Polarization converter and polarized light source and relevant projecting system
Technical field
The present invention relates to the light polarization conversion method and the device of light source.Said light source is mainly used in projection display system.
Background technology
Typical projection display system comprises light-source system, and this light-source system comprises some monochromatic sources, such as but not limited to red light source, green light source and blue-light source, produces ruddiness (R), green glow (G) and blue light (B) light beam respectively.
The existing brightness of light-source system in order to reduce cost and to improve the light source emergent light can adopt the light conversion device of excitation source and band optical wavelength conversion material to produce various homogeneous beams.Said optical wavelength conversion material comprises fluorescent powder, dyestuff or nano luminescent material.Said light conversion device is an example with the colour wheel device; Usually come one or more fluorescent powder of segment bearing with a colour wheel; Utilize the emergent light of excitation source to shine the said colour wheel that is rotating, with the stimulated luminescence of timesharing acquisition with the corresponding color of fluorescent powder of each segmentation.For example tricolor projection's display system normally produces based on blue-ray LED and shows required red, green, blue monochromatic light.
When the crowd knew the fluorescent powder stimulated luminescence, light emission direction had isotropy, the even outgoing of stimulated luminescence all directions just.Therefore general light source comprises that the light source emergent light of UHP bulb, led light source and above-mentioned prior art is nonpolarized light.
And in LCD projecting system or LCoS (Liquid Crystal on Silicon) optical projection system; The linearly polarized light that can only rely on predetermined direction because of display chip liquid crystal or LCoS chip shows, makes only about 50% can be utilized in the light output energy of general light source.Such display system often is necessary light output the carrying out conversion of nonpolarized light to polarized light to general light source in order to solve the low problem of bringing thus of source efficiency.The general employing of existing polarization conversion technique working method as shown in Figure 1:
Wherein, the effect of polarization spectro sheet 1 is with non-polarized incident light 41, and the light of just general light source output is divided into two bundle polarized lights with transmission and reflection way respectively: P light 42 and S light 43.The polarization direction of this two-beam is vertical each other.Utilize catoptron 2 with past 1/2nd wave plates 3 of S light 43 reflections again, logical this 1/2nd wave plate 3 revolves the polarisation of light direction to turn 90 degrees and obtains P light 44.Like this, generally the nonpolarized light of light source output is through becoming the polarized light that comprises P light 42 and P light 44 after changing.
The weak point of above-mentioned prior art is: the area of light beam will be enlarged in the polarization conversion process.Though general light source through said polarization conversion after, available in theory polarized light energy has improved 2 times, optical extend (Etendue) is along with the expansion of beam area has also enlarged 2 times.Therefore concerning optical projection system, light-source brightness (luminous flux in the Brightness, unit angular unit area) is not improved.In fact, consider the optical loss in the polarization conversion, light-source brightness is lowered on the contrary.Because the UHP bulb has lower optical extend, 2 times of expansions of the optical extend that perhaps above-mentioned polarization conversion caused are not obvious with corresponding brightness reduction influence; But, when optical projection system is used this light source more and more widely, will sacrifice projection brightness undoubtedly for led light source with big optical extend.
Summary of the invention
The technical matters that the present invention will solve is the weak point to above-mentioned prior art; And a kind of polarization converter and polarized light source and relevant projecting system are proposed; Directly the high brightness emergent light with light source converts polarized light to, can be used for improving the light source service efficiency of projection application system.
For solving the problems of the technologies described above; Of the present inventionly be contemplated that basically: with the colour wheel of band optical wavelength conversion material is power and the brightness that the existing light source light conversion equipment of example is convenient to improve light source; And the polarization spectro sheet can only be made into according to the one dimension direction and carries out beam split in the prior art; Rotate with colour wheel as if this light splitting piece directly is placed on the colour wheel, also will rotate in time, can't obtain stable emerging ray polarized light because of the linearly polarized light direction of outgoing; Consideration is carried out structure of modification to said light conversion device; An if fixing reflective polarizing light splitting piece that does not rotate on the emergent light direction with colour wheel; The light that is then reflected by this polarization spectro sheet can pass through the scattering of fluorescent powder and eliminate polarization state, thereby has nearly 50% to be converted into polarized light output again during once more through the polarization spectro sheet; Like this, the high-power and high-luminance polarization state light energy of the final outgoing of light source will be able to strengthen, and the outgoing facula area can increase hardly.
