CN102096293B - Optical engine for three-piece liquid crystal on silicon (LCOS) laser projection display - Google Patents

Abstract

The invention relates to an optical engine for laser projection display of a three-piece liquid crystal on silicon (LCOS). The optical engine comprises a red laser, a green laser, a blue laser, three dodging and reshaping systems, an optical core, a three-piece LCOS, a reflecting mirror and a projection objective, wherein the luminescence centers of the three lasers are positioned on the main optical axes of corresponding dodging and reshaping systems; the three optical axes of corresponding dodging and reshaping systems are parallel with one another; three light beams emitted by the three lasers are adjusted into uniform rectangular parallel light beams by the dodging and reshaping systems respectively; two beams of light directly enter corresponding polarization beam splitters, and the other beam of light is reflected by the reflecting mirror and enters a corresponding polarization beam splitter; and polarized light in three colors is finally combined into white light and enters the projection objective by the optical core. The lasers are taken as light sources, generated laser light is small-bandwidth linear polarized light, and a color filter is not used, so that a large number of polaroids are eliminated, cost is lowered, and the utilization ratio of optical energy is increased simultaneously; and the color gamut range, color brightness degree and color fidelity degree of the optical engine are better than those of the optical engine of the conventional optical system.

Description

Optical engine for three-chip LCOS laser projection display

technical field

The invention relates to an optical engine for three-piece LCOS laser projection display, which belongs to the technical field of laser display.

Background technique

After decades of development, projection display technology has gradually matured and been widely used. At present, projection display technologies are mainly divided into four categories: CRT, LCD, DLP, and LCOS. CRT projection display technology has the longest development time and is the most mature technology. However, due to its shortcomings such as low brightness, limited display size, large size, heavy weight, complex adjustment, and long-term display of still pictures will cause burns to the cathode ray tube, it is now rare. Use; LCD projection display technology has developed rapidly in the past ten years. It has the advantages of small size, light weight, simple operation, and low cost, but it has disadvantages such as low light utilization rate and strong pixel sense; DLP projection display technology is currently The only all-digital projection technology, its imaging device is DMD, which has the advantages of relatively high light energy utilization rate, fast response speed, good brightness and color uniformity, small size, and light weight; while LCOS projection display technology combines LCD The advantages of the two projection display technologies, DLP and DLP, have the following advantages: (1) high resolution and delicate image; (2) high aperture ratio, high light energy utilization rate, and high brightness; (3) higher contrast ratio than LCD, up to 2000: 1; (4) Like DLP panels, it can directly reflect light so that the panels are not easy to be burned; (5) No afterimage phenomenon.

No matter what kind of projection display technology, the light source is the key to ensure that the color is vivid and the image is rich in color. On the chromaticity diagram released by the International Commission on Illumination (CIE) in 1931, the triangle area of the laser display color gamut is more than twice that of the traditional CRT color gamut triangle, which means that the color gamut of the laser projection display is wider. The colors that come out are more realistic. In addition, compared with traditional displays, laser displays have the following advantages: ①Because the spectrum of laser is a line spectrum, the color purity and saturation of laser are very high; ②Compared with ordinary displays, in the same size, the same display effect Under certain conditions, the light energy lost by the laser display is low; ③The life of the laser display can reach more than 100,000 hours at room temperature, which has a long life and high reliability; ④The laser display is easy to realize a large-size screen.

To sum up, LCOS-based laser projection display technology is the development direction and inevitable trend of future projection display technology. Theoretically, in the traditional projection display color mixing mechanism, whether it is based on the three-chip LCOS space color mixing technology, or based on the single-chip LCOS using a high-speed rotating motor to drive the color wheel to achieve time color mixing technology, there are 67% of the light energy. Therefore, based on LCOS projection display technology, finding a new color mixing mechanism to reduce the waste of light energy as much as possible is the current top priority in the field of projection display technology.

