An optical projection system and projection device

Abstract

This application discloses an optical projection system and projection device. The optical projection system, from the magnification side to the reduction side, includes a first lens, an aperture stop, and a lens group. The lens group includes at least three lenses. The optical power of the lens closest to the aperture stop in the lens group is opposite to that of the first lens, and the optical power of the lens group is positive. The ratio between the total length TL of the optical projection system and the aperture D of the largest lens among all lenses satisfies 1. <TL / D<2.3。

Description

Technical Field

[0001] This application relates to the technical field of optical devices, and more particularly, to an optical projection system and a projection device. Background Art

[0002] With the vigorous development of science and technology, projection technology has become increasingly mature, and the application fields of projection devices have become wider and wider. For example, it is applied to commercial fields such as conference explanations, circuit exhibitions, and promotional activities, educational fields such as school teaching and academic discussions, and home fields such as home theaters. In recent years, Digital Light Processing (DLP) projection devices have become the mainstream technology of current projection devices, and they are better choices among projection display products in terms of lightness, durability, high brightness, high contrast, etc.

[0003] Currently, the optical design in DLP projection devices mainly includes illumination system design and imaging system design. Among them, the quality of the imaging system design directly determines the imaging clarity, picture size, and image quality of picture distortion of the projection device product. Generally speaking, in order to improve the imaging quality of the projection device, a relatively large number of lenses are usually required to be used in combination in the projection device. However, this will lead to an increase in the volume of the projection device. Therefore, how to balance the number of lenses in the projection device and the imaging quality of the projection device has become one of the main research directions in the industry. Summary of the Invention

[0004] An object of this application is to provide a new technical solution for an optical projection system and a projection device.

[0005] According to the first aspect of this application, an optical projection system is provided. The optical projection system sequentially includes from the magnifying side to the reducing side:

[0006] A first lens, an aperture stop, and a lens group;

[0007] The lens group includes at least three lenses;

[0008] The focal power of the lens in the lens group closest to the aperture stop is opposite to the focal power of the first lens, and the focal power of the lens group is positive;

[0009] The ratio of the total length TL of the optical projection system to the aperture D of the largest one of all lenses satisfies 1 < TL / D < 2.3.

[0010] Optionally, the optical projection system satisfies 5.80 mm < effl < 6.60 mm, where effl is the effective focal length of the optical projection system.

[0011] Optionally, the lens group includes a second lens, a third lens, a fourth lens, and a fifth lens sequentially arranged from the magnifying side to the reducing side;

[0012] The optical power of the first lens is negative, and the optical power of the second lens is positive.

[0013] Optionally, the magnifying side of the first lens is convex, and the reducing side is concave; the magnifying side of the second lens is convex; the magnifying side of the third lens is concave, and the reducing side is concave; the magnifying side of the fourth lens is concave, and the reducing side is convex; the magnifying side of the fifth lens is convex, and the reducing side is convex.

[0014] Optionally, the effective focal length f1 of the first lens satisfies -9.48 mm < f1 < -9.08 mm; the effective focal length f2 of the second lens satisfies 4.137 mm < f2 < 4.637 mm; the effective focal length f3 of the third lens satisfies -2.838 mm < f3 < -2.22 mm; the effective focal length f4 of the fourth lens satisfies 6.26 mm < f4 < 6.8 mm, and the effective focal length f5 of the fifth lens satisfies 6.16 mm < f5 < 6.6 mm.

[0015] Optionally, the ratio range of the distance from the first lens to the aperture to the distance from the second lens to the aperture is 1 to 3.

[0016] Optionally, the lens group includes a second lens, a third lens, and a sixth lens sequentially arranged from the magnifying side to the reducing side, and the sixth lens is an aspherical lens; there is an air gap between the second lens and the third lens;

[0017] The optical power of the first lens is negative, and the optical power of the second lens is positive.

[0018] Optionally, the magnifying side of the sixth lens is convex, and the reducing side is convex.

[0019] Optionally, the lens group includes a third lens, a fourth lens, a fifth lens, and a seventh lens sequentially arranged from the magnifying side to the reducing side;

[0020] The optical power of the first lens is positive, and the optical power of the third lens is negative.

[0021] Optionally, the magnifying side of the first lens is convex, and the reducing side is convex; the magnifying side of the third lens is concave, and the reducing side is concave; the magnifying side of the fourth lens is concave, and the reducing side is convex; the magnifying side of the fifth lens is convex, and the reducing side is convex; the magnifying side of the seventh lens is convex.

