CN116841008A - projection lens - Google Patents

Abstract

The invention relates to the technical field of projection, and provides a projection lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are sequentially arranged from an image source side to an imaging side at intervals along an optical axis, the first lens has positive focal power, the second lens has positive focal power, the third lens has positive focal power, the fourth lens has negative focal power, the fifth lens has positive focal power, and the sixth lens has negative focal power. The object-oriented imaging system comprises an object, an imaging source, a lens array and a lens array, wherein the object positioned on the image source side emits light rays, six lenses are sequentially arranged, and air spaces between adjacent lenses are used for correcting aberration; the positive focal power can reduce the aperture of the light beam; the negative optical power is helpful for reducing chromatic aberration and improving resolution; the projection lens adopts six lenses to mutually match, is suitable for the projection of the article with large line diameter, has strong resolving power, is favorable for forming a projection image with clear pattern image, sharp facula edge and high facula uniformity, and has better imaging capability on the article with large line diameter.

Description

Projection lens

Technical Field

The present disclosure relates to projection technology, and particularly to a projection lens.

Background

Projection lenses are often used in photographic lighting, stage lighting applications. Specifically, the shaping condensing device converges light emitted by the stage lamp or the photographic lighting lamp into small enough light spots, the pattern sheets are placed or emptied at the light spots, the projection lens is placed at one side of the pattern sheets far away from the shaping condensing device, so that the object focal plane of the projection lens is overlapped with the light spots and the pattern sheets, the projection lens projects the light spots or the pattern sheets onto a surface to be illuminated, a projection image with clear pattern images and sharp light spot edges is formed, and a special lighting effect is achieved.

At present, a stage lamp or a photographic lighting lamp uses a high-power expansion light source, the light emitting area of the expansion light source is large, and light spots converged by the shaping light-gathering device are large, namely the object height of a projection lens is large, so that the aperture of an optical glass lens used by the projection lens is increased. In order to improve the utilization rate of the system to the light energy, the projection lens needs to have better imaging capability to the object with larger line diameter. However, it is difficult to project an object having a large line diameter by using the conventional projection lens.

Disclosure of Invention

The application aims to provide a projection lens and aims to solve the technical problem that an existing projection lens is difficult to project an object with a large line diameter.

The application provides a projection lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged at intervals along an optical axis from an image source side to an imaging side, wherein the first lens has positive focal power, the second lens has positive focal power, the third lens has positive focal power, the fourth lens has negative focal power, the fifth lens has positive focal power and the sixth lens has negative focal power.

In one embodiment, the first lens has an optical power of 0.0048-0.0056.

In one embodiment, the second lens has an optical power of 0.0045-0.0055.

In one embodiment, the third lens has an optical power of 0.0068-0.0076.

In one embodiment, the focal power of the fourth lens is-0.0019 to-0.015.

In one embodiment, the optical power of the fifth lens is 0.0101-0.0125.

In one embodiment, the sixth lens has an optical power of-0.0058 to-0.0048.

In one embodiment, the first lens has a first face near the image source side and a second face far from the image source side, the first face being a plane, the second face being a convex face.

In one embodiment, the second lens has a third face near the image source side and a fourth face far from the image source side, both of which are convex.

In one embodiment, the third lens has a fifth surface near the image source side and a sixth surface far from the image source side, the fifth surface being a convex surface, the sixth surface being a concave surface.

In one embodiment, the fourth lens has a seventh face near the image source side and an eighth face far from the image source side, both the seventh face and the eighth face being concave.

In one embodiment, the fifth lens has a ninth face near the image source side and a tenth face far from the image source side, both of which are convex.

In one embodiment, the sixth lens has a tenth surface near the image source side and a tenth surface far from the image source side, the tenth surface being concave, and the tenth surface being convex.

In one embodiment, the radius of the fourth face is greater than the radius of the third face.

In one embodiment, the radius of the sixth face is greater than the radius of the fifth face.

In one embodiment, the radius of the eighth face is smaller than the radius of the seventh face.

In one embodiment, the radius of the tenth face is smaller than the radius of the ninth face.

In one embodiment, the radius of the tenth face is greater than the radius of the tenth face.

In one embodiment, a ratio of the radius of the fourth surface to the radius of the third surface is 3.47-3.51.

In one embodiment, a ratio of the radius of the sixth surface to the radius of the fifth surface is 3.63-3.71.

In one embodiment, the ratio of the radius of the eighth face to the radius of the seventh face is 0.35-0.36.

In one embodiment, the ratio of the radius of the tenth surface to the radius of the ninth surface is 0.435 to 0.455.

In one embodiment, the ratio of the radius of the tenth surface to the radius of the tenth surface is 2.447-2.457.

In one embodiment, a distance between a side surface of the first lens, which is close to the second lens, and a side surface of the second lens, which is close to the first lens, on an optical axis is 0.8 mm-1.2 mm.

In one embodiment, a distance between a side surface of the second lens, which is close to the third lens, and a side surface of the third lens, which is close to the second lens, on an optical axis is 0.8 mm-1.2 mm.

In one embodiment, a distance between a side surface of the third lens, which is close to the fourth lens, and a side surface of the fourth lens, which is close to the third lens, on an optical axis is 11.2 mm-11.8 mm.

In one embodiment, a distance between a side surface of the fourth lens, which is close to the fifth lens, and a side surface of the fifth lens, which is close to the fourth lens, on an optical axis is 38.0mm to 39.0mm.

In one embodiment, a distance between a side surface of the fifth lens, which is close to the sixth lens, and a side surface of the sixth lens, which is close to the fifth lens, on an optical axis is 50.5mm to 51.5mm.

