TW202221378A - Projection lens and projection apparatus - Google Patents

Abstract

A projection lens includes a first lens group, a second lens group and an aperture stop. The first lens group is disposed between a reduced side and a magnified side. The second lens is disposed between the first lens group and the magnified side. The second lens group has a light incident surface, a reflective surface and a light emitting surface, the light incident surface faces the first lens group, the light emitting surface faces a projection surface, the light incident surface, the light emitting surface and the first lens group are disposed at a single side of the reflective surface, and at least one of the light incident surface, the reflective surface and the light emitting surface is a freeform surface. The aperture stop is disposed between the first lens group and the second lens group. A light valve is adopted to provide an image light beam. A first optical axis of the first lens group and a center of the image light beam aren't overlapped. Moreover, a projection apparatus including the projection lens is also provided.

Description

Projection lens and projection device

The present invention relates to an optical lens and an optical device, and more particularly, to a projection lens and a projection device.

Projectors have been widely used in home appliances, office equipment, game consoles, etc. The demand for projectors is gradually developing towards thin and small size. For example, compared to projectors using conventional light sources, pocket-type projectors using light-emitting diodes are small in size and light in weight, which can reduce space requirements and are easy to carry.

In practical application, in order to reduce the usage space of the projector, it is necessary to modify the mechanism of the projector to change the traditional vertical projection to the oblique projection, so that the projection picture can be turned through the reflector, and the turned projection head picture can be projected as required. to the projection surface (eg: desktop, floor, wall, screen, etc.). In the oblique projection structure, the reference ray of the outgoing light from the projector cannot be perpendicular to the projection surface, that is, oblique incidence, which will cause keystone distortion of the projection image. Traditionally, in order to improve the keystone distortion, software can be used to crop the distorted area of the projected image, so as to achieve no distortion. However, this software correction method will lead to a reduction in resolution and a loss of brightness. In addition, another way to improve the keystone distortion is hardware correction, that is, to move the projection lens to the direction, however, this method will cause the projector to become larger.

The present invention provides a projection lens, which is small in size and can improve keystone distortion.

The present invention provides a projection device with small volume and capable of improving keystone distortion.

The projection lens of the present invention is suitable for imaging the light valve arranged on the reduction side on the projection surface arranged on the enlargement side. The light valve is at an angle to the projection surface. The projection lens includes a first mirror group, a second mirror group and a diaphragm. The first lens group is disposed between the reduction side and the enlargement side and has a first optical axis. The second mirror group is disposed between the first mirror group and the magnifying side, wherein the second mirror group has at least a light incident surface, a reflection surface and a light exit surface, the light incident surface faces the first mirror group, the light exit surface faces the projection surface, and the light incident surface faces the projection surface. The surface, the light emitting surface and the first mirror group are arranged on the same side of the reflective surface, and at least one of the light incident surface, the reflective surface and the light emitting surface is a free-form surface. The diaphragm is arranged between the first mirror group and the second mirror group. The light valve is adapted to provide the image beam. The image beam sequentially passes through the first mirror group, passes through the aperture, passes through the light incident surface of the second mirror group, is reflected by the reflective surface of the second mirror group, and passes through the light exit surface of the second mirror group to be transmitted to the projection. noodle. The first optical axis of the first lens group does not overlap with the center of the image beam.

The projection device of the present invention includes an illumination light source, a light valve, a projection surface and the above-mentioned projection lens. The illumination light source is adapted to provide an illumination beam. The light valve is arranged on the reduction side and is suitable for converting the illumination light beam into the image light beam. The projection surface is arranged on the magnifying side, wherein the light valve and the projection surface have an angle.

In an embodiment of the present invention, the above-mentioned second mirror group includes a turning point, and the turning point has a light incident surface, a reflection surface and a light output surface.

In an embodiment of the present invention, the above-mentioned first lens group includes a plurality of lenses arranged in sequence from the magnifying side to the reducing side, and each lens has a first surface facing the second lens group and a second lens facing the light valve. surface, and the first surface of the lens closest to the diaphragm among the plurality of lenses is a free-form surface.

In an embodiment of the present invention, the above-mentioned diaphragm and the reflecting surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, the image beam includes a first edge ray and a second edge ray, the first An edge ray exits from a point on the edge of the light valve in a direction away from the first optical axis, and a second edge ray exits from this point on the edge of the light valve in a direction toward the first optical axis, in the first mirror group The first edge ray and the first optical axis have a maximum distance H1 in the direction perpendicular to the first optical axis, and the second edge ray and the first optical axis on the light-emitting surface of the second mirror group are perpendicular to the first optical axis. There is a maximum distance H2 in the direction of the axis, and (H1+H2)/D<3.

In an embodiment of the present invention, the above-mentioned diaphragm and the reflecting surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, the light exit surface of the second mirror group has an optical effective diameter CA, and CA/D<3.

In an embodiment of the present invention, the above-mentioned image light beam has an offset value relative to the first optical axis of the first lens group.

In an embodiment of the present invention, the above-mentioned angle is θ, and 25o<θ<90o.

In an embodiment of the present invention, the above-mentioned image beams form a projection picture on the projection surface, the opposite sides of the projection picture are parallel to each other and have lengths A and B respectively in one direction, and the projection picture has the maximum length in the direction. Width W, [(B-A)/W]‧100%=T, and |T|＜1%.

Based on the above, in the projection device and the projection lens according to an embodiment of the present invention, at least one of the light incident surface, the reflection surface and the light output surface of the second mirror group of the projection lens is a free-form surface, and the first mirror group of the first mirror group is a free-form surface. The optical axis does not overlap the center of the image beam. Thereby, the design of the common optical path back and forth can be realized, thereby reducing the overall thickness of the projection lens. In addition, since at least one of the light incident surface, the reflection surface and the light output surface of the second mirror group is a free-form surface, the projection lens can also make the focal length of the image beam corresponding to each viewing angle different, thereby improving the trapezoidal distortion phenomenon.

