Handheld projector
A handheld projector is an image projector in a handheld device. It was developed as a computer display device for compact portable devices such as mobile phones, personal digital assistants, and digital cameras, which have sufficient storage capacity to handle presentation materials but are too small to accommodate a display screen that an audience can see easily. Handheld projectors involve miniaturized hardware, and software that can project digital images onto a nearby viewing surface.
The system comprises five main parts: the battery, the electronics, the laser or LED light sources, the combiner optic, and in some cases, scanning micromirror devices. First, the electronics system turns the image into an electronic signal. Next, the electronic signals drive laser or LED light sources with different colors and intensities down different paths. In the combiner optic, the different light paths are combined into one path, defining a palette of colors. An important design characteristic of a handheld projector is the ability to project a clear image on various viewing surfaces.
History
Major advances in imaging technology have allowed the introduction of hand-held type video projectors. The concept was also introduced by Explay in 2003 to various consumer electronics players. Their solution was publicly announced through their relationship with Kopin in January 2005.Insight Media market research has divided the leading players in this application into various categories:
- Micro-display makers
- Light source makers
- Module makers, 3M Liquid crystal on silicon )
In 2011, Texas Instruments DLP announced improved chipsets that enable brighter images, and LED advances were such that pico projectors using that technology were also increasing in brightness. The DLP chip sets are designed to enhance image brightness without increasing power usage for both WVGA devices, such as mobile phones, and VGA devices, such as digital cameras and camcorders. The chip sets have the ability to project an image up to on any surface in optimum lighting conditions.
In 2014 Texas Instruments DLP's imagers occupied a significant portion of the handheld projector market share. In combination with Osram's Ostar series LEDs optical engines based on DLP technology have achieved over 15 lumens per watt for high brightness applications and over 20 lumens per watt in low brightness applications.
Technologies
Three major image technologies for micro projectors are commonplace:- Texas Instruments's Digital Light Processing
- MicroVision, Inc.'s laser beam-steering
- LCoS manufacturers including Syndiant, Himax, Micron Technologies and Omnivision can usually supply companies with both LED and laser versions.
Each method has advantages and disadvantages. For example, while DLP typically has slightly lower resolution than their LCoS counterparts due to the tiny mirrors used in DLP technology, 3-LED DLP projectors are generally regarded as having a higher contrast, better efficiency and lower power consumption as opposed color-sequential LCoS units and better color quality than white LED LCoS units. Laser scanning projectors such as Microvision's ShowX and AAXA's L1 offer very good color gamut and low power consumption due to the use of lasers as the light source and also present an image that is always in focus. However, high speckle noise along with thermal instability in the image remains a major challenge, primarily due to the pumped green laser. The new "Direct Green Laser" technologies that replace the "pumped green laser" in next generation laser projectors, in combination with improved hardware optics, MEMS Mirror designs and other operational methods, are being deployed or are under development. Speckle noise should be reduced significantly, and thermal issues and power consumption greatly reduced.