VASC Seminar Announcement
            =========================

Date: Monday, 11/15/99
Time: 3:00-4:00
Place: Smith Hall 2nd Floor Common Area

Speaker:  Toyami Fujita
          Univ. of Electro-Communications, GSIS, Japan
          http://www.hi.is.uec.ac.jp/~fujita

Title: New Type of Position Sensitive Device for Accurate Sensing

Abstract:

PSD(semiconductor image position sensitive device) is useful for position
sensing in an automation system, robotics, and so on.  In present PSD,
produced photo current flows into the dividing resistance and the bright
spot position is calculated from the output currents of dividing resistance.
When the background lights are existing surround the target image, their
photo current affect to the image position calculation, then the sensing
errors are produced.  In order to reduce this detecting error, light
modulating scheme has been used. However, this scheme could not be applied
when the background lights were produced by the target light itself or
target brightness could not be modulated. In this presentation, a new type
of PSD in which the surrounding photo current produced by background lights
can be subtracted and do not flow into the dividing resistance is presented.
The subtractions are made from individual photosensitive element through the
ideal diode which can prevent the interaction between photo current.  In
addition, for the simplicity in manufacturing, different type of PSD without
the interaction prevention diode is also considered.  The computer
simulations have been performed to investigate the detecting characteristics
and it was confirmed that the proposed method would be useful mean.  In
addition, a new type of PSD which can detect the position of black target
image on light background is proposed by adopting the similar method. Some
useful applications using these new types of PSD are also considered.