Texas Instruments Corporation

W S Henrion

Yogendra C Pandya

Raymond K Erickson, Jr

Lynn B King

A solid state keyboard comprised of a base module, a plurality of key members each having a plunger member comprised of a uniform mixture of a magnetic material such as barium ferrite and a binder such as nylon, and a respective plurality of improved Hall Effect Generators, provides a significant improvement in performance and cost effectiveness. Actuation of a key member moves its plunger member, which has a preselected magnetic field, relative to an improved Hall Effect Generator, in which offset voltage has been substantially eliminated. This movement exposes the generator to a change in the direction of the magnetic field, thus causing a corresponding change in the output voltage of the generator from a first predetermined voltage to a second predetermined voltage. A unique tripolar magnetic arrangement on the plunger member provides positive switching and better control of switching points.

Solid state keyboard

An input/output controller provides a numer of adjustable timers for timing events such as for polling external devices and includes circuitry which generates interrupt vector signals upon the occurrence of certain events, including the expiration of time set in the adjustable timers and also upon receipt of signals from the external devices. The interrupt signals may be selectively masked when it is not desirable or practical for an interrupt to occur. The controller is an MOS N-channel device on a single chip and is packaged in a 40 pin package and is compatible with a Model TMS 8080 Microprocessor Unit.

Input/output controller having selectable timing and maskable interrupt

A thermal printer has a thermal printhead having coincident current-activated semiconductor mesas arranged to a matrix, the number of mesas being greater than the number of x and y drive lines. The printhead has a decoder formed thereon and a number of coincident current lines equal to the number of mesas. The input to the decoder comes from the x and/or y drive lines and selects coincident current lines to provide desired characters according to coded input signals.

Thermal printer having expanded character set thermal printhead

A latching circuit is used in a thermal printhead matrix. The heater circuit in each mesa or element of the matrix, once energized by input logic signals, is thereafter independent of changes in the input logic signal levels and remains energized until the supply voltage is removed. This permits turning on the individual mesas in a matrix fashion thereby substantially reducing the number of input leads required to control the matrix.

Thermal printhead with memory

An integrated semiconductor circuit has a portion thereof divided into a plurality of air isolated mesas which constitute a heater element array. A heater transistor formed within each mesa is selectively turned on in response to logic signals to heat one mesa of the array. By selectively heating the correct mesas, an area of the mesa array corresponding to a desired character is heated. Thermally sensitive material on which a dynamic display is formed or on which a permanent display is printed is in thermal contact with the material of the heater element array. Also formed within each mesa is its corresponding driver transistor.

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Houston, TX, United States of America

W S Henrion