CN114047664A - High-efficiency lighting device and single LCD projector optical system - Google Patents

Abstract

The invention provides a high-efficiency lighting device which comprises a condenser and a condensing collimating lens group which are sequentially arranged according to the light advancing direction. When the condenser is a light hopper, the condensing collimating lens group is a lens, and the emergent surface of the lens is a convex free-form surface. The invention also provides a single LCD projector optical system, which comprises the high-efficiency lighting device, an LED light source, an LCD light valve, a field lens, an imaging reflector and a projection lens, wherein the LED light source, the high-efficiency lighting device, the LCD light valve, the field lens, the imaging reflector and the projection lens are sequentially arranged according to the light advancing direction. The invention can obviously improve the illumination efficiency and the illumination uniformity of the existing single LCD projector illumination device which are limited by design and manufacture, can obviously reduce the slope ratio of the convex surface of the condenser lens and the manufacture difficulty, and has positive effects on improving the durability of the projector quality, the aesthetic feeling of the user watching experience and the like.

Description

High-efficiency lighting device and single LCD projector optical system

Technical Field

The invention relates to the technical field of projectors, in particular to a high-efficiency lighting device and a single LCD projector optical system.

Background

The light emitted from the LED light source of the current domestic single LCD projector is condensed and collimated by the illumination device and then illuminates the LCD light valve. Generally, the lighting device is a combination of a light funnel (also called a "hollow square cone condenser") and a fresnel lens (referred to as a "fresnel lens" for short) (referred to as a "light funnel lighting", the same applies hereinafter). The lighting device has the advantages of extremely low cost, simple manufacture, low lighting efficiency, low irradiation uniformity and poor product consistency due to the influence of the material performance and the manufacture precision of the light hopper. Referring to fig. 4, the single LCD projector optical system including the light hopper illumination is sequentially provided with an LED light source 1 ", a light hopper 21", a front phenanthrene mirror 32 "(for collimation), an LCD light valve 4", a field lens 5 "(commonly used as a phenanthrene mirror and called as a" rear phenanthrene mirror "), an imaging mirror 6", and a projection lens 7 "in the light traveling direction. Usually, the LED light source 1 ", the inlet of the light funnel 21", the outlet of the light funnel 21 "and the front mirror 32" are sequentially attached to each other, and a certain gap is left between the materials in fig. 4 for easy observation and understanding.

Or the lighting device is a combination mode of a collecting lens and a film mirror (collecting lens lighting for short, the same is applied later), and the cost and the lighting efficiency of the lighting device are slightly higher than those of the lighting mode of the light hopper in practice. Referring to fig. 5, a single LCD projector optical system including condenser illumination is sequentially disposed, in a light traveling direction, an LED light source 1 ', a condenser 2', a front mirror 32 ', an LCD light valve 4', a field lens 5 ', an imaging mirror 6', and a projection lens 7 ', where the condenser 2' is generally a plano-convex free-form surface lens and a plane is an incident plane. The disadvantage of this approach is that the refractive index of the material of the collecting mirror 2 'is low (because the material with higher refractive index is too high in cost, a single LCD projector is very sensitive to cost), and in order to obtain higher light collecting efficiency, the slope ratio of the exit surface (convex surface) of the collecting mirror 2' must be designed to be very large at the portion outside the solid angle corresponding to the principal ray, which results in difficulty in manufacturing the collecting mirror 2 'and low manufacturing yield, and difficulty in designing and manufacturing the uniformity of illumination of the LCD light valve 4'. In view of the cost, there is a great cost pressure on improving the transmittance by plating an antireflection film on the convex surface of the condenser lens 2 ', so that almost no film is selected, and thus the transmission efficiency of the principal ray and the transmission efficiency of the marginal ray (outside the solid angle of the principal ray) of the condenser lens 2' are further reduced.

In long-term single LCD projector development and production practices, there is no good way to solve the above existing problems. In the actual product, the illumination efficiency of the illumination mode of fig. 4 is difficult to break through 55% -60%, and the illumination uniformity, i.e. the minimum illumination value/the maximum illumination value on the LCD light valve, is only about 35% -45%. In the condenser illumination mode shown in fig. 5, for example, the condenser 2' is limited to use a material with a lower refractive index due to cost pressure, and even when the design is particularly excellent, the illumination efficiency is not as high as about 60% -63% (on the premise that reflection loss of two surfaces of the condenser is not considered), and the illumination uniformity is only about 50% -55%, so that the weight of the projector product manufactured by using such parameter indexes is increased in the proportion of user complaints with the increase of the demand of the consumer on the video product experience.