[0022] Optionally, the effective focal length f7 of the seventh lens satisfies 6.7mm. <f7<8.6mm。

[0023] Optionally, the lens group includes a third lens, a fourth lens, and a sixth lens arranged sequentially from the magnifying side to the reducing side, wherein the sixth lens is an aspherical lens;

[0024] The first lens has a positive optical power, and the third lens has a negative optical power.

[0025] According to a second aspect of this application, a projection device is provided, the projection device comprising the optical projection system as described in the first aspect.

[0026] In the optical projection system provided in this application embodiment, through the optimized configuration of various parameters, it can achieve better imaging effect and smaller size.

[0027] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0029] Figure 1 The diagram shown is an optical structure schematic of an optical projection system according to this application. Figure 1 ;

[0030] Figure 2 The diagram shown is an optical structure schematic of an optical projection system according to this application. Figure 2 ;

[0031] Figure 3 The diagram shown is an optical structure schematic of an optical projection system according to this application. Figure 3 ;

[0032] Figure 4 The diagram shown is an optical structure schematic of an optical projection system according to this application. Figure 4 ;

[0033] Figure 5 The diagram shown is a schematic diagram of the modulation transfer function of Embodiment 1 in an optical projection system of this application;

[0034] Figure 6 The diagram shown is a schematic diagram of the modulation transfer function of Embodiment 2 in an optical projection system of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Aperture; 9. Equivalent prism; 10. Protective glass; 11. Display chip. Detailed Implementation

[0037] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0038] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0039] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0040] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0042] Reference Figures 1-4 As shown, according to one embodiment of this application, an optical projection system is provided, which includes a first lens 1, an aperture 8, and a lens group sequentially from the magnification side to the reduction side; the lens group includes at least three lenses; the optical power of the lens closest to the aperture 8 in the lens group is opposite to that of the first lens 1, and the optical power of the lens group is positive; the ratio between the total length TL of the optical projection system and the aperture D of the largest lens among all lenses satisfies 1. <TL / D<2.3。

[0043] The optical projection system provided in this application embodiment also includes an equivalent prism 9, a protective glass 10, and a display chip 11. More specifically, the equivalent prism 9 is an equivalent bend prism, used to transmit the light emitted or reflected by the display chip 11 into the lens. The protective glass 10 protects the display chip 11 from external contaminants. The display chip 11 can be a digital micromirror device (DMD), a liquid crystal on silicon (LCOS), a liquid crystal display (LCD), etc. It can be understood that the display chip 11 is a laser light source of different wavelengths or other light source capable of emitting light beams.

[0044] The optical projection system provided in this application embodiment is applied to a projection device. The optical projection system includes a reduction side and a magnification side along the light transmission direction. The display chip 11, protective glass 10, equivalent prism 9, lens group, aperture 8, and first lens 1 in the optical projection system are sequentially arranged between the reduction side and the magnification side along the same optical axis. The reduction side is the side where the image source (e.g., the display chip 11) that generates the projected light during the projection process is located, i.e., the image side; the magnification side is the side where the projection surface (e.g., the projection screen) used to display the projected image is located during the projection process, i.e., the object side. The transmission direction of the projected light is from the reduction side to the magnification side. However, in the actual design of the optical projection system, based on the principle of optical path reversibility, the light is simulated from the actual magnification side to the reduction side.

[0045] Specifically, in the actual projection process, the projection light is emitted by the display chip 11, from the shrinking side toward the magnifying side, and passes through the protective glass 10, the equivalent prism 9, the lens group, the aperture 8 and the first lens 1 in sequence, thereby displaying the projected image.

[0046] In this embodiment, the display chip 11, serving as the image source, can be a Digital Micromirror Device (DMD) chip. A DMD consists of many matrix-arranged digital micromirrors. During operation, each micromirror can deflect and lock in both directions, allowing light to be projected in a predetermined direction and oscillate at frequencies of tens of thousands of hertz. The light beam from the illumination source is reflected by the micromirrors into the optical system and imaged on the screen. DMDs offer advantages such as high resolution and no need for digital-to-analog conversion. This embodiment uses a 0.16' DMD with an aspect ratio of 16:9. Specific dimensions could be, for example, 3.456*1.944mm, with a minimum projection ratio of 1.2 and a maximum offset of 100%. It should be noted that the image source size applicable to the imaging optical path architecture in this embodiment is not limited to a 0.16' DMD and 100% offset. The allowed full image source size in this embodiment can be within 5.2mm, and the full field of view within 64°. Of course, the display chip 11 used as the image source can also be a liquid crystal on silicon (LCOS) chip, a liquid crystal display (LCD) panel, or other display elements that can emit light. This application does not limit this.

