Projection optical system and projection module applied by same

Abstract

The invention provides a projection optical system and a projection module applying the same, the projection optical system is composed of six lenses, the first lens has negative focal power, and the imaging side surface of the first lens is a concave surface; the second lens has focal power; the third lens has positive focal power, and the image source side surface of the third lens is a convex surface; the fourth lens has focal power, and the imaging side surface of the fourth lens is a convex surface; the fifth lens has positive focal power, and the image source side surface of the fifth lens is a convex surface; the sixth lens has negative focal power, the imaging side surface of the sixth lens is a concave surface, and the image source side surface of the sixth lens is a convex surface; by reasonably configuring the refractive power and the surface type of each lens, the field curvature, distortion and chromatic aberration of magnification are effectively corrected, a high-quality picture with bright edge and uniform resolution is obtained, and the projection optical system has the characteristics of small overall size, low cost and large aperture, is compact in structure and convenient to process and install, and meanwhile, has a wide application prospect. The configuration of the large aperture can increase the light incoming amount of the optical system and improve the imaging quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging, in particular to a projection optical system and a projection module using the same. BACKGROUND

[0002] In recent years, projection and augmented reality (AR) systems have higher requirements for miniaturization, high definition and low chromatic aberration of optical modules. Traditional systems often use more lenses to correct image quality, resulting in complex structure and large volume. At the same time, how to realize image plane and flat field output in limited space is still a technical difficulty, and the existing design often cannot balance brightness, contrast and optical total length, limiting its application in lightweight AR devices and miniature projectors.

[0003] Therefore, there is an urgent need for an optical system architecture with compact structure, good aberration control and high optical performance. SUMMARY

[0004] The present application provides a projection optical system, which effectively corrects field curvature, distortion and magnification chromatic aberration by reasonably configuring the refractive power and surface shape of each lens, and obtains a high-quality image with bright edges and uniform resolution.

[0005] A projection optical system, characterized in that: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens are sequentially arranged along the optical axis from the imaging side to the image source side; The first lens has a negative focal power, and its imaging side surface is concave; The second lens has a focal power; The third lens has a positive focal power, and its image source side surface is convex; The fourth lens has a focal power, and its imaging side surface is convex; The fifth lens has a positive focal power, and its image source side surface is convex; The sixth lens has a negative focal power, and its imaging side surface is concave, and its image source side surface is convex.

[0006] Preferably, the optical system satisfies the following conditions: 1.4 mm<(FNO*f*ImgH) / TTL<1.7 mm; Wherein, FNO is the F number of the optical system, f is the effective focal length of the optical system, ImgH is half of the diagonal length of the effective pixel area on the image source surface of the optical system, and TTL is the axial distance from the imaging side surface of the first lens of the optical system to the image source surface of the optical system.

[0007] Preferably, the optical system satisfies the following relationship: 3.0 / mm< TTL / (EPD*T01) < 4.0 / mm; Wherein, TTL is the axial distance from the first lens imaging side surface of the optical system to the image source surface of the optical system, EPD is the entrance pupil diameter of the optical system, T01 is the axial distance from the imaging surface of the optical system to the imaging side surface of the first lens.

[0008] Preferably, the optical system satisfies the following relationship: 0.29 < DT62 / |R12| < 1. Wherein, R12 is the radius of curvature of the image source side surface of the sixth lens, DT62 is the maximum effective radius of the image source side surface of the sixth lens.

[0009] Preferably, the optical system satisfies the following relationship: 14.0 < f*tan(HFOV) / |SAG1| < 20.0; wherein, f is the effective focal length of the optical system, HFOV is half of the maximum field of view angle of the optical system, SAG1 is the distance from the maximum effective clear aperture of the imaging side surface of the first lens to the intersection of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis.