In the conventional illumination mode, on the premise of complying with the transmission rule of optical expansion (abbreviated as etendue, hereinafter the same), the high-efficiency illumination device and the single LCD projector optical system designed by the invention can significantly improve the illumination efficiency and the illumination uniformity, and can significantly reduce the slope ratio of the convex surface of the condenser lens and the manufacturing difficulty, thereby playing a positive role in improving the durability of the quality of the projector and the aesthetic feeling of the user viewing experience.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a high-efficiency lighting device and a single LCD projector optical system, can obviously improve the lighting efficiency and the illumination uniformity, can obviously reduce the slope ratio of the convex surface of a condenser lens and the manufacturing difficulty, and has positive effects of improving the durability of the quality of a projector, the aesthetic feeling of watching experience of a user and the like.

In order to achieve the above object, the present invention provides an efficient illumination device, which comprises a condenser and a condensing collimating lens set, which are arranged in sequence according to the light traveling direction.

When the condenser is a light hopper, the condensing collimating lens group is a lens, and the emergent surface of the lens is a convex free-form surface.

Or the condenser is a condenser lens, when the emergent surface of the condenser lens is a free curved surface of a convex surface type, the condensing collimating lens group is a lens, the lens is any one of a plane convex surface type, a concave-convex surface type or a double convex surface type, and the emergent surface of the lens is the free curved surface of the convex surface type.

Or the condenser is the condensing lens, when the exit surface of condensing lens is the free curved surface of convex surface type, the condensing collimating lens group includes first lens and the second lens that set gradually according to light advancing direction, first lens is any one of plano-convex surface type, concave-convex surface type or biconvex surface type, just the exit surface of first lens is the free curved surface of convex surface type, the second lens is fresnel lens.

The invention also provides a single LCD projector optical system, which comprises the high-efficiency lighting device, an LED light source, an LCD light valve, a field lens, an imaging reflector and a projection lens, wherein the LED light source, the high-efficiency lighting device, the LCD light valve, the field lens, the imaging reflector and the projection lens are sequentially arranged according to the light advancing direction.

The invention has the beneficial effects that:

the high-efficiency lighting device comprises a condenser and a condensing collimating lens group, wherein the condenser is a light hopper or a condenser, the condensing collimating lens group is a lens or comprises a first lens and a second lens, the use of the lenses overcomes the defects of the existing front mirror and maintains the regular transmission of the optical spread, and the lighting rays from the condenser can be subjected to optical design (needing to be combined with the whole optical system) and manufacture on the basic level of the lenses, so that the LCD light valve can obtain the lighting performance which tends to be ideal in design, including but not limited to the obvious improvement of the lighting efficiency and the lighting uniformity.

The lens and the phenanthrene lens are both of plano-convex lens (or equivalent) structures, but the lens has much more freedom than the operable space of the phenanthrene lens due to the selection of the thickness, the surface type (continuous transition of a free curved surface) of an emergent surface and the principle of the phenanthrene lens are also different essentially, and simultaneously, the essential adverse factors such as a phenanthrene lens invalid region, inclined plane total reflection loss and the like are completely avoided. Therefore, the illumination efficiency of the invention can easily break through more than 68-70%, and the illumination uniformity of the LCD light valve can easily break through more than 75-80% according to the metering mode, so that the illumination uniformity effect of using a real optical integrator such as a fly-eye lens array is obtained, and the experience of a user on a projection picture is radically improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a perspective view of a first embodiment of an optical system for a single LCD projector according to the present invention;

FIG. 2 is a perspective view of a second embodiment of an optical system of a single LCD projector according to the present invention;

FIG. 3 is a perspective view of a third embodiment of the optical system of the single LCD projector according to the present invention;

FIG. 4 is a schematic diagram of a prior art projector optical system incorporating a bucket illumination technique;

FIG. 5 is a schematic diagram of a prior art projector optical system incorporating condenser illumination technology;

FIG. 6 is a schematic view of the configuration of the collection optic of FIG. 5;

fig. 7 is a schematic diagram of a further illustrative structure of the collecting mirror of fig. 5.

