Projection lens and electronic equipment

Abstract

The present application discloses a projection lens and an electronic device. The projection lens includes, in order along the direction of incident transmission of an image beam: a first lens group, a second lens group, and an aspheric reflector, wherein the first lens group, the second lens group, and the aspheric reflector are located on the same optical axis, the first lens group has a positive optical power, the second lens group has a positive optical power, and the aspheric reflector has a negative optical power; a first air gap exists between the first lens group and the second lens group, the first air gap ranges from 30 mm to 45 mm, and the first air gap accounts for 12% to 17% of the total optical length of the projection lens.

Description

Technical Field

[0001] The present application relates to the field of projection technology, and more specifically, to a projection lens and an electronic device. Background Art

[0002] In recent years, the application of projection technology based on digital display chips has been rapidly increasing, and ultra-short-throw projection lenses have attracted increasing market attention. Compared to ordinary projection lenses, ultra-short-throw projection lenses can project a large image at a short distance, significantly saving users' space while preventing other obstacles from obstructing the projected image.

[0003] To achieve higher resolution in projection lenses, the number of lens groups is typically increased. Existing projection lenses, in order to achieve a smaller device size, often incorporate more aspherical lenses to manipulate the optical path. However, this increases costs and makes lens assembly more difficult. Therefore, balancing optical image quality with the size of projection lenses has become a key focus in projection lens product research. Summary of the Invention

[0004] One purpose of this application is to provide a new technical solution for projection lenses and electronic equipment.

[0005] According to a first aspect of an embodiment of the present application, a projection lens is provided. The projection lens includes, in order along the direction of incident transmission of an image beam: a first lens group, a second lens group, and an aspheric reflector, wherein the first lens group, the second lens group, and the aspheric reflector are located on the same optical axis, the first lens group has a positive optical power, the second lens group has a negative optical power, and the aspheric reflector has a negative optical power;

[0006] There is a first air gap between the first lens group and the second lens group. The first air gap ranges from 30 mm to 45 mm and accounts for 12% to 17% of the total optical length of the projection lens.

[0007] Optionally, there is a second air gap between the second lens group and the aspheric reflector, the second air gap ranges from 95 mm to 105 mm, and the second air gap accounts for 41% to 45% of the total optical length of the projection lens.

[0008] Optionally, along the direction of incident transmission of the image light beam, the second lens group includes a positive lens group and a negative lens group, the positive lens group includes at least one lens with positive optical power, and the negative lens group includes at least one lens with negative optical power.

[0009] Optionally, the optical focal length of the positive lens group ranges from 0.018 to 0.038, and the optical focal length of the negative lens group ranges from -0.068 to -0.048.

[0010] Optionally, along the direction of incident transmission of the image light beam, the second lens group includes a fourth lens, a third lens, a second lens and a first lens, and the order of the optical focal lengths of the lenses in the second lens group is: positive, positive, negative, negative.

[0011] Optionally, the fourth lens and the first lens are both aspherical lenses, and the third lens and the second lens are both spherical lenses.

[0012] Optionally, the first lens group includes an aperture, a first cemented lens and a second cemented lens, the first cemented lens and the second cemented lens are located on both sides of the aperture, and the first cemented lens is closer to the second lens group than the second cemented lens.

[0013] Optionally, along the direction of incident transmission of the image light beam, the first cemented lens includes a sixth lens and a fifth lens, the optical focal length of the sixth lens is positive, the optical focal length of the fifth lens is negative, and the refractive index of the sixth lens is higher than the refractive index of the fifth lens.

[0014] Optionally, along the direction of incident transmission of the image light beam, the second cemented lens includes an eighth lens and a seventh lens, the optical focal length of the eighth lens is negative, the optical focal length of the seventh lens is positive, and the refractive index of the seventh lens is lower than the refractive index of the eighth lens.

[0015] Optionally, the refractive index of the seventh lens is in the range of 1.48 to 1.55, and the refractive index of the eighth lens is in the range of 1.82 to 1.92.

[0016] Optionally, in the first lens group, there is a third air gap between adjacent lenses, and the third air gap range is less than 1 mm and greater than or equal to 0.1 mm.

[0017] Optionally, along the direction of incident transmission of the image light beam, the first lens group includes a twelfth lens, an eleventh lens, a tenth lens, a ninth lens, an eighth lens, a seventh lens, a sixth lens and a fifth lens, and the order of the optical focal lengths of the lenses in the first lens group is: positive, positive, negative, positive, negative, positive, positive, negative.

[0018] Optionally, the eleventh lens and the tenth lens are cemented together to form a third cemented lens.

[0019] Optionally, the ninth lens is an aspherical lens, and the twelfth lens, the eleventh lens, the tenth lens, the eighth lens, the seventh lens, the sixth lens and the fifth lens are all spherical lenses.

[0020] Optionally, after the image beam passes through the first lens group and the second lens group, a first image is formed between the second lens group and the aspheric reflector, and the aspheric reflector reflects the first image to the projection screen to form a projection image, and the width of the projection image is c1;

[0021] In the width direction of the projection screen, the distance between the projection screen and the optical axis is c2, wherein the range of c2 / c1 is 38%-42%.

