An asic for sensor signal processing for period measurement and its application

Abstract

The present invention provides a full custom ASIC (integrated circuit designed for a specific application) for sensor signal processing, said ASIC is specially designed to eliminate systematic errors in periodic measurement of periodic reciprocating motion; said ASIC has 5 The first pin is the positive pin of the power supply, the second pin is the control signal pin, which is used to connect to the CPU or the instrument control circuit, and the third pin is the signal input end, which is used to connect the photogate circuit output terminal, the fourth pin is a signal output terminal for connecting timers and counters, and the fifth pin is a power ground pin; the ASIC cancels the operational amplifier, voltage comparator, A / In the D converter, the entire circuit is composed of CMOS circuits to form a switch circuit, so the circuit structure of the present invention is simpler, the anti-interference ability is stronger, and the circuit power consumption is lower.

Description

technical field [0001] The invention relates to a period accurate measurement method of periodic vibration and an integrated circuit for measurement. Background technique [0002] The systematic error refers to the difference between the average result of the same large number of repeated measurements and the true value of the measurement. The systematic error in physical measurement usually comes from: (1) Instrument error, which is caused by the defect of the instrument itself or the failure to use the instrument according to the specified conditions. For example, the zero point of the instrument is not accurate, the instrument is not adjusted well, and the external environment (light, temperature, humidity, electromagnetic field, etc.) The approximation of the theoretical formula itself, or the experimental conditions cannot meet the requirements specified in the theoretical formula, or the error caused by the imperfection of the experimental method itself, for example, ...

AI Technical Summary

Problems solved by technology

[0009] This measurement device counts the swing of the single pendulum through the change of the magnetic induction line passing through the Hall element. Compared with the traditional measurement method, it gets rid of the subjective error of human measurement, but the device still has several insurmountable defects: ( 1) Since the signal generated by the Hall element in the changing magnetic field has a certain hysteresis, there is a certain time difference ΔT between each measured pendulum cycle and the real pendulum cycle; (2) and the magnet and the iron ball interact with each other The action time is short, so it is easy to cause the step loss of the Hall element during the measurement process; (3) Due to the use of magnetism as the signal trigger, it is easy to be interfered by the outside world; (4) Due to the measurement principle, the Hall element must be placed strictly In the balance position of the pendulum (the lowest point of the pendulum movement), it is actually difficult to strictly meet this condition, and the Hall element usually deviates from a certain distance, resulting in inaccurate period measurement

However, when it is used to measure the period of a pendulum, the device still has the following theoretical defects: (1) The photogate must be strictly placed at the equilibrium position of the pendulum (the lowest point of the pendulum movement), but in fact it is very If it is difficult to strictly meet this condition, the photogate usually deviates from a certain distance, resulting in inaccurate period measurement; (2) When the photodiode sensor of the photogate is periodically blocked during the reciprocating motion of the ball, the light It cannot be blocked or moved away instantly, and the light intensity it receives varies with the process of swinging the ball from left to right and from right to left, but its output signal has a short-term transient process. As a result, the time point indicating the passing of the pendulum ball in different directions does not exactly correspond to the same position, which leads to a certain error in the period measurement of the simple pendulum; (3) Due to the limitation of the principle of the voltage comparator, During the reciprocating motion of the pendulum ball, the input signal of the voltage comparator changes from small to large, and from large to small. In these two opposite processes, the output signal of the voltage comparator cannot jump at the same voltage value point, but There is a certain hysteresis, which makes the period measurement of the simple pendulum inherently impossible to accurately determine

In this technical solution, there are still (including but not limited to) the following defects: (1) The PNP three-wire inductive normally open proximity switch is required to be strictly placed at the lowest point of the pendulum ball movement, which is actually difficult to strictly achieve this point , leading to inaccurate period measurement; (2) Inductive proximity switches also have hysteresis, that is, during the movement of the pendulum ball from left to right and from right to left, the switch opening and closing actions do not strictly occur in different directions of movement. The same position point, but a slight deviation, which is one of its essential properties, is an insurmountable defect, and it is difficult to accurately measure the period of a simple pendulum

[0021] It is worth pointing out that, from the theoretical analysis process, it can be seen that the above-mentioned various technical defects only exist in the periodic measurement of periodic reciprocating motion, and do not exist when the measured motion is unidirectional motion.

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