Digital display tape measure and measuring method thereof

A digital display tape measure, comprising a housing, a tape measure mechanism, a digital display sensor, a display screen, and a control circuit board;

• wherein the tape measure mechanism is disposed inside the housing, a plurality of dark stripes are disposed on a tape of the tape measure mechanism at equal intervals, the digital display sensor is configured to cooperate with the tape measure mechanism, the display screen is configured to display a feedback result of the digital display sensor, the control circuit board is electrically connected to the digital display sensor and the display screen, and the control circuit board is integrated with a microcontroller unit (MCU);
• wherein the digital display sensor comprises a signal acquisition module and a signal processing module;
• wherein the signal acquisition module comprises at least one photoelectric sensor group;
• each of the at least one photoelectric sensor group comprises three consecutively and equidistantly arranged photoelectric sensors, and a signal acquisition circuit electrically connected to the photoelectric sensors;
• the photoelectric sensors are respectively configured to acquire a first signal, a second signal, and a third signal;
• a phase difference between output waveform signals of the first signal and the second signal and a phase difference between output waveform signals of the second signal and the third signal each are 90 degrees (°);
• wherein the signal processing module comprises a first comparator, a second comparator and a signal processing circuit;
• a fourth signal is configured to be generated by averaging a sum of the first signal and the third signal, a negative input terminal of the first comparator and a negative input terminal of the second comparator are configured to connect the fourth signal, a positive input terminal of the first comparator is configured to connect the first signal, and a positive input terminal of the second comparator is configured to connect the second signal;
• the first comparator is configured to compare the first signal with the fourth signal, and output a first comparison signal being a high level when the first signal is greater than the fourth signal or being a low level when the first signal is less than the fourth signal;
• and the second comparator is configured to compare the second signal with the fourth signal, and output a second comparison signal being a high level when the second signal is greater than the fourth signal or being a low level when the second signal is less than the fourth signal;
• and
• wherein the MCU is electrically connected to the first comparator, the second comparator, the photoelectric sensors, the signal acquisition circuit, the signal processing circuit, and the display screen;
• and the MCU is configured to perform counting by acquiring a rising edge and a falling edge of the first comparison signal or the second comparison signal, determine a displacement direction of the tape based on a phase difference between the first comparison signal and the second comparison signal, calculate out displacement, and output the displacement to the display screen.