JP2739061B2 - Method for producing infrared stimulable phosphor, infrared stimulable phosphor, and infrared-visible conversion element using infrared stimulable phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an infrared stimulable phosphor, an infrared stimulable phosphor, and an infrared-visible conversion device using the infrared stimulable phosphor.

[0002]

2. Description of the Related Art Infrared stimulable phosphors are known as blue, green, and red when irradiated with ultraviolet light, visible light, or the like, and then irradiated with infrared light. It is a phosphor that emits light in the visible region, and is widely used for detecting infrared light from a YAG laser or a semiconductor laser. As an infrared stimulable phosphor, a phosphor obtained by adding two kinds of activators such as europium and samarium to a base material composed of an alkaline earth metal sulfide such as calcium sulfide or selenide is widely used. Conventionally, as a method for producing this infrared stimulable phosphor, first, an activator is mixed with a base material and fired to produce a phosphor material in which the activator is uniformly diffused in the base material, and this is crushed. A powdered method has been used. The reason for pulverizing after firing is that the raw materials of the fluorescent material are fused together to form a lump by firing, which is inconvenient for practical use. In order to recover the deterioration of the phosphor characteristics due to the pulverization, the phosphor after the pulverization is further subjected to a heat treatment. When an infrared-visible conversion device is manufactured using the infrared stimulable phosphor thus manufactured, it is inconvenient to use the powder as it is because it is inconvenient for practical use. It has been applied on a paper surface and sandwiched by a sealing layer such as a transparent synthetic resin film to form an element.

[0003]

In a conventional infrared-visible conversion element manufactured by mixing and applying a powdered phosphor with a binder, the phosphor-coated portion is a mixed layer of phosphor particles and a binder. In addition, the volume ratio of the phosphor per unit volume (hereinafter, referred to as the volume ratio) is always lower than the case where the layer is formed only by the phosphor particles. Further, there is a disadvantage that the infrared-visible conversion efficiency is substantially lower than the infrared-visible conversion efficiency of the phosphor itself due to the absorption of infrared rays by the binder. In order to solve the above-mentioned drawbacks, the present inventors processed the phosphor powder into a plate by compression molding without using a binder to form an infrared detection unit, thereby increasing the volume ratio of the phosphor and increasing the infrared-visible conversion. Tried to improve efficiency. However, according to this method, the stress generated by the compression causes distortion or defects in the phosphor and deteriorates the phosphor characteristics, so that the infrared-visible conversion efficiency decreases,
In addition, it has been newly found that there is a problem that sufficient robustness for practical use cannot be obtained only by compression molding.
The present invention has been proposed to improve the above-mentioned drawbacks, and its object is to provide an infrared stimulable phosphor having a high phosphor volume ratio, and an increased infrared-visible conversion efficiency and infrared-visible conversion time. To provide an infrared stimulable phosphor and an infrared-visible conversion element using the infrared stimulable phosphor.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises compression molding a phosphor raw material powder comprising a sulfide or selenide of an alkaline earth metal and an activator, or a flux thereof. Later, this compression molded phosphor
An object of the present invention is to provide a method for producing an infrared stimulable phosphor, which comprises subjecting a raw material powder to a heat treatment without contact with a container or a furnace core tube . Furthermore, the present invention is an alkali
Earth metal sulfide or selenide and activator, or
Compacts the phosphor raw material powder consisting of
After this, this compression molded phosphor raw material powder is
Or infrared heating produced by heating without contacting the furnace core tube
It is an object of the present invention to use a phosphor . Further, the present invention, the infrared stimulable phosphor is sandwiched from both sides by a sealing layer,
At least one of the encapsulation layers is a clear body.
Infrared visible conversion element formed by using the infrared accelerated phosphorescence fluorescent to symptoms in which mode of the invention.

[0005]

