Object detection device

An object detection device comprising:

• a signal generating unit that generates a pulse signal of a frequency fp;
• a transmission unit that converts the pulse signal into a probe wave being an ultrasonic wave and transmits the probe wave;
• a receiving unit that receives an ultrasonic wave;
• a distance calculating unit that calculates a distance to an object based on a time from transmission of the probe wave by the transmission unit to reception of a reflected wave of the probe wave by the receiving unit;
• a determination unit that determines whether an ultrasonic wave received by the receiving unit is a reflected wave of the probe wave;
• an amplitude detecting unit that detects an amplitude Ar of the ultrasonic wave received by the receiving unit;
• and
• a frequency detecting unit that detects a frequency fr of the ultrasonic wave received by the receiving unit, wherein
• when an amplitude of the probe wave is defined as At,
• the transmission unit has a characteristic that the amplitude At has a predetermined reference value At1 or more when the pulse signal is continuously inputted thereinto at a frequency included in a predetermined range,
• the signal generating unit generates the pulse signal so that the amplitude At has the reference value A1 or more when a predetermined time has elapsed from start of generation of the pulse signal, the signal generating unit also sweeping the frequency fp from a minimum value to a maximum value or from the maximum value to the minimum value in the predetermined range after the predetermined time has elapsed from start of generation of the pulse signal,
• the determination unit determines that the ultrasonic wave received by the receiving unit is a reflected wave of the probe wave when the frequency fr makes the same change as the frequency fp, and
• the distance calculating unit, when the determination unit determines that the ultrasonic wave received by the receiving unit is the reflected wave of the probe wave, calculates the distance to the object based on a time from transmission of the probe wave by the transmission unit to reception of the ultrasonic wave by the receiving unit.

An object detection device, comprising:

• a signal generating unit that generates a pulse signal;
• a transmission unit that converts the pulse signal into a probe wave being an ultrasonic wave and transmits the probe wave;
• a receiving unit that receives an ultrasonic wave;
• a distance calculating unit that calculates a distance to an object based on a time from transmission of the probe wave by the transmission unit to reception of a reflected wave of the probe wave by the receiving unit;
• a determination unit that determines whether an ultrasonic wave received by the receiving unit is a reflected wave of the probe wave;
• and
• a frequency detecting unit that detects a frequency of the ultrasonic wave received by the receiving unit, wherein
• the pulse signal includes a first pulse signal and a second pulse signal,
• the signal generating unit sweeps frequencies of the first pulse signal and the second pulse signal while the transmission unit transmits the probe wave,
• fAs<fAe, fBe<fBs, fAs<fBs, and fBe<fAe are satisfied whenin
• fAs is a frequency of the first pulse signal at start of sweeping,
• fAe is a frequency of the first pulse signal at the end of sweeping,
• fBs is a frequency of the second pulse signal at start of sweeping, and
• fBe is a frequency of the second pulse signal at the end of sweeping,
• the determination unit determines that the ultrasonic wave received by the receiving unit is a reflected wave of the probe wave when the frequency detecting unit detects a plurality of frequencies, and the plurality of frequencies detected by the frequency detecting unit include frequencies making the same change as the frequencies of the first pulse signal and the second pulse signal, and
• the distance calculating unit, when the determination unit determines that an ultrasonic wave received by the receiving unit is a reflected wave of the probe wave, calculates the distance to the object based on a time from transmission of the probe wave by the transmission unit to reception of the ultrasonic wave by the receiving unit.