Method of announcing low level of remaining liquid in dropper

• US RE34,073 E
• Filed: 01/03/1991
• Issued: 09/22/1992
• Est. Priority Date: 02/10/1988
• Status: Expired due to Fees

• Current Assignee: TOHO Plastic Company Limited
• Original Assignee: TOHO Plastic Company Limited
• Inventors: Suzuki, Takeo
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US07/637,572
• Time in Patent Office: 628 Days
• Field of Search: 73/304 C, 340/620, 324/687, 324/660, 324/689
• US Class Current: 324/687
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold

Abstract

This invention relates to a method of annoucing a low level of the remaining liquid in a dropper. According to the present invention, two electrodes are attached to the outer surface of a dropper, and a pulse of a stable level is applied to one of these electrodes. The remaining quantity of the liquid in the dropper can be detected automatically with ease by utilizing the variations of the electrostatic capacity occurring between these two electrodes. An annunciator is activated when it receives a signal representative of a low level of the liquid in the dropper, to inform a nurse of the necessity of replacing the dropper.

Claims

1. A method of announcing a low level of the remaining liquid in a dropper, comprising the steps of:

applying a pulse of a stable level to at least one of detecting electrodes attached to an outer surface of a lower portion of a liquid-containing dropper;

comparing a level of said pulse passed through an interior of said dropper with a reference pulse level, said reference pulse level being between a level of said pulse passed through said interior of said dropper when said liquid exists therein for defining an electrostatic capacity between said detecting electrodes and that of said pulse passed through said interior of said dropper when a remaining quantity of said liquid in said dropper decreases to such an extent that a significantly reduced electrostatic capacity is defined between said detecting electrodes; and

automatically actuating an annunciator when a judgement signal representative of unfavorable results derived from said step of comparing with said reference pulse level.

2. The method of announcing a low level of the remaining liquid in a dropper as in claim 1, wherein said step of applying a pulse of a stable level includes the steps of applying a certain level of pulses to an electrode, and obtaining a level of pulses at another electrodes, and wherein said step of comparing with said reference pulse level includes the step of comparing said level of pulses at said another electrode with said reference pulse level.