The eight groups ten ultralow projections of refraction-reflection type are than projection lens foundation structure
Technical field
The present invention relates to a kind of low projection than projection lens foundation structure, particularly a kind of eight groups ten ultralow projections of refraction-reflection type are than projection lens foundation structure.
Background technology
Distance between projector and screen is directly proportional to picture dimension, projector from screen more close to, the picture dimension projected is less, otherwise picture is then larger.In limited space, with the shortest distance realize maximum sized curtain screen picture be a new demand place in current and following practical application, be also the trend of projection field development.And the appearance of short out-of-focus projection camera lens makes everything become reality.Short out-of-focus projection camera lens has lower projection ratio, and so-called projection is than referring to the ratio of projector distance with projection image width, identical projector distance, and projection is than lower, and projected picture is larger.The projector being furnished with short out-of-focus projection camera lens only needs the projector distance of tens centimetres, just can realize larger projected picture.
The main flow implementation of existing short out-of-focus projection camera lens is refraction type based on geometric optical theory and refraction-reflection type.Wherein the lens optical system of refraction type is all made up of refractor, and refractor comprises spherical lens and non-spherical lens.The lens optical system of refraction-reflection type is made up of dioptric system and reflecting system, dioptric system comprises spherical lens and non-spherical lens, and reflecting system can be plane mirror, convex aspheric surface catoptron, concave surface non-spherical reflector, convex free-form surface mirror or recessed free-form surface mirror.By projection ratio, the projection of refraction type short out-of-focus projection camera lens whole realization than rank at 0.6: 1 grade, this digitized representation be the short burnt ability of short focus projector, the short burnt ability of the less explanation of ratio is stronger, for the realization of lower projection than rank, refraction-reflection type short out-of-focus projection camera lens is then needed, therefore also known as ultrashort out-of-focus projection camera lens.In a lot of actual engineering projection, short out-of-focus projection camera lens needs to have larger from axle offset ability, to meet from axial projection, therefore the design of short out-of-focus projection camera lens needs to consider the situation from axial projection, refraction-reflection type projection lens then needs to have larger from axle offset amount, realizes lower projection ratio.
Refraction-reflection type short out-of-focus projection camera lens can be divided into level crossing refraction-reflection type, aspheric mirror refraction-reflection type and free form surface mirror refraction-reflection type three kinds according to the type of internal system catoptron.For level crossing refraction-reflection type short out-of-focus projection camera lens, reach less projection ratio, then the volume of system can be larger, and complex structure degree can be higher, is unfavorable for the realization of product; And aspheric surface refraction-reflection type and free form surface refraction-reflection type, reflecting surface due to catoptron has its special curvature characteristic, so be conducive to the simplification of the aberration correction of system, the miniaturization of volume and structure, it is the current ultrashort out-of-focus projection modal combination in field.But, existing aspheric surface refraction-reflection type and free form surface refraction-reflection type short out-of-focus projection lens optical foundation structure are still comparatively complicated, comprise 11-14 sheet refractor, containing 3-5 aspheric surface, shank is long, production technology is poor, cost is high, and manufacturing technique requirent is high, and yield rate is low, these deficiencies have had a strong impact on the development of ultrashort out-of-focus projection technology, are the gordian technique difficult problems that this field needs to solve.
Summary of the invention
In view of above-mentioned condition, the invention provides a kind of eight groups ten ultralow projections of refraction-reflection type than projection lens foundation structure, make its lens optical system by reflecting system and dioptric system combination, have the projection ratio lower than 0.27: 1, under the prerequisite ensureing overall aberration excellence, lens construction achieves and simplifies to greatest extent, shortens shank length, improve production technology and projected picture brightness, reduce production cost.
