A large-aperture six-piece imaging lens and a high-definition pixel projection imaging device

Abstract

The application discloses a large-aperture six-piece imaging lens and a high-definition pixel projection imaging device, which sequentially comprises, along the direction of the optical axis from the image side to the object side, an aperture stop, a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with negative refractive power, a fifth lens with positive refractive power and a sixth lens with positive refractive power. The image side of the fourth lens and the image side of the sixth lens are both provided with a vignetting stop, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens all adopt glass materials, and the Abbe number Vd of the second lens and the fourth lens is less than or equal to 30. The application realizes effective correction of aberration by optimizing the positive and negative refractive power of each lens, thereby improving the imaging resolving power. In addition, the application adopts a large-aperture design, so that the utilization rate of the light source is obviously improved, and higher brightness can be obtained during projection imaging.

Description

Technical Field

[0001] The present invention relates to the field of optical systems, and in particular to a large-aperture six-piece imaging lens and a high-definition pixel projection imaging device. Background Art

[0002] In recent years, with the rise of connected vehicles, new energy technologies, and autonomous driving, automotive lighting has gradually become intelligent. As the core carrier of vehicle data, headlights not only provide drivers with excellent nighttime visibility but also convey driving information (such as steering and deceleration) to pedestrians and other vehicles. As the demand for intelligent and interactive features in vehicles grows, the methods of information interaction have become diverse. One type of technology achieves visual interaction through integrated LCD panels or LED array display panels placed on the vehicle body, while another type uses projection methods, such as digital light processing (DLP) projection technology based on digital micromirror devices (DMDs), micro laser projection technology based on MEMS, and micro LED projection technology. In comparison, automotive headlight projection lighting technology, which offers greater flexibility in imaging distance and area, shows greater development potential.

[0003] At present, automobile headlight projection lighting technology is divided into: DLP projection technology, micro laser projection technology, liquid crystal projection technology (including projected liquid crystal (LCD) projection and reflective liquid crystal on silicon (LCOS) projection) and pixel-level LED light source projection technology; due to the complex system of micro laser projection technology, the market application is not yet mature, and the poor heat resistance of liquid crystal projection technology, automobile headlight projection technology mainly adopts DLP projection technology and pixel-level LED light source projection technology; among them, although DLP projection technology can achieve higher imaging resolution, the imaging pattern is generated by DMD reflection, and the light source utilization rate is not as good as the simple pixel-level LED light source solution.

[0004] Automotive headlight projection lighting technology utilizes an imaging lens to project a pattern from the object side to the image side. Therefore, the performance of the imaging lens affects both light source utilization and pattern clarity. Therefore, developing an imaging lens that achieves high light source utilization and excellent imaging quality is crucial. Summary of the Invention

[0005] In order to solve the technical problem that the projection lighting technology in the prior art cannot simultaneously ensure high optical utilization and good imaging effects, the present invention provides a large-aperture six-piece imaging lens and a high-definition pixel projection imaging device to solve the above problem.

[0006] The application provides a large-aperture six-piece imaging lens, which comprises, in sequence from the image side to the object side along the optical axis direction, an aperture stop, a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with negative refractive power, a fifth lens with positive refractive power, and a sixth lens with positive refractive power.

[0007] The image side surface and the object side surface of the first lens are S1 surface and S2 surface respectively; the image side surface and the object side surface of the second lens are S3 surface and S4 surface respectively; the image side surface and the object side surface of the third lens are S5 surface and S6 surface respectively; the image side surface and the object side surface of the fourth lens are S7 surface and S8 surface respectively; the image side surface and the object side surface of the fifth lens are S9 surface and S10 surface respectively; and the image side surface and the object side surface of the sixth lens are S11 surface and S12 surface respectively.

[0008] A vignetting diaphragm is arranged on each of the S7 surface and the S11 surface, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are made of glass material, and the Abbe number Vd of the second lens and the fourth lens is less than or equal to 30.

[0009] Further, the S1 surface and the S2 surface are both convex surfaces in the direction from the image side to the object side, the S3 surface is a concave surface, the S4 surface is a convex surface, the S5 surface is a convex surface, the S6 surface is a concave surface, the S7 surface and the S8 surface are both concave surfaces, the S9 surface is a concave surface or a convex surface, the S10 surface is a convex surface, the S11 surface is a convex surface, and the S12 surface is a concave surface.

[0010] Further, the optical back focal length of the imaging lens is greater than 3 mm.

[0011] Further, the aperture coefficient F of the imaging lens is less than 0.74.

