JPS58190738A - Pressure sensor using liquid lens - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thick-walled fluid in which at least a portion of the body is under the influence of the pressure to be measured, and the light entrance surface and the light exit surface are isolated from the pressure space to be measured. This invention relates to a new pressure sensor using an integrated lens.

Conventionally, pressure sensors have been known based on various principles, such as those that utilize the expansion and contraction of bellows and those that utilize a resistance wire strain meter, but the present invention is based on a completely new principle.

A first object of the invention is to provide a pressure sensor that is compact, robust and non-explosive.

A second object of the present invention is to provide a pressure sensor that can be remotely monitored using light.

The structure and operation of the present invention will be explained below with reference to the illustrated embodiments. - In the embodiment shown in FIG. 1, A is a thick liquid lens, B is a lens holder, 01 is a light projecting surface of a light projector, and O2 is a light receiving surface of a light receiver.

The thick liquid lens A is formed of a lens outer shell 1 made of an elastically deformable transparent plastic material and a transparent liquid 2 sealed inside the lens outer shell, and further includes lens protection and light shielding as necessary. A band member 3 which also serves as a belt member is attached to the body part to protect it and block external light.

The lens holder B includes a wall portion 11, a lens holder 12, and a projector mounting portion 13 for shielding the light incident surface and light output surface (spherical surface) of the lens from the pressure space to be measured and for shielding external light. , a light receiver mounting part 14 is provided, and a lens holding part 1 is provided.
2 is provided with a window 15 so that the measured voltage P in the external space of the lens holder B can affect the body of the liquid lens A.

A liquid lens A is held in the lens holding portion 12 via an expandable rubber seal 16 so as to maintain airtightness inside and outside the case.

The light projector holder 13 has an optical fiber 21 as a light projector.
is held by an elastic glove 22, a nut 23, and a rubber bush 24, and an optical fiber 25 as a light receiver is held in the receiver holding part 14 by an elastic plug 26, a nut 27,
It is held by a rubber bush 28.

Examples of the material for the lens outer shell 1 include polysilane methacrylate (refractive index 1.507 at 15°C),
Plastics such as polystyrene (refractive index 1.592 at 15°C), polymethyl methacrylate (refractive index 1.491 at 2°C) are suitable.

Examples of liquids to be filled in the lens outer shell 1 include glycerin (refractive index 1.473 at 20°C), carbon tetrachloride (refractive index 1.461 at 20°C), seda oil (20°C
(refractive index 1516 at 20°C), paraffin oil (refractive index 1 at 20°C)
．． 48), benzene (refractive index 1.501 at 20°C), etc. are suitable.

FIG. 2 is a diagram for explaining the principle of operation of the present invention. In Figure 2 (α), the radius of curvature r of both convex surfaces of the lens
is 28, the thickness d is 46, and the refractive index n of the lens material is 1.
．． 45, the refractive index no of each space on the light emitting side and the light receiving side is 1
．． o, the focal length f is each distance. The incident light ray L1 parallel to the optical axes Fl and FZ reaches the second focal point F2 via the optical path shown by the solid line, but according to the calculation, it goes straight to the second principal surface H2 as shown by the dotted line, and then reaches the second principal surface. It is safe to assume that the light is refracted at H2 and heads toward the second focal point F2. The first and second principal surfaces are virtual surfaces that serve as a reference for focal length measurement in this way.

FIG. 2(b) shows an optical system in an embodiment of the present invention, in which the end surface 01 of the optical fiber 21 serving as a projector is
Distance 2/ from 1 to end face 02 of optical fiber 25 serving as a light receiver
is arranged on the optical axis at a distance of 2f from the second principal surface H2. When the emitter and receiver are arranged in this way, the light transmitted through the optical fiber 21 and projected from the surface 01 is focused on the surface 02, and the other end of the optical fiber 25 (
(not shown) can detect the maximum output light.

Points OR and 02 having such a relationship are called mutually conjugate positions.

When the distance t of 0102 is adjusted so that when the pressure to be measured (the pressure applied to the lens body) is at the standard value, the state shown in Fig. 2(b) is reached, and the pressure to be measured increases, the liquid lens A is deformed as shown in FIG. 2(C). That is, the thickness is d'(d'〉d), and the radius of curvature is r'
(r'(r), the focal length becomes f'(f'<f), and 2f from the first and second principal surfaces H'i and H'2
’ point○’1. O'2 moves inward from 01 and 02, respectively. The conjugate point of 01 also moves from 02 to 0/4, and the light projected from 01 passes through the optical path shown by the solid line to Q4+
After being imaged, it is slightly diffused and a part of it is incident on the light receiving surface 02. Therefore, the output light from the other end (not shown) of the optical fiber 25 becomes considerably weaker than in the case of FIG. 2(h). That is, since the output light from the other end of the optical fiber 25 changes as a function of the pressure to be measured P, the pressure to be measured can be determined by measuring the intensity of the output light.

As can be seen from the dimensions of the liquid lens illustrated above,
The pressure sensor according to the present invention can be made extremely compact,
Since the structure is simple and robust, its range of applications is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an embodiment of the present invention, and FIG. 2 (α
) to (C) are drawings showing the operating principle of the present invention. Explanation of main symbols A: Liquid lens B: Case 21: Emitter (optical fiber) 25: Light receiver (optical fiber) Patent applicant Sumitomo Electric Industries, Ltd.

Claims (2)

[Claims] (1) A thick liquid lens composed of a lens outer shell made of an elastically deformable transparent plastic material and a transparent liquid filled and sealed inside the lens outer shell; at least a part of the body of the thick liquid lens; a lens holder that holds the thick liquid lens so as to place the part under the influence of the pressure to be measured and isolate the light entrance surface and the light exit surface from the pressure space to be measured; the light entrance surface of the thick liquid lens; a light projector disposed in the lens holding perfect circle so as to project light toward the lens; , a light receiver arranged to receive light emitted from the liquid lens; A pressure sensor using a liquid lens. (2) The pressure sensor according to claim 1, wherein the light projector and the light receiver are each an end of an optical fiber.