Projection lens and projection equipment
By designing the lens combination of the back and front groups in the LCOS projection lens, the problem of poor back focus and imaging quality in the HUD equipment is solved, and a projection lens with low cost and high imaging quality is achieved, which improves the cost-effectiveness of the projection lens.
Patent Information
- Application Number
- CN202421250232.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-31
- Publication Date
- 2025-01-14
- Estimated Expiration
- 2034-05-31
AI Technical Summary
The existing LCOS projection lenses have problems in HUD devices that require compression of the back focus of the lens, poor imaging quality and high cost.
A projection lens is designed, including a rear group and a front group arranged in sequence from the object side to the image side along the optical axis direction. The rear group achieves smooth light transition and chromatic aberration correction through continuously arranged positive power lenses and glued lenses. The group consists of positive and negative power lenses to form a negative total power, which is used to correct distortion and field curves, reduce the use of aspherical lenses, and reduce costs.
A projection lens with high imaging quality is achieved with large air rear focals, reducing costs and improving cost-effectiveness.
Smart Images
Figure CN222354127U_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of projection lenses, and in particular, relates to a projection lens and a projection device. Background Art
[0002] Common projection technologies mainly include Digital Light Processing (DLP) technology, Liquid Crystal on Silicon (LCOS) technology and Liquid Crystal Display (LCD) technology; among them, DLP projection lenses and LCOS projection lenses are widely used in Head Up Display (HUD) devices.
[0003] However, when existing LCOS projection lenses are applied to HUD devices, there are generally problems such as the need to compress the lens back focus, poor image quality, and high cost. Utility Model Content
[0004] In view of this, an embodiment of the present application provides a projection lens and a projection device, which aims to solve the problems of the need to compress the lens back focus, poor imaging quality and high cost when the existing LCOS projection lens is applied to HUD devices.
[0005] A first aspect of an embodiment of the present application provides a projection lens, comprising a rear group and a front group arranged in sequence from an object side to an image side along an optical axis direction;
[0006] The rear group includes a first positive power lens and a second positive power lens arranged in series and a first cemented lens and a second cemented lens arranged in series;
[0007] The front group includes a first aberration correction unit and a second aberration correction unit which are arranged in series. The first aberration correction unit and the second aberration correction unit are both composed of a combination of positive and negative optical power lenses. The total optical power of the front group is negative.
[0008] In one embodiment, the first cemented lens includes a third negative power lens and a fourth positive power lens, and the second cemented lens includes a fifth positive power lens and a sixth negative power lens;
[0009] The refractive indexes of the fourth positive power lens and the fifth positive power lens are both lower than or equal to the first refractive index, the refractive index of at least one of the third negative power lens and the sixth negative power lens is higher than or equal to the second refractive index, and the first refractive index is lower than the second refractive index;
[0010] The Abbe numbers of the fourth positive power lens and the fifth positive power lens are both higher than or equal to the first Abbe number, the Abbe number of at least one of the third negative power lens and the sixth negative power lens is lower than or equal to the second Abbe number, and the first Abbe number is higher than the second Abbe number.
[0011] In one embodiment, the rear group further includes a seventh positive power lens, and the seventh positive power lens is located between the second cemented lens and the first aberration correction unit;
[0012] Alternatively, the rear group further includes a stop, and the stop is located between the second cemented lens and the first aberration correction unit;
[0013] Alternatively, the rear group further includes a seventh positive power lens and an aperture, and the seventh positive power lens and the aperture are sequentially located between the second cemented lens and the first aberration correction unit.
[0014] In one embodiment, the first aberration correction unit includes an eighth positive power lens and a ninth negative power lens, and the second aberration correction unit includes a tenth negative power lens and an eleventh positive power lens;
[0015] At least one of the ninth negative power lens and the tenth negative power lens has a refractive index lower than or equal to the first refractive index and an Abbe number higher than or equal to the first Abbe number.
[0016] In one embodiment, the ninth negative power lens is biconcave, and the tenth negative power lens is meniscus.
[0017] In one embodiment, the first refractive index is equal to 1.65, and the second refractive index is equal to 1.80;
[0018] The first Abbe number is equal to 60, and the second Abbe number is equal to 35.
