Outlined Software Descriptions - NEC MultiSync LCD2080UX -BKA Service Manual

1. Outlined Software Descriptions

The LCD2080UX is a 20.1-inch LCD monitor equipped with two systems of input connectors.
INPUT1 is the DVI-I connector that can pick up an input of either the digital signal (TMDS) or the analog
signal. INPUT2 is provided with the DVI-D and VGA connectors either of which can be used for the input
entry.
The analog input signal is selected in the RGB 2ch analog signal changeover circuit, incorporated in the AD
converter (ICA01). The AD converter is used to convert the RGB signals into the digital signals, each
consisting of 8 bits. The sampling frequency for AD conversion is generated through the multiplication of the
sync signal. This signal frequency is transferred to the signal processor IC (IC4A1) together with the
converted data.
In regard to the DVI digital signal input, on the one hand, the TMDS signal is decoded at the TMDS receiver
(ICK01 or K02) and then transferred to IC4A1. For the two TMDS receiver outputs, each has a capacity of
wiring for 8 bits × 3 (RGB) × 2 (pixel/ clock) = 48 bits. These circuits are connected in the wired OR mode in
order to reduce the number of circuit parts.
The signal processor IC (IC4A1) has the functions of sync signal telemetry, delay compensation, and color
adjustment. The data after AD conversion or those decoded at the TMDS circuit are entered in the scalar
LSI (IC401) via IC4A1. The scalar LSI tentatively stores the image data in its internal SDRAM for the
purpose of extended conversion processing. The OSM images are also generated here. The control
program of extended conversion and the OSM image data are stored in the flash memory of IC402. The
rate of extended conversion and the OSM image data are controlled by the MPU (IC804) through the UART
communication line (TXD, RXD).
The data processed in IC401 are sent to the LVDS transmitter. The LVDS signal is decoded again in the
LCD panel control PWB, and the pictures are displayed at the panel.
The MPU is in charge of input signal discrimination, AD converter control, OSM control, key scan, signal
reset detection, power sequence control, inverter control, signal processor IC control, hours running control,
and so on. The IC804 program is stored in the internal ROM or the flash memory, and the user adjustment
2
data are stored in the EEPROM (IC803) through the I C bus.
7-3