In one embodiment, the refractive index of the first lens is 1.483-1.490.

In one embodiment, the refractive index of the second lens is 1.615-1.625.

In one embodiment, the refractive index of the third lens is 1.615-1.625.

In one embodiment, the refractive index of the fourth lens is 1.750-1.760.

In one embodiment, the refractive index of the fifth lens is 1.632-1.642.

In one embodiment, the refractive index of the sixth lens is 1.483-1.490.

In one embodiment, the scattering coefficient of the first lens is 70.40-70.45.

In one embodiment, the scattering coefficient of the second lens is 60.0-60.5.

In one embodiment, the scattering coefficient of the third lens is 60.0-60.5.

In one embodiment, the scattering coefficient of the fourth lens is 27.53-27.57.

In one embodiment, the scattering coefficient of the fifth lens is 55.44-55.49.

In one embodiment, the scattering coefficient of the sixth lens is 70.40-70.45.

In one embodiment, the thickness of the edges of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens ranges from 3mm to 5mm, and the thickness on the optical axis is greater than 2.0mm.

In one embodiment, the effective focal length of the projection lens is 86.45 mm-87.50 mm.

In one embodiment, the angle of view of the projection lens is 50 ° to 60 °.

The projection lens provided by the invention has the beneficial effects that: light rays emitted by an object positioned on the image source side sequentially pass through the six lenses such as the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens, and the air interval between the adjacent lenses is used for correcting aberration; the first lens, the second lens and the third lens all have positive focal power, can collect light rays, and continuously reduce the caliber of a light beam emitted by an object with a large line diameter; the fourth lens has negative focal power, has a divergent effect on the light beam, and is beneficial to reducing chromatic aberration and improving resolution capability; the fifth lens has positive focal power, can reduce the caliber of the light beam again, and balances the positive spherical aberration generated by the negative lens; the sixth lens has negative focal power, further reduces chromatic aberration and improves resolution capability, and projects the light beam to an imaging side; the projection lens adopts six lenses to mutually match, is suitable for the projection of the article with large line diameter, has strong resolving power, solves the technical problem that the existing projection lens is difficult to project the article with large line diameter, is favorable for forming a projection image with clear pattern image, sharp facula edge and high facula uniformity, and has better imaging capability for the article with large line diameter.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an optical path of a projection lens according to an embodiment;

FIG. 3 is a graph showing curvature of field and distortion of a projection lens at a second working distance of 2500 mm;

FIG. 4 is a diffuse speckle pattern of a projection lens with a second working distance of 2500 mm;

FIG. 5 is a schematic view showing spot uniformity of a projection lens at a second working distance of 2500 mm;

FIG. 6 is a graph of MTF of a projection lens at a second working distance of 2500 mm;

FIG. 7 is a graph showing curvature of field and distortion of a projection lens at a second working distance of 5000 mm;

FIG. 8 is a diffuse speckle pattern for a projection lens with a second working distance of 5000 mm;

FIG. 9 is a schematic view of spot uniformity of a projection lens at a second working distance of 5000 mm;

fig. 10 is an MTF plot of a projection lens at a second working distance of 5000 mm.

Wherein, each reference sign in the figure:

1. a projection lens; 2. an article; 3. a screen;

10. a first lens; 11. a first face; 12. a second face;

20. a second lens; 21. a third face; 22. a fourth face;

30. a third lens; 31. a fifth surface; 32. a sixth face;

40. a fourth lens; 41. a seventh face; 42. eighth face;

50. a fifth lens; 51. a ninth face; 52. a tenth surface;

60. a sixth lens; 61. a tenth surface; 62. and a second face.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrase "in one embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In the description of the present invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Referring to fig. 1, a projection lens 1 of the present application includes a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, which are disposed in order from an image source side (object 2) to an image forming side (screen 3) along an optical axis O. For example, the shaping condensing device condenses the light emitted by the stage light fixture or the photographic lighting fixture into a small enough light spot on the image source side, and the object 2 is placed or emptied on the image source side, and the object 2 may be a pattern piece. The imaging side is placed with the screen 3 or the imaging side is a wall or floor. The light rays emitted by the object 2 positioned on the image source side sequentially pass through the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, the sixth lens 60 and the like, and then are projected on the imaging side, the air interval between the adjacent lenses is used for correcting aberration, the problem that the bonding surface is easy to generate aberration due to contact bonding between the lenses is avoided, and the lens interval is favorable for improving the focal length.

Wherein, in connection with fig. 2, the first lens 10 has positive optical power, the second lens 20 has positive optical power, the third lens 30 has positive optical power, the fourth lens 40 has negative optical power, the fifth lens 50 has positive optical power, and the sixth lens 60 has negative optical power. When the line diameter of the light spot is large, or the line diameter of the object 2 (such as a pattern sheet) is large, that is, the object height is too large, the light spot or the object 2 is difficult to be imaged completely, at this time, since the first lens 10, the second lens 20 and the third lens 30 all have positive focal power, light rays can be converged, and the light beam emitted from the image source side sequentially passes through the first lens 10, the second lens 20 and the third lens 30 at first, the caliber of the light beam is continuously reduced, and the imaging capability of the projection lens 1 is improved. If only one lens with positive power is used, the same condensing effect cannot be achieved, and the imaging distortion of a single lens with large positive power is large. The fourth lens 40 has negative focal power, and has a divergent effect on the light beam, which helps to reduce aberration generated by the first three lenses and improve resolution. The fifth lens 50 has positive power, and can reduce the aperture of the light beam again while balancing the positive spherical aberration generated by the fourth lens 40 of the negative lens. The sixth lens 60 has negative power, further reduces aberration and improves resolution, projecting the light beam to the imaging side.

