CN116125637B - Projection lens and projection device - Google Patents
Projection lens and projection deviceInfo
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- CN116125637B CN116125637B CN202211717489.5A CN202211717489A CN116125637B CN 116125637 B CN116125637 B CN 116125637B CN 202211717489 A CN202211717489 A CN 202211717489A CN 116125637 B CN116125637 B CN 116125637B
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- projection
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- projection lens
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
- G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/142—Adjusting of projection optics
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Lenses (AREA)
Abstract
本申请实施例提供了一种投影镜头及投影装置；其中，所述投影镜头由物方到像方沿同一光轴包括前透镜组、后透镜组及光阑，其中，所述光阑位于所述前透镜组与所述后透镜组之间；所述前透镜组包括最靠近物方的第一透镜；所述后透镜组包括最靠近像方的第七透镜；所述第一透镜的物方侧表面到所述第七透镜的像方侧表面的距离为L1，所述第一透镜的物方侧表面到成像面的距离为L2，L1与L2的比值满足：L1/L2≤0.6。本申请实施例提供的投影镜头，具有体积小、畸变小及解析力高的特点，利于实现整个投影装置的小型化，而且在投影镜头尺寸较小的情况下可以具有较大的后焦长度。
The embodiments of the present application provide a projection lens and a projection device; wherein the projection lens includes a front lens group, a rear lens group, and an aperture along the same optical axis from the object side to the image side, wherein the aperture is located between the front lens group and the rear lens group; the front lens group includes a first lens closest to the object side; the rear lens group includes a seventh lens closest to the image side; the distance from the object-side surface of the first lens to the image-side surface of the seventh lens is L1, and the distance from the object-side surface of the first lens to the imaging plane is L2, and the ratio of L1 to L2 satisfies: L1/L2≤0.6. The projection lens provided in the embodiments of the present application has the characteristics of small size, small distortion, and high resolution, which is conducive to miniaturization of the entire projection device, and can have a large back focal length when the projection lens size is small.
Description
Technical Field
The embodiment of the application relates to the technical field of projection imaging, in particular to a projection lens and a projection device.
Background
With the continuous change of market environment, projectors with various shapes are continuously emerging, and the performance is improved, and meanwhile, the size of the projector is smaller and more compact, so that new challenges are presented to the projection lens in the projector.
Conventional projection lenses have a large overall optical length due to the large size of the projector, which cannot meet the current modeling requirements of miniature/mini-type projectors. In addition, in order to improve the projection resolution, a vibrating mirror is added between the lens group and the light splitting device, so that the resolution of the projection lens is improved. However, due to the addition of the vibrating mirror, more structural space is reserved for the back focus of the projection lens, the back focal length of the lens is increased, the volume of the projection lens is increased, and the design difficulty of miniaturization of the projection lens is also increased.
Disclosure of Invention
The application aims to provide a novel technical scheme of a projection lens and a projection device.
In a first aspect, an embodiment of the present application provides a projection lens, where the projection lens includes a front lens group, a rear lens group, and a diaphragm along the same optical axis from an object side to an image side, and the diaphragm is located between the front lens group and the rear lens group;
The front lens group comprises a first lens closest to an object side;
the rear lens group comprises a seventh lens closest to the image side;
The distance from the object side surface of the first lens to the image side surface of the seventh lens is L1, the distance from the object side surface of the first lens to the imaging surface is L2, and the ratio of L1 to L2 is less than or equal to 0.6.
Optionally, the projection lens satisfies H/L2>0.165, wherein H is the diameter of the imaging circle of the projection lens.
Optionally, the projection lens satisfies L2/F <7.5, wherein F is the effective focal length of the projection lens.
Optionally, the projection lens satisfies D/L2<0.3, wherein D is the effective optical aperture of the first lens.
Optionally, the aperture value FNO of the projection lens is set to be less than or equal to 1.8.
Optionally, surfaces of the first lens and the seventh lens are aspheric.
Optionally, the front lens group further includes a second lens and a third lens that are adjacently disposed;
two adjacent surfaces of the second lens and the third lens are glued to form a first glued lens group, and the focal power of the first glued lens group is positive;
The first cemented lens group is positioned between the first lens and the diaphragm.
Optionally, the optical power of the first lens is negative, the two surfaces of the first lens are even aspherical surfaces, and the optical abbe number of the first lens is >50.
Optionally, the optical power of the second lens is negative, and the optical power of the third lens is positive.
Optionally, the rear lens group further comprises a fourth lens, a fifth lens and a sixth lens;
The fourth lens is arranged close to the diaphragm, the fourth lens and the fifth lens are adjacent and are in gluing arrangement, two surfaces of the fourth lens adjacent to the fifth lens are glued to form a second gluing lens group, and the focal power of the second gluing lens group is positive;
The sixth lens is positioned between the second cemented lens group and the seventh lens, and the sixth lens is a biconvex lens.