[0019] In one embodiment, all lenses in the projection lens are spherical lenses.
[0020] In one embodiment, the projection lens further includes a display chip, a quarter wave plate and a polarizing plate which are located on the object side and arranged in sequence.
[0021] A second aspect of an embodiment of the present application provides a head-up display device, including the projection lens provided by the first aspect.
[0022] In one embodiment, the projection device is a head-up display device.
[0023] In the projection lens provided in the first aspect of the embodiment of the present application, the first positive power lens and the second positive power lens of the rear group are used to achieve a smooth transition of the power and light of the rear group, reduce the incident angle of the light on the lens surface, and reduce the spherical aberration by sharing the deflection angle of the light; the first cemented lens and the second cemented lens of the rear group can correct chromatic aberration, thereby reducing the difficulty of aberration correction of the front group, and reducing the material and refractive index requirements for other lenses, thereby reducing costs, so that the projection lens as a whole has a higher cost performance; the two groups of aberration correction units composed of positive and negative power lenses in the front group are used to correct distortion and field curvature to obtain a balance between distortion correction and field aberration correction, minimize the use of aspherical lenses, and thus reduce costs; the total power of the front group is negative, which can lengthen the back focus of the entire projection lens.
[0024] The projection device provided in the second aspect of the embodiment of the present application can obtain a large air back focus, high imaging quality and low cost by adopting the projection lens provided in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0026] Figure 1 is a schematic diagram of the first structure of the projection lens provided in the embodiment of the present application;
[0027] Figure 2 This is a schematic diagram of the first structure of the rear group provided in the embodiment of the present application;
[0028] Figure 3 is a schematic diagram of a second structure of a projection lens provided in an embodiment of the present application;
[0029] Figure 4 It is a second structural schematic diagram of the rear group provided in the embodiment of the present application;
[0030] Figure 5 is a third structural schematic diagram of the projection lens provided in the embodiment of the present application;
[0031] Figure 6 This is a third structural schematic diagram of the rear group provided in the embodiment of the present application;
[0032] Figure 7 is a fourth structural schematic diagram of a projection lens provided in an embodiment of the present application;
[0033] Figure 8This is a schematic diagram of the fourth structure of the rear group provided in the embodiment of the present application;
[0034] Fig. 9 It is a schematic diagram of the structure of the front group provided in the embodiment of the present application;
[0035] Fig.10 is a fifth structural schematic diagram of a projection lens provided in an embodiment of the present application;
[0036] Fig.11 is a schematic diagram of a projection lens and its projection surface provided in an embodiment of the present application;
[0037] Fig.12 is a schematic diagram of a modulation transfer function at a display chip provided in an embodiment of the present application;
[0038] Figure Number:
[0039] 100-projection lens;
[0040] 101-display chip;
[0041] 102-Protective glass;
[0042] 103-1 / 4 wave plate;
[0043] 104- polarizer;
[0044] 110-rear group, 111-first positive power lens, 112-second positive power lens, 113-third negative power lens, 114-fourth positive power lens, 115-fifth positive power lens, 116-sixth negative power lens, 117-seventh positive power lens, 118-aperture;
[0045] 120 - front group, 121 - eighth positive power lens, 122 - ninth negative power lens, 123 - tenth negative power lens, 124 - eleventh positive power lens. DETAILED DESCRIPTION
[0046] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.
[0047] The term "comprising" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method or system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. In addition, the terms "first", "second" and "third" etc. are used to distinguish different objects, rather than to describe a specific order.
[0048] like Figure 1 or Figure 2 As shown, this embodiment provides a projection lens 100, comprising a rear group 110 and a front group 120 arranged in sequence from the object side to the image side along the optical axis direction;
[0049] The rear group 110 includes a first positive power lens 111 and a second positive power lens 112 arranged in series, and a first cemented lens and a second cemented lens arranged in series;
[0050] The front group 120 includes a first aberration correction unit and a second aberration correction unit which are arranged in series. The first aberration correction unit and the second aberration correction unit are both composed of a combination of positive and negative optical power lenses. The total optical power of the front group 120 is negative.