Technical solution of the present invention is: a kind of eight groups ten ultralow projections of refraction-reflection type are than projection lens foundation structure, an object point on digital projector chip is a picture point by this lens imaging in screen, comprises the reflecting system and dioptric system that set gradually to the side of this object point from the side of this picture point; Wherein:
Reflecting system, comprise a convex surface even non-spherical reflector, reflecting surface is in screen side; With
Dioptric system, comprise seven groups of nine refractors, and an aperture diaphragm, the first lens that nine described refractors set gradually to the side of this object point from the side of this picture point, second lens, 3rd lens, 4th lens, 5th lens, 6th lens, 7th lens, 8th lens, 9th lens, wherein the 3rd lens and the 4th lens, 7th lens and the 8th lens are respectively two gummed mirror group, described first lens, second lens are negative curved month type, and convex surface all forward, 3rd lens are negative curved month type, and convex surface forward, 4th lens are biconvex, curvature absolute value is forward-facing large, 5th lens are positive curved month type, concave surface forward, 6th lens are positive curved month type, concave surface forward, 7th lens are biconvex, curvature absolute value is forward-facing little, 8th lens are negative curved month type, concave surface forward, 9th lens are biconvex, curvature absolute value is forward-facing large, described aperture diaphragm is arranged on the position between the 4th lens and the 5th lens, described reflecting system and dioptric system have identical primary optical axis, reflecting system is for being reflected through the light beam of dioptric system institute outgoing,
The first lens in described dioptric system are spherical lens, the convex surface face type of the second lens is sphere, concave surface face type is even aspheric surface, and the 3rd lens, the 4th lens, the 5th lens, the 6th lens, the 7th lens, the 8th lens, the 9th lens are spherical lens;
The ratio of the equivalent focal length absolute value of described reflecting system and the equivalent focal length absolute value of dioptric system is 9.5 ~ 13.0, and wherein the equivalent focal length of reflecting system is negative value, the equivalent focal length of dioptric system be on the occasion of;
Described reflecting system and the spacing of dioptric system are 0.39 ~ 0.51 with the ratio of the overall length of dioptric system;
Described refraction-reflection type projection lens anti-more than being 4.5 ~ 6.5;
Described refraction-reflection type projection lens is suitable for coloured light wavelength coverage: 430nm ~ 650nm.
In the present invention, described first lens adopt heavy crown system optical glass material; Described second lens adopt optical plastic or crown system optical glass material; Described 3rd lens, the 4th lens, the 5th lens, the 6th lens, the 7th lens, the 8th lens, the 9th lens adopt lanthanum flint system, flint system, barium crown system, fluorine crown system, fluorine crown system, dense flint system, fluorine crown system optical glass material successively.
In the present invention, involved refraction-reflection type projection lens foundation structure carries out focal length convergent-divergent in proportion, and suitably adjusting the matching relationship of each dominant aberration, the target surface that can meet 1LCD, 3LCD, 1DMD type of skill is of a size of the use of the digital projector of 0.55 ~ 0.7 inch of scope.
In the present invention, the arbitrary or several index plane in lens construction can be changed to aspheric surface, can to the aberration correction of whole optical system.
Indication of the present invention anti-more than refer to lens optical rear cut-off distance L ' and focal distance f ' the absolute value of ratio.
The beneficial effect that the present invention has is: use the projection lens that this foundation structure form design goes out, be made up of the dioptric system of the reflecting system and positive focal length with negative focal length, reflecting system is a convex surface even non-spherical reflector, dioptric system is only containing the even non-spherical lens of a slice optical plastic material and the spherical lens of eight optical glass materials, structure is simple, small, improve production technology and projected picture brightness, greatly reduce production cost and resetting difficulty, and there is the ultralow projection ratio lower than 0.27: 1.Object plane, after dioptric system, is first imaged on the reflecting surface of catoptron, then by reflective surface in screen, can project the picture of the enough large less TV distortion of high-quality, substantially reduce projector space at very short projector distance.In addition, optical plastic can be adopted also can to adopt crown system optical glass by the optical material of the non-spherical lens in dioptric system, when adopting crown system optical glass, by CNC Lapping & Polishing method, aspheric surface is processed, being suitable for the production and processing of smallest number, when adopting optical plastic, with injection molding method, aspheric surface being processed, be suitable for large batch of production and processing, further promote the fast development of digital ultrashort out-of-focus projection technology.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Fig. 2 is the ray tracing schematic diagram of Fig. 1.
