Browse Prior Art Database

Free Hand Drawing Display System

IP.com Disclosure Number: IPCOM000073746D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Granzotti, AN: AUTHOR

Abstract

This display system including a light pen allows an operator to draw or erase an image on a display screen with a free-hand motion by inverting the polarity of the display image so that noninformation raster areas are bright spots and information areas are dark spots on the face of the display screen.

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Free Hand Drawing Display System

This display system including a light pen allows an operator to draw or erase an image on a display screen with a free-hand motion by inverting the polarity of the display image so that noninformation raster areas are bright spots and information areas are dark spots on the face of the display screen.

Data stored in raster assembly memory 50 is transferred to converter 60, which converts the data to serial form for transmission to pencil eraser circuitry 100 in which the light pen write/erase signals are combined with the raster information. Light detected by light pen 110 is transmitted to one input of AND 122. A second input is generated by pencil enable and erase switch 126 which is connected to integrators and latches 128 by lines 127 and 129 corresponding to the write and the erase position of switch 126, respectively. When switch 126 is in either the write or the erase position AND 122 is activated allowing the light detect information to be transmitted to delay network 130. After an appropriate delay to align the light detect information with the proper location in the next frame of the raster, the light detect signal appears at AND 140, where it is combined with horizontal and vertical synchronization signals. The output of 140 represents the position in a raster of a location to be operated on and is connected to AND 150 and OR 152 appears as one input to AND 154, with a second input being the output of AND 150. With switch 126 in the write position, AND 150 is inactive causing AND 154 to be enabled, allowing the output of OR 152 to be transmitted to serial-to-parallel converter 70. The output of converter 70 is buffered by buffer 20, which transmits a parallel signal to converter 30 for video generation...