Laser display technology
The laser display takes the laser as the light source, makes full use of the characteristics of laser wavelength selection and hyperspectral brightness, so the display image has a larger gamut, its gamut coverage can reach more than 2 times of phosphor powder, can reach more than 90% of the color space that the human eye can recognize, and has a very high color saturation.Laser TV USES semiconductor to pump solid laser working material to produce red, green and blue wavelength continuous laser as the light source of color laser TV, and control the three-color laser scanning image by TV signal.The laser display system consists of laser, modulator, optical deflector and screen.After the system receives the video signal, the red, green and blue image signal and frame synchronization signal are separated from the signal.After processing, the three-color signal control three-color semiconductor laser diode array, so that the corresponding intensity of light emitted, color modulator output, under the control of the frame synchronization signal, through the optical deflector, beam scanning, shoot to the receiving screen, form an image.Red, green and blue laser are the three primary color light sources for color display. Compared with fluorescent light source, the beam quality and efficiency are higher. The balance of the three primary colors can be achieved without the green shadow generated by fluorescent light source and the yellow shadow generated by incandescent light source.
(1)The basic principle of LCRT is to replace the cathode ray picture tube (CRT) with a semiconductor laser to achieve a new type of display device.In addition to using a semiconductor laser instead of a fluorescent panel, the LCRT is essentially a standard cathode-ray tube for projection.The two sides of the semiconductor material are adjacent to the mirror surface to form a laser resonator and are combined with a substrate to form a laser panel.Scanning a laser panel with an electron beam produces a laser at the spot where the beam is bombarded.The physical mechanism of the excitation is similar to that of the fluorescent CRT, except that it produces a laser instead of fluorescence.LCRT resolution can be very high, when the CRT current is 2mA, the electron beam diameter is 25 m, the laser beam diameter is slightly smaller than the electron beam spot diameter is 20 m, the current laser panel grating size is 40mm×30mm, it can give 2000×1500 pixels.At present, efforts are being made to the direction of real cinema screening quality.LCRT is also an ideal cinema projection light source, which does not produce the infrared and ULTRAVIOLET glare that damage the film.It is expected to extend the projection life of the film, so it can be used as a compatible digital/film projector.
(2) is the laser light valve display, the basic principle is that the laser speed is only used to change some materials (such as liquid crystal, etc.) of the optical parameters (refractive index or transmittance), and then use another light source to change the optical parameters and constitute the image projected on the screen, so as to achieve the image display.The principle of laser beam writing is: the near-crystal phase liquid crystal with positive dielectric anisotropy is sandwiched between two glass substrates with transparent electrodes (one of which is coated with laser absorption layer) to form a liquid crystal light valve.The YAG laser beam focusing at about 10 m is irradiated to the liquid crystal light valve, which is absorbed by the absorption film and converted into heat energy and transmitted to the liquid crystal.As the temperature rises, the irradiated liquid crystals change from near-crystal phase to isotropic liquid through nematic phase.When the laser beam moves to other place, the temperature of liquid crystal drops sharply, and the phase transition from isotropic liquid to columnar liquid crystal to near-crystal phase occurs.Due to rapid cooling, a focal cone structure with light scattering is formed during the phase transition, which remains until the image is erased.
(3) It is an intuitive (point scanning) TELEVISION laser display, which is a signal modulated RGB three-color laser beam directly through mechanical scanning method to scan the deflection onto the display screen.Direct laser scanning laser TV takes advantage of the high color purity of laser and larger color gamut than general color TV.The images displayed are more vivid and realistic.The direct scanning mode is different from the optical system imaging. It has no limit of focus range and can be displayed on any reflective object, so it can be displayed on buildings, water curtain (water curtain TV), smoke (air display) and other special effects.
The key problem of laser display technology is the problem of light source.Through a semiconductor manufacturing process, design the structure of semiconductor, and then through MOSD extension out the source of the semiconductor, through the collapse into a chip, the combination of produce red, green and blue laser, passes through the beam shaping, shimming, coherent, and a series of complex optical processing, input to display system, work it out through the display system, forming a television or other applications.
The laser light source is completely different from the traditional light source at present, mainly from several aspects:
(1) In terms of the spectrum degree, its spectrum width is far less than half a meter. Such a high spectrum degree of light is different from the traditional system in terms of the whole color system management and control.
(2) The laser is extremely bright, and it can contain the intensity of more than 10,000 watts or even 100,000 watts of light.
(3) Excellent directionality. The luminescence characteristics of the light transmitted in space are completely different from those of the general light source.
The design of optical systems for such a light source revolutionizes the way we do lighting in terms of lighting patterns and beam control.At the same time, laser light sources are extremely polarized, with a polarization of thousands of meters, which is a great raw material saver for polarization-related display technologies like LCD, and its contrast ratio is much higher than current polarization levels.Unlike light bulbs and leds, laser light sources can achieve high efficiency of light energy on a very small chip due to their optical properties.The horizontal axis is the size of the chip, and the vertical axis is the utilization of light energy.With the decrease of chip size, the utilization efficiency of light source is relatively low.