CN210323739U - Two-piece LCD projector based on half field sequential display mode - Google Patents

Abstract

The utility model provides a two-piece LCD projector based on a half-field sequential display mode, which comprises a first and a second black-white transmission type LCD light valve module; the first LCD light valve module alternately displays red and blue field images of an input video signal and is alternately illuminated by a red LED light source and a blue LED light source; the alternate lighting and extinguishing periods of the red LED light source and the blue LED light source are synchronous with the alternate periods of the red field and the blue field of the LCD light valve; the second LCD light valve module is used for displaying a green field image of the input video signal and is illuminated by a green light source in a constant brightness mode; the light rays passing through the first and the second LCD light valve modules are combined by the light combining device, and finally the images displayed by the two LCD light valve modules are projected and displayed on the curtain by the field lens and the projection lens. The utility model has the characteristics of the cost is lower, simple structure, easy preparation, and energy conversion efficiency is higher, watches tired sense lighter, can export high luminance etc.

Description

Two-piece LCD projector based on half field sequential display mode

Technical Field

The utility model relates to a LCD projector.

Background

For a long time, projectors are generally classified based on the characteristics of a Light valve, which is one of the most core devices of the projectors, such as a DLP (Digital Light Processing) projector, an LCD (Liquid Crystal Display) projector, an LCOS (Liquid Crystal on Silicon) projector, and the like.

The conventional LCD projector is referred to as having: its light valve is a feature of both LCD technology (to distinguish DLP) and transmissive (to distinguish LCOS). The LCD projector generally has two principles and structural forms of a single LCD projector and a 3LCD projector, the common single LCD projector uses a full-Color LCD light valve to reproduce a spatial Color image under the irradiation of a white light source or an equivalent white light source, the common 3LCD projector uses 3 monochromatic (black and white) LCD light valves, namely, the LCD light valves are not provided with CF (Color Filter, Color Filter, Color film and the like) devices used by the single LCD projector light valve, red, green and blue primary Color lights illuminate three paths of LCD light valves, each path of LCD light valves displays a pure primary Color field image of an input video signal, and finally, the three primary Color images generated by the 3 light valves are superposed, thereby generating a spatial Color image as the single LCD projector using the full-Color LCD light valves.

The single LCD projector has the advantages of low manufacturing cost, simple manufacture, stable image without flicker, and different brightness from more than ten lumens to three-four hundred lumens, and has larger competitiveness in the consumer digital market because the price of the single LCD projector is extremely low; the 3LCD projector has rich colors, good picture quality, high brightness, stable image and no flicker, is complex to manufacture, has high access threshold, has high product cost, has the brightness which is different from 800-8000 lumens, and is the main force of the traditional commercial and teaching projector markets.

DLP projectors are time-based pure field sequential displays (except for 3-chip DLP projectors), and display field images such as R, G, B Of an input video signal alternately with time, and synthesize color images in the human brain by the Persistence Of Vision (Persistence Of Vision). DLP projector is efficient, and the picture quality is better. However, since the core devices are exclusively supplied by TI (texas instruments) company, and the manufacturing is complicated, the access threshold is high, the cost is high, and the defect of poor color reduction of the LED light source is improved. Because the DLP projector displays R, G, B field images in a pure field sequential manner, the feeling of viewing fatigue caused by image flicker is always an important factor affecting the user experience.

In the projection product market in recent years, the 3LCD projector, the single LCD projector and the DLP projector are mainly used.

The greatest disadvantage of single LCD projectors is that the "energy conversion efficiency" η is too low, usually defined for η as η ═ output brightness (Lm)/input electrical power (w)/100(Lm/w) × 100% >, where the LED light efficiency is typically 100 lumens per watt for high power LED modules, thus η is typically only 2% to 3.5%. whereas 3LCD and DLP projectors η using UHP bulbs, LEDs, lasers, etc. are typically easy to reach 10% or even more than 25%.