[0022] In a second aspect, an electronic device is provided, comprising the projection lens as described in the first aspect.

[0023] In an embodiment of the present application, a projection lens is provided, wherein a first lens group, a second lens group, and an aspheric reflector of the projection lens are used to limit the air gap between the first lens group and the second lens group. While ensuring the imaging quality of the projection lens, the overall volume of the projection lens is reduced, making the structure of the projection lens more lightweight.

[0024] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0026] Figure 1 Shown is a structural diagram of the projection lens of this application.

[0027] Figure 2 Shown is the optical path diagram of the projection lens of this application.

[0028] Figure 3 Shown is a partial structural optical path of the projection lens of this application Figure 1 .

[0029] Figure 4 Shown is a partial structural optical path of the projection lens of this application Figure 2 .

[0030] Figure 5 Shown is a partial structural optical path of the projection lens of this application Figure 3 .

[0031] Figure 6 Shown is the modulation transfer function diagram of the projection lens of this application.

[0032] Figure 7 Shown is a relative illumination diagram of the projection lens of this application.

[0033] Figure 8 Shown is the distortion diagram of the projection lens of this application.

[0034] Figure 9 Shown is a schematic diagram of the use of the projection lens of this application.

[0035] Description of reference numerals:

[0036] 30. First lens group; 40. Second lens group; 41. Positive lens group; 42. Negative lens group;

[0037] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Tenth lens; 11. Eleventh lens; 12. Twelfth lens; 13. Aspheric reflector; 14. Galvanometer; 15. Prism; 16. Flat glass; 17. Image source. DETAILED DESCRIPTION

[0038] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0039] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0040] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0041] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0042] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0043] The present application provides a projection lens. Figure 1-Figure 2 As shown, the projection lens includes, in order along the direction of incident transmission of the image light beam: a first lens group 30, a second lens group 40, and an aspheric reflector 13. The first lens group 30, the second lens group 40, and the aspheric reflector 13 are on the same optical axis. The optical power of the first lens group 30 is positive, the optical power of the second lens group 40 is negative, and the optical power of the aspheric reflector 13 is negative.

[0044] There is a first air gap between the first lens group 30 and the second lens group 40 . The first air gap ranges from 30 mm to 45 mm and accounts for 12% to 17% of the total optical length of the projection lens.

[0045] In this embodiment, reference Figure 1 and Figure 2 As shown, along the direction of incident transmission of the image light beam, the projection lens includes an image source 17 , a flat glass 16 , a prism 15 , a galvanometer mirror 14 , a first lens group 30 , a second lens group 40 and an aspherical reflector 13 .

[0046] In the embodiment of the present application, the image source 17 may utilize a digital micromirror device (DMD) chip. The DMD is composed of many digital micromirrors arranged in a matrix. During operation, each micromirror can be deflected and locked in both positive and negative directions, thereby projecting light in a predetermined direction and oscillating at a frequency of tens of thousands of hertz. The light beam from the illumination light source is reflected by the micromirrors and then enters the optical system to be imaged on the screen. The DMD has the advantages of high resolution and no need for digital-to-analog conversion of the signal. This embodiment uses a 0.33-inch DMD chip. Of course, the image source 17 may also utilize a liquid crystal on silicon (LCOS) chip or other display element that can be used to emit light, and this application does not impose any restrictions on this.

[0047] In this embodiment, when the image beam is directed to the first lens group 30, the first lens group 30 corrects the image beam and directs the corrected image beam to the second lens group 40; when the image beam is directed to the second lens group 40, the second lens group 40 is used to correct the image beam and transmit the image beam to the aspheric reflector 13, and the first imaging is performed between the aspheric reflector 13 and the second lens group 40. The aspheric reflector 13 reflects the first imaging to the projection screen to form a second imaging. For example, the projection screen can be a wall or a desktop. Figure 3 As shown, A shows the first imaging surface.

[0048] In this embodiment, the optical focal length of the first lens group 30 is positive, the optical focal length of the second lens group 40 is negative, and the optical focal length of the aspheric reflector 13 is negative. The optical focal length of the first lens group 30, the optical focal length of the second lens group 40, and the optical focal length of the aspheric reflector 13 are limited to balance the overall optical focal length of the projection lens, so that the projection lens can better correct aberrations and improve imaging quality.

[0049] In this embodiment, there is a first air gap between the first lens group 30 and the second lens group 40. The first air gap ranges from 30 mm to 45 mm and accounts for 12% to 17% of the total optical length of the projection lens.

[0050] Specifically, based on the principle of reversible optical paths, during normal projection, the image beam sequentially travels through the first lens group 30, the second lens group 40, and the aspheric reflector 13, ultimately forming an image on the projection screen. During the optical path simulation, the light actually travels from the aspheric reflector 13 through the second lens group 40, the first lens group 30, and the image source 17.