[0010] Preferably, the optical system satisfies the following relationship: 1.0 < (CT1+CT6) / |SAG1 +SAG12| < 2.0; wherein, CT1 is the thickness of the first lens on the optical axis, CT6 is the thickness of the sixth lens on the optical axis, SAG1 is the distance from the maximum effective clear aperture of the imaging side surface of the first lens to the intersection of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis, SAG12 is the distance from the maximum effective clear aperture of the image source side surface of the sixth lens to the intersection of the image source side surface of the sixth lens and the optical axis in the direction parallel to the optical axis.

[0011] Preferably, the optical system satisfies the following relationship: 3.3 < ΣCT / CT3< 6.0; wherein, ΣCT is the sum of the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens on the optical axis of the optical system, CT3 is the central thickness of the third lens on the optical axis.

[0012] Preferably, the optical system satisfies the following relationship: 15.5 < BFL / (T12+ T23) < 18.5; Wherein, BFL is the shortest distance from the image source side surface of the sixth lens to the image source surface of the optical system in the direction of the optical axis, T12 is the air gap of the first lens and the second lens on the optical axis, T23 is the air gap of the second lens and the third lens on the optical axis.

[0013] Preferably, the optical system satisfies the following relationship: 1.0 < |(f3-f1) / f3| < 3.0; wherein, f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens.

[0014] Preferably, the optical system satisfies the following relationship: 1.6 < f / f345 < 1.9; wherein, f is the effective focal length of the optical system, and f345 is the effective focal length of the third lens, the fourth lens and the fifth lens.

[0015] Preferably, the optical system satisfies the following relationship: 2.2 < | (f23+f456) / f | < 5.0; wherein, f is the effective focal length of the optical system, f23 is the combined focal length of the second lens and the third lens, and f456 is the combined focal length of the fourth lens, the fifth lens and the sixth lens.

[0016] Preferably, the F number of the optical system is ≤1.89, and the total optical length TTL satisfies: TTL ≤12 mm.

[0017] Another object of the present application is to provide a projection module comprising at least an optical lens, wherein the optical lens is installed with the above-mentioned projection optical system.

[0018] Compared with the prior art, the present application has the following advantages: The present application provides a projection optical system and a projection module using the same, which is composed of six lenses. By reasonably configuring the refractive power and surface shape of each lens, the field curvature, distortion and magnification chromatic aberration are effectively corrected, and a high-quality image with bright edges and uniform resolution is obtained. The projection optical system of the present application has the characteristics of small overall size, low cost and large aperture, and is compact in structure, easy to process and install. Meanwhile, the configuration of large aperture can increase the light quantity of the optical system and improve the imaging quality. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows.

[0020] Figure 1 is a structural schematic diagram of the optical system or the projection module of the embodiment 1 of the present application; Figure 2 is the on-axis chromatic aberration, astigmatism and distortion curve of the optical system or the projection module of the embodiment 1 of the present application; Figure 3 is a structural schematic diagram of the optical system or the projection module of the embodiment 2 of the present application; Figure 4 is the on-axis chromatic aberration, astigmatism and distortion curve of the optical system or the projection module of the embodiment 2 of the present application; Figure 5 is a structural schematic diagram of the optical system or the projection module of the embodiment 3 of the present application; Figure 6is the on-axis chromatic aberration, astigmatism and distortion curve of the optical system or projection module of Embodiment 3 of the present application; Figure 7 is a structural schematic diagram of the optical system or projection module of Embodiment 4 of the present application; Figure 8 is the on-axis chromatic aberration, astigmatism and distortion curve of the optical system or projection module of Embodiment 4 of the present application. DETAILED DESCRIPTION

[0021] The present application provides a projection optical system, sequentially arranged along an optical axis from an imaging side to an image source side are a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5 and a sixth lens E6, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5 and the sixth lens E6 are aspherical lenses, and are all arranged with air as a separation interval; the first lens E1 has a negative focal power, and its imaging side surface is concave; the second lens E2 has a focal power; the third lens E3 has a positive focal power, and its image source side surface is convex; the fourth lens E4 has a focal power, and its imaging side surface is convex; the fifth lens E5 has a positive focal power, and its image source side surface is convex; the sixth lens E6 has a negative focal power, and its imaging side surface is concave, and its image source side surface is convex; the F number of the imaging optical system is ≤1.89, and the overall length is ≤12 mm.