Embodiment
Below in conjunction with accompanying drawing embodiment, the present invention is described in further detail, only for the beneficial effect explaining embodiments of the invention He have, not for limiting the scope of the invention.
The eight groups ten ultralow projections of refraction-reflection type are as shown in Figure 1 than projection lens foundation structure, an object point on digital projector chip C is a picture point by this lens imaging on screen A, comprises the reflecting system 11 and dioptric system 12 that set gradually to the side of this object point from the side of this picture point.Reflecting system 11 described in the present invention, comprises convex surface even non-spherical reflector 1101, and its reflecting surface, in screen A side, plays and increases field angle, balance aberration, correcting distorted effect.Described dioptric system 12, comprise oppositely set gradually corresponding to screen A the first lens 1201, second lens 1202, the 3rd lens 1203-1, the 4th lens 1203-2, aperture diaphragm 1204, the 5th lens 1205, the 6th lens 1206, the 7th lens 1207-1, the 8th lens 1207-2, the 9th lens 1208.Wherein the 3rd lens 1203-1 and the 4th lens 1203-2 forms a two gummed mirror group, play dispersed light focal power, correcting chromatic aberration, reduce the effect of senior aberration amount, 7th lens 1207-1 and the 8th lens 1207-2 forms a two gummed mirror group, play correcting chromatic aberration, increase back work distance from effect, first lens 1201 are negative curved month type, and convex surface (establishes camera lens when projecting duty forward, catoptron 1101 end is front, screen A holds as rear), play increase field angle, reduce eyeglass bore, widen the effect of back focus intercept, second lens 1202 are negative curved month type, and convex surface forward, concave surface face type is even aspheric surface, play increase field angle, improve relative aperture, balance off-axis aberration, simplify the effect of structure, 3rd lens 1203-1 is negative curved month type, and convex surface forward, 4th lens 1203-2 is biconvex, curvature absolute value is forward-facing large, 5th lens 1205, 6th lens 1206 are positive curved month type, and concave surface all forward, play and improve Large visual angle, miniaturization and picture element excellent between contradiction, 7th lens 1207-1 is biconvex, curvature absolute value is forward-facing little, 8th lens 1207-2 is negative curved month type, concave surface forward, 9th lens 1208 are biconvex, curvature absolute value is forward-facing large.Described aperture diaphragm 1204 is arranged between the 4th lens 1203-2 and the 5th lens 1205.The 6th lens 1206 in the present embodiment, the 7th lens 1207-1 and the 9th lens 1208 all adopt fluorine crown system optical glass material, play a part to widen back work distance from.In above-mentioned, the equivalent focal length of described reflecting system 11 is negative value, the equivalent focal length of dioptric system 12 be on the occasion of, the ratio of both absolute values is 9.5 ~ 13.0.Described reflecting system 11 is 0.39 ~ 0.51 with the ratio of the spacing of dioptric system 12 and the overall length of dioptric system 12.Described reflecting system 11 and dioptric system 12 have identical primary optical axis 10, and reflecting system 11 is for being reflected through the light beam of dioptric system 12 outgoing.In embodiments of the invention, the optical performance parameter of described camera lens is: focal distance f '=-4.7mm, relative aperture D/f '=1/2.2, and projection is than being 0.265: 1, and instead more than being 6.4, optical system overall length is 151mm, and wherein D is Entry pupil diameters.In embodiments of the invention, in the present invention, involved refraction-reflection type projection lens foundation structure carries out focal length convergent-divergent in proportion, and suitably adjusting the matching relationship of each dominant aberration, the target surface that can meet 1LCD, 3LCD, 1DMD type of skill is of a size of the use of the digital projector of 0.55 ~ 0.7 inch of scope.In the present invention, the first lens in described dioptric system are spherical lens, the convex surface face type of the second lens is sphere, and concave surface face type is even aspheric surface, and the 3rd lens, the 4th lens, the 5th lens, the 6th lens, the 7th lens, the 8th lens, the 9th lens are spherical lens.In the present invention, described first lens adopt heavy crown system optical glass material; Described second lens adopt optical plastic or crown system optical glass material; Described 3rd lens, the 4th lens, the 5th lens, the 6th lens, the 7th lens, the 8th lens, the 9th lens adopt lanthanum flint system, flint system, barium crown system, fluorine crown system, fluorine crown system, dense flint system, fluorine crown system optical glass material successively.In the present invention, involved refraction-reflection type projection lens anti-more than being 4.5 ~ 6.5.