[0051] Reference Figure 2 , the light emitted from the second lens group 40 is transmitted to the first lens group 30, and the optical power of the first lens group 30 is positive, and the light emitted from the second lens group 40 begins to converge. If the above-mentioned first air gap exists between the first lens group 30 and the second lens group 40, the lens diameter of the lens closest to the second lens group 40 in the first lens group 30 will be smaller, so that the overall diameter of the first lens group 30 will be smaller, and the volume of the projection lens will be more compact.

[0052] In this embodiment, the air gap between the first lens group 30 and the second lens group 40 is limited to 30 mm to 45 mm. If the air gap between the first lens group 30 and the second lens group 40 is too small, the purpose of reducing the diameter of the lenses in the first lens group 30 cannot be achieved. If the air gap between the first lens group 30 and the second lens group 40 is too large, the purpose of reducing the overall volume of the projection lens cannot be achieved.

[0053] Therefore, in this embodiment, the air gap between the first lens group 30 and the second lens group 40 is limited to this range. While ensuring the imaging quality of the projection lens, the overall volume of the projection lens is reduced, making the structure of the projection lens lighter.

[0054] In one embodiment, referring to Figure 1 and Figure 2 There is a second air gap between the second lens group 40 and the aspheric reflector 13. The second air gap ranges from 95 mm to 105 mm, and the second air gap accounts for 41% to 45% of the total optical length of the projection lens.

[0055] In this embodiment, a second air gap exists between the second lens group 40 and the aspheric reflector 13 , that is, a second air gap exists between the lens in the second lens group 40 closest to the aspheric reflector 13 and the aspheric reflector 13 .

[0056] In this embodiment, the air gap between the lens closest to the aspheric reflector 13 and the aspheric reflector 13 is limited to this range, so that there is enough air gap between the second lens group 40 and the aspheric reflector 13 to ensure that light can converge at a point between the second lens group 40 and the aspheric reflector 13 to form the first imaging.

[0057] If the air gap between the second lens group 40 and the aspheric reflector 13 is small, the first imaging cannot be formed between the second lens group 40 and the aspheric reflector 13; if the air gap between the second lens group 40 and the aspheric reflector 13 is large, it is not conducive to the miniaturization design of the projection lens.

[0058] In addition, in the second lens group 40, the lens closest to the aspheric reflector 13 is an aspheric lens. The function of the aspheric lens is to correct the aberrations of different fields of view. It requires sufficient air space between the adjacent lenses to produce the correction effect. The second air space meets the interval for the aspheric lens to correct the field aberrations.

[0059] In one embodiment, referring to Figure 1 and Figure 2 Along the direction of incident transmission of the image light beam, the second lens group 40 includes a positive lens group 41 and a negative lens group 42, the positive lens group 41 includes at least one lens with positive optical power, and the negative lens group 42 includes at least one lens with negative optical power.

[0060] In this embodiment, the positive lens group 41 and the negative lens group 42 of the second lens group 40 are arranged separately, and there will be no staggered placement of lenses with positive optical power and lenses with negative optical power, which is beneficial to reducing the tolerance sensitivity of the projection lens.

[0061] Specifically, the light emitted from the first lens group 30 is first transmitted through the positive lens group 41. Since the optical focal length of the lenses in the positive lens group 41 is positive, the deflection direction of the light by each lens with positive optical focal length is consistent. The light passing through the positive lens group 41 is deflected in one direction.

[0062] The light emitted from the positive lens group 41 enters the negative lens group 42 for transmission. Since the optical focal length of the lenses in the negative lens group 42 is negative, the deflection direction of the light by each lens with negative optical focal length is consistent. The light passing through the negative lens group 42 is deflected in another direction.

[0063] Therefore, the light emitted from the first lens group 30 enters the second lens group 40, and the light of each field of view is first transmitted as a whole along one direction, and then transmitted to the lens with negative optical focal length adjacent to the positive lens group 41. At this time, the light of each field of view enters the negative lens group 42. Since the effect of the negative lens group 42 on the light is completely different from the deflection direction of the light by the positive lens group 41, the light of each field of view will be transmitted as a whole along another direction.

[0064] In the present application, the optical focal lengths of the lenses in the second lens group 40 are rationally distributed, which greatly reduces the tolerance sensitivity. While ensuring the imaging quality, the tolerance sensitivity is reduced, which reduces the difficulty of assembling the projection lens. Specifically, since the lenses in the positive lens group 41 have the same deflection direction for light, during the installation process, even if there is a slight deviation in the installation position of the lenses in the positive lens group 41, the transmission of light in the positive lens group 41 will not change due to the change in the installation position of the lenses, that is, the final imaging effect will not be affected by the change in the installation position of the lenses. Since the lenses in the negative lens group 42 have the same deflection direction for light, during the installation process, even if there is a slight deviation in the installation position of the lenses in the negative lens group 42, the transmission of light in the negative lens group 42 will not change due to the change in the installation position of the lenses, that is, the final imaging effect will not be affected by the change in the installation position of the lenses.