The Chinese patent "LCOS optical engine system" with the patent number ZL200720310464.8 discloses an LCOS optical engine system, which includes a UHP light source, a light rod, a relay lens group, a dichroic mirror, a reflector, a prepolarizer, Polarizing beam splitter (PBS), LCOS chip, X-type light combining prism and projection lens; The outer sides of the three PBS prisms are respectively equipped with LCOS chips. Although the system realizes the color display of images, the working life of the UHP light source is short, the color filter reduces the utilization rate of light energy, the color gamut of the display system is narrow, and the heat dissipation of the system is complicated. Poor reliability and stability. The Chinese patent No. 200710042362.7 "three-chip LCOS projector optical engine with three-color LED lighting" replaces the UHP light source in the above patent with red, green and blue three-color LED light sources; Three lighting systems with the same structure replace the color separation lighting system in the above patent. This system also realizes the color display of images, but because the LED light source is a surface light source composed of multiple points, this requires its three lighting systems with the same structure to use many devices and complex structures when arranging the light beams. the

Contents of the invention

The object of the present invention is to propose a three-piece LCOS optical engine for projection display with laser illumination and simple optical path structure. the

In order to achieve the above object, the three-chip LCOS laser projection display optical engine of the present invention includes a light source, a projection objective lens, three polarization beam splitters and an X-shaped light combining prism, and an LCOS that is respectively arranged on the outside of the three polarization beam splitters. Composed of optical cores, the light beams emitted by the light source are injected into the projection objective lens through the optical cores, the light sources are red, green, and blue lasers, and three lasers with the same optical structure are arranged between the three-color lasers and the optical cores. The uniform light shaping system that adjusts the laser beams emitted by the corresponding lasers into uniform rectangular parallel beams, the luminous center of the three lasers is located on the main optical axis of the corresponding uniform light shaping system, and the main optical axes of the three uniform light shaping systems are parallel to each other ; After the three beams emitted by the three lasers are respectively adjusted into uniform rectangular parallel beams of appropriate size through the uniform light shaping system, two of the beams of light are directly injected into the corresponding polarization beam splitter, and the other beam of light is reflected by the mirror and then enters the corresponding Polarizing beam-splitting prism, the three-color polarized light emitted from the three polarizing beam-splitting prisms is synthesized into white light by the X-type light-combining prism, and enters the projection objective lens to realize laser full-color display.

Further, the uniform light shaping system includes a beam expansion and collimation subsystem for turning the beam emitted by the laser into a circular parallel light, and a beam shaping and dissipating spot for turning the circular parallel light into a uniform rectangular parallel light system and a conjugate dephaser for speckle dissipation.

Further, the beam expander and collimation subsystem is composed of a biconcave lens and a biconvex lens, and the focus of the biconvex lens coincides with the virtual focus of the biconcave lens.

Further, the beam shaping and dissipating speckle subsystem includes first and second Fourier transform lenses, a micro-rotating motor, a connection plate, a small-angle scatterer and a phase diffraction optical device, and the micro-rotation motor is fixed on the connection plate , the center of the connecting plate is provided with a light-transmitting small hole, and the first Fourier transform lens, the small hole, the phase diffraction optical device and the second Fourier transform lens are successively arranged on the main optical axis of the uniform light shaping system, and the connecting plate is vertical On the main optical axis of the uniform light shaping system, the small-angle diffuser is arranged on a micro rotating motor close to the phase diffraction optical device.

Further, the scattering angle of the small-angle diffuser is less than 1 degree.

Further, the reflector is a single-wavelength dielectric film highly reflective mirror for reflecting green light.

Further, a half-wave plate is provided between the red and blue light polarization splitter prisms and the X-type light combining prism.

Further, the three lasers and the three uniform light shaping systems are arranged side by side on the same plane and on the same side of the LCOS projection optical system.

The optical engine for three-piece LCOS laser projection display of the present invention uses a laser as a light source, and the generated laser light is linearly polarized light with a narrower bandwidth. No color filter is used, a large number of polarizers are saved, and the light is improved while reducing the cost. energy utilization; using the polarization characteristics of the laser, there is no need to obtain polarized light through a polarizing device, which further improves the light energy utilization; using a uniform light shaping system can obtain a relatively uniform, pure color, and high-brightness illumination spot; due to the wide bandwidth of the laser Narrow, adjustable wavelength, the optical engine is far better than the optical engine of the existing projection system in terms of color gamut range, color vividness, and color fidelity, and the system structure is relatively simple.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention;

Fig. 2 is a schematic diagram of a beam expander collimation subsystem;

Fig. 3 is a schematic diagram of a system for beam shaping to eliminate speckles;

Fig. 4 is a schematic diagram of a phase diffraction optical device.

