Browse Prior Art Database

Bipolar Method for FE PC Storage Device Readout

IP.com Disclosure Number: IPCOM000074015D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Chapman, DW: AUTHOR

Abstract

In one method of readout from ferroelectric-photoconductor devices, the readout signal is generated by applying a single polarity of readout drive pulse simultaneously with light to cause switching of the addressed bit position in a single direction. The amount of charge switched when a "1" is stored is larger than the amount of charge switched when a "0" is stored, and this is the basis for deciding whether a 1 or a 0 is read out. This is illustrated in the figures which shows the 1 and 0 storage states together with their readout signals. A shows ferroelectric hysteresis and storage states. B shows readouts for 1 and 0. The readout signals are the voltage levels (= Q/C) observed on an integrator in series with the device.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 2

Bipolar Method for FE PC Storage Device Readout

In one method of readout from ferroelectric-photoconductor devices, the readout signal is generated by applying a single polarity of readout drive pulse simultaneously with light to cause switching of the addressed bit position in a single direction. The amount of charge switched when a "1" is stored is larger than the amount of charge switched when a "0" is stored, and this is the basis for deciding whether a 1 or a 0 is read out. This is illustrated in the figures which shows the 1 and 0 storage states together with their readout signals. A shows ferroelectric hysteresis and storage states. B shows readouts for 1 and 0. The readout signals are the voltage levels (= Q/C) observed on an integrator in series with the device.

The 1 and 0 readouts are in the same polarity, and discrimination between them must be on the basis of their difference in amplitude. This can result in serious problems, in that if the ferroelectric's hysteresis loop (or the FE/PC device's photoconductor properties, or the diameter of the addressing light beam, or the light-beam intensity, etc.) varies from spot to spot on the FE/PC chip, then the amplitude of a 0 from one location can be larger than the amplitude of a 1 from another location even though all the 1's are larger than all the 0's for their own respective locations. This problem makes it very difficult to set a clipping level for signal discrimination.

This problem is solved by the...