JPS5830576B2 - Latent image receiving film for electron radiation image formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to latent image receiving films for electron radiation imaging.

Conventionally, radiation images (hereinafter also referred to as X-rays) using highly insulating liquids that absorb radiation such as
The method for creating line images is described in Japanese Patent Application Laid-open No. 50-87793,
JP-A-50-125694, JP-A-50-13717
No. 6 (US Pat. No. 3,873,833).

In other words, as shown in Figure 1, it is a highly insulating material that generates electrons and positive polarity ions or positive and negative polarity ions by absorbing X-rays between a pair of electrodes 1 and 2 arranged almost parallel to each other with a gap between them. filled with X-ray absorbing liquid 3,
An insulating image receiving sheet 4 is placed in this X-ray absorbing liquid 3 in contact with one of the electrodes, and while a voltage is applied between the electrodes 1 and 2, X-rays are irradiated by the X-ray source 5 to expose the subject 6. This is a method in which the transmitted X-rays are exposed to the X-ray absorbing liquid 3. According to this method, the insulating X-ray absorbing liquid 3 is
is ionized, and the generated electrons and positive polarity ions or positive and negative polarity ions move to the corresponding electrode 1°2 side,
An electrostatic latent image is formed on the image receiving sheet 4.

The obtained electrostatic latent image is developed into a visible image by a known electrophotographic method.

In this method, most of the image receiving channel 4 is exposed to the X-ray absorbing liquid 3.
Since the X-ray absorbing liquid 3 is operated by being immersed in the liquid, it is necessary that the resistance of the X-ray absorbing liquid 3 is sufficiently high in order to form an electrostatic latent image and retain the latent image. In order to maintain this, it is necessary for the X-ray absorbing liquid 3 to have a volume resistivity of 10'', Q-cm or more, so a low-resistance X-ray absorbing liquid cannot be used.

Additionally, in order to increase sensitivity, it is desirable to use an X-ray absorbing liquid with strong X-ray absorption, but most X-ray absorbing liquids that exhibit strong X-ray absorption are unstable residual solvents that decompose due to light or static. When the image receiving sheet 4 is immersed in the X-ray absorbing liquid 3, impurities soluble in the X-ray absorbing liquid 3 adhering to the image receiving sheet 4 may dissolve and cause abnormal discharge. Resulting in.

In addition, in order to increase the absorption efficiency of X-rays, C is added to the X-ray absorbing liquid 3.
When solids such as Br4°CHI3 are dissolved, when the image receiving sheet 4 is taken out, the liquid adhering to the surface dries and these solids precipitate, resulting in low resistance and disturbing the electrostatic latent image.

Furthermore, since the X-ray absorbing liquid 3 may come into contact with the outside air, it may receive various types of contamination from the outside air and become unstable.

Further, since the image receiving sheet 4 is immersed in the X-ray absorbing liquid 3, impurities are mixed in therein.

Further, since the image receiving sheet 4 is in a wet state, it is necessary to dry it, and at that time, the latent image may disappear or the X-ray absorbing liquid 3 may be mixed into the developer and deteriorate the developer.

Furthermore, the amount of X-ray absorbing liquid 3 decreases when the image receiving sheet 4 is taken in and out, which increases the amount used and poses a safety problem. There is.

Therefore, as shown in FIG. 2, the present inventor previously arranged an electrode r and an insulating film 8 in parallel using an insulating spacer 9, and filled the gap with an X-ray absorbing liquid 10. An insulating film 11 is placed on the outer surface of the insulating film 8 of chamber A. The back electrode 12 with high X-ray transparency is stacked, and while a voltage is applied between both electrodes t and 12, X-rays are irradiated from the front of the subject 13 placed on the back electrode 12 side, and then the insulating film 11 is placed in the chamber. We have proposed an electron radiation image forming method characterized by forming an electrostatic latent image on the insulating film 11 by peeling it off from A.

The electron radiation image forming method configured in this way is similar to the conventional X
It has the following advantages over methods using line-absorbing liquids.

First of all, the X-ray absorbing liquid 10 is completely sealed and never comes into contact with the outside air, so it does not receive various contamination from the outside air, and the X-ray absorbing liquid 10 is always stable. There is.

