ADNS-3090 Datasheet, PDF (26/38 Pages) Pixart Imaging Inc. – High-Performance Optical Mouse Sensor

PixArt Imaging Inc.
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SQUAL
Access: Read
Address: 0x05
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 10-bit unsigned integer.
USAGE: SQUAL (Surface Quality) is a measure of ¼ 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 *4
The maximum SQUAL register value is 169. 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 250 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).
100
90
80
70
60
50
40
30
20
10
0
1
SQUAL Values (White Paper)
Z =2.4mm, Circle@7.5" diameter, Speed = 6ips
101 201 301 401 501 601 701
Counts
Figure 26. Squal values (white paper)
SQUAL vs Z (White Paper)
Resolution = 3500cpi, Circle@7.5" diameter, Speed = 6ips
100
90
80
70
60
50
40
30
20
10
0
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4
Distance from Lens Reference Plane to Navigation Surface, Z (mm)
Avg-3sigma
Avg
Avg+3sigma
Figure 27. 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: [e-mail]
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