US 4,063,293 A · Magnetic head switching matrix with bi-directional current capability

Abstract

A magnetic head switching matrix selectively couples a plurality of balanced read-write heads to the output of a write amplifier and to the input of a read amplifier. Constant current supplies apply equal constant currents to a pair of write data lines connected to the write amplifier output and two further constant current supplies apply equal constant currents to two read data lines connected to the read amplifier input. The two coils of each head are coupled to the write data lines through two matched diodes respectively and are similarly coupled to the read data lines through another pair of matched diodes respectively. The center tap of each head is coupled to write and read reference voltage sources through respective diodes as well as being coupled to a read-write control voltage source. A head write selection current supply applies a selection current to the center tap of a selected head for writing purposes and a head read selection current supply applies a current to the center tap of a selected head for reading purposes.

Drawings

Claims17

Dependent claims

A switching circuit for selectively coupling amplifier means to a plurality of magnetic heads, each said head including two serially connected coils with a center tap therebetween, comprising

first and second data line means coupled to said amplifier means,
first and second constant current supply means coupled to said first and second data line means respectively for inducing substantially equal constant currents therein,
first and second diode means associated with each said head coupling said two coils thereof to said first and second data line means respectively,
reference voltage source means,
third diode means associated with each said head coupling said center tap thereof to said reference voltage source means,
control voltage source means coupled to said center tap of each said head,
head selection current supply means for providing a head selection current to select a head, and
head selection means for selectively coupling said head selection current to the center tap of said selected head whereby said substantially equal constant currents flow through said first and second diode means associated with said selected head,
said reference voltage source means and said control voltage source means providing voltages for reverse biasing said diode means associated with the non-selected heads.

6 more elements

A switching circuit for a plurality of magnetic read-write heads for selectively coupling each said head to write amplifier means for applying bi-directional write currents thereto and for selectively coupling each said head to read amplifier means for receiving bi-directional read currents therefrom, each said head including two serially connected coils with a center tap therebetween, comprising

first and second write data lines coupled to the output of said write amplifier means,
first and second constant current supply means coupled to said first and second write data lines respectively for inducing substantially equal write constant currents therein,
first and second diode means associated with each said head coupling said two coils thereof to said first and second write data lines respectively,
first and second read data lines coupled to the input of said read amplifier means,
third and fourth constant current supply means coupled to said first and second read data lines respectively for inducing substantially equal read constant currents therein,
third and fourth diode means associated with each said head coupling said two coils thereof to said first and second read data lines respectively,
write and read reference voltage source means,
fifth and sixth diode means associated with each said head coupling said center tap thereof to said write and read reference voltage source means respectively,
control voltage source means coupled to said center tap of each said head,
write head selection current supply means for providing a write head selection current to select a head for writing,
write head selection means for selectively coupling said write head selection current to the center tap of said selected head whereby said substantially equal write constant currents flow through said first and second diode means associated with said selected head,
read head selection current supply means for providing a read head selection current to select a head for reading,
read head selection means for selectively coupling said read head selection current to the center tap of said selected head whereby said substantially equal read constant currents flow through said third and fourth diode means associated with said selected head,
said write and read reference voltage source means and said control voltage source means providing voltages for reverse biasing said diode means associated with the non-selected heads, for reverse biasing said third and fourth diode means of said selected head when said head is selected for writing and for reverse biasing said first and second diode means of said selected head when said head is selected for reading.

11 more elements

Dependencies are inferred from the claim text.

Description4,293 words

Summary396 words

#1. Field of the Invention

#The invention relates to the field of magnetic head switching matrices, particularly with regard to providing bi-directional current capabilities.

#2. Description of the Prior Art

Brief description of the drawings20 words

#The sole FIGURE is a schematic circuit diagram of a head switching matrix configured in accordance with the present invention.

Detailed description3,877 words

#Referring to the sole FIGURE, a schematic circuit diagram of a head switching matrix configured in accordance with the present invention is illustrated. The matrix is utilized to connect the output of a write amplifier 10 and the input of a read amplifier 11 to a plurality of magnetic read-write heads, two of which being illustrated at 12 and 12'. The write amplifier 10 is of the conventional type utilized for providing signals to magnetic heads for recording data on the magnetic medium of the system. The amplifier 10 has an input 14 for receiving the signals to be recorded which preferably comprise bi-directional data signals as well as a high frequency bias signal for linearizing the medium. The read amplifier 11 is of the low noise high gain, a.c. coupled type utilized for providing data signals read from the medium by the magnetic heads 12 and 12', the data signals being provided at an output 15 of the read amplifier 11.

#The output terminals from the write amplifier 10 are connected respectively to write data bus lines 16 and 17 and the input terminals to the read amplifier 11 are connected respectively to read data bus lines 20 and 21. Constant current supplies 22 and 23 inject equal constant currents I.sub.W into the write data bus lines 16 and 17 respectively and constant current supplies 24 and 25 draw equal constant currents I.sub.R from the read data bus lines 20 and 21 respectively. The constant currents I.sub.W provided by the supplies 22 and 23 are equal to each other and are maintained constant throughout the head selection and read-write modes of the matrix. Similarly, the constant currents I.sub.R provided by the supplies 24 and 25 are equal to each other and are maintained constant during the various operating modes of the matrix. The current I.sub.W is selected to be equal to or greater than the peak current expected from the write amplifier 10. The current I.sub.R is selected at a few tens of milliamperes to minimize noise. I.sub.R is generally selected to maintain a value between 10 and 50 milliamperes.

#Although the elements 22-25 have been generically described as current supplies, it will be appreciated that in the specific embodiment illustrated the elements 22 and 23 are specifically selected as current sources whereas the elements 24 and 25 are specifically selected as current sinks.

Facts

Application

05/677,957Filed 19 Apr 1976

Granted

13 Dec 1977

Term ended

13 Dec 1994

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

G11B 15/12
Control of operating function, e.g. switching from recording to reproducing: masking of heads; circuits for Selecting or switching of heads…
G11B 5/09
Recording, reproducing, or erasing methods; Read, write or erase circuits therefor: digital recording
G11B
Information storage based on relative movement between record carrier and transducer

Magnetic head switching matrix with bi-directional current capability

Life of this patent

Magnetic head switching matrix with bi-directional current capability

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims17

Description4,293 words

Drawings

Classification3 codes

Life of this patent

Description4,293 words