[0065] In the prior art, lenses with positive optical power and lenses with negative optical power are arranged alternately in the lens group. When light is transmitted in the lens group, the transmission direction of the light is constantly changing. At this time, there is a slight deviation in the installation position of the lenses in the lens group, which has a great impact on the final imaging effect, resulting in poor imaging effect.

[0066] Therefore, compared with the prior art, the second lens group 40 of the present application includes a positive lens group 41 and a negative lens group 42, wherein the positive lens group 41 and the negative lens group 42 are arranged separately, and there will be no situation where lenses with positive optical power and lenses with negative optical power are placed alternately, which is beneficial to reducing the tolerance sensitivity of the projection lens.

[0067] In one embodiment, the optical focal length of the positive lens group 41 ranges from 0.018 to 0.038, and the optical focal length of the negative lens group 42 ranges from -0.068 to -0.048.

[0068] In this embodiment, the optical focal length of the negative lens group 42 and the optical focal length of the positive lens group 41 in the second lens group 40 are limited. The overall optical focal length of the negative lens group 42 is negative, and the overall optical focal length of the positive lens group 41 is positive. In addition, the absolute value of the optical focal length of the negative lens group 42 is greater than the absolute value of the optical focal length of the positive lens group 41, so that the overall optical focal length of the second lens group 40 is negative.

[0069] In addition, in this embodiment, the optical focal length of the negative lens group 42 is limited to this range, the optical focal length of the positive lens group 41 is limited to this range, and the difference between the absolute value of the optical focal length of the negative lens group 42 and the optical focal length of the positive lens group 41 is in the range of 0.01-0.05. The second lens group 40 can correct the aberration well.

[0070] In one embodiment, referring to Figure 1 and Figure 2 Along the direction of incident transmission of the image light beam, the second lens group 40 includes a fourth lens 4, a third lens 3, a second lens 2 and a first lens 1. The order of the optical focal lengths of the lenses in the second lens group 40 is: positive, positive, negative, negative.

[0071] In this embodiment, the second lens group 40 includes four lenses, of which the first lens 1 and the second lens group 40 form a negative lens group 42, and the third lens 3 and the fourth lens 4 form a positive lens group 41. Along the direction of incident transmission of the image beam, the fourth lens 4 and the third lens 3 converge the light, while the second lens 2 and the first lens 1 diverge the light, which is then transmitted to the aspheric reflector 13. The aspheric reflector 13 projects the light onto the screen, enabling the projection lens to project a large image from a short distance.

[0072] Furthermore, the arrangement of the optical powers of the lenses in the second lens group 40 helps reduce the tolerance sensitivity of the projection lens and improve the imaging quality of the projection lens. Furthermore, this embodiment limits the number of lenses in the second lens group 40 and the optical powers of each lens to ensure imaging quality.

[0073] In an optional embodiment, in the second lens group 40, the lens closest to the aspheric reflector 13 is the first lens 1, and the first surface and the second surface of the first lens 1 are both concave surfaces. Figure 2 、 Figure 3 、 Figure 4 and Figure 5 As shown, the first lens 1 diverges the light L1 in the central field of view and converges the light L2 in the peripheral field of view. Therefore, the first lens 1 can correct aberrations in different fields of view. For example, the first lens 1 mainly corrects aberrations in large fields of view and image distortion.

[0074] In one embodiment, the fourth lens 4 and the first lens 1 are both aspherical lenses, and the third lens 3 and the second lens 2 are both spherical lenses.

[0075] In this embodiment, in the second lens group 40, the first lens 1 closest to the aspheric reflector 13 is an aspheric lens, and the fourth lens 4 farthest from the aspheric reflector 13 is also an aspheric lens. Specifically, the first and second surfaces of the first lens 1 are both concave, and the first lens 1 is a biconcave lens. The first and second surfaces of the fourth lens 4 are both convex, and the fourth lens 4 is a biconvex lens. In this embodiment, the aspheric biconcave lens and the aspheric biconvex lens are used to correct aberrations and improve imaging quality.

[0076] In one embodiment, referring to Figure 1 and Figure 2 The first lens group 30 includes an aperture, a first cemented lens and a second cemented lens, the first cemented lens and the second cemented lens are located on both sides of the aperture, and the first cemented lens is closer to the second lens group 40 than the second cemented lens.

[0077] In this embodiment, first lens group 30 includes two cemented lens groups, one located on either side of the aperture. The combination of these two cemented lens groups effectively corrects paraxial image aberrations such as spherical aberration, coma, and chromatic aberration. Furthermore, the combination of these two cemented lens groups allows light to enter first lens group 30 in a converging manner. In a specific embodiment, the first cemented lens allows light to enter first lens group 30 in a converging manner, while the second cemented lens eliminates chromatic aberration.

[0078] In one embodiment, referring to Figure 1 and Figure 2 , along the direction of incident transmission of the image light beam, the first cemented lens includes a sixth lens 6 and a fifth lens 5, the optical focal length of the sixth lens 6 is positive, the optical focal length of the fifth lens 5 is negative, and the refractive index of the sixth lens 6 is higher than the refractive index of the fifth lens 5.