The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or rear, etc., are only for referring to the directions of the attached drawings. Accordingly, the directional terms used are illustrative and not limiting of the present invention.

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts.

FIG. 1 is a schematic side view of a projection apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged schematic view of a light valve, a protective cover, a light combining element, a plate glass actuator and a projection lens of the projection apparatus of FIG. 1 .

Please refer to FIG. 1 and FIG. 2 , the direction z in the figures is, for example, a direction perpendicular to the projection surface PS, the direction y is, for example, a direction parallel to the projection surface PS, and the direction x is, for example, parallel to the projection surface PS and perpendicular to the direction y direction.

Referring to FIG. 1 , the projection apparatus 100 includes an illumination light source ILS, a light valve LV, a projection lens PL and a projection surface PS. The projection lens PL has a reduction side and an enlargement side. The light valve LV is arranged on the reduction side. The projection surface PS is arranged on the enlargement side. The illumination light source ILS is adapted to provide the illumination light beam ILB. The light valve LV is adapted to convert the illumination beam ILB into the image beam IMB. The projection lens PL is adapted to image the image beam IMB from the light valve LV on the projection surface PS on the magnifying side. In particular, the projection surface PS and the light valve LV have an included angle θ. In other words, the projection device 100 is an oblique projection device. The angle θ between the projection surface PS and the light valve LV satisfies: 0 ^o <θ<90 ^o . For example, the included angle θ may satisfy: 25 ^o <θ<90 ^o , but the present invention is not limited to this.

The projection surface PS generally refers to a surface of an object on which a projection image can be formed. For example, in this embodiment, the projection surface PS may be a desktop. However, the present invention is not limited thereto, and in other embodiments, the projection surface PS may also be a ground, a wall, a screen, or the like.

In this embodiment, the light valve LV can optionally be a reflective light modulator, such as a digital micro-mirror device, a liquid-crystal-on-silicon panel (LCOS panel) )Wait. However, the present invention is not limited thereto, and in other embodiments, the light valve LV can also be a transmissive light modulator, such as a transparent liquid crystal panel, an electro-optical modulator , Magneto-Optic modulator, Acousto-Optic Modulator (AOM), etc.

In the present embodiment, the projection apparatus 100 may optionally further include a light combining element PR. The illumination system ILS emits the illumination beam ILB to the light combining element PR, and the illumination light beam ILB is transmitted to the light valve LV through the light combining element PR. to the projection lens PL. For example, in this embodiment, the light combining element PR may be a Total Internal Reflection Prism (TIR Prism). However, the present invention is not limited thereto. In other embodiments, the light combining element PR may also be a beam splitter (beam splitter), a polarizer beam splitter (polarizer beam splitter), a field lens or other optical elements. It depends on the required light splitting or light guiding design, and is not limited by the present invention.

Referring to FIGS. 1 and 2 , in this embodiment, the projection device 100 may optionally include a protective cover CG (marked in FIG. 2 ), which is disposed on the light-receiving surface LVa (marked in FIG. 2 ) of the light valve LV, And it is located between the light valve LV and the light combining element PR. The protective cover CG is suitable for protecting the light valve LV. In addition, in this embodiment, the projection device 100 may optionally include a plate glass actuator AC, which may have a filter function.

The projection lens PL includes a first lens group LG1, an aperture AS and a second lens group LG2. The first lens group LG1 is disposed between the reduction side and the enlargement side and has a first optical axis X1. The second mirror group LG2 is disposed between the first mirror group LG1 and the magnifying side. The diaphragm AS is disposed between the first mirror group LG1 and the second mirror group LG2. The second mirror group LG2 has at least a light incident surface RP3, a reflection surface RP2 and a light exit surface RP1, wherein the light incident surface RP3 faces the first mirror group LG1, the light exit surface RP1 faces the projection surface PS, and the light incident surface RP3, the light exit surface RP1 and The first mirror group LG1 is arranged on the same side of the reflection surface RP2.

Referring to FIG. 2, the first lens group LG1 includes a plurality of lenses L1, L2, L3, L4, L5 sequentially arranged from the magnification side to the reduction side, wherein each lens L1, L2, L3, L4, L5 has a surface facing the The first surfaces L11, L21, L31, L41, L51 of the second mirror group LG2 and the second surfaces L12, L22, L32, L42, L52 facing the light valve LV.

For example, in this embodiment, the first lens group LG1 includes a lens L1, a lens L2, a lens L3, a lens L4 and a lens L5 which are arranged in sequence from the magnification side to the reduction side, wherein the lens L1 has a lens facing the second mirror The first surface L11 of the group LG2 and the second surface L12 facing the light valve LV, the lens L2 has a first surface L21 facing the second mirror group LG2 and the second surface L22 facing the light valve LV, the lens L3 has a second surface facing the second mirror The group LG2 has a first surface L31 and a second surface L32 facing the light valve LV, the lens L4 has a first surface L41 facing the second mirror group LG2 and a second surface L42 facing the light valve LV, and the lens L5 has a second surface L42 facing the light valve LV. The first surface L51 of the mirror group LG2 and the second surface L52 facing the light valve LV. In this embodiment, the number of the plurality of lenses L1 , L2 , L3 , L4 , and L5 of the first lens group LG1 is, for example, five. However, the present invention is not limited to this, and the number of lenses of the first mirror group LG1 can be changed according to actual requirements. In other embodiments, the number of lenses of the first mirror group LG1 may also be 2, 3, 4, 6 or a positive integer greater than 6. In this embodiment, the focal length of the first lens group LG1 may be a negative value, but the present invention is not limited to this.

