glass.

In this case, electrodes 31 and 32 are sealed at the other ends of the bulbs 11 and 12, respectively. Electrode 3
1 and 32 are attached to button stems 1 and 2, respectively, and these button stems 1 and 2 are hermetically joined to the other end of each bulb 11 and 12 via a frit glass. The structure of a mount in which the electrodes 31 and 32 are attached to the stems 1 and 2 will be explained with reference to FIGS. 1 and 2 for one mount.

The button stem 1 is made of disk-shaped glass, has an annular groove 3 around its upper surface, and has an exhaust hole 4 opened in the center. An exhaust pipe 5 extending from the bottom surface of the button stem 1 is connected to the exhaust hole 4. In addition,
The stem 2 of the other mount is not provided with the exhaust hole 4 and the exhaust pipe 5.

[0022] The button stem 1 has a pair of wells 6 and 7.
is penetrated airtight. These pair of Wells 6 and 7
is made of conductive metal wire, such as nickel or its alloys,
They are arranged symmetrically with respect to the center of the stem 1, and an electrode 31 is spanned between these inner ends. Electrode 3
1 is a tungsten filament, that is, a hot cathode,
Although not shown, it holds an emitter.

The button stem 1 has the wells 6
, 7, dummy wells 8 and 9 are attached. The dummy wells 7 and 8 are also made of conductive metal wires, such as nickel or its alloy, in the same way as the wells 6 and 7 connected to the electrode 31, and are spaced evenly in the circumferential direction together with the wells 6 and 7 connected to the electrode 31. They are placed at intervals.

In this embodiment, the inner ends of the dummy wells 8 and 9 are not exposed on the upper surface side of the button stem 1, but are embedded in the button stem 1. In other words, dummy wells 8,
9 is designed not to be exposed to the discharge space. The mount having such a structure is sealed at the end of the bulb 1 by joining the button stem 1 to the end of the bulb 11 via a frit glass.

As described above, the ends of the valves 11 and 12 are connected to the small diameter through holes 17 and 1 of the insulating base 13.
8 through a frit glass. and,
Each well 6, 7 and exhaust pipe 5 have these through holes 17,
18 and is led to the lower surface side of the insulating base 13. Note that a predetermined amount of mercury and a rare gas consisting of argon are sealed in the discharge space in which the bulbs 11 and 12 are communicated. The operation of the fluorescent lamp having such a configuration will be explained.

Electrodes 31 and 32 located at both ends of the discharge space
When a voltage is applied between them, the communication recess 16 of the insulating base 13
A discharge is generated inside each of the bulbs 11 and 12 that are in communication via the mercury atoms, and mercury atoms are excited within the meandering discharge space.
emits ultraviolet light. This ultraviolet light is converted into visible light by the phosphor coatings 14, 15 formed on the inner surfaces of the bulbs 11, 12 and the phosphor coatings 23, 24 formed on the inner surfaces of the communication recess 16 and the upper cover 20, and released outside.

In this case, the communication recess 16 of the insulating base 13
The phosphor coatings 23, 2 are also provided on the inner surface of the
4, the ability to convert ultraviolet rays into visible light is improved and the amount of light emitted can be increased.

Further, the valves 11 and 12 of the above embodiment are as follows:
Since the cross section of the part that effectively contributes to light emission is made into a flat shape, the brightness of the surface is improved, and the area L of this flat shape is made to be at least 1/3 of the length from the bent part to the opening end, in other words. Since the length is 1/3 or more of the length of the straight portion, the illuminance directly below is improved when the light is turned on with the orientation shown in FIG. 3 upside down.

Since the electrodes 31 and 32 provided at the ends of the bulbs 11 and 12 are supported by the button stems 1 and 2, the height of the electrodes can be lowered and the effective length of light emission can be increased. be able to.

Furthermore, when joining the stems 1 and 2 to the bulbs 11 and 12, the frit glass interposed between them is heated and melted to achieve an airtight joint with this molten glass. For heating the glass, the wells 6 connected to the electrodes 31 and 32,
Since the wells 6 and 7 are penetrated, the above heating causes the wells 6 and
7 is also heated. At this time, the dummy wells 8 and 9 are also heated in the same way. Since the wells 6 and 7 and the dummy wells 8 and 9 are arranged at equal intervals in the circumferential direction of the stem 1, the temperature rise in the stem 1 is more evenly distributed throughout than in the case where the dummy wells 8 and 9 are not provided. Ru. Further, the temperature of the stem 1 rises even in the course of use when the light is repeatedly turned on and off, and the temperature distribution becomes even in this case as well. As a result, the occurrence of distortion in the stem 1, the valve 11, and between them is reduced, and the occurrence of cracks and leaks can be reduced.

The ends of the dummy wells 8 and 9 are embedded in the stem 1, that is, the dummy wells 8 and 9 are embedded in the stem 1.
9 is covered with the glass of the stem 1 so that it is not exposed to the discharge space. This prevents the evaporated electrode material and the emitter coated on the electrode from scattering and adhering to the surfaces of these dummy wells 8 and 9. Therefore, the generation of arc spots on the dummy wells 8 and 9 is prevented, and the generation of electric discharge on the dummy wells 8 and 9 is eliminated. This eliminates problems such as cracks in the stem or bulb and heavy burden on the lighting circuit.

In the case of the above embodiment, the ends of the dummy wells 8 and 9 were embedded in the stem 1 and insulated by stem glass, but the present invention is as shown in another embodiment shown in FIG. The ends of the dummy wells 41 and 42 may be passed through the stem 1, and the ends of the dummy wells 41 and 42 exposed to the discharge space may be covered with insulating coatings 43 and 44. In addition, stems are not limited to button stems,
Any stem having a flat shape may be used.

[0033] In the above embodiments, the case of a hot cathode fluorescent lamp was explained, but the present invention may be a cold cathode fluorescent lamp or a rare gas discharge lamp that does not use mercury. Good too. Furthermore, the number of dummy wells used is not limited to two, but may be one or three or more.

[0034]

[Effects of the Invention] As explained above, according to the present invention, since the dummy well is insulated so as not to be exposed to the discharge space, generation of discharge in the dummy well is prevented.
Damage to the stem and valve can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a mount showing an embodiment of the present invention.

FIG. 2 is a sectional view of the same embodiment.

FIG. 3 is a partially sectional side view showing a developed fluorescent lamp using the mount.

FIG. 4 is an exploded perspective view of the same embodiment.

FIG. 5 is a sectional view of a mount showing another embodiment of the present invention.

[Explanation of symbols]

11, 12... Bulb, 1, 2... Stem, 6, 7... Wells, 8, 9... Dummy wells, 31... Electrode, 41, 42
...Dummy wells, 43, 44...Insulating coating.

Claims (1)

[Claims] Claim 1. A low-pressure discharge lamp in which the end of the glass bulb is closed with a flat glass stem, and the stem is provided with a dummy well that airtightly passes through a well connected to an electrode and is not connected to the electrode. Dummy Wells is a low-pressure discharge lamp characterized by covering the inner space of the bulb with an insulating material.