JP2006089692A - Green light-emitting fluorophor and mercury fluorescent lamp using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorophor settled the problem that green light-emitting fluorophor LaPO4:Ce, Tb excitable by 254 nm wave length mercury emission line is good in efficiency, has sharp emission spectrum, emits yellow-greenish light but is poor in color purity as a green light-emitting fluorophor. <P>SOLUTION: The green light-emitting fluorophor contains zinc (Zn), germanium (Ge) and oxygen (O), wherein zinc is coactivated with manganese (Mn) as the luminescent center, and is represented by formula (1). (Zn<SB>1-x</SB>, Mnx)<SB>2</SB>Ge<SB>y</SB>O<SB>z</SB>(1). (Wherein, x and y are 0<x<1.0 and 0.8≤y<2). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a green phosphor and a fluorescent lamp using the same, and more particularly to a green phosphor excited by a mercury emission line and a mercury fluorescent lamp using the green phosphor.

  Currently, flat display devices (hereinafter referred to as flat displays) are being actively developed. As flat displays, liquid crystal display devices and plasma display devices are mainstream, but field emission display devices (FED: Field Emission Display) and the like are being developed.

  The liquid crystal display device is not the only self-luminous display device among flat-type display devices, but as a backlight, cold cathode fluorescent light using mercury emission lines (wavelengths: 185, 254, 365, 405, 436 nm) as an excitation source. A lamp is used. White-light-emitting cold-cathode fluorescent lamps used in backlights usually emit red, green, and blue fluorescent light by exciting a mixture of red-light-emitting, green-light-emitting, and blue-light-emitting phosphors. I get it.

Among them, LaPO ₄ : Ce, Tb used as a green light emitting phosphor is stable and absorbs ultraviolet light with a wavelength of 254 nm emitted from mercury and emits green light efficiently. However, the efficiency has been improved further from the past ( It is a phosphor that is difficult to increase brightness. In addition, since it shows a yellowish green color from a sharp emission shape having an emission peak at a wavelength of 543 nm due to the Tb ion as the emission center, the white light source used for liquid crystal display devices and the like has a further improvement in color purity. is necessary.

For this reason, improvement of LaPO ₄ : Ce, Tb and research and development of new green phosphors have been carried out, but phosphors that satisfy sufficient performance have not yet been developed.

On the other hand, in the plasma display, plasma is generated in a pixel sealed with a rare gas such as xenon to cause the phosphor to emit light. Since the emission wavelength of the rare gas is ultraviolet light having a wavelength shorter than the emission line of mercury (wavelength 147 nm), a phosphor that emits light by being excited at the wavelength 147 nm that is the emission wavelength of the rare gas is required. Therefore, a green color composed of Zn ₂ (Si _1-x Ge _x ) O ₄ : Mn (0.01 ≦ x ≦ 0.5) used in a rare gas discharge lamp or a plasma display in which a rare gas is sealed. A phosphor has been developed (see Patent Document 1).

  Patent Document 2 discloses a green light emitting phosphor obtained by co-activating ZnO with Ge and Mn as a green phosphor for a field emission display device.

  In the green light emitting phosphor in which Ge and Mn are co-activated in ZnO, the Ge concentration in the ZnO / Ge / Mn ternary phosphor is 28 to 36 mol%, and the Mn concentration is 0.5 to A range of 5 mol% is suitable for a green light-emitting phosphor having an emission center of 530 to 540 nm, and when it is outside this range, it does not show green light emission.

However, green phosphors that are bright, have good color rendering properties, and emit light with good color purity due to mercury emission lines are used as green phosphors for white fluorescent lamps used for backlights of liquid crystal display devices, etc. In addition to lamps and blue fluorescent lamps, they have uses such as green phosphors for green fluorescent lamps for panels for color display, and are strongly demanded not only by industry but also by general consumers.
JP 2003-176482 A JP 2004-99692 A

Conventionally used LaPO ₄ : Ce, Tb, which is a green light-emitting phosphor excited by a wavelength of 254 nm, which is a mercury emission line, is efficient, but the luminous efficiency is improved for further improvement of the efficiency of the fluorescent lamp. Is needed. However, the LaPO ₄ : Ce, Tb phosphor is one of the practical phosphors that have been matured, and it is difficult to improve the efficiency. In addition, the LaPO ₄ : Ce, Tb phosphor has a very steep emission spectrum due to the Tb emission center ion and has a yellowish greenish luminescence. is there.

  The present invention relates to a green light-emitting fluorescent material represented by the formula (1), wherein zinc (Zn), germanium (Ge), and oxygen (O) are contained, and manganese (Mn) is activated by zinc as an emission center. Is the body.