Second, since the latent image receiving insulating film 11 is not immersed in the X-ray absorbing liquid 10, the contamination of impurities, which has been a very serious problem in the conventional method, can be solved.

Thirdly, the latent image receiving insulating film 11 does not come into contact with the X-ray absorbing liquid 10, and the insulating film 11 can be separated from the chamber A at any time after X-ray irradiation. Low resistance X-ray absorbing liquids, which cannot be used with conventional methods, can be used.

Fourth, since the electrostatic latent image formation is completely dry, in the conventional method, the latent image disappears while the X-ray absorbing liquid 10 is dried, or the X-ray absorbing liquid 10 is mixed into the developer. This will not cause deterioration of the developer.

Fifth, since the X-ray absorbing liquid 10, which is often a harmful substance, is sealed, the amount used can be minimized, and safety issues can also be solved.

However, with this formation method, the insulating film 11 is peeled from the chamber A and a latent image is formed on the insulating film 11 by peeling discharge, so there is a time difference between the X-ray irradiation and the formation of the latent image. This method has a problem in that a latent image corresponding to the subject 13 cannot be accurately formed on the insulating film 11.

The present invention was made in view of the above circumstances, and its purpose is to provide a latent image receiving film for electron radiation image formation that can accurately form a latent image corresponding to a subject during X-ray irradiation. be.

The present invention will be described in detail below with reference to FIG. 3 and subsequent figures.

FIG. 3 is a cross-sectional view of the latent image receiving film 15 according to the present invention, which has a structure in which a void 15b is formed within an insulating main body 15a.

Next, a method of forming an X-ray image using this latent image receiving film 15 will be explained.

As shown in FIG. 4, a back electrode 12 having high X-ray transparency is placed on the latent image receiving film 5, and this latent image receiving film 15 is placed on the chamber A.

The chamber A is the same as the chamber A shown in FIG. The X-ray absorbing liquid 10 is sealed in the gap to prevent contact with the outside.

Here, if there are air bubbles inside the chamber A, it will cause abnormal discharge, so special care must be taken to ensure that no air bubbles remain when filling the X-ray absorbing liquid 10.

The insulating film 8 should be made of a material that is sufficiently thin and has guaranteed mechanical strength, such as a polyester film with an original thickness of 25 μm, to prevent a decrease in resolution and to reduce damage to the chamber A. desirable.

For the electrode γ, a material that will not be altered by the X-ray absorbing liquid 8 should be selected, such as a carbon plate, a metal plate coated with gelatin that mixes carbon, or a metal plate covered with a thin plastic film. .

The spacer 9 is made of a plate material having high insulation properties and a uniform thickness, such as a Delrin plate having a thickness of about 1 inch.

The enclosed X-ray absorbing liquid 10 is a liquid material that absorbs X-rays and emits electrons when irradiated with X-rays, and has a volume resistivity of 1012 to 2-am or more when not excited by X-rays. is preferably used.

For example, carbon tetrabromide is added to a liquid of carbon tetrachloride at a weight ratio of 50%.
It is a liquid made by dissolving the liquid.

When enclosing the X-ray absorbing liquid 10, sufficient care must be taken not only to prevent the presence of the above-mentioned air bubbles, but also to prevent contamination of impurities such as loaded particles and conductive particles.

To form an X-ray image, a voltage is applied between the electrode γ and the back electrode 12, and at the same time, the subject 13 placed on the back electrode 12 side is irradiated with X-rays from the front X-ray source 14.

Here, the value of the applied voltage is such that the voids 15b inside the latent image receiving film 15 can be discharged in the X-ray irradiated area, and the non-X-ray irradiated area is slightly lower than the discharge start limit value.

In this way, ion pairs are generated in the X-ray absorbing liquid 10 according to the amount of incident X-rays, and each ion moves toward the electrode r and the insulating film 8 due to the electric field within the X-ray absorbing liquid 10.

For example, when a positive voltage is applied to the electrode γ, positive ions generated by X-rays move to the inner surface of the insulating film 8.

For this reason, the electric field strength in the gap 15b inside the latent image receiving film 15 increases, and discharge becomes possible in the gap 15b, so that the latent image corresponding to the subject 13 is generated by the gap discharge inside the latent image receiving film 15. It is formed in the internal cavity 15b during X-ray irradiation.