[0079] In this embodiment, the refractive index of the positive-power sixth lens element 6 in the first cemented lens is higher than the refractive index of the negative-power fifth lens element 5, resulting in a positive overall power for the first cemented lens, which converges light. Therefore, light emitted from the second lens group 40 first passes through the first cemented lens element before entering the first lens group 30, allowing the light emitted from the second lens group 40 to enter the first lens group 30 in a converged manner.

[0080] Furthermore, because the first and second cemented lenses are located on either side of the aperture, light rays near the aperture must converge to pass through it. Since the first cemented lens is positioned closer to the second lens group 40, light rays exiting the second lens group 40 sequentially pass through the first cemented lens, the aperture, and the second cemented lens. In this embodiment, the refractive indices of the lenses in the first cemented lens are limited so that light rays exiting the second lens group 40 converge through the first cemented lens, then smoothly pass through the aperture and are then transmitted through the second cemented lens.

[0081] In one embodiment, referring to Figure 1 and Figure 2 , along the direction of incident transmission of the image light beam, the second cemented lens includes an eighth lens 8 and a seventh lens 7, the optical focal length of the eighth lens 8 is negative, the optical focal length of the seventh lens 7 is positive, and the refractive index of the seventh lens 7 is lower than the refractive index of the eighth lens 8.

[0082] In this embodiment, the refractive index of a lens with positive optical power is lower than that of a lens with negative optical power. The refractive index indicates the degree to which a lens refracts light; a higher refractive index indicates a greater degree of refraction. The Abbe number indicates the degree to which a lens medium disperses light; a lower Abbe number indicates greater dispersion, and thus a higher refractive index.

[0083] In this embodiment, the refractive index of the lens in the second cemented lens is limited so that the second cemented lens can eliminate chromatic aberration.

[0084] In an optional embodiment, the refractive index of the seventh lens 7 is in a range of 1.48 to 1.55, and the refractive index of the eighth lens 8 is in a range of 1.82 to 1.92.

[0085] In one embodiment, in the first lens group 30 , there is a third air gap between adjacent lenses, and the third air gap is less than 1 mm and greater than or equal to 0.1 mm.

[0086] In this embodiment, the air intervals between adjacent lenses in the first lens group 30 are limited, so that when the overall lens aperture in the first lens group 30 is small, the size of the first lens group 30 along the optical axis is also relatively small.

[0087] In this embodiment, the air gaps between adjacent lenses in the first lens group 30 are less than 1 mm in order to ensure that the total optical length of the projection lens is not too long and to reduce the volume of the projection lens. The air gaps between adjacent lenses in the first lens group 30 are greater than or equal to 0.1 mm in order to prevent the lenses from colliding with each other due to assembly tolerances.

[0088] Therefore, in this embodiment, the size of the projection lens is reduced primarily through the structure of the first lens group 30. Furthermore, the air gap between the first lens group 30 and the second lens group 40 is limited, as is the air gap between the aspheric reflector 13 and the second lens group 40. While reducing the size of the first lens group 30, the air gap between the first lens group 30 and the second lens group 40, as well as the air gap between the second lens group 40 and the aspheric reflector 13, can be maximized, thereby enabling the projection lens to project a larger image within a short distance.

[0089] In one embodiment, referring to Figure 1 and Figure 2 Along the direction of incident transmission of the image light beam, the first lens group 30 includes a twelfth lens 12, an eleventh lens 11, a tenth lens 10, a ninth lens 9, an eighth lens 8, a seventh lens 7, a sixth lens 6 and a fifth lens 5; the order of the optical power of the lenses in the first lens group 30 is: positive, positive, negative, positive, negative, positive, positive, negative.

[0090] In this embodiment, the first lens group 30 includes eight lenses, wherein the second lens group 40 includes four lenses, and in conjunction with the aspheric reflector 13, the projection lens is reduced in size while ensuring imaging quality through the use of 13 lenses.

[0091] Specifically, the number of lenses in the first lens group 30 is greater than the number of lenses in the second lens group 40 , mainly to reduce the lens aperture of the first lens group 30 and the size of the first lens group 30 on the optical axis as much as possible to minimize the volume of the projection lens.

[0092] In this embodiment, the twelfth lens 12 has a positive optical power and is a biconvex lens; the eleventh lens 11 has a positive optical power and is a biconvex lens; the tenth lens 10 has a negative optical power and has a concave first surface and a flat second surface; the ninth lens 9 has a positive optical power and has a convex first surface and a flat second surface; the eighth lens 8 has a negative optical power and has a flat first surface and a concave second surface; the seventh lens 7 has a positive optical power and has a convex first surface and a concave second surface; the sixth lens 6 has a positive optical power and has a convex first surface and a convex second surface; and the fifth lens 5 has a negative optical power and has a concave first surface and a flat second surface. The first surface of each lens is the surface closest to the image source 17, and the second surface is the surface closest to the aspheric reflector 13. This embodiment limits the number of lenses in the first lens group 30 and the optical power of each lens to ensure imaging quality.

