PURPOSE: To reduce a bottom face grooving time for suppressing a bulk wave and defective processing with small amplitude and phase ripples by forming a groove with a prescribed depth to a rear side of a SAW substrate at a specific angle in a progressing direction of a BGS wave. ;CONSTITUTION: A BGS wave use IDT is formed on the surface of a SAW substrate 1 and plural grooves 1a whose depth is more than 33% of a thickness of the SAW substrate 1 are formed to the rear side at an angle of 45° in the progressing direction of a BGS wave (direction of the arrow). That is, since only the 45° grooves 1a are formed to the SAW substrate 1, number of the grooves 1a is less than that of a conventional device, a total area of the bottom faces of the grooves 1a is small, resulting that a reflected bulk wave from the groove bottom faces is decreased. Thus the working time of the grooves 1a is short and defective working is reduced. Moreover, when the device is applied to a TV or a VTR, uneven lightness and color slurring are reduced because of the reduction in amplitude and phase ripples.;COPYRIGHT: (C)1996,JPO
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