Ricoh D082 MPC7501 V-C3

Images printed with the GW controller may show a "halo" effect when printing in 2-bit mode (1800x600dpi) and in 4-bit mode (9600x600dpi).

Problem

• This problem is most visible when text is overlaid onto halftone areas in 2-bit mode or 4-bit mode. The greater the difference in image density between text and halftone areas, the more noticeable the halo effect.
• This problem is also evident when the mode is changed to 2-bit mode. (The default dithering pattern for 2-bit mode is designed to improve gradation, but this can also make the halo effect more visible.)
• This problem is a product limitation for this model, as announced in the SLG (User/Sales/Service Remarks #12).

Solutio

The following solution is only effective when using the GW controller. There are two ways to reduce the halo effect:

1. Print out the image using 1-bit mode (600x600dpi) instead, or
2. Change the dither pattern used in 2-bit mode (1800x600dpi). As mentioned above, the default dither pattern for 2-bit mode is provided to improve gradation. However, there is one more dither pattern (“Low halo effect dither”) that can be selected to reduce the halo effect.

Procedure: To Change the Dither Pattern for 2-Bit Mode

Do the following procedure manually to change the dither pattern used in 2-bit mode to “Low halo effect dither”.

1. Confirm that the Printer/Scanner firmware is Ver1.00.1 (D3765902A) or newer.
2. Execute SP5801-008 (Memory Clear Printer Application). When you execute this SP, the following will be reset to factory settings:
   • The gamma curve adjusted at the last Printer ACC execution.
   • All Group SP1000 settings in Printer SP mode, which includes SP1104 (Gamma Adjustment) and SP1106 (Toner Limit).
3. When you see the “Completed. You have to reboot.” message, turn the machine on.
4. Open Printer SP1001-002 (Bit Switch – Bit Switch 2 Settings).
5. Touch the “6” key, and then the [#] key on the operation panel. The LCD display will change:
   Before (default): 00000000 (0) [00H]
   After (Low Halo Effect Dither): 01000000 (0) [40H]
6. Exit Printer SP mode, and then turn the main power switch OFF and ON.
7. Execute Printer ACC using Test Pattern 2 (1800X600dpi).
   Now, when the user selects 2-bit mode (1800x600dpi) in the printer driver, the Low Halo Effect
   Dither function will be applied automatically.

Procedure: To Restore the Default

To change the dither pattern for 2-bit mode back to the default pattern, do this procedure.

1. Execute SP5801-008 (Memory Clear Printer Application).
2. Cycle the machine off/on.