Aperture AS refers to the entity that limits the image beam IMB in the projection lens PL, and the beam has the smallest cross-sectional area through the aperture AS, which can be the edge of the lens, a frame or a specially designed screen with holes. For example, in this embodiment, the aperture AS is, for example, a screen with apertures disposed between the first mirror group LG1 and the second mirror group LG2, but the invention is not limited to this. In this embodiment, the first surface L11 of one lens L1 closest to the aperture AS among the plurality of lenses L1 , L2 , L3 , L4 , and L5 of the first mirror group LG1 may be a free-form surface.

In this embodiment, the second mirror group LG2 may include a turning plane RP, and the turning plane RP has a light incident surface RP3, a reflection surface RP2, and a light output surface RP1. In this embodiment, the light incident surface RP3 of the turning plane RP can be a concave surface, and the light exit surface RP1 of the turning plane RP can be a convex surface.

It is worth noting that, at least one of the light incident surface RP3, the reflection surface RP2 and the light exit surface RP1 of the second mirror group LG2 is a free-form surface, and the first optical axis X1 of the first mirror group LG1 does not overlap the center of the image beam IMB IMBc. Thereby, a common optical path design can be realized, that is, the optical path of the image beam IMB transmitted from the first mirror group LG1 to the second mirror group LG2 and reflected by the reflecting surface RP2 of the second mirror group LG2 back to the first mirror group LG1 The optical paths of the image beam IMB can be coincident, and the image beam IMB reflected by the reflection surface RP2 of the second mirror group LG2 can have enough space to exit from the light incident surface RP3 of the second mirror group LG2. Since the projection lens PL has a common optical path design, the image beam IMB reflected by the reflection surface RP2 of the second mirror group LG2 back to the first mirror group LG1 is unlikely to cause interference, so the aperture AS and the reflection surface RP2 of the second mirror group LG2 are parallel to each other. The maximum distance D in the direction d1 of the first optical axis X1 can be shortened. When the maximum distance D is shortened, the optical effective diameter CA of the reflection surface RP2 of the second mirror group LG2 will not be too large. In this way, the overall thickness H of the projection lens PL can be reduced.

Referring to FIG. 2, the image beam IMB includes a first edge ray IMB1 and a second edge ray IMB2. The first edge ray IMB1 exits from a point LVp on the edge LVe of the light valve LV in a direction away from the first optical axis X1, and the second edge ray IMB1 The edge ray IMB2 exits from the point LVp on the edge LVe of the light valve LV toward the direction of the first optical axis X1. The first edge ray IMB1 in the first mirror group LG1 and the first optical axis X1 are perpendicular to the first optical axis X1. There is a maximum distance H1 in the direction d2 of the axis X1, and the second edge ray IMB2 on the light exit surface RP1 of the second mirror group LG2 has a maximum distance H2 with the first optical axis X1 in the direction d2 perpendicular to the first optical axis X1 , and the aforementioned overall thickness H of the projection lens PL refers to the sum of the maximum distance H1 and the maximum distance H2. For example, in this embodiment, the overall thickness H of the projection lens PL may be less than 12 mm, but the present invention is not limited to this.

The diaphragm AS and the reflection surface RP2 of the second mirror group LG2 have a maximum distance D in the direction d1 parallel to the first optical axis X1. In this embodiment, H/D<3. In addition, in this embodiment, the light-emitting surface RP1 of the second mirror group LG2 has an optical effective diameter CA, and CA/D<3. In other words, the ratio of the overall thickness H of the projection lens PL to the maximum distance D between the diaphragm AS and the reflection surface RP2 and the optical effective diameter CA of the light exit surface RP1 of the second mirror group LG2 and the maximum distance D between the diaphragm AS and the reflection surface RP2 The ratios of are all below an appropriate value, and this design method can reduce the volume of the projection lens PL.

In addition, since at least one of the light incident surface RP3, the reflection surface RP2 and the light exit surface RP1 of the second mirror group LG2 is a free-form surface, the second mirror group LG2 can also make the focal length of the image beam IMB corresponding to each viewing angle different, thereby improving the trapezoidal shape Distortion phenomenon. In this embodiment, the light incident surface RP3 , the reflection surface RP2 and the light output surface RP1 of the second mirror group LG2 may all be free-form curved surfaces, but the invention is not limited to this. In another embodiment, the light exit surface RP1 and the reflection surface RP2 of the second mirror group LG2 may be free curved surfaces, and the light incident surface RP3 may not be free curved surfaces. In yet another embodiment, the reflection surface RP2 and the light incident surface RP3 of the second mirror group LG2 may be free curved surfaces, and the light exit surface RP1 may not be free curved surfaces. In this embodiment, the focal length of the second lens group LG2 is, for example, a positive value.

In this embodiment, the image beam IMB has an offset value O relative to the first optical axis X1 of the first mirror group LG1. The method for measuring the offset O will be described below with reference to FIG. 3 .

FIG. 3 is a schematic diagram of a projection apparatus according to an embodiment of the present invention. 1 and 3, the projector PJT in FIG. 3 at least includes the illumination light source ILS, the light valve LV and the projection lens PL in FIG. 1, and the projector PJT is suitable for forming a projection image IM on the projection surface PS. Referring to FIG. 3 , in the method for measuring the offset O, first, the levelness of the projector PJT is corrected so that the first optical axis X1 of the projector PJT is level with the ground GD. Next, when the first optical axis X1 of the projector PJT is kept horizontal with the ground GD, the projector PJT is made to project a projection image IM on the projection surface PS. Then, measure the height h of the projection image IM, the distance a from an edge IMe of the projection image IM far from the ground GD to the ground GD, and the distance b from the first optical axis X1 of the projector PJT to the ground GD. Finally, using the following formula: O=[(a-b)/h]∙100%, the offset value O of the image beam IMB relative to the first optical axis X1 of the first mirror group LG1 is calculated. For example, in this embodiment, O may be greater than 50%, but the present invention is not limited thereto.

