CN100443955C - Incoherent optical full-spectrum domain modulation method and its video projection optical machine - Google Patents

Abstract

The invention relates to an incoherent light full-spectrum domain modulation method. The golden light emitted by a light source is collimated and bundled, and projected onto a diffraction grating to expand into a spectrum. The spectrum is projected onto a DMD palette and driven by a video control signal. The DMD palette controls whether each micromirror is turned over to control the amount of light of different wavelengths entering the optical channel, and superimposes the effectively reflected light of each micromirror on a point, representing the brightness and chromaticity of the video signal; the modulation Methods Use a diffraction grating to expand white light into a spectrum or converge the three primary colors on the same DMD chip at the same time; use a fiber collimator to collimate the beam; use a distributed duty cycle control method to drive each on the DMD palette Micro-mirror: All the effective reflected light of the DMD micro-mirror can be bundled to obtain a small beam that directly expresses the chromaticity and brightness of the video signal. High light efficiency and good color reproduction. The invention also relates to a video projection light machine using the method.

Description

Incoherent optical full-spectrum domain modulation method and its video projection optical machine

technical field

The invention belongs to the field of optics, and specifically relates to a control method for brightness and color tone that realizes video rate response to incoherent light and a video projection optical machine manufactured by the method.

Background technique

At present, the representatives of advanced projection technology are LCOS and DLP optical engine. The cost of time-sharing in the single-chip mode is to degrade the optical efficiency by at least 70%. The principle of color mixing is the same whether it is single-chip or three-chip. The narrower the spectral width of the selected R, G, and B is, and the closer the R and B are to the end regions of the spectrum (visible light), the more they can mix and approach the real color gamut. But in fact, people have to make a compromise between effect and efficiency, which is why it is difficult for this type of projection technology to express true colors.

Contents of the invention

The purpose of the present invention is to solve the deficiencies of the existing technology, and to replace the color separation technology in the existing optical machine with the realization of incoherent light full-spectrum domain modulation technology (TMP: True Color Micro-mirror Picture), and to manufacture The performance of the optical engine far exceeds the industry level, and the optical efficiency has the potential to increase by more than 10 times (with excellent white peak performance), and the color reproduction can be improved. Due to the mechanical scanning method, the detailed image quality is also relatively good, and it can be widely used in the field of projection video.

The outstanding feature of the present invention is: use DMD (or LCD/LCOS) to realize the brightness and chromaticity modulation of video signal with duty cycle control mode like palette, while greatly improving efficiency, it has the ability to express any real color Ability. Specifically: in the same 256-level grayscale display mode (corrected by the color correction mode), the number of colors that are several orders of magnitude larger than 256 ³ colors can be achieved, so closer true colors can be obtained.

The technical key of the present invention is: the main composition of this technology: light source (comprising reflective paraboloid), optical fiber collimator, diffraction grating or prism, DMD palette, focusing lens group, diaphragm, mechanical scanning system, projection objective lens, DMD The working principle of the driving circuit is: the panchromatic light emitted by the light source is collimated by the fiber collimator and then bundled, then the stray light is filtered by the diaphragm, and projected onto the diffraction grating (or prism); it is expanded into A full-color spectrum, which is projected onto the DMD palette, and after the brightness and tone control signals are sent to the control circuit of the DMD palette, the turning and holding status of each micromirror on the DMD palette It will be controlled, the proportional relationship of flipping in different areas will be controlled, the amount of light of different wavelengths entering the optical channel will be controlled, and the superposition result of reflected light on the DMD palette will be modulated into different brightness and chromaticity ;Thus, the brightness and hue of the reflected light entering the effective optical path after being reflected by the DMD palette will be modulated to obtain the brightness and chromaticity consistent with the video signal; The projection objective lens is focused on the focal plane; in this method, a diffraction grating (or prism) is used to expand the mixed light (white light with a certain color temperature) into a spectrum; and projected onto the DMD palette, using a fiber optic collimator Collimated light beams; control the DMD palette with the distributed duty ratio control method of brightness and chromaticity; use fiber collimator to collimate the reflected light of the DMD palette; get a direct performance video after beaming Small beams of chromaticity and brightness of the signal. This flip ratio relation (duty cycle) is a two-dimensional function, and the independent variable of function is the plane position coordinate of DMD micromirror, and the acquisition of this function depends on the brightness, chromaticity and this technology special-purpose real of a certain instantaneous video signal. Color temperature correction for color.