Detailed Description

The following detailed description of the present invention is given for the purpose of better understanding technical solutions of the present invention by those skilled in the art, and the present description is only exemplary and explanatory and should not be construed as limiting the scope of the present invention in any way.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

It is to be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like are used in a generic and descriptive sense only and not for purposes of limitation, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like are used in the generic and descriptive sense only and not for purposes of limitation, as the term is used in the generic and descriptive sense, and not for purposes of limitation, unless otherwise specified or implied, and the specific reference to a device or element is intended to be a reference to a particular element, structure, or component. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The advantages of the high-efficiency lighting device designed by the invention are described in combination with a single LCD projector optical system, the high-efficiency lighting device can obviously improve the lighting efficiency and the illumination uniformity, can obviously reduce the slope ratio of the convex surface of the condenser lens and the manufacturing difficulty, has positive effects on improving the durability of the quality of a projector, the aesthetic feeling of the watching experience of a user and the like,

example one

Referring to fig. 1, the optical system of the single LCD projector provided in this embodiment includes an LED light source 1, a high-efficiency illumination device, an LCD light valve 4, a field lens 5, an imaging mirror 6, and a projection lens 7. The LED light source 1, the high-efficiency lighting device, the LCD light valve 4, the field lens 5, the imaging reflector 6 and the projection lens 7 are sequentially arranged according to the light advancing direction. The high-efficiency lighting device comprises a condenser and a condensing collimating lens group which are sequentially arranged according to the light advancing direction. The condenser is a condenser 2, the incident surface of the condenser 2 is a plane, and the emergent surface of the condenser 2 is a convex surface, at the moment, the condenser 2 is commonly called as a plane-convex surface type, and the emergent surface of the condenser 2 is a convex surface type free-form surface; if the incident surface of the condenser lens 2 is a concave surface and the emergent surface is a convex surface, the condenser lens 2 is commonly called as a concave-convex surface type; if the incident surface of the condenser 2 is a convex surface and the exit surface is a convex surface, the condenser 2 is commonly referred to as a biconvex type.

In this embodiment, the condensing collimating lens group is a lens 3, the lens 3 is a plane-convex type, and an exit surface of the lens 3 is a convex free-form surface. The lens 3 may of course also be of a meniscus type or a biconvex type. The plano-convex lens is adopted in the embodiment because the plano-convex lens is simple to manufacture and has higher cost performance compared with a concave-convex lens or a biconvex lens.

The lens 3 has the obvious function of reshaping the light and of collimating the light that strikes the LCD light valve 4.

Referring to fig. 4, in virtually any single LCD projector, the length of the light hopper 21 "is limited relatively, one is the trade-off between the number of reflections on the inner wall of the light hopper 21" and the reflection loss, and the other is the size of the projector. The focal length of the former phenanthrene mirror 32 "(the tooth surface is installed towards the LCD light valve) is generally correspondingly smaller or shorter (the focal length of most projector phenanthrene mirrors 32" is smaller than the diagonal dimension of the LCD light valve 4 "), because the light valve size used by the existing single LCD projector is basically within 5 inches, and the focal length of the former phenanthrene mirror 32" is far smaller than 125mm, the loss of the front phenanthrene mirror 32 "to the illumination light is very large, including but not limited to dead areas (commonly called dead areas) of the tooth (thread) surface and total reflection loss of the inclined surface of the tooth, which can reach more than 20% seriously, even if the tooth surface of the phenanthrene mirror is coated with an antireflection film, the antireflection film cannot be used for help. Because when light rays are emitted from the light dense matter to the light sparse matter, if total reflection occurs, the mode of plating an antireflection film on an interface is relied on to avoid the total reflection, and the method has no significance.

For the light from the light hopper 21 ", the light loss of the front phenanthrene mirror 32" is not limited to the above efficiency, and for the fresnel-shaped thin lens, no matter the molding process or the injection molding process is adopted, the manufacturing process of the phenanthrene mirror can hardly realize the surface shape effect of the optical design, even if the surface shape of the effective inclined plane (also called effective conical surface) of the tooth surface is designed to be reasonably corrected and optimized, so that the light spread of the illumination light can reduce the overflow as much as possible, but the manufactured phenanthrene mirror product can hardly realize the optimized design effect at all.