[0047] In this embodiment, lenses are respectively arranged on both sides of the diaphragm 8, where one side of the two sides is close to the magnification side and the other side is close to the reduction side. Among them, only one lens, that is, the first lens 1, is arranged on the side of the diaphragm 8 close to the magnification side; while a lens group including at least three lenses is arranged on the side of the diaphragm 8 close to the reduction side. Among them, the optical power of the lens closest to the diaphragm 8 in the lens group is opposite to the optical power of the first lens 1, and the optical power of the lens group is positive. For example, when the optical power of the first lens 1 is positive, the optical power of the lens closest to the diaphragm 8 in the lens group is negative; for example, when the optical power of the first lens 1 is negative, the optical power of the lens closest to the diaphragm 8 in the lens group is positive. In the optical projection system of the embodiment of the present application, an inverse telephoto lens group scheme is adopted, and the optical power distribution follows the negative-positive distribution method, and the optical power of the entire optical projection system is balanced, meeting the requirements of the projection system for the image value. And it helps to achieve imaging quality with low distortion and high image resolution.

[0048] In addition, in the optical projection system provided in the embodiment of the present application, by setting the ratio between the total length TL of the optical projection system and the aperture D of the largest one of all the lenses to satisfy 1<TL / D<2.3, this can ensure the imaging picture quality while making the structure of the optical projection system compact, thereby ensuring the small volume size of the optical projection system to a certain extent and making the optical projection system easy to carry and use. That is, in the optical projection system provided in the embodiment of the present application, the imaging effect of the optical projection system can be improved while reducing the volume of the optical projection system. The optical projection system provided in the embodiment of the present application has small projection image distortion, high relative illumination and high MTF modulation function.

[0049] In one embodiment, the optical projection system satisfies 5.80mm<effl<6.60mm, where effl is the effective focal length of the optical projection system.

[0050] In this specific example, by setting the value of the effective focal length effl of the optical projection system to 5.80mm<effl<6.60mm, it is possible to ensure the imaging picture quality while making the structure of the optical projection system compact, thereby ensuring the small volume size of the optical projection system to a certain extent and making the optical projection system easy to carry and use.

[0051] Refer to Figure 1 As shown, in one embodiment, the lens group includes a second lens 2, a third lens 3, a fourth lens 4 and a fifth lens 5 arranged in sequence from the magnification side to the reduction side; the optical power of the first lens 1 is negative, and the optical power of the second lens 2 is positive.

[0052] In this specific example, the optical projection system employs five spherical mirrors, which are arranged in sequence from the magnifying side to the reducing side as the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5. Among them, the first lens 1 is located on the magnifying side close to the aperture stop 8, and the optical power of the first lens 1 is negative; the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 are located on the reducing side close to the aperture stop 8. Moreover, the second lens 2 is the closest to the aperture stop 8 among the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5, and the optical power of the second lens 2 is positive; and the optical power of the lens group composed of the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 is positive. The lens arrangement design in this embodiment ensures a relatively small volume size of the optical projection system while ensuring a relatively low cost.

[0053] In one embodiment, the magnifying side surface of the first lens 1 is convex, and the reducing side surface is concave; the magnifying side surface of the second lens 2 is convex; the magnifying side surface of the third lens 3 is concave, and the reducing side surface is concave; the magnifying side surface of the fourth lens 4 is concave, and the reducing side surface is convex; the magnifying side surface of the fifth lens 5 is convex, and the reducing side surface is convex.

[0054] In this specific example, the first lens 1 is a convex-concave lens, the magnifying side surface of the second lens 2 is convex, the third lens 3 is a double-concave lens, the fourth lens 4 is a convex-concave lens, and the fifth lens 5 is a double-convex lens. Through the above surface shape structure design of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5, the entire optical projection system meets the requirements of a relatively high image value and the ability of light convergence.

