Patent ID: 9658630
Date: 2017-05-23
CPC Classifications: G05F

Claim:
1. A digital filter comprising: a minimum-value holder that holds a minimum value of a measurement value inputted in the minimum-value holder and that outputs the minimum value as a held value; a limit-value circuit that receives the held value and that outputs the held value as a limit value in a case where the held value remains minimum during predetermined cycles; an output controller that receives a maximum value, the measurement value, and the limit value, the maximum value defining an upper limit, outputs the measurement value as an output value if the measurement value is smaller than the limit value, and outputs the maximum value as the output value if the measurement value is equal to or larger than the limit value; a first-maximum-value generator including a moving-average filter that receives the measurement value and generates a first maximum value by taking a moving average of the measurement value in L cycles; a second-maximum-value generator that receives the output value, delays the output value in J cycles, and generates a second maximum value by adding 1 to the delayed output value; and a minimum-value selecting and holding device that outputs a smaller one of the first maximum value and the second maximum value, as the maximum value.