JPH0713164Y2 - Flat fluorescent lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a flat fluorescent lamp that emits surface light, and more particularly to a fluorescent lamp that is preferably used as a backlight for liquid crystal televisions, liquid crystal displays, and the like.

[Prior Art] Conventionally, as a flat panel fluorescent lamp used for a backlight of various liquid crystal display devices, a pair of glass substrates each having a phosphor film on one surface thereof are arranged substantially parallel to each other, and
The phosphor film is arranged so as to be located inside, and a sealed space is formed by joining at a peripheral portion with or without a spacer, and a pair of cold cathode type is provided on both sides of the sealed space. It is known that electrodes are arranged opposite to each other and a gas containing a small amount of mercury vapor is enclosed in the sealed space. Then, a voltage is applied between the electrodes to discharge the mercury vapor, and the generated ultraviolet rays excite the phosphor film to emit light.

Here, the electrodes are, for example, JP-A-60-225347 and JP-A-63-1169.
As disclosed in 63, nickel or iron alloy is used as the electrode material, and the shape of the electrode is a so-called hollow cathode type electrode having a U-shaped cross section or a depression like a Σ type. Is used.

[Problems to be Solved by the Invention] However, in the above-mentioned cold cathode type discharge tube, a potential gradient necessary for electrons to fly out from the cathode is required on the surface of the cathode during discharge, and this potential gradient (cathode fall) is required. Does not contribute to light emission and causes energy loss.
It is preferable that the cathode drop is small in order to improve the luminous efficiency of a discharge tube such as a fluorescent lamp. The cathode drop that occurs near the cathode surface is determined by the material of the electrode, the shape of the electrode, the surface area of the electrode, and the like. The conventional technique in which the surface of the electrode is a metal such as nickel or iron alloy has the drawbacks that the cathode drop is large and the energy loss is large. The present invention solves the above-mentioned drawbacks and provides a fluorescent lamp with high luminous efficiency.

[Means for Solving the Problems] In the present invention, which improves the above-mentioned drawbacks, the first and second glass substrates, which are arranged substantially parallel to each other and have a phosphor film on the inner surface thereof, are sealed at their peripheries. A fluorescent lamp in which a sealed space containing mercury vapor is formed, and a pair of cold cathode electrodes are arranged to face each other in the sealed space, and a flat type fluorescent lamp in which the surface of the electrodes is coated with lanthanum boride (LaB ₆ ). It is a light.

As a method for coating the surface of the electrode with lanthanum boride, fine powder of lanthanum boride is suspended in, for example, a vehicle liquid (Tanaka Matsusei Co., Ltd. trade name TRB1), and the viscosity is adjusted with ethyl cellulose or nitrocellulose if necessary. To prepare a coating solution. Then, a method is used in which the electrode to be coated with lanthanum boride is dipped in this coating solution, then taken out and dried. Further, a vapor deposition method of coating lanthanum boride in a reduced pressure atmosphere by, for example, an electron beam vapor deposition method can be used.

As shown in FIGS. 3 (a) and 3 (b), the lanthanum boride coating 2B can cover all or part of the surface of the electrode 2A, and has a thickness of several 100 A to several μm. It is preferably used.

[Operation] Since the electrode surface according to the present invention is coated with lanthanum boride, it is possible to reduce the potential gradient generated near the cathode surface during discharge. Therefore, the energy loss that does not contribute to light emission can be reduced, and the luminous efficiency of the fluorescent lamp can be improved.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view and a sectional view of a flat fluorescent lamp of the present invention, and FIG. 2 is an assembly view of a main part of the flat fluorescent lamp of the present invention. FIG. 3 is a view showing an embodiment of an electrode according to the present invention in which the surface of the electrode is coated with lanthanum boride.