Detailed ways

The optical engine for three-piece LCOS laser projection display of the present invention is shown in Figure 1, comprising a red laser 1, a green laser 2, a blue laser 3, three uniform light shaping systems with the same optical structure, a reflector 13, a red laser Polarizing beam splitting prism 14, green light polarizing beam splitting prism 15, blue light polarizing beam splitting prism 16, red LCOS 17, green LCOS 18, blue LCOS 19, X type light combining prism 20 and projection objective lens 21. The wavelength of the red laser is 635nm; the wavelength of the green laser is 532nm; the wavelength of the blue laser is 447nm; the mirror is a single-wavelength dielectric film high reflection mirror for reflecting green light. The three polarizing beam splitters are cubic prisms with a side length of 25.4mm, which have the functions of polarizing and analyzing at the same time; the X-type light combining prism is a cubic prism with a side length of 25.4mm, which can synthesize three-color lasers into Standard white; all three LCOS measure 0.7 inches (16:9).

The red, green, and blue light polarizing beam-splitting prisms and the X-shaped light-combining prism 20 and the red, green, and blue LCOSs respectively arranged outside the red, green, and blue polarizing beam-splitting prisms form the light core, and each polarization beam-splitting prism is set close to the X-shaped light-combining prism ; There is a half-wave plate between the red and blue light polarizing beam splitting prisms and the X-type light combining prism.

There are three uniform light shaping systems with the same optical structure between the three laser light sources and the optical core of the optical engine, which are used to adjust the laser beams emitted by the corresponding lasers into uniform rectangular parallel beams. The three lasers are used as light sources. The luminous center is located on the main optical axis of the corresponding uniform light shaping system, and the main optical axes of the three uniform light shaping systems are parallel to each other. The three lasers and the three uniform light shaping systems are arranged side by side on the same plane, and are located same side.

The three uniform light shaping systems all include a beam expanding and collimating subsystem for turning the beam emitted by the laser into a circular parallel light, a beam shaping and dissipating speckle subsystem for turning the circular parallel light into a uniform rectangular parallel light, and a A conjugate dephaser for dispersing speckle, which is a phase diffraction optical device. As shown in Figure 2, the beam expander and collimation subsystem is composed of a biconcave lens and a biconvex lens, and the focus of the biconvex lens coincides with the virtual focus of the biconcave lens. As shown in Figure 3, the beam shaping and dissipating speckle subsystem includes a first Fourier transform lens 41, a second Fourier transform lens 47, a miniature rotating motor 42, a connecting plate 45, a small-angle scatterer 43 and a phase diffraction optical device 44. The rotating motor 42 is fixed on the connecting plate 42, and the center of the connecting plate is provided with a light-transmitting small hole 46, and the first Fourier transform lens 41, the small hole 46, the phase diffraction optical device 44 and the second Fourier transform lens 47 are successively arranged on the On the main optical axis of the uniform light shaping system, the connecting plate 45 is perpendicular to the main optical axis of the uniform light shaping system, the small angle diffuser 43 is arranged on the micro rotating motor 42 close to the phase diffraction optical device part, and the small hole 46 is located at the The focal point of the beam of the beam collimation subsystem enables the light energy to completely pass through the small hole 46 and ensures that the connecting plate is perpendicular to the optical axis. The phase-type diffractive optical device 43 is placed behind the small-angle scattering device 44 . The small-angle diffuser can rotate at a high speed for a long time under the drive of the micro motor. The beam passing through the central hole of the mechanical connection plate can weaken the contrast of the laser speckle after passing through the rotating diffuser. The phase diffraction beam shaping device can transform the circular Or the elliptical Gaussian or quasi-Gaussian beam is converted into a uniform rectangular beam, thus achieving the purpose of reducing laser speckle. The small-angle diffuser is made of quartz material with high laser damage resistance threshold, and the scattering angle of the diffuser should not be too large. The scattering angle of the diffuser of the present invention is less than 1 degree.

，其中f为透镜焦距，

为衍射角。所以可通过调节傅立叶变换透镜的焦距按比例缩放频谱面上的光斑空间尺寸。 The phase-diffraction optical device 52 should be placed close to the Fourier transform lens 51. The laser beam is incident on the Fourier transform lens (or phase-diffraction optical device) after passing through the previous system, and L is obtained on the back focal plane of the Fourier transform lens. The required spot distribution is shown in Figure 4. The spatial size of the spot on the spectral plane is determined by the focal length of the Fourier transform lens, and the specific relationship is:

, where f is the focal length of the lens,

is the diffraction angle. Therefore, the spatial size of the spot on the frequency spectrum can be scaled proportionally by adjusting the focal length of the Fourier transform lens.