[0055] In one embodiment, the effective focal length f1 of the first lens 1 satisfies -9.48 mm < f1 < -9.08 mm; the effective focal length f2 of the second lens 2 satisfies 4.137 mm < f2 < 4.637 mm; the effective focal length f3 of the third lens 3 satisfies -2.838 mm < f3 < -2.22 mm; the effective focal length f4 of the fourth lens 4 satisfies 6.26 mm < f4 < 6.8 mm, and the effective focal length f5 of the fifth lens 5 satisfies 6.16 mm < f5 < 6.6 mm. Moreover, the ratio range of the distance from the first lens 1 to the aperture stop 8 to the distance from the second lens 2 to the aperture stop 8 is 1 to 3.

[0056] In this specific example, by limiting the effective focal length f1 of the first lens 1, the effective focal length f2 of the second lens 2, the effective focal length f3 of the third lens 3, the effective focal length f4 of the fourth lens 4, and the effective focal length f5 of the fifth lens 5; and by limiting the range of the ratio of the distance from the first lens 1 to the aperture stop 8 to the distance from the second lens 2 to the aperture stop 8, the optical design parameters can be optimized. While meeting the imaging quality requirements, the radial dimension of the optical projection system can be effectively reduced, which is beneficial for the thinner and smaller design of the optical projection system.

[0057] Reference Figure 2 As shown, in one embodiment, the lens group includes a second lens 2, a third lens 3, and a sixth lens 6 arranged sequentially from the magnifying side to the reducing side, wherein the sixth lens 6 is an aspherical lens; there is an air gap between the second lens 2 and the third lens 3; the optical power of the first lens 1 is negative, and the optical power of the second lens 2 is positive.

[0058] In this specific example, compared to the previous embodiment, an aspherical lens, namely the sixth lens 6, replaces the two spherical lenses closest to the equivalent prism 9. Because the aspherical lens has a higher ability to correct phase aberrations, it can replace two lenses with one, thereby further reducing the size of the optical projection system. Furthermore, the magnifying side and the reducing side of the sixth lens 6 are both convex.

[0059] Reference Figure 3 As shown, in one embodiment, the lens group includes a third lens 3, a fourth lens 4, a fifth lens 5, and a seventh lens 7 arranged sequentially from the magnifying side to the reducing side; the optical power of the first lens 1 is positive, and the optical power of the third lens 3 is negative.

[0060] In this specific example, the optical projection system employs five spherical mirrors, arranged sequentially from the magnification side to the reduction side as a first lens 1, a third lens 3, a fourth lens 4, a fifth lens 5, and a seventh lens 7. The first lens 1 is located near the magnification side of the aperture stop 8, and its optical power is positive. The third lens 3, fourth lens 4, fifth lens 5, and seventh lens 7 are located near the reduction side of the aperture stop 8. Among these, the third lens 3 is the closest to the aperture stop 8, and its optical power is negative. The lens group consisting of the third lens 3, fourth lens 4, fifth lens 5, and seventh lens 7 has positive optical power. This lens arrangement design in this embodiment ensures both a small overall size and low cost for the optical projection system.

[0061] In one embodiment, the magnifying side of the first lens 1 is convex, and the reducing side is convex; the magnifying side of the third lens 3 is concave, and the reducing side is concave; the magnifying side of the fourth lens 4 is concave, and the reducing side is convex; the magnifying side of the fifth lens 5 is convex, and the reducing side is convex; the magnifying side of the seventh lens 7 is convex.

[0062] In this specific example, the first lens 1 is a biconvex lens, the third lens 3 is a biconcave lens, the fourth lens 4 is a convex-concave lens, and the fifth lens 5 is a biconvex lens; the magnifying side of the seventh lens 7 is convex. Through the above surface structure design of the first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5 and the seventh lens 7, the entire optical projection system meets the higher image value requirements and light converging ability.

[0063] In one embodiment, the effective focal length f1 of the first lens 1 satisfies 9.48 mm < f1 < 9.08 mm; the effective focal length f3 of the third lens 3 satisfies -2.838 mm < f3 < -2.22 mm; the effective focal length f4 of the fourth lens 4 satisfies 6.26 mm < f4 < 6.8 mm, the effective focal length f5 of the fifth lens 5 satisfies 6.16 mm < f5 < 6.6 mm, and the effective focal length f7 of the seventh lens 7 satisfies 6.7 mm < f7 < 8.6 mm.

[0064] In this specific example, by limiting the effective focal length f1 of the first lens 1, the effective focal length f3 of the third lens 3, the effective focal length f4 of the fourth lens 4, the effective focal length f5 of the fifth lens 5, and the effective focal length f7 of the seventh lens 7; the optical design indicators can be optimized, while meeting the imaging quality, effectively reducing the radial size of the optical projection system, which is beneficial to the thin and light design and miniaturization design of the optical projection system.