[0051] In application, a large-power lens group with a total optical focal length that is higher than the optical focal length of any one of the first positive-power lens 111 and the second positive-power lens 112 is formed together, so that a smooth transition of the optical focal length and light of the rear group 110 can be achieved, the incident angle of light on the lens surface can be reduced, and spherical aberration can be reduced by sharing the light deviation angle.
[0052] like Figure 2 As shown, in one embodiment, the first cemented lens includes a third negative power lens 113 and a fourth positive power lens 114, and the second cemented lens includes a fifth positive power lens 115 and a sixth negative power lens 116;
[0053] The refractive index (index of refraction, Nd) of the fourth positive power lens 114 and the fifth positive power lens 115 is lower than or equal to the first refractive index, the refractive index of at least one of the third negative power lens 113 and the sixth negative power lens 116 is higher than or equal to the second refractive index, and the first refractive index is lower than the second refractive index;
[0054] The Abbe numbers (Abbe, Vd) of the fourth positive power lens 114 and the fifth positive power lens 115 are both higher than or equal to the first Abbe number, the Abbe number of at least one of the third negative power lens 113 and the sixth negative power lens 116 is lower than or equal to the second Abbe number, and the first Abbe number is higher than the second Abbe number.
[0055] In application, the third negative power lens 113 and the fourth positive power lens 114 are bonded to form a first bonded lens, and the fifth positive power lens 115 and the sixth negative power lens 116 are bonded to form a second bonded lens. The first bonded lens and the second bonded lens can correct chromatic aberration, thereby reducing the difficulty of aberration correction of the front group 120 and reducing the material and refractive index requirements for other lenses, thereby reducing costs, so that the projection lens 100 as a whole has a higher cost-effectiveness.
[0056] In application, the fourth positive power lens 114 and the fifth positive power lens 115 have relatively low refractive index, and at least one of the third negative power lens 113 and the sixth negative power lens 116 has relatively high refractive index;
[0057] The fourth positive power lens 114 and the fifth positive power lens 115 have relatively high Abbe numbers, and at least one of the third negative power lens 113 and the sixth negative power lens 116 has a relatively low Abbe number;
[0058] The first refractive index, the second refractive index, the first Abbe number, and the second Abbe number can be set according to actual needs as long as the above relative size relationships are satisfied.
[0059] In one embodiment, the first refractive index is equal to 1.65 and the second refractive index is equal to 1.80;
[0060] The first Abbe number is equal to 60 and the second Abbe number is equal to 35.
[0061] In application, the first cemented lens and the second cemented lens can be split into a double lens with a suitable air gap, and the contour shape of each single lens in the double lens is kept similar to that of each corresponding single lens in the original cemented lens. Each positive focal power lens can also be split into two positive focal power lenses with equal functions. The specific composition of each lens is not limited in the embodiments of the present application.
[0062] In application, since the first cemented lens and the second cemented lens are composed of a combination of positive and negative optical power lenses, the internal friction of the optical power makes the cemented lens as a whole exhibit weak optical power and cannot greatly deflect the light. Therefore, by arranging the two cemented lenses of the rear group continuously at the position where the light beam transitions smoothly, the chromatic aberration of different fields of view can be corrected in an approximately consistent manner.
[0063] like Figure 3or Figure 4 As shown, in one embodiment, the rear group 110 further includes a seventh positive power lens 117, and the seventh positive power lens 117 is located between the second cemented lens and the first aberration correction unit.
[0064] In application, by disposing the seventh positive power lens 117 on one side of the two cemented lenses close to the front group 120, the light beam is converged and sent to the front group 120, which can avoid the light beam divergence and increase the aperture aberration. The seventh positive power lens 117 and the first positive power lens 111 and the second positive power lens 112 are distributed on both sides of the two cemented lenses to form an approximately symmetrical "positive-negative-positive" power distribution. This symmetry helps to correct coma and other perpendicular axis aberrations.
[0065] like Figure 5 or Figure 6 As shown, in one embodiment, the rear group 110 further includes a stop 118, and the stop 118 is located between the second cemented lens and the first aberration correction unit.
