Overview For Cameras With Cmos Sensor - Basler acA2040-55 User Manual

AW00123409000
4.2 Overview for Cameras with CMOS
Sensor
Cameras with CMOS sensor are listed in Section 1.3.2 on
The cameras provide functionalities such as an electronic rolling shutter or a global shutter (see
Section 6.6 on page 142), and electronic exposure time control.
Exposure start and exposure time can be controlled by parameters transmitted to the camera via
the Basler pylon API and the USB 3.0 interface. There are also parameters available to set the
camera for single frame acquisition or continuous frame acquisition.
Exposure start can also be controlled via an externally generated "frame start trigger" signal applied
to a camera input line (hardware frame start trigger; HWFSTrig). The HWFSTrig signal facilitates
periodic or non-periodic frame acquisition start. Exposure modes are available that allow the length
of exposure time to be set for a pre-programmed period of time or, with the exception of some
camera models, to be directly controlled by the HWFSTrig signal.
During exposure, electrical charges accumulate in the sensor's pixels. After exposure was ended,
the accumulated charges are read out of the sensor. At readout, the charges are transported from
the row's light-sensitive elements (pixels) to the analog processing controls (see Figure 36 on
page 66). As the charges move through the analog controls, they are converted to voltages
proportional to the size of each charge. Each voltage is then amplified by a Variable Gain Control
(VGC). Next the voltages are digitized by an Analog-to-Digital converter (ADC). After the voltages
have been amplified and digitized, they are passed through the sensor's digital controls for
additional signal processing. The digitized pixel data leaves the sensor, passes through an FPGA,
and moves into a buffer.
The pixel data leaves the buffer and passes back through the FPGA to a controller where it is
assembled into data packets. The packets are then transmitted by bulk transfer via a USB 3
compliant cable to a USB 3 host adapter of the host computer. The controller also handles
transmission and receipt of control data such as changes to the camera's parameters.
Basler ace USB 3.0
Camera Functional Description
page 8.
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