Novel Kohler lighting device and projector optical system

Abstract

The novel Kohler lighting device comprises an LED light source, a condenser, a collimating lens, a hollow light guide rod and an LCD light valve which are sequentially arranged in the light advancing direction, and a reflecting film is arranged on the inner wall of the hollow light guide rod; the incident end of the hollow light guide rod is attached to the emergent face of the collimating lens, and the emergent end of the hollow light guide rod is attached to the incident face of the LCD light valve. Or the LED light source, the condenser, the collimating lens, the thin glass plate, the hollow light guide bar and the LCD light valve are sequentially arranged in the light advancing direction. A reflecting film is arranged on the inner wall of the hollow light guide rod; and the hollow light guide rod is filled with a non-gaseous transparent optical medium. For the LCD light valve with a small size, the illumination efficiency can be improved to 85% or above, the irradiation uniformity can be improved to 50% or above, the size of an optical system of the projector cannot be obviously increased, the projector can better adapt to market requirements in a new period, and industrial products are guided to develop to a higher level.

Description

Technical Field

[0001] The present invention belongs to the technical field of projectors, and in particular relates to a novel Kohler lighting device and a projector optical system. Background Art

[0002] Domestic single LCD projectors have always used a simple Kohler lighting method or system (hereinafter referred to as "Kohler lighting", the same below), see Figure 3 、 Figure 4 The following figure shows a typical lighting method in the industry. It is well known that Kohler illumination has the advantages of simple structure, high lighting efficiency, and high lighting uniformity. Compared with other lighting technologies that do not use optical integrators, Kohler illumination theoretically eliminates localized high-heat spots on the illuminated object surface. These advantages are extremely beneficial for single-LCD projectors.

[0003] The above advantages have two prerequisites. The first is that they only hold true when the technical standards for measurement are not too high. In other words, if a low technical standard is used to evaluate an actual single-LCD projector, Kohler illumination is very suitable. On the contrary, apart from the advantage of "simple structure", advantages such as high lighting efficiency, high uniformity, and the absence of local high-heat spots are almost not true in actual conditions. Another prerequisite is that Kohler illumination only has the above advantages when the projection light source is a point light source in the mathematical concept or is infinitely close to a point light source of physical size. Figure 3 、 Figure 4 The figure shows the light spot envelope when a point light source is used. In practice, single LCD projectors are not necessarily related to the ideal indicator of a point light source.

[0004] Even if a single-LCD projector uses a complex optical integration device and truly efficient critical illumination, it would be impractical in the market. Because the LCD light valve is large, the cost of optical materials would increase significantly. Compared with 3LCD and DLP projectors, whose light valve area is almost two orders of magnitude smaller, single-LCD projectors are difficult to compete with.

[0005] Domestic single-LCD projectors have come a long way over the past three decades. The product's definition has evolved from simply providing a solution to a problem to a mature, high-quality, and cost-effective solution. However, significant overcapacity exists. Therefore, innovation is essential to address the current low-efficiency and low-uniformity Kohler lighting system, adapting to the demands of the new era and leading the industry to higher product standards. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a new Kohler lighting device. The present invention is aimed at smaller-sized LCD light valves, and the lighting efficiency can be increased to more than 85%, the uniformity of illumination can be increased to more than 50%, and the volume of the projector optical system will not be significantly increased. It can better adapt to the market demand of the new era and lead the industry products to a higher level of development.

[0007] To achieve the above-mentioned objectives, the present invention provides a novel Kohler lighting device, comprising an LED light source, a condenser, a collimating lens, a hollow light guide rod, and an LCD light valve, which are arranged in sequence according to the direction of light travel; the inner wall of the hollow light guide rod is provided with a reflective film; the incident end of the hollow light guide rod is in contact with the exit surface of the collimating lens, and the exit end of the hollow light guide rod is in contact with the incident surface of the LCD light valve.

