Patent ID: 8248887

Claim:
A physical object detection system comprising: at least one transmitting element for transmitting a transmission wave; at least two receiving elements for receiving a reflection wave, which corresponds to the transmission wave reflected by a physical object; and an electronic unit for detecting presence of the physical object based on a phase difference between the reflection waves received by the receiving elements, wherein the electronic unit includes: a detection section configured to detect a set of waves, each of which is a part of the reflection wave received by each of the receiving elements and has an amplitude greater than a predetermined level, a time difference between time points at which the amplitudes of the set of waves exceed the predetermined level is less than a predetermined time interval; and a determination section configured to determine presence of the physical object when the set of waves are detected between the receiving elements, and wherein: the detection section is configured to detect the set of waves, if the amplitudes of the set of waves are greater than a first predetermined level but the time difference between time points at which the amplitudes exceed the first predetermined level is greater than the predetermined time interval, by checking whether the amplitudes of the set of waves are greater than a second predetermined level greater than the first predetermined level, and the time difference between time points at which the amplitudes exceed the second predetermined level is less than the predetermined interval; and the determination section is configured to determine the presence of the physical object when the set of waves having the amplitudes greater than the second predetermined level and the time difference is less than the predetermined time interval.