Thereafter, the latent image receiving film 15 is taken out and the latent image formed in the void 15b inside the film 15 can be visualized by developing it by a known electrophotographic developing process.

For example, when a positive voltage is applied to the electrode t, the surface potential of the latent image receiving film 15 shows a more negative potential in the X-ray irradiated area than in the non-X-ray irradiated area.

That is, the latent image receiving film 1 when the back electrode 12 is grounded.
The more X-ray energy absorbed by the X-ray absorbing liquid 10, the more negative the surface potential of the surface 5 becomes.

When this is developed with positive polarity toner, the positive polarity toner adheres to the surface of the latent image receiving film 15 in the area irradiated with X-rays, making the latent image visible.

As described above, a latent image corresponding to the subject 13 can be formed in the gap 15b inside the latent image receiving film 15 during X-ray irradiation.

Here, the void 1 existing inside the latent image receiving film 15 is
The length t of 5b is preferably 6 μm or more and equivalent to 10 to 15 μm in the thickness direction of the film.

This is because it is desired to increase the resolution and the electric field strength within the X-ray absorbing liquid 10 during imaging in terms of ion collection efficiency.

That is, if the individual gap length t is too long, the electric field strength within the X-ray absorbing liquid 10 cannot be increased.

Further, the gap length t does not necessarily have to be constant in each gap 15b, but only needs to be uniform in terms of volume distribution. For example, the gap length t may be equivalent to about 10 μm to 15 μm, as described above.

Further, the higher the porosity (ratio of void volume to total volume), the more effectively the latent image inside the latent image receiving film 15 can be developed during development.

Further, the material of the latent image receiving film 15 must be insulating in order to prevent the latent image inside the film from decreasing after photographing and before development.

Note that the surface of the latent image receiving film 15 facing the insulating film 8 is required to be sufficiently smooth, and
It is necessary to set the gap length t' between the insulating film 8 and the latent image receiving film 15 to a few microns or less to prevent discharge from occurring in this gap. This gap length t' may be eliminated by impregnating a small amount of 65 cs of silicone oil or the like between the latent image receiving film 15 and the insulating film 8.

Next, a specific example of the latent image receiving film 15 will be described.

[Example 1] Polystyrene 50 gr and 2,2'-azobis(2
, 4-dimethylvaleronitrile) are dissolved in 50 gr of toluene.

Later, this is placed in an aqueous gelatin solution and emulsified to form a powder with a microparticle size (several μm).

This powder was applied onto a smooth polyester film having a thickness of 25 μm and heated and foamed to form a latent image receiving film 15.

The thickness of this film is approximately 80 μm, and the gap length t is approximately 10
μ average.

Using this latent image receiving film 15, the electrode r and the back electrode 1 are
Apply a voltage of 15KV between 2 and 75KV P,
100 m AX 0.2Secf) X-rays were irradiated and a good image was obtained when the A1 difference was photographed at a position approximately 1 m from the X-ray source 14.

(Example 2) 30 gr of acrylic resin and foaming agent Azobis.
9 gr of iso-butyronitrile and 40 g of toluene
Dissolve in r.

This was applied onto a smooth polyester film having a thickness of 25 μm, and heated and foamed to obtain a latent image receiving film 15.

The average void length t inside this latent image receiving film 15 is approximately 1
The thickness was approximately 75 μm, and the shape and size of the voids were uniform in terms of volume distribution.

Using this latent image receiving film 15, the electrode 1 and the back electrode 1 are
Apply a voltage of ■ to 11 between 2 and the X-ray tube voltage is 75KVP.
, X-rays with a tube current of 100 mA were irradiated for 0.2 se@, and a good image was obtained when A [gradation difference] was photographed at a position approximately 1 m from the X-ray source.

Since the present invention is configured as described above, a latent image corresponding to the subject can be accurately formed during X-ray irradiation.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional example, Fig. 2 is an explanatory diagram of an improved method, Fig. 3 is a sectional view showing an embodiment of the present invention, and Fig. 4 is a diagram showing a method using a latent image receiving film according to the present invention. FIG. 2 is an explanatory diagram of a method of forming an X-ray image using the same method. 15 is a latent image receiving film; 15a is a main body; and 15b is a gap.

Claims (1)

[Claims] 1. A latent image receiving film for forming an electron radiation image, characterized in that a void 15b is formed in an insulating main body 15a.