In FIG. 1, a vacuum container (0.04 to 0.8 Pa of mercury and Ar gas is enclosed) in which a low melting point glass (hereinafter referred to as frit) is used as an adhesive in the upper glass substrate 1, the spacer glass 4, and the lower glass substrate 9. Is formed. Second
As shown in the figure, an electrode 2 coated with lanthanum boride is welded to a lead piece 3 and set in a sealed space so as to face each other. The spacer glass 4 has a notch in the central portion, and the exhaust pipe 6 is sealed therein by a frit. A mercury dispenser 8 is inserted in the exhaust pipe 6,
The spacer glass 4 is provided with a recess so that the lead piece 3 can be set. The glass substrates 1 and 9 are coated with phosphors 10 and 11, respectively. And the glass substrate 1,
9 is the frit 5 on the spacer glass 4, and the exhaust pipe 6
Are bonded to the spacer glass 4 and the glass substrates 1 and 9 by the frit 7.

Each part will be described in detail below.

(1) The upper glass substrate 1, the lower glass substrate 9 and the spacer glass 4 are made of soda lime silica glass.

(2) The electrode 2 has a U-shaped cross section shown in FIG. 3 (a), and both ends of a net body formed by knitting stainless steel having a warp of 0.15 mm into a roughness of 30 mesh. Is coated with lanthanum boride having a thickness of about 0.2 μm.

(3) Lead piece 3 is 42Ni-6Cr-Fe that has been subjected to oxidation treatment.
It uses an alloy.

(4) The frits 5 and 7 are made of lead-containing glass in order to enable bonding with a low melting point.

(5) Although the exhaust pipe 6 is exhausted and sealed after Ar is filled, lead-containing glass having a low melting point is used to facilitate the sealing.

(6) The mercury dispenser 8 is inserted before sealing and uses an intermetallic compound of mercury that decomposes into mercury by high frequency heating after sealing.

(7) The phosphors 10 and 11 are applied to the inner surface of each glass substrate by screen printing. The phosphor is a three-wavelength type of R, G, and B, and each is appropriately blended and used.

The fluorescent lamp manufactured as described above was lit at a primary voltage of 6 V, a primary current of 0.33 A, a secondary voltage of 600 V, and a secondary current of 6 mA. The primary side uses a DC power supply (voltage 6V) on the primary side and an inverter on the secondary side has a frequency of about 20 kHz and a duty ratio of about 8%.
I tried to become. The light was turned on for 80 minutes, and the brightness was measured with a brightness meter in front of the glass substrate.
was gotten.

Comparative Example A flat-type fluorescent lamp was manufactured in exactly the same manner as in Example except that the surface of the electrode was not coated with lanthanum boride. When the luminance was measured in the same manner as in the example, the curve B in FIG. 4 was obtained.

From the above, it can be seen that the fluorescent lamp of the present invention in which the electrode is coated with lanthanum boride has a higher brightness than the comparative example in which the lanthanum boride is not coated, that is, the luminous efficiency is improved.

[Advantages of the Invention] In the fluorescent lamp of the present invention, the electrode surface is coated with lanthanum boride to reduce energy loss that does not contribute to light emission and improve luminous efficiency. Therefore, when used as a backlight of various liquid crystal display devices, a bright image can be obtained with low power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view and a cross-sectional view of a flat fluorescent lamp of the present invention, and FIG. 2 is an assembly view of a main part of the flat fluorescent lamp of the present invention.
FIG. 3 is a view showing an embodiment of an electrode according to the present invention, and FIG.
The figure is a view for explaining the brightness of the fluorescent lamp of the present invention.

Claims (1)

[Scope of utility model registration request] 1. A sealed space containing mercury vapor is formed by sealing the peripheries of first and second glass substrates, which are arranged substantially parallel to each other and have a phosphor film on the inner surface thereof, at intervals from each other, What is claimed is: 1. A flat fluorescent lamp, wherein a pair of cold cathode electrodes are arranged to face each other in a sealed space, wherein the surfaces of the electrodes are covered with lanthanum boride.