The above-mentioned diffraction grating is either a reflection grating or a projection grating, and the stripes of the grating can be straight lines or curved lines or closed curved lines.

The above-mentioned fiber optic collimator is composed of a bundle of optical fibers whose two ends have different diameters. One end with a larger diameter of each optical fiber is bundled together, and the other end with a smaller diameter is also bundled together. The formed The diameter of the optical fiber bundle is larger at one end and smaller at the other end, and a layer of medium with a lower refractive index than the optical fiber filament is covered on the surface of the optical fiber filament.

The above-mentioned distributed duty ratio control of the brightness and chromaticity of the video signal of the DMD palette means that the spectrum irradiated on the DMD is a panchromatic spectrum (white light spectrum), and the light of different frequencies irradiates different colors on the DMD. On the area, controlling the turning and maintaining ratio of the micromirror on the area of each color light on the DMD can control the color and brightness of the mixed output light from the optical path.

This technology and the formation of the spectrum projected on the DMD chip in the optical machine can form a continuous spectrum through gratings and prisms; it can also be irradiated to different areas of the DMD chip through three independent red, blue and green light sources at the same time The color bars formed above.

Description of drawings

[Figure 1] Schematic diagram of incoherent optical full-spectrum domain modulation technology and optical-mechanical optical path.

[Figure 2] Diagram of DMD full-spectrum domain modulation method.

[Figure 3] Structure diagram of optical fiber collimator.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing with regard to preferred embodiment of the present invention:

As shown in [Figure 1], the basic composition of the optical path is: light source (2), fiber collimator (10) and (20), diffraction grating (or prism) (3), DMD modulation/palette ( 1), converging lens group (4) and (5), diaphragm (6) and (7), scanning galvanometer (9), projection objective lens (11), DMD driving circuit (17), etc.; its basic working process It is: the white light emitted by the light source (2) is collimated by the fiber collimator (20) (the effect of collimation is to change a beam of light with a large divergence angle (parallelism difference) into a small divergence angle (parallelism difference) OK)) and then the beam is concentrated by the beam projection lens group (4), after the stray light is filtered by the diaphragm (6), it is projected onto the diffraction grating (or prism) (3) and then expanded into a panchromatic spectrum (press A beam of light separated by a difference in the wavelength of the light, which when projected onto a screen forms color-coded ribbons) expands into distinct regions, projecting the spectrum onto the DMD modulation/palette (1 ) on (will also form colored ribbons arranged by color - the spectrum).

After the brightness/hue adjustment signal is sent to the lead-out electrode of the DMD palette (5), the flipping state of each micromirror on the DMD palette (5) will be controlled, and the proportional relationship of flipping on different areas will be controlled (Local duty ratio), the brightness and color tone of the reflected light entering the effective optical path channel will be modulated (so it is called the color palette vividly), and then collimated by the collimator (10), and the focusing lens group (5) After converging, the scanning is completed by the mechanical scanning system—galvanometer (9), and then focused on the focal plane by the projection objective lens (11).

The necessary and sufficient conditions for the practical application of this system will limit two important indicators: the turnover speed of the DMD will be less than 10 ^-1 microseconds; the collimation degree of the (final stage) fiber collimator (10) will be less than 10 ^-2 degrees, The former - TI (US) has been basically realized; the latter can only be achieved by the collimator in this paper. (See [Picture 2] and [Picture 3] for details)

As shown in [Figure 2]: the structure of the DMD palette (1) is composed of a large number of micro (reflective) mirrors (which have been widely used in DLP projection light machines (US TI company technology)), these mirrors can be independently Driven by the driven circuit (2), the proportional relationship and position distribution of the micromirror's turning and holding can be driven by the driving circuit (2). For different optical path designs, the turning and holding states may be the reflection of the micromirror The light is reflected into the active light channel. At present, the response time of the DMD is on the order of 10 ^-1 microseconds, the flip angle is +/-12°, and the opening width is about 1-2 microns. In the technology of the present invention, the speed of 10 ^-2 microseconds (high-definition signal can be displayed) will be required, but other indicators can be weakened (the flip angle is reduced to +/-3°, the opening width is not important, the size of the micromirror It doesn't matter, the number of pixels is only tens of thousands: this means that more flipping time will be saved, while the distance between the power electrode plates will be reduced, and the area and width of the power electrodes will be increased; The charge reduces the distance at the same time, and the dynamic performance will be greatly improved. Its technology and difficulty are far lower than the current DMD manufacturing level, only the level of the 1970s!) It is not difficult to reach this speed!

