Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1998-05-07
2001-01-23
Lieu, Julie (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S603000, C340S612000, C340S619000, C250S902000, C250S904000, C250S577000, C073S293000
Reexamination Certificate
active
06177874
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 87205094, filed Apr. 4, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a liquid supplying device. More particularly, the present invention relates to a liquid supplying device equipped with a liquid level sensor suitable for providing a chemical solution to a spin-on-glass (SOG) station.
2. Description of Related Art
FIG. 1
is a sketch showing a conventional liquid supplying device. The liquid supplying device utilizes a capacitor-type of sensor for detecting liquid level. In
FIG. 1
, the liquid supplying device includes a liquid container
10
placed within an external vessel
11
. The liquid container
10
contains a chemical solution
12
, and the whole assembly including the solution
12
, the liquid container
10
and the external vessel are placed over a capacitor sensor
13
.
Chemical solution
12
within the container
10
is able to flow out through a capillary tube to supply a SOG station. As the chemical solution
12
inside the container
10
is gradually used up, the capacitor sensor is able to detect a drop in weight for the whole assembly. Eventually, when the liquid level has dropped below a minimum, a warning signal is emitted so that a user can replenish the chemical solution
12
in the container
10
, or simply replace the container
10
. Since SOG station must receive the chemical solution
12
continuously, a reliable method of detecting liquid level in a supplying device before the chemical solution
12
runs out is very important.
However, the chemical solution
12
in the liquid container
10
is capable of reacting with air to form crystal particles. These crystal particles add some weight to the whole assembly that includes the chemical solution
12
, external vessel
11
and liquid container
10
. Therefore, it is possible that even when all the chemical solution
12
inside the container
10
has already been used up, the overall weight is still not low enough to generate any warning signal. Alternatively, if the sensitivity of the capacitor sensor
13
is low, a warning signal may be emitted even though the liquid level in the container
10
is still relatively high.
Consequently, there is an error in detecting the amount of residual solution in the container
10
with a conventional capacitor type of sensor. Hence, problems such as a warning signal not being emitted in time to allow for the replenishing of solution or a false alarm being given when the container is still relatively full can occur from time to time.
In light of the foregoing, there is a need to provide a liquid supplying device equipped with a better level-sensing device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is to provide a liquid supplying device that has a detecting device capable of accurately monitoring the amount of residual liquid within a container.
In another aspect, this invention provides a liquid supplying device whose minimum amount of residual liquid within a container before triggering an alarm can be adjusted according to specific needs.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a liquid supplying device. The device comprises a liquid container for storing a liquid and a liquid level sensor for detecting the liquid level. The liquid level sensor is fixed relative to the bottleneck of the liquid container. As the liquid within the liquid container is gradually used up, liquid level drops. As soon as the remaining liquid in the container drops to a predetermined amount, the liquid level sensor will emit a signal warning the operator that the liquid level is too low, and is time to replenish liquid. Furthermore, by simply lowering or raising the liquid level sensor relative to the liquid container, the amount of liquid remaining in the container before a warning signal is emitted can be set to meet the demands in different situations.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4468567 (1984-08-01), Sasano et al.
patent: 4713552 (1987-12-01), Denis et al.
patent: 4880971 (1989-11-01), Danisch
patent: 4899585 (1990-02-01), Kulha
patent: 5077482 (1991-12-01), Vali et al.
patent: 5384515 (1995-01-01), Head et al.
patent: 5684296 (1997-11-01), Hamblin et al.
Cheng Ching-Chih
Fang Wen-Liang
Huang Kuo-Feng
Ma Hung-Lung
Lieu Julie
Thomas Kayden Horstemeyer & Risley
United Microelectronics Corp.
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