GB474554A - Portable stroboscopic apparatus - Google Patents

Abstract

474,554. Stroboscopes. OEHMICHEN, E. E. Dec. 9, 1936, No. 33865. [Class 97 (i)] Portable stroboscopic apparatus having adjustment of the sharpness and luminosity of vision and binocular vision by observation through regularly spaced openings in the circumference of a disc, to which a mechanical movement imparts a controllable rotary movement, and wherein the speed of the disc is obtained by observing the position of a pointer which moves in front of the divisions of a dial, is characterized in that a governor is operatively associated with the pointer by a lever co-operating with a cam secured to the pointer and carrying a member co-operating with the governor. In the form shown in Fig. 1, the apertures 12, 12<1> register with the openings in the disc 8 shown separately in Fig. 3. Of the four openings 19 one two or all may be exposed by suitably positioning by the knob 13, Fig. 1, the openings 17 of the concentric selector disc 9. The index 10 observed through the window 20 shows the number exposed. The openings can be partially closed by a small relative movement of the discs 8 and 9. The knob 7 locks the disc 8. The speed control device is shown in Fig. 9. The knob 14, Fig. 1, rotates by gearing 50, 51, the axle 48 carrying the pointer 49 moving over the scale 15, and the cam 47 which operates the lever 41, 42 with a friction pad 44 engaging the plate 39 of the governor. The two parts 41, 42 of the intermediate lever are fixed by the screw 52 and are relatively adjustable to give the correct zero setting of the pointer. Figs. 10 and 11 show a device for adjusting the relative settings of the discs 8 and 9 while both are rotating. The pin 56 on the disc 8 projects through an arcuate slot 57 in the disc 9. Two spring loaded plungers in chambers 58, 59 prevent the passage of the pin 56 more than halfway on the slot 57 until sufficient force is applied. Movement of the pointer 64 brakes one of the discs 8, 9, through springs 60, 61. If it is moved to position 2 and released the selector disc 8 is retarded and the pin 56 moves forward to the spring plungers to give position 2 for the disc 9. If pointer 64 is moved to 4 the selector disc is braked hard and the pin 56 forces the spring plungers apart to give position 4. To return to position 1 the pointer 64 is placed on 1, when the disc 8 is braked and the disc 9 moves forward by inertia. The spring plungers may be shaped to facilitate the return movement. The Specification also contains a description of a movable masking plate with narrow slits to limit the size of the observation apertures 12, 12<1> and outlines a differential arrangement with two stroboscopic discs rotating at different speeds. A discussion is also given of the appearance of a periodic motion when observed stroboscopically with a frequency which is a multiple or sub-multiple of that of the observed object. Specification 114,830 is referred to.