[0022] The optical system of the embodiment of the present application is composed of six lenses, by reasonably configuring the refractive power and surface type of each lens, the field curvature, distortion and magnification chromatic aberration are effectively corrected, a high-quality picture with bright edges and uniform resolution is obtained, the projection optical system configured by the present application has the characteristics of small overall size, low cost and large aperture, the structure is compact, convenient for processing and installation, at the same time, the configuration of the large aperture can increase the light amount of the optical system and the imaging quality is higher.

[0023] Further, the optical system satisfies the following relationship: 1.4 mm < (FNO*f*ImgH) / TTL < 1.7 mm; wherein FNO is the F number of the optical projection lens, f is the effective focal length of the optical system, ImgH is half of the diagonal length of the effective pixel area on the image source plane of the optical lens, and TTL is the axial distance from the imaging side surface of the first lens to the image source plane of the optical lens. By limiting the ratio of the aperture, the effective focal length, and half of the diagonal length of the effective pixel area on the image source plane to the axial distance from the imaging side surface of the first lens to the image source plane of the optical projection system, the aberration can be ensured to be within a correctable range, and the design complexity is reduced. When the lower limit of the relationship is exceeded, the total length of the optical system is further increased on the basis of ensuring a large aperture of the optical system, which is not conducive to the miniaturization of the optical system; when the upper limit of the relationship is exceeded, it is not conducive to satisfying the field of view angle range of the optical lens, and sufficient image space information cannot be transmitted, which affects the projection quality of the optical lens.

[0024] Further, the optical system satisfies the following relationship: 3.0 / mm < TTL / (EPD*T01) < 4.0 / mm; wherein TTL is the axial distance from the imaging side surface of the first lens to the image source plane of the optical lens, EPD is the entrance pupil diameter of the optical system, and T01 is the axial distance from the imaging plane of the optical system to the imaging side surface of the first lens. By limiting the ratio range of the axial distance from the imaging side surface of the first lens to the image source plane of the optical lens to the entrance pupil diameter of the optical system and the axial distance from the imaging plane of the optical system to the imaging side surface of the first lens, the system can be ensured to have high brightness and sufficient distance to accommodate structural elements while minimizing the total length of the optical system, thereby achieving the unification of high performance and small size. When the lower limit of the relationship is exceeded, the distance from the imaging plane of the optical system to the imaging side surface of the first lens is too small, which is not conducive to the layout of structural elements such as a lens barrel, thereby affecting the engineering practicability of the entire optical lens; when the upper limit of the relationship is exceeded, the system structure is long, and it is difficult to achieve the unification of high performance and miniaturization.

[0025] Further, the optical system satisfies the following relationship: 0.29 < DT62 / |R12| < 1; wherein R12 is the curvature radius of the sixth lens image source side surface, and DT62 is the maximum effective radius of the sixth lens image source side surface. By limiting the ratio of the maximum effective radius of the sixth lens image source side surface to the curvature radius of the image source side surface, the bending degree of the image source side surface of the sixth lens is reasonably controlled, and the aperture of the sixth lens in the direction perpendicular to the optical axis is increased, thereby improving the relative illumination of the projection; at the same time, it is also beneficial to suppress the aberration of the edge field of view and improve the projection quality of the system. When lower than the lower limit of the relationship, the effective aperture of the image source side surface of the sixth lens is too small, resulting in serious deflection of the edge light and increased edge aberration, which is not conducive to the improvement of the projection quality. When higher than the upper limit of the relationship, the image side surface of the sixth lens is too curved, and the deflection degree of the light is too large, which also easily leads to the increase of the edge aberration, which is not conducive to the improvement of the projection quality.