Optionally, the optical power of the seventh lens is positive, two surfaces of the seventh lens are even aspherical surfaces, and the optical abbe number of the seventh lens is >50.
Optionally, the optical power of the fourth lens is positive, and the optical power of the fifth lens is negative;
The focal power of the sixth lens is positive.
Optionally, the projection lens further comprises an optical dithering device and a light splitting device, wherein the optical dithering device and the light splitting device are sequentially arranged between the rear lens group and the imaging surface along the optical axis, and the optical dithering device comprises a vibrating mirror.
In a second aspect, the present application provides a projection apparatus. The projection device includes:
a housing, and
The projection lens is arranged on the shell.
According to the embodiment of the application, the projection lens is simple in optical structural design, small in size and high in resolution, the problem of oversized projection lens of the existing projector is effectively solved, and in addition, under the condition that the projection lens is small in size, the back focal length of the projection lens is large, and optical elements such as a vibrating mirror can be added into the back focal of the projection lens.
Other features of the present specification and its advantages will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and together with the description, serve to explain the principles of the specification.
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the present application;
FIG. 2 is a second schematic diagram of a projection lens according to an embodiment of the present application;
FIG. 3 is a diagram showing a modulation transfer function of the projection lens according to embodiment 1;
Fig. 4 is a dot column diagram of the projection lens provided in embodiment 1;
FIG. 5 is a graph showing curvature of field and distortion of a projection lens according to embodiment 1;
fig. 6 is a vertical axis color difference chart of the projection lens provided in embodiment 1;
FIG. 7 is a diagram showing a modulation transfer function of the projection lens according to embodiment 2;
Fig. 8 is a dot column diagram of the projection lens provided in embodiment 2;
FIG. 9 is a graph showing curvature of field and distortion of a projection lens according to embodiment 2;
fig. 10 is a vertical axis color difference chart of the projection lens provided in embodiment 2;
FIG. 11 is a graph of the modulation transfer function of the projection lens according to embodiment 3;
fig. 12 is a dot column diagram of the projection lens provided in embodiment 3;
FIG. 13 is a graph showing curvature of field and distortion of a projection lens according to embodiment 3;
fig. 14 is a vertical axis color difference chart of the projection lens provided in embodiment 3.
Reference numerals illustrate:
10. Front lens group 11, first lens 12, second lens 13, third lens 20, rear lens group 21, fourth lens 22, fifth lens 23, sixth lens 24, seventh lens 30, diaphragm 40, optical dithering device 50, light splitting device 60, light transmission protection device 70, image source S1, first surface S2, second surface S3, third surface S4, fourth surface S5, fifth surface S6, sixth surface S7, seventh surface S8, eighth surface S9, ninth surface S10, tenth surface S11, eleventh surface S12, twelfth surface.
Detailed Description
Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.
Techniques and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
The embodiment of the application provides a projection lens which can be applied to a projection device, has smaller volume and size and higher resolution, and meets the development trend of miniaturization of the projection device.
In the embodiment of the present application, as shown in fig. 1 and 2, the projection lens comprises a front lens group 10, a rear lens group 20 and a diaphragm 30 along the same optical axis from the object side to the image side, wherein the diaphragm 30 is located between the front lens group 10 and the rear lens group 20;
the front lens group 10 includes a first lens 11 closest to an object side;
The rear lens group 20 includes a seventh lens 24 closest to the image side;
the distance from the object side surface of the first lens 11 to the image side surface of the seventh lens 24 is L1, and the distance from the object side surface of the first lens 11 to the imaging plane is L2, and the ratio of L1 to L2 is set to be L1/L2 equal to or less than 0.6.
The projection lens provided in the above embodiment, whose corresponding optical structure is designed to be bounded by the diaphragm 30, may include two lens groups, one of which is the front lens group 10 and is disposed close to the object side, and the other of which is the rear lens group 20 and is disposed close to the image side.
Of course, other optical elements such as galvanometers, prisms, etc. may also be provided in the projection lens.
In the above embodiment, the image side refers to the side where the light source for projecting the image (or the projection screen) is located during the projection process, such as the image source 70 shown at the rightmost side in fig. 1 and 2. The object space refers to a side where a projection image is imaged on a projection surface (for example, a wall surface), such as the leftmost side in fig. 1 and 2.
The projection lens of the embodiment of the present application may further be provided with a light source, such as a display/screen, on the side of the rear lens group 20 facing away from the diaphragm 30, which may emit projection light.
