JPH09111235A - Phosphor and fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phosphor with ultraviolet- or blue-luminescence, sharp in emission spectrum distribution when excited by ultraviolet light and low in deterioration with the lapse of time, and to obtain a fluorescent lamp low in luminescent efficiency depression even after used for a long time, thus suitable as a light source for coloring matter setting. SOLUTION: This phosphor has the following characteristics: the emission peak wavelength of its emission spectrum distribution when excited by ultraviolet light is 420-430nm, and the emission intensity at wavelength 410nm is <=0.4 when the emission intensity at the emission peak wavelength is assumed as 1. The other objective fluophor has a composition expressed by the formula (Sr1-a-b-c-d Caa Bab Mgc Eud )2 P2 O7 (0<=(a)<=0.3; 0<=(b)<=0.3; 0<=(c)<=0.3; 0.001<=(d)<=0.1; 0.1<=(a+b+c)<=0.4), and is obtained by forming a phosphor film containing this phosphor on the inner surface of a glass bulb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor and a fluorescent lamp, and in particular, it produces ultraviolet or blue-violet fluorescence which forms a narrow emission spectrum distribution when excited by ultraviolet rays and is suitable as a light source for fixing diazo dyes and the like. The present invention relates to a fluorescent substance that emits light, and a fluorescent lamp that is formed by using the fluorescent substance and that does not deteriorate a dye other than a dye that is sensitive to a specific wavelength and that has a small decrease in emission intensity.

[0002]

2. Description of the Related Art With the recent breakthrough in color printing technology, copying machines capable of full-color printing, printers for personal computers, etc. are becoming widespread.
In addition to various methods such as sublimation transfer method, heat development method, color image transfer method, electrophotographic method, electrostatic recording method, ink jet method, etc., which have been developed up to now, full-color printing method has recently been improved by heat-sensitive method. The method is often adopted and is used in various full-color printing devices.
With this heat-sensitive method, it is not necessary to replenish consumable items such as ink cartridges and developing liquids, maintenance is easy (maintenance), and because no waste is discharged, environmental pollution is low and safety is excellent. It has the feature that it has been attracting attention as an excellent printing method.

Printing apparatuses using the above-described full-color heat-sensitive system employ a system in which three types of organic dyes of cyan, yellow, and magenta are colored to form a color. Then, using a thermal paper coated with a thermosensitive coloring layer consisting of dyes and color formers, in order to fix the diazo dye that has been colored by heat, the thermosensitive paper is irradiated with ultraviolet rays to decompose the unreacted diazo dye and image Has been adopted. As the ultraviolet light source, various fluorescent lamps that emit fluorescence of a predetermined wavelength are used. Examples of the phosphor for ultraviolet light emission include a europium-activated strontium pyrophosphate (Sr ₂ P ₂ O ₇ : Eu) phosphor having an emission peak wavelength at 420 nm and a europium-activated strontium borate (Sr) having an emission peak wavelength at 370 nm. _{The 2} B ₄ O ₇ : Eu) phosphor has been put to practical use because of its relatively high luminous efficiency.

Here, diazo dyes generally used for thermal paper are two colors of yellow and magenta.
Among them, the magenta color is decomposed by ultraviolet rays having a wavelength λ of around 365 nm to become colorless. And in heat-sensitive full-color printing equipment that has been put to practical use up to now,
As a light source for fixing the magenta color, an ultraviolet light emitting fluorescent lamp having a fluorescent film made of europium-activated strontium tetraborate (SrB ₄ O ₇ : Eu) phosphor is mounted.

The above-mentioned europium-activated strontium tetraborate phosphor has a property of emitting ultraviolet rays having a wavelength λ of 367 nm when irradiated with ultraviolet rays having a wavelength λ of 254 nm.

Further, in the development of a full-color printing apparatus adopting a heat-sensitive system, the reason why the spectral distribution of the europium-activated strontium tetraborate phosphor matches the decomposition sensitivity wavelength distribution of the diazo dye expressing magenta color,
Further, the above-mentioned phosphor has a history of being adopted as a phosphor for an ultraviolet fluorescent lamp for dye fixing of full-color heat-sensitive paper, because it has a better luminous efficiency than other phosphors that emit light of the same wavelength.

[0007]

However, when a fluorescent lamp using the above-mentioned conventional phosphor is used as a light source for dye fixing, since the bottom of the emission spectrum distribution of the phosphor widened by ultraviolet excitation is widened, There is a problem that a dye other than the originally intended kind of dye is fixed, and the emission characteristics of other dyes are deteriorated.

