Column type polar distance variable capacitance weighing sensor

Abstract

The invention relates to a column type pole distance variable capacity weight-sensor used in electric weight system. It is formed by a weight-bearing head, a moving column, a capacity upper polar plate, a capacity lower polar plate, a weight-bearing spring, an outer cylinder and a bed and so on, wherein the capacity upper and lower polar plate and the weight-bearing spring are sealed fixed inside the outer cylinder. The gravity action of the object in on the weight-bearing head; it presses the weight-bearing spring by moving cylinder so that the condense deformation of the weight-bearing spring makes the distance between the capacity upper and lower polar plates short and the capacity value between the capacity upper and lower polar plate larges. It uses the external capacity testing circuit to measure the capacity value between the capacity upper and lower polar plate to obtain the weight value of the object.

Description

1. Technical field [0001] The invention relates to a capacitive sensor for electronic weighing apparatus. 2. Background technology [0002] At present, resistance strain type load cells are widely used in electronic weighing instruments. Due to the limitation of strain limit, the relative change of the resistance of the metal strain wire of this resistance type sensor is generally less than 1%, and the resistance value of the strain wire is affected by temperature. very big. In contrast, the relative change in capacitance of capacitive sensors can be greater than 100%, so the measurement range is much larger; capacitive sensors generally use metal as electrodes and inorganic materials as insulating supports, so they can withstand large temperature changes. In addition, the capacitive sensor also has the advantages of high sensitivity, short dynamic response time, and small mechanical loss. [0003] The main reason why capacitive sensors are still rarely used is that the ca...

AI Technical Summary

Problems solved by technology

The existence of stray capacitance not only reduces the measurement sensitivity, but also causes nonlinear output, and even makes the sensor in an unstable working state

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