The most important factor of the single LCD projector η is that the efficiency of the light valve module is too low, generally only 4% -7%, which is determined by the aperture ratio of the polarizer, the color Film, the TFT (thin Film transistor) and so on, the polarizer efficiency is about 35% -40%, the CF efficiency is about 5% -21%, the TFT aperture ratio is about 50% -70%, but the dark areas of the CF and TFT aperture ratios (i.e. black frame and so on structures) have a certain overlap portion, so the data can not be directly multiplied to obtain the total efficiency of the LCD module.

When the CF is taken off to display a color image, either 3LCD light valves like a 3LCD projector are needed, or three primary color field sequential display is needed with enough fast response speed like a DLP projector. Obviously, the two modes are not easy to implement, the 3LCD technology has high cost, the manufacture is difficult, and the industrial chain has more restrictions; in the pure field sequential display, the current LCD light valve based on amorphous silicon and low-temperature polysilicon technologies combines with actual demand indexes such as resolution, contrast, etc., and is to be put into practical use and commercialized, and the refresh rate thereof is not enough at all: the first is that the minimum refresh rate requirement of a single-chip pure field sequential display mode of 150Hz is not possible to be achieved basically, and the second is that even though the minimum refresh rate requirement of 480Hz refresh rate (tested by using a special high-temperature polycrystalline silicon LCD light valve), images can generate serious tailing and display disorder, bad phenomena such as tailing (namely, the light source is turned off in the tailing and display disorder time of the LCD light valve) and the like are avoided by controlling the starting and stopping of the light source, so that the duty ratio of the light source is determined to be reduced remarkably, the output brightness of the light source is reduced remarkably inevitably, the initial purpose of taking away the CF, expecting to greatly improve the brightness, and improving the energy utilization rate is lost.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model lies in, to prior art's above-mentioned defect, provide a two formula LCD projectors and projection method based on half field order mode, realize lower manufacturing threshold, higher price/performance ratio, higher energy conversion efficiency, the tired sense of lighter watching, and can realize high luminance output.

The utility model provides a two formula LCD projectors based on half field order display mode, including red LED light source, green LED light source, blue LED light source, beam condensing unit, close light device, light integral device, overlap lens, holophote, focusing lens, first and second two black and white transmission-type LCD light valve module, field lens and projecting lens; the first LCD light valve module alternately displays red field images and blue field images of input video signals and is illuminated by a red LED light source and a blue LED light source alternately in a field sequence; the alternate lighting and extinguishing periods of the red LED light source and the blue LED light source are synchronous with the alternate periods of the red field and the blue field of the LCD light valve; the second LCD light valve module is used for displaying a green field image of the input video signal and is illuminated by a green light source in a constant brightness mode; the light rays passing through the first and second two LCD light valve modules are combined by the light combining device, and finally the images displayed by the two LCD light valve modules are projected and displayed on the curtain by the field lens and the projection lens. The utility model has the characteristics of low cost, simple structure, easy manufacturing, energy conversion efficiency is higher, watches tired sense lighter, and can export high luminance etc.

In some embodiments, the lighting starting point of the red LED light source and the lighting starting point of the blue LED light source lag behind the starting point of the corresponding red and blue field display of the LCD light valve for field sequential display for a certain time; and the extinguishing points of the red LED light source and the blue LED light source are ahead of the stop points of the corresponding red and blue field display of the LCD light valve of the field sequential display for a certain time.

In some embodiments, the first and second LCD light valve modules have the same size, the same total number of pixel particles, a refresh rate of 80Hz or more, and no CF device on the modules.

In some embodiments, the red, green, and blue combining device is selected from a dichroic glass plate, a PBS film, or a PBS prism.

In some embodiments, the red, green and blue light combining device is a dichroic glass plate, the wavelength of the splitting point is selected to be less than or equal to 475nm and greater than or equal to 595nm for light transmission, and the wavelength of the light is selected to be 475nm to 595nm for light reflection.

