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Cathode Ray Deflection System Using Field Effect Transistors

IP.com Disclosure Number: IPCOM000077543D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Gianopulos, W: AUTHOR

Abstract

A field-effect transistor (FET) shift register is used to generate deflection voltages for cathode-ray tubes, so that by changing the data in the shift register the cathode-ray beam can be made to scan the face of the tube.

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Cathode Ray Deflection System Using Field Effect Transistors

A field-effect transistor (FET) shift register is used to generate deflection voltages for cathode-ray tubes, so that by changing the data in the shift register the cathode-ray beam can be made to scan the face of the tube.

Referring to Fig. 1, shift register 10 is a static FET shift register where each of the stages 1 through n contains cross-connected FET flip-flop. As shown in Fig. 2, in each of the stages, load FET Q3 couples the drain of cross-connected FET Q2 to the emitter of transistor Q11 in the push-pull driver 12 (Fig. 1), while load FET Q5 couples the drain of cross-connected FET Q4 to the emitter of transistor Q12. The current flowing through transistors Q11 and Q12 will, therefore, depend on what state the cross-connected cell is in each of the stages of shift register 10.

Assuming that a "0" is stored in each of the stages of shift register 10, Q4 would be conducting and Q2 would be nonconducting in each of the stages of shift register 10, Q11 would be conducting very lightly while Q12 would be conducting very heavily.

Assuming that a "1" is stored in each of the stages of shift register 10, Q2 would be conducting and Q4 would be nonconducting, Q11 would be conducting very heavily and Q12 would be conducting very lightly.

Thus, the currents at the collectors of Q11 and Q12 are in phase opposition and can be changed by changing the data in shift register 10. These currents are amplified by amplifier stages consisting of transistors Q13 and Q14 and transistors Q15 and Q16, respectively, and passed through the push-pull yoke 14a and 14b of a cathode-ray tube.

Therefore, by changing the data stored in the shift register the current through the push-pull yoke can be altered, to deflect the beam across the face of the tube.

Assume that initially each of the stages of shift register 10 contains a 0, so that in each stage Q4 is conducting and Q2 is nonconducting. Then a 1 signal is applied to the first stage of the shift register so that the drain of Q1, is raised. At the same time the phase signal phi is raised. This causes Q2 to conduct, dropping the voltage at the gate of Q4 and turning it off. With Q2 conducting, the current increases through Q3 so that current at the emitter of Q11 increases. At the same time, the current in Q5 of the first s...