Projection system

Abstract

The invention provides a projection system which comprises a light source, a collecting lens, a fly-eye lens, a first lens, a polarization splitting prism, an imaging lens group, a liquid crystal panel and a second lens, the projection system is further provided with a first optical axis and a second optical axis which are perpendicular to each other, and the first optical axis and the second optical axis are obliquely arranged relative to a light splitting surface of the polarization splitting prism; wherein the light source, the condenser, the fly-eye lens, the first lens and the polarization splitting prism are sequentially arranged along a first optical axis; the liquid crystal panel, the imaging lens group, the polarization splitting prism and the second lens are sequentially arranged along a second optical axis; the focal power of the first lens is positive, the focal power of the second lens is positive, the first lens and the second lens are convex plane lenses, and the imaging lens group comprises a third lens with negative focal power, a fourth lens with focal power and a fifth lens with positive focal power which are sequentially arranged from the beam splitter prism to the liquid crystal panel along the second optical axis. The projection system satisfies 1.04 < = f45 / fj < = 2.45.

Description

Technical Field

[0001] The present application relates to the technical field of optical devices, and in particular to a projection system. Background Art

[0002] With the continuous advancement of AR / VR technology, AR glasses have emerged in various technical solutions, including single-reflective, Birdbath, free-form prism, and waveguide. Waveguides offer the advantages of small size and light weight. Projection engines for waveguides include LCoS (Low-Current Array) and LED (Light Emitting Diode). LCoS projectors use a single-crystal silicon wafer as a substrate and utilize semiconductor manufacturing processes to create a driver panel (CMOS-LCD). Aluminum is plated on the transistors to serve as reflectors, forming the CMOS substrate. This is then bonded to a glass substrate containing transparent electrodes, and liquid crystal is injected and packaged. During operation, light from a light source illuminates the LCOS panel. The liquid crystal molecules change their alignment when voltage is applied, modulating the phase and intensity of the reflected light. The modulation state of the liquid crystal in different pixels corresponds to different grayscale and color information of the image. The modulated light is then reflected into the optical projection system, where, through complex optical components, the image is projected onto the waveguide or directly into the user's field of view.

[0003] In existing Lcos projector optical machines, a lens group for imaging is usually arranged on the light-emitting side of the polarization beam splitter prism. The illumination light path and the imaging light path are relatively independent, so the light propagation path is long. In actual use, the light loss is high and the picture brightness is low. If a laser light source with better coherence is used, the cost will be higher and the power consumption will increase accordingly, which is not conducive to improving the product's battery life. Summary of the Invention

[0004] One advantage of the present application is that it provides a projection system that can solve the adverse effects of a large air gap in a traditional fixed-focus lens on lens performance.

[0005] In one aspect, the present application provides a projection system comprising a light source, a condenser, a fly-eye lens, a first lens, a polarization beam splitter prism, an imaging lens group, a liquid crystal panel, and a second lens. The projection system further comprises a first optical axis and a second optical axis perpendicular to each other. The first optical axis and the second optical axis are respectively arranged at an angle relative to a beam splitting plane of the polarization beam splitter prism. A side along the second optical axis away from the liquid crystal panel is a first side, and a side along the second optical axis closer to the liquid crystal panel is a second side.

[0006] The light source, the condenser, the fly-eye lens, the first lens and the polarization beam splitter prism are arranged in sequence along the first optical axis;

[0007] The liquid crystal panel, the imaging lens group, the polarization beam splitter prism and the second lens are arranged in sequence along the second optical axis;

[0008] The light source is used to emit an original light beam, the condenser is used to convert the original light beam into a collimated light beam, the fly-eye lens is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism is used to reflect the homogenized light beam on the beam splitting surface and transmit the image light beam;

[0009] The first lens has positive refractive power, the second lens has positive refractive power, and both the first lens and the second lens are convex-planar lenses;

[0010] The imaging lens group includes a third lens, a fourth lens, and a fifth lens in order from the first side to the second side along the second optical axis; the third lens has negative optical power, a first side of the third lens is concave, and a second side of the third lens is concave; the fourth lens has optical power, a first side of the fourth lens is convex; the fifth lens has positive optical power, and a first side of the fifth lens is convex;

[0011] The projection system further satisfies the following condition: 1.04≤f45 / fj≤2.45; wherein f45 is the combined focal length of the fourth lens and the fifth lens, and fj is the focal length of the condenser lens.

[0012] In some embodiments of the present application, the first lens and the second lens are respectively glass spherical lenses, and the refractive index of the third lens is the largest among the first lens, the second lens, the third lens, the fourth lens, and the fifth lens.