[0026] Further, the optical system satisfies the following relationship: 14.0 < f*tan(HFOV) / |SAG1| < 20.0; wherein f is the effective focal length of the optical system, HFOV is half of the maximum field of view angle of the optical system, and SAG1 is the distance from the maximum effective clear aperture of the first lens imaging side surface to the intersection of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis. By controlling the ratio range of the above relationship, the ratio of the focal length of the optical system, half of the maximum field of view angle of the optical system, and the distance from the maximum effective clear aperture of the first lens imaging side surface to the intersection of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis is controlled, which can effectively control the field of view angle of the optical system, so that the light passes through the optical system to the imaging surface reasonably, thereby improving the projection quality of the system. Lower than the lower limit of the relationship, the maximum field of view angle of the optical system is too small, and the imaging surface cannot obtain sufficient image space information; higher than the upper limit of the relationship, the distance from the maximum effective clear aperture of the first lens imaging side surface to the intersection of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis is too small, the imaging side surface of the first lens is too flat, resulting in too large deflection angle when the edge light enters, the edge aberration increases, and the projection quality of the system is affected Further, the optical system satisfies the following relationship: 3.3 < ΣCT / CT3 < 6.0; wherein, ΣCT is the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis. By limiting the range of the above condition formula, the ratio of the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens on the optical axis to the center thickness of the third lens can be reasonably configured, which is conducive to the reasonable deflection of light when passing through the third lens, thereby improving the projection quality of the system, and also conducive to controlling the center thickness of the third lens on the optical axis, so that the third lens is easy to process and produce. Below the lower limit of the relationship, the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens on the optical axis is too small, and the thickness ratio of each lens in the optical system changes too much, which is not conducive to the reasonable deflection of light, reduces the MTF value of the system, and leads to the decline of the resolution of the system; above the upper limit of the relationship, the center thickness of the third lens on the optical axis is too small, which makes the processability of the third lens too low, and is not suitable for the practicality of the optical system.

[0027] Further, the optical system satisfies the following relationship: 1.0 < |(f3-f1) / f3| < 3.0; wherein, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens. By reasonably controlling the focal length ratio of the first lens and the third lens, the optical system can meet the large field of view angle range while also obtaining high projection resolution. Exceeding the upper limit of the relationship, the refractive power of the first lens and the third lens is insufficient, so that the light from the image source surface is difficult to refract into the imaging surface, which is not conducive to expanding the field of view angle range of the optical system; below the lower limit of the relationship, the refractive power of the first lens and the third lens is too strong, which is easy to produce strong astigmatism and chromatic aberration, which is not conducive to high resolution projection characteristics.

[0028] Further, the optical system satisfies the following relationship: 1.6 < f / f345 < 1.9; wherein, f is the effective focal length of the optical projection system, and f345 is the effective combined focal length of the third lens, the fourth lens and the fifth lens. By constraining the ratio of the combined focal length of the third lens, the fourth lens and the fifth lens to the effective focal length of the optical lens, the refractive power of the third lens, the fourth lens and the fifth lens can be properly distributed, so that the fourth lens can produce various matching properties, thereby achieving the balance of internal aberration of the optical lens on the basis of meeting the miniaturization design of the optical lens, and further helping to adjust the field curvature and astigmatism of the projection edge of the optical lens, and meeting the projection quality of the optical lens to the surrounding environment.

[0029] Further, the optical system satisfies the following relationship: 2.2<|(f23+f456) / f|<5.0; wherein f23 is a combined focal length of the second lens and the third lens, f456 is a combined focal length of the fourth lens, the fifth lens and the sixth lens, and f is an effective focal length of the optical projection system. By making the optical system satisfy the above relationship, the ratio of the combined focal length of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens to the focal length of the optical system is reasonably constrained, the aberration generated by the lens after the light passes through the sixth lens is corrected, the resolving power of the optical system is improved, and meanwhile, the exiting angle of the light after being folded by the optical system is reduced, so that the light emitted by the image source can enter the optical system at a smaller angle, thereby improving the optical performance of the image surface and the projection quality of the projection module.

