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3.1.3 (a)
Field Mode
In Field Mode, two horizontal rows are scanned together, changing the pair at each interlace scan. The
sensitivity of the CCD is doubled for one field of integration, therefore it can obtain the same sensitivity
as in Frame Mode in half the period of time. This is an advantage when the shutter is used often.
Because of the alternating two row scanning, Moire is almost unnoticeable. While the vertical resolution
is not as good as in Frame Mode, it is sufficient to view the full vertical resolution of the TV format.
Note:
Only odd fields are output in this mode. Field Mode cannot provide full frame resolution
with strobe lighting applications.
3.1.3 (b)
Frame Mode
In Frame Mode, each horizontal row is scanned as interlace scanning. The integration of each pixel is
one frame period. Vertical pixel resolution is good, and exact location is obtained. A disadvantage as
compared with Field Mode is the tendency to show vertical Moire. For strobe lighting, Frame Mode
must be used to achieve full frame resolution.
3.1.4 Integration
The CCD imager of the TM-200/TM-300 can be exposed longer than normal TV timing (16.7 msec.).
This feature provides high sensitivity for dark environment applications.
Pin #11 of the 12-pin connector is the control pin for integration. It accepts standard TTL inputs. High is
considered 5 Volts and Low is considered 0 Volts. You may enable (i.e., not actually start integrating an
image) integration by applying a high signal to pin #11. Then, when a low voltage is applied to the same
pin #11, the integration process begins. Integration blocks the transfer gate of the image data out of the
CCD array. Think of a transfer gate(sg) as a floodgate that lets water out of a lake (CCD array). Upon
returning the signal back to high which is required to end the process, the image is output.
Set the camera in frame mode to output two fields of information. In this mode, the output fields appear
to have different exposures, so this may cause problems in some applications. Set to field mode to
output one frame with only one frame of resolution, one field is doubled to obtain one frame (this is not
a true full frame of information).
3.1.5 External Sync
The TM-200/TM-300 can accept external sync from an external sync generator or frame grabber. Input
specifications:
Internal/External auto switch
fH+15.734 KHz ±5%, fV +59.95 Hz ±5%
Note:
The TM-300 has a one (1) horizontal line delay between the input VD signal and the
output video. If external vertical drive (VD) is applied to the camera, it may cause the
video output to be delayed 1 HD (1 H = ~64.0 µs). If the imaging system is capable of
automatically detecting the start of video (within a few HD), then no problem will exist.
Otherwise, re-configure the video capturing sequence to delay video acquisition of 1H.
TM-200 / TM-300 Miniature CCD Camera
OPERATION
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