The present invention provides a kind of polarization converter, and wherein, this polarization converter comprises stationary installation (107); And the moving surface (104) that has the state of rotatablely moving with respect to said stationary installation; This moving surface (104) carries one or more optical wavelength conversion materials (103), and this optical wavelength conversion material (103) is used to absorb exciting light to produce stimulated luminescence; This polarization converter also comprises the reflective polarizing light-dividing device (101) that is fixed on the said stationary installation (107); There is not polarization conversion device between this light splitting device (101) and the said optical wavelength conversion material (103); This reflective polarizing light-dividing device (101) is used for the part light of transmission from the stimulated luminescence of said optical wavelength conversion material, and will be from the said optical wavelength conversion material of all the other light reflected backs of the stimulated luminescence of said optical wavelength conversion material.
The present invention also provides a kind of polarized light source, and wherein, this polarized light source comprises light emitting source and above-mentioned polarization converter, and this light emitting source is used to provide said exciting light.
The present invention also provides a kind of optical projection system with light source, and wherein, this optical projection system comprises liquid crystal or LCoS and above-mentioned polarized light source.
Adopt above-mentioned each technical scheme, owing on moving surface, use optical wavelength conversion material, can be so that the heat dissipation problem of solution optical wavelength conversion material have prolonged its serviceable life; When said light emitting source adopts solid state light emitter, compare, have the life-span height, be convenient to control and the advantage of environmental protection with the UHP bulb; Through controlling the polarization spectro sheet to moving surface; Colour wheel for example, distance control the projected spot size, and dwindle the brightness that as far as possible strengthens the outgoing polarized light through this distance; Significantly improve the ray machine efficient of optical projection system, and had the advantage that cost is low, be convenient to implement.
Description of drawings
Fig. 1 is the principle of work synoptic diagram of existing polarization conversion;
Fig. 2 is that the present invention is one of the polarization converter structure of example synoptic diagram with the colour wheel;
Fig. 3 is that the present invention is two synoptic diagram of the polarization converter structure of example with the colour wheel;
Fig. 4 is that distance influences synoptic diagram to spot size between colour wheel of the present invention and the polarized luminescence sheet;
Fig. 5 is that the present invention is three synoptic diagram of the polarization converter structure of example with the rotary drum;
Fig. 6 illustrated polarization converter embodiment of the present invention four in displacement disc;
Wherein, each Reference numeral is: 1--polarization spectro sheet, 2--catoptron, 3--1/2nd wave plates, 41--non-polarized incident light, 42,44--polarization P light, 43--polarization S light; The 10--colour wheel, 101--polarization spectro sheet, 102--optical filter, 103--fluorescent powder/optical wavelength conversion material, 104--colour wheel basal disc, 105--light transmission piece, the rotating shaft of 106--colour wheel, 107--colour wheel fixed cover; The 108--adjusting knob.
Embodiment
Below, further set forth the present invention in conjunction with the most preferred embodiment shown in the accompanying drawing.