[0008] Let the long side of the LCD light valve display window be a, the short side be b, the diagonal length be Φ, the long side of the light-transmitting cross-section of the hollow light guide rod be ≥a and ≤1.02a; the short side of the light-transmitting cross-section of the hollow light guide rod be ≥b and ≤1.02b; the length of the hollow light guide rod be ≥0.1φ.

[0009] Furthermore, the collimating lens is a Fresnel lens, the refractive index of the material of the collimating lens is n, the plane of the Fresnel lens is the incident surface, the tooth surface is the exit surface, and the thickness from the plane to the tooth root of the tooth surface is c; the concentrator is a hollow square cone concentrator, and the exit surface of the concentrator is in contact with the incident surface of the collimating lens; the corresponding angle of the aperture designed for the LCD light valve on the projector optical system is θ.

[0010] The exit surface of the hollow square cone concentrator And ≤1.02a.

[0011] The exit surface of the hollow square cone concentrator And ≤1.02b.

[0012] The present invention provides a novel Kohler lighting device, comprising an LED light source, a condenser, a collimating lens, a thin glass plate, a hollow light guide rod, and an LCD light valve, which are arranged in sequence according to the direction of light travel; the collimating lens is a Fresnel lens, the exit surface of which is in contact with the incident surface of the thin glass plate; the inner wall of the hollow light guide rod is provided with a reflective film; the incident end of the hollow light guide rod is in contact with the exit surface of the thin glass plate, and the exit end of the hollow light guide rod is in contact with the incident surface of the LCD light valve; the interior of the hollow light guide rod is filled with a non-gaseous transparent optical medium.

[0013] Let the long side of the LCD light valve display window be a, the short side be b, and the diagonal length be Φ; the refractive index of the transparent optical medium be n1; then the long side of the light-transmitting cross-section of the hollow light guide rod be ≥a, and ≤1.02a; the short side of the light-transmitting cross-section of the hollow light guide rod be ≥b, and ≤1.02b; the optical length of the hollow light guide rod in the transparent optical medium be ≥0.1n1Φ.

[0014] Furthermore, let the refractive index of the material of the collimating lens be n; the plane of the collimating lens be the incident surface, the tooth surface be the exit surface, and the thickness from the plane to the tooth root of the tooth surface be c; the concentrator be a hollow square cone concentrator, and the exit surface of the concentrator be in contact with the incident surface of the collimating lens; and the corresponding angle of the aperture designed for the LCD light valve on the projector optical system be θ.

[0015] The exit surface of the hollow square cone concentrator And ≤1.02a.

[0016] The exit surface of the hollow square cone concentrator And ≤1.02b.

[0017] A projector optical system includes the novel Kohler illumination device, and also includes conventional configurations such as a field lens and a projection lens.

[0018] The beneficial effects of the present invention are as follows: the present invention inserts a hollow light guide rod between the collimating lens and the LCD light valve, or inserts a hollow light guide rod and a thin glass plate between the collimating lens and the LCD light valve; the interior of the hollow light guide rod is filled with a non-gaseous transparent optical medium; the transparent optical medium has a heat-conducting effect on the LCD light valve while changing the optical path and illuminating the solid angle, thereby directly improving the heat dissipation effect of the LCD light valve; the inner wall of the hollow light guide rod is provided with a reflective film; the hollow light guide rod matches the display window size of the LCD light valve; the edge light lost by Köhler illumination is reflected back through the hollow light guide rod and is completely utilized by the projection lens, thereby effectively improving the lighting efficiency, so that the lighting efficiency can be increased to more than 85%; at the same time, the lighting light at the edge of the LCD light valve display window is increased, which can effectively improve the uniformity of the lighting, and can be increased by at least 5% without significantly increasing the volume of the projector optical system, so that the uniformity of the lighting is increased to more than 50%. The present invention is targeted at smaller-sized LCD light valves and has excellent adaptability in improving lighting efficiency and uniformity. It can better meet the market demands of the new era and lead the development of industry products to a higher level. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Schematic diagram of embodiment 1 of the present invention;

[0021] Figure 2 This is a schematic diagram of the second embodiment of the present invention;

[0022] Figure 3 The following is a diagram of a typical existing lighting system using lens focusing;

[0023] Figure 4 This is a diagram of a typical existing lighting system using a light bucket for focusing;

[0024] Figure 5 for Figure 4 Schematic diagram in practice;

[0025] Figure 6 A schematic diagram of a public innovative technology. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0027] It should be noted that similar reference numerals denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in the subsequent drawings.

