Abstract: A camera lens barrel having a first grouped lens, a movable second grouped lens for variable magnification, a third grouped lens, and a fourth grouped lens, which are respectively arranged along an optical axis, and accommodating a drive system for the first to fourth lenses. The camera lens barrel is provided with a stepping motor, a control device capable of respectively carrying out in a low speed drive mode at least micro step drive control and pulse drive control of the stepping motor, and a moving mechanism for converting rotation of the stepping motor into movement of the second grouped lens along the optical axis. The control device carries out position control of the second grouped lens according to a control quantity of the stepping motor. As the stepping motor is driven under the micro step drive control, the generation of noise and vibration can be greatly suppressed as compared with a conventional lens barrel employing a DC motor as a drive source.

Abstract: A position detecting method for detecting a position of a moving object such as a bearing or a lens by capturing a plurality of repetitive periodic waveforms coming from a position sensor and performing data processing on the captured waveforms. The method comprises the steps of moving the moving object by more than one period of the waveforms, obtaining a maximum value and a minimum value of the waveforms, obtaining an offset value and a gain of the waveforms based on the maximum value and the minimum value, correcting a gain and an offset value of data based on the obtained offset value and the gain of the waveforms to create corrected data, and processing the corrected data to detect the position of the moving object.

Abstract: A position detecting apparatus with a sampling function, comprises a waveform generator for generating repetitive periodic waveforms in relation to a moving object to be measured. A processor samples the output of the waveform generator and, after digitizing the same, processes the digital data to detect the position of the object. The processor first estimates the current position from the data obtained in the preceding detection and then determines the current position on the basis of the estimated position. The apparatus can be incorporated in a system for driving an optical unit in a video camera, wherein the object to be measured is a moving focus lens member and is actuated by a direct drive motor.

Abstract: An MR position detecting device according to the present invention comprises a magnet having magnetic poles alternately magnetized at predetermined intervals, a magnetoresistive element having magneto-detectors for a plurality of phases successively disposed a predetermined distance apart, with a pair of the magneto-detectors provided for each phase. The pair of magneto-detectors for each phase change their resistance values in response to the magnetic field of the magnet, are disposed half the formed magnetic pole width, in substance, apart, and are applied with voltage at both ends of a series connection thereof so as to output a signal from the middle point of the connection. A signal processing circuit defects a change in relative position between the magnetoresistive element and magnet on the basis of a signal obtained from the outputs of the pairs of magneto-detectors for the respective phases of the magnetoresistive element therefore, the device may detect position with high resolution and accuracy.

Abstract: There are provided a method and an apparatus for absolute position detection, in which position detection is performed with high accuracy by interpolation between feedback pulses generated as an object of position detection moves, and the power-on command displacement can be calculated with high accuracy, the method and the apparatus entailing only small electric power consumption. A stored value in an absolute counter (2), which is indicative of an approximate absolute position of an object of position detection, is updated each time a feedback pulse is generated from a feedback pulse generating circuit (1), and is retentively stored in the counter even after the power is turned off. As the object of position detection moves, moreover, the count value of interpolation pulses, generated during the time interval which elapses from the instant that the power is turned on again until the first one of the feedback pulses is generated, is temporarily stored in a correction counter (5).