[0066] In applications, by setting the aperture 118 on the side of the rear group 110 close to the front group 120, the incident angle and light flux of the light beam can be limited, stray light can be eliminated, and off-axis aberrations can be corrected.
[0067] like Figure 7 or Figure 8 As shown, in one embodiment, the rear group 110 further includes a seventh positive power lens 117 and an aperture 118, and the seventh positive power lens 117 and the aperture 118 are sequentially located between the second cemented lens and the first aberration correction unit.
[0068] In application, by sequentially arranging the seventh positive focal power lens 117 and the aperture 118 on the side of the rear group 110 close to the front group 120, it is possible to avoid the beam divergence from increasing the aperture aberration, help correct vertical axis aberrations such as coma, eliminate stray light, and correct off-axis aberrations.
[0069] like Fig. 9 As shown, in one embodiment, the first aberration correction unit includes an eighth positive power lens 121 and a ninth negative power lens 122, and the second aberration correction unit includes a tenth negative power lens 123 and an eleventh positive power lens 124;
[0070] At least one of the ninth negative power lens 122 and the tenth negative power lens 123 has a refractive index lower than or equal to the first refractive index and an Abbe number higher than or equal to the first Abbe number.
[0071] In application, the first aberration correction unit composed of the eighth positive power lens 121 and the ninth negative power lens 122 is used to compensate for aberration. The second aberration correction unit composed of the tenth negative power lens 123 and the eleventh positive power lens 124 is used to correct distortion. The ninth negative power lens 122 and the tenth negative power lens 123 are both made of materials with low refractive index (for example, less than or equal to 1.65) and high Abbe number (for example, greater than or equal to 60) to reduce the generation of chromatic aberration. The optical power distribution of the front group 120 is "positive-negative-negative-positive", and the light beam is lowest at the negative power lens (that is, the ninth negative power lens 122 and the tenth negative power lens 123) and highest at the positive power lens (that is, the eighth positive power lens 121 and the eleventh positive power lens 124), which can correct field curvature, so that clear imaging quality can be obtained on the image side plane.
[0072] In applications, the shapes of the ninth negative power lens and the tenth negative power lens can be set according to actual needs, for example, a biconcave shape or a meniscus shape.
[0073] like Fig. 9 As shown, in one embodiment, the ninth negative power lens 122 is biconcave, and the tenth negative power lens 123 is meniscus.
[0074] like Figure 7 , Figure 8 or Fig. 9 As shown, in one embodiment, all lenses in the projection lens 100 are spherical lenses;
[0075] The rear group 110 includes, in order from the object side to the image side along the optical axis, a first positive power lens 111, a second positive power lens 112, a third negative power lens 113, a fourth positive power lens 114, a fifth positive power lens 115, a sixth negative power lens 116, a seventh positive power lens 117, and a stop 118;
[0076] The front group 120 includes an eighth positive power lens 121 , a ninth negative power lens 122 , a tenth negative power lens 123 , and an eleventh positive power lens 124 .
[0077] like Fig.10 As shown, in one embodiment, the projection lens 100 further includes a display chip 101 , a protection glass 102 , a quarter wave plate 103 , and a polarizer 104 which are located on the object side and arranged in sequence.
[0078] In application, the display chip 101 and the protective glass 102 can be integrated into a whole. The display chip can be selected based on DLP technology, LCOS technology or LCD technology according to actual needs.
[0079] like Fig.11 As shown, in one embodiment, the display chip 101 is implemented based on LCOS technology and has a size of 0.37 inches (i.e., the image plane size), the trapezoidal height of the projection plane of the entire projection lens 100 (i.e., the object plane where the display plane of the display chip 101 is located) is 58 mm, the inclination angle of the projection plane relative to the vertical plane (i.e., the plane perpendicular to the optical axis) is 15°, the aperture F#=2.4, and the type, curvature radius, thickness, and glass material from the object plane to the image plane in the projection lens 100 are shown in Table 1 below:
[0080] Table 1
[0081]
[0082]
[0083]
[0084] like Fig.12 As shown, a schematic diagram of the modulation transfer function (MTF) at the display chip 101 is exemplarily shown; wherein the MTF observation line pair is 90lp / mm, the horizontal axis represents the spatial frequency, the unit is cycles per millimeter (cycles / mm), and the vertical axis represents the value of the MTF.
