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 12

Experimental Results

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.

VLSI.Lab.,National Changhua University of Education,Taiwan,R.O.C 17

Thank you for your attentions !

The End