[0030] Further, the optical system satisfies the following relationship: 1.0<(CT1+CT6) / |SAG1 +SAG12|<2.0; wherein CT1 is the thickness of the first lens on the optical axis, CT6 is the thickness of the sixth lens on the optical axis, SAG1 is the distance from the maximum effective clear aperture of the imaging side of the first lens to the intersection of the imaging side of the first lens and the optical axis in the direction parallel to the optical axis, and SAG12 is the distance from the maximum effective clear aperture of the image source side of the sixth lens to the intersection of the image source side of the sixth lens and the optical axis in the direction parallel to the optical axis. By the ratio range of the above expression, the shape of the first lens and the sixth lens can be constrained to correct the field curvature of the projection optical lens and reduce the risk of ghost image generation, thereby improving the projection quality of the optical lens. When the ratio is lower than the upper limit, the sag of the imaging side of the first lens and the image source side of the sixth lens is too large, the imaging side of the first lens and the image source side of the sixth lens are too curved, which is not conducive to the manufacturing and assembly of the first lens and the sixth lens, and is easy to cause the projection quality of the optical lens to decrease; higher than the upper limit of the relationship, the thickness of the first lens and the sixth lens on the optical axis is too large, which is not conducive to the miniaturization design of the optical system Further, the optical system satisfies the following relationship: 15.5 < BFL / (T12+T23) < 18.5; wherein, BFL is the shortest distance from the image source side surface of the sixth lens to the image source surface of the optical system in the direction of the optical axis, T12 is the air gap of the first lens and the second lens in the direction of the optical axis, and T23 is the air gap of the second lens and the third lens in the direction of the optical axis. When the above condition is satisfied, by controlling the shortest distance from the image source side surface of the sixth lens to the image source surface of the optical system in the direction of the optical axis within a reasonable range, the matching degree between the image source and the prism and the optical system is effectively ensured, the matching of the optical system and the image source screen is ensured, the thickness of the above combined lens in the direction of the optical axis is controlled, the compactness of the combined lens structure is effectively improved, the total length of the optical system is reduced, the size of the optical system is further reduced, the development in the direction of miniaturization is better, and the combined lens forming and assembling are facilitated, the manufacturing cost of the optical system is reduced, and the eccentricity sensitivity of the optical system is reduced, which is beneficial to ensuring the projection effect of the optical system. Embodiment one, The optical projection lens according to Embodiment 1 of the present application is described below. Figures 1 to 2 The structure of the optical projection lens according to Embodiment 1 of the present application is shown in the figure. Figure 1 The structure of the optical projection lens according to Embodiment 1 of the present application is shown in the figure.

[0031] As Figure 1 shown, the optical projection lens according to the exemplary embodiment of the present application sequentially includes, along the optical axis from the imaging side to the image source side, an imaging surface STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and an image source surface S15.

[0032] The first lens E1 has a negative focal power, the imaging side surface S1 is concave, and the image source side surface S2 is concave. The second lens E2 has a positive focal power, the imaging side surface S3 is convex, and the image source side surface S4 is concave. The third lens E3 has a positive focal power, the imaging side surface S5 is convex, and the image source side surface S6 is convex. The fourth lens E4 has a positive focal power, the imaging side surface S7 is convex, and the image source side surface S8 is concave. The fifth lens E5 has a positive focal power, the imaging side surface S9 is convex, and the image source side surface S10 is convex. The sixth lens E6 has a negative focal power, the imaging side surface S11 is concave, and the image source side surface S12 is convex. The image side surface S14. The light from the image source surface S15 sequentially passes through each surface S14 to S1 and finally forms an image on the imaging surface STO.

[0033] Table 1 shows the surface type, curvature radius, thickness, and material of each lens of the optical projection lens of Embodiment 1, wherein the units of the curvature radius and the thickness are millimeters (mm).

