CN114460721A

CN114460721A - Projection lens, projection device, electronic apparatus, and vehicle

Info

Publication number: CN114460721A
Application number: CN202210183697.5A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shanghai Ofilm Intelligent Vehicle Co ltd
Current assignee: Shanghai Ofilm Intelligent Vehicle Co ltd
Priority date: 2022-02-25
Filing date: 2022-02-25
Publication date: 2022-05-10

Abstract

The invention discloses a projection lens, a projection device, an electronic device and a vehicle, wherein the projection lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from an object side to an image side along an optical axis, the first lens has negative focal power, the object side surface of the first lens is a convex surface at a position close to the optical axis, the image side surface of the first lens is a concave surface at a position close to the optical axis, and the first lens is an aspheric lens; the second lens has positive focal power; the third lens has positive focal power; the fourth lens has negative focal power; the fifth lens has negative focal power; the sixth lens has positive focal power, and the fifth lens and the sixth lens are cemented to form a cemented lens with negative focal power; the seventh lens element has positive refractive power, and has a convex object-side surface and a convex image-side surface at paraxial regions. The projection lens can realize short-distance projection imaging while ensuring the quality of projection imaging.

Description

Projection lens, projection device, electronic apparatus, and vehicle

Technical Field

The invention relates to the technical field of optical imaging, in particular to a projection lens, a projection device, electronic equipment and a vehicle.

Background

The projection equipment at present is mostly used for cinema or advertisement projection, and the projection distance of the projection equipment, namely the distance between the projection equipment and a projection imaging surface, generally needs to reach more than 1 meter, and has higher requirement on space. However, in real life, there are situations that it is necessary to realize short-distance projection imaging, for example, a head-up display device mounted inside a vehicle is limited by a space inside the vehicle, and a projection distance needs to be controlled within a small range.

Disclosure of Invention

The embodiment of the invention discloses a projection lens, a projection device, electronic equipment and a vehicle, which can realize short-distance projection imaging and ensure the quality of projection imaging.

In order to achieve the above object, a first aspect of the present invention discloses a projection lens including, in order from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens:

the first lens element has a negative focal power, an object-side surface of the first lens element is convex at a paraxial region, an image-side surface of the first lens element is concave at a paraxial region, and the first lens element is an aspheric lens element;

the second lens has positive optical power;

the third lens has positive optical power;

the fourth lens has a negative optical power;

the fifth lens has a negative optical power;

the sixth lens has positive focal power, and the fifth lens and the sixth lens are cemented to form a cemented lens with negative focal power;

the seventh lens element has positive optical power, the object-side surface of the seventh lens element is convex at a paraxial region, the image-side surface of the seventh lens element is convex at a paraxial region, and the seventh lens element is an aspheric lens element;

the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all glass lenses.

The projection lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are made of glass materials, so that the temperature resistance and the imaging stability of the projection lens are guaranteed, on the basis, the first lens has negative focal power, and the object side surface and the image side surface of the first lens are respectively a convex surface and a concave surface at the positions close to an optical axis, so that light is favorably diffused, the projection lens obtains a large field angle, the projection ratio is reduced, the incidence angle of light at the image side when the light enters each lens is favorably reduced, the coma aberration, curvature of field and other aberrations of the projection lens are balanced, and meanwhile, the first lens is an aspheric lens, so that the distortion is favorably eliminated; the cemented lens with negative focal power formed by the fifth lens and the sixth lens is beneficial to eliminating chromatic aberration of the projection lens and improving the projection imaging quality, and no air gap exists between the fifth lens and the sixth lens, so that the projection lens is more compact and simpler in structure; and the seventh lens is an aspheric lens with positive focal power, so that the aberration of the projection lens can be eliminated, and the external aberration such as astigmatism and coma can be corrected.