Of the present invention instead more than refer to lens optical rear cut-off distance L ' and focal distance f ' the absolute value of ratio.
In the present invention, the arbitrary or several index plane in lens construction can be changed to aspheric surface, like this, by complicated design, sacrifice the aberration correction that processing technology is conducive to whole optical system.
Camera lens of the present invention is the digital projection camera lens of the ultralow projection ratio that a kind of refraction and reflection combine, it requires that very little projection image TV distorts, and require to there is very large picture from axle amount, require that the physical dimension of whole system is rationalized, miniaturization, its design optimization strategy is different from traditional total refraction numeral short out-of-focus projection camera lens simultaneously.First, according to design input requirements, calculate the picture of camera lens from axle amount, extrapolate the design image height of camera lens, again by projecting than the focal length extrapolating camera lens, then according to image height and the focal length of camera lens, set up suitable optical system model, namely first set up a total refraction short-focus lens structure, then extrapolated the focal length of reflecting system by the focal length of this total refraction camera lens.Finally, can antidromicity principle according to light path, lens optical structure is by reverse optical path design, set the basic optical parameter of whole optical system in software: image height, relative aperture, operation wavelength, object distance range, between lens imaging image planes and camera lens dioptric system, insert the equivalent parallel glass plate of certain thickness (thickness is different according to the difference of digital projector target surface size) simultaneously, for the inside colour splitting prism of analog digital projector, the camera lens designed so just well can balance the various aberrations that the inner colour splitting prism of digital projector causes when projecting.On this basis, adopt the Optimization Design that artificial and design software combines, this optical system is transformed, optimized, until this camera lens has good aberration quality, uniform illuminance of image plane and good manufacturability.Note upgrading and adjust various optimization target values at any time in optimizing process.
In order to embodiments of the invention are described, when camera lens equivalent focal length is 1, its Optic structure parameter is as follows:
S1 even aspheric surface parameter:
Conic constant (K) |
-20.32 |
4 rank coefficients (A) |
1.95e-006 |
6 rank coefficients (B) |
-2.21e-009 |
8 rank coefficients (C) |
1.47e-012 |
10 rank coefficients (D) |
-4.90e-016 |
12 rank coefficients (E) |
5.88e-020 |
S5 even aspheric surface parameter:
Conic constant (K) |
-0.55 |
4 rank coefficients (A) |
0.013 |
6 rank coefficients (B) |
-4.16e-003 |
8 rank coefficients (C) |
7.63e-004 |
10 rank coefficients (D) |
-6.67e-005 |
12 rank coefficients (E) |
2.36e-006 |
It is 430nm ~ 650nm that the lens optical structure of the embodiment of the present invention is suitable for look wavelength coverage.
Fig. 2 gives the ray tracing schematic diagram of the embodiment of the present invention.As can be seen from the figure the feature light a of each specific visual field of lens construction moves towards, and the incoming position of feature light a in each refractive lens surface and the reflection position in mirror surface.