Akira Kurozuka

Speaker system with image projection screen

A speaker system has an acoustic diaphragm and an image projection screen provided on a surface of the diaphragm integrally therewith so as to enable the user to enjoy both realistic image on the screen and powerful sound reproduced through the diaphragm. The rear surface of the diaphragm is closed at a peripheral portion thereof while the central portion of the rear surface of the diaphragm is opened to the exterior, so that the speaker system can provide a high level of reproduced sound pressure in low-pitched region, while the thickness of the speaker is reduced remarkably. The diaphgram can be driven by a plurality of driving units so that the speaker system can operate only with an ordinary stereophonic amplifier. The diaphragm can be composed of a pair of diaphragm elements capable of vibrating independently of each other and the screen may be integrally and commonly attached to the surfaces of these diaphragm elements in such a manner as to allow the diaphragm elements to vibrate independently of each other, whereby the speaker system can operate in stereophonic mode. Any variation in the acoustic characteristic attributable to variation in the condition of installation is compensated for by a change in the ratio of the opened area of the rear surface of the diaphragm to the whole effective vibration area or by a selective provision of a sound absorbing member on the rear side of the cabinet.

Compact Intracavity Green Light Source with Wide Operation Temperature Range Using Periodically Poled Mg:LiNbO3

A compact and high power green-light source has been developed in diode-pumped solid-state laser based on periodically poled Mg:LiNbO3 (PPMgLN). Optimization of the PPMgLN length in Nd:YVO4 intracvity can achieve wide operation temperature range over 30 °C with maintaining high conversion efficiency. Based on this result, we demonstrated 3 cm3 laser module which generated continuous-wave 0.7-W green light with wall-plug efficiency as high as 11.8%.

L‐9: Late‐News Paper: Laser Projection Display with Low Electric Consumption and Wide Color Gamut by Using Efficient Green SHG Laser and New Illumination Optics

air-cooled RGB lasers including a compact and efficient green SHG laser and new illumination optics for speckle noise reduction, we developed advanced laser projection engine. A prototype of laser rear projection display with low electric consumption (about 50W) for light sources and wide color gamut (137%NTSC) was realized. 1. Introduction the last decade, several different micro-display technologies (LCD, DMD and LCOS) have been developed and projection displays captured the large screen market for business and home theater. Most projection displays are now using lamps as light sources, such as high-pressure mercury lamps and metal halide lamps. Laser light sources are attractive for projection displays. Projection displays based on RGB lasers can provide extremely wide color expression with the narrow spectrum of lasers. Due to small etendue, laser lights are projected with high efficiency. Lasers have longer life time and faster response time than lamps. As high brightness and high power efficiency of lasers contribute to downsizing systems and improving electric efficiency, laser projection displays will find wide applications (1-3). However, for realizing laser displays there are two problems. The one is a suitable green laser with high efficiency, high power and compact size. As there are no green diode lasers and conventional green lasers for high output power need big mechanisms such as water-cooling devices, it is difficult to downsize and to decrease electric consumption. The other problem is an interference phenomenon called speckle. As lasers have high coherency, speckle noises are superposed on projected images (4). We overcome these problems and demonstrate a laser rear projection display with low electric consumption.

Loading mechanism of DVD-RAM drive

We have developed a loading mechanism of DVD-RAM drive for DVD-RAM, PD, DVD-ROM, and CDs. To load both a cartridge and a bare disc, a pair of disc holding members is equipped in a cartridge holder. The front half of the cartridge holder is drawn out of the drive, and a cartridge or a disc is inserted from the front, and so the drive can be used in both horizontal and vertical setup directions. The drive mechanism height is minimized to 31.6 mm by pulling the cartridge holder into the drive after opening the cartridge shutter. It provides enough space for the electric circuit board below the mechanism in the height of 41.3 mm of the half height drive. When a disc is inserted, the cartridge holder is pulled into the drive without pushing the cartridge holder using sensors in the cartridge holder.