For example, the conventional europium-activated strontium pyrophosphate phosphor having an emission peak wavelength of 420 nm has a shape of the emission scuttle distribution in which the emission intensity at 410 nm is 0.6 when the emission intensity at the peak wavelength is 1. And the emission intensity at 400 nm is 0.2
It has a broad distribution shape.
In this way, since strong emission energy exists on the shorter wavelength side than the originally intended wavelength, there is a problem that a dye which is not originally intended is exposed and deteriorated. Once
The dye that has been exposed to light does not sufficiently exhibit its original color-developing properties, which causes a problem that the color reproducibility is deteriorated. In recent years, in a situation where a copy image with high definition and excellent color reproducibility is required, a measure for reducing the deterioration of the dye is required.

Further, the conventional europium-activated strontium pyrophosphate phosphor is extremely deteriorated with time,
When it is used as a phosphor of a light source lamp for dye fixing (ultraviolet light emitting fluorescent lamp) in a heat-sensitive full-color printing device, there is a problem that the fixing process operation becomes complicated.
That is, in the ultraviolet light emitting fluorescent lamp using the above-mentioned phosphor, there is a problem that the luminous flux is remarkably decreased with the passage of lighting time and the life is shortened. Therefore, in order to maintain a certain level of emission intensity, it was necessary to frequently replace the fluorescent lamp. Further, in the case of a heat-sensitive full-color printing device using the ultraviolet light fluorescent lamp, the deterioration degree of the luminous flux is monitored by a sensor, and the monitoring result is fed back to the irradiation time of the lamp to the thermal paper, so that the image quality is improved. It is equipped with a mechanism to keep the temperature constant. As a result, there has been a problem that the configuration of the printing apparatus is complicated, and the printing time is prolonged due to the deterioration of the fluorescent material of the lamp, and the printing efficiency is reduced.

The present invention has been made in order to solve the above problems, and an ultraviolet or blue light emitting phosphor having a sharp emission spectrum distribution when excited by ultraviolet rays and little deterioration with time, and an object of use. It is an object of the present invention to provide a fluorescent lamp, in which the emission energy is concentrated in the wavelength range, the emission efficiency is less reduced even when used for a long time, and which is suitable as a light source for dye fixing.

[0011]

In order to achieve the above object, the present inventor has added various elemental components such as an alkali metal element and an alkaline earth metal element to a phosphor having an emission peak wavelength near 420 nm. As a phosphor composition, and using the composition to prepare a fluorescent lamp with a phosphor layer formed, the added elemental components and the added amount depend on the emission spectrum distribution shape of each fluorescent lamp and the luminous efficiency and deterioration characteristics over time. The influences were comparatively investigated by experiments. As a result, the conventional europium-activated strontium pyrophosphate contains an alkali metal such as Ca (calcium), Ba (barium), and Mg (magnesium) at a predetermined ratio, so that it emits light as compared with a conventional phosphor. An ultraviolet light emitting phosphor having a sharp spectrum distribution and little deterioration over time was obtained. Further, by forming a fluorescent lamp for fixing a dye by depositing this phosphor on the inner wall of the glass tube, dyes other than the dyes that are sensitive to a specific wavelength are less likely to deteriorate, and the luminous efficiency is not deteriorated over time. We have found that a fluorescent lamp with few high characteristics can be obtained for the first time. The present invention has been completed based on the above findings.

That is, the phosphor according to the present invention has an emission peak wavelength of 420 nm or more and 430 nm or less in the emission spectrum distribution when the phosphor is excited by ultraviolet light, and the emission intensity at the emission peak wavelength is 1. 410nm
It is characterized in that the emission intensity at the wavelength is 0.4 or less. The emission intensity at a wavelength of 400 nm is 0.1
It is good to be the following. Further, the half-value width of the emission spectrum distribution is preferably 30 nm or more and 35 nm or less.

Further, the phosphor is represented by the general formula (Sr _{1 -abcd} C
a _a Ba _b Mg _c Eu _d ) ₂ P ₂ O ₇ (where 0 ≦ a ≦
0.3, 0 ≤ b ≤ 0.3, 0 ≤ c ≤ 0.3, 0.001
≦ d ≦ 0.1, 0.1 ≦ a + b + c ≦ 0.4). Further, in the above general formula, the total content (a + b) of Ca and Ba is 0.
It is desirable to set it in the range of 1 to 0.3.

Further, the fluorescent lamp according to the present invention is characterized in that the phosphor film containing the above-mentioned phosphor is formed in a film shape on the inner surface of the glass bulb.

Here, as shown by the above general formula, C
Europium-activated strontium pyrophosphate containing a, Ba, and Mg is a phosphor that emits ultraviolet light having a wavelength of 420 to 430 nm by being irradiated with ultraviolet light having a wavelength of 254 nm, and is a light source lamp for fixing a diazo dye or the like. Used as a phosphor of.