[0065] Refer to Figure 4 As shown, in one embodiment, the lens group includes a third lens 3, a fourth lens 4, and a sixth lens 6 arranged in sequence from the magnifying side to the reducing side, and the sixth lens 6 is an aspherical lens; the optical power of the first lens 1 is positive, and the optical power of the third lens 3 is negative.

[0066] In this specific example, compared with the previous embodiment, an aspherical lens, that is, the sixth lens 6, is used to replace two spherical lenses closest to the equivalent prism 9. Since the aspherical lens has a higher ability to correct aberrations, it can replace two with one, thereby further reducing the volume of the optical projection system. Further, the magnifying side of the sixth lens 6 is convex, and the reducing side is convex.

[0067] The optical projection system provided in this application embodiment has low image distortion, high relative illumination, and high MTF modulation function; through the optimized configuration of the above parameters, it can achieve a high image clarity imaging effect in various fields of view.

[0068] According to another embodiment of this application, a projection device is provided, which includes the optical projection system described above. The projection device may be, for example, a projector, or an illumination engine.

[0069] Example 1:

[0070] Reference Figure 1 As shown, from the magnification side to the reduction side, the optical projection system is sequentially equipped with a first lens 1, an aperture 8, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, an equivalent prism 9, a protective glass 10, and a display chip 11; the optical projection system satisfies an effective focal length effl = 6.39 mm, and the total optical length TL of the optical projection system is 8.7 mm. The design objectives of the 023'DMD are as follows:

[0071] The projection ratio is 1.85, the projection distance is 609mm, the offset is 0%, the TV distortion is <0.5%, the full field of view MTF is >0.5@96lp / mm, the telecentricity is <1.5°, the chromatic difference is <0.5pixel, and the F# is 1.71.

[0072] The optical projection system in this embodiment includes five spherical lenses; wherein, the magnifying side S1 of the first lens 1 is convex and the reducing side S2 is concave; the magnifying side S3 of the second lens 2 is convex and the reducing side S4 is convex; the magnifying side S5 of the third lens 3 is concave and the reducing side S6 is concave; the magnifying side S7 of the fourth lens 4 is concave and the reducing side S8 is convex; and the magnifying side S9 of the fifth lens 5 is convex and the reducing side S10 is convex.

[0073] The parameters involved in Example 1 are shown in Table 1 below:

[0074] Table 1

[0075]

[0076] A schematic diagram of the modulation transfer function of the optical projection system shown in Example 1 is as follows: Figure 5 As shown in the figure, the MTF value of each field of view is higher than 0.56, indicating that the image clarity after imaging by this system is very high in each field of view, and other performance also meets the design requirements.

[0077] Example 2:

[0078] Reference Figure 4As shown, from the magnification side to the reduction side, the optical projection system sequentially includes a first lens 1, an aperture 8, a third lens 3, a fourth lens 4, a sixth lens 6, an equivalent prism 9, a protective glass 10, and a display chip 11; the optical projection system satisfies an effective focal length effl = 6.45mm, and the total optical length TL of the optical projection system is 8.6mm. The design objectives of the 023'DMD are as follows:

[0079] The projection ratio is 1.85, the projection distance is 609mm, the offset is 0%, the TV distortion is <0.5%, the full field of view MTF is >0.5@96lp / mm, the telecentricity is <1.5°, the chromatic difference is <0.5pixel, and the F# is 1.71.

[0080] The optical projection system in this embodiment includes three spherical lenses and one aspherical lens; wherein, the magnifying side S1 of the first lens 1 is convex and the reducing side S2 is convex; the magnifying side S3 of the third lens 3 is concave and the reducing side S4 is concave; the magnifying side S5 of the fourth lens 4 is concave and the reducing side S6 is convex; and the magnifying side S7 of the sixth lens 6 is convex and the reducing side S8 is convex.

[0081] The parameters involved in Example 2 are shown in Table 2 below:

[0082]

[0083] A schematic diagram of the modulation transfer function of the optical projection system shown in Example 2 is as follows: Figure 6 As shown in the figure, the MTF value of each field of view is higher than 0.55, indicating that the image clarity after imaging by this system is very high in each field of view, and other performance also meets the design requirements.

