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1-2-1. Startup operation
When batteries are loaded or the AC adaptor is connected, a 3.0V voltage for the sub-CPU is generated by U402 and supplied to the sub-CPU (U405).
When the POWER switch (S800) is turned on in this status, the camera switches to the boot-up sequence.
The sub-CPU (U405) conducts the power on control until the main voltage supplied to the DSP (U901) and other parts is supplied. When the AC
adaptor is connected, it is identified and turns on the power. If the AC adaptor is not connected, the battery voltage is checked and the power only
turns on if the voltage is strong enough to turn it on.
Once the power is turned on, the power off operation is conducted by the DSP (U901) exchanging data with the CPU (U405) to check the battery
voltage information, and if the voltage is below the stipulated value a command is issued to turn the power off with the POWER switch.
1-2-2. Power off operation
The power off operation is conducted by the DSP (U901) exchanging data with the sub-CPU (U405) to check the battery voltage information, and if
the voltage is below the stipulated value a command is issued to turn the power off with the POWER switch.
In the standby mode after the power has turned off, only the calendar function of the sub-CPU (U405) operates and the camera stands by for the
power to be turned on next. The calendar function remains operating for a specific amount of time even if the AC adaptor is disconnected and no
batteries within camera, the camera's built-in coin battery (BT1) keeps operation tell a certain fixed time.
1-2-3. Image capturing mode
The DSP (U901) switches to the image capturing mode when the mode dial is set to the image capturing status. When the shutter button is pressed in
this status, the DSP (U901) issues the image release command to the CCD driving IC (UB50) in order to obtain the image from the CCD (UB10),
and the image signals from the CCD (UB10) are converted into digital signals by the AD converter (UB11) and output to the DSP (U901). When the
image data is input to the DSP (U901), the DSP (U901) conducts the operation for processing the signals, converting them into YCrCb signals then
into JPEG format and writing this on the SD card. The DSP (U901) uses the SDRAMs (U300 and U301) for the signal processing operations and for
temporary data storage.
1-2-4. Display mode
The DSP (U901) switches to the display mode when the mode dial is set to the display status. Data is loaded from the SD card and the image is
displayed on the LCD or EVF. When a video cable is connected, the data is only output from the video cable. The DSP (U901) converts the SD
card's images from JPEG to YCrCb format in order to display them on the LCDs. The SDRAMs (U300 and U301) are used at this time.
1-2-5. Lens module control
The lens module consists of shutter, aperture and focus motors. A current drive motor is used for the shutter, step motors are used for the aperture,
focus and zoom. The initial positions of the focus and zoom are determined by a photo interruptor inside the lens module. The step motor determines
the focus position based on this. The pulses applied to the motor are applied to the motor drive IC (U505) from the DSP (U901) and amplified to
drive the lens motor.
1-2-6. Auto focus/ Auto exposure (AF/AE)
The results of several pre-captures are processed in the DSP (U901) in order to determine the optimum focus position and aperture/shutter time.
When taking still pictures, the AE/AF operation is only performed when the shutter button is pressed half way.
1-2-7. Auto white balance
The DSP (U901) calculates the RGB values from the raw data output from the AD converter (UB11), the ARM performs calculations to obtain the
gain comparisons of the RGB color signals, and the CCD1 module in the DSP (U901) is controlled.
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