[0013] In some embodiments of the present application, the condenser has positive optical power, the side of the condenser close to the polarization beam splitter prism is convex, the side of the condenser close to the light source is concave, and the fly-eye lens is a plastic lens; the center thickness of the fly-eye lens on the first optical axis is greater than the center thickness of the first lens on the first optical axis.

[0014] In some embodiments of the present application, the projection system further satisfies: 2.75<CTj / CT1<3.35; wherein CTj is the center thickness of the condenser on the first optical axis, and CT1 is the center thickness of the first lens on the first optical axis.

[0015] In some embodiments of the present application, the projection system further satisfies: -1.11≤R1 / R5≤-0.36; wherein R1 is the curvature radius of the light incident surface of the first lens, and R5 is the curvature radius of the first side of the third lens.

[0016] In some embodiments of the present application, the projection system further satisfies: 0.9<f1 / f45<1.85; wherein f1 is the focal length of the first lens, and f45 is the combined focal length of the fourth lens and the fifth lens.

[0017] In some embodiments of the present application, the projection system further satisfies: 0.91≤|f3+f4+f5| / f2≤2.25; wherein f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f2 is the focal length of the second lens.

[0018] In some embodiments of the present application, the projection system further satisfies: 0.75≤(CT3+CT4) / CT5≤1.25; wherein CT3 is the center thickness of the third lens on the second optical axis, CT4 is the center thickness of the fourth lens on the second optical axis, and CT5 is the center thickness of the fifth lens on the second optical axis.

[0019] In some embodiments of the present application, the projection system further satisfies the following: 3.85≤(T34+T45) / CT2≤4.94; wherein, T34 is the on-axis distance from the second side surface of the third lens to the first side surface of the fourth lens on the second optical axis, T45 is the on-axis distance from the second side surface of the fourth lens to the first side surface of the fifth lens on the second optical axis, and CT2 is the center thickness of the second lens on the second optical axis.

[0020] In some embodiments of the present application, the projection system further satisfies: 0.30≤|(R7+R8) / (R9+R10)|≤1.00; wherein R7 is the curvature radius of the first side of the fourth lens, R8 is the curvature radius of the second side of the fourth lens, R9 is the curvature radius of the first side of the fifth lens, and R10 is the curvature radius of the second side of the fifth lens.

[0021] In some embodiments of the present application, the projection system further satisfies: -1.45≤fj / f3≤-0.72; wherein fj is the focal length of the condenser lens, and f3 is the focal length of the third lens.

[0022] In some embodiments of the present application, the projection system further satisfies: 2.20≤f5 / CT5≤8.00; wherein f5 is the focal length of the fifth lens, and CT5 is the center thickness of the fifth lens on the second optical axis.

[0023] In summary, in the projection system provided by the present application, the condenser, the fly-eye lens, the first lens, the polarization beam splitter prism, the imaging lens group and the liquid crystal panel constitute the illumination lens group, the imaging lens group, the polarization beam splitter prism and the second lens constitute the imaging lens group, and the illumination lens group and the lens group share some optical components: the polarization beam splitter prism and the imaging lens group; by controlling the combined focal length f45 of the fourth lens and the fifth lens and the focal length fj of the condenser to satisfy 1.04≤f45 / fj≤2.45, while controlling the distance between the condenser and the light source to be reasonable, the light is made to directly enter the imaging lens group after the first reflection, and the converging effect of the imaging lens group on the light can guide the light to the liquid crystal panel, which is beneficial to reduce the light loss and stray light problems caused by light divergence. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of the projection system in Example 1 provided in this application;

[0025] Figure 2 Based on Figure 1 Provided are optical modulation function graphs of the projection system at different fields of view in the meridional direction;

[0026] Figure 3 This is a schematic diagram of the structure of the projection system in Example 2 provided in this application;

[0027] Figure 4 Based on Figure 3 Provided are optical modulation function graphs of the projection system at different fields of view in the meridional direction;

[0028] Figure 5 This is a schematic diagram of the structure of the projection system in Example 3 provided in this application;

[0029] Figure 6 Based on Figure 5 Provided are optical modulation function graphs of the projection system at different fields of view in the meridional direction;

[0030] Figure 7 Schematic diagram of the optical path of the projection system provided according to the present application. DETAILED DESCRIPTION

[0031] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of the present application and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of this application.

