GB881903A - Automatic pinspotter control mechanism - Google Patents

Abstract

881,903. Skittle alleys. AMERICAN MACHINE & FOUNDRY CO. Feb. 26, 1958 [April 4, 1957], No. 6252/58. Class 132(2) [Also in Group XL(b)] An automatic bowling pin-setting machine includes a detector for sensing the wobbling and the presence of each of the pins and for controlling the setting and scoring operations of the game. The wobbling produces an amplitude-modulated signal whereas the presence or absence of a pin varies the amplitude level of the signal. The detector may be photo-electric; or capacity or induction effects produced between capacitors or coils respectively in the pins and the alley floor may be used. Light reflected by pins 12 (Fig. 2) are sensed by a pinhole camera 10, one for each pin. Each camera 10 has two independent pin-hole plates one focusing the image of the pin through a saw-tooth mask 24 (Fig. 4, not shown) and the other focusing the general background illumination. A photo-multiplier to the rear of each camera face produces a signal, the two being fed to a difference circuit 32 giving the A.M. wobble signal and the LM presence signal. Presence amplifier 33 filters out the wobble signal and feeds the resultant to a pin presence relay 35. In a parallel circuit a low pass filter 34 allows the passage of the wobble signals through amplifier 36 and limiter 38 to a sharp cut-off amplifier 40 and controls a relay 42 which operates the pin-spotter when the relay is energized, i.e. when the wobble has ceased. The circuit diagram of the elements of Fig. 2 are given in Fig. 4 (not shown). Fig. 11 shows an impedance detector comprising a floor coil tuned by a capacitor and a coil 1002 in the base of the pin but protected by a thin insulating layer from wear and tear. A carrier signal of between 100 kc. and 2 mc. fed to the floor coil is modulated by pin wobble and increased in amplitude when the pin is knocked over. A similar capacitative transducer may be used (Fig. 13, not shown). Gutter ball switches are provided (Fig. 16, not shown).