The diaphragm 30 in the above embodiment is, for example, an aperture diaphragm. The diaphragm 30 may be used to control the clear aperture of the projection lens. Specifically, in the embodiment of the present application, the STOP 30 (STOP) is disposed at a suitable position between the front lens group 10 and the rear lens group 20, so that the aperture of the first lens 11 in the projection lens can be effectively compressed, and the light flux can be increased as much as possible, so that the imaging of the projection light can be clearer. Moreover, compressing the aperture of the first lens 11 is advantageous in reducing the volume and weight of the resulting projection lens, and also in reducing the cost of the projection lens to some extent.
Typically, the aperture of the diaphragm 30 is a fixed value. Of course, in order to flexibly adjust the imaging definition, the projection lens can be better adapted to the switching of high resolution and low resolution, and the diaphragm 30 can be set in a mode of adjusting the aperture size.
The projection light is emitted from the display, for example, and may be emitted from the image space toward the object space, and then sequentially passes through the rear lens group 20, the diaphragm 30 and the front lens group 10, and finally is output to the projection surface of the object space, so that a projection image may be displayed.
According to the embodiment of the application, the projection lens is simple in optical structural design, small in size and high in resolution, the problem of oversized projection lens of the existing projector is effectively solved, and in addition, under the condition that the projection lens is small in size, the back focal length of the projection lens is large, and optical elements such as a vibrating mirror can be added into the back focal of the projection lens. This reduces the overall projection lens volume and weight.
The projection lens provided by the embodiment of the application can control the ratio between the distance L1 from the object side surface of the first lens 11 to the image side surface of the seventh lens 24 and the distance L2 from the object side surface of the first lens 11 to the imaging surface to satisfy the relation L1/L2 being less than or equal to 0.6 by adjusting the optical parameters under the condition that the volume/size is designed to be smaller, thereby controlling the formed projection lens to have a large enough back focal length under the limited volume, and further, can put the added optical elements such as the galvanometer in the limited size. The resolution can be improved by adding the galvanometer into the projection lens.
If the value of L1/L2 exceeds the above range, for example, L1/L2 is 0.7 or 0.8, or even greater, the back focal length of the projection lens is relatively small, and there is not enough space for the optical elements such as the galvanometer.
Therefore, the optical parameters designed in the embodiment of the application enable the projection lens to have larger back focal length under the condition of ensuring small size, and the galvanometer can be introduced under the condition of not influencing the small-size design of the projection lens so as to improve the resolution of the projection lens. The final formed projection lens has the advantages of small volume, light weight and high resolution.
In some examples of the application, the projection lens satisfies H/L2>0.165, where H is the diameter of the imaging circle of the projection lens.
Generally, as the size/volume of the projection lens is reduced, the size of the micro-display chip (i.e., the light emitting chip) is also smaller than 0.2 inch, which may result in a smaller diameter H of the image circle of the projection lens, thereby affecting the field angle and imaging quality of the projection lens.
In the above example of the present application, through a brand new design of optical parameters, the dimension of the diameter H of the imaging circle of the projection lens can be designed to be as large as possible under the condition that the dimension of the projection lens is limited, so that a Digital Micromirror Device (DMD) or other light emitting chips of 0.2 inch to 0.3 inch, for example, can be matched, which is beneficial to expanding the field angle and imaging quality of the projection lens.
The projection lens may further include an IMAGE source 70 (IMAGE), where the IMAGE source 70 is a micro-display chip such as a DMD or LCOS. In particular, the image source 70 is located on the side of the rear lens group 20 facing away from the diaphragm 30, and the image source 70 may be used to project projection light.
The projection lens provided by the embodiment of the application has the advantages that the formed optical structure can be matched with a digital micromirror element (Digital Micromirror Device, DMD) with the size of 0.2 inch-0.3 inch for use, so that the projection display effect is better, and the size of the whole projection lens is not increased. The projection lens provided by the embodiment of the application has small size and more compact structure, and is beneficial to realizing the miniaturization of the projection device.
The DMD consists of a plurality of digital micro-mirror elements which are arranged in a matrix, and each micro-mirror can deflect and lock in the positive and negative directions when in operation, so that light rays are projected in a given direction and swing at the frequency of tens of thousands of hertz, and the light rays from the illumination light source enter a projection lens to be imaged on a screen through the turning reflection of the micro-mirror. The DMD has the advantage of having a high resolution, the signal does not need digital-to-analog conversion and the like.
In some examples of the application, the projection lens satisfies L2/F <7.5, where F is the effective focal length of the projection lens.
