PIXELVISION SPECTRAVIDEO, User Manual, Page: 29 / 51

SpectraVideo Camera User’s Manual Shutter and Cooler Control Board
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8. S
HUTTER AND
C
OOLING
C
ONTROL
B
OARD
The shutter and cooler control board provides the drive circuitry to control the
shutter as well as temperature control for the thermoelectric cooler (TEC) and
CCD. The shutter supply circuit operates from the +15V power supply to make
+70V for the shutter. During exposures, closing a switch between the supply and
the shutter opens the shutter. Immediately after exposure, the shutter supply
recharges. The Camera External Sync output is low during the time the shutter is
open and +5V otherwise.
PixelView uses two constants called TempGain and TempOffset. These values
are used to convert a temperature to a binary value to send after the ‘x’ command:
) TempOffset Kelvin _ in _ ccdtemp (
100
TempGain
256 x
− ∗ ∗ =
The TempGain and TempOffset constants are CCD package and camera specific,
they are calibrated for each camera. A temperature sensor inside the TEC package
converts temperature to current. The current passes through a resistor and the
voltage on the resistor (representing CCD temperature) is displayed by a
Voltmeter LCD display. Temperature can be set in PixelView in Control,
Camera Setup… (Ctrl-C), by using the CCD temperature slider in the CCD tab
within the “Camera Setup” dialog box.
Figure 9 SpectraVideo Shutter and Cooler Control Board Layout