[0093] In this embodiment, the first lens group 30 has a positive optical power, and the second lens group 40 has a negative optical power, thereby enabling optical imaging. This application utilizes 13 lenses to achieve an ultra-short-throw, wide-field-of-view projection lens configuration, while also improving the imaging performance of the projection lens while reducing its tolerance sensitivity.

[0094] In one embodiment, Figure 1 and Figure 2 The eleventh lens 11 and the tenth lens 10 are cemented together to form a third cemented lens.

[0095] In this embodiment, the eleventh lens 11 and the tenth lens 10 are cemented together to form a third cemented lens, and chromatic aberration can be eliminated by the third cemented lens.

[0096] Therefore, in this embodiment, the first lens group 30 includes three groups of cemented lenses, wherein the third cemented lens is located between two lenses with positive optical power, the first cemented lens and the second cemented lens are respectively located on both sides of the aperture, and an aspheric lens with positive optical power is arranged between the second cemented lens and the third cemented lens. By designing the lenses in the first lens group 30, the size of the first lens group 30 on the optical axis can be further reduced, and the imaging picture quality can be further improved.

[0097] In one embodiment, referring to Figure 1 and Figure 2 The ninth lens 9 is an aspherical lens, and the twelfth lens 12, the eleventh lens 11, the tenth lens 10, the eighth lens 8, the seventh lens 7, the sixth lens 6 and the fifth lens 5 are all spherical lenses.

[0098] In this embodiment, only one aspherical lens is included in the first lens group 30, and the remaining seven lenses are all spherical lenses. Therefore, fewer aspherical lenses are used in the first lens group 30 to process the optical path, which reduces the difficulty of assembling the first lens group 30 and also reduces the cost of the projection lens.

[0099] In one embodiment, after the image beam passes through the first lens group 30 and the second lens group 40, a first image is formed between the second lens group 40 and the aspheric reflector 13. The aspheric reflector 13 reflects the first image onto the projection screen to form a projection image. The width of the projection image is c1.

[0100] In the width direction of the projection screen, the distance between the projection screen and the optical axis is c2, wherein the range of c2 / c1 is 38%-42%.

[0101] In this implementation, the offset is the distance between the projection image and the optical axis divided by the width of the projection image. Setting the offset within this range ensures that the projection image is not obstructed by other structural components, facilitating the design of the projection optical engine. In this embodiment, the ratio c1 / c2 is between 38% and 42%. The image beam is projected obliquely onto the projection screen, and the projection image is eccentric to the optical axis. In one example, the ratio c2 / c1 is 40%.

[0102] In this embodiment, reference Figure 9 As shown, the projection screen a can be a wall or a desktop. In this embodiment, the projection ratio of the projection lens is between 0.20 and 0.23, for example, the projection ratio is 0.21. The projection ratio refers to the ratio of the distance b between the projection lens and the projection screen to the width c1 of the projected image. The smaller the projection ratio, the closer the projection lens or projection device is to the projection screen, or the larger the projected image size.

[0103] In a second aspect, an electronic device is provided. The electronic device includes the projection lens described above. For example, the electronic device may be a projection light machine or an illumination light machine. For example, it may be a projection lens for a desktop projection product or a projection lens for a wall projection product. In a specific embodiment, referring to Figure 9 As shown, the projection lens is placed vertically in the optical machine, and the projected image is projected onto the desktop. When the human eye views the image on the desktop, the effect is similar to viewing a tablet on the desktop.

[0104] Example 1

[0105] In a specific embodiment, referring to Figure 1 As shown, along the direction of incident transmission of the image beam, the projection lens includes an image source 17, a flat glass 16, a prism 15, a galvanometer mirror 14, a twelfth lens 12, an eleventh lens 11, a tenth lens 10, a ninth lens 9, an eighth lens 8, a seventh lens 7, a sixth lens 6, a fifth lens 5, a fourth lens 4, a third lens 3, a second lens 2, a first lens 1, and an aspheric reflector 13. In this embodiment, the aspheric reflector 13 is a curved aspheric reflector 13.

[0106] In this embodiment, reference Figure 1 As shown, along the direction of incident transmission of the image light beam, the order of the optical focal length of the above lenses is: positive, positive, negative, positive, negative, positive, positive, negative, positive, positive, negative, negative, negative.

[0107] The aperture is located between the sixth lens 6 and the seventh lens 7. The eleventh lens 11 and the tenth lens 10 are cemented to form a third cemented lens; the eighth lens 8 and the seventh lens 7 are cemented to form a second cemented lens; and the sixth lens 6 and the fifth lens 5 are cemented to form a first cemented lens.

[0108] In this embodiment, reference Figure 1 As shown, in the first lens group 30, the twelfth lens 12 is a biconvex lens; the eleventh lens 11 is a biconvex lens; the first surface of the tenth lens 10 is a concave surface, and the second surface is a plane; the first surface of the ninth lens 9 is a convex surface, and the second surface is a plane; the first surface of the eighth lens 8 is a plane, and the second surface is a concave surface; the first surface of the seventh lens 7 is a convex surface, and the second surface is a concave surface; the first surface of the sixth lens 6 is a convex surface, and the second surface is a convex surface; the first surface of the fifth lens 5 is a concave surface, and the second surface is a plane, wherein the first surface of each lens is the surface close to the image source 17, and the second surface is the surface close to the aspheric reflector 13.