[0028] It should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate and simplify the description of the present invention and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0029] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0030] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] Example 1:

[0032] See also Figure 1 As shown, this embodiment provides a novel Kohler illumination device, comprising an LED light source 1, a condenser 2, a collimating lens 3, a hollow light guide rod 5, and an LCD light valve 7, which are arranged in sequence according to the direction of light travel; the inner wall of the hollow light guide rod 5 is provided with a reflective film; the incident end of the hollow light guide rod 5 is in contact with the exit surface of the collimating lens 3, and the exit end of the hollow light guide rod 5 is in contact with the incident surface of the LCD light valve 7.

[0033] Let the long side of the display window of the LCD light valve 7 be a, the short side be b, the diagonal length be Φ, the long side of the light-transmitting cross-section of the hollow light guide rod 5 be ≥a, and ≤1.02a; the short side of the light-transmitting cross-section of the hollow light guide rod 5 be ≥b, and ≤1.02b; the length of the hollow light guide rod 5 be ≥0.1φ.

[0034] In this embodiment, a hollow light guide rod 5 is inserted between the collimating lens 3 and the LCD light valve 7. The inner wall of the hollow light guide rod 5 is provided with a reflective film. The hollow light guide rod 5 matches the display window size of the LCD light valve 7. The edge light lost by Köhler illumination is reflected back by the hollow light guide rod 5 and fully utilized by the projection lens, thereby effectively improving the lighting efficiency. In practice, the lighting efficiency can be increased to over 85%. At the same time, the lighting light at the edge of the display window of the LCD light valve 7 is increased, which can effectively improve the uniformity of the lighting. Without significantly increasing the volume of the projector optical system, the uniformity of the lighting can be increased by at least 5%, so that the uniformity of the lighting is increased to over 50%.

[0035] In this embodiment, the collimating lens 3 is a Fresnel lens, and the refractive index of the material of the collimating lens 3 is n (usually PMMA material, and the refractive index n is based on actual measurement after pressing), the plane of the Fresnel lens is the incident surface, the tooth surface is the exit surface, and the thickness from the plane to the tooth root of the tooth surface is c; the concentrator 2 is a hollow square cone concentrator, and the exit surface of the concentrator 2 is aligned with the incident surface of the collimating lens 3; the aperture (i.e., F#, F number or Fno, different names but the same meaning) designed for the LCD light valve 7 on the projector optical system corresponds to an angle θ; the exit surface of the hollow square cone concentrator is and ≤1.02a; the hollow square cone-shaped focusing

[0036] The exit surface of the device And ≤1.02b. This limitation is based on the actual light

[0037] In the design, the effective range of the possible improvement of lighting efficiency and uniformity is: if ≥1.02a (or b), the improvement is limited and tends to 0 with further increase; if <a (or b) Although lighting efficiency may increase more, uniformity may not improve or may be worse.

[0038] These all require extensive engineering experience to make the right trade-offs, in order to meet market demand and avoid closed-door development.

[0039] Example 2:

[0040] See also Figure 2 As shown, this embodiment provides a novel Kohler lighting device, comprising an LED light source 1, a condenser 2, a collimating lens 3, a thin glass plate 4, a hollow light guide rod 5, and an LCD light valve 7, which are arranged in sequence according to the direction of light travel; the collimating lens 3 is a Fresnel lens, and its exit surface is in contact with the incident surface of the thin glass plate 4; the inner wall of the hollow light guide rod 5 is provided with a reflective film; the incident end of the hollow light guide rod 5 is in contact with the exit surface of the thin glass plate 4, and the exit end of the hollow light guide rod 5 is in contact with the incident surface of the LCD light valve 7; the interior of the hollow light guide rod 5 is filled with a non-gaseous transparent optical medium 6.