[0034] Table 1

[0035] [5] In Table 1, the imaging side and image source side of any one of the lenses, namely the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5 and the sixth lens E6, are Q-type aspherical surfaces. The surface shape of each aspherical lens can be limited by, but is not limited to, the following aspherical formula:

[0036] Where Z is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex of the surface, r is the radial coordinate of the aspherical surface, c is the curvature of the vertex of the aspherical surface, K is the conic coefficient, Am is the aspherical coefficient, and r max The maximum value of the radial radius coordinate is u = r / r max Table 4 provides the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 for each aspherical surface that can be used in the first embodiment.

[0037] Table 2

[0038] Example 2 The following is for reference Figures 3 to 4 Describes an optical projection lens according to Embodiment 2 of this application. Figure 3 A schematic diagram of the structure of an optical projection lens according to Embodiment 2 of this application is shown.

[0039] like Figure 3 As shown, the optical projection lens according to an exemplary embodiment of this application includes, in sequence along the optical axis from the imaging side to the image source side: imaging surface STO, first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, sixth lens E6 and image source surface S15.

[0040] The first lens E1 has negative optical power, with its imaging side S1 being concave and its image source side S2 being convex. The second lens E2 has negative optical power, with its imaging side S3 being concave and its image source side S4 being concave. The third lens E3 has positive optical power, with its imaging side S5 being concave and its image source side S6 being convex. The fourth lens E4 has positive optical power, with its imaging side S7 being convex and its image source side S8 being convex. The fifth lens E5 has positive optical power, with its imaging side S9 being concave and its image source side S10 being convex. The sixth lens E6 has negative optical power, with its imaging side S11 being concave and its image source side S12 being convex. The image source side S14 is also present. Light from the image source side S15 passes sequentially through each surface S14 to S1 and is finally imaged onto the imaging surface STO.

[0041] Table 3 shows the surface type, radius of curvature, thickness, and material of each lens in the optical projection lens of Example 2, wherein the units for radius of curvature and thickness are millimeters (mm).

[0042] Table 3

[0043] In Table 3, the imaging side and image source side of any one of the lenses E1, E2, E3, E4, E5, and E6 are Q-type aspherical surfaces. The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0044] Where Z is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex of the surface, r is the radial coordinate of the aspherical surface, c is the curvature of the vertex of the aspherical surface, K is the conic coefficient, Am is the aspherical coefficient, and r max The maximum value of the radial radius coordinate is u = r / r max Table 4 provides the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 for each aspherical surface that can be used in the second embodiment.

[0045] Table 4

[0046] Example 3 The following is for reference Figures 5 to 6 Describes an optical projection lens according to Embodiment 3 of this application. Figure 5 A schematic diagram of the structure of an optical projection lens according to Embodiment 3 of this application is shown.

[0047] like Figure 5 As shown, the optical projection lens according to an exemplary embodiment of this application includes, in sequence along the optical axis from the imaging side to the image source side: imaging surface STO, first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, sixth lens E6 and image source surface S15.

[0048] The first lens E1 has negative focal power, its imaging side S1 is concave, and its image source side S2 is concave. The second lens E2 has positive focal power, its imaging side S3 is concave, and its image source side S4 is convex. The third lens E3 has positive focal power, its imaging side S5 is concave, and its image source side S6 is convex. The fourth lens E4 has negative focal power, its imaging side S7 is convex, and its image source side S8 is concave. The fifth lens E5 has positive focal power, its imaging side S9 is convex, and its image source side S10 is convex. The sixth lens E6 has negative focal power, its imaging side S11 is concave, and its image source side S12 is convex. The image side S14. The light from the image source plane 15 sequentially passes through each surface S14 to S1 and finally forms an image on the imaging plane STO.

[0049] Table 5 shows the surface type, radius of curvature, thickness and material of each lens of the optical projection lens of Example 3, wherein the units of the radius of curvature and thickness are millimeters (mm).

