Browse Prior Art Database

Constant Thermal Dissipation Area Array CCD Sensor

IP.com Disclosure Number: IPCOM000108883D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Dean, AJ: AUTHOR [+2]

Abstract

A large field size, multiple output tap CCD sensor has been developed for a scanning confocal imaging system used for high-speed inspection of thin film packaging. The confocal imaging technique is sensitive to very small dimensional changes in the CCD sensor array which cause unwanted transient variations in the amount of collected light. The dimensional changes are caused by changes in the power dissipated by output amplifiers at each output tap.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 80% of the total text.

Constant Thermal Dissipation Area Array CCD Sensor

      A large field size, multiple output tap CCD sensor has been
developed for a scanning confocal imaging system used for high-speed
inspection of thin film packaging.  The confocal imaging technique is
sensitive to very small dimensional changes in the CCD sensor array
which cause unwanted transient variations in the amount of collected
light.  The dimensional changes are caused by changes in the power
dissipated by output amplifiers at each output tap.

      The output amplifiers are located along opposite edges of the
photosite array in close proximity to the photosites. The transient
thermal dissipation from the output amplifiers is sufficient to
produce a transient temperature gradient across the CCD sensor.  The
thermal gradient causes an unwanted shift in the relative location of
photosites. Since the confocal technique requires exact alignment
between respective illumination and detector pinholes, the transient
thermal distortion of the sensor causes degradation of system
performance.

      This invention eliminates the transient power dissipation by
adding circuitry to the CCD sensor.  This is achieved by adding a
compensating resistor which dissipates heat inversely with the CDD
sensor dissipation.  If the output amplifier is on, the resistor is
off.  This concept can be implemented by designing resistors into the
CCD sensor circuitry in close proximity to the output amplifiers.
The resistors...