In this embodiment, the projection lens 1 adopts six lenses to mutually cooperate, positive and negative focal power is reasonably distributed, focal power is basically balanced, and the projection lens is suitable for projection of an object 2 with a large line diameter, has strong resolving power, is favorable for forming a projection image with clear pattern image, sharp light spot edge and high light spot uniformity, has better imaging capability for the object 2 with a large line diameter, improves the light projecting efficiency of a high-power LED lamp, has a certain resolving power, and brings great convenience for shooting scenes.

In one embodiment, the effective focal length of the projection lens 1 is 86.45mm to 87.50mm. Optionally, the effective focal length of the projection lens 1 is 86.45mm, 86.45mm, 86.50mm, 86.52mm or 87.50mm.

In one embodiment, the combination of the six lenses enables the angle of view of the projection lens 1 to reach 50 ° to 60 °, that is, the light emitted from the image source side is within the angle of view, and can all pass through the projection lens 1, so that the imaging capability of the projection lens has a large angle of view.

Optionally, the field angle of the projection lens 1 is 50 °, 53 °, 55 °, 56 °, 58 °, or 60 °.

Specifically, the radius of the first lens 10 is 60mm, and the air space between the first lens 10 and the object 2 on the optical axis O is a first working distance Lw, which is smaller than 70mm. Optionally, the first working distance Lw is 50mm, 60mm or 70mm. At this time, the maximum diameter of the projected object 2 may reach 85mm, that is, the object height radius is 42.5mm, and the projection lens 1 can satisfy an angle of view of 55 °. At any point on the object 2, under the condition of object space cone angle, the main optical axis O is parallel to the main optical axis O of the system, namely, the object space is telecentric.

In the present application, the radius of the first lens 10 is 58mm to 62mm, i.e. half the height of the first lens 10 in fig. 1. Since the light emitted from the image source side is first diverged and directed to the first lens 10, and since the radius of the first lens 10 is limited, and the first lens 10 has positive optical power, the light passing through the first lens 10 converges, and the light not passing through the first lens 10 continues to diverge and is separated from the projection lens 1, so that separation is realized, i.e., the first lens 10 is equivalent to an aperture stop. The aperture diaphragm can improve the imaging quality of the outer point of the optical axis O, control the depth of field, improve the imaging quality and improve the definition of the image.

Alternatively, the radius of the first lens 10 is 58mm, 60mm or 62mm.

Specifically, with reference to fig. 1, since the optical powers of the first lens 10, the second lens 20 and the third lens 30 are positive, the light is continuously converged, and the aperture of the light beam is gradually reduced, so that the diameters of the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are gradually reduced, and the next lens can still receive the light beam emitted by the last lens, and the size reduction and the weight reduction of the projection lens 1 are facilitated.

Specifically, the diameters of the fourth lens 40, the fifth lens 50, and the sixth lens 60 gradually increase.

In the optical arts, optical power is commonly referred to by the letter phi, which is equal to the difference between the convergence of image Fang Guangshu and the convergence of the object beam, and which characterizes the ability of the optical system to deflect light. The larger the value of the optical power phi, the more the parallel beam is folded; at phi >0, the refractive index is convergent; at phi <0, the refraction is divergent. Phi=0, no refraction phenomenon occurs corresponding to planar refraction.

Aberration is a phenomenon of ideal imaging of off-paraxial rays due to off-paraxial rays in an actual optical system, and mainly includes spherical aberration, coma, chromatic aberration, astigmatism, curvature of field, distortion, and the like.

The scattering coefficient, also known as the "Abbe number" or "Abbe number", is used to measure the degree of light dispersion of a transparent medium and is denoted by vd. In general, the larger the refractive index n of the medium, the more severe the dispersion, and the smaller the scattering coefficient vd; conversely, the smaller the refractive index n of the medium, the more slight the dispersion and the larger the scattering coefficient vd. The calculation formula of the scattering coefficient vd is vd= (nd-1)/(nF-nC), and nd, nF, and nC are refractive indexes of D light, F light, and C light, respectively. In the present application, light D employs light having a wavelength of 557.6nm, light F employs light having a wavelength of 435.1nm, and light C employs light having a wavelength of 656.3 nm.

In the present application, specific parameters of the projection lens 1 are shown in table 1.

TABLE 1 projection lens parameter table

In some embodiments, referring to table 1, fig. 1 and fig. 2, the optical power Φ of the first lens 10 is 0.0048-0.0056, so the first lens 10 has a condensing effect, and the optical power Φ has a small value, light ray bending and aberration are small.

Optionally, the optical power φ of the first lens 10 is 0.0048, 0.0050, 0.0052, 0.0053, 0.0054 or 0.0056.

In one embodiment, the first lens 10 has a first face 11 near the image source side and a second face 12 far from the image source side. The first surface 11 is a plane, and light rays emitted from the image source side directly enter the first surface 11 through an air gap, and the plane has no refraction and no aberration. The second surface 12 is a convex surface, so that light condensation is realized, the aperture of a light beam with a high object height can be reduced, and imaging is facilitated.

Specifically, the radius r of the spherical surface corresponding to the second surface 12 is 92.7 mm-92.9 mm, the radius value is larger, the surface of the second surface 12 is flat, preliminary light condensation is performed in a small amplitude, and the influence on aberration is small. The center of the second surface 12 is located on the side of the first lens 10 close to the object 2.

Alternatively, the radius r of the second face 12 is 92.7mm, 92.8mm or 92.9mm.