Of background technology, existing light source generally is a polarization conversion of accomplishing the light source emergent light with polarization spectro sheet and 1/2nd wave plates.For this reason, the polarization converting method of the present invention's proposition comprises the following steps:
Polarization converter is set, the moving surface that carries one or more optical wavelength conversion materials is kept in motion; Said light conversion device or comprise like Fig. 2 or colour wheel shown in Figure 3, or comprise rotary drum as shown in Figure 5 or displacement disc as shown in Figure 6 (mode of motion or direction are with arrow signal among the figure) as the embodiment of the invention proposed; Said optical wavelength conversion material comprises fluorescent powder, dyestuff or nano luminescent material;
Guiding comes the directed projection of the light of self-emitting light source toward this polarization converter, and this light directly drops on projected spot on the said moving surface less than said moving surface, makes the different local period property of said moving surface get into the projection scope of this light by turns;
Guiding is the emergent light of said light source from the stimulated luminescence of said optical wavelength conversion material;
Wherein, Emergent light direction at said light source; Near said moving surface one static reflective polarizing light-dividing device is set; Make from the stimulated luminescence part transmission of said optical wavelength conversion material and pass the polarization emergent light that this light splitting device provides said light source, a part is reflected back toward said optical wavelength conversion material.Like this, the polarization state that the light of the said optical wavelength conversion material of reflected back had can be passed through the scattering of fluorescent powder and is eliminated, and this light has 50% and is able to utilize when passing through the polarization spectro sheet once more, strengthened the polarization state light energy of outgoing.Move because this light splitting device needn't be attached moving surface, make the daylighting area make light splitting device become possibility less than the area of said moving surface.From saving cost and simplification device structure angle, said light splitting device preferably adopts the reflective polarizing light splitting piece, and the area that makes the area of this polarization spectro sheet be slightly larger than said projected spot is advisable.Among following each embodiment, do not have special instruction, said light splitting device is a most preferred embodiment with said polarization spectro sheet all.
To be example with the colour wheel illustrated the structure of polarization converter of the present invention with the form of cross-sectional schematic to Fig. 2.This polarization converter comprises stationary installation 107 and colour wheel 10.Said colour wheel 10 comprises the moving surface 104 that has motion state with respect to stationary installation 107, and this moving surface uses light transmissive material, and carries one or more optical wavelength conversion materials 103.Fixed cover or housing that said stationary installation 107 can be a colour wheel, colour wheel rotating shaft 106 is embedded on this stationary installation 107 through axle sleeve rotationally.Said optical wavelength conversion material 103 can be with the mode sticker that mixes with jelly on the printing opacity basal disc that constitutes said moving surface 104.Perhaps shown in dotted line, this optical wavelength conversion material 103 is to be clamped and fixed between a light transmission piece 105 (for example glass sheet) cheaply and the said printing opacity basal disc.In order to increase the penetration power of light, the one or both sides plating anti-reflection film (AR Coating) on said light transmission piece 105 or moving surface printing opacity basal disc 104 at low cost; Because of it is existing mature technology, does not give unnecessary details or illustrate at this.
Among this embodiment, said polarization converter also comprises the polarization spectro sheet 101 that is fixed on the said stationary installation 107, the said moving surface 104 of this polarization spectro sheet 101 next-door neighbours, and area is less than the area of said moving surface.In prior art, the projected spot of coming self-emitting light source often area is merely 0.2%~20% of said moving surface area, and the area of said polarization spectro sheet can be set at 0.2%~20% of said moving surface area according to this.
The inventive method such as this embodiment signal, the opposite side that can also be included in the said dorsad polarization spectro sheet 101 of said moving surface 104 is provided with the step of a static optical filter 102.This optical filter 102 is used for reflecting said stimulated luminescence and makes the transmittance of self-emitting light source to pass this optical filter.Therefore, this optical filter 102 also is fixed on the said stationary installation 107, and the distance distance between said moving surface is more little good more.In order to save cost as far as possible, the shape of this optical filter 102 or area are set at the shape or the area of said polarization spectro sheet 101 roughly the same.
Fig. 2 has illustrated that said polarization spectro sheet 101 or optical filter 102 are to be fixed on the said stationary installation 107 through clamping device.The method of clamping that said clamping device or clamping device adopt, or it is equal to the replacement means because prior art is not given unnecessary details at this.