[0041] Let the long side of the display window of the LCD light valve 7 be a, the short side be b, and the diagonal length be Φ; the refractive index of the transparent optical medium 6 be n1; then the long side of the light-transmitting cross-section of the hollow light guide rod 5 be ≥a, and ≤1.02a; the short side of the light-transmitting cross-section of the hollow light guide rod 5 be ≥b, and ≤1.02b; the optical length of the hollow light guide rod 5 in the transparent optical medium 6 be ≥0.1n1Φ.

[0042] In this embodiment, a hollow light guide rod 5 and a thin glass plate 4 are inserted between the collimating lens 3 and the LCD light valve 7. The inner wall of the hollow light guide rod 5 is provided with a reflective film, and the interior of the hollow light guide rod 5 is filled with a non-gaseous transparent optical medium 6. While changing the optical path and illuminating the solid angle, the transparent optical medium 6 has a heat-conducting effect on the LCD light valve 7, directly improving the heat dissipation effect of the LCD light valve 7. The hollow light guide rod 5 matches the display window size of the LCD light valve 7. The edge light lost by Köhler illumination is reflected back through the hollow light guide rod 5 and fully utilized by the projection lens, thereby effectively improving the lighting efficiency to over 85%. At the same time, the lighting light at the edge of the LCD light valve display window is increased, which can effectively improve the uniformity of the lighting. Moreover, the improvement can be at least 5% without significantly increasing the volume of the projector optical system, so that the lighting uniformity is improved to over 50%.

[0043] In this embodiment, the refractive index of the material of the collimating lens 3 is n; the plane of the collimating lens 3 is the incident surface, the tooth surface is the exit surface, and the thickness from the plane to the tooth root of the tooth surface is c; the concentrator 2 is a hollow square cone concentrator, and the exit surface of the concentrator 2 is aligned with the incident surface of the collimating lens 3; the corresponding angle of the aperture designed for the LCD light valve 7 on the projector optical system is θ.

[0044] The exit surface of the hollow square cone concentrator and ≤1.02a. The exit surface of the hollow square cone concentrator And ≤1.02b.

[0045] The following is an explanation of the existing technology:

[0046] Figure 3 This is a typical lighting system diagram that uses lens focusing in the industry. In the figure, 1' is the LED light source, 2' is the condenser (lens), 3' is the collimating lens (mirror), and 7' is the LCD light valve. This type of structure has the same technical conditions (such as the same projection lens, similar volume, etc.). Figure 4 ) in this case, uniformity is slightly better, the heat dissipation of the LCD light valve 7' is slightly better, and product stacking can display a wider variety of appearances. However, due to the slightly higher cost and the extreme difficulty of lens design, many manufacturers do not have the lens R&D and design capabilities, so it will completely fade out of the market starting in 2023. Figure 3 With the technology shown, the lighting efficiency η (e.g., η = luminous flux of the LCD light valve 7' / luminous flux of the LED light source 1', hereinafter the same) ranges from 45% to 65%, depending on the design and manufacturing level. The lighting uniformity γ (e.g., if the LCD light valve 7' is divided into 96*54 equal parts and the number of light traced is 300,000, γ = minimum illumination / maximum illumination, hereinafter the same) ranges from 25% to 40%.

[0047] Figure 4 This is a typical lighting system diagram that uses a light bucket to focus light in the industry. In the figure, 1' is an LED light source, 2' is a concentrator (light bucket), 3' is a collimating lens (Phi lens), and 7' is an LCD light valve. Under the same technical conditions, this type of structure has a higher η' because the uniformity is lower and the LCD light valve 7' is more difficult to dissipate heat. The appearance that can be displayed by product stacking is relatively limited, which has certain cost advantages. Even without optical design capabilities, it does not greatly affect production and shipments. For example, if a serious high-level optical design is 100 points, if you do not have optical design capabilities but refer to similar products, you can still get 60 points. Consumers are not very sensitive to cheap products. Therefore, the products that dominate the industry are such as Figure 4 The light beam lighting technology shown has a lighting efficiency η between 50% and 70%; under the same tracking conditions, the lighting uniformity γ ranges from 20% to 35%.