By controlling the ratio of the distance L2 from the object side surface (see the first surface S1 shown in fig. 2) of the first lens 11 to the imaging surface in the projection lens to the effective focal length F of the projection lens within the above range, the radius of curvature and focal length of the first lens 11 can be controlled to be reduced, so that the size and weight of the first lens 11 can be appropriately reduced, thereby facilitating the reduction of the volume and weight of the entire projection lens, and ensuring the better quality of projection imaging.
For example, the first lens 11 is designed as a meniscus type aspherical lens. The first lens 11 is a negative lens, and the distortion and the field curvature phase difference can be effectively reduced when the projection lens is applied to the embodiment of the application.
In the use state of the projection lens, the first lens 11 is the lens at the forefront end of the projection lens, and the aperture of the front end of the projection lens is compressed along with the reduction of the size of the first lens 11.
In some examples of the application, the projection lens satisfies D/L2<0.3, where D is the effective optical aperture of the first lens 11.
The optical parameter design range in the above example also controls to reduce the aperture and focal length of the first lens 11 to some extent, while ensuring the resolution of the final projection imaging. This is advantageous in that the formed projection lens has excellent imaging effect while being small in volume and light in weight.
In some examples of the present application, the aperture value FNO of the projection lens is set to FNO 1.8 or less.
The aperture value FNO of the projection lens is used for controlling the light quantity.
Specifically, the smaller the FNO value, the more the light passing amount. That is, the aperture value FNO affects the imaging brightness of the projection lens.
In the example of the present application, the aperture value FNO of the projection lens is designed to be not more than 1.8, which can ensure that the brightness of the outgoing light of the whole projection lens is higher and the light energy loss is less. The brightness of the finally projected picture is high, and the visual experience is good.
If the aperture value FNO of the projection lens is designed to be relatively large, for example, 2.0, the brightness of the projected image is low, and the requirement of the image quality of the projected image cannot be met.
In some examples of the present application, as shown in fig. 1 and 2, the surfaces of the first lens 11 and the seventh lens 24 are provided as aspherical surfaces.
In the projection lens, the first lens 11 is designed to be the lens closest to the object, and the first lens 11 can be designed to be an aspheric negative lens, so that distortion and curvature of field can be effectively reduced, and the front end caliber of the projection lens can be compressed.
In the projection lens, the seventh lens 24 is designed as a lens closest to the image side, and the aspheric surface design is adopted to effectively correct the residual aberration, compress the total optical length of the projection lens, and ensure the image quality of the projected image.
Alternatively, referring to fig. 2, the two surfaces of the first lens 11, for example, the first surface S1 and the second surface S2 are both provided as even aspherical surfaces, wherein the first surface S1 is an object side surface of the first lens 11, and the second surface S2 is an image side surface of the first lens 11.
Alternatively, referring to fig. 2, both surfaces of the seventh lens 24, for example, an eleventh surface S11 and a twelfth surface S12 are each provided as an even aspherical surface, wherein the eleventh surface S11 is an object-side surface of the seventh lens 24, and the twelfth surface S12 is an image-side surface of the seventh lens 24.
Wherein the surface patterns of the first lens 11 and the seventh lens 24 are even aspherical surface patterns, which satisfy the following formula:
Z＝cy2/{1+[1-(1+k)c2y2]1/2}+a1y2+a2y4+a3y6+a4y8+a5y10+a6y12+a7y14+a8y16;
Wherein c is the curvature corresponding to the radius, y is the radial coordinate (the unit is the same as the unit of the lens length), and k is the conic coefficient.
When k < -1, the surface profile is hyperbolic. When k= -1, the surface profile is parabolic. When k is between-1 and 0, the planar curve is elliptical. When k=0, the face shape is circular. When k >0, the surface shape is an oblate curve. a 1 to a 8 respectively represent coefficients corresponding to the respective radial coordinates, and the shape and size of the aspherical surface of the lens imaging optical surface can be precisely set by the above parameters.
In some examples of the present application, referring to fig. 1 and 2, the front lens assembly 10 may further include a second lens 12 and a third lens 13 disposed adjacent to each other in addition to the first lens 11, wherein two surfaces of the second lens 12 and the third lens 13 adjacent to each other are glued to form a first glued lens assembly, the optical power of the first glued lens assembly is positive, and the first glued lens assembly is located between the first lens 11 and the diaphragm 30.
That is, in the example of the present application, the front lens group 10 may include three lenses, namely, a first lens 11, a second lens 12, and a third lens 13, which are sequentially disposed along the same optical axis.
In the front lens group 10 of the above example, the second lens 12 and the third lens 13 are glued, the first glued lens group is designed to be placed on one side of the diaphragm 30, the second lens 12 and the third lens 13 cooperate with each other to adjust the optical incident angle and reduce the optical distortion, and at the same time, the gluing of the two can effectively reduce the chromatic aberration.