(Zn _1-x , Mn _x ) ₂ Ge _y O _z (1)
(Where x and y are represented by 0 <x <1, 0.8 ≦ y <2)
Furthermore, by using the green phosphor of the present invention together with the red light emitting phosphor and the blue light emitting phosphor in a mercury fluorescent lamp, a white mercury fluorescent lamp with good color purity and high luminous efficiency can be obtained. In addition, a color panel can be configured in combination with the green mercury lamp including the green phosphor, the red mercury lamp including the red phosphor, and the green mercury lamp including the green phosphor of the present invention.

The green phosphor of the present invention has a broader emission than LaPO ₄ : Ce, Tb, which is a green light-emitting phosphor conventionally used in fluorescent lamps using mercury rays, has a good color purity, and is a mercury ray. Light is emitted with high efficiency by ultraviolet light having a wavelength of 254 nm. Therefore, the color rendering property is improved by using the phosphor of the present invention in a mercury fluorescent lamp, and a fluorescent lamp with higher brightness and higher efficiency can be provided.

The inventor is a mercury fluorescent lamp that uses light with a wavelength of 254 nm enclosed in a glass tube as an excitation light source, and can efficiently absorb the wavelength of the mercury line, has better color purity than LaPO ₄ : Ce, Tb, As a result of various studies to obtain a bright green light-emitting phosphor, a formula comprising a combination of Zn, Ge, O, and Mn elements using germanate as a base material and Mn ions as an emission center as an activator. The green light-emitting phosphor represented by (1) was found.

(Zn _1-x , Mn _x ) ₂ Ge _y O ₄ (1)
(Where x and y are represented by 0 <x <1, 0.8 ≦ y <2)
The green light emitting phosphor represented by the formula (1) is excited efficiently by a mercury beam having a wavelength of 254 nm, and has a broader emission shape than the green phosphor LaPO ₄ : Ce, Tb used in conventional fluorescent lamps. It has good green color purity and high luminance.

The green light emitting phosphor represented by the formula (1) is a conventional green phosphor LaPO _{4 by} setting the amount of Ge (corresponding to y) to 1 or more (y <1.0) determined by the stoichiometry. : Brightness is higher than Ce and Tb, but when the Ge composition ratio (y) is 2, Zn is likely to combine with Ge to generate ZnGeO _3, and the structure is likely to deviate from Equation (1). is expected. For this purpose, y needs to be smaller than 2, and preferably y ≦ 0.8.

Unlike the LaPO ₄ : Ce, Tb, the phosphor represented by the formula (1) changes its reflectivity as the value of y increases. When y is 1 or less determined by stoichiometry, the phosphor powder is colored, but when y ≦ 1, it becomes white, and the reflectance increases as y increases.

This example is a mercury fluorescent lamp using mercury light enclosed in a glass tube and having a wavelength of 254 nm as an excitation light source, which can efficiently absorb the wavelength of mercury rays, and has better color purity than LaPO ₄ : Ce, Tb. As a result of various investigations to obtain a high-luminance green light-emitting phosphor, it consists of a combination of elements of Zn, Ge, O, and Mn using germanate as a base material and Mn ions as an emission center as an activator. A green light-emitting phosphor represented by the formula (1) was found.

(Zn _{1 -x} , Mn _x ) ₂ Ge _y O ₄ (1)
(Where x and y are represented by 0 <x <1, 0.8 ≦ y <2)
Next, a method for producing the phosphor of the present invention will be described.

First, as raw materials for phosphor synthesis, zinc compounds such as zinc sulfide (ZnS), zinc carbonate (ZnCO ₃ ) and zinc oxide (ZnO), germanium compounds such as germanium dioxide (GeO ₂ ), and trimanganese tetroxide (Mn) Manganese compounds such as ₃ O ₄ ) and manganese carbonate (MnCO ₃ ) are used. Each of these raw materials is weighed and collected according to the composition formula, and thoroughly mixed by wet or dry methods.

  This mixture is filled in a heat-resistant container such as an alumina crucible, platinum crucible, or carbon crucible and fired at 950 to 1200 ° C. for 3 to 10 hours in an air atmosphere or an oxidizing atmosphere, and the resulting fired product is crushed and sieved. Thus, the phosphor of the present invention can be obtained.

  As materials for supplying Zn, Ge, and Mn, oxides or carbonates are preferably used.

Zinc oxide (ZnO), germanium dioxide (GeO ₂ ) and manganese carbonate (MnCO ₃ ) were weighed to produce phosphors of Examples 1-8.

The composition was determined by determining the composition of Zn, Ge, and Mn from the weights of the weighed zinc oxide (ZnO), germanium dioxide (GeO ₂ ), and manganese carbonate (MnCO ₃ ). And the composition of oxygen was determined from the value obtained by subtracting the weight of Mn. Since all of the phosphors of Examples 1 to 8 had a composition of oxygen close to 4, oxygen in the table was represented as O ₄ .

