JPH066647A - Image pickup device usable under high pressure - Google Patents

Abstract

PURPOSE:To make the size small and the weight light and to eliminate distortion of an image by putting in an optical system and a camera sending a video signal into an enclosed vessel having a window and a liquid pressure equalizing valve and filling a liquid not impregnating the built-in equipments. CONSTITUTION:This device is provided with an enclosing container case 11 whose thickness is thinner than the thickness of a conventional pressure-resistant case, a window 12, a bellows 13 fitted to the container case 11, the image pickup device 14 comprising an optical system section 141 and a camera section 142, and a liquid 15. Moreover, the camera section 142 consists of a CCD and an amplifier and connects to an external electric device such as a monitor via a power supply line 143 and a video signal line 144. A change in an external pressure for electronic components employed for the camera section 142 is measured, and the change by the external pressure is similar to the change in a temperature under a normal pressure and the circuit is designed without a problem by the present circuit technology. Then the liquid in use requires a larger refractive index difference from that of a lens optically to the utmost and excellent transparency of the liquid is also one of requirements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device used under high pressure such as in the deep sea.

[0002]

2. Description of the Related Art A conventional image pickup device used under high pressure is
As shown in FIG. 1, a device used at normal pressure is put in a thick pressure-resistant case 1 for use. In the figure, 2 is a pressure resistant window, 3
Is an optical system, 4 is a camera, and the pressure-resistant case 1 has 1 atm. However, in this method, when the pressure becomes high, the case 1
Since it is necessary to increase the wall thickness of the case, there is a drawback that the case becomes large and heavy. In addition, since it is necessary to increase the thickness of the case 1 and simultaneously increase the thickness of the pressure resistant window 2, it is necessary to increase the aperture of the optical system accordingly. In that case, the optical system becomes large and heavy. There is. 2A and 2B are explanatory views showing that the diameter of the optical system must be increased depending on the thickness of the pressure resistant window. FIG. 2A shows a case where the pressure resistant window 1'is thin, and FIG. 2B shows a case where the pressure resistant window 1 is thick. . When the pressure resistant window 1'is thin, the size of the lens L1 and the position B of the image are as shown in (a), but when the pressure resistant window 1 is thick as shown in (b), the working distance (WD) is increased.
In order to obtain images of the same size, the lens L2 must have a large aperture as shown in the figure, and when the distance to the image forming position is small and the pressure resistant window thickness is thin. It becomes larger than that. S1 + S2 <S2 ′ + S2 ′ Further, when the breakdown voltage window becomes thicker, it causes deterioration of optical characteristics.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image pickup device which is small in size and light in weight and is used under high pressure without image deterioration due to distortion of a pressure resistant window.

[0004]

The present invention has solved the above-mentioned problems by an idea which is completely opposite to the conventional one. That is,
The present invention is not to use a pressure resistant container, but to use a non-pressure resistant container, the optical system and the camera for sending a video signal are put in a closed container provided with a window and an internal / external hydraulic pressure equalizing valve, and It is filled with a liquid that does not attack the built-in one. A diaphragm, a bellows or the like is used as the internal / external hydraulic pressure equalizing valve.

[Function] Even if external pressure is applied, the sealed container is filled with liquid, and the pressure difference between the inside and the outside is adjusted by the internal and external hydraulic pressure equalizing valves, so even if the sealed container is thin, it will not be crushed by external pressure. . In addition, since the optical system and the camera have a structure in which air does not remain, the built-in objects are not damaged.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows an embodiment of the present invention, in which 11 is a hermetically sealed storage case which is thinner than a conventional pressure-resistant case in which only strength by impact is taken into consideration, 12 is a window, 13 is a bellows attached to the storage case 11, Reference numeral 14 is an image pickup device including an optical system portion 141 and a camera portion 142, and 15 is a liquid. As the optical system portion 141, a reflection optical system or a refraction optical system is used.
It is determined by the formula of the reflection angle, and the characteristics do not change in air and liquid. On the other hand, in the case of a refraction optical system, the characteristics are completely different because the refractive index is different between liquid and air. For example, as shown in FIG. 4, the focal length f of the plano-convex single lens in the air is
Is 1 / f = 1 / r (N−1) where r is the radius of curvature of the lens and N is the refractive index of the lens. On the other hand, the focal length fe in the liquid having the refractive index Ne is 1 / fe = 1 / r × (N-Ne) / Ne. Generally, Ne ≠ 1, so that fe ≠ f. However, by changing the radius of curvature r to re = r (N-1) (N-Ne) / Ne, a lens having the same focal length can be designed. The camera portion 142 in the embodiment is composed of a CCD and an amplifier, and has a power supply line 143 and a video signal line 1.
It is connected via 44 to an external electric device such as a monitor. Although the changes due to the external pressure of the electric components used in the camera portion 142 have been measured, the changes due to these external pressures are almost the same as the changes due to the temperature at normal pressure and can be designed by the current circuit technology without any problem. However, a high-capacity capacitor that breaks under high voltage must be replaced with a plurality of small-capacity capacitors. Since solid-state imaging devices such as CCD devices used as imaging devices are made by semiconductor technology, it has been experimentally confirmed that the characteristics do not change even if the hydraulic pressure changes. There is. By the way, the liquid used in the present invention requires some conditions. First, it is necessary to have an optical difference as large as possible from the lens material. This is because if the difference in refractive index is small, the radius of curvature of the lens becomes large even if a lens having the same focal length is designed, spherical aberration increases, and the image deteriorates. It is also a condition that the liquid has good transparency. The liquid conditions seen from the viewpoint of electrical parts are as follows: (1) high insulation resistance (2) low dielectric loss. In addition, generally required conditions include (3) chemical stability, (4) not attacking the structure, etc. A liquid satisfying these conditions is CF ₃ (CF
₂ ) There is a fluorine compound represented by nCF ₃ . However, n is a positive integer. In the example, n = 4 CF ₃ (CF ₂ ) ₄ CF
₃ (perfluorohexane) was used. This liquid has a refractive index of 1.2515, and can have a relatively large difference in refractive index with respect to a commonly used lens material (refraction of 1.5 to 2.0). The refractive index of a general liquid is shown in Table 1 for reference.

[0006]

[Table 1]

Further, CF ₃ (CF ₂ ) ₄ CF ₃ is chemically stable and has excellent properties such as insulation and dielectric loss. Freon can also be used.

[0008]

Since the hermetically sealed case of the present invention has an internal and external pressure equalizing structure that does not collapse even when used under high pressure, the meat pressure can be made thin, so that it can be made compact and lightweight. . Further, in the case of the conventional pressure resistant window, distortion occurs in the image because distortion occurs when used under high pressure, but since the window of the device of the present invention does not generate distortion even when used under high pressure, The one without distortion is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional imaging device used under high pressure.

FIG. 2 is a diagram showing a difference in an optical system when a window of a case is thin and when it is thick.

FIG. 3 is a sectional view of an embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a focal length and a radius of curvature of a plano-convex single lens.

[Explanation of symbols]

 1, 1'window 2 pressure resistant window 3 optical system 4 camera 11 case 12 window 13 bellows 14 camera 15 liquid 141 optical system part 142 camera part 143 power supply line 144 video signal line

Claims (2)

[Claims] 1. A high pressure device characterized in that an optical system and a camera for transmitting a video signal are put in a sealed case provided with a window and an internal / external hydraulic pressure equalizing valve, and a liquid that does not damage the built-in one is filled. Imaging device used in. 2. The imaging device used under high pressure according to claim 1, wherein the liquid is a fluorine compound.