[0012] Further, the light source incidence angle θ of the imaging lens is greater than 40°.

[0013] Further, the optical distortion of the imaging lens is less than 3%.

[0014] Further, the effective focal length EFL of the imaging lens satisfies the following condition: 20 mm < EFL < 60 mm.

[0015] Further, the total track length TTL of the imaging lens satisfies the following condition: 45 mm < TTL < 135 mm.

[0016] Further, the half field of view HFOV of the imaging lens satisfies the following condition: 6° < HFOV < 15°.

[0017] Further, the contrast of the imaging lens is greater than 0.6 at a characteristic frequency of 6.25 lp / mm.

[0018] Further, the refractive index Nd of at least two of the first lens, the third lens, the fourth lens and the fifth lens is greater than or equal to 1.8.

[0019] The application further provides a high-definition pixel projection imaging device, comprising an LED light source and the large-aperture six-lens imaging lens described above; wherein the LED light source is located on the object side of the S12 plane.

[0020] Further, the number of pixels of the LED light source is greater than 10,000, and the LED light source is a Micro LED or a Mini LED.

[0021] The application has the following beneficial effects:

[0022] The large-aperture six-lens imaging lens and the high-definition pixel projection imaging device of the application can effectively correct aberration by optimizing the positive and negative focal lengths of the lenses, thereby improving the imaging resolution; the large-aperture design of the application can significantly improve the light source utilization rate, and higher brightness can be obtained in projection imaging; meanwhile, the lenses in the application are made of glass material, and the projection effect can still be clear under the condition of-40℃ to 80℃, and the application in vehicle lamps has better stability; in addition, the application comprises six spherical lenses, has low manufacturing cost, simple and stable overall structure, good single part and assembly tolerance, and good manufacturability. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will be further described below in combination with the drawings and examples.

[0024] Figure 1 FIG. 1 is a schematic diagram of the overall structure of the imaging lens of the application example one;

[0025] Figure 2 FIG. 2 is a schematic diagram of the overall structure of the high-definition pixel projection imaging device of the application example one;

[0026] Figure 3 FIG. 3 is a field distortion diagram of the imaging lens of the application example one;

[0027] Figure 4 FIG. 4 is an MTF diagram of the imaging lens of the application example one;

[0028] Figure 5 FIG. 5 is a Through-Focus-MTF diagram of the imaging lens of the application example one with a frequency of 6.25lp / mm;

[0029] Figure 6 FIG. 6 is a schematic diagram of the overall structure of the imaging lens of the application example two;

[0030] Figure 7A field-distortion diagram of the imaging lens of Embodiment Two of the present application;

[0031] Figure 8 An MTF diagram of the imaging lens of Embodiment Two of the present application;

[0032] Figure 9 A schematic diagram of the overall structure of the imaging lens of Embodiment Three of the present application;

[0033] Figure 10 A field-distortion diagram of the imaging lens of Embodiment Three of the present application;

[0034] Figure 11 An MTF diagram of the imaging lens of Embodiment Three of the present application.

[0035] In the figure, 1 is a first lens, 2 is a second lens, 3 is a third lens, 4 is a fourth lens, 5 is a fifth lens, 6 is a sixth lens, 7 is an optical axis, 8 is an LED light source, and 9 is an aperture stop. DETAILED DESCRIPTION

[0036] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0037] As shown in Figure 1 the present application provides a large-aperture six-piece imaging lens, which includes, in order from the image side to the object side along the direction of the optical axis 7: an aperture stop 9, a first lens 1 having positive refractive power, a second lens 2 having negative refractive power, a third lens 3 having positive refractive power, a fourth lens 4 having negative refractive power, a fifth lens 5 having positive refractive power, and a sixth lens 6 having positive refractive power.

[0038] Among them, the image side and object side of the first lens 1 are S1 and S2 respectively; the image side and object side of the second lens 2 are S3 and S4 respectively; the image side and object side of the third lens 3 are S5 and S6 respectively; the image side and object side of the fourth lens 4 are S7 and S8 respectively; the image side and object side of the fifth lens 5 are S9 and S10 respectively; and the image side and object side of the sixth lens 6 are S11 and S12 respectively.

[0039] Surfaces S7 and S11 are both provided with vignetting stops. To ensure the stability of the imaging lens, the first lens element 1, the second lens element 2, the third lens element 3, the fourth lens element 4, the fifth lens element 5, and the sixth lens element 6 are all made of glass. This is because glass has a low thermal expansion coefficient in an operating environment of -40°C to 80°C. This ensures that the imaging lens of the present invention can produce clear projection effects when used for long-term vehicle light projection.

