Toshiba DP120F, Service Manual

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March 2000 © TOSHIBA TEC 7-31 DP120F/DP125F Circuit Description
3.2 Scanning Control Circuit
The scanning control circuit consists of the CIS, DSC (IC59), PTC GA (IC45), DMAC GA (IC16),
PIX-DRAM (IC25), I/OP-2 GA (IC-48), CODEC (IC51), and other peripheral devices. The CIS
is controlled by the DSC to scan documents and the image data (raster data) is converted by
the PTC GA and CODEC.
The CIS lights the LED array when the LEDON signal of the I/OP-2 GA goes HIGH. It scans
the LED array’s light reflected by a document and converts it to an analog image data. Since
light is reflected extensively by a white part of the document and then more light is sensed by
the sensor array, the amplitude of the analog image data becomes larger.
The DSC reads the analog data output from the CIS as an SIG signal according to the timing of
the XCLK signal and XSI signal, and converts it to digital data by the simple binarizing process
or error diffusion method. Then it transfers the MVSDA signal as serial data to the PTC GA
together with the MVSCK signal and MVSENX signal.
The PTC GA converts serial image data to 16 bits of parallel image data (raster data). Then the
parallel image data is transferred in DMA mode to the PIX-DRAM on PXD0-15 through CH2 of
the PIX-DMAC of the DMAC GA.
Fig. 7-3-2
07-03-02
Signal Name Type Active Description Destination
LEDON O H LED Array Lighting Signal CIS
XCLK O - CIS Drive Clock CIS
XSI O - Line Synchronizing Signal CIS
SIG I - Analog Image Data DSC
MVSCK O - Image Data Transfer Clock PTC GA
MVSENX O L Image Enable Signal PTC GA
MVSDA O - Serial Image Data PTC GA