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timing is shown in Figure 29, and in slightly more detail in Figure

41.

Illumination Mode 3 is similar to Illumination Mode 2, except that

the LAMP outputs for all three colors are turned on and off every

line. Illumination Mode 3 timing is shown in Figures 30 and 31.

These modes are in operation whenever the chip is powered on

and not in standby mode. For example, the LAMP outputs in Fig-

ures 29 and 30 keep pulsing whether the LM9830 is in the Idle,

Paper Feed, or Scanning states. This eliminates light amplitude

variations due to the lamp/LEDs warm-up characteristics. Since

the LAMP pulses are synchronized to the TR pulse, which is

determined by the horizontal pixel counter, this means that the

pixel counter is constantly running, and any new scans can only

be started by waiting for the next new line (the next Red line in the

case of Illumination Mode 2).

4.2 CCD/CIS Control Block

This function generates the clock signals necessary to control a

CCD or CIS sensor. The LM9830 features:

• Independent control over the polarity (inverting or noninverting)

of the input stage to accommodate CIS or CDS signals.

• Ability to turn off CDS. When CDS is on, traditional CDS is per-

formed. When CDS is off, the signal is sampled at the Sample

Signal point, but the internal reference is used for the Sample

Reference voltage (not a point on the input signal itself).

• The CP1 output supplies the CP pulse needed on some popu-

lar Toshiba CCDs. This looks and acts just like another, inde-

pendent RS pulse.

• A CP2 output is another independent pixel rate pulse that (if

needed) can be programmed to supply an additional clock.

• CCD clock signals RS, CP1, CP2 are reset when Line Ends

• The internal Clamp signal is reset with Optical Black Pixels End.

• TR1 and TR2 pulse widths are always the same width, as deter-

mined by Register 0E.

• The TR-Ø1 guardband may be equal to 0, causing TR and Ø1

to go high simultaneously and low simultaneously (Figure 32).

This is a requirement of some Canon CIS sensors.

• CIS TR1 Timing Mode 1. In this mode the TR1 pulse is exactly

one Ø clock long, occurring on the rising edge of Ø1. The TR1

pulse width and guardband settings are ignored. For Dyna CIS.

• CIS TR1 Timing Mode 2. In this mode the TR pulse is again

equal to 1 Ø period, but now it is centered around Ø1. The TR

pulse width and guardband settings are ignored. For Canon

CIS.

• To prevent sensor saturation, the LM9830 is always clocking the

CCD/CIS, except when it is in Reset or Standby (Register 7 bit

2 or 3 = 1).

• There is a bit for Fake Optical Black Pixels (register 19, bit 2).

This is used with Dyna CIS sensors. In this mode, the RS out-

put pulses once inside the TR1 pulse, then is held high until the

end of the optical black pixels. The TR1 pulse is extended until

Figure 29: Illumination Mode 2

LAMPG

LAMPB

LAMPR

Figure 30: Illumination Mode 3 (grayscale)

LAMPG

LAMPB

LAMPR

Figure 31: Illumination Mode 3 (green only)

LAMPG

LAMPR (LAMPR On > Line End, LAMPR Off < Line End

LAMPB (LAMPB On > Line End, LAMPB Off < Line End

TR Pulse same as first clock pulse

ø1

Figure 32: TR-Ø1Guardband Can Be Equal To 0

Figure 33: CIS TR1 Timing Mode 1

Dummy

Pixels

TR1

Ø1

Transfer

Phase

Line

ø1 inside TR1 pulse

TR1

ø1

tø1/4

tø1

Figure 34: CIS TR1 Timing Mode 2

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