BM-141GE / BB-141GE
40
The below calculating formula shows the relationship between the PE value used by the
camera for the different readout modes and the value entered in register 0xA018.
Due to round down figure, some errors may occur.
The relation between PE value and Time Abs
Normal readout PE= 2 + INT (Exposure time -63) µs / (1830/58000000)
V Binning readout PE= 2 + INT (Exposure time -75) µs / (2193/58000000)
INT means round down.
The following table shows minimum value and maximum value for each readout mode.
Minimum value
Maximum Value
Normal Scan
63 .103 μs
33192 μs
2/3 Partial Scan
63 .103 μs
24358 μs
1/2 Partial Scan
63 .103 μs
19973 μs
1/4 Partial Scan
63 .103 μs
13410 μs
1/8 Partial Scan
63 .103 μs
10128 μs
V-Binning Scan
75.62 μs
19926 μs
GPIO in combination with Pulse Width trigger
More precise exposure time can be obtained by using GPIO in combination with Pulse Width
mode. The clock generator and counter can be programmed in very fine increments.
As for the setting example, refer to chapter 6.5.1.
9.2. Full Auto Exposure function
The Full Auto Exposure function combines three automatic functions; Lens Auto Iris, Auto
Gain Control(AGC) and Auto Shutter. When dealing with widely varying lighting conditions,
these automatic functions can be made to work in a coordinated fashion to control exposure
for a constant video level output. This function makes the BM-141GE and BB-141GE well-
suited for Intelligent Traffic Systems (ITS) and high-end security or surveillance applications.
Full Auto Exposure requires the use of a video controlled auto-iris lens system. The lens
should be connected while the power to the camera is OFF.
This Full Auto Exposure function operates as described below.
AGC operation
27
ｄ
B
～
0
ｄ
B
Gain is fixed at 0 dB
Dark
Light changes
Bright
Shutter OFF
（
1/25s)
Auto shutter operation
1/25s to 1/250s
Shutter fixed (1/250s)
Iris diaphragm fixed (Open)
Auto iris operation
