JPS5950981B2 - radiation sensitive photoconductive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to components sensitive to electromagnetic radiation.

Conventionally, various methods are known for recording and displaying using X-rays.

For example, a silver halide photosensitive layer, a coating layer of fluorescent pigment, an electrophotographic photosensitive layer of selenium, cadmium sulfide, zinc oxide, etc.
Recently, ionography that utilizes the ionization phenomenon of gases, or display boards that combine an electroluminescent layer and the above-mentioned electrophotographic photosensitive layer, have been developed for medical and industrial purposes. On the other hand, these X-ray information processing materials and methods also include the following problems.

That is, silver halide photosensitive layers and ionography, which have relatively high sensitivity, require complicated processing steps, and resource depletion has become a problem, especially as demand has increased in recent years. Furthermore, electrophotographic photosensitive layers and fluorescent light-emitting layers that allow images to be obtained through simple steps have low sensitivity, which poses a problem in terms of user safety.

The main object of the present invention is to provide a highly sensitive receptor that exhibits remarkable electrical conductivity when exposed to various types of radiation including X-rays.

″ The present invention relates to a compound represented by the following general formula (hereinafter,
A radiation-sensitive photoconductive material characterized in that it comprises a layer having a compound (simply referred to as a compound).

However, M is a heavy metal element selected from Hg, Ti, Bi and Sb, X is an element selected from Group Vlb elements and iodine elements, l, m and n are positive integers, and 1= There is a relationship between m and n.

The compound employed in the present invention has a sensitivity much higher than that of zinc oxide, cadmium sulfide, and cadmium selenide, which are conventionally used as X-ray sensitive θ receptors.

The intended objective of the invention is achieved by this high sensitivity. The compounds according to the invention are specific heavy metal salt compounds,
Heavy metal elements M include water 15 silver, thallium, bismuth,
Preferable examples include heavy metal elements such as antimony. In addition, other elements X that make salt include oxygen, sulfur,
Suitable examples include Group Vlb elements such as selenium and tellurium, and iodine. Hg as some representative examples of compounds according to the invention.

O, Tl. O. , Bi. O. , Sb. O. ,HgS,H
g2S, TI2S3, Sb2S5, Bi2S3, Sb2
S3,SB2Se3,HgSe,Hg2I,Hgl,T
lI3, BiI3, SbI5 and Sbl. etc. Further, it goes without saying that there is no problem in the present invention with adding a small amount of other impurity elements to the compound or subjecting it to heat treatment for the purpose of modifying the electrical properties, and this is, of course, included in the present invention. Application of the compounds usually occurs in two forms.

One is a relatively non-transparent layer made by dispersing fine powder of a compound in a binder, and the other is a relatively transparent thin film manufactured by vapor deposition, sputtering, etc. It is. The binding material is usually preferably a material with higher electrical insulation than a compound. In general, organic binders include
There are resins that have high electrical insulation and excellent mechanical properties. For example, preferred binder resins include polystyrene, polymethyl methacrylate, poly-9-vininolecanolebazole, polyethylene terephthalate, ethyl cellulose,
Examples include nitrocellulose, polyvinyl chloride, and various latexes.

The electrical resistance of such a binder resin is 10°Ω.cm or more, and it can be said to be appropriate, especially in the present invention when a binder is used. The most common method for manufacturing a layer containing a compound is to add fine powder of the compound to a binder solution and disperse it by means such as ball milling or ultrasonic stirring, or to add it to a molten binder. A fine powder is kneaded into the material using a roll mill or the like, and then coated on the target substrate to form a layer. Similar to organic binders, it is also effective to use inorganic binders that have excellent electrical insulation properties.
Some typical examples of such inorganic binders include Si
Glass-forming oxides such as O2, Al2O3, B2O3, and mixtures thereof. A suitable amount of a compound can be added to this glass-forming oxide and formed into a layer by, for example, melting or sintering to a desired size.
Depending on the properties of the binder, the amount of compound particles added can be divided into two areas. In other words, in layers where charge carriers (electrons or holes) generated by radiation absorption cannot be transported through the binder, it is desirable that adjacent compound particles come into contact with each other. For 100 parts by volume of the binder, 70 to 500 parts by volume of the compound particles are required, and in consideration of film properties, sensitivity, etc., preferably 10 parts by volume.
0 to 300 parts by volume are particularly suitable. On the other hand, poly-9
- Photoconductive binding materials such as vinylcarbazole, halogenated poly-9-vinylcarbazole, polyvinylanthracene, polyacenaphthylene, polyvinylacridine, and α-alkyl acrylic acid amide polymers have the property of transporting charge carriers. In such systems, the amount of compound particles can be reduced. For example, even with 10 to 100 parts by volume of compound particles for 100 parts by volume of the binder, a layer having appropriate sensitivity can be obtained. It is also possible to use the compound itself as a thin film.

