PixArt Imaging Inc.
Track-on-Glass Laser Sensor
SQUAL
Address: 0x07
Access: R
Reset Value: 0x00
Bit
7
6
5
4
3
2
1
0
Field
SQ7
SQ6
SQ5
SQ4
SQ3
SQ2
SQ1
SQ0
Data Type: Upper 8-bits of a 11-bit unsigned integer.
USAGE:
The SQUAL (Surface quality) register is a measure of the number of valid features visible by the sensor in the
current frame. Use the following formula to find the total number of valid features.
Number of Features = SQUAL Register Value * 8
The maximum SQUAL register value is 40(Dec) (0x28). 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 900
sequentially acquired SQUAL values, while a sensor was moved slowly over white paper.
SQUAL Value (White Paper) after SROM download
At Z = 2.4mm, 1100cpi, Circle@7.5" diameter, Speed=6ips
200
160
120
80
40
0
1
56 111 166 221 276 331 386 441 496 551 606 661 716 771 826 881
Count
Figure 18. SQUAL Values (White Paper)
Mean SQUAL vs Z (White Paper) after SROM download
1100cpi, Circle@7.5" diameter, Speed=6ips
200
160
120
80
Avg-3sigma
Avg
Avg+3sigma
40
0
0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
-
Delta from Nominal Focus (mm)
Figure 19. Mean SQUAL vs. Z (White Paper)
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
25
PIXART [ PIXART IMAGING INC. ]