Referring to fig. 2, the fourth surface S4 is formed by the cemented surface of the second lens 12 and the third lens 13, which form a first cemented lens group having positive optical power. For example, the second lens 12 is a negative lens, which can further correct the distortion of the incident light, the third lens 13 is a positive lens, which can correct the curvature of field aberration, and the second lens 12 and the third lens 13 are glued by positive and negative lenses, which can reduce the vertical chromatic aberration and the axial chromatic aberration of the projection lens by combining the optical abbe numbers in terms of materials.
In addition, the required structural space can be effectively reduced through lens gluing, and the volume of the projection lens is reduced.
Alternatively, referring to fig. 1, the optical power of the first lens 11 is negative, both surfaces of the first lens 11 are even aspherical surfaces, and the optical abbe number of the first lens 11 is >50.
For example, referring to fig. 2, the first lens 11 is a meniscus type aspheric lens having negative power, the first surface S1 is a convex surface, and the second surface S2 is a concave surface. The first lens 11 can rapidly deflect light using a meniscus negative lens. The first lens 11 is made of a lens material with an optical abbe number >50, which is beneficial to reducing chromatic aberration. The aspheric surface shape can effectively correct optical distortion and reduce the caliber of the front end of the projection lens.
The material of the first lens 11 may be, for example, a glass material. This is advantageous in further reducing distortion, improving scratch resistance of the lens, and improving temperature stability.
Optionally, the optical power of the second lens 12 is negative, and the optical power of the third lens 13 is positive.
For example, referring to fig. 2, the second lens 12 is a spherical lens having negative optical power, and a surface thereof close to the object side is a third surface S3, and a surface thereof close to the image side is a fourth surface S4.
Specifically, referring to fig. 2, the third lens 13 is a spherical lens with positive optical power, and the surface of the third lens close to the object side is glued with the fourth surface S4 of the second lens 12, and the surface of the third lens close to the image side is the fifth surface S5. It is also understood that the surface where the second lens 12 and the third lens 13 are glued forms the fourth surface S4.
In the projection lens provided by the embodiment of the present application, the second lens 12 and the third lens 13 may form a first cemented lens group having positive optical power. The second lens 12 is a negative lens, and can further correct the distortion of the incident light. The third lens 13 is a positive lens, and can correct curvature of field. In this way, the second lens 12 and the third lens 13 are glued by positive and negative lenses, and the vertical axis chromatic aberration and the axial chromatic aberration of the projection lens can be reduced by adopting a mode of combining the optical abbe number and the optical abbe number in terms of materials.
In some examples of the present application, referring to fig. 1 and 2, the rear lens group 20 includes, in addition to the aforementioned seventh lens 24, a fourth lens 21, a fifth lens 22 and a sixth lens 23, wherein the fourth lens 21 is disposed close to the diaphragm 30, the fourth lens 21 and the fifth lens 22 are disposed adjacently and are glued, two surfaces of the fourth lens 21 and the fifth lens 22 adjacent to each other are glued to form a second glued lens group, the optical power of the second glued lens group is positive, the sixth lens 23 is disposed between the second glued lens group and the seventh lens 24, and the sixth lens 23 is a biconvex lens.
In the projection lens, the diaphragm 30 is designed to be positioned between the third lens 13 and the fourth lens 21, and the optical effective aperture of the first lens 11 is reduced while maintaining a large aperture light transmission. Two sides of the diaphragm 30 are respectively provided with a glued lens group. Specifically, a first cemented lens group formed by the second lens 12 and the third lens 13 cemented together is provided on one side of the diaphragm 30, and a second cemented lens group formed by the fourth lens 21 and the fifth lens cemented together is provided on the other side of the diaphragm 30.
The fourth lens 21 and the fifth lens 22 are glued to effectively reduce optical spherical aberration and axial chromatic aberration.
For example, the sixth lens 23 is a biconvex positive lens, and deflects the light so that the projection lens emits light as a telecentric light path, which can meet the requirement of projection light.
For example, the seventh lens 24 is an aspherical lens, which can effectively correct residual aberration and compress the total optical length of the projection lens, so as to ensure the quality of the projected image.
Through the combination, the formed projection lens can meet the design trend of miniaturization and light weight of the projector while meeting high resolution and small distortion, and meanwhile, the optical total length of the projection lens is effectively reduced.
Optionally, the focal power of the seventh lens 24 is positive, the two surfaces of the seventh lens 24 are even aspherical surfaces, and the optical abbe number of the seventh lens 24 is >50.
