Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating
Patent
1995-05-12
1997-02-25
Vargot, Mathieu D.
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
73295, 73304R, 264 404, 425147, 425808, B29D 1100
Patent
active
056056567
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a liquid filling method and a lens manufacturing method, and more specifically, to a liquid filling method of filling a vessel with a lens material liquid and a lens manufacturing method using the liquid filling method.
BACKGROUND ART
A plastic lens is manufactured in such a manner that a cavity is formed between a casting gasket and upper and lower molds, and plastic monomer as a lens material is filled into the cavity and polymerized.
At that time, the plastic monomer must be filled thereinto in an accurate amount. The following methods are conventionally employed as a method which provides accurate filling of the material.
As a first method, the cubic content of a cavity is previously measured and an amount of a liquid corresponding to the cubic content is filled into the cavity.
As a second method, the liquid level is detected in a non-contact manner using a capacitive sensor so as to accurately control an amount to be filled.
As a third method, after a liquid is filled into a vessel, the liquid overflowing from the vessel is absorbed in vacuum so as to detect the filling of the liquid by making use of a pressure difference in a vacuum circuit between a pressure when a gas is absorbed before the liquid overflows and a pressure when the overflown liquid is absorbed, as shown in Japanese Laid-Open Patent Publication No. Hei 4(1992)-128617.
However, according to the first method, when the inside volumes of cavities have dispersion or when an amount of a liquid to be filled thereinto cannot be accurately controlled, the liquid overflows from the cavity or the cavity is insufficiently filled conversely and bubbles remain in the cavity.
According to the second method, it is difficult to miniaturize the capacitive sensor and it is therefore difficult to obtain a capacitive sensor applicable to a lens making cavity. Moreover, it is inherently difficult to improve the accuracy of the capacitive sensor.
Further, according to the third method, a vessel can be filled with a liquid with a high accuracy regardless of a type of a liquid, a shape of a cavity, and the dispersion of the inside volumes of cavities. On the other hand, in the third method, an absorbing pressure must be accurately adjusted. Further, when a liquid having a high polymerizing speed is absorbed, an absorbing pipe is clogged.
DISCLOSURE OF THE INVENTION
Taking the above into consideration, an object of the present invention is to provide a liquid filling method capable of accurately filling a liquid without being affected by the material of the liquid to be poured and the dispersion of the volumes of vessels.
Another object of the present invention is to provide a lens material liquid filling method capable of accurately filling a lens material liquid without being affected by the type of the lens material liquid and the dispersion of the volumes of cavities.
A further object of the present invention is to provide a lens manufacturing method capable of manufacturing a high quality lens by accurately filling a lens material into a cavity.
To accomplish the above objects, according to the present invention, there is provided a liquid filling method of controlling an amount of a liquid to be filled into a vessel, comprising the steps of setting and keeping a thermal sensing portion of a temperature sensor to a temperature different from that of the liquid, pouring the liquid into the vessel, detecting a change of an output from the temperature sensor when the surface of the liquid comes into contact with the thermal sensing portion and stopping the filling of the liquid when it is determined that the liquid surface has reached a desired level.
There is also provided a lens material liquid filling method of controlling an amount of a lens material liquid to be filled into a cavity, comprising the steps of setting and keeping a thermal sensing portion of a temperature sensor to a temperature different from that of the lens material liquid, pouring the lens material liquid into a vessel, detectin
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patent: 4583401 (1986-04-01), Schlindwein et al.
patent: 4594064 (1986-06-01), Anderson
patent: 4956134 (1990-09-01), Luc
Hoya Corporation
Vargot Mathieu D.
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