Patent ID: 8786420

Claim:
A drive recorder, comprising: a trigger judgment circuit that calculates, with respect to acceleration data of a vehicle, first and second moving averages as moving averages of two different time series, and that generates a trigger signal according to a result of comparing a differential value or an absolute differential value of the first and second moving averages with a predetermined threshold value, wherein the first and second moving averages are values that are calculated with respect to acceleration data in two different time spans that are continuous and that partly overlap by overlapping acceleration data, the trigger judgment circuit includes: a register that stores the acceleration data therein; an averaging processing portion that calculates the first moving average, using m latest samples of acceleration data among n samples of acceleration data stored in the register, by calculating a total sum of the m latest samples of acceleration data and dividing the resulting total sum by a sampling number k of moving averaging processing, and the second moving average, using m oldest samples of acceleration data among the n samples of acceleration data stored in the register, by calculating a total sum of the m oldest samples of acceleration data and dividing the resulting total sum by the sampling number k of the moving averaging processing; a subtraction processing portion that calculates the differential value or the absolute differential value of the first and second moving averages that are calculated by the averaging processing portion; and a threshold-value comparison portion that compares the differential value or the absolute differential value of the first and second moving averages that is calculated by the subtraction processing portion with the predetermined threshold value to thereby generate the trigger signal.