To produce thin films, methods such as vapor deposition are used on well-cleaned substrates. Vapor deposition is performed by a well-known general vapor deposition method. Alternatively, sputtering or CVD (chemical paper deposition) may be used. However, this does not apply if the compound is decomposed. A susceptor having a layer containing a compound thus formed is used as a detector for various types of radiation, a non-contact switch, an indicator, an image forming device, etc.

These uses are, of course, based on radiation-induced changes in the electrical properties of the layer containing the compound, such as changes in resistance. For example, it is used as a detector by detecting a change in resistance (increase in current) due to radiation in a layer containing a compound, and it is used as a non-contact switch by turning 0n-0FF due to a change in resistance due to radiation. It is used as an indicator by converting changes into changes in optical properties (absorption rate, reflectance, refractive index, color development, luminescence, etc.). It is also used as an electrophotographic photoreceptor in electrophotographic techniques. One example of these applications is a laminate of a layer containing a compound and an electrically variable light transmittance material layer. A light-transmitting substance is a substance whose optical transparency changes depending on an electric current, voltage, or electric field. Examples of substances whose optical transparency changes depending on an electric current include dynamic scattering mode liquid crystal, electrochromic titanium oxide,
These include molybdenum oxide, niobium oxide, tungsten oxide, viologen solution, etc. In addition, materials whose light transmittance changes depending on voltage include ceramic materials such as lithium niobate and lithium zirconate titanate added with phosphorus;
Alternatively, an electroluminescent phosphorus compound may be used. It goes without saying that such a substance whose optical properties change electrically may be used as a laminate with a layer containing a compound, or may be included in a layer containing a compound. Nor. In this case, as will be explained in the drawings below, it is not necessary to have a laminated structure of a layer containing a compound and a layer whose optical properties change electrically, and only one layer is sufficient. FIG. 1 shows an example of a visualization display device comprising a layer containing a substance and a compound whose optical properties change electrically. Reference numeral 10 indicates a display panel, and its configuration is so-called Nesa glass, in which a transparent electrode 12 made of tin oxide, indium oxide, etc. is provided on a transparent substrate 11 made of glass, etc., and a variable light transmittance material is placed on top of the transparent electrode 12 made of tin oxide, indium oxide, etc. Layer 13 is laminated.

A layer 14 with a compound is then provided. A thin layer electrode 15 made of aluminum, beryllium, or the like, which is highly transparent to X-rays, is attached to the X-ray irradiation surface side. When the display panel is irradiated with X-rays 17 from the electrode 15 side while applying an electric field between the electrodes 12 and 15 using the power source 16, a change in light transmittance occurs in the layer 13, and a change occurs along the X-ray pattern. A visible image can be observed from the substrate side. Also, if necessary,
It is preferable to provide a white reflective layer on the back side of the variable light transmittance material layer, that is, between layers 13 and 14.

Titanium oxide and magnesium oxide are particularly suitable for the reflective layer. Furthermore, since the layer 14 has photoconductivity in the visible light region, high sensitivity can be achieved by providing a fluorescent pigment layer adjacent to the layer 14. In the examples shown below, electromic tungsten oxide is used as the light transmittance variable material, but it goes without saying that the present invention is not limited to this. In addition, when tungsten oxide is energized, it produces blue compounds with different oxidation valences and is visualized, but this blue compound persists until a reverse electric field is applied, so it can be visualized as in medical X-ray viewing.
When observing a dynamic object, it is advantageous to use images fixed at a certain time.

Note that the substrate may be omitted in FIG. 1. When radiation irradiation is accompanied by electrical conversion, many other electrochromic or electroluminescent materials can be used. Next, the present invention will be explained with reference to Examples.

Quantities in Examples indicate parts by weight unless otherwise specified.

Example 1 20 parts of each of the following compounds were added to 100 parts of an 8% toluene solution of polystyrene, and dispersion in a ball mill was performed for 24 hours to prepare a number of dispersions corresponding to the number of types of compounds.