[0109] In this embodiment, in the first lens group 30 , the ninth lens 9 is a glass aspherical lens, and the remaining lenses are all spherical lenses.

[0110] In second lens group 40, fourth lens 4 is a biconvex lens, third lens 3 has a convex first surface and a concave second surface, second lens 2 has a concave first surface and a convex second surface, and first lens 1 has a concave first surface and a concave second surface. The first surface of each lens is the surface closest to image source 17, and the second surface is the surface closest to aspheric reflector 13.

[0111] In this embodiment, the first lens 1 and the fourth lens 4 are both plastic aspherical lenses, and the second lens 2 and the third lens 3 are both spherical lenses.

[0112] In this embodiment, the effective focal length of the projection lens is -1.5mm to -1.2mm, and the projection lens is an ultra-short-throw projection lens. The effective focal length range of the aspheric reflector 13 is 17mm to 20mm; the effective focal length range of the first lens 1 is -23mm to -20mm; the effective focal length range of the second lens 2 is -95mm to -92mm; the effective focal length range of the third lens 3 is 100mm to 110mm; the effective focal length range of the fourth lens 4 is 55mm to 58mm; the effective focal length range of the fifth lens 5 is 870mm to 880mm; and the effective focal length range of the sixth lens 6 is The effective focal length range of the seventh lens element 7 is 36mm to 39mm; the effective focal length range of the eighth lens element 8 is -43mm to -40mm; the effective focal length range of the ninth lens element 9 is 16mm to 19mm; the effective focal length range of the tenth lens element 10 is -47mm to -44mm; the effective focal length range of the eleventh lens element 11 is -240mm to -250mm; and the effective focal length range of the twelfth lens element 12 is 21mm to 24mm.

[0113] In this embodiment, the surface shape of the lens in the projection lens is limited, and the optical power of the lens is reasonably distributed, which is conducive to reducing tolerance sensitivity and reducing the difficulty of assembling the projection lens.

[0114] The specific parameters of each lens are shown in Table 1 below:

[0115]

[0116] Table 1

[0117] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4 and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 2:

[0118]

[0119] Table 2

[0120] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0121] After measurement, the field of view parameters of the above optical imaging module are as follows: Figures 6 to 8 shown.

[0122] like Figure 6 The figure shows the modulation transfer function (MTF) of this embodiment. The horizontal axis represents the spatial frequency (in cycles per mm), and the vertical axis represents the OTF modulus. The figure shows that within the spatial frequency range of 0mm-93mm, the OTF modulus of the image consistently remains above 0.5. Generally speaking, the closer the OTF modulus is to 1, the higher the image quality. However, due to various factors, an OTF modulus of 1 does not exist. Generally, when the OTF modulus is maintained above 0.5, it indicates high image quality and excellent picture clarity. Therefore, it can be seen that the ultra-short-throw projection lens of this embodiment has higher imaging quality.

[0123] like Figure 7 The relative illumination diagram of this embodiment is shown. It can be seen from the diagram that the relative illumination satisfies the application of the projection lens. The relative illumination is ≥0.7.

[0124] like Figure 8 The figure shows the distortion of this embodiment. It can be seen from the figure that the distortion range is less than 1.2%, and the distortion is small.

[0125] Example 2

[0126] The difference between Example 2 and Example 1 is that the curvature radius, thickness of each lens and the parameters of the aspheric lens are different. In this embodiment, the specific parameters of each lens are shown in Table 3 below:

[0127]

[0128]

[0129] Table 3

[0130] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4 and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 4:

[0131]

[0132] Table 4

[0133] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0134] Example 3

[0135] The difference between Example 3 and Example 1 is that the curvature radius, thickness of each lens and the parameters of the aspheric lens are different. In this embodiment, the specific parameters of each lens are shown in Table 5 below:

[0136]

[0137]

[0138] Table 5

[0139] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4 and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 6:

[0140]

[0141] Table 6

[0142] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0143] Example 4

[0144] The difference between Example 4 and Example 1 is that the curvature radius and thickness of each lens and the parameters of the aspheric lens are different. In this example, the specific parameters of each lens are shown in Table 7 below:

[0145]

[0146] Table 7

[0147] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4 and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 8:

[0148]

[0149]

[0150] Table 8

[0151] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0152] Example 5

[0153] The difference between Example 5 and Example 1 is that the curvature radius, thickness of each lens and the parameters of the aspheric lens are different. In this embodiment, the specific parameters of each lens are shown in Table 9 below:

[0154]

[0155] Table 9

[0156] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4 and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 10:

[0157]

[0158] Table 10

[0159] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0160] Example 6

[0161] The difference between Example 6 and Example 1 is that the curvature radius and thickness of each lens and the parameters of the aspheric lens are different. In this embodiment, the specific parameters of each lens are shown in Table 11 below:

[0162]

[0163]

[0164] Table 11

[0165] In this embodiment, the aspheric reflector 13, the first lens 1, the fourth lens 4, and the ninth lens 9 are all aspheric lenses, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspheric lenses are shown in Table 12:

[0166]

[0167] Table 12

[0168] In this embodiment, the projection lens is suitable for a 0.33-inch DMD design. The projection lens can achieve the following effects: a throw ratio of 0.21, a system effective focal length of -1.5mm to -1.2mm, a half field of view of 75° to 85°, a field of view of 150° to 170°, an image circle diameter of 11mm to 12mm, and a system F-number of 1.65 to 1.75.

