빠른 충전시간을 가지는 포토플래시 캐패시터 충전기와 광량조절기의 설계 : Design of a Fast Charging Photoflash Capacitor Charger and a Light Intensity Controller
- 발행기관 고려대학교
- 발행년도 2008
- 학위수여년월 2008. 2
- 학위명 석사
- 학과 대학원 전자전기공학과 전자전기컴퓨터공학전공
- 식별자(기타) DL:000018611806
- 서지제어번호 000045438348
초록/요약
It requires high voltage over 300V for flashing the Xenon bulb commonly used in digital camera and camera phone. For that reason, it requires photoflash capacitor and charging circuit. Nowadays, the photoflash capacitor charger of micro-controlled flyback converter type is the most popular charging circuit because of its low power and small area characteristic. The most important aspects of this structure are charging time and efficiency. Fast charging time is an advantage that user can have short latency time. And control logic block is the most important block to decide the charging time of the photoflash capacitor charger. To address this issue, various design techniques have been developed to fast transient response and to have high efficiency for flyback converter. This paper proposes the architecture that the control logic block approaches for fast charging with high efficiency of photoflash capacitor charger. However, for faster charging time, the photoflash capacitor charger must select large peak current of transformer primary side current which gives a bad effect of battery life. So, for user convenience, it can control widely current limiting by using wide range current limiter. The camera flashes the photoflash to take its picture in dark place. Generally IGBT driver is used to flash the photoflash. The present research points of IGBT driver are driving current, rising and falling time, area and power. The photographer can get the picture of the various colors to want through controlling brightness of a photoflash. However, the brightness of a photoflash light is fixed in the same operating voltage. Therefore it is impossible to control brightness of light. But it is possible to adjust the intensity of photoflash light to control the exposure time of photoflash light. To control the exposure time of photoflash light is seen like adjusting light brightness to take film of a camera. It is possible to control the exposure time of photoflash to control pulse width duration of IGBT driver. So, this paper proposes light intensity controller for that issue. Proposed photoflash capacitor charger and light intensity controller was fabricated using 0.35um high voltage CMOS technology. Proposed photoflash capacitor charger has over 75% high efficiency and fast charging time of 3s to 300V VOUT at 3.3V VBATT, 1.2A ILIM. And it has wide current limiting range from 0.4A to 1.6A. In proposed light intensity controller case, there was the pulse width duration 0.14ms in the VMS=0.5V, 1.16ms in the VMS =2.0V. And in the strong light (Photo diode current = 30uA), the pulse width duration is 0.8ms. In the Weak light (Photo diode current = 15uA), the pulse width modulation is 1.6ms.
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