[0033] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0034] In this document, the paraxial region refers to the area near the optical axis. If the lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface shape in the paraxial region can be determined according to common methods in the art, for example, by determining whether it is concave or convex based on the positive or negative R value (R refers to the radius of curvature of the paraxial region). In this document, on the second optical axis, the side away from the liquid crystal panel is the first side, and the side closer to the liquid crystal panel is the second side. For the first side, when the R value is positive, it is judged to be a convex surface, and when the R value is negative, it is judged to be a concave surface. For the second side, when the R value is positive, it is judged to be a concave surface, and when the R value is negative, it is judged to be a convex surface. On the first optical axis, the side close to the light source is the light incident surface, and the side away from the light source is the light exit surface. For the light incident surface, when the R value is positive, it is judged to be a convex surface, and when the R value is negative, it is judged to be a concave surface. For the light exit surface, when the R value is positive, it is judged to be a concave surface, and when the R value is negative, it is judged to be a convex surface.

[0035] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0036] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The following examples only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they should not be understood as limiting the scope of the patent of this application. It should be pointed out that for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all fall within the scope of protection of the present application. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0038] According to one aspect of this application, Figure 1 As shown, one embodiment of the present application provides a projection system, including a light source, a condenser lens Ej, a fly-eye lens Ef, a first lens E1, a polarization beam splitter prism PBS, an imaging lens group, a liquid crystal panel, and a second lens E2. The projection system further has a first optical axis Z1 and a second optical axis Z2 that are perpendicular to each other. The first optical axis Z1 and the second optical axis Z2 are respectively arranged obliquely with respect to the splitting plane of the polarization beam splitter prism PBS. The side along the second optical axis Z2 away from the liquid crystal panel is a first side, and the side along the second optical axis Z2 close to the liquid crystal panel is a second side.

[0039] The light source, the condenser Ej, the fly-eye lens Ef, the first lens E1 and the polarization beam splitter prism PBS are arranged in sequence along the first optical axis Z1;

[0040] The liquid crystal panel, the imaging lens group, the polarization beam splitter prism PBS and the second lens E2 are arranged in sequence along the second optical axis Z2;

[0041] The light source is used to emit an original light beam, the condenser Ej is used to convert the original light beam into a collimated light beam, the fly-eye lens Ef is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism PBS is used to reflect the homogenized light beam on the splitting surface and transmit the image light beam;

[0042] The first lens E1 has positive refractive power, the second lens E2 has positive refractive power, and both the first lens E1 and the second lens E2 are convex-planar lenses;

[0043] The imaging lens group includes, in order from the first side to the second side along the second optical axis Z2, a third lens E3, a fourth lens E4, and a fifth lens E5; the third lens E3 has negative refractive power, a first side of the third lens E3 is concave, and a second side of the third lens E3 is concave; the fourth lens E4 has refractive power, a first side of the fourth lens E4 is convex; the fifth lens E5 has positive refractive power, and a first side of the fifth lens E5 is convex;

[0044] The projection system further satisfies the following condition: 1.04≤f45 / fj≤2.45; wherein f45 is the combined focal length of the fourth lens E4 and the fifth lens E5, and fj is the focal length of the condenser lens Ej.

[0045] In the projection system provided by the present application, a condenser Ej, a fly-eye lens Ef, a first lens E1, a polarization beam splitter prism PBS, an imaging lens group and a liquid crystal panel constitute an illumination lens group, and the imaging lens group, the polarization beam splitter prism PBS and the second lens E2 constitute an imaging lens group. The illumination lens group and the lens group share some optical components: the polarization beam splitter prism PBS and the imaging lens group control the combined focal length f45 of the fourth lens E4 and the fifth lens E5 to satisfy 1.04≤f45 / fj≤2.45 with the focal length fj of the condenser. While controlling the distance between the condenser Ej and the light source to be reasonable, the light is allowed to directly enter the imaging lens group after the first reflection. The converging effect of the imaging lens group on the light can guide the light to the liquid crystal panel, which is beneficial to reducing the light loss and stray light problems caused by light divergence.

[0046] According to some embodiments of the present application, the first lens E1 and the second lens E2 are respectively glass spherical lenses, and among the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, and the fifth lens E5, the third lens E3 has the largest refractive index.

[0047] In this way, by limiting the optical power and shape of the first lens E1 and the second lens E2 to convex-planar lenses, the illumination lens group, except for the condenser Ej and the fly-eye lens Ef, is essentially the same as the imaging lens group, thereby reducing the design difficulty of the fly-eye lens Ef and the condenser Ej in the illumination lens group.

[0048] According to some embodiments of the present application, the condenser Ej has positive optical power, the side of the condenser Ej close to the polarization beam splitter prism PBS is convex, the side of the condenser Ej close to the light source is concave, and the fly-eye lens Ef is a plastic lens; the center thickness of the fly-eye lens Ef on the first optical axis Z1 is greater than the center thickness of the first lens E1 on the first optical axis Z1.

