Digital incremental magnetic tape recorder

Claim 2

An incremental recorder for recording input digital data comprising: a stepper motor operatively coupled to a capstan for incrementally advancing a magnetic recording medium; means for detecting displacement of said magnetic recording medium through a predetermined distance, said means comprising: i. an annular, very low inertia disc having spaced signal producing portions coupled to said stepper motor and rotating in accordance therewith, said annular disc having adjacent peripheral sections of substantially different magnetic permeabilities, and ii. detecting means responsive to said signal producing portions to provide an output control signal responsive to a predetermined rotation of said disc, said detecting means including means for establishing a magnetic flux field normal to the periphery of said annular disc, rotation of said disc through said flux field causing said flux field to increase as a peripheral section of said disc having a high magnetic permeability enters said flux field, said flux field being a maximum when said high magnetic permeability peripheral section reaches a predetermined location within said flux field, said detecting means also including a pickoff means susceptible to the rate of change of flux in said magnetic flux field for generating said output signal having an increasing amplitude as said flux increases and returning to zero when said flux reaches a maximum, said return to zero of said output signal being coincident with said disc reaching a predetermined location within said flux field; means coupled to said output signal for providing a write control signal substantially insensitive to noise and coincident with a predetermined spatial alignment of a signal producing portion of said disc and said detecting means; and recording means coupled to said input digital data and responsive to said output control signal for recording said data on said recording medium when said medium has been displaced through said predetermined distance.

Claim 3

The incremental recorder described in claim 1 wherein said means coupled to said output signal for providing a write control signal generates the leading edge of said write control signal when the amplitude of said output signal exceeds a predetermined minimum and causes the trailing edge to occur when said output signal exceeds a predetermined minimum and causes the trailing edge to occur when said output signal returns to zero, said trailing edge of said write control signal being coincident with said high magnetic permeability peripheral section of said disc reaching a predetermined location with said flux field and wherein said recording means records data on said recording medium when said trailing edge of said write control signal occurs.

Claim 4

The incremental recorder described in claim 1 wherein said annular disc is coupled to said stepper motor so that a high magnetic permeability section of said disc will reach said predetermined location in said flux field when said stepper motor has completed a predetermined portion of its incremental movement. 4. An apparatus having applied step command and input data for recording said data at precise intervals on a recording medium advanced in response to said step command comprising: means operatively coupled to said recording medium and having said step command as an input for advancing said recording medium an incremental distance in response to said step command; displacement indicating means for generating a write control signal output after said recording medium has been advanced a predetermined distance, said displacement indicating means comprising: i. an annular disc fixedly attached to the shaft of said means operatively coupled to said recording medium having an angular displacement proportionate to the linear displacement of said recording medium and also having adjacent peripheral sections of different magnetic permeability, and ii. detecting means having a fixed position adjacent said disc and responsive to the differences in magnetic permeability between peripheral sections of said disc for generating an electrical output signal when said disc rotates through a predetermined angle, said detecting means comprising: a. means for generating a magnetic flux field normal to said disc at a point proximate its periphery, rotation of said disc resulting in said peripheral sections of said disc passing through said field changing said flux; and b. pickoff means susceptible to said flux change for generating an electrical pickoff signal increasing to a maximum as a peripheral section of high magnetic permeability enters said flux field and returning to zero as said peripheral section reaches a predetermined location within said flux field; and recording means having said input data and said write control signal as an input for recording said data on said recording medium when said write control signal is generated. 5. The apparatus of claim 4 wherein said detecting means further includes a pulse shaping means having said electrical pickoff signal as an input and generating a pulse output having a leading edge which is initiated when said pickoff signal exceeds a predetermined magnitude and having a trailing edge occurring when said pickoff signal becomes approximately zero.

Claim 5

The apparatus of claim 5 wherein said electrical output signal returns to zero from a maximum when said disc rotates through an angle proportionate to said recording medium advancing a predetermined portion of its incremental distance.

Claim 6

The apparatus of claim 5 wherein said recording means comprises: a coincidence gate having as an input said pulse and said input data, said gate generating an output when said trailing edge of said pulse occurs if a signal is present on said data input; a toggle flip-flop having the output generated by said coincidence gate connected as a toggle input such that the flip-flop will change state for each toggle input received; and, a recording head adjacent said recording medium having the output of said toggle flip-flop as an input for recording a data bit on said recording medium each time said toggle flip-flop changes state.