When in use, the red laser 1, the green laser 2, and the blue laser 3 emit three laser beams at the same time; the three laser beams respectively pass through their respective uniform light shaping systems: firstly, the beam expansion and collimation subsystems 4, 5, and 6 become circular parallel beams. light, after the beam shaping and dissipating speckle subsystems 7, 8, 9 become uniform rectangular parallel light, and then dissipate the speckle again through the conjugate dephasing devices 10, 11, 12, and make the cross-sectional size of the beam suitable for LCOS Uniform rectangular parallel light beams; the red and blue light beams directly enter the corresponding polarization beam splitters 14, 16, the green light beams enter the green polarization beam splitter 15 after being reflected by the reflector 13, and the three polarization beam splitters respectively separate the polarized light of the S state Reflected to LCOS17, 18, 19, at the same time, the signal processing drive system loads the red, green, and blue three-color video signals to the corresponding LCOS respectively, and the light waves modulated by the LCOS are reflected back, and then respectively passed through the polarization beam splitter prism 15 , 16, 17 polarizers, the polarized light of the P state that exits from the three polarization beam-splitting prisms enters the X-type light-combining prism 20 respectively; Color mixing in space is performed to synthesize white light, which is transmitted into the projection objective lens 21 to realize laser full-color display. The optical engine of the present invention can be used for family rear projection TV, or large-screen display in public places such as commercial troubles, stations, docks and the like.

Claims (5)

1. light engine is used in a three-sheet type LCOS laser projection demonstration; Comprise light source, projection objective, by three polarization splitting prisms and an X type light-combining prism and be located at the light that the LCOS in three polarization splitting prisms outsides forms respectively and examine; The light beam that said light source sends is injected projection objective through light nuclear; It is characterized in that; Said light source is the red, green, blue laser instrument; Be provided with the identical even polishing shape system that is used for corresponding laser instrument emitted laser bundle is adjusted into even rectangle parallel beam of three optical textures between this three looks laser instrument and the light nuclear, the luminescent center of said three laser instruments is positioned on the primary optical axis of corresponding even polishing shape system, and the primary optical axis of three even polishing shape systems is parallel to each other; After three light beams that three laser instruments send are adjusted into the suitable even rectangle parallel beam of size through even polishing shape system respectively; Wherein two-beam is directly injected corresponding polarization splitting prism; Another Shu Guang is through getting into corresponding polarization splitting prism after the reflection of catoptron; Three chromatic polarization light from three polarization splitting prism outgoing synthesize white light through X type light-combining prism respectively, get into projection objective, realize the panchromatic demonstration of laser; Said even polishing shape system comprise be used for the light beam that laser instrument sends become circular directional light the beam-expanding collimation subsystem, be used for circular directional light is become the beam shaping dissipation spot subsystem of uniform rectangle directional light and the conjugation of the spot that is used to the dissipate phaser that disappears; Said beam-expanding collimation subsystem is made up of a biconcave lens and a biconvex lens, and the focus of biconvex lens overlaps with the virtual focus of biconcave lens; Said beam shaping dissipation spot subsystem comprises first, second fourier transform lens, miniature rotary electric machine, web joint, small angle scattering device and phase place diffraction type optical device; Said miniature rotary electric machine is fixedly arranged on the web joint; This web joint center is provided with the printing opacity aperture; Said first fourier transform lens, aperture, phase place diffraction type optical device and second fourier transform lens are located on the primary optical axis of even polishing shape system successively; Web joint is perpendicular to the primary optical axis of even polishing shape system, and said small angle scattering device is located on the miniature rotary electric machine near phase place diffraction type optical device.

2. three-sheet type LCOS laser projection according to claim 1 shows uses light engine, it is characterized in that: the scattering angle of said small angle scattering device is less than 1 degree.

3. three-sheet type LCOS laser projection according to claim 1 and 2 shows uses light engine, and it is characterized in that: said catoptron is single wavelength deielectric-coating high reflection mirror, is used for reflect green light.

4. three-sheet type LCOS laser projection according to claim 3 shows uses light engine, it is characterized in that: be provided with 1/2nd wave plates between said red, blue light polarization splitting prism and the X type light-combining prism.

5. three-sheet type LCOS laser projection according to claim 4 shows uses light engine, it is characterized in that: said three laser instruments and three even polishing shape systems are located on the same plane side by side, and are positioned at the same side of LCOS projection optical system.

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