[0049] In this way, by designing the optical focal length and surface shape of the condenser Ej and the compound eye lens Ef in the lighting mirror group, the propagation direction of the light emitted by the light source tends to be parallel after passing through them, and the light intensity at different angles tends to be consistent, thereby improving the uniformity of illumination.

[0050] According to some embodiments of the present application, the projection system further satisfies: 2.75<CTj / CT1<3.35; wherein CTj is the center thickness of the condenser Ej on the first optical axis Z1, and CT1 is the center thickness of the first lens E1 on the first optical axis Z1.

[0051] In this way, by controlling the ratio between the center thicknesses of the condenser lens Ej and the first lens E1 on the first optical axis Z1, the overall size of the optical system can be reduced to make it lighter and thinner.

[0052] Preferably, the projection system satisfies: 2.77≤CTj / CT1≤3.33.

[0053] According to some embodiments of the present application, the projection system further satisfies: -1.11≤R1 / R5≤-0.36; wherein R1 is the curvature radius of the light incident surface of the first lens E1, and R5 is the curvature radius of the first side of the third lens E3.

[0054] In this way, by controlling the ratio between the curvature radius of the first lens E1 and the curvature radius of the third lens E3, the processability of the lens is improved and the production cost is reduced.

[0055] According to some embodiments of the present application, the projection system further satisfies: 0.9<f1 / f45<1.85; wherein f1 is the focal length of the first lens E1, and f45 is the combined focal length of the fourth lens E4 and the fifth lens E5.

[0056] In this way, by controlling the ratio between the focal length of the first lens E1 and the combined focal lengths of the fourth lens E4 and the fifth lens E5, the sensitivity of the entire projection system at the first lens E1, the fourth lens E4 and the fifth lens E5 can be reduced, thereby improving the production yield.

[0057] Preferably, the projection system satisfies: 0.92≤f1 / f45≤1.84.

[0058] According to some embodiments of the present application, the projection system further satisfies: 0.91≤|f3+f4+f5| / f2≤2.25; wherein f3 is the focal length of the third lens E3, f4 is the focal length of the fourth lens E4, f5 is the focal length of the fifth lens E5, and f2 is the focal length of the second lens E2.

[0059] In this way, reasonably controlling the ratio of the absolute value of the sum of the focal lengths of all lenses in the imaging lens group to the focal length of the second lens E2 is beneficial to improving the illumination quality and imaging quality of the projection system provided by each lens.

[0060] According to some embodiments of the present application, the projection system further satisfies the following: 0.75≤(CT3+CT4) / CT5≤1.25; wherein CT3 is the center thickness of the third lens E3 on the second optical axis Z2, CT4 is the center thickness of the fourth lens E4 on the second optical axis Z2, and CT5 is the center thickness of the fifth lens E5 on the second optical axis Z2.

[0061] In this way, by reasonably controlling the range of this conditional formula, the processability of the lens can be improved while reducing the total length of the system, making it lighter and thinner.

[0062] According to some embodiments of the present application, the projection system further satisfies the following: 3.85≤(T34+T45) / CT2≤4.94; wherein T34 is the on-axis distance from the second side surface of the third lens E3 to the first side surface of the fourth lens E4 on the second optical axis Z2, T45 is the on-axis distance from the second side surface of the fourth lens E4 to the first side surface of the fifth lens E5 on the second optical axis Z2, and CT2 is the center thickness of the second lens E2 on the second optical axis Z2.

[0063] In this way, the range of this conditional formula can be reasonably controlled to ensure that there is no interference between lenses during product assembly, thereby improving product processability.

[0064] According to some embodiments of the present application, the projection system further satisfies the following condition: 0.30≤|(R7+R8) / (R9+R10)|≤1.00; wherein R7 is the curvature radius of the first side of the fourth lens E4, R8 is the curvature radius of the second side of the fourth lens E4, R9 is the curvature radius of the first side of the fifth lens E5, and R10 is the curvature radius of the second side of the fifth lens E5.

[0065] In this way, by reasonably controlling the range of this conditional expression, the contribution of the fourth lens element E4 and the fifth lens element E5 to imaging is increased, and the imaging performance is improved while ensuring its workability.

[0066] According to some embodiments of the present application, the projection system further satisfies: -1.45≤fj / f3≤-0.72; wherein fj is the focal length of the condenser Ej, and f3 is the focal length of the third lens E3.

[0067] In this way, the range of this conditional expression can be reasonably controlled so that the propagation direction of the light emitted by the light source tends to be parallel after passing through the condenser Ej, while controlling the distance between the light source and the condenser Ej.