FIG. 4 schematically depicts a projection image formed by an image light beam on a projection surface according to an embodiment of the present invention. Please refer to FIG. 1 , FIG. 2 and FIG. 4 , in this embodiment, the light valve LV converts the illumination light beam ILB into an image light beam IMB, and the image light beam IMB sequentially passes through the first mirror group LG1 , passes through the aperture AS, passes through the The light incident surface RP3 of the second mirror group LG2 is reflected by the reflection surface RP2 of the second mirror group LG2, passes through the light exit surface RP1 of the second mirror group LG2, and forms a projection on the projection surface PS (ie, the paper surface of FIG. 4 ) Picture IM; the opposite sides IMa and IMb of the projection picture IM are parallel to each other and have lengths A and B respectively in a direction x, and the projection picture IM has a maximum width W in the direction x, [(B-A)/W]‧100 %=T, and |T|<1%. In short, in this embodiment, the keystone distortion of the projection image IM is less than 1%

An embodiment of the projection apparatus 100 will be described in the following content. It should be noted that the data listed in the following Tables 1 to 3 are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make appropriate parameters or settings after referring to the present invention. However, it should still fall within the scope of the present invention. [Table I] surface element type Radius of curvature (mm) Spacing (mm) Refractive Index (Nd) Abbe number (Vd) material RP1 The second mirror group LG2 freeform surface 31.844 4.988 1.535 55.8 RP2 freeform surface 10.596 -2.227 RP3 freeform surface -3.432 -5.179 ASa Aperture AS gigantic -0.571 L11 Lens L1 freeform surface 12.609 -3.509 1.653 22.4 plastic L12 Aspherical 4.992 -0.1 L21 Lens L2 spherical 118.405 -6.493 1.49 70.2 Glass L22 spherical 7.258 -0.1 L31 Lens L3 spherical 19.17 -1.1 1..858 24.1 Glass L41 Lens L4 spherical -5.713 -2.258 1.651 56.8 Glass L42 spherical -15.755 -0.1 L51 Lens L5 Aspherical -7.113 -4.982 1.535 55.8 plastic L52 Aspherical 8.962 -0.8 AC1 Flat Glass Actuator AC gigantic -2 1.526 58.6 Glass AC2 gigantic -0.8 PR1 Photosynthetic element PR gigantic -8.4 1.842 43 PR2 gigantic -1 CG1 Protective cover CG gigantic -1.1 1.151 61 Glass CG2 gigantic -0.303 LVa Light valve LV gigantic 0

Table 1 lists various parameters of the projection apparatus 100 according to an embodiment of the present invention. Please refer to FIG. 2 and Table 1. The spacing in Table 1 refers to the linear distance on the optical axis X between two adjacent surfaces. For example, the distance between the first surfaces L11 is the linear distance between the first surface L11 and the second surface L12 on the first optical axis X1. For the curvature radius, spacing, refractive index, Abbe number and material corresponding to each surface/component in Table 1, please refer to the values and contents corresponding to each curvature radius, spacing, refractive index, Abbe number and material in the same column. In addition, in Table 1, Rp1 is the light-emitting surface of the second mirror group LG2, Rp2 is the reflective surface of the second mirror group LG2, Rp3 is the light-incident surface of the second mirror group LG2, and L11 is the second mirror of the lens L1 facing toward the second mirror. The first surface of the group LG2, L12 is the second surface of the lens L1 facing the light valve LV, ASa is the light passage section of the aperture AS, L21 is the first surface of the lens L2 facing the second mirror group LG2, L22 is the lens The second surface of L2 facing the light valve LV, L31 is the first surface of the lens L3 facing the second mirror group LG2, L41 is the first surface of the lens L4 facing the second mirror group LG2, L42 is the first surface of the lens L4 facing the light The second surface of the valve LV, L51 is the first surface of the lens L5 facing the second mirror group LG2, L52 is the second surface of the lens L54 facing the light valve LV, AC1 is the plate glass actuator AC facing the second mirror The first surface of the group LG2, AC2 is the second surface of the plate glass actuator AC facing the light valve LV, PR1 is the first surface of the light combining element PR facing the second mirror group LG2, and PR2 is the light combining element PR. The second surface facing the light valve LV, CG1 is the first surface of the protective cover CG facing the second mirror group LG2, CG2 is the second surface of the protective cover CG facing the light valve LV, and the light receiving surface of the LVa light valve LV.

Referring to FIG. 2 and Table 1, in this embodiment, the lens L1 can be a free-form surface lens. Specifically, the first surface L11 of the lens L1 facing the second mirror group LG2 can be a free-form surface, and the second surface L12 of the lens L1 facing the light valve LV can be an aspherical surface. In this embodiment, the lens L2 can be a spherical lens. The first surface L21 of the lens L2 facing the second mirror group LG2 and the second surface L22 facing the light valve LV may both be spherical surfaces.

In this embodiment, the lens L3 can be a spherical lens. The first surface L31 of the lens L3 facing the second mirror group LG2 and the second surface L32 of the lens L3 facing the light valve LV may both be spherical surfaces. In this embodiment, the lens L4 can be a spherical lens. The first surface L41 of the lens L4 facing the second mirror group LG2 and the second surface L42 of the lens L4 facing the light valve LV may both be spherical surfaces. In addition, in the present embodiment, the second surface L32 of the lens L3 and the first surface L41 of the lens L4 can be bonded together, so that the lens L3 and the lens L4 form a double cemented lens.