In the manufacturing method of the present invention, since the infrared detecting section is formed by compression molding without using a binder, the volume ratio of the phosphor is high, and the infrared detecting section having no infrared absorption loss by the binder can be formed. By performing a heat treatment after the compression molding, not only the deterioration of the phosphor characteristics caused by the compression can be recovered, but also the mutual fusion and the grain growth of the phosphor particles can be achieved, so that the robustness and the phosphor are improved. Since the infrared-visible conversion efficiency is improved, the infrared-visible conversion efficiency is high, and an infrared stimulable phosphor having sufficient strength for practical use can be produced. Furthermore, the compression molded raw material rod is sintered while maintaining its shape, so that the area in contact with the container and the furnace core tube can be reduced as compared with the case where the raw material rod is sintered as it is in powder form. As compared with the method, it is possible to manufacture a phosphor having a high conversion efficiency by suppressing the characteristic deterioration due to contamination and suppressing the deterioration. In addition, if the heat treatment is performed in a state of being suspended in the furnace core tube by a wire or the like, the heat treatment can be performed without any contact with the container or the furnace core tube, so that deterioration of characteristics due to contamination can be prevented, and fluorescent light with high conversion efficiency can be obtained. The body can be manufactured. Infrared stimulable phosphor is a phosphor that emits visible light by emitting the energy accumulated by excitation by infrared irradiation.If infrared irradiation is continued, the accumulated energy is consumed and infrared-visible conversion is not performed. However, since the infrared stimulable phosphor produced by the production method of the present invention has a high volume ratio of the phosphor, the amount of excitation energy accumulated in the infrared detection unit is large, and the time during which infrared detection is possible is possible. Has the advantage of being long.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a basic configuration example of the infrared-visible conversion element of the present invention. At least one of the infrared-visible conversion elements has transparent members 11 and 12 and an infrared stimulable phosphor 13, and the infrared stimulable phosphor 13 is
And 12 are held between them.

FIGS. 2A and 2B are views showing the configuration of the infrared-visible conversion element manufactured in the present embodiment. FIG. 2A is a front view, and FIG. 2B is a cross-sectional view taken along line AA in the front view. This infrared-visible conversion element has transparent thermocompression bonding films 21 and 22, an infrared stimulable phosphor 23 and a cardboard 24, and the infrared stimulable phosphor 23 is provided in a hollow portion of the cardboard 24 and is further transparent. It is held between the thermocompression bonding films 21 and 22.

Next, an element manufactured by subjecting a raw material powder to compression molding and then subjecting it to heat treatment in a non-contact manner with a container and a furnace core tube and a method of manufacturing the element will be described. In the present embodiment, since the heat treatment is performed without the raw material rod being in contact with the container and the furnace core tube, an element with high sensitivity can be obtained without impurities being mixed into the raw material rod from the container or the furnace core tube. FIG. 3 is a diagram showing a manufacturing apparatus and a raw material attaching method used in the present embodiment. This manufacturing apparatus has an electric furnace 41, a furnace core tube 42, a raw material rod support shaft 43, and a raw material rod support shaft driving mechanism 44. The electric furnace 41 has a cylindrical shape having a cavity therein, and has an internal cavity. The furnace core tube 42 made of alumina is installed vertically, and a raw material rod support shaft 43 for hanging a raw material rod 45 is provided above the furnace core tube 42. The raw material rod support shaft has uneven heating of the sample. A drive mechanism 44 for moving the raw material rod support shaft 43 up and down inside the furnace core tube 42 and rotating the same in order to prevent this is attached. The raw material rod 45 is hung on the raw material rod support shaft 43 using a molybdenum wire 46. A raw material powder is prepared by mixing europium oxide powder and samarium oxide powder with calcium sulfide powder at a weight ratio of 500 ppm and 150 ppm, respectively. The raw material powder is formed into a rod having a diameter of about 2 cm by a rubber press to obtain a raw material rod.
This raw material rod is placed in an electric furnace, and
Heat treatment. The higher the heat treatment temperature, the faster the phosphor characteristics can be improved in a short time. At 1200 ° C., it takes about 1 hour at 1500 ° C. to obtain a phosphor having the same properties as the phosphor subjected to the heat treatment. It was enough. The raw material rod 45 formed by the rubber press is provided with a hole in one end thereof in the longitudinal direction and the vertical direction, and the molybdenum wire 4 is formed there.
And suspended on the raw material rod support shaft 43 through the furnace core tube 4.
Heat treatment was performed by rotating up and down in 2 and rotating. During the heat treatment, an inert gas such as argon or a mixed gas of an inert gas and hydrogen sulfide was flowed into the furnace tube in order to prevent the raw material from being oxidized. By this heat treatment, the phosphor powder particles are fused to make the raw material rod robust, and the grains grow to improve the infrared-visible conversion efficiency. Furthermore, this raw material rod is about 1-2 mm
It is cut perpendicularly to the longitudinal direction at intervals of approximately to obtain a plate-shaped phosphor. The thickness is set to be about 1 to 2 mm in order to make the plate-shaped phosphor compact and keep it suitable for carrying while maintaining appropriate strength. Also, with this thickness, the visible light generated by the infrared-visible conversion in the phosphor passes through the phosphor plate, and visible light can be detected from both sides of the plate surface. For example, the convenience is increased. As a result of examining the average particle size of the phosphor powder using a scanning electron microscope, it was found that the average
In contrast to the phosphor of 30 μm, the phosphor produced by this production method has a large particle size of 400 to 600 μm, and the infrared-visible conversion efficiency also shows a value of 5 times or more. It was clarified that the infrared-visible conversion efficiency of the phosphor was improved.