[0068] According to some embodiments of the present application, the projection system further satisfies: 2.20≤f5 / CT5≤8.00; wherein f5 is the focal length of the fifth lens E5, and CT5 is the center thickness of the fifth lens E5 on the second optical axis Z2.

[0069] In this way, the range of this conditional expression is reasonably controlled, the contribution of the fifth lens element E5 to imaging is increased, and imaging performance is improved while ensuring its workability.

[0070] Some specific but non-limiting examples of the above-mentioned embodiments of the present application are described in more detail below with reference to the accompanying drawings. For ease of description, in the following embodiments, STO represents the surface of the aperture, S1 represents the first side of the second lens E2, S2 represents the second side of the second lens E2, S3 represents the first side of the polarization splitter prism PBS, S4 represents the second side of the polarization splitter prism PBS, S5 represents the first side of the quarter-wave plate QWP, S6 represents the second side of the quarter-wave plate QWP, S7 represents the first side of the third lens E3, S8 represents the second side of the third lens E3, S9 represents the first side of the fourth lens E4, S10 represents the second side of the fourth lens E4, S11 represents the first side of the fifth lens E5, S12 represents the second side of the fifth lens E5, S13 represents the first side of the flat glass, S14 represents the second side of the flat glass, and S15 represents the reflective surface of the liquid crystal panel; K1 represents the light incident surface of the condenser lens Ej, K2 represents the light exit surface of the condenser lens Ej, K3 represents the light incident surface of the fly-eye lens Ef, K4 represents the light exit surface of the fly-eye lens Ef, K5 represents the light incident surface of the first lens E1, and K6 represents the light exit surface of the first lens E1. In addition, Aj represents the j-th order aspheric coefficient, j=4, 6, 8, 10, 12, 14, 16, 18, 20.

[0071] Specific optical path Figure 7 As shown, in the present application, in the direction of the first optical axis Z1, a linear polarizer LP is provided between the polarization splitter prism PBS and the first lens E1, and in the direction of the second optical axis Z2, a quarter-wave plate QWP is provided between the polarization splitter prism and the third lens E3, wherein the quarter-wave plate QWP is glued to the polarization splitter prism PBS, and the specific optical path is as follows: the light emitted by the light source passes through the condenser Ej, the fly-eye lens Ef and the first lens E1 in sequence, and then is filtered by the linear polarizer LP at the light incident surface of the polarization splitter prism PBS and enters the polarization splitter prism PBS in the form of linearly polarized light. After being reflected by the splitting surface, the linearly polarized light passes through the quarter-wave plate QWP and passes through the third lens E3, the fourth lens E4, and the fifth lens E5 of the imaging lens group in sequence along the second optical axis Z2, and then is reflected at the liquid crystal panel and converted in polarization angle, and returns along the original optical path in the direction of the second optical axis, passes through the fifth lens E5, the fourth lens E4, the third lens E3, the quarter-wave plate QWP in sequence, passes through the second lens E2 and is emitted from the aperture surface.

[0072] Example 1

[0073] like Figure 1 As shown, in this embodiment, the projection system includes a light source, a condenser Ej, a fly-eye lens Ef, a first lens E1, a polarization beam splitter prism, an imaging lens group, a liquid crystal panel and a second lens E2. The projection system also has a first optical axis Z1 and a second optical axis Z2 that are perpendicular to each other. The first optical axis Z1 and the second optical axis Z2 are respectively arranged at an angle to the beam splitting surface of the polarization beam splitter prism PBS; wherein the light source, the condenser Ej, the fly-eye lens Ef, the first lens E1 and the polarization beam splitter prism PBS are arranged in sequence along the first optical axis Z1; the liquid crystal panel, the imaging lens group, the polarization beam splitter prism PBS and the second lens E2 are arranged in sequence along the second optical axis Z2; the light source is used to emit an original light beam, the condenser Ej is used to convert the original light beam into a collimated light beam, the fly-eye lens Ef is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism PBS is used to reflect the homogenized light beam on the beam splitting surface and transmit the image light beam.

[0074] In this embodiment, the condenser Ej has positive focal power, the light incident surface K1 of the condenser Ej is concave, and the light exit surface K2 of the condenser Ej is convex. The first lens E1 has positive focal power, the light incident surface K5 of the first lens E1 is convex, and the light exit surface K6 of the first lens E1 is flat. The second lens E2 has positive focal power, the first side S1 of the second lens E2 is convex, and the second side S2 of the second lens E2 is flat. The third lens E3 has negative focal power, the first side S7 of the third lens E3 is concave, and the second side S8 of the third lens E3 is concave. The fourth lens E4 has positive focal power, the first side S9 of the fourth lens E4 is convex, and the second side S10 of the fourth lens E4 is convex. The fifth lens E5 has positive focal power, the first side S11 of the fifth lens E5 is convex, and the second side S12 of the fifth lens E5 is concave.

