VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C1
SoC Design of An Auto-Focus Driving Image Signal Processorfor Mobile Camera Applications
Presenter:梁正勳Number:97662003
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 2
Introduction Auto Focus Camera System SoC Implementation Experimental Results Conclusions
Outline
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 3
Index Terms
Image Signal Processor (ISP) Auto Focus(AF) Camera system Voice Coil Motor (VCM) AF lens driver
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 4
AF mobile phone camera system
(a) A conventional AF camera configuration
(b) The proposed AF camera configuration
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 5
Auto Focus (AF) Theory
(a) The focusing mechanism
(b) The focusing algorithm
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 6
AF lens driver and Lens
Lens typeDriver type
Factors
Power consumption
AF speedModule
SizeCost
Stepping motor
H-bridge High Slow Big High
VCM DAC Medium Medium Small Low
Piezo motor
H-bridge Low Fast Small Medium
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 7
AF Control Block (AF filter & MCU)
AF block diagram
AF control flow
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 8
A detailed VCM lens module
(a) AF camera module
(b) Focus values
(c) AF lens driver outputs
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 9
AF lens driver
Architecture of AF lens driver
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 10
Shows the architecture
Buffer Amplifier
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 11
Chip Design
(a) The AF camera moduleusing the AF_ISP
(b) The die photo ofthe AF_ISP
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 13
The results of comparison against other
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 14
Experimental Results
(a) defocused image (b) focused image
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 15
Experimental Results
(c) the measured focus values (d) The measured output voltage of the AF (VCM) driver
VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 16
Conclusions
This paper describes an auto-focus driving image signal processor and the AF solution with it.
Phone manufacturers are becoming more cost effective and low power consumption.
We developed the SoC of an AF driving ISP which has all-in-one AF solution, such as AF statistics, AF control and AF lens driver.
In addition, this SoC solution also allows for fast and optimal AF performance of mobile camera applications.