Specifically, the edge thickness of the first lens 10 ranges from 3mm to 5mm, so that the influence of light reflection on the definition of an image caused by excessive edge thickness is avoided, and the generation of aberration caused by too short light stroke caused by too small edge thickness is also avoided; the thickness d on the optical axis O is greater than 2.0mm, avoiding blurring and deformation of the image caused by easy deformation of the first lens 10.

Alternatively, the edge thickness of the first lens 10 is 5mm, and the thickness d on the optical axis O is 27mm.

In one embodiment, the refractive index n of the first lens 10 is 1.483-1.490, which is a low refractive index lens, and is beneficial to reducing chromatic aberration. Alternatively, the refractive index n of the first lens 10 is 1.483, 1.485, 1.487, 1.488, or 1.490.

In one embodiment, the scattering coefficient vd of the first lens 10 is 70.40-70.45, and the scattering coefficient is higher, so that the aberration generated is smaller, and higher imaging quality can be provided. Optionally, the scattering coefficient vd of the first lens 10 is 70.40, 70.42, 70.43, 70.44 or 70.45.

In one embodiment, a distance d1 between a side surface of the first lens 10 adjacent to the second lens 20 and a side surface of the second lens 20 adjacent to the first lens 10 on the optical axis O is 0.8mm to 1.2mm. Having an air gap between the first lens 10 and the second lens 20 is advantageous in reducing aberrations. The space between the two is smaller, the light transition is satisfied, the structure is compact, and the volume is small.

Alternatively, the distance d1 of the first lens 10 and the second lens 20 on the optical axis O is 0.8mm, 0.9mm, 1.0mm, or 1.2mm.

For example, referring to fig. 2, under the parameters defined in table 1, the half-aperture y of the light beam emitted from the image source side by the object 2 is 42.5mm, the half-aperture of the light beam is 59.5mm on the first surface 11, and when the light beam is scattered onto the second surface 12 without meandering, the half-aperture of the light beam is increased to 62.0mm. When the light beam is refracted at the second surface 12 and reaches the second lens 20 after passing through the air space d between the first lens 10 and the second lens 20, the half-aperture of the light beam is 56.5mm. The air gap d facilitates the gradual extension of the aperture of the light beam.

In some embodiments, referring to table 1, fig. 1 and fig. 2, the optical power Φ of the second lens 20 is 0.0045-0.0055, so the second lens 20 has a condensing effect, and the optical power Φ is smaller, the light ray is less tortuous, and the image is good.

Optionally, the optical power φ of the second lens 20 is 0.0045, 0.0048, 0.0049, 0.0050, 0.0053 or 0.0055.

In one embodiment, the second lens 20 has a third surface 21 near the image source side and a fourth surface 22 far from the image source side, and both the third surface 21 and the fourth surface 22 are convex, so as to further reduce the beam diameter.

Specifically, the radius of the sphere corresponding to the fourth surface 22 is larger than the radius of the sphere corresponding to the third surface 21, and the light is stably transmitted in the second lens element 20 after being refracted at the third surface 21, so as to facilitate the correction of the light, and the light enters the third lens element 30 after being corrected in air after being refracted at the fourth surface 22. The light rays are better corrected in the second lens 20 than in air.

It will be appreciated that in other embodiments, the radius of the sphere corresponding to the fourth face 22 is smaller than the radius of the sphere corresponding to the third face 21.

Optionally, the thickness of the edge of the second lens 20 ranges from 3mm to 5mm, and the thickness on the optical axis O is greater than 2.0mm. For example, the edge thickness of the second lens 20 is 4mm, and the thickness d on the optical axis O is 16mm.

Optionally, the distance d2 between the side surface of the second lens 20, which is close to the third lens 30, and the side surface of the third lens 30, which is close to the second lens 20, on the optical axis O is 0.8mm to 1.2mm, which is favorable for the compact structure and small volume of the projection lens 1. For example, the distance d2 of the second lens 20 and the third lens 30 on the optical axis O is 0.8mm, 0.9mm, 1.0mm, 1.1mm, or 1.2mm.

Optionally, the travel of the light ray in the second lens 20 is larger than the air travel of the light ray between the second lens 20 and the third lens 30, so as to further improve the correction effect of the light ray in the second lens 20.

Specifically, the ratio of the radius of the sphere corresponding to the fourth surface 22 to the radius of the sphere corresponding to the third surface 21 is 3.47-3.51, so that the refraction degree of the light can be controlled, the light can be converged, and large aberration can be avoided. The ratio of the radius of the fourth face 22 to the radius of the third face 21 may be specifically selected to be 3.47, 3.48, 3.49 or 3.51.

Optionally, the radius r of the corresponding sphere of the third face 21 is 157mm to 160mm, for example 157mm, 158mm, 159mm or 160mm. The radius r of the fourth face 22 is 553mm to 55mm, for example 553mm, 554mm or 555mm. The radius values of the third surface 21 and the fourth surface 22 are larger, the center of sphere of the third surface 21 is located at one side of the second lens 20 away from the object 2, and the center of sphere of the fourth surface 22 is located at one side of the second lens 20 close to the object 2.

For example, with reference to fig. 2, the half aperture of the beam is 56.5mm when the beam is on the third face 21, under the parameters defined in table 1. When the beam is on the fourth surface 22, the half aperture of the beam is 55.7mm. When the air space of the light beam passing through the second lens 20 and the third lens 30 reaches the third lens 30, the half aperture of the light beam is 45.0mm.

In one embodiment, the refractive index n of the second lens 20 is 1.615-1.625, and the refractive index n is lower, so as to avoid large aberration of the light beam. For example, the refractive index n of the second lens 20 is 1.615, 1.618, 1.620, 1.622, or 1.625.