[0075] In addition, Tables 1 to 4 respectively show the basic optical parameters of the projection system of Example 1, wherein the units of the curvature radius and thickness / distance are all millimeters (mm).

[0076] Table 1: Basic optical parameters of the condenser Ej in the projection system of Example 1

[0077]

[0078] Table 2: Basic optical parameters of the fly-eye lens Ef in the projection system of Example 1

[0079]

[0080] Table 3: Basic optical parameters of the first lens E1 in the projection system of Example 1

[0081]

[0082] Table 4: Basic optical parameters of the partial structure of the projection system of Example 1

[0083]

[0084] In this embodiment, both the object-side surface and the image-side surface of any one of the fourth lens element E4 and the fifth lens element E5 are aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0085] ;

[0086] Where x is the distance from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient for the i-th order of the aspheric surface. Table 5 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspheric mirror surface S9 to S12 in Example 1.

[0087] Table 5: Aspheric coefficients in the projection system of Example 1

[0088]

[0089] like Figure 2 As shown, Figure 2 Based on Figure 1 The provided optical modulation function curves for the projection system at different fields of view in the meridional direction show that when the optical frequency varies from 0 to 25, the optical modulation function values at multiple fields of view in the meridional direction are greater than 0.75, indicating that the projection system in this embodiment has good imaging quality.

[0090] Example 2

[0091] like Figure 3As shown, in this embodiment, the projection system includes a light source, a condenser Ej, a fly-eye lens Ef, a first lens E1, a polarization beam splitter prism PBS, an imaging lens group, a liquid crystal panel and a second lens E2. The projection system also has a first optical axis Z1 and a second optical axis Z2 that are perpendicular to each other. The first optical axis Z1 and the second optical axis Z2 are respectively arranged at an angle to the beam splitting surface of the polarization beam splitter prism PBS; wherein the light source, the condenser Ej, the fly-eye lens Ef, the first lens E1 and the polarization beam splitter prism PBS are arranged in sequence along the first optical axis Z1; the liquid crystal panel, the imaging lens group, the polarization beam splitter prism PBS and the second lens E2 are arranged in sequence along the second optical axis Z2; the light source is used to emit an original light beam, the condenser Ej is used to convert the original light beam into a collimated light beam, the fly-eye lens Ef is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism PBS is used to reflect the homogenized light beam on the beam splitting surface and transmit the image light beam.

[0092] In this embodiment, the condenser Ej has positive focal power, a light incident surface K1 of the condenser Ej is concave, and a light exit surface K2 of the condenser Ej is convex. The first lens E1 has positive focal power, a light incident surface K5 of the first lens E1 is convex, and a light exit surface K6 of the first lens E1 is flat. The second lens E2 has positive focal power, a first side S1 of the second lens E2 is convex, and a second side S2 of the second lens E2 is flat. The third lens E3 has negative focal power, a first side S7 of the third lens E3 is concave, and a second side S8 of the third lens E3 is concave. The fourth lens E4 has negative focal power, a first side S9 of the fourth lens E4 is convex, and a second side S10 of the fourth lens E4 is concave. The fifth lens E5 has positive focal power, a first side S11 of the fifth lens E5 is convex, and a second side S12 of the fifth lens E5 is convex.

[0093] In addition, Tables 6 to 9 respectively show the basic optical parameters of the projection system of Example 2, wherein the units of the curvature radius and thickness / distance are all millimeters (mm).

[0094] Table 6: Basic optical parameters of the condenser lens Ej in the projection system of Example 2

[0095]

[0096] Table 7: Basic optical parameters of the fly-eye lens Ef in the projection system of Example 2

[0097]

[0098] Table 8: Basic optical parameters of the first lens E1 in the projection system of Example 2

[0099]

[0100] Table 9: Basic optical parameters of the partial structure of the projection system of Example 2

[0101]

[0102] In this embodiment, both the object-side surface and the image-side surface of any one of the fourth lens element E4 and the fifth lens element E5 are aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0103] ;

[0104] Where x is the distance from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspheric surface. Table 10 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspheric mirror surface S9 to S12 in Example 1.

[0105] Table 10: Aspheric coefficients in the projection system of Example 2

[0106]

[0107] like Figure 4 As shown, Figure 4 Based on Figure 3 The provided optical modulation function curves for the projection system at different fields of view in the meridional direction show that when the optical frequency varies between 0 and 25, the optical modulation function curves for different fields of view in the meridional direction are all greater than 0.9, indicating that the projection system in this embodiment has good imaging quality.