[0169] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0170] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection lens, characterized in that: The projection lens comprises, in sequence along the direction of incident transmission of the image light beam: a first lens group (30), a second lens group (40) and an aspheric reflector (13); the first lens group (30), the second lens group (40) and the aspheric reflector (13) are located on the same optical axis; the optical focal length of the first lens group (30) is positive, and the optical focal length of the second lens group (40) is negative; There is a first air gap between the first lens group (30) and the second lens group (40), the first air gap ranges from 30 mm to 45 mm, and the first air gap accounts for 12% to 17% of the total optical length of the projection lens; Along the direction of incident transmission of the image light beam, the first lens group (30) includes a twelfth lens (12), an eleventh lens (11), a tenth lens (10), a ninth lens (9), an eighth lens (8), a seventh lens (7), a sixth lens (6) and a fifth lens (5), and the order of the optical focal lengths of the lenses in the first lens group (30) is: positive, positive, negative, positive, negative, positive, positive, positive, negative; the second lens group (40) includes a fourth lens (4), a third lens (3), a second lens (2) and a first lens (1), and the order of the optical focal lengths of the lenses in the second lens group (40) is: positive, positive, negative, negative, and the number of lenses with optical focal lengths in the projection lens is 12.

2. The projection lens according to claim 1, wherein: A second air gap is provided between the second lens group (40) and the aspheric reflector (13), the second air gap ranges from 95 mm to 105 mm, and the second air gap accounts for 41% to 45% of the total optical length of the projection lens.

3. The projection lens according to claim 1, wherein: Along the direction of incident transmission of the image light beam, the second lens group (40) includes a positive lens group (41) and a negative lens group (42), the positive lens group (41) includes at least one lens with positive optical power, and the negative lens group (42) includes at least one lens with negative optical power.

4. The projection lens according to claim 3, wherein: The optical focal length of the positive lens group (41) is in the range of 0.018 to 0.038, and the optical focal length of the negative lens group (42) is in the range of -0.068 to -0.

048.

5. The projection lens according to claim 1, wherein: The fourth lens (4) and the first lens (1) are both aspherical lenses, and the third lens (3) and the second lens (2) are both spherical lenses.

6. The projection lens according to claim 1, wherein: The first lens group (30) comprises an aperture, a first cemented lens and a second cemented lens, the first cemented lens and the second cemented lens are located on both sides of the aperture, and the first cemented lens is closer to the second lens group (40) than the second cemented lens.

7. The projection lens according to claim 6, wherein: Along the direction of incident transmission of the image light beam, the first cemented lens includes a sixth lens (6) and a fifth lens (5), the optical focal length of the sixth lens (6) is positive, the optical focal length of the fifth lens (5) is negative, and the refractive index of the sixth lens (6) is higher than the refractive index of the fifth lens (5).

8. The projection lens according to claim 6, wherein: Along the direction of incident transmission of the image light beam, the second cemented lens includes an eighth lens (8) and a seventh lens (7), the optical focal length of the eighth lens (8) is negative, the optical focal length of the seventh lens (7) is positive, and the refractive index of the seventh lens (7) is lower than the refractive index of the eighth lens (8).

9. The projection lens according to claim 8, wherein: The refractive index of the seventh lens (7) is in the range of 1.48 to 1.55, and the refractive index of the eighth lens (8) is in the range of 1.82 to 1.

92.

10. The projection lens according to claim 1, wherein: In the first lens group (30), there is a third air gap between adjacent lenses, and the third air gap range is less than 1 mm and greater than or equal to 0.1 mm.

11. The projection lens according to claim 1, wherein: The eleventh lens (11) and the tenth lens (10) are cemented together to form a third cemented lens.

12. The projection lens according to claim 1, wherein: The ninth lens (9) is an aspherical lens, and the twelfth lens (12), the eleventh lens (11), the tenth lens (10), the eighth lens (8), the seventh lens (7), the sixth lens (6) and the fifth lens (5) are all spherical lenses.

13. The projection lens according to claim 1, wherein: After the image light beam passes through the first lens group (30) and the second lens group (40), a first imaging is performed between the second lens group (40) and the aspheric reflector (13), and the aspheric reflector (13) reflects the first imaging to the projection screen to form a projection image, and the width of the projection image is c1; In the width direction of the projection screen, the distance between the projection screen and the optical axis is c2, wherein the range of c2 / c1 is 38%-42%.

14. An electronic device, characterized in that: The electronic device comprises the projection lens according to any one of claims 1 to 13.

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