In one embodiment, the scattering coefficient vd of the second lens 20 is 60.0-60.5, and the scattering coefficient vd is larger and the generated aberration is small. For example, the scattering coefficient vd of the second lens 20 is 60.0, 60.3, 60.4 or 60.5.

In some embodiments, the optical power Φ of the third lens 30 is 0.0068-0.0076, so the third lens 30 has a condensing effect, and the aperture of the light beam is further reduced.

Optionally, the third lens 30 has an optical power φ of 0.0068, 0.0070, 0.0072, 0.0074 or 0.0076.

In one embodiment, the refractive index n of the third lens 30 is 1.615-1.625, and the refractive index n is lower. For example, the refractive index n of the third lens 30 is 1.615, 1.618, 16.20, 1.622, or 1.625.

In one embodiment, the scattering coefficient vd of the third lens 30 is 60.0-60.5. For example, the scattering coefficient vd of the third lens 30 is 60.0, 60.2, 60.3, 60.4 or 60.5.

Specifically, the thickness of the edge of the third lens 30 ranges from 3mm to 5mm, and the thickness on the optical axis O is greater than 2.0mm. Alternatively, the edge thickness of the third lens 30 is 5mm, and the thickness d on the optical axis O is 18mm.

Specifically, a distance d3 between the side surface of the third lens 30 near the fourth lens 40 and the side surface of the fourth lens 40 near the third lens 30 on the optical axis O is 11.2mm to 11.8mm, for example, 11.2mm, 11.5mm, 11.6mm, or 11.8mm may be selected.

In one embodiment, the third lens 30 has a fifth surface 31 near the image source side and a sixth surface 32 far from the image source side, the fifth surface 31 being convex and the sixth surface 32 being concave. The centers of the fifth surface 31 and the sixth surface 32 corresponding to the spherical surfaces are located at a side of the third lens element 30 away from the image source side.

Optionally, the radius of the sixth face 32 is larger than the radius of the fifth face 31, i.e. the sixth face 32 is flatter than the fifth face 31. When the light beam is directed to the fourth lens 40 through the sixth surface 32, the beam deflection angle is small and the aberration is small.

Specifically, the ratio of the radius of the sixth surface 32 to the radius of the fifth surface 31 is 3.63 to 3.71. For example, the ratio of the radius of the sixth face 32 to the radius of the fifth face 31 is 3.63, 3.65, 3.67, 3.69 or 3.71.

Specifically, the radius r of the spherical surface corresponding to the fifth surface 31 is 64 mm-66 mm, and is selected from 64mm, 65mm and 66mm. The radius r of the sphere corresponding to the sixth surface 32 is 235 mm-240 mm, and can be 235mm, 238mm and 240mm. The larger radius r of the sphere for the sixth surface 32 facilitates the light beam passing relatively parallel through the air between the third lens 30 and the fourth lens 40 to be directed toward the fourth lens 40.

With reference to fig. 2, the half-aperture of the beam is 45mm in the fifth face 31 and 44mm in the sixth face 32, under the parameters of table 1. When the air gap passing through the third lens 30 and the fourth lens 40 reaches the fourth lens 40, the half aperture thereof is 39mm.

In some embodiments, the optical power phi of the fourth lens 40 is-0.019 to-0.015, so the fourth lens 40 has an astigmatic effect, and the absolute value of the optical power phi is larger, so that aberrations generated by the first three lenses can be well corrected.

Optionally, the fourth lens 40 has an optical power of-0.019, -0.018, -0.017 or-0.015.

In one embodiment, the refractive index n of the fourth lens 40 is 1.750-1.760, and the refractive index n is high, so that the angular deviation generated by the first three lenses can be well corrected. For example, the refractive index n of the fourth lens 40 is 1.750, 1.754, 1.755, 1.756, or 1.760.

In one embodiment, the scattering coefficient vd of the fourth lens 40 is 27.53-27.57, and the scattering coefficient vd is small, so that the aberration generated by the first three lenses can be largely corrected. For example, the scattering coefficient vd of the fourth lens 40 is 27.53, 27.55, 27.56 or 27.57.

Specifically, the edge thickness of the fourth lens 40 ranges from 3mm to 5mm, and the thickness on the optical axis O is greater than 2.0mm. Alternatively, the edge thickness of the fourth lens 40 is 5mm, and the thickness d on the optical axis O is 2mm.

Specifically, a distance d4 between the side surface of the fourth lens 40 close to the fifth lens 50 and the side surface of the fifth lens 50 close to the fourth lens 40 on the optical axis O is 38mm to 39mm, and specifically d4 is 38mm, 38.4mm, 38.6mm, or 39mm. The distance d is larger, so that the correction of the enough travel of the light beam in the air is facilitated, and the caliber of the light beam is partially increased and restored. In addition, through the adjustment of four lenses, the beam angles are relatively parallel, and enough travel is needed to adjust the caliber.

In one embodiment, the fourth lens 40 has a seventh surface 41 near the image source side and an eighth surface 42 far from the image source side, and both the seventh surface 41 and the eighth surface 42 are concave. The sphere center of the sphere where the seventh surface 41 is located at one side of the fourth lens element 40 near the image source side, and the sphere center of the sphere where the eighth surface 42 is located at one side of the fourth lens element 40 far from the image source side.

Specifically, the radius of the eighth face 42 is smaller than the radius of the seventh face 41, i.e. the seventh face 41 is flatter than the eighth face 42.

Specifically, the ratio of the radius of the eighth face 42 to the radius of the seventh face 41 is 0.35 to 0.36, such as 0.35, 0.355 or 0.36.