The positive effects or disadvantages of the optical system are just opposite for the front field lens used for the illumination end collimation of the LCD light valve and the rear field lens (with the tooth surface facing the LCD light valve) used as the imaging end field lens, i.e. the field lens. Referring to fig. 4 and 5, the field lens 5' or 5 ″ is a field lens (typically 1.5mm to 2mm thick) and is very significant in reducing the imaging aberration. The front mirror 32' or 32 "used for collimation significantly deteriorates aberration, because of its too small thickness (typically 1.5mm to 2mm), which is also a significant cause of the blooming of the illumination light.

The deficiencies of the conventional condenser illumination technique shown in fig. 5, including further description of the condenser 2 'and the preflight 32', are discussed in example two.

With continued reference to fig. 1, the lens 3 of the present embodiment not only overcomes the disadvantages of the conventional front-view mirror and maintains the regular transmission of the optical spread, but also for the illumination light from the collecting mirror 2, the illumination performance of the LCD light valve 4, which is close to the ideal design, including but not limited to the significant improvement of the illumination efficiency and the illumination uniformity, can be obtained by the optical design (which needs to be performed in conjunction with the whole optical system) and the fabrication of the lens 3 at the basic level. Because the lens 3 and the phenanthrene mirror are both flat convex lens (or equivalent) structures, the lens 3 has much more freedom than the operable space of the phenanthrene mirror because of the selection of the thickness, the surface type (free curved surface continuous transition) of the emergent surface and the principle of the phenanthrene mirror are also different essentially, and simultaneously, the essential adverse factors such as the phenanthrene mirror ineffective area, the inclined plane total reflection loss of teeth and the like do not exist completely. Therefore, the illumination efficiency of the present embodiment can easily exceed 68% to 70% and the illumination uniformity of the LCD light valve 4 according to the foregoing measurement manner can also easily exceed 75% to 80%, so as to obtain the illumination uniformity effect of using a real optical integrator such as a fly-eye lens array, thereby providing a fundamental improvement to the user experience of projecting pictures.

The embodiment is very suitable for the occasion that the size of the LCD light valve is less than or equal to 3 inches, so that the volume of the projector still belongs to the range of the same size specification compared with the optical system of the traditional principle shown in figures 4 and 5. Meanwhile, due to the small size of the LCD light valve, the cost increase of the lens 3 (after the cost of the lens 3 minus the cost of the front mirror 32') is negligible, so that the projector still maintains a very high cost performance.

In addition, for the application of the smaller size of the LCD light valve, if the projector outputs the same brightness, the smaller size of the LCD light valve will tend to mean the greater energy density of the light beam impinging on the front mirror 32'. It is apparent that the durability of the lens 3 using the glass material is substantially different from that of the front mirror 32' using the acryl material (PMMA).

Example two:

referring to fig. 2, the optical system of the single LCD projector provided in this embodiment includes an LED light source 1, a high-efficiency illumination device, an LCD light valve 4, a field lens 5, an imaging mirror 6, and a projection lens 7. The LED light source 1, the high-efficiency lighting device, the LCD light valve 4, the field lens 5, the imaging reflector 6 and the projection lens 7 are sequentially arranged according to the light advancing direction. The high-efficiency lighting device comprises a condenser and a condensing collimating lens group which are sequentially arranged according to the light advancing direction. In this embodiment, the condenser is a condenser 2, the condenser 2 is a flat convex surface type, and an exit surface of the condenser 2 is a convex free-form surface.

In this embodiment, the condensing collimating lens group includes a first lens 31 and a second lens 32 sequentially arranged in the light traveling direction. The first lens 31 is a plano-convex type, the emergent surface is a convex free-form surface, the second lens 32 is a fresnel lens, and the first lens 31 is not limited to the plano-convex type.

As mentioned above with continued reference to fig. 1, when considering cost performance, the application of the technique of the first embodiment to a larger LCD light valve (e.g. 4.5 inches to 5 inches) results in a significant increase in cost and weight of the projector due to the corresponding large increase in aperture of the lens 3 (the clear aperture needs to be larger than the size of the LCD light valve). Therefore, the present embodiment can ensure the cost, weight, etc. of the projector to be maintained within the ideal price and range on the premise of ensuring the illumination efficiency and the illumination uniformity to be significantly improved.

