Introduction

The CMOS sensor module (IMX296) incorporates the following features:

resolution to 1448 x 1088 gray scale or RGB Bayer mosaic
supports window AOI mode with faster readout
global shutter
programmable readout timing with free capture windows and partial scan
many trigger modes (free-running, hardware-triggered)

Details of operation

The sensor uses a global shutter, i.e. light exposure takes place on all pixels in parallel, although subsequent readout is sequential.

Free running mode

In free running mode, the sensor reaches its maximum frame rate. This is done by overlapping erase, exposure and readout phase. The sensor timing in free running mode is fixed, so there is no control when to start an acquisition. This mode is used with trigger mode Continuous.

To calculate the maximum frames per second (FPS_max) in free running mode you will need following formula:

Name	Value
InternalLineLength	3072
VerticalBlankLines	32
SensorInClock	75 MHz

                 InternalLineLength            ImageHeight + VerticalBlankLines 
FrameTime =  ------------------------------ * ----------------------------------
                   SensorInClock                          1000

If exposure time is lower than frame time:

                 1
FPS_max =  ------------
            FrameTime

If exposure time is greater than frame time:

                 1
FPS_max =  --------------
            ExposureTime

Snapshot mode

In snapshot mode, the image acquisition process consists off several sequential phases:

Trigger

Snapshot mode starts with a trigger. This can be either a hardware or a software signal.

The following trigger modes are available:

Mode	Description
Continuous	Free running, no external trigger signal needed.
OnFallingEdge	Each falling edge of trigger signal acquires one image.
OnRisingEdge	Each rising edge of trigger signal acquires one image.
OnHighExpose	Each rising edge of trigger signal acquires one image, exposure time corresponds to pulse width.

See also: Using external trigger with CMOS sensors

Erase, exposure and readout

All pixels are light sensitive at the same period of time. The whole pixel core is reset simultaneously and after the exposure time all pixel values are sampled together on the storage node inside each pixel. The pixel core is read out line-by-line after exposure.

Note: Exposure and read out cycle is carry-out in serial; that causes that no exposure is possible during read out.

The step width for the exposure time is 1 us.

Image data is then shifted out line-by-line and transferred to memory.

To calculate the maximum frames per second (FPS_max) in snapshot mode you will need following formula:

FPS_max =                  1
           -----------------------------------
                 FrameTime + ExposureTime

Frame rate calculator

Note: The calculator returns the max. frame rate supported by the sensor. Please keep in mind that it will depend on the interface and the used image format if this frame rate can be transferred.

Note: The exposure time step width is limited to the sensor's row time of 40.96 us and therefore
- auto exposure with very low exposure times will perform with relatively large increments and
- exposure mode = TriggerWidth (if available) will perform with a jitter corresponding to the row time.

Sensor Data

Device Structure

CMOS image sensor (Type 1/2.8)
Number of effective pixels: 1448 (H) x 1088 (V)
Unit cell size: 3.45um (H) x 3.45um (V)

Characteristics

Color version

Gray scale version

Device Feature And Property List

Frame rate calculator
Mode:	Overlapping exposure and readout
Product:	BVS CA-UB1
Output image bit depth:	8 bit 10 bit 12 bit
Pixel clock:	75 MHz
Image width:	pixels
Image height:	pixels
Exposure time:	us
Device throughput:	Device Sensor Throughput Device Link Throughput
Link speed:	USB 2.0
Frame rate (max):	1/s
	ExposureTime > FrameTime → FPS = 1 / ExposureTime