Patent ID: 8535229

Claim:
An ultrasonographic device for imaging the inside of an examinee, comprising: transmission means configured to transmit an ultrasonic pulse signal from a transmission aperture of an ultrasonic element array to an examinee, the transmission means being configured to apply weighting to the transmission aperture of the ultrasonic element array using a Gaussian function, and to control a local focal length of the ultrasonic element array using a Lorentz function during one scanning period; and reception means which receives the ultrasonic pulse reflected from the examinee, wherein the transmission means is configured to tune a combination of: a parameter β of a differential said Gaussian function determining a spread of a transmission aperture weight, and a parameter α of the Lorentz function determining tendency of a change in the local focal length, to effect the transmitted ultrasonic pulse signal to contain a plurality of peaks with substantially equal transmission intensity in an azimuth direction, a locus in a depth direction of each peak from the plurality of peaks is a substantially straight line parallel with scan lines of a sector scan, and the Lorentz resonance function is expressed as a function of coordinates x and y on an array as follows: f ⁡ ( x , y ) = f 1 - ( 1 + α 1 + α 2 1 + α 1 ⁢ x 2 + α 2 ⁢ y 2 - 1 ) ⁢ f 1 - f 0 α 1 + α 2 wherein α 1 and α 2 are parameters of the Lorentz resonance function determining tendency in the local focal length and the Lorentz resonance function is set so that transmission beam widths are made constant in a range from a near local focal length f 0 to a far local focal length f 1 so it becomes possible to form four lobes parallel with scan lines of the sector scan and to form a predetermined angle.