Browse Prior Art Database

Controlled Persistence Method

IP.com Disclosure Number: IPCOM000078728D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Kozol, ET: AUTHOR [+2]

Abstract

This method utilizes a variable-pulse technique to attain controlled persistence of the image of a deformographic storage-display tube (DSDT) 1. Such a tube type is described in U. S. Patent 3,676,588.

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Controlled Persistence Method

This method utilizes a variable-pulse technique to attain controlled persistence of the image of a deformographic storage-display tube (DSDT) 1. Such a tube type is described in U. S. Patent 3,676,588.

Controlled persistance is normally attained by varying the DC level or amount of flood current per unit time, to neutralize the stored writing charges. The amount of flood current is varied by bias control at the expense of target coverage, leading to incomplete and nonuniform erasure.

The present method drives flood gun FG at a fixed bias level at control electrode G1. It controls the amount of flood current by an adjustable pulse time period of fixed-pulse width, as determined by the signal at terminal J. By varying the pulse time period, the average flood current can be controlled during the selected erase period.

The figure is a schematic representation of the control scheme. The flood gun FG is referenced 8.5 kv above ground or 1.5 kv below the potential of DSDT target substrate 2. This level is between the first and second crossover points of the secondary emission characteristic of the target substrate. Writing is initiated by 10 kV electrons from write gun WG. As a result, negative charges are formed on the target substrate 2. The 1.5 kv erase or flood electrons neutralize the negative charges to complete the write and erase cycle.

T1 is a one used 1:1 pulse transformer high potted ior 15 kV. Point QA is at +135V with respect t...