1M28, 1M75, and 1M150 User’s Manual
PRELIMINARY
31
DALSA
03-32-00525-04
Figure 21: Free Running Mode, Constant Image Data Rate
Frame Timer
Integration
Readout
Integration
Reset
Figure 22: Free Running Mode, Variable Image Data Rate
Integration
Readout
Integration
Readout
Global Shutter Timing
With a global shutter, the sensor starts with a global reset of all pixels. Then during the integration
time, photo-generated electrons are collected in the pixels. After the exposure time, the collected
electrons are transferred to a storage node, and sequential readout of the sensor matrix begins. As a
result, all pixels are exposed to light for the same amount of time, resulting in crisp images that do
not suffer from the time displacement artefacts characteristic of rolling shutter CMOS cameras.
Figure 23: Global Shutter Timing
Reset
Data
Global shutter
Reset
Integration
Frame Readout
Freerunning Mode
The freerunning mode is the factory set timing mode at power up and captures images without the
need for an external control signal. The sensor data is read out after the set integration time. After
the sensor is finished reading out, the sensor resets and the sequence begins again. The data is
output on the rising edge of the pixel clock.
The signals FRAME_VALID (FVAL) and LINE_VALID (LVAL) mask valid image information.
The number of clock pixels after exposure
CPRE
is defined by the calculation of the frame time
(see section 1.12 Calculating Frame Rate).