Sanyo VPC-GH2 Service Manual page 5

4. Lens drive block
4-1. Focus drive
The 16-bit serial data signals (LENS_SDI) and (LENS_SCLK
and LENS_EN) which are output from the ASIC (IC101) are
used to drive (FOCUS A +, FOCUS A -, FOCUS B + and FO-
CUS B -) by the motor driver IC (IC951), and are then used to
microstep-drive the stepping motor for focusing operation.
Detection of the standard focusing positions is carried out by
the ASIC (IC101) detecting the signal (FOCUS_PI_E) from
the photointerruptor inside the lens block.
4-2. Zoom drive
The 16-bit serial data signals (LENS_SDI) and (LENS_SCLK
and LENS_EN) which are output from the ASIC (IC101) are
used to drive (ZOOM A +, ZOOM A -, ZOOM B + and ZOOM B
-) by the motor driver IC (IC951), and are then used to
microstep-drive the stepping motor for zooming operation.
Detection of the standard zooming positions is carried out by
the ASIC (IC101) detecting the signal (ZOOM_PI_E) from the
photointerruptor inside the lens block.
4-3. ND filter
The 16-bit serial data signals (LENS_SDI) and (LENS_SCLK
and LENS_EN) which are output from the ASIC (IC101) are
used to drive (ND + and ND –) by the motor driver (IC951),
and then the ND filter is inserted into and removed from the
beam path.
4-4. Iris drive
The drive method is a galvanometer type without braking coil.
The output from the hall sensor inside the lens is amplified by
the Hall amplifier circuit inside the IC971 lens drive IC, and the
difference between the current and target aperture determined
by the resulting output and the exposure amout output from
the ASIC (IC101) is input to the servo amplifier circuit (IC971)
to keep the aperture automatically controlled to the target ap-
erture. The lens aperture control signal is output from IC971
and is input to lens drive IN5A of IC951. IC951 functions as
the driver for driving the lens.
4-5. Shutter drive
Reverse voltage is applied to the above aperture drive coil to
operate the shutter. When the shutter operates, the OC_EN
and OC_CONT signals are maintained at a high level, it is
input to IN5A of IC951 with low level.
At the same time the SHUTTER + signal that is output from
the ASIC (IC101) becomes high (input to IN5B of IC951) and
the shutter operates. IC951 functions as the driver for driving
the lens.
5. Video Clip Recording and Playback
5-1. Recording
The signal from the camera block is input to IC101 (ASIC). The
data that is input to the ASIC is input to SDRAM, and converts
this data to encoded MPEG4 data, after which it is written in
sequence onto the SD card as streaming data. At this time,
the audio signals that are input to the built-in microphone are
converted into digital data by the audio CODEC IC of IC181,
and they are then input to ASIC. The audio data is then en-
coded (AAC), and then it is written in sequence onto the SD
card together as streaming data with the image signals de-
scribed above.
5-2. Playback
The data is read from the SD card, and the encoded data is
decoded into image data where it is displayed by the LCD or
on a TV monitor. At the same time, the audio data is also de-
coded, and is input to IC181 as digital data. D/A conversion is
carried out at IC181, and the sound is then output to the speaker
or to the LINE OUT terminal.
6. Audio CODEC Circuit (IC181)
The audio signals from the microphone are converted into 16-
bit digital data. AD conversion is carried out at a maximum
sampling frequency of 48 kHz.
During audio playback, the 16-bit digital data is converted into
analog signals and these are output to the speaker or line out
system. DA conversion is carried out at a maximum sampling
frequency of 48 kHz.
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