Specifically, the radius r of the spherical surface corresponding to the seventh surface 41 is 160 mm-165 mm, and r is selected from 160mm, 163mm and 165mm. The radius r of the sphere corresponding to the eighth face 42 is 55 mm-60 mm, and r can be selected from 55mm, 57mm, 58mm and 60mm.

Referring to fig. 2, under the parameters defined in table 1, the half-aperture of the beam is 39mm in the seventh face 41 and 33.6mm in the eighth face 42. When the air gap passing through the fourth lens 40 and the fifth lens 50 reaches the fifth lens 50, the half aperture thereof is 40.3mm.

In some embodiments, the optical power Φ of the fifth lens 50 is 0.0101 to 0.0125, which is moderate, and is slightly smaller than the absolute value of the optical power of the fourth lens 40 and larger than the optical power Φ of the first three lenses, so that the optical power of the system can be well balanced.

Optionally, the optical power Φ of the fifth lens 50 is 0.0101, 0.0110, 0.0115 or 0.0125.

In one embodiment, the refractive index n of the fifth lens 50 is 1.632-1.642. For example, the refractive index n of the fifth lens 50 is 1.632, 1.635, 1.638 or 1.642.

In one embodiment, the scattering coefficient vd of the fifth lens 50 is 55.44-55.49. For example, the scattering coefficient vd of the fifth lens 50 is 55.44, 55.47 or 55.49.

Specifically, the thickness of the edge of the fifth lens 50 ranges from 3mm to 5mm, and the thickness on the optical axis O is greater than 2.0mm. Alternatively, the edge thickness of the fifth lens 50 is 3mm, and the thickness d on the optical axis O is 20mm.

In one embodiment, a distance d5 between a side surface of the fifth lens 50 adjacent to the sixth lens 60 and a side surface of the sixth lens 60 adjacent to the fifth lens 50 on the optical axis O is 50.5mm to 51.5mm. For example, the distance d5 of the fifth lens 50 and the sixth lens 60 on the optical axis O is 50.5, 50.8, 51.0, or 51.5. In this case, the angles of the light beams are relatively parallel by the adjustment of the five lenses, and a sufficient travel distance d is required, so that the aperture thereof can be further reduced.

In one embodiment, the fifth lens 50 has a ninth surface 51 near the image source side and a tenth surface 52 far from the image source side, and both the ninth surface 51 and the tenth surface 52 are convex. That is, the center of the sphere of the ninth surface 51 is located at the side of the fifth lens element 50 away from the image source side, and the center of the sphere of the tenth surface 52 is located at the side of the fifth lens element 50 closer to the image source side.

Specifically, the radius of the tenth face 52 is smaller than the radius of the ninth face 51. The ninth surface 51 is relatively flat compared to the tenth surface 52.

Specifically, the ratio of the radius of the tenth surface 52 to the radius of the ninth surface 51 is 0.435 to 0.455, such as 0.435, 0.440, 0.445, 0.450, or 0.455.

Specifically, the radius r of the sphere corresponding to the ninth surface 51 is 170 mm-180 mm, and is selected from 170mm, 174mm, 176mm and 180mm. The radius r of the tenth surface 52 corresponding to the spherical surface is 78 mm-80 mm, and is selected from 78mm, 79mm and 80mm.

Referring to fig. 2, under the parameters of table 1, the half-aperture of the beam is 40.3mm in the ninth plane 51 and 41.5mm in the tenth plane 52. When the air gap passing through the fifth lens 50 and the sixth lens 60 reaches the sixth lens 60, the half diameter thereof is 46.0mm.

In some embodiments, the optical power phi of the sixth lens 60 is-0.0058 to-0.0048, and the optical power phi is negative, which balances the aberration generated by the fifth lens 50, so that the beam diverges outwards away from the projection lens 1, and the larger the imaging size on the farther screen 3, the smaller the optical power phi, which facilitates clear projection of the image on the farther screen 3.

Optionally, the sixth lens 60 has an optical power φ of-0.0058, -0.0054, -0.0052 or-0.0048

In some embodiments, the refractive index n of the sixth lens 60 is 1.483-1.490. For example, the refractive index n of the sixth lens 60 is 1.483, 1.485, 1.488, or 1.490.

In some embodiments, the scattering coefficient vd of the sixth lens 60 is 70.40-70.45. For example, the refractive index vd of the sixth lens 60 is 70.40, 70.42, 70.43 or 70.45.

In some embodiments, the thickness of the edge of the sixth lens 60 ranges from 3mm to 5mm, and the thickness on the optical axis O is greater than 2.0mm. Alternatively, the edge thickness of the sixth lens 60 is 5mm, and the thickness d on the optical axis O is 4mm.

In one embodiment, the second working distance Lx between the sixth lens element 60 and the image side on the optical axis O is 50 mm-56 mm. For example, the second working distance Lx is 50, 52, 54 or 56.

In one embodiment, the sixth lens 60 has an eleventh surface 61 near the image source side and a twelfth surface 62 far the image source side, the tenth surface 61 being concave and the tenth surface 62 being convex. The sphere center of the sphere of the eleventh surface 61 is located at a side of the sixth lens element 60 near the image source side, and the sphere center of the sphere of the twelfth surface 62 is located at a side of the sixth lens element 60 far from the image source side.

Specifically, the radius of the tenth face 62 is greater than the radius of the eleventh face 61, and the tenth face 62 is relatively straight.

Specifically, the ratio of the radius of the twelfth surface 62 to the radius of the eleventh surface 61 is 2.447 to 2.457. For example, the ratio of the radius of the twelfth face 62 to the radius of the eleventh face 61 is 2.447, 2.450, 2.453, or 2.457.