Referring to fig. 2, the seventh lens 24 is, for example, a biconvex aspheric lens having positive power, the surface of the seventh lens 24 near the object side is an eleventh surface S11, the eleventh surface S11 is a convex surface, the surface of the seventh lens 24 near the image side is a twelfth surface S12, and the twelfth surface S12 is also a convex surface. The seventh lens 24 can be used to converge light, correct residual aberration, and compress the volume of the projection lens, and the use of aspheric surfaces can greatly enhance the correction capability.
The seventh lens 24 is made of a lens material with an optical abbe number >50 to further reduce chromatic aberration.
In addition, the seventh lens 24 is made of glass material, which can further improve the aberration correction capability, greatly improve the temperature stability of the lens, and improve the thermal deficiency-focus phenomenon.
Alternatively, the optical power of the fourth lens 21 is positive, the optical power of the fifth lens 22 is negative, and the optical power of the sixth lens 23 is positive.
Referring to fig. 2, the fourth lens 21 is, for example, a meniscus spherical lens with positive power, and includes a sixth surface S6 near the object side and a seventh surface S7 near the image side, where the sixth surface S6 may be a concave surface and the seventh surface S7 may be a convex surface.
The fifth lens 22 is, for example, a meniscus spherical lens with negative focal power, and includes a surface close to the object side, which is a concave surface glued with the seventh surface S7 of the fourth lens 21, and the fifth lens 22 further includes an eighth surface S8 close to the image side, and the eighth surface S8 is a convex surface.
The fourth lens 21 and the fifth lens 22 are cemented to form a cemented lens having positive optical power, which can effectively reduce spherical aberration and axial chromatic aberration, and reduce curvature of field aberration.
The sixth lens 23 is, for example, a biconvex spherical lens having positive optical power, and includes a ninth surface S9 near the object side and a tenth surface S10 near the image side, and both the ninth surface S9 and the tenth surface S10 are designed to be convex. The sixth lens 23 can turn and converge light, reduce the angle of the outgoing light of the projection lens, improve telecentricity, and correct coma and astigmatic aberration. In addition, the sixth lens 23 is made of a lens material with an optical abbe number >50, so as to reduce chromatic aberration.
In some examples of the present application, the projection lens further includes an optical dithering device 40 and a light splitting device 50, and the optical dithering device 40 and the light splitting device 50 are sequentially arranged between the rear lens group 20 and the imaging plane along the optical axis, wherein the optical dithering device 40 includes a galvanometer.
The projection lens provided by the embodiment of the application has enough structural space in the back focal part, and the optical dithering device 40 is introduced into the rear focal part, and the optical dithering device 40 can improve the resolution of the projection lens during operation. It should be noted that, in the case of adding the optical dithering device 40, the optical scheme of the present application can reduce the volume of the projection lens, and has good projection imaging quality.
Furthermore, the light splitting means 50 (PRISM) is, for example, a TIR or RTIR PRISM, which is equal in optical path length.
Referring to fig. 1 and 2, a light-transmitting protective device 60 may be further provided between the spectroscopic device 50 and the image source 70. Optionally, the light-transmitting protective device 60 is a protective glass.
The IMAGE source 70 (IMAGE) is a micro-display chip such as DMD or LCOS.
In one specific example of the present application, the projection lens sequentially comprises a first lens 11, a second lens 12, a third lens 13, a diaphragm 30, a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an optical dithering device 40, a beam splitting device 50, a light transmission protection device 60 and an image source 70 along the same optical axis from the object side to the image side, wherein:
the first lens 11 is a meniscus type aspherical lens having negative optical power, and an optical abbe number >50;
the second lens 12 is a spherical glass lens with negative optical power, and the optical Abbe number is >50;
the third lens 13 is a spherical glass lens with positive focal power, and the optical Abbe number is <35;
the fourth lens 21 is a meniscus spherical glass lens with positive focal power, and the optical Abbe number is more than 50;
The fifth lens 22 is a meniscus type spherical glass lens having negative optical power;
The sixth lens 23 is a biconvex spherical glass lens with positive focal power, and has an optical abbe number >50;
the seventh lens 24 is a biconvex aspherical lens having positive optical power, and has an optical abbe number >50;
the second lens 12 and the third lens 12 are cemented into a first cemented lens group having positive optical power, the fourth lens 21 and the fifth lens 22 are cemented into a second cemented lens group having positive optical power;
the optical dithering device 40 is a galvanometer;
the distance from the object side surface of the first lens 11 to the image side surface of the seventh lens 24 is L1, the distance from the object side surface of the first lens 11 to the imaging surface is L2, and the ratio of L1 to L2 is L1/L2 less than or equal to 0.6;
the projection lens satisfies that H/L2 is more than 0.165, wherein H is the diameter of an imaging image circle of the projection lens;
the projection lens satisfies L2/F <7.5, wherein F is the effective focal length of the projection lens;
the projection lens satisfies D/L2<0.3, wherein D is the effective optical caliber of the first lens;
the aperture value FNO of the projection lens is set to be less than or equal to 1.8.