When the white light spectrum in [Figure 2] is irradiated on the DMD micromirror array, light of different frequencies will fall on different areas, and the curve in the figure represents the spectrum distributed on the DMD palette (1) ( Strip spectrum) wavelength distribution and relative intensity (the range of light waves in the visible region is from 4000 angstroms to 7600 angstroms), control the micromirrors on each spectral region on the DMD palette (1) to turn and maintain the proportional relationship, you can Controls the brightness of the color after the output light from the light path is mixed. (3) is the lead-out electrode cable of DMD palette (1), and it controls the turnover of each micromirror.

As shown in [Figure 3]: the comb-shaped light guide collimator is composed of multiple optical fibers, the sides of each fiber are in close contact with each other and the areas (10) and (11) of the two end faces of each fiber are one larger and the other is larger. Small, one end of the larger cross-sectional area of the fiber is arranged on one side (12), and the other end (13) of the smaller cross-sectional area is arranged on the other side, and the formed optical fiber collimator is a pillar, and the two pillars The area of the bottom surface is not equal, and the two end surfaces of each optical fiber all constitute a part of the two bottom surfaces (12), (13) of the column, and the end surface (10) with a larger cross-sectional area is located at the bottom surface of the larger area of the column ( 12), the end surface (11) with a larger cross-sectional area is located on the bottom surface (13) with a larger area of the platform column, and the side surface (15) of the platform column is a part of the conical surface, that is, a positive conical surface or a non-positive conical surface. The side of each optical fiber is covered with one or more dielectric layers (16), and the refractive index of the material of the dielectric layer (16) closest to the surface of the optical fiber is greater than that of the optical fiber material. The optical fiber, layer and adhesive (or hot-melt material) are glass-like inorganic materials or polymer-like organic materials.

Its working principle is: when the light beam (20) with a larger scattering angle enters from the end of the table (13) with a smaller area of the optical fiber collimator (column), the light will continuously shine on the side of each optical fiber filament. It is obvious that every time the light is reflected, the angle between it and the central axis of the optical fiber will decrease. The two ends of the collimator are basically parallel to the center line (22), so that when the other bottom surface (13) exits, the collimation will be improved.

The two bottom surfaces (12) and (13) of the pillar are circular, polygonal, curved polygon and other shapes, and the shapes of the two bottom surfaces are similar or non-similar. The cross-sectional shape of the optical fiber filament in the optical fiber collimator can be circular, hexagonal with curved sides, regular hexagonal, etc.

Under the current process conditions (hot-melt stretching process with a fiber diameter of 10 ^-2 mm), the collimation level can reach 10 ^-2 degrees.

Claims (10)

