Patent GB-738936-A (GB)
Title: Improvements in and relating to devices for continually determining the values of a variable measured quantity
Inventor: SEGEBADEN ERNST SIGURD DETLOF
IPC: G06G7/78
Filed: 1953-10-15
Abstract: 738,936. Calculating-apparatus. ARENCO AKTIEBOLAG. Oct. 15, 1953, No. 28508/53. Class 106 (1). Apparatus for calculating the instantaneous value and rate of change of a variable, a time graph of which is being continuously recorded, comprises a change-speed device 77 arranged to turn an inclination indicator A into correspondence with the average inclination of the most recent part of the graph, the change-speed device 77 being connected to a value integrator 9, which causes a projector 45, for throwing an image of the graph R on to a semi-transparent screen 68, to be displaced in the same direction as the stylus 14 drawing the graph R but at such a speed that the image P of the point being recorded remains stationary. A rod 41 slides axiatly in accordance with the altitude of a target and the stylus 14 scratches the graph R on the surface I of a band 16 which is coated with a non-drying paint and driven at constant speed round rollers 17, a roller 118, e.g. of rubber, erasing the graph. A mirror 65 inside the band 16 reflects light from a source 67 through the scratched graph R to a projector 45 which throws an enlarged image of the graph on a semi-transparent screen 68, while a projector device 73 throws an image of a transparent slit A in an opaque disc 4 which is rotated to follow the inclination of the graph image by turning a handle 10. The handle 10 controls the sliding movement of a yoke 77 and shifts the points of contact of a constant-speed wheel 92 with sunwheels 86 of a differential gear 90 whose planet carrier then turns a shaft 91 in a direction and at a speed corresponding with the alteration in the rate of change of altitude signified by the altered inclination of the graph. The shaft 91 then drives through a gear train a gear-wheel 57 which through further trains drives lead-screws 70, 71 to shift the mirror 65 and projector 45 at suitable speeds corresponding with the changing altitude to keep the foot P of the image of the graph R stationary and coincident with the image of the centre of disc 4. The amount the handle 10 has to be turned is a measure of the rate of change of altitude h<SP>1</SP> which is indicated by a register 106 and the integration effected by the differential gear 9 is a measure of the altitude h which is indicated by a counter 104 driven from the shaft 91 through gear-wheel 57 and a further gear train. In the application of the invention to gunnery, information relating to the position of the target is received from an observation post in the form of rotary movements corresponding to the changing polar coordinates inclined range A1, elevation angle # and azimuth angle α and is fed to a ballistic instrument in the form of rotary movements corresponding to the changing cartesian coordinates h, Ahx, Ahy and their derivatives h<SP>1</SP>, Ahxl, Ahy<SP>1</SP>. As shown, the variables # and A1 are introduced at 43 and 110 to a resolving device which positions a rotatable rack 46 hinged at 47 to guide-rods 49, 52 so that the axial position of a rod 49 represents h and of 52, Ah, i.e. the horizontal projection of A1. a and Ah are then introduced to another resolving device to produce Ahx and Ahy from which their derivatives are obtained in the same way as h from h<SP>1</SP>. Various errors due to time delays may be corrected by turning a handle 15 for adjusting a sun-wheel of a differential gear 8 introduced in the gear train between shaft 91 and gear-wheel 57. An automatic follow-up device may be introduced in the form of a reversible motor 39 driving a sun-wheel of a further differential gear 60 in the same gear train and controlled by a contact 35 moving with the stylus rod 41 between adjustable contacts carried by a block 36 adjusted by a lead-screw 61 also driven from the gear-wheel 57. Other errors may be corrected by adjusting the projector 73 through a handle 135. Should the stylus 14 move beyond the edges of the band 16 a clutch 40 would cut off the drive between the shaft 91 and gear-wheel 57, production of the stationary graph line image would cease and the target would be beyond firing range, but to facilitate operating again when the target returns within range, a series of styli may be carried by the rod 41 operating successively to produce graphs moving across the screen which could be followed approximately by the inclination indicator 4. Photo-electric means may be used automatically to adjust the projector 45 and indicator 4.