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Fluorescent lamp, backlight unit, and liquid crystal display device

a technology of liquid crystal display device and backlight unit, which is applied in the direction of discharge tube/lamp details, discharge tube luminescnet screen, instruments, etc., can solve the problems of troublesome operation of cesium compound application and inability to start the fluorescent lamp immediately when a starting voltage is applied, and achieve excellent in-dark starting characteristics and improved in-dark starting characteristics.

Inactive Publication Date: 2009-01-29
TERADA TOSHIHIRO +10
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a fluorescent lamp with improved in-dark starting characteristics that can be easily achieved without troublesome operation. The fluorescent lamp includes a glass bulb with a discharge space inside, electrodes at both ends of the glass bulb, and a protective layer formed on the inner surface of the glass bulb, except at least one end. The protective layer contains an alkaline metal that can be precipitated from the glass bulb. The invention also provides a backlight unit and a liquid crystal display device with the improved in-dark starting characteristic. The invention aims to improve the in-dark starting characteristic of the fluorescent lamp by using a protective layer with an alkaline metal that can be precipitated from the glass bulb.

Problems solved by technology

These fluorescent lamps, however, have the following problem.
In darkness, it takes time to light up a fluorescent lamp, that is, the fluorescent lamp cannot be started immediately when a starting voltage is applied.
However, though the in-dark starting characteristic can certainly be improved, this technique requires a troublesome operation of applying the cesium compound to the inner surface of the glass bulb.

Method used

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  • Fluorescent lamp, backlight unit, and liquid crystal display device
  • Fluorescent lamp, backlight unit, and liquid crystal display device
  • Fluorescent lamp, backlight unit, and liquid crystal display device

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

1. Liquid Crystal Display Device

[0086]FIG. 1 shows a liquid crystal television 1, with one part of its front surface being omitted.

[0087]As shown in the drawing, the liquid crystal television 1 includes a liquid crystal display unit 2 and a backlight unit 3. The liquid crystal television 1 has a 32-inch screen size as one example.

[0088]The liquid crystal display unit 2 includes a color filter substrate, a liquid crystal, and a TFT substrate (not illustrated), and forms a color image based on an external image signal under control of a driving module (not illustrated).

[0089]The backlight unit 3 includes a plurality of fluorescent lamps 20 as a light source, and is located on the back of the liquid crystal display unit 2. The backlight unit 2 irradiates the liquid crystal display unit 2 from the rear.

2. Backlight Unit

[0090]FIG. 2 is a schematic perspective view showing a construction of the backlight unit 3 used in the liquid crystal television 1, according to the first embodiment. To...

second embodiment

[0136]In the first embodiment, the phosphor layer 23 is composed of the rare-earth phosphors that are the red phosphor (Y2O3: Eu), the green phosphor (LaPO4: Ce, Tb), and the blue phosphor (BaMg2Al16O27: Eu, Mn). However, the phosphor layer may be composed of other phosphors.

[0137]A second embodiment of the present invention describes the case where the phosphor layer is composed of phosphors other than those used in the first embodiment.

1. Structure of the Phosphor Layer

[0138]FIG. 7 is an enlarged schematic view showing a phosphor layer 101 according to the second embodiment, and FIG. 8 is a composition diagram of the phosphor layer 101.

[0139]As shown in FIGS. 7 and 8, the phosphor layer 101 is composed of BaMg2Al16O27: Eu2+ (BAM) as a blue phosphor 101B, BaMg2Al16O27: Eu2+, Mn2+ (BAM: Mn2+) as a green phosphor 101G, and Y2O3: Eu3+ (YOX) as a red phosphor 101R.

[0140]The blue phosphor 101B and the green phosphor 101G are phosphors that absorb ultraviolet light of 313 nm in wavelengt...

third embodiment

1. Structure of the Protective Layer

[0182]The first embodiment does not particularly describe a specification of the protective layer. A third embodiment of the present invention describes a protective layer that is composed of an aggregate of metal oxide particles.

[0183]Though yttrium oxide (Y2O3) is used in this protective layer, other materials such as alumina (Al2O3) may instead be used.

[0184]It is preferable for an average thickness of the protective layer to be no more than 2 μm, and a surface roughness of the protective layer to be no more than 1 μm. Alternatively, it is preferable for the average thickness of the protective layer to be no more than 2 μm, and an average cross sectional area of each closed hole in the protective layer to be no more than 0.1 μm2.

2. Protective Layer Formation Method

[0185]A method of forming the protective layer of the third embodiment in a lamp manufacturing process is explained below, with reference to FIG. 12.

[0186]First, a protective layer su...

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Abstract

A backlight unit has an external electrode fluorescent lamp in a housing. The external electrode fluorescent lamp includes a glass bulb having a discharge space inside, and electrodes around both ends of the glass bulb. A protective layer and a phosphor layer are formed on an internal surface of the glass bulb in this order. The glass bulb is made of soda glass, and sodium oxide precipitated from this soda glass appears on part of the internal surface of the glass bulb where the protective layer is not formed, so as to be exposed to the discharge space.

Description

RELATED APPLICATIONS[0001]This application is a divisional application of U.S. patent application Ser. No. 11 / 429,767 filed on May 8, 2006 which is based on applications Nos. 2005-141745, 2005-197248, 2005-219982, 2005-221206, and 2006-017275 filed in Japan, the contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a fluorescent lamp having electrodes at both ends of a tubular glass bulb, and a backlight unit and a liquid crystal display device including the fluorescent lamp as a light source. The present invention in particular relates to techniques for improvement in in-dark starting characteristic.[0004]2. Related Art[0005]Due to recent increases in size of liquid crystal display screens, the demand for backlight units for large-screen use is on the increase. Fluorescent lamps, such as external electrode fluorescent lamps having electrodes outside a glass bulb and cold cathode fluore...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02F1/13357H01J63/04G09F13/08
CPCG02F1/133604H01J61/302H01J65/00H01J61/35H01J61/33G02F1/1335
Inventor TERADA, TOSHIHIROMURAKAMI, MASANOBUMATSUO, KAZUHIROONO, TAIZOUWADA, HIDEKITSUTSUMI, SHINGOKAWASAKI, MITSUHARUARATA, HIROYUKIHABUTA, YUKOMATSUURA, TOMOKAZUYAMASHITA, HIROFUMI
Owner TERADA TOSHIHIRO