[0048] See also Figure 5 The prior art shown in the figure, the quantitative parameters of all optical materials are as follows:

[0049]

[0050] The parameters in the table above are from a product currently available on JD.com, model: Zhima Z3 (ZMLD3001). This product features an F#2.8 projection lens. Ray tracing revealed an illumination uniformity γ of 49% and an illumination efficiency η of 80.2%. These indicators represent the highest standards in product design and manufacturing within the industry, resulting in a relatively high-end and leading output brightness among similar products.

[0051] That is to say, using Figure 3-Figure 5 For the simple illumination system of a single LCD projector shown, achieving an η of over 80% and a γ of 50% under the aforementioned (tracking) condition is quite difficult (in reality, 99.99% of products fail to meet this target). This is because, in addition to the inherent contradiction between the parameters γ and η, there are also more practical constraints such as cost, volume, and engineering implementation. Without replacing the collimating lens 3' (e.g., replacing the lens with an aspheric glass lens), the core lighting efficiency loss that can be improved is between the collimating lens 3' and the LCD light valve 7'. See [the following text for details] for details. Figure 5As shown, the specific manifestation is that the edge light w' causes direct loss, and the collimating lens 3' and LCD light valve 7' cannot be installed close together to utilize w' because the fringes of the collimating lens 3' will be imaged by the projection objective lens on the screen, seriously affecting viewing. The technical innovation of the present invention is that by reflecting the edge light w' back through the hollow light guide rod 5, the optical etendue of the illumination light illuminating the LCD light valve 7' is completely unchanged, so w' can be fully utilized by the projection objective lens, improving lighting efficiency, and increasing the illumination light at the edge of the LCD light valve 7' display window, which can effectively improve lighting uniformity.

[0052] by Figure 5 In the embodiment shown, the technical innovation of the present invention can fully utilize the inherent light loss w' (approximately 89.5%-80.2%=9.3%) between the collimating lens 3' and the LCD light valve 7', thereby improving the lighting efficiency by 11.6%. For most common products, since their own lighting efficiency is not high (for example, there are deficiencies in the design and manufacture of the concentrator 2'), the η of most products is between 50% and 60%. After using the device of the present invention, η can almost be increased to more than 85%. In other words, the output brightness of the projector is increased by 140%-170%. Moreover, after using the device of the present invention, the uniformity of illumination can be improved by at least 5% without significantly increasing the volume of the optical system, so that γ is increased to more than 50%.

[0053] See also Figure 6 As shown, these are some innovative technologies disclosed in the industry for simple Köhler illumination. In the figure, 1' is an LED light source, 2' is a concentrator (light hopper), 3' is a collimating lens, 7' is an LCD light valve, and 8' is a light guide rod. People insert a light guide rod 8' (solid or hollow) at the incident end of concentrator 2' in the hope of enhancing and improving the uniformity of illumination. However, this is contrary to basic optical common sense and is fundamentally impossible. This is fundamentally different from the present invention, which inserts a hollow light guide rod 5 between the collimating lens 3 and the LCD light valve 7.

[0054] Finally, it should be noted that the overall development trend of the domestic single-LCD projector market is to meet comprehensive demands such as miniaturization, low cost, and high brightness. According to incomplete statistics, the shipment volume of single-LCD projectors in 2024 will be approximately 39 million units, of which 2-inch to 2.69-inch products are the absolute majority (accounting for nearly 90%), while LCD light valves ≥3.97 inches (including 4.45 inches, 5 inches, 5.5 inches, 5.7 inches, 6.37 inches, etc.) account for less than 5%, and the remaining approximately 5% of the market share is for 3-inch, 3.5-inch and other products. The present invention is aimed at smaller-sized LCD light valves (LCD light valves ≤3.5 inches) and has excellent adaptability in improving lighting efficiency and uniformity. If the LCD light valve size is larger, such as >3.5 inches, the present invention will cause the volume (length) of the optical system to increase significantly, and its practicality is also limited.