[0040] The present invention includes a total of six spherical lenses, which are easy to process and assemble. By reasonably matching positive and negative optical power lenses, the present invention can effectively eliminate aberrations under large aperture conditions, while improving the utilization rate of the light source and taking into account the clarity of the projection imaging, and perfectly restore the desired projection pattern.

[0041] The aperture stop 9 in the present invention is located on the image side of the first lens 1 or on the S1 surface (in this case, the S1 surface of the first lens 1 is the aperture stop 9). At the same time, in order to better correct lens chromatic aberration, the second lens 2 and the fourth lens 4 are made of high-dispersion glass material, that is, the Abbe number Vd ≤ 30.

[0042] According to one embodiment of the present invention, along the direction from the image side to the object side, the S1 surface and the S2 surface are both convex surfaces, the S3 surface is a concave surface, the S4 surface is a convex surface, the S5 surface is a convex surface, the S6 surface is a concave surface, the S7 surface and the S8 surface are both concave surfaces, the S9 surface is a concave surface or a convex surface, the S10 surface is a convex surface, the S11 surface is a convex surface, and the S12 surface is a concave surface.

[0043] In the present invention, the optical back focus of the imaging lens is greater than 3 mm, that is, the minimum distance between the S12 surface and the LED light source 8 is greater than 3 mm. Since the LED light source 8 needs to be placed for projection pattern input, space is left between the imaging lens and the LED light source 8 to ensure the safety and convenience of assembling the projection imaging device.

[0044] In order to obtain better luminous flux, the aperture coefficient F of the imaging lens of the present invention needs to be less than 0.74.

[0045] The light source incident angle θ of the imaging lens of the present invention is greater than 40°, where θ is the half-field angle of the maximum incident angle of the object plane light beam that can enter the lens. Since the light beam emitted by the LED light source 8 is evenly diffused in all directions when the imaging lens is used for automobile headlight projection imaging, the larger the light source incident angle of the lens, the more light beams enter the lens, and the higher the light source utilization rate of the final imaging will be.

[0046] The optical distortion of the imaging lens of the present invention is less than 3%. Since the lens of the present invention is used in projection technology, excessive distortion will cause distortion of the projected pattern and make the projected pattern difficult to correct. Therefore, the imaging lens has the characteristic of small distortion to ensure lossless restoration of the pattern.

[0047] The effective focal length EFL of the imaging lens satisfies the following condition: 20mm < EFL < 60mm.

[0048] The total optical length TTL of the imaging lens satisfies the following condition: 45mm < TTL < 135mm. TTL represents the longest horizontal distance from the S1 plane to the object plane.

[0049] The half field of view HFOV of the imaging lens satisfies the following condition: 6° < HFOV < 15°. The field of view and the focal length satisfy the following relationship: IH = EFL*tan(HFOV), where IH represents the pattern height during projection; therefore, in the case of a constant pattern, the greater the EFL, the smaller the HFOV, and the farther the projection distance, and vice versa.

[0050] The imaging resolution of the imaging lens satisfies the following condition: MTF > 60% @ 6.25LP / MM; where MTF is the modulation transfer function, which reflects the contrast and resolution of the imaging lens; MTF > 60% @ 6.25lp / mm means that at a feature frequency of 6.25lp / mm, the contrast of the imaging lens is greater than 0.6.

[0051] The refractive index Nd of at least two lenses among the first lens 1, the third lens 3, the fourth lens 4, and the fifth lens 5 of the imaging lens is greater than or equal to 1.8.

[0052] A high-definition pixel projection imaging device, as shown in Figure 2 The LED light source 8 is placed on the object side of the S12 plane in the imaging lens, and in order to obtain the projection effect of high-definition pixels, the number of pixels of the LED light source 8 is greater than 10,000, and the LED light source 8 adopts Micro LED or Mini LED.

[0053] In summary, the large-aperture six-piece imaging lens and the high-definition pixel projection imaging device according to the above limitations are set up, the optical power and material of the six lenses are reasonably matched, so that the aberration of the lens is well corrected under the condition of large aperture; at the same time, the lenses in the lens all adopt spherical glass properties, the lens manufacturing process is mature, has good manufacturability, and the glass has good heat resistance, so that the lens can reduce the virtual focus phenomenon caused by temperature drift in car lamp projection.

