Abstract: A digital displacement measuring instrument includes a spindle screwed into a body to be axially advanced and retracted relative to the body; and an encoder that detects a displacement of the spindle. The encoder includes a rotor and a stator. The rotor is supported by a rotor bushing. The rotor bushing includes an engaging key engageable with a key groove axially provided on the outer circumference of the spindle, and is displaceable in the axial direction of the spindle via a position adjusting screw. The stator is fixed to the body via a stator bushing in the vicinity of the spindle so as not to be displaceable in the axial direction of the spindle.

Abstract: An absolute position measuring apparatus includes a first rotary encoder that detects a rotation of a spindle as a phase signal which varies in a first cycle and a second rotary encoder that detects the rotation of the spindle as another phase signal which varies in a second cycle. A rotation of a first rotor of the first rotary encoder is transmitted to a second rotor via a relay gear that is meshed with a first gear provided on an outer circumference of a first rotary cylinder and a second gear provided on an outer circumference of a second rotary cylinder. Thus, an absolute position of the spindle is calculated on the basis of two phase signals that are different in cycle. Further, it is not necessary to provide a conventionally-known spiral key groove so that the apparatus can be easily downsized. Manufacturing costs can be also reduced.

Abstract: A rotor bushing restrictor (50) that prevents a rotor bushing (44) from moving away from a stator (42) is provided. The rotor bushing restrictor (50) includes a fixing member (51) fixed on a body and a rotor bushing attitude retainer (52) placed between the rotor bushing (44) and the fixing member (51). The rotor bushing attitude retainer (52) includes two first abutment portions (522) contacted with the rotor bushing (44) and two second abutment portions (523) contacted with the fixing member (51). The two first abutment portions (522) are symmetrically placed to each other with respect to the axis of the spindle (2), and the two second abutment portions (523) are symmetrically placed to each other with respect to the axis of the spindle (2). The two first abutment portions (522) and the two second abutment portions (523) are placed such that a straight line connecting the two first abutment portions (522) and a straight line connecting the two second abutment portions (523) are orthogonal with each other.

Abstract: An absolute position measuring apparatus includes a first rotary encoder that detects a rotation of a spindle as a phase signal which varies in a first cycle and a second rotary encoder that detects the rotation of the spindle as another phase signal which varies in a second cycle. A rotation of a first rotor of the first rotary encoder is transmitted to a second rotor via a relay gear that is meshed with a first gear provided on an outer circumference of a first rotary cylinder and a second gear provided on an outer circumference of a second rotary cylinder. Thus, an absolute position of the spindle is calculated on the basis of two phase signals that are different in cycle. Further, it is not necessary to provide a conventionally-known spiral key groove so that the apparatus can be easily downsized. Manufacturing costs can be also reduced.

Abstract: A rotation transmitter (44) includes a rotor support member (440) provided on an outer circumference of a spindle (2), a rotary piece (45) provided with an engaging portion (46) that is adapted to be engaged with an engaging groove (23), and a coil spring (48) provided between the rotary piece (45) and the rotor support member (440). The rotary piece (45) is supported by the rotor support member (440) in a manner rotatable in a circumferential direction of a rotation shaft (441) provided parallel to the axis of the spindle (2) and the coil spring (48) biases the engaging portion (46) onto the engaging groove (23) via the rotary piece (45).

Abstract: A rotor bushing restrictor (50) that prevents a rotor bushing (44) from moving away from a stator (42) is provided. The rotor bushing restrictor (50) includes a fixing member (51) fixed on a body and a rotor bushing attitude retainer (52) placed between the rotor bushing (44) and the fixing member (51). The rotor bushing attitude retainer (52) includes two first abutment portions (522) contacted with the rotor bushing (44) and two second abutment portions (523) contacted with the fixing member (51). The two first abutment portions (522) are symmetrically placed to each other with respect to the axis of the spindle (2), and the two second abutment portions (523) are symmetrically placed to each other with respect to the axis of the spindle (2). The two first abutment portions (522) and the two second abutment portions (523) are placed such that a straight line connecting the two first abutment portions (522) and a straight line connecting the two second abutment portions (523) are orthogonal with each other.

