JP3208329B2 - Flat fluorescent lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat fluorescent lamp used for a backlight of a liquid crystal viewfinder of a video camera and a backlight of a liquid crystal display.

[0002]

2. Description of the Related Art As shown in FIG.
The upper surface is covered with a rectangular windshield (1) to form a discharge chamber, and a flat glass box (2) in which an inert gas such as argon gas is sealed is provided with a pair of elongated electrode pieces (4). (5)
Are provided in parallel with each other (see FIG. 8). Both electrode pieces (4)
(5) is provided close to the windshield (1), sandwiched between frit glasses (20), (20), and attached to the glass box (2). Glass box (2) inner surface and windshield
The inner surface of (1) is covered with a layer of the phosphor (7), and the phosphor (7) emits light by discharge between the two electrode pieces (4) and (5),
Illuminate the front of the windshield (1).

[0003] In a dark state where light does not enter from the surroundings,
It is known that since an inert gas is not ionized in an ion state, it is difficult for discharge to occur and for lighting to be difficult. Therefore,
To facilitate starting from the dark state, the applicant has already proposed the following (see Japanese Patent Application No. 7-309426, the invention has not been disclosed). As shown in FIG. 7, a metal conductive film (9) that allows electron flow is formed on the periphery of the upper surface of the windshield (1). A negative voltage is applied to one electrode piece (4) and the other electrode piece (5)
Is grounded. Electrode piece (4) and conductor coating (9)
When starting lighting, first, the electrode piece (4)
And discharge between the conductive film (9). The degree of ionization of the inert gas located between the electrode piece (4) and the conductor coating (9) increases, and discharge occurs even between the earthed electrode piece (5) and the conductor coating (9). Begin. Once the discharge is thus induced, the electrons from the electrode piece (4) gradually ionize the inert gas in the discharge chamber, and the direct discharge at both electrode pieces (4) and (5) becomes a steady state. Become.

[0004]

In order to mass produce windshields (1), a large number of windshields (1) are arranged in a plane as shown in FIG. Mask (6) as shown by the dashed line at the center
In general, a conductive film 9 is formed by sputtering or the like at an exposed portion covered by (6a) and not covered by the masks 6 and 6a. However, in such a forming method, if the central portion of each windshield (1) is masked, the mask (6a) corresponding to each central portion is replaced with a mask (6) covering the peripheral portion of the windshield (1). Separately provided and must be kept in place, which is very difficult and time-consuming. Therefore, it is not suitable for mass production to form the conductor coating 9 over the peripheral portion of the windshield 1. Many windshields with one mask pattern
To cover (1) and form a conductive film by sputtering or the like, and to smoothly carry out mass production of the windshield (1), the mask pattern should cover only the periphery of the windshield (1) and cover the conductive film. The shape must cover almost the entire surface of the windshield (1) except the peripheral portion. However, if the entire surface of the windshield (1) is covered with a conventional metal conductive film, light transmittance is poor. In this case, ITO (Indium Tin Oxide) having excellent visible light transmittance is used.
It is necessary to use a transparent conductive film such as a film. Further, in the conventional fluorescent lamp, the electrode piece (5) connected to the ground and the conductor coating are used.
(9) is close but not electrically connected directly, so that the electrons from the electrode piece (4) can reach the electrode piece (5) in order to reach the electrode piece (5) with the conductor coating (9). ) And the electric discharge must be performed twice between the conductor coating 9 and the electrode piece 5, so that the operation is unstable.

In a discharge at a low temperature of about -20.degree. C., electrons flow along the periphery of the glass box (2),
As a result, it is empirically known that the center of the windshield (1) becomes dark. Therefore, in order to make the entire surface of the windshield (1) emit light with uniform brightness at a low temperature, it is necessary to bring the electron flow to the center of the windshield (1). The applicant has conceived of forming a conductive film by a transparent conductive film, and using the transparent conductive film to bring the electron flow in the glass box (2) to the center of the windshield (1). . SUMMARY OF THE INVENTION It is an object of the present invention to make uniform light emission over the entire surface of a windshield at a low temperature.

[0006]

The flat fluorescent lamp according to the first aspect of the present invention has a glass box (2) having a windshield (1) on the upper surface, in which an inert gas is sealed, and a pair of fluorescent lamps is provided. Discharge electrode pieces (4) and (5) are provided facing each other, and the windshield
A layer of phosphor (7) is formed on the inner surface of (1), and a conductor film is formed on the outer surface. The conductor film is a transparent conductive film
(3), which is disposed near the two electrode pieces (4) and (5) on the outer surface of the windshield (1) and in the center between the two electrode pieces (4) and (5); Cutouts (30) and (30) without the transparent conductive film (3) are formed on both sides of the outer edge between (5) and (5), so that the electron flow along the transparent conductive film (3) can be centered on the windshield (1). To the department. In the flat fluorescent lamp according to the second aspect of the present invention, in addition to the above, one electrode piece (5) and the transparent conductive film (3) are electrically connected to each other and kept at the same potential, and the electrode piece ( 5) is grounded.