[0108] Example 3

[0109] like Figure 5As shown, in this embodiment, the projection system includes a light source, a condenser Ej, a fly-eye lens Ef, a first lens E1, a polarization beam splitter prism PBS, an imaging lens group, a liquid crystal panel and a second lens E2. The projection system also has a first optical axis Z1 and a second optical axis Z2 that are perpendicular to each other. The first optical axis Z1 and the second optical axis Z2 are respectively arranged at an angle to the beam splitting surface of the polarization beam splitter prism PBS; wherein the light source, the condenser Ej, the fly-eye lens Ef, the first lens E1 and the polarization beam splitter prism PBS are arranged in sequence along the first optical axis Z1; the liquid crystal panel, the imaging lens group, the polarization beam splitter prism PBS and the second lens E2 are arranged in sequence along the second optical axis Z2; the light source is used to emit an original light beam, the condenser Ej is used to convert the original light beam into a collimated light beam, the fly-eye lens Ef is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism PBS is used to reflect the homogenized light beam on the beam splitting surface and transmit the image light beam.

[0110] In this embodiment, the condenser Ej has positive focal power, the light incident surface K1 of the condenser Ej is concave, and the light exit surface K2 of the condenser Ej is convex. The first lens E1 has positive focal power, the light incident surface K5 of the first lens E1 is convex, and the light exit surface K6 of the first lens E1 is flat. The second lens E2 has positive focal power, the first side S1 of the second lens E2 is convex, and the second side S2 of the second lens E2 is flat. The third lens E3 has negative focal power, the first side S7 of the third lens E3 is concave, and the second side S8 of the third lens E3 is concave. The fourth lens E4 has negative focal power, the first side S9 of the fourth lens E4 is convex, and the second side S10 of the fourth lens E4 is concave. The fifth lens E5 has positive focal power, the first side S11 of the fifth lens E5 is convex, and the second side S12 of the fifth lens E5 is concave.

[0111] In addition, Tables 11 to 14 respectively show the basic optical parameters of the projection system of Example 3, wherein the units of the curvature radius and thickness / distance are all millimeters (mm).

[0112] Table 11: Basic optical parameters of the condenser Ej in the projection system of Example 3

[0113]

[0114] Table 12: Basic optical parameters of the fly-eye lens Ef in the projection system of Example 3

[0115]

[0116] Table 13: Basic optical parameters of the first lens E1 in the projection system of Example 3

[0117]

[0118] Table 14: Basic optical parameters of the partial structure of the projection system of Example 3

[0119]

[0120] In this embodiment, both the object-side surface and the image-side surface of any one of the fourth lens element E4 and the fifth lens element E5 are aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0121] ;

[0122] Where x is the distance from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient for the i-th order of the aspheric surface. Table 15 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspheric mirror surface S9 to S12 in Example 1.

[0123] Table 15: Aspheric coefficients in the projection system of Example 3

[0124]

[0125] like Figure 6 As shown, Figure 6 Based on Figure 5 The provided optical modulation function curves for the projection system at different fields of view in the meridional direction show that when the optical frequency varies between 0 and 25, the optical modulation function curves for different fields of view in the meridional direction are all greater than 0.85, indicating that the projection system in this embodiment has good imaging quality.

[0126] In addition, the system optical parameter table of the projection system in Examples 1 to 3 is shown in Table 16.

[0127] Table 16: System optical parameters of projection system

[0128]

[0129] In summary, the projection systems in Examples 1 to 3 satisfy the relationship shown in Table 17, as shown in Table 17.

[0130] Table 17: Relationships satisfied by the projection system

[0131]

[0132] It is worth mentioning that, according to one aspect of the present application, one embodiment of the present application further provides a projection light engine, which may include the above-mentioned projection system and a photosensitive element, the photosensitive element being arranged on the light-emitting side of the projection system for imaging. It is understood that the photosensitive element mentioned in the present application may be implemented as, but not limited to, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and this application will not elaborate on this.

[0133] In addition, according to another aspect of the present application, one embodiment of the present application further provides an electronic device, which may include the above-mentioned projector and a processor, wherein the projector is communicatively connected to the processor to acquire image data and input the image data into the processor for processing. It is understood that the electronic device mentioned in this application may be implemented as, but not limited to, a device such as a mobile phone equipped with the projector, and this application will not elaborate on this.

