- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
52
The saturation signal level differs for each type of CCD image sensor. The SS-HQ1 is mainly designed for CCD
image sensors with the saturation signal level of 600 - 1000 [mV]. To ensure the dynamic-range of 2.5 times the
standard level, the standard CCD output (Y-level) of the SS-HQ1 is 250 - 400 [mV]. The exposure time and the
output level of CCD can be controlled by the shutter pulse of built-in TG of CXD3172AR. When using the
mechanical-iris, some control-circuit is necessary.
8.1.1.2. The Output of CDS/AGC
Fig 8.1-3 an example of DRVOUT
CCD output signal is processed CDS, AGC, black-level clamping, preblanking with CXA2096N. And the output
signal of CXA2096N is DRVOUT. DRVOUT, and A/D reference voltages (VRT, VRB) are connected to the
built-in A/D converter of CXD3172AR. In order to reject the black-level change by noises, an offset level can be
added to DRVOUT. In the black-clamping processing of CXD3172AR, the offset level is subtracted in the
integral mean. So the proper signal level is extracted.
The built-in EVR of CXD3172AR can control AGC of CXA2096N by AGCCONT input. CCD output level is small
and gained-up in AGC processing at low-light-condition. If the lowest AGC value is short, the unevenness (dirty
spots) of CCD saturation can be seen at high-light-condition. AGC minimum value is adjusted so that DRVOUT
signal must be saturated (about 1[Vp-p]) before the CCD output level becomes saturated. During AE on, it is
gained over the AGCMIN value.
For example, if it is set up in AGCMIN =4[dB], in theory, the unevenness of saturation can be prevented toward
the CCD which saturation signal level is 650[mV] and more. In addition, when you decide an AGCMIN value,
please actually see drawing and perform the check of S/N and saturation unevenness.
CCDOUT
PBLK
CLPOB
DRVOUT
OFFSET = Black Level
VRB = Blankng
Signal Level = AGCout