Abstract: An absolute rotary encoder comprises a rotor having a bore passing through the center thereof to receive a shaft therein and arranged rotatably about the shaft and opposite a stator. Tracks are arranged concentrically on the rotor to form a track group. A transmitting winding group is arranged on the stator as capable of flux coupling with the track group. A receiving winding group is arranged on the stator as capable of flux coupling with the track group. Each track in the track group comprises a flux coupling winding that includes linear arc portions having first and second radii and arranged alternately on the rotor and has the shape of a ring continuous about the shaft. At least two tracks in the track group have the linear arc portions different in number from each other.

Abstract: A measuring instrument has a phase signal transmitter that transmits, in accordance with a rotation of the spindle, a phase signal that differs corresponding to the rotation angle of the spindle, and an arithmetic processor that arithmetically processes the phase signal to obtain the absolute position of the spindle. The phase signal transmitter transmits the phase signal at a predetermined pitch. Since the phase signal differs corresponding to the rotation angle of the spindle, a rotation angle of the spindle is uniquely determined by the phase signal. Unlike an increment type measuring instrument, since there is no concern that the signal will be skip-read, the spindle can be rotated at high speed, so that operational performance of the micrometer can be improved. Further, since there is no concern that the signal will be skip-read, the phase signal can be minutely varied with respect to the rotation of the spindle.

Abstract: A rotation transmitter (44) includes a rotor support member (440) provided on an outer circumference of a spindle (2), a rotary piece (45) provided with an engaging portion (46) that is adapted to be engaged with an engaging groove (23), and a coil spring (48) provided between the rotary piece (45) and the rotor support member (440). The rotary piece (45) is supported by the rotor support member (440) in a manner rotatable in a circumferential direction of a rotation shaft (441) provided parallel to the axis of the spindle (2) and the coil spring (48) biases the engaging portion (46) onto the engaging groove (23) via the rotary piece (45).

Abstract: A measuring instrument has a phase signal transmitter (400) that transmits, in accordance with a rotation of the spindle (300), a phase signal that differs corresponding to the rotation angle of the spindle (300), and an arithmetic processor (500) that arithmetically processes the phase signal to obtain the absolute position of the spindle. The phase signal transmitter transmits the phase signal at a predetermined pitch. Since the phase signal differs corresponding to the rotation angle of the spindle (300), a rotation angle of the spindle (300) is uniquely determined by the phase signal. Unlike an increment type measuring instrument, since-there is no concern that the signal will be skip-read, the spindle (300) can be rotated at high speed, so that operational performance of the micrometer (100) can be improved. Further, since there is no concern that the signal will be skip-read, the phase signal can be minutely varied with respect to the rotation of the spindle (300).

Abstract: An absolute rotary encoder comprises a rotor having a bore passing through the center thereof to receive a shaft therein and arranged rotatably about the shaft and opposite a stator. Tracks are arranged concentrically on the rotor to form a track group. A transmitting winding group is arranged on the stator as capable of flux coupling with the track group. A receiving winding group is arranged on the stator as capable of flux coupling with the track group. Each track in the track group comprises a flux coupling winding that includes linear arc portions having first and second radii and arranged alternately on the rotor and has the shape of a ring continuous about the shaft. At least two tracks in the track group have the linear arc portions different in number from each other.

Abstract: An inductive displacement detector of a rotary type is disclosed, which includes a first flux coupling winding and a second flux coupling winding alternately arranged on a rotor. The first flux coupling winding has a line conductor crossed. The second flux coupling winding has a line conductor not crossed. In the first and second flux coupling windings the transmission conductors thereof share a side.

Abstract: An inductive displacement detector of a rotary type is disclosed, which includes a first flux coupling winding and a second flux coupling winding alternately arranged on a rotor. The first flux coupling winding has a line conductor crossed. The second flux coupling winding has a line conductor not crossed. In the first and second flux coupling windings the transmission conductors thereof share a side.