[0134] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A projection system, characterized in that: The projection system comprises a light source, a condenser, a fly-eye lens, a first lens, a polarization beam splitter prism, an imaging lens group, a liquid crystal panel, and a second lens. The projection system further comprises a first optical axis and a second optical axis perpendicular to each other. The first optical axis and the second optical axis are respectively arranged obliquely with respect to the beam splitting plane of the polarization beam splitter prism. The side along the second optical axis away from the liquid crystal panel is a first side, and the side along the second optical axis close to the liquid crystal panel is a second side. The light source, the condenser, the fly-eye lens, the first lens and the polarization beam splitter prism are arranged in sequence along the first optical axis; The liquid crystal panel, the imaging lens group, the polarization beam splitter prism and the second lens are arranged in sequence along the second optical axis; The light source is used to emit an original light beam, the condenser is used to convert the original light beam into a collimated light beam, the fly-eye lens is used to convert the collimated light beam into a homogenized light beam, the liquid crystal panel is used to convert the homogenized light beam into an image light beam, and the polarization beam splitter prism is used to reflect the homogenized light beam on the beam splitting surface and transmit the image light beam; The first lens has positive refractive power, the second lens has positive refractive power, and both the first lens and the second lens are convex-planar lenses; The imaging lens group includes a third lens, a fourth lens, and a fifth lens in order from the first side to the second side along the second optical axis; the third lens has negative optical power, a first side of the third lens is concave, and a second side of the third lens is concave; the fourth lens has optical power, a first side of the fourth lens is convex; the fifth lens has positive optical power, and a first side of the fifth lens is convex; The projection system further satisfies the following condition: 1.04≤f45 / fj≤2.45, wherein f45 is the combined focal length of the fourth lens and the fifth lens, and fj is the focal length of the condenser lens.

2. The projection system according to claim 1, wherein: The first lens and the second lens are both glass spherical lenses. Among the first lens, the second lens, the third lens, the fourth lens and the fifth lens, the refractive index of the third lens is the largest.

3. The projection system according to claim 1, wherein: The condenser has positive focal power, the side of the condenser close to the polarization beam splitter prism is convex, the side of the condenser close to the light source is concave, and the fly-eye lens is a plastic lens; the center thickness of the fly-eye lens on the first optical axis is greater than the center thickness of the first lens on the first optical axis.

4. The projection system according to claim 1, wherein: The projection system also satisfies: 2.75<CTj / CT1<3.35; Wherein, CTj is the center thickness of the condenser on the first optical axis, and CT1 is the center thickness of the first lens on the first optical axis.

5. The projection system according to claim 1, wherein: The projection system also satisfies: -1.11≤R1 / R5≤-0.36; R1 is the curvature radius of the light incident surface of the first lens, and R5 is the curvature radius of the first side of the third lens.

6. The projection system according to claim 1, wherein: The projection system also satisfies: 0.9<f1 / f45<1.85; Wherein, f1 is the focal length of the first lens, and f45 is the combined focal length of the fourth lens and the fifth lens.

7. The projection system according to claim 1, wherein: The projection system further satisfies: 0.91≤|f3+f4+f5| / f2≤2.25; Among them, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f2 is the focal length of the second lens.

8. The projection system according to claim 1, wherein: The projection system also satisfies: 0.75≤(CT3+CT4) / CT5≤1.25; Wherein, CT3 is the center thickness of the third lens on the second optical axis, CT4 is the center thickness of the fourth lens on the second optical axis, and CT5 is the center thickness of the fifth lens on the second optical axis.

9. The projection system according to claim 1, wherein: The projection system also satisfies: 3.85≤(T34+T45) / CT2≤4.94; Wherein, T34 is the on-axis distance from the second side surface of the third lens to the first side surface of the fourth lens on the second optical axis, T45 is the on-axis distance from the second side surface of the fourth lens to the first side surface of the fifth lens on the second optical axis, and CT2 is the center thickness of the second lens on the second optical axis.

10. The projection system according to claim 1, wherein: The projection system further satisfies: 0.30≤|(R7+R8) / (R9+R10)|≤1.00; Among them, R7 is the curvature radius of the first side of the fourth lens, R8 is the curvature radius of the second side of the fourth lens, R9 is the curvature radius of the first side of the fifth lens, and R10 is the curvature radius of the second side of the fifth lens.

11. The projection system according to claim 1, wherein: The projection system also satisfies: -1.45≤fj / f3≤-0.72; Wherein, fj is the focal length of the condenser lens, and f3 is the focal length of the third lens.

12. The projection system according to claim 1, wherein: The projection system also satisfies: 2.20≤f5 / CT5≤8.00; Wherein, f5 is the focal length of the fifth lens, and CT5 is the center thickness of the fifth lens on the second optical axis.

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