It is apparent that the limitations of the condenser illumination technique shown in fig. 5 have been described above. Aiming at an improvement method of the optical system in fig. 5, which is expected to improve the illumination efficiency and the illumination uniformity, theoretically, the thickness of the condenser 2 ' is increased, so that the slope ratio of the emergent surface of the condenser 2 ' can be further increased, the solid angle of light rays irradiating the front phenanthrene mirror 32 ' is compressed, the distance between the front phenanthrene mirror 32 ' and the condenser 2 ' can be increased, the focal length of the front phenanthrene mirror 32 ' is increased, and the light loss of the tooth surface of the front phenanthrene mirror 32 ' is reduced, so that the illumination efficiency is improved. Meanwhile, the surface shape of the emergent surface of the condenser 2 'is optimized, so that better uniformity is obtained when the LCD light valve 4' is illuminated. Unfortunately, these approaches are only theoretical and are completely impractical in practice.

Referring to fig. 5-7, point a is the central point of the incident surface of the condenser 2 ', point o is the vertex of the exit surface of the condenser 2', and straight line ao is the optical axis. Because the condenser 2 ' has the characteristic of rotational symmetry around the optical axis ao, the condenser 2 ' is cut open by using a plane containing a straight line ao arbitrarily, and a section of a micro-length element (infinitesimal) line segment is taken arbitrarily on the contour line (on the convex surface) of the cutting surface of the condenser 2 ' to be used as a perpendicular line of the infinitesimal line segment. The perpendicular line intersects with the infinitesimal line segment at the point c and intersects with the optical axis at the point b, and the tangent value of the included angle theta between the optical axis ao and the perpendicular line bc is the slope ratio of the infinitesimal line segment. It can be easily seen from fig. 6 that the farther from the vertex o of the condenser 2 ', the greater the slope ratio, which is generally said to mean the steeper the slope of the infinitesimal line segment with respect to the incident plane of the condenser 2'.

Any light ray de emitted by the LED light source 1 ' enters from the e point of the condenser 2 ', is refracted by the condenser 2 ', then is emitted from the f point of the emergent surface, and continues to advance along fg.

When the slope ratio of the condenser 2 'is larger than a certain value, total reflection occurs at the f point to destroy the transmission of light, and simultaneously, the cost of the condenser 2' is greatly increased during manufacturing and antireflection film plating, and the quality is difficult to guarantee. These fundamentally limit the efficiency of the condenser illumination technique (shown in fig. 5). Due to the large slope ratio of the free-form surface type and the aberrations of the front mirror 32 ', an uncontrolled spill of illumination etendue is caused and, in general, a severe non-uniformity of illumination (local bright spots) on the LCD light valve 4' is caused.

Reducing the slope ratio of the condenser 2 ' can increase the solid angle of the light irradiating the front phenanthrene mirror 32 ', and to achieve reasonable collimation (the illumination light satisfies the optical spread of the LCD light valve 4 limited by the projection lens 7) and illumination efficiency that is not seriously reduced (for example, by more than 30%), it is necessary to further reduce the focal length of the front phenanthrene mirror 32 ', which further increases the loss of the tooth surface efficiency of the front phenanthrene mirror 32 ', and further increases the aberration (also has unfavorable indexes such as vignetting) of the front phenanthrene mirror 32 '.

Or the slope ratio of the condenser 2 'is increased, and after the slope ratio of the condenser 2' is increased to a certain degree, the steep curved surface can not ensure the dimensional accuracy and the required finish degree at the time of manufacturing, so that the slope ratio is increased and the curved surface profile is optimized almost no longer. This is also the fundamental engineering limitation of the prior art represented by fig. 5.

Referring to fig. 2, in the present embodiment, a free-form surface (the first lens 31) is added to shape the light, so that the exit surface of the condenser lens 2 does not need a slope ratio as large as that, and an ideal condensing efficiency can be obtained for the LED light source 1. At the same time, the light illuminating the LCD light valve 4 is shaped, adding an easier design dimension. Naturally, the second lens 32 can significantly increase the focal length value, reduce the adverse effects of aberrations and vignetting, and improve the transmission efficiency of the tooth surface without significantly increasing the installation distance.

The added first lens 31 is close to the condenser lens 2 when being installed, so that the indexes of geometric aperture, thickness and the like are not too large, and the added cost is very limited. It is worth to increase the cost slightly, compared to the improvement of the illumination efficiency, the improvement of the illumination uniformity, the manufacturing yield of the condenser lens 2, the reduction of the cost, and the like.

