Ricoh A156 - Page 71

- Forced V
L
Detection -
When forced V
L
detection (SP3-105) is executed, the CPU stores the V
L
reference value (V
REF
) in memory (see Fig. 19).
V
REF
= initial V
LP
/V
LG
- Every 1,000 copies -
After the forced V
L
detection, V
L
detection is performed at the end of every
1000 copies. The V
LP
/V
LG
value at that time is called V
DAT
.
V
DAT
= current V
LP
/V
LG
- During Copying -
The CPU compares the latest V
DAT
with the latest V
REF
and applies a V
L
correction to the exposure lamp voltage as shown below.
Table 13. V
L
Correction
ID Correction Lamp
Correction
Voltage
±0 V
–40 V –80 V
V
DAT
/V
REF
x 100 (%)
146 ~ 156 ~ 168 ~ –1 V
101 ~ 145 101 ~ 155 101 ~ 167
±
0 V
~ 100 ~ 100 ~ 100 +1 V
In general, the lamp will be dimmed slightly if the V
LP
pattern reflectivity has
increased significantly (the V
LP
pattern is paler), and made brighter if the
reflectivity has decreased (the V
LP
pattern is darker).
V
L
correction also depends on the current V
SP
pattern ID correction that is
being used (see Image Density Control - ID Correction for the V
SP
pattern).
For example, taking the ID correction to be zero for now, if V
DAT
/V
REF
is
150%, the lamp correction will be -1V (made slightly dimmer). Using the
same example, but with an ID correction of -40V, the correction will be 0 V
this time.
ID correction
0 V
–40 V
–80 V
Detailed
Descriptions
STM 2-23 A156/A160/A162