[0054] The following three specific embodiments are given according to the above settings of the present application, to specifically illustrate the imaging lens and the high-definition pixel projection imaging device of the present application. The lens of the present application has six lenses, and the aperture stop 9 is located on the S1 plane or the image side direction of the S1 plane.

[0055] The three groups of example data are as follows in Table 1:

[0056] Conditional Example 1 Example 2 Example 3 20 mm < EFL < 60 mm 30.89 mm 23.25 mm 60 mm 45 mm < TTL < 135 mm 60 mm 45 mm 135 mm 6° < HFOV < 15° 12° 15° 6° MTF > 60% @ 6.25 lp / mm MTF > 70% @ 6.25 lp / mm MTF > 60% @ 6.25 lp / mm MTF > 90% @ 6.25 lp / mm

[0057] Table 1

[0058] Example One

[0059] Figure 1 The overall structure schematic diagram of the imaging lens of Example One of the present application is shown in the figure.

[0060] In this embodiment, the total length of the lens TTL = 60mm, the F number = 0.73, the focal length EFL = 30.89mm, the half field of view HFOV = 12°, the optical back focus is greater than 3mm, and the lens resolution MTF > 70% @ 6.25LP / MM; the aperture stop 9 is located on the image side of the first lens 1, wherein the six lenses are all made of glass material, the second lens 2 and the fourth lens 4 are made of high dispersion (Abbe number Vd≤30) material for correcting chromatic aberration, and the refractive index Nd≥1.8 of the first lens 1, the third lens 3, the fourth lens 4 and the fifth lens 5.

[0061] The relevant parameters of each lens of this embodiment are listed in Table 2 below:

[0062]

[0063] Table 2

[0064] Figure 2 The overall structure schematic diagram of the high-definition pixel projection imaging device of the present application is shown in the figure, Figures 3-5 The field distortion diagram, the MTF diagram and the Through-Focus-MTF diagram with a frequency of 6.25lp / mm of the imaging lens of Example One of the present application are shown in the figures. It can be known from the figures that the imaging lens obtained according to Example One of the present application can be used for high-definition pixel projection, and in the case of a large aperture, the lens has good image resolution, and the glass has good heat resistance, so that the lens can reduce the phenomenon of virtual focus caused by temperature drift in vehicle lamp projection.

[0065] Example Two

[0066] Figure 6 The overall structure schematic diagram of the imaging lens of Example Two of the present application is shown in the figure.

[0067] In the embodiment, the total length of the optical lens TTL = 45mm, the F number = 0.73, the focal length EFL = 23.25mm, the half field of view HFOV = 15°, the optical back focus is greater than 3mm, and the lens resolution MTF > 60% @ 6.25lp / mm; the aperture stop 9 is located on the S1 surface, wherein the six lenses are made of glass material, the second lens 2 and the fourth lens 4 are made of high dispersion (Abbe number Vd ≤ 30) material for correcting chromatic aberration, and the refractive index Nd of the first lens 1, the third lens 3 and the fifth lens 5 is greater than 1.8.

[0068] The following table 3 lists the related parameters of each lens in the embodiment

[0069] Surface Number Surface Type Curvature Radius R Thickness Refractive Index Abbe Number Aperture D Stop Sphere Infinity -1.6248 15.944 S1 Sphere 79.0404 6.9055 1.849 35.8 15.944 S2 Sphere -58.3009 2.9225 15.766 S3 Sphere -33.0842 2.0 1.885 19.0 15.223 S4 Sphere -89.6235 0.1000 15.533 S5 Sphere 19.0556 9.5827 1.835 42.7 15.327 S6 Sphere 2136.2712 2.1965 14.312 S7 Sphere -88.4383 2 1.738 23.7 12.140 S8 Sphere 12.6189 3.9086 9.622 S9 Sphere 60.6354 3.6424 1.835 42.7 9.678 S10 Sphere -41.7147 0.1 9.763 S11 Sphere 17.7460 7.6640 1.846 36.9 9.362 S12 Object 39.4027 3.9778 7.790 Sphere Infinity Figures 7-8

[0070] Table 3

[0071] Figure 9 The field distortion diagram and the MTF diagram of the imaging lens of the second embodiment of the application are respectively shown. It can be known from the drawings that the imaging lens obtained according to the second embodiment of the application can be used for high-definition pixel projection, and in the case of a large aperture, the lens has good image resolution, and the glass has good heat resistance, so that the lens can reduce the phenomenon of virtual focus caused by temperature drift in vehicle lamp projection.

[0072] Embodiment three:

[0073] Figures 10-11 The embodiment three is a schematic diagram of the whole structure of the imaging lens.