The embodiment is especially suitable for the condition that the size of the LCD light valve is larger, such as more than or equal to 4.5 inches.

Example three:

referring to fig. 3, the optical system of the single LCD projector provided in this embodiment includes an LED light source 1, a high-efficiency illumination device, an LCD light valve 4, a field lens 5, an imaging mirror 6, and a projection lens 7. The LED light source 1, the high-efficiency lighting device, the LCD light valve 4, the field lens 5, the imaging reflector 6 and the projection lens 7 are sequentially arranged according to the light advancing direction. The high-efficiency lighting device comprises a condenser and a condensing collimating lens group which are sequentially arranged according to the light advancing direction. In this embodiment, the condenser is a light funnel 21.

In this embodiment, the condensing collimating lens assembly is a lens 3, the lens 3 is a plane-convex type, and the exit surface is a convex free-form surface.

In this embodiment, the light emitting surface of the LED light source 1, the inlet of the light funnel 21, the outlet of the light funnel 21, and the incident surface of the lens 3 are sequentially attached to each other, and a certain distance is intentionally left between the materials in fig. 3 for easy observation and understanding.

As described above, in the present embodiment, for the existing light hopper lighting technical manner, a great improvement in the illumination uniformity can be achieved, after the lens 3 is reasonably designed, the illumination uniformity of the LCD light valve 4 can reach more than 80% -85%, but if the LCD light valve 4 is large in size, the present embodiment is similar to the present embodiment, the cost performance and the weight of the projector are sacrificed as appropriate, but for the current higher and higher standard appeal of consumers, the present embodiment still has a better implementation value, and particularly, a single LCD projector with a relatively higher end is subdivided into markets.

Referring to fig. 4, according to the optical principle and the actual product condition of a single LCD projector, the length of the light funnel 21 "is very limited, so the focal length of the front mirror 32" is also required to be very short, which causes the light emitted from the LED light source 1 "to overflow (increase irregularly) after passing through the light funnel 21" and the front mirror 32 ", which is also a significant reason for the difficulty in dissipating heat of the LCD light valve 4" (many lights illuminating the LCD light valve 4 "are useless). An important factor here is that the front mirror 32 "cannot homogenize the light emitted from the funnel 21" except for generating a simple refraction effect, and the uniform illumination of the light depends on the light homogenizing effect of the funnel 21 ", and the length of the funnel 21" is relatively short, so that the light homogenizing performance itself is not good, i.e. a large amount of light is collected in the center of the LCD light valve 4 ".

In this embodiment, since the thickness of the lens 3 (usually 20mm-28mm) is much greater than that of the front mirror 32 ″, the light rays originally superimposed on the center of the LCD light valve are changed to be irradiated on other areas of the LCD light valve due to the significant and purposeful increase of the optical path, so as to achieve a further light-equalizing effect, and significantly improve the uniformity of the irradiated LCD light valve 4.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (2)

1. A high-efficiency lighting device is characterized by comprising a condenser and a condensing collimating lens group which are sequentially arranged according to the light advancing direction;

when the condenser is a light hopper (21), the condensing collimating lens group is a lens (3), and the emergent surface of the lens (3) is a convex free-form surface;

or the condenser is a condenser lens (2), when the emergent surface of the condenser lens (2) is a free curved surface of a convex surface type, the condensing collimation lens group is a lens (3), the lens (3) is any one of a plane convex surface type, a concave-convex surface type or a double convex surface type, and the emergent surface of the lens (3) is a free curved surface of a convex surface type;

or the condenser is condensing lens (2), when the exit surface of condensing lens (2) is the free curved surface of convex surface type, spotlight collimating lens group is including first lens (31) and second lens (32) that set gradually according to light advancing direction, first lens (31) are any one of plano-convex surface type, concave-convex surface type or biconvex surface type, just the exit surface of first lens (31) is the free curved surface of convex surface type, second lens (32) are fresnel lens.

2. An optical system of a single LCD projector, comprising the high-efficiency lighting device of claim 1, further comprising an LED light source (1), an LCD light valve (4), a field lens (5), an imaging reflector (6) and a projection lens (7), wherein the LED light source (1), the high-efficiency lighting device, the LCD light valve (4), the field lens (5), the imaging reflector (6) and the projection lens (7) are sequentially arranged according to the light traveling direction.

Images