In this embodiment, the lens L5 can be an aspherical lens. Specifically, the first surface L51 of the lens L5 facing the second mirror group LG2 and the second surface L52 facing the light valve LV may both be aspherical.

式中，Z為光軸X方向之偏移量（sag），c是密切球面（osculating sphere）之半徑的倒數，也就是接近光軸X處的曲率半徑（如表一內的曲率半徑）的倒數。k是二次曲面係數（conic），r是非球面高度，即為從透鏡中心往透鏡邊緣的高度，而A ₂、A ₄、A ₆、A ₈、…為非球面係數（aspheric coefficient）。表二列出透鏡L1的第二表面L12、透鏡L5的第一表面L51及透鏡L5的第二表面L52的二次曲面係數及各非球面係數。 [表二] 表面 L12 L51 L52 二次曲面係數k 0.133 -2.846 0.381 係數A ⁴ 4.81550E-04 2.31310E-05 -1.50680E-04 係數A ⁶ -3.84030E-07 2.99620E-06 4.90730E-07 係數A ⁸   -8.60850E-09 2.97760E-08 The above-mentioned second surface L12 of the lens L1, the first surface L51 of the lens L5, and the second surface L52 of the lens L5 are even-order aspheric surfaces, and the even-order aspheric surfaces can be expressed by the following formula:

In the formula, Z is the offset in the X direction of the optical axis (sag), and c is the reciprocal of the radius of the osculating sphere, that is, the radius of curvature close to the optical axis X (such as the radius of curvature in Table 1). reciprocal. k is a quadratic surface coefficient (conic), r is the height of the aspheric surface, that is, the height from the center of the lens to the edge of the lens, and A ₂ , A ₄ , A ₆ , A ₈ , . . . are aspheric coefficients. Table 2 lists quadric coefficients and respective aspheric coefficients of the second surface L12 of the lens L1, the first surface L51 of the lens L5, and the second surface L52 of the lens L5. [Table II] surface L12 L51 L52 Quadratic coefficient k 0.133 -2.846 0.381 Coefficient A ⁴ 4.81550E-04 2.31310E-05 -1.50680E-04 Coefficient A ⁶ -3.84030E-07 2.99620E-06 4.90730E-07 Coefficient A ⁸ -8.60850E-09 2.97760E-08

式中，Z為光學面深度，r為曲率半徑，k是圓錐常數（conic constant），Φ是透鏡口徑，C _mn,為xy多項式的係數。由表一中的曲率半徑、表三中的x ^my ⁿ多項式的係數及上述對應的展開式可建立對應的自由曲面。 [表三] x ^my ⁿ多項式係數 RP1 RP2 RP3 L11 y的多項式係數 3.73960E-01 4.56960E-02 -4.65100E-01 -4.85000E-02 x ²的多項式係數 -4.32410E-02 -4.31610E-02 5.70580E-02 1.46790E-02 y ²的多項式係數 -9.75230E-02 -4.53500E-02 5.66030E-02 1.29000E-02 x ²y的多項式係數 -7.04390E-04 -1.19130E-04 -1.16570E-02 -2.55610E-03 y ³的多項式係數 1.06880E-02 8.07920E-04 -1.31230E-02 -2.83740E-03 x ⁴的多項式係數 1.21800E-03 -4.48560E-05 1.46620E-04 3.44080E-03 x ²y ²的多項式係數 2.68250E-03 -6.48470E-05 1.59640E-03 6.88920E-03 y ⁴的多項式係數 5.45350E-04 -1.81930E-04 -1.76290E-04 3.45130E-03 x ⁴y的多項式係數 -5.36970E-05 -3.41710E-06 -5.66890E-04 -2.03770E-04 x ²y ³的多項式係數 -2.47210E-04 1.01700E-04 -8.99270E-04 -4.59070E-04 y ⁵的多項式係數 -2.05140E-04 2.57940E-06 -3.32560E-04 -2.27020E-04 x ⁶的多項式係數 -3.20420E-05 -1.60010E-05 3.44260E-05 1.95360E-04 x ⁴y ²的多項式係數 -7.08860E-05 -2.84000E-05 -2.30490E-04 5.62460E-04 x ²y ⁴的多項式係數 -1.48630E-05 -8.81300E-05 -1.12350E-03 5.47330E-04 y ⁶的多項式係數 1.90740E-05 -8.43360E-06 -5.09320E-04 1.73550E-04 x ⁶y的多項式係數 5.30600E-06 8.41480E-06 8.61970E-05 1.70500E-05 x ⁴y ³的多項式係數 1.05270E-05 -1.73400E-06 2.33610E-06 3.15430E-05 x ²y ⁵的多項式係數 4.85560E-08 1.84170E-05 6.86320E-05 5.86140E-05 y ⁷的多項式係數 -7.55950E-07 1.76990E-06 -1.64650E-04 1.54730E-05 x ⁸的多項式係數 4.66660E-07 8.12190E-07 5.57060E-06 -4.12740E-06 x ⁶y ²的多項式係數 6.93520E-07 8.34820E-07 7.47250E-05 -1.60850E-05 x ⁴y ⁴的多項式係數 -7.36010E-08 5.02340E-06 2.20920E-04 -2.82570E-06 x ²y ⁶的多項式係數 3.24650E-07 1.32680E-07 3.26260E-04 -5.32250E-06 y ⁸的多項式係數 8.69560E-09 1.68230E-07 2.06690E-04 1.23870E-06 x ⁸y的多項式係數 -9.23210E-08 -5.82240E-07 -1.16650E-05 -6.99950E-06 x ⁶y ³的多項式係數 -1.12780E-07 -5.98200E-07 -4.10250E-05 -1.68450E-05 x ⁴y ⁵的多項式係數 -4.50550E-08 -1.20390E-06 -1.97560E-05 -3.08280E-05 x ²y ⁷的多項式係數 5.45590E-08 -4.34210E-07 1.33260E-06 -2.25730E-05 y ⁹的係數 -3.93740E-09 -5.41920E-08 4.13600E-05 -4.93650E-06 x ¹⁰的係數 -4.46580E-10 4.26590-E09 1.55260E-06 1.42660E-06 x ⁸y ²的係數 -6.30810E-11 7.55270E-08 -1.35870E-06 8.27570E-06 x ⁶y ⁴的係數 2.68880E-09 5.00410E-08 -4.04550E-06 1.04590E-05 x ⁴y ⁶的係數 3.74200E-10 8.73540E-08 -3.37610E-05 1.24310E-05 x ²y ⁸的係數 -7.57250E-09 3.41710E-08 -4.32090E-05 6.61670E-06 y ¹⁰的係數 1.14070E-09 2.49110E-09 -3.08130E-05 1.18280E-06 Referring to FIG. 2 and Table 1, in this embodiment, the light exit surface RP1 of the second mirror group LG2, the reflection surface RP2 of the second mirror group LG2, the light incident surface RP3 of the second mirror group LG2, and the first mirror of the lens L1 The surface L11 is a free-form surface, and the free-form surface can be expressed by the following formula:

where Z is the depth of the optical surface, r is the radius of curvature, k is the conic constant, Φ is the aperture of the lens, and C _mn is the coefficient of the xy polynomial. The corresponding free-form surface can be established from the curvature radius in Table 1, the coefficients of the x ^m y ⁿ polynomial in Table 3, and the above-mentioned corresponding expansion. [Table 3] x ^m y ⁿ polynomial coefficients RP1 RP2 RP3 L11 polynomial coefficients of y 3.73960E-01 4.56960E-02 -4.65100E-01 -4.85000E-02 Polynomial coefficients of x ² -4.32410E-02 -4.31610E-02 5.70580E-02 1.46790E-02 Polynomial coefficients of y ² -9.75230E-02 -4.53500E-02 5.66030E-02 1.29000E-02 Polynomial coefficients of x ² y -7.04390E-04 -1.19130E-04 -1.16570E-02 -2.55610E-03 Polynomial coefficients of y ³ 1.06880E-02 8.07920E-04 -1.31230E-02 -2.83740E-03 Polynomial coefficients of x ⁴ 1.21800E-03 -4.48560E-05 1.46620E-04 3.44080E-03 Polynomial coefficients of x ² y ² 2.68250E-03 -6.48470E-05 1.59640E-03 6.88920E-03 Polynomial coefficients of y ⁴ 5.45350E-04 -1.81930E-04 -1.76290E-04 3.45130E-03 Polynomial coefficients of x ⁴ y -5.36970E-05 -3.41710E-06 -5.66890E-04 -2.03770E-04 Polynomial coefficients of x ² y ³ -2.47210E-04 1.01700E-04 -8.99270E-04 -4.59070E-04 Polynomial coefficients of y ⁵ -2.05140E-04 2.57940E-06 -3.32560E-04 -2.27020E-04 Polynomial coefficients of x ⁶ -3.20420E-05 -1.60010E-05 3.44260E-05 1.95360E-04 Polynomial coefficients of x ⁴ y ² -7.08860E-05 -2.84000E-05 -2.30490E-04 5.62460E-04 Polynomial coefficients of x ² y ⁴ -1.48630E-05 -8.81300E-05 -1.12350E-03 5.47330E-04 Polynomial coefficients of y ⁶ 1.90740E-05 -8.43360E-06 -5.09320E-04 1.73550E-04 Polynomial coefficients of x ⁶ y 5.30600E-06 8.41480E-06 8.61970E-05 1.70500E-05 Polynomial coefficients of x ⁴ y ³ 1.05270E-05 -1.73400E-06 2.33610E-06 3.15430E-05 Polynomial coefficients of x ² y ⁵ 4.85560E-08 1.84170E-05 6.86320E-05 5.86140E-05 Polynomial coefficient of y ⁷ -7.55950E-07 1.76990E-06 -1.64650E-04 1.54730E-05 Polynomial coefficients of x ⁸ 4.66660E-07 8.12190E-07 5.57060E-06 -4.12740E-06 Polynomial coefficients of x ⁶ y ² 6.93520E-07 8.34820E-07 7.47250E-05 -1.60850E-05 Polynomial coefficients of x ⁴ y ⁴ -7.36010E-08 5.02340E-06 2.20920E-04 -2.82570E-06 Polynomial coefficients of x ² y ⁶ 3.24650E-07 1.32680E-07 3.26260E-04 -5.32250E-06 Polynomial coefficients of y ⁸ 8.69560E-09 1.68230E-07 2.06690E-04 1.23870E-06 Polynomial coefficients of x ⁸ y -9.23210E-08 -5.82240E-07 -1.16650E-05 -6.99950E-06 Polynomial coefficients of x ⁶ y ³ -1.12780E-07 -5.98200E-07 -4.10250E-05 -1.68450E-05 Polynomial coefficients of x ⁴ y ⁵ -4.50550E-08 -1.20390E-06 -1.97560E-05 -3.08280E-05 Polynomial coefficients of x ² y ⁷ 5.45590E-08 -4.34210E-07 1.33260E-06 -2.25730E-05 Coefficient of y ⁹ -3.93740E-09 -5.41920E-08 4.13600E-05 -4.93650E-06 factor of x ¹⁰ -4.46580E-10 4.26590-E09 1.55260E-06 1.42660E-06 Coefficient of x ⁸ y ² -6.30810E-11 7.55270E-08 -1.35870E-06 8.27570E-06 Coefficient of x ⁶ y ⁴ 2.68880E-09 5.00410E-08 -4.04550E-06 1.04590E-05 Coefficient of x ⁴ y ⁶ 3.74200E-10 8.73540E-08 -3.37610E-05 1.24310E-05 Coefficient of x ² y ⁸ -7.57250E-09 3.41710E-08 -4.32090E-05 6.61670E-06 Coefficient of y ¹⁰ 1.14070E-09 2.49110E-09 -3.08130E-05 1.18280E-06

In this embodiment, the projection lens PL has a large half angle of view; that is, the projection lens PL has a small throw ratio and can project a wide projection image within a short projection distance. For example, in this embodiment, the half angle of view of the projection lens PL may be greater than 45 ^° , but the present invention is not limited to this.

