SECTION XI: DIGITAL CONVERGENCE CIRCUIT
1. OUTLINE
The digital convergence circuit develops outputs to correct screen distortion and perform color matching. The digital convergence circuit used is of an all digital type and allows good adjustments in comprise with a conventional analog type circuit.
Followings are features of the digital convergence circuit.
1)No adjustment controls (volumes)
2)Registration accuracy increased.
3)Space saved
4)Adjustment by a remote control
The data adjusted are classed into 4 screens for each screen mode. These data are stored on E2PROMs inside the unit. The memory size used in this case is 4 Kbits per one screen.
Each screen adjustment is carried out by calling the adjust- ment screen with the remote control unit supplied and the adjustment is carried out according to the dimensions speci- fied for each screen. The control of the unit is carried out in the I2C format.
2. CIRCUIT DESCRIPTION
2-1. Configuration
Fig. 11-1 shows a block diagram. The digital convergence unit consists of Q701 T7K64 which plays a major role, Q707 PLL circuit which locks a sync entered, Q713 E2PROM to store the data, and Q703-5 D/A converter which develops a correction wave form.
The output signal from the Q703 – 705 D/A converter is amplified and wave form shaped by Q715, Q717 and Q719, and comes out from the unit.
The clock signal for the PLL is adjusted by L719 to a refer- ence frequency of 32 ± 0.1MHz under no input status.
A test pattern generator is also built inside Q701 and devel- ops R, G, B signals and a Ys switching signal.
(1)With the power turned on, the unit is reset and enters an operation standby status. And a sync signal of the unit enters external Q707 and Q701. The signal en- tered Q707 is counted down by a counter inside the Q701 and this is used as the reference clock. Q701 works in synchronization with the reference clock sig- nal and the sync signal.
(2)A command is sent from the microcomputer in the unit and Q701 is set up to load the data in Q713 to the in- ternal RAM. (8 (horizontal) x 7 (vertical) x 3 (color))
(3)Q701 transfers a serial data specified to Q703 – 705 according to the RAM data. In this case, interpolation for the RAM data is automatically carried out by a built
(4)The serial data sent from Q701 are
(5)The signals sent from Q703 – 705 are amplified Q715, Q717, Q719, respectively, and then filtered in the next stage to smooth and shape the wave form. Thus pro- cessed signals are used as H and V correction wave forms for R, G, and B signals.
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