1. An incoherent light full-spectrum domain modulation method, which consists of a light source, an optical fiber collimator, a diffraction grating or a prism, and a digital micromirror device DMD palette. Its working principle is: the golden light emitted by the light source is white light It is collimated by the fiber collimator, and then projected onto the diffraction grating or prism after being bundled; the light beam is expanded into a spectrum by the diffraction grating or prism, and the spectrum is projected onto the DMD palette. When the video control signal is used to drive the DMD When using the color palette, each micromirror on the DMD will be controlled whether to flip, so that the amount of light of different wavelengths entering the optical channel will be controlled, and the light effectively reflected by each micromirror on the DMD palette will be superimposed Gathering at one point will represent the brightness and chromaticity of the video signal; its characteristic is that the modulation method uses a diffraction grating or a prism to expand the mixed light, that is, white light with a certain color temperature, into a spectrum or red, blue, The green three primary colors converge on the same DMD chip at the same time; use fiber collimator to collimate the light beam; use the distributed duty cycle control method to drive each micro-mirror on the DMD palette; combine all the DMD micro-mirrors Effective reflected light bundle can get a small light beam that directly expresses the chromaticity and brightness of the video signal. 2. The incoherent optical full-spectrum domain modulation method according to claim 1, wherein the diffraction grating is a reflection grating or a transmission grating, and the grating stripes are straight or curved. 3. The incoherent light full spectrum domain modulation method as claimed in claim 2, characterized in that the optical fiber collimator is composed of a bundle of optical fibers with different diameters at both ends, and the diameter of each optical fiber is larger One end is bundled together, and the other end with a smaller diameter is also bundled together. The diameter of the formed optical fiber bundle is larger at one end and smaller at the other end. The surface of the optical fiber filament is covered with a medium with a lower refractive index than the inner layer of optical fiber filament. 4. The non-coherent light full-spectrum domain modulation method as claimed in claim 3, characterized in that the distributed duty cycle control method means: the spectrum irradiated on the DMD is a panchromatic spectrum, and the light of different frequencies will It is irradiated to different areas on the DMD, and the flip ratio relationship of the micromirrors on the different areas illuminated by different colors of light on the DMD can be controlled to control the color and brightness of the mixed output light from the optical path; the flip ratio relationship is A two-dimensional function whose argument is the plane position coordinates of the DMD micromirror. 5. The method according to claim 4, characterized in that the spectrum is formed in a continuous spectrum through gratings and prisms; or through three independent red, blue, and green light sources simultaneously irradiating different areas of the DMD wafer to form color bars. 6. A video projection optical machine using incoherent light full-spectrum domain modulation method, its optical path system is composed of light source, fiber collimator, diffraction grating or prism, digital micromirror device DMD palette, cluster lens group, optical Diaphragm, mechanical scanning system, projection objective lens, DMD drive circuit; its working process is: the white light emitted by the light source is collimated by the fiber collimator and then bundled, and the stray light is filtered by the diaphragm, and then projected to the diffraction On the grating or prism, it is expanded into a full-color spectrum, and the spectrum is projected onto the DMD palette, and after the brightness and tone control signals are sent to the control circuit of the DMD palette, each of the DMD palettes The turning and holding state of the micromirror will be controlled, the proportional relationship of flipping in different areas will be controlled, and the brightness and tone of the reflected light that enters the effective optical channel through the DMD palette will be modulated to obtain a consistent image with the video signal. Brightness and chromaticity; After being collimated and beamed, the mechanical scanning system completes the scanning and then the projection objective lens is focused on the focal plane; its characteristic is that a diffraction grating or prism is used in the optical machine to make the mixed light band The white light with a certain color temperature is expanded into a spectrum; the optical fiber collimator is used to collimate the beam; the distributed duty cycle control method is used to drive each micro-mirror on the DMD palette, control its flip, and reflect the DMD palette The reflected light entering the effective optical path channel is collimated by the fiber collimator again, scanned by the mechanical scanning system, and then focused on the focal plane by the projection objective lens. 7. The video projector according to claim 6, characterized in that the diffraction grating is a reflection grating or a transmission grating, and the stripes of the grating are straight or curved. 8. The video projection optical machine as claimed in claim 6, characterized in that the optical fiber collimator is composed of a bundle of optical fibers with different diameters at both ends, and the ends with larger diameters of each optical fiber are bundled together , the other ends with smaller diameters are also bundled together, the diameter of the formed optical fiber bundle is larger at one end and smaller at the other end, and the surface of the optical fiber is covered with a medium with a lower refractive index than the inner layer of optical fiber. 9. The video projector as claimed in claim 6, characterized in that the distributed duty cycle control method means that the spectrum irradiated on the DMD is a panchromatic spectrum, and light of different frequencies will be irradiated on the DMD In different areas of the DMD, the color and brightness of the mixed output light of the optical path can be controlled by controlling the flip ratio of the micromirrors on different areas illuminated by different colors of light on the DMD; the flip ratio is a two-dimensional function , the independent variable of the function is the plane position coordinates of the DMD micromirror. 10. The optical projector for video projection according to claim 9, characterized in that the spectrum is formed in a continuous spectrum through a grating and a prism; or through three independent red, blue, and green light sources simultaneously irradiating different areas of the DMD chip The color bars formed above.

Images