The projection lens provided by the application adopts the spherical lens, the aspherical lens and the glued lens to be matched with each other for use, so that the total length of the projection lens is effectively reduced on the premise of meeting the requirement of optical performance, and the formed whole projection lens has the characteristics of small volume, small distortion and high resolving power.
To further optimize the performance of the projection lens, three examples are described below.
Example 1
The projection lens provided in embodiment 1 of the present application sequentially includes, along the same optical axis from an object side to an image side, a first lens 11, a second lens 12, a third lens 13, a diaphragm 30, a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an optical dithering device 40, a light splitting device 50, a light transmission protection device 60 and an image source 70, wherein the relevant parameters of each lens are shown in table 1:
TABLE 1
The aspherical coefficients of the first lens 11 and the seventh lens 24 in embodiment 1 are shown in table 2:
TABLE 2
The main parameters in example 1 are shown in table 3:
TABLE 3 Table 3
| L1(mm) | L2(mm) | H(mm) | F(mm) | D(mm) | FNO. | L1/L2 | H/L2 | L2/F | D/L2 |
| 25.51 | 43.813 | 8 | 6.3 | 11.6 | 1.7 | 0.58 | 0.182 | 6.95 | 0.265 |
The MTF curve, the dot column, the field curvature distortion, and the vertical axis chromatic aberration of the projection lens provided in this embodiment 1 are shown in fig. 3, 4,5, and 6, respectively.
The image source pixel size employed in this example 1 was 5.4 μm, corresponding to a design resolution of 93lp/mm.
As can be seen from the MTF graph shown in FIG. 3, the MTF of the center view field of the projection lens provided in the embodiment 1 is greater than 0.6 at 93lp/mm, and the MTF of the maximum view field is greater than 0.4, so that the design requirement of the light emitting chip MTF is greater than 0.3 can be met.
Fig. 4 is a point diagram of the projection lens according to embodiment 1, wherein the RMS radius is 4.1 μm, and within 1 pixel, the resolution is guaranteed to be sharp.
Fig. 5 is a field curvature distortion chart of the projection lens according to embodiment 1, wherein the optical distortion is less than or equal to 1% in the field curvature distortion, and the imaging picture is not significantly deformed.
Fig. 6 is a vertical chromatic aberration diagram of the projection lens proposed in embodiment 1, wherein the vertical chromatic aberration is maximum 3 μm, and the image has no color edge phenomenon within 1 pixel.
This embodiment 1 is applicable to a Digital Micromirror Device (DMD) having an image source 70 of 0.23 inch, a projection lens throw ratio of 1.2, and an aperture value FNO of 1.7.
Example 2
The projection lens provided in embodiment 2 of the present application sequentially includes, along the same optical axis from the object side to the image side, a first lens 11, a second lens 12, a third lens 13, a diaphragm 30, a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an optical dithering device 40, a spectroscopic device 50, a light-transmitting protection device 60, and an image source 70, wherein the parameters related to each lens are shown in table 4:
TABLE 4 Table 4
The aspherical coefficients of the first lens 11 and the seventh lens 24 in embodiment 2 are shown in table 5:
TABLE 5
The main parameters in example 2 are shown in table 6:
TABLE 6
| L1(mm) | L2(mm) | H(mm) | F(mm) | D(mm) | FNO | L1/L2 | H/L2 | L2/F | D/L2 |
| 22.59 | 40.343 | 7 | 5.66 | 10 | 1.7 | 0.56 | 0.173 | 7.13 | 0.247 |
The MTF curve, the dot column, the field curvature distortion, and the vertical axis chromatic aberration of the projection lens provided in this embodiment 2 are shown in fig. 7,8, 9, and 10, respectively.
The image source pixel size employed in this example 2 was 5.4 μm, corresponding to a design resolution of 93lp/mm.
As can be seen from the MTF graph shown in FIG. 7, the MTF of the center view field of the projection lens provided in the embodiment 2 is greater than 0.55 at 93lp/mm, and the MTF of the maximum view field is greater than 0.4, so that the design requirement of the light emitting chip MTF is greater than 0.3 can be met.
Fig. 8 is a dot column diagram of the projection lens according to embodiment 2, wherein the RMS radius is 3.7 μm, and within 1 pixel, the resolution is guaranteed to be sharp.
Fig. 9 is a graph of field curvature distortion of the projection lens according to embodiment 2, wherein optical distortion is less than or equal to 1% in field curvature distortion, and the imaging picture is not significantly deformed.
