Transducer positioning mechanism

Claim 2

In a system for positioning a transducer over a selected recording track of a peripheral magnetic disc store, the combination including: means for storing the desired position of the transducer and means for storing the actual position of the transducer; means for comparing the actual and desired positions, said comparing means being connected to said actual and desired position storing means and producing a fast and slow positioning signals depending on the magnitude of the difference between the desired and actual positions and further producing a direction signal; pulse generator means, responsive to said slow and fast signals, for producing pulses of relatively low or high frequencies, an output of said pulse generator being connected to said actual position storing means; a bi-directional counter, connected to an output of the pulse generator, for counting the pulse produced, the direction of counting being controlled by said direction signal; a stepping motor, connected to an output of the bi-directional counter for positioning said transducer; an odd-even counter means, connected to the output of the pulse generator for recording whether the number of pulses produced by said generator is odd or even; a fine positioning device, respoNsive to said odd-even counter, for positioning said transducer.

Claim 3

The system according to claim 1, wherein said fine positioning device includes a rack fast with said transducer, at least two stop latches having a fixed position with respect to the direction of movement of said transducer and movable in a transverse direction to engage with said rack, the pitch of said rack being equivalent to an even multiple of the radial distance between two recording tracks while the pitch between said two latches is equivalent to an odd multiple of the radial distance between two recording tracks, said latches being selectively activated by said odd-even counter means.

Claim 4

The system according to claim 1, wherein said pulse generator comprises a transistor connected across a bias voltage in parallel with a first and a second branch, said first branch including a resistor R1 and a capacitor C1 while said second branch includes a resistor R2 and a capacitor C2, C1 being connected in parallel with switch V1 and C2 being connected in parallel with switch V2 and resistor R3, R3 and V2 being in series, the points between R1-C1 and R2-C2 being connected, the opening of V1 causing low frequency oscillations, the opening of both V1 and V2 causing high frequency oscillations.

Claim 5

Mechanism for positioning the transducers of a disc store, comprising a coarse positioning device to control the shifting of said transducers in a radial direction with respect to said discs, and a fine positioning device to control in a fine manner the positioning of said transducers over a selected track, said second positioning device functioning as a locating device and being constituted by a rack fast with said transducers, at least one stop push rod having a wedge-shaped end fixed position with respect to the direction of shifting of said transducers and an electromagnet for moving said rod in a transverse direction to engage said wedge-shaped end thereof with that space of said rack which is brought into correspondence therewith by said coarse positioning device, two transverse leaf springs supporting each push rod, a lever fast with the armature of said electromagnet and opposing a first spring to control said push rod, said armature in the condition of energization of the electromagnet being maintained in a first position by overcoming the action of the second spring which tends to retain it in a second position corresponding to the de-energization of the electromagnet, said second spring being adapted to exert a resilient load greater than that of said first spring, so that when the command of said fine position device effects the de-energization of said electromagnet said second spring, by shifting said armature towards the second position, releases said rod from the control of said lever and permits said first spring to act on the mass only of said rod and cause it to engage with said rack.

Claim 6

Mechanism for positioning the transducers of a disc store, comprising a coarse positioning device to control the shifting of said transducers in a radial direction with respect to said discs, and a fine positioning device to control in a fine manner the positioning of said transducers over a selected track, said second positioning device functioning as a locating device and being constituted by a rack fast with said transducers, at least one stop push rod having a wedge-shaped end fixed position with respect to the direction of shifting of said transducers and an electromagnet for moving said rod in a transverse direction to engage said wedge-shaped end thereof with that space of said rack which is brought into correspondence therewith by said coarse positioning device, two transverse leaf springs supporting each push rod, a lever fast with the armature of said electromagnet and opposing a first spring to control said push rod, said armature in the condition of energization of the electromagnet being maintained in a first position by overcoming the action of the second spring which tends to retain it in a second position corresponding to the de-energization of the electromagnet, said second spring being adapted to exert a resilient load greater than that of said first spring, so that when the command of said fine position device effects the de-energization of said electromagnet said second spring, by shifting said armature towards the second position, releases said rod from the control of said lever and permits said first spring to act on the mass only of said rod and cause it to engage with said rack.