Ca, Ba, and Mg contained in the phosphor represented by the above general formula have the effects of shifting the emission peak wavelength to the longer wavelength side and improving the emission efficiency and deterioration of the phosphor. However, when the contents a, b, and c of Ca, Ba, and Mg each exceed 0.3 in atomic ratio, the luminous efficiency decreases and the practicality is lost. Therefore Ca,
Each content of Ba and Mg is set to 0.3 or less. Further, the total content (a + b + c) of Ca, Ba, and Mg is preferably in the range of 0.1 to 0.4. Especially Ca and B
By setting the total content (a + b) of a in the range of 0.1 to 0.3, the luminous efficiency and the degree of deterioration can be further improved.

Eu (europium) acts as an activator (activator) for increasing the luminous efficiency of the phosphor, and is added in an atomic ratio of 0.001 to 0.1 with respect to Sr (strontium). If the addition ratio is less than 0.001, the effect of improving the luminous efficiency is small. On the other hand, if the addition ratio exceeds 0.1, coloring tends to occur, which rather impairs the luminous efficiency of the lamp.

The phosphor represented by the above general formula is added at 254 nm.
The shape of the emission spectrum distribution obtained when excited by ultraviolet rays of No. 1 is such that the emission peak wavelength is in the range of 420 to 430 nm, and when the emission intensity at the emission peak wavelength is 1, the emission intensity at the wavelength of 410 nm is 0. It is 4 or less, the emission intensity at 400 nm is 0.1 or less, and the full width at half maximum is in the range of 30 to 35 nm.

According to the phosphor having the above structure, the emission spectrum distribution is sharp, and the emission energy is concentrated in the wavelength range intended for use. Therefore, when this fluorescent material is used to form a fluorescent lamp for fixing a dye in a color copying machine, there is little risk of degrading other dyes that are sensitive to wavelengths other than the intended use. Therefore, a copied image having excellent color reproducibility can be obtained.

Further, since the components and composition of the phosphor are appropriately adjusted, deterioration of the phosphor can be effectively prevented. By using this phosphor, the emission intensity is high and the emission efficiency is less likely to decrease. It becomes possible to provide a fluorescent lamp. This fluorescent lamp is extremely useful as a light source for fixing a diazo dye or the like in a color copying machine.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described.
This will be described more specifically with reference to the following examples.

Examples 1 to 7 (NH ₄ ) ₂ HPO ₄ powder and SrHPO ₄ as phosphorus source
Powder, CaHPO ₄ powder, SrHPO ₄ powder, SrCO ₃ powder as strontium source, CaHPO ₄ powder, CaCO ₃ powder as calcium source, BaHPO ₄ powder, BaCO ₃ as barium source
Prepare powder, MgCO ₃ powder as magnesium source,
Prepare MgO powder and use Eu ₂ O ₃ as a source of europium.
Each powder was prepared.

Next, the respective raw material powders were weighed so as to have the stoichiometric ratio of the phosphor shown in the left column of Table 1 and mixed sufficiently. The obtained raw material mixture is heated at a temperature of 900 to 1 in a reducing atmosphere.
The phosphors according to Examples 1 to 7 were prepared by firing at 000 ° C. for 3 to 5 hours, pulverizing the obtained fired product, and further subjecting it to dispersion treatment.

Comparative Examples 1 to 3 Phosphors according to Comparative Example 1 were prepared in the same manner as in Example 1 except that the components Ca, Ba and Mg were not added at all. In addition, the total content of Ca and Ba components (a +
A phosphor according to Comparative Example 2 was prepared in the same manner as in Example 1, except that the composition was set so that b) became an excessive amount. Further, Comparative Example 3 was carried out under the same conditions as in Example 6 except that the Ca component content (a) was set to an excessive amount of 0.5.
Was prepared.

In order to evaluate the characteristics of the phosphors according to the above-mentioned Examples and Comparative Examples, each phosphor was irradiated with ultraviolet rays having a wavelength of 254 nm to be excited, and the obtained emission spectrum had a peak wavelength of 410 nm. And various parameters such as emission intensity and half width at 400 nm and deterioration characteristics of emission intensity were measured.

Further, a fluorescent lamp for dye fixing of a color copying machine was prepared using each of the phosphors, and the fluorescent lamp was subjected to a dye fixing operation of color printing to measure the deterioration level of the diazo dye.
The deterioration level of the dye was measured as the deterioration rate of the diazo dye having a photosensitive peak at 370 nm after the fixing process.
The fluorescence intensity is 4 when excited by 254 nm ultraviolet light.
The emission intensity at 20 nm is shown, and the comparative example 1 using the conventional phosphor is shown as a reference value (100). Further, the deterioration characteristic of the emission intensity was measured by measuring the emission intensity before and after irradiating each phosphor with 185 nm ultraviolet ray in vacuum for 1 hour, and expressed as a reduction rate from the initial value. The measurement results are shown in Table 1 below. Further, the emission spectrum distributions of the phosphors according to Example 1 and Comparative Example 1 are shown in FIG.