[0050] Table 5

[0051] In Table 5, any one of the imaging side and the image source side of the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5 and the sixth lens E6 is a Q-type aspheric surface, and the surface type of each aspheric lens can be defined by, but not limited to, the following aspheric surface formula:

[0052] wherein Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the radial coordinate of the aspheric surface, c is the curvature of the aspheric surface vertex, K is the conic coefficient, Am is the aspheric coefficient, r max is the maximum radial radius coordinate, and u = r / r max Table 6 shows the conic coefficient and the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 of each aspheric surface that can be used in the third embodiment.

[0053] Table 6

[0054] Example Four, The following refers to Figures 7 to 8 An optical projection lens according to Example 4 of the present application is described. Figure 7 A structural schematic diagram of the optical projection lens according to Example 4 of the present application is shown.

[0055] As Figure 7As shown, the optical projection lens according to the exemplary embodiment of the present application comprises, in order along the optical axis from the imaging side to the image source side: an imaging surface STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and an image source surface S15.

[0056] The first lens E1 has a negative focal power, with the imaging side surface S1 being concave and the image source side surface S2 being concave. The second lens E2 has a positive focal power, with the imaging side surface S3 being concave and the image source side surface S4 being convex. The third lens E3 has a positive focal power, with the imaging side surface S5 being concave and the image source side surface S6 being convex. The fourth lens E4 has a negative focal power, with the imaging side surface S7 being convex and the image source side surface S8 being concave. The fifth lens E5 has a positive focal power, with the imaging side surface S9 being concave and the image source side surface S10 being convex. The sixth lens E6 has a negative focal power, with the imaging side surface S11 being concave and the image source side surface S12 being convex. The image side surface S14. Light from the image source surface 15 passes through the surfaces S14 to S1 in order and is finally imaged on the imaging surface STO.

[0057] Table 7 shows the surface type, radius of curvature, thickness and material of each lens of the optical projection lens of Example 4, wherein the units of the radius of curvature and thickness are millimeters (mm).

[0058] Table 7

[0059] In Table 7, any one of the lens imaging side surface and the image source side surface of the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5 and the sixth lens E6 is a Q-type aspheric surface, and the surface type of each aspheric lens can be defined by, but not limited to, the following aspheric surface formula:

[0060] wherein Z is the distance from a corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the radial coordinate of the aspheric surface, c is the curvature of the aspheric surface vertex, K is the conic coefficient, Am is the aspheric coefficient, r max is the maximum radial radius coordinate, and u = r / r max Table 8 gives the conic coefficient and the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 of each aspheric surface that can be used in the fourth embodiment.

[0061] Table 8

[0062] In Examples 1-4, the basic data are as follows: Table 9

[0063] In the embodiments 1-4, each conditional expression satisfies the conditions of the following table: Table 10

[0064] The projection module at least comprises an optical lens, and the optical lens is internally mounted with the projection optical system. The projection optical system is configured by selecting one glass aspherical lens and five plastic aspherical lenses, and reasonably configuring the refractive power and surface shape of each lens. Field curvature, distortion and magnification chromatic aberration are effectively corrected, and a high-quality picture with bright edges and uniform resolution is obtained. In addition, the system adopts a front light barrier design, and strictly controls the existence of an air gap of more than 1 mm between the imaging surface and the first lens. The air gap can effectively converge the incident angle of the maximum field edge light, greatly reduce the off-axis aberration, thereby improving the clarity and uniformity of the entire image surface, and avoiding the blur or distortion of the picture edge. At the same time, the spacing provides valuable layout space for the mechanical structure of the lens barrel and the light shielding member. The spacing can effectively suppress stray light interference and improve the contrast of the system, relax the assembly tolerance between the lens edge and the lens barrel, reduce the production process difficulty and manufacturing cost, and enhance the engineering practicability and reliability of the design.

