JPH0495337A - Flat fluorescent lamp - Google Patents

Abstract

PURPOSE:To shorten the space required for installing electrodes within a discharge space and uniform discharge between the electrodes and also reduce the width of a non light-emitting portion by forming an electrode serving as an anode which is in the form of a flat plate or bar. CONSTITUTION:In a flat fluorescent lamp having a flat discharge space formed between a front glass plate and a back glass plate therein and a pair of electrodes arranged in parallel within the discharge space, one electrode 6 is formed into the shape of a flat plate and disposed within a plane perpendicular to a glass plate 2 and the other electrode 5 is formed into a hollow cathode type electrode of a surface area larger than that of a strip electrode 6 by bending or curving of a bar-shaped or strip body along its longitudinal direction and the hollow cathode type electrode 5 is used as a cathode and the other flat electrode 6 as an anode. A pulse of negative voltage is applied to the cathode and zero potential is constantly applied to the anode, or, zero potential is constantly applied to the cathode and a pulse of positive voltage is applied to the anode so as to generate flat discharge and this intermittent voltage application is continued so as to maintain the flat discharge. Then the amount of electrons emitted is uniformed in the longitudinal direction of the electrode 5 and discharge of high emission efficiency can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flat fluorescent lamp used as a backlight for a viewfinder of a video camera or a liquid crystal display device such as a liquid crystal television.

(Prior Art) A liquid crystal display device requires a backlight that illuminates a liquid crystal display panel from behind, and this backlight is required to illuminate the entire liquid crystal display panel with uniform brightness.

The applicant previously proposed a flat fluorescent lamp shown in Fig. 4 in order to realize a flat light source (Japanese Patent Application Laid-Open No. 18915/1983).
No. 4).

The above-mentioned flat fluorescent lamp is a flat container made by airtightly joining a front glass plate (2) and a rear glass plate (3) with a frame (4) in between, the inner surfaces of which are coated with phosphors (21) and (31). (1) is formed.

The inside of the container (1) serves as a discharge space, and is filled with argon gas and mercury vapor.

Inside the container, a pair of electrodes (5) (5) are arranged facing each other, and lead pieces (51, (5)) connected to each electrode are exposed to the outside of the container.

By applying an alternating voltage to the electrode, the electrode (5) (
5) A discharge occurs between them, and the argon gas and mercury emit ultraviolet light. This ultraviolet light excites the phosphor and emits visible light.

In order to achieve high luminous efficiency and uniform planar discharge, it is necessary to increase the amount of electron emission, and for this reason, it is desirable that the electrode (5) be of a so-called hollow cathode type with a large area.

Further, since both electrodes are alternately switched to a cathode and an anode by application of an alternating current voltage, it is desirable that the electrodes be formed in the same shape.

Therefore, both electrodes (5) (5) have upper and lower longitudinal edges bent at right angles to form a U-shaped cross section.

(Problems to be Solved by the Invention) In order to miniaturize video cameras, there is a demand for compact liquid crystal viewfinders that are reduced to 1 inch or less.

However, even for a 1-inch flat fluorescent lamp, the width W of the electrode (5) needs to be approximately 3 mm, and the width of the non-light-emitting part of the flat fluorescent lamp must be adjusted to correspond to the width of the electrode. W2 becomes large and may interfere with viewfinder installation.

Incidentally, a flat fluorescent lamp has also been proposed in which a pair of strip electrodes are disposed facing each other in a flat glass container, but since the area of the electrodes cannot be increased in this lamp, there is a problem that discharge is not uniform between the electrodes.

The present invention discloses a flat fluorescent lamp in which discharge occurs uniformly between electrodes, and the width of the non-emission area can be reduced.

(Means for Solving the Problems) The flat fluorescent lamp of the present invention has a flat discharge space formed between a front glass plate and a rear glass plate, and a pair of electrodes arranged in parallel in the discharge space. In the lamp, one electrode (6) is formed into a flat plate and placed in a plane perpendicular to the glass plate (2), and the other electrode (5) is formed by bending or bending the strip along the longitudinal direction. It is curved to form a hollow cathode type electrode having a larger surface area than the strip electrode (6), the hollow cathode type electrode (5) is used as a cathode, and the other flat electrode (6) is used as an anode.

As the electrode serving as the anode, a rod-shaped electrode may be provided instead of the flat plate electrode.

(Operation) A pulse of negative voltage is always applied to the cathode and zero potential is applied to the anode, or a pulse of zero potential is always applied to the cathode and a pulse of positive voltage is applied to the anode.

Since the maintenance time of a planar discharge is about 50 μsec or less, the discharge is stopped before the planar discharge collapses and enters an arc-like concentrated state, and the maintenance time is approximately 50 μsec or less.
After that, a pulse is applied again to generate a planar discharge, and this intermittent voltage application is continued to maintain the planar discharge.

(Effect) The hollow cathode type electrode (5) serving as the cathode is formed by bending or curving a strip in the longitudinal direction, and the cross-sectional shape perpendicular to the longitudinal direction of the electrode is the same at both locations. The amount of electron emission is made uniform in the longitudinal direction of the electrode (5), and furthermore, since the surface area of the hollow cathode type electrode is large,
Large amount of electron emission. Therefore, a planar, uniform discharge with high luminous efficiency can be expected.