[0007]

In the flat fluorescent lamp according to the first aspect of the present invention, since the transparent conductive film (3) covers the central portion of the windshield (1), workability when forming by sputtering or the like is improved. It becomes easier and mass production of the windshield (1) becomes easier. Notches are provided on both sides of the transparent conductive film (3).
Since (30) and (30) are opened and the electrons do not pass through the cutouts (30) and (30), the electron flow approaches the center of the transparent conductive film (3).
Therefore, even at a low temperature where the electron flow at the time of discharge tends to approach the side of the windshield (1), the electron flow can be forcibly brought to the center, and the light emission over the entire surface of the windshield (1) is uniform. Can be In the flat fluorescent lamp according to the second aspect of the present invention, the transparent conductive film (3) and the electrode piece (5) are provided.
Are electrically connected, the potential difference between the electrode piece (5) and the transparent conductive film (3) is equal. That is, in order for electrons emitted from the electrode piece (4) to reach the electrode piece (5), the transparent conductive film (3)
It suffices that one discharge is performed between the electrode and the electrode piece (4),
Electron flow operation is stabilized. Therefore, even if the inert gas is in a dark state that is not in an ionized state, the fluorescent lamp is quickly discharged to a steady state.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below with reference to the drawings. The same components as those of the related art will be described using the same reference numerals. As shown in Figure 1, the top is the windshield
An inert gas such as argon gas is sealed in the glass box (2) covered by (1) as in the prior art, and the inner surfaces of the windshield (1) and the glass box (2) are as follows. Phosphor (7)
Layer. In the glass box (2), a pair of electrode pieces (4) and (5) are arranged in parallel to each other, and as shown in FIG. 2, the electrode pieces (4) and (20) are made of frit glass (20) and (20). 5) is attached to the glass box (2). As shown by hatching in FIG. 1, a transparent conductive film (3) having excellent visible light transmittance is formed on the upper surface of the rectangular windshield (1).
In the central region between (4) and (5), cutouts (30) and (30) are formed on both sides of the transparent conductive film (3) toward the central portion. As the transparent conductive film (3), an ITO film formed by adding a trace amount of tin to indium oxide is desirable. One electrode piece
(5) is grounded, and the electrode piece (5) and the windshield
The transparent conductive film (3) on (1) is electrically connected to the transparent conductive film (3) by a layer of a conductive paste (8) in which silver filler is mixed in a conductive resin. A negative voltage is applied to the other electrode piece (4), and the electrode piece (5) is on the higher voltage side than the electrode piece (4) (see FIG. 6).

As shown by a two-dot chain line in FIG. 4, the transparent conductive film (3) is formed by arranging a large number of windshields (1) on the same plane, performing a masking process from above, and performing sputtering or the like. The mask for masking treatment (6) is integrally provided with a connecting piece (60) for covering the peripheral portion of the windshield (1) and a shielding piece (61) corresponding to the notch (30). The transparent conductive film (3) can be formed on the windshield (1) at a time. Actually, the width of the connecting piece (60) is very short compared to the length and width of the windshield (1), and after forming the transparent conductive film (3), the width of the periphery of the windshield (1) is reduced. The portion where the transparent conductive film (3) is not formed does not stand out.

(At the start of discharge) In a dark state where the surroundings are dark, the inert gas in the glass box (2) is not ionized, and
It is difficult for the electrons scattered from (4) to pass through the inert gas and directly reach the electrode piece (5). In the fluorescent lamp according to this example, in order to perform the lighting operation smoothly,
Take the following steps. As shown in FIG. 6, the electrode piece (5) and the transparent conductive film (3), which are connected to the ground, are connected by the conductive paste (8). It is the same potential. Initially, when a negative voltage -HV is applied to the electrode piece (4), the potential difference between the electrode piece (4) and the transparent conductive film (3) increases, and the potential difference between the electrode piece (4) and the transparent conductive film (3) increases. Discharge occurs between the two. The electrons e flow along the transparent conductive film (3) which causes a potential difference with the electrode piece (4), and reach the other electrode piece (5).

As described above, when the discharge starts, the electrons flow along the transparent conductive film (3), so that even in the dark, the electrons flow to the electrode piece (5) connected to the ground. Induced by the discharge and the electron flow, the inert gas is ionized, and FIG.
As shown by a two-dot chain line, the discharge between the electrode pieces (4) and (5) reaches a steady state. The layer of the phosphor (7) provided on the back surface of the windshield (1) and on the inner surface of the glass box (2) emits light, and the light passes through the transparent conductive film (3) and is applied to the front glass (1). Illuminate the front. Such fluorescent lamps are often used by being embedded in a liquid crystal viewfinder, so that the surroundings of the fluorescent lamp are dark when not in use. Therefore, the usability of the liquid crystal viewfinder is improved by improving the lighting properties in darkness.

