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CV-A11
6. Functions and Operations
Apart from the standard continuous operation, the CV-A11 features three external asynchronous
trigger modes (edge pre-select, pulse width controlled and start/stop) and a special frame-delay
readout mode. Long integration time mode is also supported.
In addition, the CV-A11 also provides a partial scan readout function.
6.1. Basic functions
Some of the primary camera functions need a general introduction before the operation modes
are described. The list below shows the primary functions from the command list.
SM Shutter Mode Normal shutter, Programmable Exposure
SH Shutter Speed Off to 1/100,000 second
PE Programmable Exposure 1.5 H to 1023.5 H
SC Scanning Format Full frame, 1/2 partial, 1/3, 1/6 partial
TR Trigger Mode Normal, Edge, PWC, frame delay readout
Long time exposure, start-stop, smearless (Edge)
HC HD Accumulation H Synchronous, H Asynchronous.
The shutter SM can be set to normal (SM=0), where the exposure time is selected from 15 fixed
step with the command SH, or programmable exposure (SM=1). Here the command PE allows
1023 step with 1 line period resolution (63.5 µs) in triggered mode. For normal mode, PE can be
up to 523 for full, 275 for 1/2, 195 for 1/3 and 115 for 1/6 partial scan.
The CCD scanning format SC can be selected between full or partial scanning. With partial
scanning, only the vertical central part of the CCD sensor is read out with a higher frame rate.
The partial scan is done by a fast dump read out of the lines in the vertical ccd register down to
the top of the partial image. The partial part of the image is read out with normal speed. The
lines below the partial image are read out and dumped with a high speed.
Imaged scene
Partial scanning.
Aspect ratio correct
648 pixels
1/2 PS, 240 pixels
1/6 PS, 80 pixels
1/3 PS, 160 pixels
Imaged scene
Partial scanning.
Aspect ratio correct
648 pixels
1/2 PS, 240 pixels
1/6 PS, 80 pixels
1/3 PS, 160 pixels
Fig. 8. Partial scanning.
The accumulation mode HC is H synchronous (HC=0). For PWC mode (TR =2) and Frame Delay
readout (TR=3) it can also be set to asynchronous accumulation (HC=1).
In H synchronous mode, the exposure in will start at the first HD pulse after the trigger falling
edge. In H asynchronous mode the exposure will start immediately at the leading edge of the
trigger pulse without waiting for the HD. Fig. 9 and fig. 10 shows the details.
HD
Trigger
Xb
Accum
HD
Trigger
Xb
Accum
Fig. 9. PWC H synchronous accumulation. Fig 10. PWC asynchronous accumulation.
In normal continuous mode (TR=0) shutter speed up to 1/100,000 second can be used. In
triggered shutter modes, the shortest shutter time is limited to ≥1,5 H or 1/10,000. In triggered
shutter modes with full and partial scan, the exposure time is not limited to the frame read out
time. It can be longer.
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