Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Chemical analysis
Reexamination Certificate
1998-11-12
2001-12-25
Hilten, John S. (Department: 2854)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Chemical analysis
C702S056000
Reexamination Certificate
active
06334091
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a sensor for sensing concentrations of a solute in a solution and, in particular to method and apparatus for sensing concentrations of a solute in a solution such as a liquid ink or a liquid developer for use in a liquid developing electrostatic recording apparatus.
2. Description of the Related Art
There has been proposed a solute concentration detecting apparatus allowing automation of concentration adjustment in Japanese Patent Unexamined Publication No. 7-55682. More specifically, a solution reservoir is provided with a vertical passage through which two floats having different specific gravities are moving in a solution depending on the concentration of the solution. In the case of reduced concentration, one float having a smaller specific gravity is floating and the other having a greater specific gravity is sinking down As the concentration of the solute becomes higher, the other float having the greater specific gravity is floating and finally comes in contact with the one float having the smaller specific gravity. Therefore, when detecting the contact, it is determined that the concentration of the solution has reached the target concentration.
However, the above-mentioned concentration detecting apparatus can determine only whether the concentration of the solution has reached the target concentration. On other words, according to the conventional arrangement, only discrete concentration values are obtained. Therefore, precise concentration adjustment cannot be achieved.
Further, since the two floats are moving through the vertical passage, it is necessary to provide space for the vertical passage in the solution reservoir, resulting in increased size of the solution reservoir and reduced flexibility in design.
SUMMARY OF THE INVENTION
An object of the present invention is to provide solute concentration sensing method and apparatus that can sense the concentration of a solute with precision.
Another object of the present invention is to provide solute concentration sensing apparatus that can sense the concentration of a solute with reduced size and increased flexibility in design.
According to the present invention, two floats which are fixed to a rotation member and have different weights are placed within a reservoir storing the solution. A change in rotation angle of the rotation member is used as a change in concentration of the solution.
According to an aspect of the present invention, an apparatus includes a rotation member having a pair of floats fixed thereto at such positions that turning moment is produced due to one of a floating force and a sinking force for each of the floats, wherein the floats have different weights. The apparatus further includes a rotation angle sensor for sensing a change in rotation angle of the rotation member as a change in concentration of the solute in the solution.
According to another aspect of the present invention, an apparatus includes a rotation member having a pair of floats fixed thereto at such positions that turning moment is produced due to one of a floating force and a sinking force for each of the floats, wherein the floats have different weights and a rotation angle is sensor for sensing a change in rotation angle of the rotation member as a change in concentration of the solute in the solution, wherein a shaft of the rotation member is mechanically connected to a rotation axis of the rotation angle sensor. Further, the apparatus includes a casing containing the rotation member and having a plurality of openings formed so that the solution can flow through the openings, wherein the casing is fixed to the rotation angle sensor.
The rotation angle sensor may be fixed to a weight plate such that the rotation axis is perpendicular to the weight plate, the weight plate having a first portion and a second portion. The weight plate is rotatably connected at the first portion to an inner wall of the reservoir with a weight member fixed to the second portion thereof.
REFERENCES:
patent: 5485406 (1996-01-01), Wanda et al.
patent: 6026348 (2000-02-01), Hala
patent: 60-135745 (1985-07-01), None
patent: 7-55682 (1995-03-01), None
Foley & Lardner
Hilten John S.
NEC Corporation
Nolan, Jr. Charles H.
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