[0085] In applications, MTF represents the comprehensive analytical ability of the optical system. The MTF value is used to evaluate the imaging quality of the lens. The value range is 0 to 1. The higher and straighter the vertical axis of the MTF curve is, the better the imaging quality of the lens is, the stronger the ability to restore the real image is, the better the overlap of the curves of each field of view is, and the better the consistency of the imaging quality is. Fig.10 It can be seen that in the visible light band, when the spatial frequency is 90lp / mm, the MTF of the entire field of view is ≥0.5, and the imaging quality is good.
[0086] This embodiment further provides a projection device, including the projection lens 100 in any of the above embodiments.
[0087] In application, the projection device may be a HUD device, a projector, etc. By adopting the projection lens provided in the first aspect, a large air back focus, high imaging quality and low cost can be obtained. When the projection device is a HUD device, the display chip 101 in the projection lens 100 can be implemented based on LCOS technology. Since a polarizing beam splitter (PBS) and an aspherical lens are not used, the structure of the projection lens 100 is simplified and the cost of the projection lens 100 is reduced.
[0088] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.
Claims
1. A projection lens, characterized in that: It includes a rear group and a front group arranged in sequence from the object side to the image side along the optical axis; The rear group includes a first positive power lens and a second positive power lens arranged in series and a first cemented lens and a second cemented lens arranged in series; The front group includes a first aberration correction unit and a second aberration correction unit which are arranged in series. The first aberration correction unit and the second aberration correction unit are both composed of a combination of positive and negative optical power lenses. The total optical power of the front group is negative.
2. The projection lens according to claim 1, wherein: The first cemented lens includes a third negative power lens and a fourth positive power lens, and the second cemented lens includes a fifth positive power lens and a sixth negative power lens; The refractive indexes of the fourth positive power lens and the fifth positive power lens are both lower than or equal to the first refractive index, the refractive index of at least one of the third negative power lens and the sixth negative power lens is higher than or equal to the second refractive index, and the first refractive index is lower than the second refractive index; The Abbe numbers of the fourth positive power lens and the fifth positive power lens are both higher than or equal to the first Abbe number, the Abbe number of at least one of the third negative power lens and the sixth negative power lens is lower than or equal to the second Abbe number, and the first Abbe number is higher than the second Abbe number.
3. The projection lens according to claim 1, wherein: The rear group further comprises a seventh positive power lens, and the seventh positive power lens is located between the second cemented lens and the first aberration correction unit; Alternatively, the rear group further includes a stop, and the stop is located between the second cemented lens and the first aberration correction unit; Alternatively, the rear group further includes a seventh positive power lens and an aperture, and the seventh positive power lens and the aperture are sequentially located between the second cemented lens and the first aberration correction unit.
4. The projection lens according to claim 2, wherein: The first aberration correction unit includes an eighth positive power lens and a ninth negative power lens, and the second aberration correction unit includes a tenth negative power lens and an eleventh positive power lens; At least one of the ninth negative power lens and the tenth negative power lens has a refractive index lower than or equal to the first refractive index and an Abbe number higher than or equal to the first Abbe number.
5. The projection lens according to claim 4, wherein: The ninth negative power lens is biconcave, and the tenth negative power lens is meniscus.
6. The projection lens according to claim 2 or 4, characterized in that: The first refractive index is equal to 1.65, and the second refractive index is equal to 1.80; The first Abbe number is equal to 60, and the second Abbe number is equal to 35.
7. The projection lens according to any one of claims 1 to 5, characterized in that: All lenses in the projection lens are spherical lenses.
8. The projection lens according to any one of claims 1 to 5, characterized in that: It also includes a display chip, a quarter wave plate and a polarizing plate which are located on the object side and arranged in sequence.
9. A projection device, characterized in that: The invention comprises the projection lens as claimed in any one of claims 1 to 8.
10. The projection device according to claim 9, characterized in that: The projection device is a head-up display device.