초록 ▼

A hot-wire level detecting apparatus includes a micro-processor which registers a look-up table of digital level values associated with digital values of a differential parameter representing the change in the voltage or current in the hot-wire probe. The micro-processor controls a switch for initia

A hot-wire level detecting apparatus includes a micro-processor which registers a look-up table of digital level values associated with digital values of a differential parameter representing the change in the voltage or current in the hot-wire probe. The micro-processor controls a switch for initiating the application of power to the probe. In one embodiment a constant voltage supply is connected across the emitter and collector of a transistor with the probe in the emitter circuit and a resistor in the collector circuit. The voltage across the resistor, measured at switch-on and after a period for stabilization, is fed to the micro-processor by an analog-digital converter.

대표청구항 ▼

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying el

An apparatus for determining a level of a liquid in a tank comprising: a temperature dependent resistive wire probe at least partially immersed in said liquid in a generally vertical orientation in said tank, said resistive probe sensing variations in the liquid level; a power supply for applying electrical energy to said resistive wire probe; means for detecting an electrical parameter in said resistive wire probe; means for memorizing an initial value of said electrical parameter when electrical energy is applied to said resistive wire probe; means for monitoring any variation in said electrical parameter from its initial value and for generating a differential parameter representative of the variation in said electrical parameter, said differential parameter being related to the level of liquid; converting means for converting said differential parameter into digital values; means for storing a plurality of correspondence tables defining digital corrections of the differential parameter digital values generated by said converting means said tables being associated with initial values of said parameters being detected; means for selecting the associated one of said plurality of correspondence tables depending upon the memorized initial value of said electrical parameter being detected; means for determining from said selected correspondence table, a digital correction corresponding to the differential parameter digital value generated by said converting means, and for generating a corrected differential parameter digital value.