Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!cs.utexas.edu!csc.ti.com!tilde.csc.ti.com!mksol!strohm
From: strohm@mksol.dseg.ti.com (john r strohm)
Subject: Re: CCD shuttering
Message-ID: <1994Feb14.184750.29078@mksol.dseg.ti.com>
Keywords: CCD
Organization: Texas Instruments, Inc
References: <CL2s1E.KLz@ucdavis.edu>
Date: Mon, 14 Feb 1994 18:47:50 GMT
Lines: 24

In article <CL2s1E.KLz@ucdavis.edu> nelsonk@bunsen.cs.ucdavis.edu (Karl Nelson) writes:
>Hello.  I am working on constructing a low resolution CCD camera for a
>small robot.  I plan to use a TC211 chip to take the pictures.
>However, the chip lacks a buffer area.  Therefore, I must either
>shutter the CCD or pull the image out faster.  By my calcs it shows
>that to pull out the image it would tkae at least 3ms to pull out the
>image that maximum operating speed given by TI (10Mhz).  Given a
>sample time of 15ms that gives me a twenty percent error.  Does anyone
>know if the CCD can be operated higher that the recommended max?  If
>not, are there any other recommendations on how the shutter the CCD
>aside from liquid crystal?  Please post or mail any experiences or
>possible solutions to my delemma.  My email address is
>kenelson@ucdavis.edu.

The canonical cheap shutter technique is a really nasty neutral density
filter and a really hot xenon strobe.  This will make you unpopular if
the robot has to coexist with humans, but is quite common in computer
vision systems.

This of course assumes that you can tolerate a low frame rate, since the
frame rate would be limited by the strobe rate.

You could do a low-budget variation of this with a high-intensity bulb
and a motorized slotted wheel.
