Patent GB-987619-A (GB)
Title: Improvements in and relating to grid winding machines for therminoic valves
IPC: H01J19/00
Filed: 1963-05-24
Abstract: 987,619. Winding grids for thermionic valves. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. May 24, 1963 [May 28, 1962], No. 20796/63. Heading B3E. [Also in Divisions G1 and H2] A grid winding machine for tensioned grids for use in thermionic valves, regions of differing pitch being wound, includes a wire guide on a rotating pitch-setting spindle, a winding spindle and control members by which the difference between the speeds of rotation of the pitchsetting spindle and the winding spindle can be smoothly varied during the winding operation. Grid wire 11 from a reel 9 passes over a guide sleeve 13 fixed on a rotating spindle 5 and formed with a helical groove which causes the wire to travel from one end of the sleeve to the other so as to wind helically on a grid frame 7 on a rotating winding spindle 3. To vary the pitch of the winding on the frame 7 the relative rotational speeds of the spindles 5 and 3 is varied. In one embodiment, Fig. 2, the spindle 3 is driven by a motor 15 which also drives, through a shaft 19, a friction wheel 25 engaging a disc 27 fixed on the pitch setting spindle 5. The motor 15 also rotates, through a shaft 21, a cam 29 which rocks a lever 33 to raise and lower the friction wheel 25 thus varying the transmission ratio of the wheel 25 and disc 27 and thus the speed of the spindle 5. In another embodiment, Fig. 3, the spindles 3 and 5 are driven by synchronous motors 37 and 37a to which control currents are fed from an electrical control device 41 via amplifiers 39 and 39a. The control currents may be derived from a recording tape having one track with a constant frequency to feed the motor 37 of the spindle 3 with a control current of constant frequency and the other track having different frequencies in accordance with the winding programme to supply control currents of different frequencies to the motor 37a of the spindle 5. In a further embodiment, Fig. 5, a generator produces a large number of control currents of different frequencies to be fed to the motor 37a. The generator may comprise a disc 53, formed with concentric circles 55 of holes 57, rotated between a row of lamps 59, one for each circle of holes, and a row of photocells 61. One terminal of each photo-cell is connected to each amplifier 39, 39a and the other terminal to a setting panel 63 in which pins 69 connected to selector contacts 65 are inserted. The pulses produced by each circle of holes produce an alternating current of a frequency corresponding to the number of holes in the circle and according to which contact 65 a wiper 71 contacts so current of a certain frequency is fed to the amplifier 39a and thus to the synchronous motor 37a. A pulse generator 73 operated by a cam on the winding spindle 3 supplies pulses to a counting and controlling device 75 which, through relays, moves the wiper 71 from one contact 65 to another, according to a selected programme, thus to vary the speed of the motor 37a. Alternatively, Fig. 6, the generator may comprise a disc 81 rotated between stationary discs 79, discs 79 and 81 having iron pins 86, 87 thereon arranged in aligned concentric circles. The disc 81 consists of an axially magnetized permanent magnet with iron sheets on its faces. The discs 79 are of sheet iron and all the pins 86 of the separate circles are provided with windings 89 connected consecutively in each circle and the beginning and ends of the wires for each circle are connected to wires 91, 95, the wires 91 being connected to an earth connected choke 93 and wires 95 to earth-connected resistors 97 and to control current leads taken to the switching panel 63. As the disc 81 rotates the magnet poles formed by the pins 87 generate currents in the wires wound around the pins 86, the frequency of such currents corresponding to the number of pins in the particular circle of pins. Acknowledged prior art includes the use of a guide sleeve 11 having a helical groove of differing pitches and the use of a wire guide moved parallel to the winding spindle by a series of pitches controlled by a punched strip of sound recording tape.