Abstract: A piezoelectric resonator includes: a piezoelectric plate having a vibrating portion surrounded by a peripheral portion; and an excitation electrode on the piezoelectric plate, wherein long sides of the vibrating portion and excitation electrode are parallel to a piezoelectric plate long side. Assuming a piezoelectric plate long side length X, a vibrating portion thickness t, a vibrating portion long side length Mx, an excitation electrode long side length Ex, and a piezoelectric plate flexure vibration wavelength ?, ?/2=(1.332/f)?0.0024 (piezoelectric resonator resonance frequency f), (Mx?Ex)/2=?/2, Mx/2={(½)+(¼)}? (where, I=1, 2, 3, . . . ), and X?20 t. A protruding portion is disposed on a vibrating portion extension line and parallel to a vibrating portion short side. Assuming a protruding portion length Dx, Dx=(?/2)×m (where, m=1, 2, 3, . . . ). Assuming a distance Sx between the vibrating and protruding portions, Sx=(?/2)×n±0.1? (where, n=1, 2, 3, . . . ).

Abstract: An AT cut quartz crystal resonator element includes a quartz crystal element piece having an exciting part formed from an AT cut quartz crystal plate in a rectangular shape having an X-axis direction of a quartz crystal set to a long side, and an exciting electrode formed on each of front and back main surfaces of the exciting part, in which each side surface in the longitudinal direction of the exciting part is composed of two faces, an m-face of a quartz crystal and a crystal face other than the m-face.

Abstract: An AT cut quartz crystal resonator element includes a quartz crystal element piece having an exciting part formed from an AT cut quartz crystal plate in a rectangular shape having an X-axis direction of a quartz crystal set to a long side, and an exciting electrode formed on each of front and back main surfaces of the exciting part, in which each side surface in the longitudinal direction of the exciting part is composed of two faces, an m-face of a quartz crystal and a crystal face other than the m-face.

Abstract: An AT cut quartz crystal resonator element includes a quartz crystal element piece having an exciting part formed from an AT cut quartz crystal plate in a rectangular shape having an X-axis direction of a quartz crystal set to a long side, and an exciting electrode formed on each of front and back main surfaces of the exciting part, in which each side surface in the longitudinal direction of the exciting part is composed of two faces, an m-face of a quartz crystal and a crystal face other than the m-face.

Abstract: An AT cut quartz crystal resonator element includes a quartz crystal element piece having an exciting part formed from an AT cut quartz crystal plate in a rectangular shape having an X-axis direction of a quartz crystal set to a long side, and an exciting electrode formed on each of front and back main surfaces of the exciting part, in which each side surface in the longitudinal direction of the exciting part is composed of two faces, an m-face of a quartz crystal and a crystal face other than the m-face.

Abstract: An AT cut quartz crystal resonator element includes a quartz crystal element piece having an exciting part formed from an AT cut quartz crystal plate in a rectangular shape having an X-axis direction of a quartz crystal set to a long side, and an exciting electrode formed on each of front and back main surfaces of the exciting part, in which each side surface in the longitudinal direction of the exciting part is composed of two faces, an m-face of a quartz crystal and a crystal face other than the m-face.

Abstract: A blade for the use of a rotary compressor includes a sintered body composed of 50 to 98.5 wt. % of zirconia, 1 to 49.5 wt. % of alumina and the reminder including 0.5 to 10 wt. % of a stabilizing material. The stabilizing material is comprised of at least one selected from magnesia, calcia, ceria and an oxide of an rare-earth metal and the grain size of the sintered body is less than 3 .mu.m. The zirconia in the sintered body is substantially formed with a tetragonal structure or a mixture of tetragonal and cubic structures.

Abstract: A sealed-type compressor used with HFC refrigerant. The sealed-type compressor houses a motor and compression machinery in a sealed case. The compression machinery includes at least a pair of sliding members wherein one sliding member having aluminum as its main body and having its surface alumite treated and the other sliding member having a metal material. The compressor includes an at least quadrivalent ester oil for the refrigerating machine oil which lubricates the sliding members.