ES341485A1 - Improvements in and relating to Measuring Apparatus - Google Patents

Abstract

The distance travelled by one body relative to another is measured by a metering wheel 20, Fig. 2, on the. first body frictionally engaged with a surface 14 of the second, the metering wheel driving an output shaft 28 carrying means to generate incremental:pulses which are used to drive a visual display unit, located at a distance, indicating the number of rotations of the metering wheel and fractions thereof. The output shaft 28 may be geared to turn 60 times to each revolution of the metering wheel. The output shaft may carry a perforated disc co-operating with spaced photo-cells to provide two waveforms displaced by 90 degrees. These are squared and applied to gates to produce forward and backward signals on separate leads for application to a counter. The counter is connected to the visual display. Indicating dials are also provided on the body 12 to indicate the positions of the shafts 22 and 28. In another form the increment pulses may be derived from a ten facet mirror 95, Fig. 8, which sweeps a beam of light over ten photo-cells arranged in an arc. Each photo-cell is composed of four parts which are differently masked so that as the beam crosses each photo-cell four different amplitudes are obtained in succession. From the order of arrival of these signals the direction of motion can be ascertained to control a counter as before. The direction discriminator is controlled by a switch so that " forwards " can be in either direction as selected. In another form the rotating mirror has 100 facets and the beam sweeps over two photo-cells which are staggered so that the direction can be determined from the signal sequence. Alternatively there may be a single mirror on the end of the shaft 28, an aligned lamp and a ring of 100 photo-cells which may be masked as above to obtain an indication of direction. In another modification, a contact disc pick-up brushes provides increment and direction signals. The signal generating means may be on another shaft remote from the body 12, the remote shaft being driven from shaft 28 through a servo-system with a reversing switch. The measuring system may be embodied in a control system for a machine tool in which values read from a punched tape are compared with the contents of the counter and a leadscrew motor driven to achieve equality.