Patent ID: 7694890

Claim:
A method for reading information by scanning a three-dimensional range of a passive ultrasonic tag ( 100 ) comprising: a tag body ( 102 ), and having two or more holes ( 106 , 108 , 110 ) disposed extensively on a surface ( 104 ) of the tag body, the holes having bottoms ( 112 , 114 , 116 ), the bottoms at predetermined depths dimensions (d 1 , d 2 , d 3 ) from the surface of the tag body (z), within the tag body, wherein depth dimensions of at least two of the two or more holes are set to different values (d 1 ≠d 2 , d 1 ≠d 3 , or d 2 ≠d 3 ), when a scan of ultrasonic waves is received across a three-dimensional range ( 104 to C+) including surfaces and bottoms of the two holes, the reflections of the ultrasonic waves will differ (R 1 , R 2 , R 3 ) based on settings of the bottoms of the two holes, wherein: the two or more holes ( 106 , 108 , 110 ) are aligned superimposed on openings that are opened in advance in two or more layers ( 410 , 420 , 430 ), comprising: across a two-dimensional range at a first depth: a step of transmitting ultrasonic waves from a transmitter to the passive ultrasonic tag; and a step of receiving the reflected ultrasonic waves by a receiver; and a step of changing the first depth to a second depth; and across a two-dimensional range at a second depth: a step of transmitting ultrasonic waves from a transmitter to the passive ultrasonic tag; and a step of receiving the reflected ultrasonic waves by a receiver; and a step of making a comparison between a reception state of ultrasonic waves in the two-dimensional range at the first depth and a reception state of ultrasonic waves in the two-dimensional range at the second depth.