FIG. 5 is a modulation transfer function diagram of the projection lens of FIG. 2 . The Modulation Transfer Function (MTF) diagram of FIG. 5 can be used to evaluate the performance of the projection lens PL, and the graphs shown in FIG. 5 are all within the standard range. Therefore, it can be verified that the projection lens PL of this embodiment can achieve a good imaging effect.

FIG. 6 schematically depicts a projection image on a projection surface of the projection apparatus of FIG. 1 . The shape of the projection screen IM shown in FIG. 6 is close to a rectangle. It can be verified from FIG. 6 that the projection device 100 can indeed utilize the asymmetric free-form surface of the optical element of the projection lens PL (for example, at least one of the light-emitting surface RP1 , the reflecting surface RP2 and the light-incident surface RP3 of the second mirror group LG2 ) Effectively improve keystone distortion.

To sum up, the projection device and the projection lens according to an embodiment of the present invention include a first mirror group disposed between the reduction side and the enlargement side, a second mirror group disposed between the first mirror group and the enlargement side, and A diaphragm between the first mirror group and the second mirror group. The second mirror group has a light incident surface, a reflective surface and a light emitting surface, the light incident surface faces the first mirror group, the light emitting surface faces the projection surface, and the light incident surface, the light emitting surface and the first mirror group are arranged on the same side of the reflective surface. The light valve is adapted to provide the image beam. The image beam sequentially passes through the first mirror group, passes through the aperture, passes through the light incident surface of the second mirror group, is reflected by the reflective surface of the second mirror group, and passes through the light exit surface of the second mirror group to be transmitted to the projection. noodle. In particular, at least one of the light incident surface, the reflection surface and the light output surface of the second mirror group is a free-form surface, and the first optical axis of the first mirror group does not overlap the center of the image beam. Thereby, the projection lens can have a common optical path design. Since the projection lens has a common optical path design, the image beam reflected by the reflection surface of the second mirror group back to the first mirror group is less likely to cause interference, and the distance between the diaphragm and the reflection surface of the second mirror group can be shortened. When the distance between the diaphragm and the reflection surface of the second mirror group is shortened, the optical effective diameter of the reflection surface of the second mirror group will not be too large. In this way, the overall thickness and volume of the projection lens can be effectively reduced.

However, the above are only preferred embodiments of the present invention, and should not limit the scope of the present invention, that is, any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the description of the invention, All still fall within the scope of the patent of the present invention. In addition, it is not necessary for any embodiment of the present invention or the claimed scope of the present invention to achieve all of the objects or advantages or features disclosed in the present invention. In addition, the abstract section and the title are only used to aid the search of patent documents and are not intended to limit the scope of the present invention. In addition, terms such as "first" and "second" mentioned in this specification or the scope of the patent application are only used to name the elements or to distinguish different embodiments or scopes, and are not used to limit the number of elements. upper or lower limit.

100: Projection Device A, B: length a, b: distance AC1, CG1, L11, L21, L31, L41, L51, PR1: first surface AC2, CG2, L12, L22, L32, L42, L52, PR2: Second surface AC: Flat Glass Actuator AS: Aperture Asa: clear light cross section CG: Protective cover CA: optical effective diameter D: maximum distance GD: Ground H: Thickness h: height H1, H2: maximum distance IM: Projection screen IMa, IMb: edge IMe: The Edge IMB: Image Beam IMB1: First edge ray IMB2: Second Edge Ray IMBc: Center ILB: Lighting Beam ILS: Lighting System LG1: The first mirror group LG2: The second mirror group LV: light valve LVa: light-receiving surface LVe: edge LVp: point L1, L2, L3, L4, L5: Lenses PJT: Projector PL: Projection Lens PR: Combined light element PS: Projection surface RP: The turning point RP1: light-emitting surface RP2: Reflective Surface RP3: light incident surface W: maximum width X1: The first optical axis x, y, z, d1, d2: direction θ: included angle.

FIG. 1 is a schematic side view of a projection apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged schematic view of a light valve, a protective cover, a light combining element, a plate glass actuator and a projection lens of the projection apparatus of FIG. 1 . FIG. 3 is a schematic diagram of a projection apparatus according to an embodiment of the present invention. FIG. 4 schematically depicts a projection image formed by an image light beam on a projection surface according to an embodiment of the present invention. FIG. 5 is a modulation transfer function diagram of the projection lens of FIG. 2 . FIG. 6 schematically depicts a projection image on a projection surface of the projection apparatus of FIG. 1 .