Specifically, the radius r of the sphere corresponding to the eleventh surface 61 is 50mm to 55mm, and is selected from 50mm, 52mm, 53mm and 55mm. The radius r of the twelfth surface 62 corresponding to the sphere is 125 mm-130 mm, and is selected from 125mm, 127mm, 129mm and 130mm. The radius of the tenth face 62 is much larger than the radius of the eleventh face 61, enabling the beams to be directed relatively parallel to the screen 3.

Referring to fig. 2, under the parameters of table 1, the half-aperture of the beam is 46mm at the eleventh surface 61 and 54mm at the tenth surface 62.

When the second working distance Lx is 2500mm, the first working distance Lw takes a value of 69.6mm under the parameter limitation of table 1, the object 2 is clearly projected on the screen 3 through the projection lens 1, and the half caliber y' on the screen 3 is 1310mm.

The field curvature refers to image field curvature, and is mainly used to represent the degree of misalignment between the intersection point of the whole light beam and an ideal image point in an optical assembly. The distortion refers to aberration of different magnification of different parts of the object 2 when the object 2 is imaged by the projection lens 1, and the distortion can cause the similarity of the object image to be worsened, but does not affect the definition of the image.

Referring to fig. 3, three light rays intersecting the abscissa in the field Qu Tu (left view) are F light (wavelength 435.1 nm), D light (wavelength 557.6 nm), and C light (wavelength 656.3 nm), respectively, from left to right. The field curvature graph shows the degree of curvature of F light, D light, and C light on a meridional image plane (T) and a sagittal image plane (S), the horizontal axis shows the amount of shift (unit: mm), and the vertical axis shows the half angle of view (unit: °). The object height radius is 42.5mm, the second working distance Lx is 2500mm, the field curvature on the screen 3 can be controlled within +/-100 mm, and the aberration is small. From the field curvature graph, the field curvature of the meridian image surface is controlled within +/-40 mm, and the field curvature of the sagittal image surface is controlled within-60 mm to +20mm, which indicates that the projection lens can excellently correct the field curvature. In the distortion graph (right graph), distortion lines of F light, D light and C light are basically overlapped, and the maximum distortion is less than 5% in the range of 0-42.5mm of object height radius y.

The point list refers to that after a plurality of light rays emitted from one point pass through an optical component, the intersection point of the light rays and an image plane is not concentrated at the same point due to aberration, so that a dispersed graph scattered in a certain range is formed, and the dispersed graph is used for evaluating the imaging quality of a projection optical system.

With reference to fig. 4, in the range of 0-42.5mm of object height radius y (i.e., object plane in the figure), the maximum speckle RMS radius of the image space is less than 4mm. In the field of photographic imaging, only the object 2 with the belt holes is cast, and the diameter of the diffuse spots meets the requirement.

Referring to fig. 5, the spot uniformity of the projection lens 1 is greater than 80% in the range of 0-42.5mm of object height radius y.

Referring to fig. 6, when the spatial frequency is 0.1mm, the object height radius range is 0-42.5mm, the value of the field of view MTF (Modulation Transfer Function ) is large, most of MTFs are larger than 0.6, and the object 2 detail reduction capability is strong.

When the second working distance Lx is 5000mm, the first working distance Lw takes a value of 68.1mm under the parameter limitation of table 1, the object 2 is clearly projected on the screen 3 through the projection lens 1, and the half caliber y' on the screen 3 is 2587mm.

Referring to fig. 7, three light rays intersecting the abscissa in the field Qu Tu (left view) are F light (wavelength 435.1 nm), D light (wavelength 557.6 nm), and C light (wavelength 656.3 nm), respectively, from left to right. The field curvature graph shows the degree of curvature of F light, D light, and C light on a meridional image plane (T) and a sagittal image plane (S), the horizontal axis shows the amount of shift (unit: mm), and the vertical axis shows the half angle of view (unit: °). The object height radius is 42.5mm, the second working distance Lx is 5000mm, the field curvature on the screen 3 can be controlled within + -5000 mm, and the aberration is small. From the field curvature graph, the field curvature of the meridian image plane (T) and the sagittal image plane (S) are controlled within-2000 mm to +1000mm, which shows that the projection lens can excellently correct the field curvature. In the distortion chart (right chart), distortion lines of the F light, the D light, and the C light substantially overlap. As can be seen from fig. 7, the maximum distortion is less than 5% for field Qu Xiao over the object height radius y of 0-42.5 mm.

Referring to fig. 8, in the range of 0-42.5mm of object height radius y, the image space maximum diffuse speckle RMS radius is less than 8mm.

Referring to fig. 9, the spot uniformity of the projection lens 1 is greater than 80% in the range of 0-42.5mm of object height radius y.

Referring to fig. 10, when the spatial frequency is 0.05mm, the object height radius ranges from 0mm to 42.5mm, the value of the field of view MTF (Modulation Transfer Function ) is large, most of MTFs are larger than 0.8, and the object 2 detail reduction capability is very strong.

