Browse Prior Art Database

Validity Checking of Grey-Scale Image Data on an Electrochromic Display

IP.com Disclosure Number: IPCOM000041414D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Pinnell, MC: AUTHOR

Abstract

An electrochromic display device attached to a processor, such as the IBM Personal Computer, can be used to display images with up to 64 gradations of grey scale. The display technology is such that the intensity of coloring of a picture element is proportional to the length of time for which an electric charge is applied to the picture element cell in the electrochromic array. When displaying a grey scale image, it is convenient to build up the image by a series of write operations to the array, doubling (or halving) the write time between one operation and the next. For example, if a pattern of '0' and '1' bits is used to gate a charge on to a pel row of an electrochromic array for 0.275 msec then another pattern is used for 0.55 msec, then another for 1.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 1 of 2

Validity Checking of Grey-Scale Image Data on an Electrochromic Display

An electrochromic display device attached to a processor, such as the IBM Personal Computer, can be used to display images with up to 64 gradations of grey scale. The display technology is such that the intensity of coloring of a picture element is proportional to the length of time for which an electric charge is applied to the picture element cell in the electrochromic array. When displaying a grey scale image, it is convenient to build up the image by a series of write operations to the array, doubling (or halving) the write time between one operation and the next. For example, if a pattern of '0' and '1' bits is used to gate a charge on to a pel row of an electrochromic array for 0.275 msec then another pattern is used for 0.55 msec, then another for 1.1 msecs, the result will be a pel row of an image containing possibly eight gradations of grey scale. A program running in the IBM Personal Computer can in principle cause a grey scale image to be displayed by transferring to the electrochromic display adapter a series of records each containing a pel row number specifying the pel row which is to be written in the array; an intensity code specifying the time duration of the write operation; and a pattern of '0' and '1' bits, indicating by the presence of the '1' bits in the pattern the picture elements which are to be written in the specified pel row. A problem associated with electrochromic displays is that writing to a cell for more than a few milliseconds without an intervening erase can damage the array. To avoid this damage, it is necessary for the display adapter to validate any picture data before using it. In its most rigorous form, validation would involve keeping a record of the total duration for which each picture element cell had been written. That would be equivalent to retaining in the adapter a complete copy of the coded grey scale data while an image is being painted. For an image array of 320 x 300 picture elements with up to 64 gradations of grey scale, this would require the provision of 72,000 bytes of random-access memory in the adapter. A sufficient condition for safe writing of images to any array is that successive records transferred to the adapter shall, consistently throughout the painting of an image, exhibit either an increasing or a decreasing value of pel row number and intensity code when the...