International Business Machines Corporation

Overhead Door Corporation of Texas

John E Bateson

Dale R Duvall

Barry R Cavill

David Paul Hewitt

Ludwig R Siegl

Lew V Hewitt

Delbert C Thomas, Jr

Albert A Nawy

Gregory N Baker

Samuel E Bigbie

Earl T Brown

Hortensia E Delgado

Obstruction detector apparatus operatively coupled to an automatic electric door operator compares the time span of transmission and receipt of reflected echoes of ultrasonic energy within a door passageway obstruction zone with predetermined time spans in order to prevent door closure under conditions indicating passageway obstruction or system malfunction. Signal generators provide timing signals respectively representative of the anticipated time span of reflected echoes from locations in front of, and beyond, the door jamb opposite the ultrasonic transmitter and receiver transducers for comparison by a relay controller with the time of generation of a signal representing a reflected echo at the transducer receiver, the relay controller appropriately actuating a door operator relay in response to such comparison. Various network portions provide pulse generation to the transmitter, an initial blanking period during which reflected echoes are disregarded, and programmed gain control for electronically shaping an obstruction detection zone to a proximate area of specific interest.

Acoustic obstruction detector and method

In a control system for a bidirectional printer capable of printing at different speeds on different lines and in which the actual velocity of the print carriage is compared with a desired velocity profile to generate an error count, the error count is measured and averaged out for each direction and speed of carriage movement to compensate for the effect of changes in the printer system dynamics such as aging, wear, debris buildup, etc.

Printer control system with error count averaging

A microprocessor controlled printer includes a forms feed assembly, a dot matrix print assembly, a ribbon drive assembly and a number of emitter assemblies associated with the foregoing to provide positional information during operation of the printer which prints on a line-by-line basis. During the printing of characters, such as Kanji characters, extremely accurate control of dot placement is required. In order to achieve a balance between the operating cycle times of the microprocessor and the forms feed assembly, the microprocessor analyzes emitter pulses in two stages. One stage involves use of relatively low frequency emitter pulses for start-up, normal speed, and high speed operations. Another stage involves use of an additional emitter track that produces high frequency pulses utilized by the microprocessor during stopping conditions to achieve greater precision in final positioning of the forms.

Microprocessor controlled positioning system

Growing community of inventors

Carrollton, TX, United States of America

John E Bateson