Further, as shown in FIGS. 2 (a) and 2 (b), cardboard prepared by cutting a hole large enough to accommodate the phosphor plate from the phosphor plate manufactured by the present manufacturing method is prepared. A structure in which a phosphor plate is placed in a hollow portion, and the phosphor plate is further sandwiched by a transparent thermocompression-bondable film and heated and pressed to be sandwiched by a transparent sealing layer made of a transparent thermocompression-bondable film. An infrared-visible conversion element was produced. The hole for installing the phosphor plate may be in any part of the cardboard, but is provided in a narrow place near the periphery for convenient use for infrared detection. The thickness of the cardboard used in the production of the present element may be any thickness as long as the element has sufficient strength, but the thickness is substantially equal to the thickness of the phosphor plate for the purpose of portability and protection of the phosphor plate. It is desirable to have the In addition, the size of the element itself was set to be equal to or smaller than that of a commercially available telephone card from the viewpoint of portable convenience. This element and an infrared light having the same intensity as a conventional infrared-visible conversion element in which a binder and a fluorescent substance are mixed and coated to the same size as the phosphor plate used in this element to form an infrared-visible conversion section are formed. When the infrared-visible conversion efficiency was measured by irradiation, the infrared-visible conversion efficiency of the device of the present invention was 20 times that of the conventional device, and an infrared-visible conversion device having a high infrared-visible conversion efficiency was obtained. Further, when the decay of the converted light was examined by continuously irradiating the infrared ray, the initial intensity was 1%.
The time to become / 2 is about 30 times that of the conventional device, indicating that the infrared-visible conversion time is long.

[0010]

By using the manufacturing method of the present invention in the manufacturing method of the infrared-visible conversion element, the volume ratio of the phosphor in the infrared detecting section can be increased, so that the effective infrared-visible conversion efficiency can be improved. In addition, the infrared-visible conversion time increases, and the heat treatment can reduce the defects in the phosphor and increase the particle size, thereby increasing the infrared-visible conversion efficiency of the phosphor itself. The present invention has an effect of providing an infrared stimulable phosphor having a long visible conversion time and an infrared-visible conversion element using the infrared stimulable phosphor. Also book
In the method for producing an infrared stimulable phosphor according to the present invention, compression-molded
Phosphor raw material powder in a container or furnace
Because the heat treatment is performed, the raw material rod
An element having high sensitivity can be obtained without causing impurity contamination therein.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a basic configuration example of an infrared-visible conversion element of the present invention.

FIGS. 2A and 2B are diagrams showing a configuration of an infrared-visible conversion element manufactured in this example, where FIG. 2A is a front view and FIG. 2B is a cross-sectional view.

FIG. 3 is a perspective view showing a manufacturing apparatus and a raw material attaching method used in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 At least one transparent sealing layer 12 At least one transparent sealing layer 13 Infrared stimulable phosphor 21 Transparent thermocompression-bondable film 22 Transparent thermocompression-bondable film 23 Infrared stimulable phosphor 24 Cardboard 41 Electricity Furnace 42 Furnace tube 43 Raw material rod support shaft 44 Raw material rod support shaft drive mechanism 45 Raw material rod 46 Molybdenum wire

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI // C04B 35/64 C04B 35/64 A (56) References JP-A-4-39385 (JP, A) JP-A-57- 11824 (JP, A) JP-A-58-13688 (JP, A) JP-A-57-74382 (JP, A) JP-A-2-1555984 (JP, A) JP-A-1-184389 (JP, A)

Claims (3)

(57) [Claims] 1. A phosphor raw material powder comprising a sulfide or selenide of an alkaline earth metal and an activator, or a flux thereof and a flux is compression-molded, and then the compression-molded fluorescent material is produced.
A method for producing an infrared stimulable phosphor, comprising subjecting a raw material powder to heat treatment without contacting a container or a furnace core tube . 2. An alkaline earth metal sulfide or selenium.
Consisting of fluoride and activator, or these and flux
After compression molding the raw material powder,
Heat treatment of body material powder without contact with container or furnace core tube
Infrared stimulable phosphor produced by applying 3. An infrared stimulable phosphor according to claim 2,
And at least one of the sealing layers is
Using infrared stimulable phosphor characterized by being transparent
Infrared-visible conversion element.