| 摘要 |
PURPOSE:To select a frequency responsiveness most suitable for the movement speed by controlling the band width of a frequency of a filter means in accordance with the movement speed of a moving object. CONSTITUTION:A detecting means 4 detects the luminous flux, which passes light-transmissive parts of a main scale 2a and an index scale 3a in accordance with the rotation of a rotating disk 2, out of the luminous flux from a light source 1. At such a time, an analog signal having a frequency corresponding to the rotative speed of the disk 2 is outputted from the means 4 by the luminous flux from the light source 1. The current based on the analog signal from the means 4 is converted to a voltage by a converter 5 and is inputted to a filter means 11. This means 11 consists of a specific LPF or the like whose frequency band width is selected by the input signal from a selecting means 10. The selecting means 10 selects the frequency band width of the means 11 in accordance with the rotational speed of the disk 2 by the inputs from control signal terminals 12 and 13. |
