JPH0584892U - Watch case structure - Google Patents

Abstract

(57) [Abstract] [Purpose] It is a convenience that a portable watch has a bremsstrahlung that has a harmful effect on the human body and is generated by the collision of β rays of Pm147 in a portable watch having a luminous paint containing a radioisotope. Attenuating the effect of radiation on the wrist that is always wearing the watch, without sacrificing its small size and thinness,
The purpose is to shield. [Structure] A lead material (Pb) having a bremsstrahlung shielding effect about 8 to 13 times greater than that of iron is arranged inside a watch case.
The location is the inner surface of the back cover, the lower surface of the dial, and the inner side of the case side body.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a watch case structure including a dial, hands, dial rings and the like for applying a luminous paint containing a radioisotope.

[0002]

[Prior Art]

 A conventional watch case structure coated with a luminous paint containing a radioactive isotope has a structure as shown in FIG. That is, in FIG. 2, 1 is a watch case, 2 is a back cover, 3 is a glass, 4 is a dial, 5 is a needle, and 4a and 5a are a dial and a needle coated with a luminous paint containing a radioactive isotope. There is. Since the luminous paint containing radioisotope has self-luminous property, it is convenient to apply it on the upper surface of the needle and dial so that it can be read even when the position of the needle or dial is dark. However, the luminous paint is composed of a radioisotope, a luminescent substrate ZnS, and a binder binder, and the radioisotope emits at least a minute harmful radiation to the human body.

[0003]

[Problems to be solved by the device]

 The radioactive isotopes used in the luminescent paint include promethium 147 (Pm147) and tritium (H3), but each element alone produces β rays. The β ray itself has a short range of 30 cm or less in the air, and can stop even with a plastic material of 1 mm, but when β ray collides with other elements (Zn of the light emitting substrate), bremsstrahlung is generated. Bremsstrahlung radiation is highly transparent, and with the conventional structure, bremsstrahlung radiation goes out. For example, in FIG. 2, the amount of radioactivity of the dial and the needle is Pm147, which is 3. 7MBq megabecquerel (= 100μCi micro key Lee), dial 4 plate thickness 0.5mm, back cover 2 plate thickness 0.5mm, mechanical body 6 thickness 3mm, all materials are assumed to be iron, dial plate top surface The distance from the outer surface of the back lid to the outer surface of the back lid is set to 5 mm, and it is calculated as follows by the "Radio ISOTOPES" "Brake Radiation Shielding Calculation Method" issued in September 1990.

Assumption 1. The target of Pm147 is Zn = 20, which has a large atomic number.

2. The self-absorption correction of the luminous paint is about 0.16.

3. Half of 3.7MBq and 1.85MBq affect the back cover direction.

[0007] 4. The material having the shielding effect is iron and has a total thickness of 4 mm.

5. The distance from the radiation source is 5 mm.

From the above, the 1 cm dose equivalent rate on the outer surface of the back cover is 0.047 μSv (microsievert) per hour. This amount is about 0.4 mSv (Millisievert) per year. This amount does not have an immediate adverse effect on the human body, but has a problem that it affects the human body (particularly the arm part) even if it is minute.

Therefore, an object of the present invention is to solve such a problem, and an object thereof is to provide a watch case structure that reduces the influence of bremsstrahlung.

[0011]

[Means for Solving the Problems]

 The watch case structure of the present invention is a mobile watch composed of a dial, hands, a dial ring, etc. to which a luminous paint containing a radioisotope is applied, and shields bremsstrahlung such as lead between the mobile watch case and the machine body. It is characterized by arranging highly effective materials.

[0012]

【Example】

 FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention, in which 11 is a watch case, 12 is a back cover, 13 is glass, 14 is a dial, 15 is a needle, and 16 is a mechanical body. Nos. 4a and 15a are applied with a luminous paint containing a radioactive isotope on the dial and the needle. Reference numeral 17 is a shielding plate made of lead, which is adhered to the inner surface of the back lid or is fixed to the inner surface of the back lid by a protrusion from the lower part of the machine body 16. Here, by inserting the shielding plate 17 made of lead material with the same dimension setting as in FIG. 2, the shielding effect is obtained as follows.

[0013]

[Table 1]

For example, the 1 cm dose equivalent rate on the outer surface of the back lid calculated in the conventional example of FIG. 2 can be set as follows by the shielding effect by placing the lead plate on the inner surface of the back lid.

[0015]

[Table 2]

In order to obtain the same shielding effect with iron or stainless steel, a thickness of about 8 to 13 times is required, and the thickness of the watch case becomes thick and heavy.

FIG. 3 shows another embodiment of the present invention. Reference numeral 27 denotes a plate made of a lead material arranged on the lower surface of the dial plate, and the same effect as in FIG. 1 can be obtained.

FIG. 4 shows another embodiment of the present invention. Reference numeral 37 is a tubular member made of lead material, and encloses the outer periphery of the mechanical body 36 in a tubular shape. This is effective in blocking bremsstrahlung rays leaking from the side surface of the case 31.

[0019]

[Effect of the device]

 As described above, according to the present invention, in a mobile timepiece including a dial, hands, a dial ring, etc., to which a luminous paint containing a radioisotope is applied, a bremsstrahlung such as lead between the mobile timepiece and the machine body By arranging a material having a high shielding effect, it is possible to obtain the same shielding effect against radiation that adversely affects the human body with a plate thickness of about 8 to 13 times lower than that of iron material. Moreover, the thickness of the lead plate is 0.1 mm, and it can be attenuated to about 1/10 of that without the lead plate. Thus, the practical effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a watch case structure of the present invention.

FIG. 2 is a sectional view of a main part showing a conventional watch case structure.

FIG. 3 is a sectional view of a main part showing another embodiment of the watch case structure of the present invention.

FIG. 4 is a sectional view of a main part showing another embodiment of the watch case structure according to the present invention.

[Explanation of symbols]

 11 Watch case 12 Back lid 13 Glass 14 Dial 15 Needle 16 Mechanical body 17 Shield 14a Needle luminescent paint containing radioactive isotope 15b Dial luminescent paint containing radioactive isotope

Claims (4)

[Scope of utility model registration request] 1. A mobile timepiece including a dial, hands, dial ring, etc. coated with a luminous paint containing a radioisotope, and a shielding effect of bremsstrahlung such as lead between a mobile timepiece case and a machine body. A watch case structure characterized by placing high-quality materials. 2. The watch case structure according to claim 1, wherein the lead plate is disposed on the inner surface of the back cover. 3. The lead plate is arranged on the lower surface of the dial plate.
Watch case structure described in. 4. The watch case structure according to claim 1, wherein the lead plate is arranged radially inside the case body.