The compounds used were Hg2O, Bi2O3, HgO, Hg
S, Hg2S, Sb2S3, Bi2S3, HgSe, H
13 of g2l, HgI, Tll3, BiI3, SbI3
It is a kind.

From each of these dispersions, a radiation sensitive material for a display panel having the structure shown in FIG. 1 was prepared. That is, in FIG. 1, 10c
An electrochromic layer 13 was provided on Nesaglass transparent electrodes 11 and 12 of m×10 cm.

The electrothalomic layer consists of two layers: first, zirconium oxide is deposited on Nesa glass to a thickness of 0.3μ, and then an electrochromic material, tungsten oxide, is deposited on top of it to a thickness of 0.6μ.
The coloring layer was formed by vapor deposition to a thickness of . Next, although not shown in FIG. 1, a solution of titanium oxide dispersed in polystyrene was applied as a reflective layer between layer 13 and layer 14 to a dry film thickness of 1 μm.
A coating film was formed on the surface.

Next, a dispersion of the above compound is applied on top of this to form a layer 14.
was formed. The thickness of layer 14 is 5μ. Finally, a display panel was fabricated by attaching aluminum with a thickness of 2 μm as the electrode 15 on the radiation side. A voltage of 5 was applied to this panel between the transparent electrode and the negative electrode on the radiation exposure side.

The current value at this time was 1 μA or less. Next, when a projection pattern was irradiated with an X-ray source at a tube voltage of 50 K and a tube current of S4 mA (7), a blue visible pattern was obtained. Images were obtained with an exposure time of about 15 to 20 seconds, although the degree of exposure varied depending on the compound used. This pattern persisted until a reverse electric field was applied. Furthermore, the current flowing through the display panel during X-ray irradiation was 3 mA or more. Example 2 A display panel having the same structure as in Example 1 was prepared by using poly-9-vinylcarbazole instead of polystyrene as a binder in the layer containing the compound prepared in Example 1.

The layer containing the compound was prepared by adding 12 parts of the compound shown in the example to 100 parts of a 6% chlorobenzene solution of poly-9-vinylcarbazole, dispersing it in a ball mill, and obtaining a dry film thickness of 4.
It is applied so that it becomes μ.

Using the display panel having this configuration, a blue image was obtained in the same manner as in Example 1.

Example 3 In the display panel having the structure of Example 1, Sb is a compound particularly sensitive to visible light.

S3, Hg2I, Hgl, Bil. A fluorescent light-emitting layer was provided for the purpose of further sensitization in the display panel using the fluorescent light emitting layer. The fluorescent light-emitting layer was prepared by dispersing a fluorescent pigment ZnS2O part in 40 parts of a 15% alcohol solution of a conductive polymer, and then providing the layer with a thickness of 10 μm between the layer containing the compound and the radiation-exposed electrode. With this display panel, an image of an X-ray projection pattern was obtained in 5 to 10 seconds under the exposure conditions of Example 1. Example 4 Tungsten oxide was deposited to a thickness of 0.6μ as an electrochromic layer on a transparent electrode (Nesa Glass).

A layer of magnesium oxide was then applied as a reflective layer to a thickness of approximately 3 microns. Magnesium oxide is obtained by burning a magnesium ribbon in the air and depositing it on the coloring layer. Next, from above this reflective layer, Sb, S is added as a layer containing a compound.

was deposited to a thickness of 10μ. Furthermore, a conductive polymer layer in which the fluorescent pigment shown in Example 3 was dispersed was applied, and a thin layer of beryllium was adhered to the top to form an electrode, thereby producing a display panel. In a display panel with this configuration, the transparent electrode side is exactly 5
An electric field of V was applied between the beryllium electrode and the X-rays were irradiated from the beryllium electrode side.

The X-ray source was the same as that used in Example 1. A blue projection pattern was obtained in about 20 seconds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an X-ray display panel showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 10... Display panel, 11... Substrate, 12... Transparent electrode, 13... Light transmittance variable material layer, 14... Layer containing a compound, 15... Electrode, 16... power supply, 1
7...X-ray.

Claims (1)

[Scope of Claims] 1. A radiation-sensitive photoconductive material comprising a layer containing a compound represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, M is a heavy metal element selected from Hg, Tl, Bi and Sb, X is an element selected from Group VIb elements and iodine elements, k, l, m and n is a positive integer and k
There is a relationship l=mn. 2. A radiation-sensitive photoconductive material comprising a layer containing the compound according to claim 1 and a substance whose optical properties electrically change.