(Effects) Since the electrode that serves as the anode is formed into a flat plate or rod shape, the installation space for the electrode within the discharge space is shortened.
Correspondingly, the width of the non-emission part on the anode side can be made smaller.

(Example) Flat fluorescent lamps each have phosphors (21) (31) on their inner surfaces.
The front glass plate (2) and the back glass plate (3) coated with the above are airtightly joined with frit glass or the like with a glass frame (4) serving as a spacer in between to form a rectangular flat container (1). do.

The inside of the container is evacuated and filled with argon gas and mercury vapor through an exhaust pipe (7) protruding from a part of the frame (4).

A pair of electrodes (5) and (6) are arranged facing each other in parallel on both sides of the discharge space in the container, and a lead piece (51) (
61) allows the container to pass through the side wall in an airtight manner and exit to the outside.

The electrodes (5) and (6) are made of, for example, an iron-nickel alloy, and one electrode (6) is formed into a flat plate shape and arranged in a plane perpendicular to the front glass plate (2).

The other electrode (5) is formed by bending the upper and lower longitudinal edges of a wide strip at right angles in the same direction to form a so-called hollow cathode electrode with a large surface area and a U-shaped cross section, with the opening facing the opposite electrode ( 6).

A drive circuit (8) is connected to the lead pieces (51) and (61) so that the hollow cathode electrode (5) serves as a cathode and the flat electrode (6) serves as an anode. The drive circuit (8) applies a negative pulse voltage to the hollow cathode electrode (5) and a strip electrode (6).
), or apply a zero voltage to the hollow cathode electrode (5).
Any configuration may be used as long as a zero potential can be applied to the strip electrode (6) and a positive pulse voltage can be applied to the strip electrode (6).

Since the duration of a planar discharge is approximately 50 μsec or less, the discharge is stopped before the planar discharge collapses and enters an arc-like concentrated state, and the duration is several tens of μsec to several 100 μsec.
After c, a pulse is applied again to generate a planar discharge, and this intermittent voltage application is continued to maintain the planar discharge.

The applied voltage is preferably 500 to 100 OV, and the pulse width is preferably approximately 50 μSeC or less for the reasons mentioned above.

The hollow cathode electrode (5), which serves as a cathode, is formed by bending or curving a strip in the longitudinal direction, and the cross-sectional shape perpendicular to the longitudinal direction of the electrode is the same at any location. ) The amount of electron emission is made uniform in the longitudinal direction, and furthermore, since the surface area of the hollow cathode type electrode is large,
Large amount of electron emission. Therefore, a planar, uniform discharge with high luminous efficiency can be expected.

As mentioned above, since the electrode (6) serving as the anode is formed into a plate shape and placed close to the side surface of the container, the width w3 of the non-emission part on the anode side is smaller than the width W2 of the non-emission part on the cathode side. Therefore, the length of the flat fluorescent lamp in the inter-electrode direction can be reduced accordingly.

FIG. 3 shows another embodiment of the electrode, in which the electrode (5
0) is an electrode (60) that is formed into a hollow cathode type with a V-shaped cross section by bending the center part of a wide strip plate, and serves as an anode.
is formed into a rod shape.

In this case as well, the same effect as described above is achieved.

The shape of the electrode serving as the cathode is not limited to the above-mentioned U-shaped cross section or V-shaped cross section, but may be any shape that is uniform in the longitudinal direction, such as a U-shaped cross section or an L-shaped cross section. Of course, it can be implemented in various shapes.

Furthermore, a plurality of protrusions (not shown) are provided on the inner surface of the rear glass plate (3), perpendicular to the electrode (5) and reaching the front glass plate (2).
The present invention is not limited to the structure of the above embodiment, and can be modified in various ways within the scope of the claims. It is possible.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view of a flat fluorescent lamp, Figure 2 is a sectional view of a flat fluorescent lamp, Figure 3 is a sectional view of another embodiment, and Figure 4 is a diagram of a conventional flat fluorescent lamp. FIG. (2)...Front glass plate (3)...Back glass plate (5)...Hollow cup-F type electrode

Claims (1)

[Scope of Claims] [1] In a flat fluorescent lamp in which a flat discharge space is formed between a front glass plate and a rear glass plate, and a pair of electrodes are arranged in parallel in the discharge space, one The electrode (6) is formed into a flat plate and is arranged in a plane perpendicular to the glass plate (2), and the other electrode (5) is formed by bending or curving a strip along the longitudinal direction. 6) A flat fluorescent lamp having a hollow cathode type electrode having a larger surface area than that of 6), using the hollow cathode type electrode (5) as a cathode and the other flat electrode (6) as an anode. [2] In a flat fluorescent lamp in which a flat discharge space is formed between a front glass plate and a rear glass plate, and a pair of electrodes are arranged in parallel in the discharge space, one electrode (60) is a rod. The other electrode (50) is formed into a hollow cathode type electrode by bending or curving the strip body along the longitudinal direction, and the hollow cathode type electrode (50) is used as a cathode and the other rod-shaped electrode (6
A flat fluorescent lamp with 0) as the anode.