Main control unit

OVERVIEW

This scanner is controlled by a 80C186 MPU. This scanner consists of a ROM as a program area, internal registers, an external RAM as a work area, gate arrays for the MPU peripheral and video circuits, dither processing and γ conversion RAMs, and error diffusion.

Interface control

SCSI-2 interface

SCSI (small computer system interface) circuit consists of SPC (MB86601A), VCEP (OTI95C71/20) and a glue ASIC. The scanned image data are transferred to interface circuit as video interface. The interface circuit converts internal video interface to SCSI interface via compression, if required. SCSI interface transferes data 1.5MB/s in Asynchronous transfer, 4.0MB/s in Synchronous transfer following to SCSI-2 standard. The VCEP compresses the binary image data in MH, MR, MMR algorithm defined by CCITT G3, G4. See Chapter 3 for details of SCSI interface.

Resolution

The basic resolution of this scanner is 200dpi. The resolution can be changed to 240, 300, or 400dpi from the host computer or the operator panel.

The resolution in the subscanning direction is achieved by changing the document transport speed.

When the image processing circuit II (IPC II) option is installed, the linear density is changed by setting the parameter to its internal circuit.

Video amplifier and driver section

This section consists of a CCD drive circuit, a video amplifier circuit, a white-black level correction circuit, sensors, and also control circuits for the stepping motor, heater, and lamps.

M3099GX/GH OEM Manual

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