[0084] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An optical projection system, characterized in that, From the magnification side to the reduction side, it successively includes: A first lens (1), an aperture stop (8), and a lens group; The lens group includes four lenses, namely a second lens (2), a third lens (3), a fourth lens (4), and a fifth lens (5) successively arranged from the magnification side to the reduction side; the optical power of the first lens (1) is negative, and the optical power of the second lens (2) is positive; the optical power of the third lens (3) is negative, and the optical power of the fourth lens (4) is positive; the optical power of the fifth lens (5) is positive; The optical power of the lens closest to the aperture stop (8) in the lens group is opposite to the optical power of the first lens (1), and the optical power of the lens group is positive; The ratio of the total length TL of the optical projection system to the aperture D of the largest one of all lenses satisfies 1 < TL / D < 2.3; the effective focal length f1 of the first lens (1) satisfies -9.48 mm < f1 < -9.08 mm; the effective focal length f2 of the second lens (2) satisfies 4.137 mm < f2 < 4.637 mm.

2. The optical projection system according to claim 1, characterized in that, The optical projection system satisfies 5.80 mm < effl < 6.60 mm, where effl is the effective focal length of the optical projection system.

3. The optical projection system according to claim 1, characterized in that, The ratio range of the distance from the first lens (1) to the aperture stop (8) to the distance from the second lens (2) to the aperture stop (8) is 1 to 3.

4. An optical projection system, characterized in that, From the magnification side to the reduction side, it successively includes: A first lens (1), an aperture stop (8), and a lens group; The lens group includes three lenses, namely a second lens (2), a third lens (3), and a sixth lens (6) successively arranged from the magnification side to the reduction side. The sixth lens (6) is an aspherical lens; there is an air gap between the second lens (2) and the third lens (3); the optical power of the first lens (1) is negative, and the optical power of the second lens (2) is positive; the optical power of the third lens (3) is negative, and the optical power of the sixth lens (6) is positive; The optical power of the lens closest to the aperture stop (8) in the lens group is opposite to the optical power of the first lens (1), and the optical power of the lens group is positive; The ratio of the total length TL of the optical projection system to the aperture D of the largest one of all lenses satisfies 1 < TL / D < 2.3; the optical projection system satisfies 5.80 mm < effl < 6.60 mm, where effl is the effective focal length of the optical projection system.

5. An optical projection system, characterized in that, From the magnification side to the reduction side, it successively includes: A first lens (1), an aperture stop (8), and a lens group; The lens group includes four lenses, namely a third lens (3), a fourth lens (4), a fifth lens (5), and a seventh lens (7) successively arranged from the magnification side to the reduction side; the optical power of the first lens (1) is positive, the optical power of the third lens (3) is negative; the optical power of the fourth lens (4) is positive; the optical power of the fifth lens (5) is positive; the optical power of the seventh lens (7) is positive; The focal power of the lens closest to the aperture (8) in the lens group is opposite to that of the first lens (1), and the focal power of the lens group is positive; The ratio of the total length TL of the optical projection system to the aperture D of the largest lens among all the lenses satisfies 1 < TL / D < 2.3; the effective focal length f7 of the seventh lens (7) satisfies 6.7 mm < f7 < 8.6 mm.

6. The optical projection system according to claim 5, characterized in that, The magnifying side of the seventh lens (7) is convex.

7. The optical projection system according to claim 5, characterized in that, The optical projection system satisfies 5.80 mm < effl < 6.60 mm, where effl is the effective focal length of the optical projection system.

8. An optical projection system, characterized in that, In sequence from the magnifying side to the reducing side, it includes: A first lens (1), an aperture (8), and a lens group; The lens group includes three lenses, namely a third lens (3), a fourth lens (4), and a sixth lens (6) arranged in sequence from the magnifying side to the reducing side. The sixth lens (6) is an aspherical lens; the focal power of the first lens (1) is positive, the focal power of the third lens (3) is negative; the focal power of the fourth lens (4) is positive; the focal power of the sixth lens (6) is positive; The focal power of the lens closest to the aperture (8) in the lens group is opposite to that of the first lens (1), and the focal power of the lens group is positive; The ratio of the total length TL of the optical projection system to the aperture D of the largest lens among all the lenses satisfies 1 < TL / D < 2.3; the optical projection system satisfies 5.80 mm < effl < 6.60 mm, where effl is the effective focal length of the optical projection system.

9. The optical projection system according to claim 4 or 8, characterized in that, The magnifying side of the sixth lens (6) is convex and the reducing side is convex.

10. A projection device, characterized in that, The projection device includes the optical projection system according to any one of claims 1-9.

Images