Fig. 3 has illustrated that polarization converter structure of the present invention is the another embodiment of example with the colour wheel.In the present embodiment, said optical wavelength conversion material 103 can be to be entrained on the said moving surface 104 that uses light transmissive material.Such as but not limited to fluorescent powder is doped in the glass, be used as said moving surface 104 with a band fluorescent powder basal disc with suitable intensity.
Cost based on the more little then light conversion device of size of polarization spectro sheet 101 is economized more; When the light source that uses polarization converter of the present invention had very little said projected spot, polarization spectro sheet 101 or optical filter 102 needed accurately control to the distance of moving surface 104 (for example colour wheel).As shown in Figure 4, represent the distance between the colour wheel of optical element and top of below with d.If said optical element is an example with optical filter 102, then stimulated luminescence is through after the reflection of this optical filter 102, and the primary light spot size will be expanded B by A; If said optical element is the polarization spectro sheet, this polarization spectro sheet reflection exciting light and partial polarization attitude stimulated luminescence, then A and B represent the original size and the enlarged in size of projected spot respectively.Obviously, no matter be to polarization spectro sheet 101 or to optical filter 102, and big more apart from d between the said moving surface 104, B will be enlarged greatly more, and will be also big more to the output brightness influence of light source.Therefore said distance should be less than 20% of the circumscribed circle diameter of said projected spot, and is more little good more.
As shown in Figure 3, the fixed sturcture of said polarization spectro sheet 101 on said stationary installation 107 can also comprise fine tuning structure 108, is used for finely tuning said distance.Though do not illustrate in the present embodiment, can consider to add use optical filter 102 and fine tuning structure thereof yet.The test findings according to the present invention is 4 millimeters a square transmission hot spot for the length of side of coming self-emitting light source, and the distance between said polarization spectro sheet or optical filter and the said moving surface is being the best less than 0.6 millimeter.
With (but being not limited to) above-mentioned Fig. 2 or Fig. 3 is that the polarization converter of the present invention of example uses on the polarized light source that also includes light emitting source, and it is basic fair with unpolarized light source to help the light source cost is reduced to.Wherein, the polarization spectro sheet is close to said moving surface in light source emergent light one side.Said light emitting source can adopt solid state light emitter, such as but not limited to LED.
Through experimental verification, use the colour wheel of band yellow fluorescent powder, when light emitting source adopted blue-ray LED to produce white light output, when not carrying out polarization conversion, the polarized light output flow on any direction was merely 52% of light source emergent light total flux; After using polarization spectro sheet of the present invention, the polarized light output flow of this direction has increased by 20%.
Hold the above, polarization converter of the present invention can also replace colour wheel with rotary drum, and is as shown in Figure 5.Suppose to be divided at least two zones that comprise a and b, do not carry optical wavelength conversion material and have different light wavelength conversion characteristics through carrying different optical wavelength conversion materials or at least one zone like the hollow printing opacity drum movement face that arrow signal direction is rotated; Light emitting source is arranged on this drum; The place that then can press close to said drum movement face in the cylinder outside fixedly installs a polarization spectro sheet, and the area of this polarization spectro sheet can be significantly smaller than the loaded area of the area or the optical wavelength conversion material of said drum movement face.The moving surface of said hollow printing opacity cylinder also can not carry out area dividing, carries a kind of optical wavelength conversion material or mix to carry more than one optical wavelength conversion materials.Equally, when the displacement disc that moves along a straight line with Fig. 6 replaces rotary color wheel, also can spirit design corresponding light conversion device, compare with Fig. 2 or Fig. 3, but change the position and the manner of movable axis, not add diagram in addition at this according to the present invention.
Typical liquid crystal or LCoS optical projection system comprise that being used for timesharing provides the light source of the some homogeneous beams that comprise ruddiness, green glow and blue light.Said light source adopts light source of the present invention, has both simplified light source design undoubtedly, has improved the ray machine efficient of system again.