Fig. 10 is a vertical chromatic aberration diagram of the projection lens proposed in embodiment 2, wherein the maximum vertical chromatic aberration is 3.3 μm, and the image has no color edge phenomenon within 1 pixel.
This embodiment 2 is applicable to a Digital Micromirror Device (DMD) having an image source 70 of 0.2 inch, a projection lens throw ratio of 1.2, and an aperture value FNO of 1.7.
Example 3
The projection lens provided in embodiment 3 of the present application sequentially includes, along the same optical axis from an object side to an image side, a first lens 11, a second lens 12, a third lens 13, a diaphragm 30, a fourth lens 21, a fifth lens 22, a sixth lens 23, a seventh lens 24, an optical dithering device 40, a spectroscopic device 50, a light-transmitting protection device 60, and an image source 70, wherein the parameters related to each lens are shown in table 7:
TABLE 7
The aspherical coefficients of the first lens 11 and the seventh lens 24 in embodiment 3 are shown in table 8:
TABLE 8
The main parameters in example 3 are shown in table 9:
TABLE 9
| L1(mm) | L2(mm) | H(mm) | F(mm) | D(mm) | FNO | L1/L2 | H/L2 | L2/F | D/L2 |
| 25.97 | 44.26 | 8 | 5.96 | 11.5 | 1.8 | 0.587 | 0.181 | 7.43 | 0.26 |
The MTF curve, the dot column, the field curvature distortion, and the vertical axis chromatic aberration of the projection lens provided in this embodiment 3 are shown in fig. 11, 12, 13, and 14, respectively.
The image source pixel size employed in this example 3 was 5.4 μm, corresponding to a design resolution of 93lp/mm.
As can be seen from the MTF graph shown in FIG. 11, the MTF of the center view field of the projection lens proposed in the embodiment 3 is greater than 0.58 at 93lp/mm, and the MTF of the maximum view field is greater than 0.4, so that the design requirement of the light emitting chip MTF is greater than 0.3 can be met.
Fig. 12 is a dot column diagram of the projection lens according to embodiment 3, wherein the RMS radius is 5 μm and within 1 pixel, so as to ensure resolution sharpness.
Fig. 13 is a graph showing field curvature distortion of the projection lens according to embodiment 3, wherein optical distortion is less than or equal to 1% in field curvature distortion, and the image is not significantly distorted.
Fig. 14 is a vertical chromatic aberration diagram of the projection lens proposed in this embodiment 3, wherein the maximum vertical chromatic aberration is 2.9 μm, and the image has no color edge phenomenon within 1 pixel.
This embodiment 3 is applicable to a Digital Micromirror Device (DMD) having an image source 70 of 0.23 inch, a projection lens throw ratio of 1.15, and an aperture value FNO of 1.8.
The embodiment of the application also provides a projection device, which comprises a shell and the projection lens, wherein the projection lens is arranged on the shell.
The specific structure of the projection lens can be seen from the above embodiments.
The projection device of the present application adopts the projection lens of all the embodiments, so that the projection device has at least all the advantages brought by the technical solutions of the embodiments, and will not be described in detail herein.
The foregoing embodiments mainly describe differences between the embodiments, and as long as there is no contradiction between different optimization features of the embodiments, the embodiments may be combined to form a better embodiment, and in consideration of brevity of line text, no further description is given here.
While certain specific embodiments of the application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.
Claims (13)
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102879888A (en) * | 2011-07-15 | 2013-01-16 | 亚洲光学股份有限公司 | Fixed focus projection lens |
| CN110579927A (en) * | 2019-10-09 | 2019-12-17 | 安徽仁和光电科技有限公司 | Small low-F-number high-definition projection lens |
| CN216118220U (en) * | 2021-10-28 | 2022-03-22 | 歌尔光学科技有限公司 | Projection lens group and head-up display system |
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| CN110426815B (en) * | 2019-07-19 | 2021-05-18 | 杭州有人光电技术有限公司 | Small low-F-number high-definition projection lens |
| CN110673306B (en) * | 2019-10-09 | 2021-07-30 | 安徽仁和光电科技有限公司 | Small-size full high definition short-focus projection lens |
| CN112379520B (en) * | 2020-11-06 | 2022-11-15 | 歌尔光学科技有限公司 | Projection lens and be provided with on-vehicle HUD of this projection lens |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102879888A (en) * | 2011-07-15 | 2013-01-16 | 亚洲光学股份有限公司 | Fixed focus projection lens |
| CN110579927A (en) * | 2019-10-09 | 2019-12-17 | 安徽仁和光电科技有限公司 | Small low-F-number high-definition projection lens |
| CN216118220U (en) * | 2021-10-28 | 2022-03-22 | 歌尔光学科技有限公司 | Projection lens group and head-up display system |
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