The transparent conductive film (3) is composed of both electrode pieces (4) and (5).
Since the notches (30) and (30) are provided on both sides between them, the electrons flowing along the transparent conductive film (3) are not cut off (30) and (30).
Without passing through, it is forcibly brought to the center of the transparent conductive film (3). As a result, the electron flow during discharge is
It flows through the inert gas along the center of (1). In the fluorescent lamp according to this example, after the discharge starts, the transparent conductive film
The electrons easily flow along the center of the windshield (1) along (3), so that the center of the windshield (1) emits light strongly and the light emission over the entire surface of the windshield at low temperatures is uniform. can do. In addition, such a notch (30)
Even if (30) is installed, at room temperature, the windshield (1)
It has been confirmed by the applicant that the sides of the. Further, in the flat fluorescent lamp, the transparent conductive film (3) and the electrode piece (5) are connected by the conductive paste (8). Even if they are electrically separated, if the notches (30) and (30) are formed, the effect of bringing the electron flow to the center of the transparent conductive film (3) can be obtained.

In FIG. 1, the transparent conductive film (3) and the electrode piece (5) are connected by a conductive paste (8). FIG. This is because the electrode piece (5) and the transparent conductive film (3) are not connected by the conductive paste (8), but are instead placed on the transparent conductive film (3) facing the electrode piece (4) to which a negative voltage is applied. A metal foil (80) made of copper or aluminum is adhered, and one end of the metal foil (80) is connected to a ground point of a circuit board (81) to which the glass box (2) is attached. Also in this configuration, since the transparent conductive film (3) has the same potential as the electrode piece (5), the electrode piece (4) to which a negative voltage is applied and the transparent conductive film are used.
Discharge occurs between (3) and (3), and electrons flow along the transparent conductive film (3) and reach the other electrode piece (5). As described above, the discharge and the electron flow induce the inert gas to be ionized, and the discharge between the electrode pieces (4) and (5) reaches a steady state. Further, in the above example, the notches (30) and (30) are formed in a rectangular shape, but may be in an arc shape, for example, as shown by a dotted line in FIG. Further, in the above example, a negative voltage is applied to the electrode piece (4), but a positive voltage may be applied. In this case, the electron flow is reversed from the above example.

The description of the above embodiments is for the purpose of illustrating the present invention and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view of a flat fluorescent lamp.

FIG. 2 is a sectional view of FIG. 1 taken along line AA.

FIG. 3 is a front view of a flat fluorescent lamp illustrating an electron flow.

FIG. 4 is a plan view showing a state in which a large number of windshields are arranged and masking is performed.

FIG. 5 is a perspective view of a flat fluorescent lamp according to another embodiment.

FIG. 6 is a diagram showing an electron flow in a discharge initial state.

FIG. 7 is a perspective view of a conventional flat fluorescent lamp.

FIG. 8 is a perspective view of an electrode piece.

FIG. 9 is a cross-sectional view of FIG. 7 taken along line BB.

FIG. 10 is a plan view showing a mask pattern when a central portion of a windshield of a conventional flat fluorescent lamp is masked.

[Explanation of symbols]

 (1) Windshield (2) Glass box (3) Transparent conductive film (4) Electrode piece (5) Electrode piece (7) Phosphor (8) Conductive paste (30) Notch (80) Metal foil

Claims (3)

(57) [Claims] An inert gas is sealed in a glass box (2) having a windshield (1) on an upper surface, and a pair of discharge electrode pieces (4) and (5) are provided to face each other.
(1) In a flat fluorescent lamp in which a layer of a phosphor (7) is formed on the inner surface and a conductor film is formed on the outer surface, the conductor film is a transparent conductive film (3). , Disposed on the outer surface of the windshield (1) in the vicinity of the two electrode pieces (4) and (5) and in the central region between the two electrode pieces (4) and (5).
(5) Notch without transparent conductive film (3) on both sides of outer edge between
(30) A flat fluorescent lamp, wherein (30) is formed, and the electron flow along the transparent conductive film (3) is brought to the center of the windshield (1). 2. A plane according to claim 1, wherein one of the electrode pieces (5) and the transparent conductive film (3) are electrically connected and kept at the same potential, and the electrode piece (5) is grounded. Type fluorescent lamp. 3. One of the electrode pieces (5) is grounded to electrically separate the electrode piece (5) from the transparent conductive film (3) and to form a metal foil (80) on the transparent conductive film (3). ), And the metal foil (80) is attached to the circuit board (81) to which the glass box (2) is attached.
The flat fluorescent lamp according to claim 1, wherein the flat fluorescent lamp is connected to a grounding point.