[0055] A projector optical system includes the novel Kohler illumination device described in the first and second embodiments. It also includes conventional configurations of an optical system such as a field lens and a projection lens. This is conventional technology for projector optical systems and will not be elaborated on here.

[0056] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0057] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method of the present invention and its core ideas. The above are only preferred implementation methods of the present invention. It should be pointed out that due to the limitations of digital expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of the present invention.

Claims

1. A new Kohler lighting device, characterized in that: It comprises an LED light source (1), a condenser (2), a collimating lens (3), a hollow light guide rod (5) and an LCD light valve (7) which are arranged in sequence according to the direction of light travel; The inner wall of the hollow light guide rod (5) is provided with a reflective film; the incident end of the hollow light guide rod (5) is in contact with the exit surface of the collimating lens (3), and the exit end of the hollow light guide rod (5) is in contact with the incident surface of the LCD light valve (7); The long side of the display window of the LCD light valve (7) is a, the short side is b, the diagonal length is Φ, the long side of the light-transmitting cross section of the hollow light guide rod (5) is ≥a and ≤1.02a; the short side of the light-transmitting cross section of the hollow light guide rod (5) is ≥b and ≤1.02b; The length of the hollow light guide rod (5) is ≥0.1φ.

2. A novel Kohler lighting device according to claim 1, characterized in that: The collimating lens (3) is a Fresnel lens, the refractive index of the material of the collimating lens (3) is n, the plane of the Fresnel lens is the incident surface, the tooth surface is the exit surface, and the thickness from the plane to the tooth root of the tooth surface is c; The condenser (2) is a hollow square cone condenser, and the exit surface of the condenser (2) is in contact with the incident surface of the collimating lens (3); The corresponding angle of the aperture designed for the LCD light valve (7) on the projector optical system is θ; The exit surface of the hollow square cone concentrator and ≤1.02a; The exit surface of the hollow square cone concentrator And ≤1.02b.

3. A new Kohler lighting device, characterized in that: It comprises an LED light source (1), a condenser (2), a collimating lens (3), a thin glass plate (4), a hollow light guide rod (5) and an LCD light valve (7) which are arranged in sequence according to the direction of light travel; The collimating lens (3) is a Fresnel lens, and the exit surface is in contact with the incident surface of the thin glass plate (4); The inner wall of the hollow light guide rod (5) is provided with a reflective film; the incident end of the hollow light guide rod (5) is in contact with the exit surface of the thin glass plate (4), and the exit end of the hollow light guide rod (5) is in contact with the incident surface of the LCD light valve (7); The interior of the hollow light guide rod (5) is filled with a non-gaseous transparent optical medium (6); The long side of the display window of the LCD light valve (7) is a, the short side is b, and the diagonal length is Φ; the refractive index of the transparent optical medium (6) is n1; Then the long side of the light-transmitting cross section of the hollow light guide rod (5) is ≥a and ≤1.02a; the short side of the light-transmitting cross section of the hollow light guide rod (5) is ≥b and ≤1.02b; The optical length of the hollow light-guiding rod (5) in the transparent optical medium (6) is ≥0.1n1Φ.

4. The novel Kohler lighting device according to claim 3, characterized in that: The refractive index of the material of the collimating lens (3) is n; the plane of the collimating lens (3) is the incident surface, the tooth surface is the exit surface, and the thickness from the plane to the tooth root of the tooth surface is c; The condenser (2) is a hollow square cone condenser, and the exit surface of the condenser (2) is in contact with the incident surface of the collimating lens (3); The corresponding angle of the aperture designed for the LCD light valve (7) on the projector optical system is θ; The exit surface of the hollow square cone concentrator and ≤1.02a; The exit surface of the hollow square cone concentrator And ≤1.02b.

5. A projector optical system, characterized in that: The novel Kohler lighting device comprises any one of claims 1 to 4.

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