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US 5,291,069 AGranted
Bipolar H write driver
AssigneeInternational Business Machines Corporation
InventorsGary F. Gooding, Larry L. Tretter
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AssigneeInternational Business Machines Corporation
InventorsGary F. Gooding, Larry L. Tretter
Estimating the term…
An improved driver design including a plurality of NPN bipolar driver transistors connected in an H configuration including at least one bipolar upper drive transistor. A novel circuit is included for driving the upper NPN bipolar driver transistor. In a particular implementation, the circuit for driving the upper bipolar drive transistor is adapted to sense the output of the drive transistor and regulate a voltage at the input thereof in response thereto to keep the drive transistor out of saturation. Thus, power dissipation is minimized by using an H configuration and high speed is afforded by using bipolar drive transistors and by keeping the drive transistors out of saturation.
A driver circuit comprising:
A driver circuit comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
Connected to both load terminals: each output circuit comprising more than one controlled bipolar transistor
The output circuit comprising more than one controlled field-effect transistor: in a symmetrical configuration
Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00: means reducing energy…
Pulse technique
Term ended 15 Dec 2012 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to drive circuits. More specifically, the present invention relates to drive circuits used for write heads for tape recorders and the like.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
FIG. 1 is a schematic diagram of a bipolar write driver constructed in accordance with conventional teachings.
FIG. 2 is a schematic diagram of a CMOS "H" write driver architecture.
FIG. 3 is a schematic diagram of the bipolar "H" write driver of the present invention.
Illustrative embodiments and exemplary applications will now be described with reference to the accompanying drawings to disclose the advantageous teachings of the present invention.
FIG. 1 is a schematic diagram of a bipolar write driver constructed in accordance with conventional teachings. The write driver 10' includes first and second write resistors 12' and 14', respectively, each of which is connected on one end to a source of supply V.sub.CC. The second ends of the first and second resistors are connected to the first and second ends of a tape write head 16' (shown as a coil) respectively. First and second driver circuits 18' and 20' are connected to the first and second ends of the write head 16'. The first driver circuit 18' includes a pre-driver 22' and a first NPN transistor 24'. Similarly, the second driver 20' includes a second pre-driver 26' and a second NPN transistor 28'.
To write on the tape (not shown), the first driver is triggered by a pulse applied to the input terminal "IN1" thereof. The pre-driver is a buffer which turns on the transistor 24'. This draws current through the first write resistor 12' and the write head 16' and the second write resistor 14'. To write, current is caused to flow in the opposite direction through the write head 16' by the second driver 20'.