The utility model has the advantages that compared with the existing single LCD projector, the energy conversion efficiency is obviously improved, but the characteristics of simple structure and low cost of the single LCD projector are kept; compared with the existing 3LCD projector, the projector has the characteristics of easy manufacture and low cost, but has high energy conversion efficiency of the 3LCD projector; compared with the existing DLP projector, the DLP projector has higher energy conversion efficiency, and because the DLP projector adopts half-field sequential display (only red and blue field images are alternated, and a green field is constant in brightness and does not participate in alternation), the fatigue feeling of watching is much lighter than that of the DLP projector in which red, green and blue are involved in alternation; because the RGB three-color light that jets out LCD light valve can carry on the light with the cheaper way, the light valve size is to the little influence of cost and performance of this red green blue light-combining device, so the size of this two pieces of LCD light valve module can be bigger, for example reach more than 4-5 inches, so light valve Etend (optical expansion) will be bigger too, so allow the light source of the larger light-emitting area to illuminate, because the output luminous flux of LED light source, and the light-emitting area is in direct proportion basically, so the projector can output the very high luminance.

Drawings

The invention will be further explained with reference to the drawings and examples, wherein:

fig. 1 illustrates a schematic structure of a two-chip LCD projector based on a half field sequential display mode according to the present invention.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 illustrates a schematic structure of a two-chip LCD projector based on a half field sequential display mode according to the present invention. The utility model discloses a two formula LCD projectors 100 includes: the light source comprises a red LED light source 1, a first light condensing device 2, a blue LED light source 3, a second light condensing device 4, a red-blue light combining device 5, a red-blue channel light integrating device 6, a first overlapping lens 7, a total reflecting mirror 8, a first focusing lens 9, a first LCD light valve module 10, a green LED light source 11, a third light condensing device 12, a green channel light integrating device 13, a second overlapping lens 14, a second focusing lens 15, a second LCD light valve module 16, a red-green-blue light combining device 17, a field lens 18 and a projection lens 19.

The utility model discloses a two formula LCD projectors basic work principle is: LED light sources 1 and 3 of a red channel and a blue channel are condensed by respective condensing devices 2 and 4, then are combined by a red-blue light combining device 5, and irradiate on a light integrating device 6, and a first LCD light valve module 10 is uniformly illuminated by the light integrating device 6, a first overlapping lens 7, a total reflecting mirror 8 and a first focusing lens 9, wherein the first LCD light valve module 10 alternately displays red field images and blue field images of input video signals and is alternately illuminated by the red LED light source 1 and the blue LED light source 3; the alternating periods of the red LED light source 1 and the blue LED light source 3 are synchronous with the alternating field sequence of the red field image and the blue field image of the first LCD light valve module 10; similarly, the second LCD light valve module 16 displays the green field image of the input video signal, and is illuminated by the green LED light source 11; the light passing through the first and second LCD light valve modules 10 and 16 is combined by the red, green and blue light combining device 17, and the images displayed by the first and second LCD light valve modules 10 and 16 are projected on the screen by the field lens 18 and the projection lens 19. The field sequential red and blue field images generated by the first LCD light valve module 10 are superimposed with the green field images generated by the second LCD light valve module 16 by using the visual residual effect of human eyes, so that the RGB colors are finally overlapped in time and space to generate a full color image in the human brain.

The field sequential display mode realizes full-color image perception of human brain and is realized based on the residual visual effect of human eyes. However, the present invention is different from the general full-color field sequential display technology (such as the monolithic DLP projector, some special monolithic field sequential LCD projectors, monolithic field sequential LCOS projector, etc.) based on pure time completely, and is characterized in that: the first is that the utility model is a half field sequential display, namely, except the interval of idle duty ratio of red and blue LED light sources, there are two primary color outputs (R and G, G and B) at any time, instead of a pure field sequential display mode, there is only one primary color field output at any time; secondly, one primary color is constant in brightness, does not participate in field sequence alternation, and is displayed in pure space; thirdly, two fields are used for displaying field sequence based on time, and are pure time display, so the utility model is a time and space composite display; fourthly, outputting a green field image which has the brightness occupying the absolute main component and has the highest human eye perception degree (near 555 nm) to the projector, and displaying the green field image by the green light source 11 and the second LCD light valve 16 in a constant brightness mode without flicker, so that the image flicker generated by the first LCD light valve 10 due to the alternation of red and blue fields greatly reduces the visual fatigue degree of human eyes when watching (the image flicker is sensitive to light rays near 450nm and 630nm and far has no light rays near 555 nm); and fifthly, the image of only two primary colors participates in field sequence alternation, compared with the field sequence alternation in which all three primary colors participate, the flicker feeling is exponentially slowed down, and the requirement on the refresh rate of the light valve is reduced by times.

