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1-4. Circuit Description
1-4-1. PR-312 Board
Input signals Y, Pb, and Pr are passed through a buffer and pre-fi lter, converted from analog to digital in
74M 10 bits, and then input to FPGA. In FPGA, a video level is adjusted to the prescribed level using a
multiplier. After that, the input signal is passed through a clamping circuit for the next process. Then, the
resultant signal is sent to a circuit that controls a color-difference component when gray scales are added
on both sides of a screen. (Black & White mode and color peaking) The signal is then controlled in
brightness and converted into RGB using a matrix circuit. Lastly, an RGB 8-bit 37M output signal is sent
to the VPR-103 board through MAG control (screen expansion). Each mode switching from the SW-1436
and SW-1437 boards is controlled by FPGA on the PR-312 board, and an internal digital signal is con-
trolled by the level signal, from the VR-328 board, converted from analog to digital on the PR-312 board
(ex. bright level). The PR-312 board mounts S1, S2, and S3. S1 is used for the same external mode
switching (opened to users) as for HDVF-C30W. S2 and S3 are used for factory adjustment.
1-4-2. VPR-103 Board
The RGB 8-bit 37M signal from the PR-312 board is color-converted, gamma-converted, panel-corrected
by IC101, and output to an LCD module. Moreover, it has a function that saves conversion and correction
functions and outputs them directly to a panel. The RGB 8-bit 37M signal from the PR-312 board is once
read into CPLD. The CPLD functions as a signal selector and controls whether to send the signal to
IC101 (color conversion, gamma conversion, and panel correction) in the next stage or send them directly
to the LCD module. When the RGB 8-bit 37M signal is sent to IC101, higher-precision reproducibility
can be obtained by performing each conversion or correction for a panel in IC101. After that, the signal is
passed through CPLD again and sent to the LCD module. The VPR-103 board also mounts a backlight
driver that changes the voltage of LCD backlight and adjusts the contrast.
1-4-3. RE-257 Board
The RE-257 board consists of fi ve switching regulators of analog and digital signal processing voltages (1.2 V,
1.8 V, 2.5 V, 3.2 V, and -7 V). The switching regulators have a short-circuit detection protection function,
respectively. They convert the UNREG voltages from a camera into the voltages above and detect the UNREG
voltages. The switching regulators also have a protection function during generation of low and high voltages.
1-4-4. VR-328 Board
There are two external and internal volume controls for control of brightness, contrast, and peaking. The
VR-328 board mounts a function that switches the volume controls using a [SEL] (SEL1/SEL2 selector)
switch and a tally lamp drive circuit. It also mounts a selector switch for reversing the right and left of a
display screen. The selector switch operates in linkage with the installation of a VF tube.
1-4-5. SW-1436 Board
The SW-1436 board mounts a selector switch of tally, zebra, marker, B&W, and MAG functions. The
obtained information is sent to the PR-312 board.
1-2 (E)
HDVF-C30WR
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