[0074] In the embodiment, the total length of the optical lens TTL = 135mm, the F number = 0.73, the effective focal length EFL = 60mm, the half field of view HFOV = 6°, the optical back focus is greater than 3mm, and the lens resolution MTF > 90% @ 6.25lp / mm; the aperture stop 9 is located on the S1 surface, wherein the six lenses are made of glass material, the second lens 2 and the fourth lens 4 are made of high dispersion (Abbe number Vd ≤ 30) material for correcting chromatic aberration, and the refractive index Nd of the first lens 1, the third lens 3, the fourth lens 4 and the fifth lens 5 is greater than 1.8.

[0075] The following table 4 lists the related parameters of each lens in the embodiment

[0076]

[0077]

[0078] Table 4

[0079] ​The field distortion diagram and the MTF diagram of the imaging lens according to the third embodiment of the present application are shown respectively. It can be known in combination with the drawings that the imaging lens obtained according to the third embodiment of the present application can be used for high-definition pixel projection, and in the case of a large aperture, the lens has good image resolution, and the glass has good heat resistance, so that the lens can reduce the phenomenon of virtual focus caused by temperature drift in vehicle lamp projection.

[0080] In this specification, illustrative statements about the term do not necessarily refer to the same embodiment. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments in a suitable manner.

[0081] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A large-aperture six-element imaging lens, characterized in that: Along the optical axis (7) from the image side to the object side, it includes: Aperture stop (9); A first lens (1) having positive optical power, wherein the image side surface and the object side surface of the first lens (1) are respectively an S1 surface and an S2 surface; A second lens (2) having negative optical power; the image side surface and the object side surface of the second lens (2) are respectively an S3 surface and an S4 surface; a third lens (3) having positive optical power; the image side surface and the object side surface of the third lens (3) are respectively an S5 surface and an S6 surface; a fourth lens (4) having negative optical power; the image side surface and the object side surface of the fourth lens (4) are respectively an S7 surface and an S8 surface; a fifth lens (5) having positive optical power; the image side surface and the object side surface of the fifth lens (5) are respectively an S9 surface and an S10 surface; a sixth lens (6) having positive optical power; the image side surface and the object side surface of the sixth lens (6) are respectively an S11 surface and an S12 surface; Wherein, vignetting stops are provided at the S7 surface and the S11 surface, the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) are all made of glass materials, and the Abbe number Vd of the second lens (2) and the fourth lens (4) is ≤30; Along the image side to the object side, the S1 surface and the S2 surface are both convex surfaces, the S3 surface is a concave surface, the S4 surface is a convex surface, the S5 surface is a convex surface, the S6 surface is a concave surface, the S7 surface and the S8 surface are both concave surfaces, the S9 surface is a concave surface or a convex surface, the S10 surface is a convex surface, the S11 surface is a convex surface, and the S12 surface is a concave surface; The light source incident angle θ of the imaging lens is greater than 40°; the effective focal length EFL of the imaging lens satisfies the following conditions: 20mm<EFL<60mm; the total lens length TTL of the imaging lens satisfies the following conditions: 45mm<TTL<135mm; the half field of view HFOV of the imaging lens satisfies the following conditions: 6°<HFOV<15°.

2. The large-aperture six-element imaging lens according to claim 1, wherein: The optical back focus of the imaging lens is greater than 3 mm.

3. The large-aperture six-element imaging lens according to claim 1, wherein: The aperture coefficient of the imaging lens is F<0.

74.

4. The large-aperture six-element imaging lens according to claim 1, wherein: The optical distortion of the imaging lens is less than 3%.

5. The large-aperture six-element imaging lens according to any one of claims 1 to 4, characterized in that: At a characteristic frequency of 6.25 lp / mm, the contrast of the imaging lens is greater than 0.

6.

6. The large-aperture six-element imaging lens according to any one of claims 1 to 4, characterized in that: The refractive index Nd of at least two lenses among the first lens (1), the third lens (3), the fourth lens (4), and the fifth lens (5) is ≥1.

8.

7. A high-definition pixel projection imaging device, characterized by: The invention comprises an LED light source (8) and a large-aperture six-piece imaging lens according to any one of claims 1 to 6; wherein the LED light source (8) is located on the object side of the S12 surface.

8. The high-definition pixel projection imaging device according to claim 7, characterized in that: The number of pixels of the LED light source (8) is greater than 10,000, and the LED light source (8) is a Micro LED or a Mini LED.

Images