Under the condition of ensuring certain white balance of the projection picture, R, G, B primary color LED light sources are used for the light sources 1, 3 and 11, wherein the green LED light source 11 is used for illuminating the second LCD light valve module 16 in a constant brightness mode; the red LED light source 1 and the blue LED light source 3 are alternately lightened according to a certain duty ratio and a certain time sequence, because the field sequence of the first LCD light valve module 10 is synchronous, the lightening interval between the two light sources is very critical, the lightening interval is very critical, the reasonable duty ratio is required, and the image trailing is avoided.

The light condensing devices 2, 4, 12 generally adopt a lens group mode, the solid angle of the output light beam of the light condensing device is determined according to the design characteristics of the light integrating devices 6, 13, the light integrating device can obtain higher efficiency within 12 degrees of the solid angle of the output light beam of the light condensing device, but the value of the solid angle of the light beam is preferably less than or equal to 7 degrees in consideration of the overall efficiency, color uniformity and other factors, which can increase the volume of the whole optical system from the light source to the lens.

The red and blue light combination device 5 adopts a dichroic glass plate manufactured by vacuum coating, the wavelength division is almost not required, and the device can be used at any point within 500-560 nm.

The light integration devices 6 and 13 are preferably made of a relatively inexpensive resin compound, and an integration rod (solid or hollow) may be used, but regardless of the compound lens or the integration rod, a PCS (polarization conversion System) device may be added to improve the light utilization rate, and the improvement of the light utilization rate after the PCS device is added is determined by many factors, such as the size of the solid angle of the light beam, the limitation of the lens Fno (f-number), the efficiency of the PCS itself, and the like.

The superimposing lenses 7 and 14 superimpose the light beams generated by the sub-light source images outputted from the light integration devices 6 and 13.

The focusing lenses 9 and 15 focus the sub-light source images generated by the light integration devices 6 and 13 on the windows of the first and second LCD light valve upper modules 10 and 16 with high efficiency and low distortion, so as to realize uniform illumination of the first and second LCD light valve modules 10 and 16.

First and two LCD light valve modules 10, 16 of second are two black and white not have the LCD screen of the same size and the pixel quantity of CF device promptly, if the utility model discloses the application is as the original intention with obtaining higher output luminance, so the incidence of these two LCD light valve modules 10 and 16, the polaroid of emergent side (generally be the absorption formula), all should not directly laminate in these two LCD light valve modules 10, 16 income, on the emergent glass face, need separate, laminate and respectively place in LCD light valve module 10 on solitary glass substrate, 16's both sides to need measures such as efficient forced air cooling to dispel the heat. In front of the polarizers (close to the direction of the LED light source) on the incident side of the two LCD light valve modules 10 and 16, a reflective polarizer is required to be installed regardless of whether the lighting system is equipped with a PCS device or not, so as to protect the safety of the absorptive polarizer to the maximum extent.

The red, green and blue light combining device 17 is preferably implemented by selecting devices with wavelength or vibration axis phase segmentation characteristics such as dichroic glass plates and the like, and setting the light solid angle to be a single edge within 45 +/-7 degrees. The red, green and blue light combining mirror 17 selects the light transmission of less than or equal to 475nm, the light transmission of more than or equal to 595nm and the light reflection of 465-595 nm, but such wavelength division points are not completely selected, and requirements such as the characteristics of a light source, color coordinates, color gamut, efficiency and the like are determined according to specific conditions.