  In Examples 1 to 4, as Study 1, x was fixed and y was changed. Study 2 is the result of measuring the brightness and reflectivity by changing x while fixing y in the composition (y = 1.2) of Ge that showed the greatest brightness in Study 1. Table 1 shows the measurement results of Examples 1 to 8.

  In addition, the reflectance in Table 1 is a value based on the reflectance of a standard sample showing a stable reflectance at the time of measurement.

  As shown in Table 1, the CIE chromaticity coordinates are (0.336, 0.588) in the conventional example, whereas (0.29 ± 0.06) in all of Examples 1 to 8. 0.6765 ± 0.0035), and as can be seen from the CIE color coordinates in FIG.

FIG. 1 and FIG. 2 show the results of monitoring the excitation intensity monitored for emission at a wavelength of 536 nm and the emission intensity excited at a wavelength of 254 nm using (Zn _0.99 , Mn _0.01 ) ₂ Ge _1.2 O ₄ of Example 3.

  As shown in FIG. 1, the green phosphor of the present invention has a broad excitation intensity distribution having a peak when the wavelength of the excitation light is about 230 nm. From FIG. 1, it can be seen that excitation is efficiently performed with respect to emission of wavelengths 254 and 365 nm, which are emission lines of hydrogen.

  As shown in FIG. 2, the emission intensity excited at a wavelength of 254 nm has a very broad emission shape having a peak at a wavelength of about 536 nm.

  Although the data on the excitation intensity distribution and emission intensity of the other examples are not shown, the shapes of the excitation spectrum measured at the emission monitor wavelength of 536 nm and the emission spectrum measured at the excitation wavelength of 254 nm are similar to each other. showed that.

FIG. 3 is a graph showing an emission spectrum of Example 3 and conventional LaPO ₄ : Ce, Tb at an excitation wavelength of 254 nm. As shown in FIG. 3, the emission spectrum of the phosphor of the present invention is a broad spectrum of 500 nm to 600 nm, whereas the emission spectrum of LaPO ₄ : Ce, Tb has a steep peak at 550 nm. It can be seen that it is a spectrum.

  FIG. 4 is a diagram showing the emission peak intensity and reflectance of the phosphors of Examples 1 to 4 in Study 1 and the Ge composition ratio (y).

  As can be seen from FIG. 4, the emission peak intensity and reflectivity increase as the Ge concentration increases. It can be seen that both the emission peak intensity and the reflectance are in a steady state when y ≧ 1.2.

  FIG. 5 shows the emission peak intensity and the reflectance with respect to the composition ratio of Mn when the composition ratio of Ge is fixed at 1.2 and the Mn composition is changed.

Example 3 and Example 6 were manufactured separately, and even when the composition ratio was the same, both the luminance and the reflectance were different, but this is considered to be a manufacturing variation.
It can be seen that the luminance is the highest in Example 3. At that time, it is 112% of the conventional example, which shows that the phosphor is highly efficient. In addition, the CIE chromaticity coordinates are (0.336, 0.588) in the conventional example, and (0.287, 0.678) in Example 3, indicating that the green color purity is good. . The reflectance is a guideline for the light extraction efficiency of the powder. For example, in the case of Example 1, the powder itself is colored. It can be seen that the white color of the powder increases with the amount of Ge substitution. In the stoichiometric composition, y = 1.0, but in the present invention, it was found that y = 1.0 or more is effective.

  Since the green phosphor of the present invention has good green color purity and high luminance, it is used as a green phosphor for white fluorescent lamps used for backlights of liquid crystal display devices, or red fluorescent lamps and blue fluorescent lamps. It is suitable for use as a green phosphor for a green fluorescent lamp for a panel for color display together with the lamp.

Excitation spectrum of the phosphor of Example 3 (emission monitor wavelength: 536 nm) Emission spectrum of the phosphor of Example 3 (excitation wavelength: 254 nm) Comparison of emission spectrum shape and emission intensity of conventional example and example 3 (excitation wavelength: 254 nm) Study 1: Changes in luminance and reflectance with increasing and decreasing y composition ratio Study 2: Changes in luminance and reflectivity as x composition ratio increases and decreases CIE chromaticity coordinates of conventional example and example 3

Claims (2)

A green light-emitting phosphor represented by the formula (1), wherein zinc (Zn), germanium (Ge), and oxygen (O) are contained, and manganese (Mn) is activated by zinc as a light emission center.
(Zn _1-x , Mn _x ) ₂ Ge _y O _z (1)
(Where x and y are represented by 0 <x <1, 0.8 ≦ y <2)   A mercury fluorescent lamp using the green light-emitting phosphor according to claim 1.

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