In addition, the first working distance Lw is continuously adjusted, so that the object 2 is clearly projected onto the screen 3 with the second working distance Lx being larger than 5000mm, for example, lx is 10000mm, 20000mm, 25000mm and even larger, the maximum distortion of the whole field is smaller than 5%, and the maximum speckle RMS radius of the whole field of the system is smaller than 40mm; the uniformity of the system light spots is more than 85 percent; in the MTF schematic diagram, when the spatial frequency is 0.01mm, most of view fields MTF is more than 0.3, which indicates that the projection lens 1 provided by the application can realize projection imaging with high object height on the screen 3 with the second working distance Lx being more than or equal to 2500mm, and has good imaging effect.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims (10)

1. A projection lens (1), characterized in that: the projection lens (1) comprises a first lens (10), a second lens (20), a third lens (30), a fourth lens (40), a fifth lens (50) and a sixth lens (60) which are sequentially arranged from an image source side to an imaging side along an optical axis (O) at intervals, wherein the first lens (10) has positive optical power, the second lens (20) has positive optical power, the third lens (30) has positive optical power, the fourth lens (40) has negative optical power, the fifth lens (50) has positive optical power, and the sixth lens (60) has negative optical power.

2. Projection lens (1) according to claim 1, characterized in that:

the focal power of the first lens (10) is 0.0048-0.0056;

the focal power of the second lens (20) is 0.0045-0.0055;

the focal power of the third lens (30) is 0.0068-0.0076;

the focal power of the fourth lens (40) is-0.0019 to-0.015;

the focal power of the fifth lens (50) is 0.0101-0.0125;

the focal power of the sixth lens (60) is-0.0058 to-0.0048.

3. Projection lens (1) according to claim 1, characterized in that:

The first lens (10) is provided with a first surface (11) close to the image source side and a second surface (12) far away from the image source side, the first surface (11) is a plane, and the second surface (12) is a convex surface;

the second lens (20) has a third face (21) near the image source side and a fourth face (22) far from the image source side, both the third face (21) and the fourth face (22) being convex;

the third lens (30) has a fifth surface (31) close to the image source side and a sixth surface (32) far from the image source side, the fifth surface (31) being a convex surface, the sixth surface (32) being a concave surface;

the fourth lens (40) has a seventh surface (41) close to the image source side and an eighth surface (42) far from the image source side, and the seventh surface (41) and the eighth surface (42) are both concave surfaces;

the fifth lens (50) has a ninth surface (51) close to the image source side and a tenth surface (52) far from the image source side, both the ninth surface (51) and the tenth surface (52) being convex;

the sixth lens (60) has an eleventh surface (61) near the image source side and a twelfth surface (62) far from the image source side, the tenth surface (61) being concave, and the twelfth surface (62) being convex.

4. A projection lens (1) according to claim 3, characterized in that:

-the radius of the fourth face (22) is greater than the radius of the third face (21);

-the radius of the sixth face (32) is greater than the radius of the fifth face (31);

-the radius of the eighth face (42) is smaller than the radius of the seventh face (41);

the tenth face (52) has a radius smaller than the radius of the ninth face (51);

the twelfth face (62) has a radius greater than the tenth face (61).

5. Projection lens (1) according to claim 4, characterized in that:

the ratio of the radius of the fourth surface (22) to the radius of the third surface (21) is 3.47-3.51;

the ratio of the radius of the sixth surface (32) to the radius of the fifth surface (31) is 3.63-3.71;

the ratio of the radius of the eighth face (42) to the radius of the seventh face (41) is 0.35-0.36;

the ratio of the radius of the tenth surface (52) to the radius of the ninth surface (51) is 0.435 to 0.455;

the ratio of the radius of the twelfth surface (62) to the radius of the eleventh surface (61) is 2.447-2.457.

6. Projection lens (1) according to claim 1, characterized in that:

The distance between the side surface of the first lens (10) close to the second lens (20) and the side surface of the second lens (20) close to the first lens (10) on the optical axis (O) is 0.8 mm-1.2 mm;

the distance between the side surface of the second lens (20) close to the third lens (30) and the side surface of the third lens (30) close to the second lens (20) on the optical axis (O) is 0.8 mm-1.2 mm;

the distance between the side surface of the third lens (30) close to the fourth lens (40) and the side surface of the fourth lens (40) close to the third lens (30) on the optical axis (O) is 11.2 mm-11.8 mm;

the distance between the side surface of the fourth lens (40) close to the fifth lens (50) and the side surface of the fifth lens (50) close to the fourth lens (50) on the optical axis (O) is 38.0 mm-39.0 mm;

the distance between the side surface of the fifth lens (50) close to the sixth lens (60) and the side surface of the sixth lens (60) close to the fifth lens (50) on the optical axis (O) is 50.5 mm-51.5 mm.

7. Projection lens (1) according to claim 1, characterized in that:

the refractive index of the first lens (10) is 1.483-1.490;

The refractive index of the second lens (20) is 1.615-1.625;

the refractive index of the third lens (30) is 1.615-1.625;

the refractive index of the fourth lens (40) is 1.750-1.760;

the refractive index of the fifth lens (50) is 1.632-1.642;

the refractive index of the sixth lens (60) is 1.483-1.490.

8. Projection lens (1) according to claim 1, characterized in that:

the scattering coefficient of the first lens (10) is 70.40-70.45;

the scattering coefficient of the second lens (20) is 60.0-60.5;

the scattering coefficient of the third lens (30) is 60.0-60.5;

the scattering coefficient of the fourth lens (40) is 27.53-27.57;

the scattering coefficient of the fifth lens (50) is 55.44-55.49;

the scattering coefficient of the sixth lens (60) is 70.40-70.45.

9. Projection lens (1) according to claim 1, characterized in that: the thickness range of the edges of the first lens (10), the second lens (20), the third lens (30), the fourth lens (40), the fifth lens (50) and the sixth lens (60) is 3 mm-5 mm, and the thickness of the edges on the optical axis (O) is larger than 2.0mm.

10. Projection lens (1) according to any of claims 1 to 9, characterized in that: the effective focal length of the projection lens (1) is 86.45-87.50 mm; the view angle of the projection lens (1) is 50-60 degrees.