The red, green, and blue light combining device 17 may also be a PBS (Polarization Beam Splitter) film attached to a green plate or white plate glass to achieve light combining, but has requirements on the Polarization phase (axis) of the polarized light emitted from the first and second LCD light valve modules 10 and 16, that is, the polarized light emitted from the two LCD light valve modules 10 and 16 is required to be orthogonal; the light can also be combined by means of a PBS prism and the like, and the PBS prism has better durability and thermal stability especially in the occasions with extremely high brightness output, such as the output of a projector of more than 6000 lumens.

The choice of the specific type of rgb light combining device 17 is determined by the cost performance, i.e., the cost, the output brightness level, the image quality requirement, and some specific engineering factors of the projector.

The field lens 18 is a part of the projection lens in the optical system, but when the size of the LCD light valve module is large (e.g. 3-5 inches), the field lens 18 and the projection lens 19 are not easy to be manufactured together due to the cost relationship, and the field lens 18 usually uses a cheap plastic fresnel lens to obtain a simpler lens design than a glass lens.

The projection lens 19 is a single LCD projector lens with the same light valve window and resolution, the design of the utility model does not cause additional influence on the Fno of the projection lens 19 when no PCS device is arranged on the lighting system; if the PCS device needs to be added, the evaluation of the balance between the reduction of the light emitting area of the LED light source and the addition of the PCS device is carried out by specifically judging whether the Fno of the lens is allowed or not and reducing the Fno value.

It should be understood that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same, and those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some technical features; and that such modifications and substitutions are intended to be included within the scope of the appended claims.

Claims (5)

1. A two-piece LCD projector based on a half field sequence display mode comprises a red LED light source (1), a first light condensing device (2), a blue LED light source (3), a second light condensing device (4), a red and blue light combining device (5), a red and blue channel light integrating device (6), a first overlapping lens (7), a total reflector (8), a first focusing lens (9), a first LCD light valve module (10), a green LED light source (11), a third light condensing device (12), a green channel light integrating device (13), a second overlapping lens (14), a second focusing lens (15), a second LCD light valve module (16), a red, green and blue light combining device (17), a field lens (18) and a projection lens (19); the method is characterized in that: the first LCD light valve module (10) alternately displays red and blue field images of an input video signal, and the red LED light source (1) and the blue LED light source (3) alternately illuminate; the alternating periods of the red LED light source (1) and the blue LED light source (3) are synchronous with the alternating field sequence of the red field image and the blue field image of the first LCD light valve module (10); the second LCD light valve module (16) displays the green field image of the input video signal and is illuminated by the green LED light source (11) in a constant brightness mode; the light passing through the first LCD light valve module (10) and the second LCD light valve module (16) is combined by the red, green and blue light combining device (17), and the image displayed by the first LCD light valve module (10) and the second LCD light valve module (16) is projected and displayed on a curtain by the field lens (18) and the projection lens (19).

2. The two-chip LCD projector according to claim 1, wherein: the alternative lighting starting point of the red LED light source (1) and the blue LED light source (3) lags behind the starting point of the corresponding red and blue field display of the first LCD light valve module (10) for a certain time; the alternate extinguishing points of the red LED light source (1) and the blue LED light source (3) are ahead of the stop points of the corresponding red and blue fields of the first LCD light valve module (10) for a certain time.

3. The two-chip LCD projector according to claim 1, wherein: the first LCD light valve module (10) and the second LCD light valve module (16) have the same size, the total number of pixels is the same, the refresh rate is not less than 80Hz, and no CF device is arranged on the modules.

4. The two-chip LCD projector according to claim 1, wherein: the red, green and blue light-combining device (17) selects a dichroic glass plate, a PBS film or a PBS prism.

5. The two-chip LCD projector according to claim 4, wherein: the red, green and blue light combining device (17) selects a dichroic glass plate, the wavelength of the division point of the dichroic glass plate is selected to be less than or equal to 475nm and greater than or equal to 595nm for transmission, and the wavelength of the dichroic glass plate is selected to be 475nm to 595nm for reflection.

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