[0065] The above is one or more embodiments provided in combination with specific content, and it is not intended that the specific implementation of the present application is limited to these descriptions. Any approximation, similarity, or replacement of the method and structure of the present application, or any technical deduction or replacement under the premise of the concept of the present application, should be considered as the protection scope of the present application.

Claims

1. A projection optical system characterized by comprising: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are sequentially arranged along the optical axis from the imaging side to the image source side; The first lens has negative refractive power, and the imaging side surface thereof is a concave surface; The second lens has refractive power; The third lens has positive refractive power, and the image source side surface thereof is a convex surface; The fourth lens has refractive power, and the imaging side surface thereof is a convex surface; The fifth lens has positive refractive power, and the image source side surface thereof is a convex surface; The sixth lens has negative refractive power, and the imaging side surface thereof is a concave surface, and the image source side surface thereof is a convex surface; The optical system satisfies the following conditions: 1.4 mm < (FNO*f*ImgH) / TTL < 1.7 mm; Wherein, FNO is the F number of the optical system, f is the effective focal length of the optical system, ImgH is half of the diagonal length of the effective pixel area on the image source surface of the optical system, and TTL is the axial distance from the imaging side surface of the first lens of the optical system to the image source surface of the optical system.

2. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 3.0 / mm < TTL / (EPD*T01) < 4.0 / mm; Wherein, TTL is the axial distance from the imaging side surface of the first lens of the optical system to the image source surface of the optical system, EPD is the entrance pupil diameter of the optical system, and T01 is the axial distance from the imaging surface of the optical system to the imaging side surface of the first lens.

3. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 0.29 < DT62 / |R12| < 1; Wherein, R12 is the radius of curvature of the image source side surface of the sixth lens, and DT62 is the maximum effective radius of the image source side surface of the sixth lens.

4. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 14.0 < f*tan(HFOV) / |SAG1| < 20.0; and / or 1.0 < (CT1+CT6) / |SAG1+SAG12| < 2.0; Wherein, f is the effective focal length of the optical system, HFOV is half of the maximum field of view angle of the optical system, CT1 is the thickness of the first lens on the optical axis, CT6 is the thickness of the sixth lens on the optical axis, SAG1 is the distance from the maximum effective clear aperture of the imaging side surface of the first lens to the intersection point of the imaging side surface of the first lens and the optical axis in the direction parallel to the optical axis, and SAG12 is the distance from the maximum effective clear aperture of the image source side surface of the sixth lens to the intersection point of the image source side surface of the sixth lens and the optical axis in the direction parallel to the optical axis.

5. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 3.3 < ΣCT / CT3 < 6.0; Wherein, ΣCT is the sum of the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens on the optical axis of the optical system, and CT3 is the central thickness of the third lens on the optical axis.

6. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 15.5 < BFL / (T12+T23) < 18.5; Wherein, BFL is the shortest distance from the image source side surface of the sixth lens to the image source surface of the optical system in the direction of the optical axis, T12 is the air gap of the first lens and the second lens on the optical axis, and T23 is the air gap of the second lens and the third lens on the optical axis.

7. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 1.0 < |(f3-f1) / f3| < 3.0; wherein f1 is an effective focal length of the first lens, and f3 is an effective focal length of the third lens.

8. The projection optical system according to claim 1, characterized by: The optical system satisfies the following relationship: 1.6 < f / f345 < 1.9; and / or 2.2 < |(f23+f456) / f| < 5.0; wherein f is an effective focal length of the optical system, f345 is an effective combined focal length of the third lens, the fourth lens and the fifth lens, f23 is a combined focal length of the second lens and the third lens, and f456 is a combined focal length of the fourth lens, the fifth lens and the sixth lens.

9. The projection optical system according to claim 1, characterized by: The F number of the optical system is ≤ 1.89, and the total track length TTL satisfies: TTL ≤ 12 mm.

10. A projection module comprising at least an optical lens, characterized in that: The optical lens has the projection optical system according to any one of claims 1-9 installed therein.

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