AC1, CG1, L11, L21, L31, L41, L51, PR1: first surface

AC2, CG2, L12, L22, L32, L42, L52, PR2: Second surface

AC: Flat Glass Actuator

AS: Aperture

Asa: clear light cross section

CG: Protective cover

CA: optical effective diameter

D: maximum distance

H: Thickness

H1, H2: maximum distance

IMB: Image Beam

IMB1: First edge ray

IMB2: Second Edge Ray

IMBc: Center

LG1: The first mirror group

LG2: The second mirror group

LV: light valve

LVa: light-receiving surface

LVe: edge

LVp: point

L1, L2, L3, L4, L5: Lenses

PL: Projection Lens

PR: Combined light element

RP: The turning point

RP1: light-emitting surface

RP2: Reflective Surface

RP3: light incident surface

X1: The first optical axis

x, y, z, d1, d2: direction

Claims (14)

A projection lens, suitable for imaging a light valve arranged on a reduction side on a projection surface arranged on the enlargement side, the light valve and the projection surface have an angle, the projection lens comprising: a first lens group, disposed between the reduction side and the enlargement side, and having a first optical axis; A second mirror group is disposed between the first mirror group and the magnifying side, wherein the second mirror group at least has a light incident surface, a reflection surface and a light emitting surface, and the light incident surface faces the first mirror The light emitting surface faces the projection surface, the light incident surface, the light emitting surface and the first mirror group are arranged on the same side of the reflective surface, and at least one of the light incident surface, the reflective surface and the light emitting surface is a freeform surface; and A diaphragm is disposed between the first mirror group and the second mirror group, wherein the light valve is suitable for providing an image beam, and the image beam sequentially passes through the first mirror group, through the diaphragm, and through the pass through the light incident surface of the second mirror group, be reflected by the reflection surface of the second mirror group, and pass through the light exit surface of the second mirror group to be transmitted to the projection surface, and the first mirror group The first optical axis does not overlap the center of the image beam. The projection lens as claimed in claim 1, wherein the second mirror group comprises a turning horn, and the turning horn has the light incident surface, the reflection surface and the light emitting surface. The projection lens of claim 1, wherein the first lens group comprises a plurality of lenses arranged in sequence from the magnification side to the reduction side, each of the lenses has a first lens group facing the second lens group A surface and a second surface facing the light valve, and the first surface of the lenses closest to the diaphragm is a free-form surface. The projection lens of claim 1, wherein the diaphragm and the reflection surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, and the image beam includes a first edge ray and a second edge ray, the first edge ray exits from a point on an edge of the light valve in a direction away from the first optical axis, and the second edge ray exits from the point on the edge of the light valve toward the direction of the first optical axis The light is emitted in the direction of the first optical axis, and the first edge light in the first lens group and the first optical axis have a maximum distance H1 in a direction perpendicular to the first optical axis. The second edge light on the light-emitting surface of the mirror group and the first optical axis have a maximum distance H2 in the direction perpendicular to the first optical axis, and (H1+H2)/D<3. The projection lens of claim 1, wherein the diaphragm and the reflection surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, and the light emitting surface of the second mirror group has a maximum distance D. It has an optical effective diameter CA, and CA/D<3. The projection lens of claim 1, wherein the image beam has an offset value relative to the first optical axis of the first lens group. The projection lens of claim 1, wherein the angle is θ, and 25 ^o <θ < 90 ^o . The projection lens according to claim 1, wherein the image beam forms a projection picture on the projection surface, opposite sides of the projection picture are parallel to each other and have a length A and a length B respectively in one direction, and the projection picture is in the There is a maximum width W in this direction, [(B-A)/W]·100%=T, and |T|<1%. A projection device, comprising: an illumination light source, adapted to provide an illumination beam; a light valve, disposed on a reduction side and adapted to convert the illumination beam into an image beam; a projection surface disposed on an enlarged side, wherein the light valve and the projection surface have an angle; and A projection lens, including: a first lens group, disposed between the reduction side and the enlargement side, and having a first optical axis; A second mirror group is disposed between the first mirror group and the magnifying side, wherein the second mirror group at least has a light incident surface, a reflection surface and a light emitting surface, and the light incident surface faces the first mirror The light emitting surface faces the projection surface, the light incident surface, the light emitting surface and the first mirror group are arranged on the same side of the reflective surface, and at least one of the light incident surface, the reflective surface and the light emitting surface is a freeform surface; and A diaphragm is disposed between the first mirror group and the second mirror group, wherein the image beam sequentially passes through the first mirror group, passes through the diaphragm, and passes through the incident light of the second mirror group surface, is reflected by the reflecting surface of the second mirror group and passes through the light emitting surface of the second mirror group to be transmitted to the projection surface, and the first optical axis of the first mirror group does not overlap with the image beam center of. The projection device as claimed in claim 9, wherein the second mirror group comprises a turning point, and the turning point has the light incident surface, the reflection surface and the light emitting surface. The projection device of claim 9, wherein the first lens group comprises a plurality of lenses arranged in sequence from the magnification side to the reduction side, each of the lenses has a first lens group facing the second lens group A surface and a second surface facing the light valve, and the first surface of the lenses closest to the diaphragm is a free-form surface. The projection device according to claim 9, wherein the diaphragm and the reflection surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, and the image beam includes a first edge ray and a second edge ray, the first edge ray exits from a point on an edge of the light valve in a direction away from the first optical axis, and the second edge ray exits from the point on the edge of the light valve toward the direction of the first optical axis The light is emitted in the direction of the first optical axis, and the first edge light in the first lens group and the first optical axis have a maximum distance H1 in a direction perpendicular to the first optical axis. The second edge light on the light-emitting surface of the mirror group and the first optical axis have a maximum distance H2 in the direction perpendicular to the first optical axis, and (H1+H2)/D<3. The projection device according to claim 9, wherein the diaphragm and the reflection surface of the second mirror group have a maximum distance D in a direction parallel to the first optical axis, and the light emitting surface of the second mirror group has a maximum distance D. It has an optical effective diameter CA, and CA/D<3. The projection device of claim 9, wherein the image beam has an offset value relative to the first optical axis of the first lens group.

Images