[0027]

[Table 1]

As is clear from the results shown in Table 1 and FIG. 1 attached heretofore, the phosphors according to Examples 1 to 7 containing Ca, Ba components and the like in appropriate amounts were the conventional Eu-activated Sr ₂ P ₂
The peak wavelength is shifted to the long wavelength side as compared with the O ₇ phosphor, and the half-value width of the emission spectrum distribution is 32 to 35.
nm, and the distribution shape is sharp. That is, when the emission intensity at 420 nm in each emission spectrum distribution is 1, the emission intensity at 410 nm is 0.4 or less, and the emission intensity at 400 nm is 0.1 or less, and the emission energy especially on the short wavelength side is small. Therefore, when a fluorescent lamp for dye fixing is formed by using this phosphor, the deterioration rate of the dye exposed at 370 nm is 20.
% Or less, and the color reproducibility was improved.

On the other hand, in the phosphor according to Comparative Example 1,
As shown in FIG. 1, the peak wavelength is 420 nm,
Since the emission intensity in the short wavelength region of nm is as high as 0.6, the deterioration rate of the dye sensitized at 370 nm reaches 50%, and it was found that the color reproducibility deteriorates.

Further, in the phosphors of Comparative Examples 2 and 3 in which the Ca component and / or the Ba component were added in an excessive amount, the peak wavelength was shifted to the long wavelength side of 433 to 435 nm, and the full width at half maximum was widened. The emission intensity (output) near 420 nm becomes excessively low, which makes it difficult to meet the original purpose of fixing.

The fluorescent lamp using the phosphor emitting ultraviolet or blue light according to the present embodiment has a sharp emission spectrum distribution on the short wavelength side, and exhibits an emission spectrum distribution suitable as a light source for fixing a diazo dye or the like.

Further, in the fluorescent lamp using the phosphor according to each example, the deterioration characteristic of the emission intensity is 20 to 25%.
However, in the comparative example, the value was as high as 33 to 40%. That is, by using the phosphor according to this example, it was possible to obtain a fluorescent lamp having high emission intensity and little decrease in emission efficiency.

[0033]

As described above, according to the phosphor of the present invention, the emission spectrum distribution is sharp and the emission energy is concentrated in the wavelength range intended for use. Therefore, when this fluorescent material is used to form a fluorescent lamp for fixing a dye in a color copying machine, there is little risk of degrading other dyes that are sensitive to wavelengths other than the intended use. Therefore, a copied image having excellent color reproducibility can be obtained.

Further, since the components and composition of the phosphor are adjusted appropriately, the deterioration of the phosphor can be effectively prevented. By using this phosphor, the emission intensity is high and the decrease in emission efficiency is small. It becomes possible to provide a fluorescent lamp. This fluorescent lamp is extremely useful as a light source for fixing a diazo dye or the like in a color copying machine.

[Brief description of the drawings]

FIG. 1 is a graph showing emission spectrum distributions of a phosphor according to the present invention and a conventional phosphor.

Claims (6)

[Claims] 1. The emission peak wavelength of the emission spectrum distribution when the phosphor is excited by ultraviolet rays is 420 nm or more and 430 nm or more.
And the emission intensity at the emission peak wavelength is 1 or less.
, The emission intensity at a wavelength of 410 nm is 0.
A phosphor having a number of 4 or less. 2. The emission intensity at a wavelength of 400 nm is 0.
It is 1 or less, The fluorescent substance of Claim 1 characterized by the above-mentioned. 3. The phosphor according to claim 1, wherein the emission spectrum distribution has a full width at half maximum of 30 nm or more and 35 nm or less. 4. The phosphor has the general formula (Sr _{1 -abcd} Ca _a
Ba _b Mg _c Eu _d ) ₂ P ₂ O ₇ (provided that 0 ≦ a ≦ 0.
3, 0 ≤ b ≤ 0.3, 0 ≤ c ≤ 0.3, 0.001 ≤ d
The phosphor according to claim 1, having a composition represented by ≦ 0.1, 0.1 ≦ a + b + c ≦ 0.4). 5. A compound represented by the general formula (Sr _{1 -abcd} Ca _a Ba _b M
g _c Eu _d ) ₂ P ₂ O ₇ (provided that 0 ≦ a ≦ 0.3, 0 ≦
b ≦ 0.3, 0 ≦ c ≦ 0.3, 0.001 ≦ d ≦ 0.
1, 0.1 ≦ a + b ≦ 0.3), which is a phosphor. 6. A fluorescent lamp comprising a phosphor film containing the phosphor according to claim 1 formed on the inner surface of a glass bulb.