PixArt Imaging Inc.
ADNS-7550 Integrated Molded Lead-Frame DIP Sensor
SQUAL
Address: 0x06
Access: Read
Bit
Reset Value: 0x00
7
6
5
4
3
2
1
0
Field
SQ
SQ
SQ
SQ
SQ
SQ
SQ
SQ
0
7
6
5
4
3
2
1
Data Type: Upper 8 bits of a 9-bit unsigned integer.
USAGE: SQUAL (Surface Quality) is a measure of the number of valid features visible by the sensor in the current
frame.
The maximum SQUAL register value is 242. Since small changes in the current frame can result in changes in SQUAL,
variations in SQUAL when looking at a surface are expected. The graph below shows 800 sequentially acquired SQUAL
values, while a sensor was moved slowly over white paper. SQUAL is nearly equal to zero, if there is no surface below
the sensor. SQUAL is typically maximized when the navigation surface is at the optimum distance from the imaging
lens (the nominal Z-height).
SQUAL Value (White Paper)
At Z=0mm; Circle = 7.5" diameter; Speed=6ips
200
150
100
50
0
1
56 111 166 221 276 331 386 441 496 551 606 661 716 771 826
Count
Figure 22. SQUAL Values at 800cpi (White Paper)
Mean SQUAL vs Z (White Paper)
At Z=0mm; Circle = 7.5" diameter; Speed=6ips
200
150
100
50
Avg-3sigma
Avg
Avg+3sigma
0
1.6 1.8
2.0 2.2 2.4 2.6 2.8
Delta from Nominal Focus (mm)
3.0 3.2
Figure 23. Mean SQUAL vs. Z (White Paper)
All rights strictly reserved any portion in this paper shall not be reproduced, copied or transformed to any other forms without permission.
PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
22
PIXART [ PIXART IMAGING INC. ]
