Sharp VL-C780S Serviceanleitung Seite 207

. Digital integration circuit
The low frequency data (0.1 MHz ~ 1 MHz) and high freqauency data (1 MHz ~ 2 MHz) are sent from the
gate array to the A/F microcomputer by means of serial transfer (see Fig. 7-2 (c)).
Digital integration is performed in the area shown in Fig. 7-2 (d), where the two patterns are automatically
changed and monitored according to the condition of the object and monitored.
1c902 1€901
GATE ARRAY A/F MICROCOMPUTER
— ~
nD
i ~~
es)
PATTERN 1 PATTERN 2
{at ordinary condition) (at low contrast)
Figure 7-2 (d). Focus Area.
. Focus motor drive circuit
Ad F-microcomputertC904-drives the-fecus-meter{(DCmotor)-by-using-the-9-kinds- of-drive-pulses-(Fig--7-2-(f})
having different duty ratios according to the condition of imaging. The drive pulses are synchronized with
VD3 (3-dividing of VD, A/F gate array |C902 (51) output} and outputted from A/F microcomputer IC901 (14)
(NEAR end direction) and (15) (INF end direction).
Receiving the drive pulses from the A/F microcomputer, focus motor driver IC904 drives the focus motor.
Motor drive voltage section is made by adjusting the voltage applied to pin (5) by means of the volume (pin
(9) is the constant voltage circuit output of +5V). D903 and D904 are the damper diodes at starting of the
focus motor. Pin (6) is the terminal for reset of the A/F microcomputer.
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18, hg!
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