Browse Prior Art Database

Intensity Control Circuit for Segmented Display Elements

IP.com Disclosure Number: IPCOM000052960D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Ossowski, R: AUTHOR

Abstract

This article describes a simple logic circuit for controlling the display intensity of optical display elements such as LED (light-emitting diode) matrices or multi-segment LED characters. An N-bit shift register can be loaded under program control to establish a variable width pulse which, when gated to the display element driver gates, can be used to vary the intensity.

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Intensity Control Circuit for Segmented Display Elements

This article describes a simple logic circuit for controlling the display intensity of optical display elements such as LED (light-emitting diode) matrices or multi- segment LED characters. An N-bit shift register can be loaded under program control to establish a variable width pulse which, when gated to the display element driver gates, can be used to vary the intensity.

Referring to the drawing, an N-bit shift register 10 can be loaded serially or in parallel under the control of a program or at the request of an operator. A load register latch 12 is used to initiate loading of the shift register 10. Assuming that a binary 1 indicates a predetermined pulse width, the shift register 10 can be loaded with anything from a single one (minimum intensity) to N ones (maximum intensity).

The contents of shift register 10 are shifted at a rate determined by an oscillator 14. The output of shift register 10 is applied both to an output gate 16 and to an input gate 18. The second input to each of the AND gates 16 and 18 is provided by an activate latch 20. When the output of latch 20 is at an enabling level, the contents of the shift register 10 are looped back to the input of the register through the AND gate 18 and are applied to display element driver gates through the output AND gate 16.

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