JPS6230376Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube device, and an object of the present invention is to provide a cathode ray tube device having an X-ray shielding structure that has a simple structure and can reliably prevent leakage of X-rays from the cathode ray tube.

As is well known, inside a cathode ray tube, X-rays are generated from a phosphor due to the action of electron beams.

The power of the CRT in conventional small television receivers is low, and the
The wire rarely leaks to the outside.

However, recently introduced large-screen projection color television receivers have greater power than conventional small-sized television receivers. However, conventional large-screen projection color television receivers have one cathode ray tube, as shown in Figure 1.
1, a lens 12 provided to face the front surface of a cathode ray tube 11, and a screen 13 for projecting images.
No consideration was given to line leakage. Of course, even in conventional cathode ray tubes, elements that have a strong X-ray shielding effect are added to the glass that makes up the tube.
For example, some products have added lead or other substances to reduce leakage of X-rays, but this method cannot prevent leakage of X-rays from large-screen cathode ray tubes with high power.
Using the same concept as this conventional X-ray shielding method, we investigated the material and shape of large cathode ray tubes, but problems such as destruction of the tube due to the large amount of heat generated inside the tube and There is a problem that increasing the amount of metal elements such as lead, which have a strong hazing effect, causes the glass to become colored, and from the standpoint of the safety and performance of cathode ray tubes, it is extremely difficult to easily change the material of conventional cathode ray tubes. be.

Therefore, the inventors conducted a detailed investigation into the distribution and amount of leaked X-rays from the cathode ray tube of the large screen. As a result, as shown in FIG. 2, the leaked X-rays were X-rays A and A' from the side glass faces and X-rays B from the front glass face.

The amount of leaked X-rays at this time is 100 mR/H for X-rays A and 100 mR/H for X-rays B from the side glass face when the cathode ray tube is used under normal conditions.
The leakage rate of X-ray B from the front glass surface was 3 mR/H.
It should be noted that the difference in the amount of X-rays at the side glass faces A and A' is due to the difference in the glass material and the distance from the X-ray source.

The amount of leaked X-rays from the cathode ray tubes used in such large screens far exceeded the legal limit of 0.5 mR/H and was extremely dangerous.

The cathode ray tube device according to the present invention is intended to eliminate the above-mentioned drawbacks of the conventional art, and embodiments thereof will be described below with reference to the drawings.

FIG. 3 shows an X-ray attenuation curve for iron, which is one of the X-ray resistant materials on which the present invention is based. Note that the anode voltage (peak value) was 36 KV. In the figure, the horizontal axis shows the thickness of the X-ray resistant material, and the vertical axis shows the relative value of the amount of X-ray attenuation on a logarithmic scale. The value of the anode voltage mentioned above is higher than the maximum design high voltage of cathode ray tubes for large-screen color television receivers, and from the viewpoint of safety during use, we conducted the study at a voltage that is sufficiently higher than the normal operating voltage. . As a result, it was found that a steel plate with a thickness of 1 mm can attenuate the amount of leaked X-rays by about 1/27, and a plate with a thickness of 2 mm can attenuate the amount of leaked X-rays by about 1/2900.

Next, one embodiment of the present invention will be described using FIG. 4. FIG. 4a is a side view, and FIG. 4b is a sectional view of the main part.

In the figure, 1 is a cathode ray tube, and 2 is an X-ray tube for suppressing X-rays from the side of the cathode ray tube 1.
This is a radiation shield body made of a metal with a large X-ray absorption coefficient, such as iron, and is used to suppress X-rays leaking from the portion from the deflection coil 3 to the Brown front surface. Reference numeral 4 denotes a mounting band for attaching and fixing the cathode ray tube 1 to the shield case 5. It is made of a metal such as iron that has a high X-ray absorption coefficient, and in addition to its original function, it also prevents leakage as shown in Figure 2. In order to suppress X-rays A from the side of the cathode ray tube, which are very strong X-rays, it is connected to the shield body 2 with a rivet 6 and is not removable. That is, the structure is such that the leaked X-rays A can be completely suppressed by the shield body 2 and the attachment band 4. The shield case 5 is a dark box for blocking light from the outside, and is hollow. The material is a metal with a large X-ray absorption coefficient, such as iron, and has the additional role of preventing X-rays B' from leaking to the outside from the front side of the cathode ray tube. In addition,
The shield case 5 is connected to the shield body 2, the cathode ray tube mounting band 4, and a non-removable rivet 6. Therefore, it is possible to prevent an X-ray leak accident caused by a general user disassembling the shield body 2, band 4, etc. The screw 7 is for reinforcing the rivet 6. Reference numeral 8 denotes a lens system, which is attached to the shield case 5 and is used to magnify the image from the cathode ray tube 1 and project it onto the screen. The data will not be leaked to the outside.

As described above, the configuration of the present invention is such that the first shield body that covers the side surface of the cathode ray tube and the second shield body provided on the front surface of the cathode ray tube are fixed with a non-removable rivet via the cathode ray tube mounting band. and a lens is added to the second shield body.

Specifically, as a result of measuring the amount of leaked X-rays of a prototype made of iron with a thickness of 1 mm for the shield body, shield case, and cathode ray tube mounting band,
At any point, it is less than 0.2mR/H,
This was far below the legal limit of 0.5mR/H.

In this way, the present invention has a simple configuration in which the shield body on the side of the CRT is connected to the shield case via the CRT mounting band, which is a conventional component, and almost completely suppresses X-rays from the CRT and prevents them from leaking outside. can be effectively suppressed.

[Brief explanation of the drawing]

Figure 1 is a side view of a conventional cathode ray tube, Figure 2 is a diagram showing the locations of leakage X-rays from a conventional cathode ray tube,
Fig. 3 is a diagram showing an example of an X-ray attenuation curve of an It is a sectional view of the main part. 1... Braun tube, 2... X-ray shield, 3
... Deflection coil, 4 ... Mounting band, 5 ... Shield case, 6 ... Rivet, 7 ... Screw, 8
...Lens system.

Claims (1)

[Claims for Utility Model Registration] (1) The first X covering the side part of the cathode ray tube
a second hollow X-ray shield provided on the front surface of the cathode ray tube; a mounting band for fixing the first and second X-ray shields to the cathode ray tube; and a second X-ray shield. A cathode ray tube device comprising: a lens attached to the X-ray shield body so as to face the front surface of the cathode ray tube. (2) Utility model registration claim 1, characterized in that the first X-ray shield body and the second X-ray shield body are connected to the mounting band by a non-removable fixing means. The cathode ray tube device described in Section 1.