Browse Prior Art Database

Regenerative Photocell using Charge Coupled Device Structure

IP.com Disclosure Number: IPCOM000079555D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Stinson, WF: AUTHOR

Abstract

This device allows the use of charge-coupled device (CCD) technology for fabricating high-speed linear scanners by decreasing their exposure time. The circuit employs a potential well, bootstrapping action to amplify the photogenerated charge flow rate onto a diffusion, or into a potential well. This allows a reduced exposure time for any given light intensity level.

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Regenerative Photocell using Charge Coupled Device Structure

This device allows the use of charge-coupled device (CCD) technology for fabricating high-speed linear scanners by decreasing their exposure time. The circuit employs a potential well, bootstrapping action to amplify the photogenerated charge flow rate onto a diffusion, or into a potential well. This allows a reduced exposure time for any given light intensity level.

Light flux impinging upon a doped silicon substrate generates hole-electron pairs at a rate proportional to the flux density. The increase of minority carrier density causes a net diffusion of electrons in a P-type substrate toward regions of positive potential within the silicon where they are collected, unless they have recombined before reaching the positive potential region. A charged diffusion or a potential well under a biased electrode acts as a collector of photogenerated charge. Monitoring the rate of flow of charge onto the diffusion or into the potential well, provides a method of measuring the intensity of light within a diffusion length from the diffusion or well. The regenerative photocell illustrated in the figure uses a P-type substrate to an overlapped gate charge-coupled devices. Substrate 2 is biased negatively at Vs; N+ diffusion 3 is biased at ground potential; N+ diffusion 5 and gate G4 are biased at a high-positive potential Vp.

In operation, when a positive potential Vg5 which is greater than Vp as applied to polycrystalline silicon gate G5, N+ diffusion 4 and electrode G2 are charged to Vg5 - Vth, thereby creating...