Storage system having a head assembly for reading and writing on a record member having a touch indicator circuit

Claim 2

A storage system comprising: a magnetic record member having an electrically conductive surface; a magnetic transducer assembly for reading and writing on said record member and having an electrically conductive surface, said surfaces being normally separated by a dielectric gap; a source of electrical energy for establishing between said surfaces a potential difference continuously greater than a predetermined value while there is a normal gap therebetween; and a differential input comparator responsive to the existence across the gap of a potential difference having a value less than the predetermined value for generating a signal which indicates that electrical contact has occurred between said surfaces.

Claim 3

A storage system according to claim 1 comprising an impedance connected in series between the potential source and at least one of said surfaces for limiting the current flow in the event of a contact between said surfaces.

Claim 4

A storage system according to claim 1 wherein said comparator has a first input coupled to one of said conductive surfaces and a second input coupled to a reference potential corresponding to the potential at which electrical contact is to be indicated.

Claim 5

The storage system according to claim 1 in which the magnetic record member is a rotatable magnetic disk.

Claim 6

A storage system according to claim comprising: bistable means for storing a signal indicating a touch in response to said signal from said comparator.

Claim 7

A storage system according to claim 5 comprising a delay circuit coupling the comparator to the bistable means to prevent the bistable means from storing signals caused by a spurious signal.

Claim 8

A storage system according to claim 6, comprising: means for coupling the output of the bistable means to an input of the comparator for maintaining said output signal from said comparator after said bistable means stores such signal.

Claim 9

The storage system according to claim 5 comprising circuit means coupled in series circuit relation between an input to the differential comparator and one of said electrical surfaces to delay the indication by the comparator thereby preventing the bistable means from storing signals caused by a spurious signal.

Claim 10

A storage system comprising: a rotatable magnetic disk having an electrically conductive surface; an assembly constructed for floating on a film of air adjacent to the moving disk and having an electrically conductive surface and supporting a magnetic transducer in proximity with the disk; a substantially constant voltage source and resistor electrically coupled In series circuit relation with said conductive surfaces; a differential input comparator circuit having an input electrically coupled to one of the electrically conductive surfaces for generating a first signal which indicates that electrical conduction has occurred between said surfaces; a delay circuit responsive to said first signal for generating a second signal after the first signal has been present for a prescribed length of time; and bistable circuit means responsive to the second signal for generating and storing a third signal indicating a touch between said surfaces.

Claim 11

A storage system comprising: a rotatable magnetic disk having an electrically conductive surface; an assembly constructed for floating on a film of air adjacent to the moving disk and having an electrically conductive surface and supporting a magnetic transducer in proximity with the disk; a substantially constant voltage source and resistor electrically coupled In series circuit relation with said conductive surfaces; a differential input comparator circuit having an input electrically coupled to one of the electrically conductive surfaces for generating a first signal which indicates that electrical conduction has occurred between said surfaces; a delay circuit responsive to said first signal for generating a second signal after the first signal has been present for a prescribed length of time; and bistable circuit means responsive to the second signal for generating and storing a third signal indicating a touch between said surfaces.

Claim 12

A storage system comprising: a record member having a magnetic recording surface; a magnetic head assembly for reading and writing on said recording surface during relative movement therebetween, said record member and head having a conductive surface on each which make electrical contact in the event of contact between record member and head assembly; a source of voltage; a circuit for coupling the source of voltage across said conductive surfaces and including an impedance connected in series circuit relation with the conductive surfaces and any source of potential for limiting the flow of current between said conductive surfaces in the event of a contact therebetween; and a differential input comparator circuit having a first input coupled to one of said conductive surfaces and a second input coupled to a reference potential, the comparator circuit being responsive to the existence of a predetermined potential at said first input with respect to said reference potential for providing a predetermined output signal which indicates contact between said conductive surfaces.

Claim 13

A storage system comprising: a record member having a magnetic recording surface; a magnetic head assembly for reading and writing on said recording surface during relative movement therebetween, said record member and head having a conductive surface on each which make electrical contact in the event of contact between record member and head assembly; a source of voltage; a circuit for coupling the source of voltage across said conductive surfaces and including an impedance connected in series circuit relation with the conductive surfaces and any source of potential for limiting the flow of current between said conductive surfaces in the event of a contact therebetween; and a differential input comparator circuit having a first input coupled to one of said conductive surfaces and a second input coupled to a reference potential, the comparator circuit being responsive to the existence of a predetermined potential at said first input with respect to said reference potential for providing a predetermined output signal which indicates contact between said conductive surfaces.

Claim 14

A storage system according to claim 10 wherein the source of voltage supplies a substantially constant voltage and wherein said impedance comprises a resistor.

Claim 15

A storage system according to claim 10, comprising a feedback circuit coupled between the output of said differential input comparator circuit and one of said inputs to said differential comparator for maintaining said predetermined output signal even after the termination of contact between said conductive surfaces.

Claim 16

A storage system according to claim 12, wherein the feedback circuit comprises a delay circuit which delays application of the feedback signal long enough to insure it is not caused by a spurious signal.

Claim 17

A storage system according to claim 12 wherein said feedback circuit comprises a bistable circuit having an input coupled to the output of said delay circuit and an output coupled to one of the inputs of said differential comparator circuit.

Claim 18

A storage system according to claim 14, wherein the outputs of said bistable circuit is coupled to the second input of said differential input comparator circuit.

Claim 19

A storage system according to claim 14 comprising a voltage divider coupled to the second input of said differential input comparator circuit for applying a reference potential thereto.

Claim 20

A storage system comprising: a magnetic record member having an electrically conductive surface; a magnetic transducer assembly for reading and writing on said record member and having an electrically conductive surface, said surfaces being normally separated by a dielectric gap; a source of electrical energy for establishing a potential difference greater than a predetermined value between said surfaces while there is a normal gap between said surfaces and comprising means for causing said potential difference to change to a lower value when the gap is abnormally small; a differential input comparator; a source of a substantially constant reference potential for indicating a normal gap; and means for simultaneously coupling the instantaneous signals being formed by said reference potential and one of said surfaces to different inputs of said comparator thereby causing the comparator to generate a first signal for a normal gap and a second signaL indicating an abnormally small gap when the potential difference between said surfaces changes to said lower value due to an abnormally small gap.

Claim 21

A storage system comprising: a magnetic record member having an electrically conductive surface; a magnetic transducer assembly for reading and writing on said record member and having an electrically conductive surface, said surfaces being normally separated by a dielectric gap; a source of electrical energy for establishing a potential difference greater than a predetermined value between said surfaces while there is a normal gap between said surfaces and comprising means for causing said potential difference to change to a lower value when the gap is abnormally small; a differential input comparator; a source of a substantially constant reference potential for indicating a normal gap; and means for simultaneously coupling the instantaneous signals being formed by said reference potential and one of said surfaces to different inputs of said comparator thereby causing the comparator to generate a first signal for a normal gap and a second signaL indicating an abnormally small gap when the potential difference between said surfaces changes to said lower value due to an abnormally small gap.

Claim 22

A storage system according to claim 17, wherein said means for causing said potential difference to change comprises means for coupling the source of electrical energy across said surfaces and an impedance coupled in between said one surface and said source of electrical energy.