As an optional implementation manner, in an embodiment of the first aspect of the present invention, the projection lens satisfies the following relation: -3. ltoreq. f 1/f.ltoreq.0.5, 0. ltoreq. f 2/f.ltoreq.1.5, 0.5. ltoreq. f 3/f.ltoreq.2.5, -4. ltoreq. f 4/f.ltoreq.1.5, -2. ltoreq. f 5/f.ltoreq.0, 0.5. ltoreq. f 6/f.ltoreq.3.5 and 0.2. ltoreq. f 7/f.ltoreq.3.5;

wherein f is an effective focal length of the projection lens, f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens, f4 is a focal length of the fourth lens, f5 is a focal length of the fifth lens, f6 is a focal length of the sixth lens, and f7 is a focal length of the seventh lens. When the focal powers of the first lens and the seventh lens are too large, the eccentric inclination sensitivity of the first lens and the seventh lens is caused, and when the focal powers of the second lens to the sixth lens are too small, the second lens to the sixth lens cannot perform the function of correcting the primary aberration of the projection lens, and the waste of the lenses is caused. Therefore, in the embodiment, the ratio of the focal lengths of the first lens to the seventh lens of the projection lens to the focal length of the projection lens is limited to reasonably control the focal lengths of the lenses of the projection lens, so as to correct the primary aberration of the projection lens, balance the primary aberration and the high-order aberration, improve the optical performance of the projection lens, and simultaneously, avoid the lens sensitivity caused by too large focal length of each lens or the waste of the lens surface shape caused by too small focal length of each lens.

As an alternative implementation manner, in an embodiment of the first aspect of the present invention, the object-side surface of the second lens element is convex at a paraxial region, and the image-side surface of the second lens element is convex at a paraxial region. The object side surface and the image side surface of the second lens are convex surfaces and are combined with the first lens with negative focal power, so that field curvature of the projection lens can be eliminated, and the projection imaging quality of the projection lens is improved.

As an alternative implementation, in an embodiment of the first aspect of the invention, the third lens and the fourth lens are cemented to form a cemented lens with negative optical power. Through with third lens and fourth lens veneer, be favorable to further eliminating projection lens's colour difference, improve the projection imaging quality, be favorable to making projection lens's structure compacter simple simultaneously.

As an optional implementation manner, in an embodiment of the first aspect of the present invention, the projection lens further includes a diaphragm, and the diaphragm is located between the fourth lens and the fifth lens. The diaphragm is arranged between the fourth lens and the fifth lens, so that the projection lens is in a symmetrical structure, the aberration of the projection lens, such as coma aberration, distortion, vertical axis chromatic aberration and the like, can be weakened, and the projection imaging quality can be improved.

In a second aspect, the present invention discloses a projection apparatus, which includes a light valve and the projection lens according to the first aspect, wherein the light valve is disposed on an image side of the projection lens, and the light valve is configured to generate an image beam and emit the image beam to the projection lens. The projection device with the projection lens can ensure the quality of projection imaging while realizing short-distance projection imaging.

As an optional implementation manner, in an embodiment of the second aspect of the present invention, the projection apparatus further includes a prism, the prism is located between the light valve and the projection lens, the prism is configured to reflect the illumination beam to the light valve, so that the light valve generates the image beam, and the prism is further configured to emit the image beam to the projection lens. Through setting up the prism, can reflect illumination beam to the light valve and produce the image beam to realize projection imaging.

As an optional implementation manner, in an embodiment of the second aspect of the present invention, the projection apparatus further includes a protective glass, and the protective glass is disposed on a side of the light valve facing the prism. Because the protective glass has high light transmittance and high intensity, the protective glass is arranged on one side of the light valve facing the prism, so that the light valve can be protected from the influence of the external environment while the normal use of the light valve is not influenced.

In a third aspect, the invention discloses an electronic device, which includes a housing and the projection apparatus as described in the second aspect, wherein the projection apparatus is disposed on the housing. The electronic equipment with the projection device can ensure the quality of projection imaging while realizing short-distance projection imaging.

In a fourth aspect, the invention discloses a vehicle, which comprises a vehicle body and the electronic device of the third aspect, wherein the electronic device is arranged on the vehicle body. The vehicle with the electronic equipment can realize the short-distance projection imaging with high projection imaging quality in the limited space of the vehicle.

Compared with the prior art, the invention has the beneficial effects that: according to the projection lens, the projection device, the electronic equipment and the vehicle provided by the embodiment of the invention, the projection lens adopts seven glass lenses to ensure the temperature resistance and the imaging stability of the projection lens, the first lens with negative focal power is utilized to increase the light emergence angle and reduce the projection ratio of the electronic equipment, so that the focal power and the surface shape of each lens are reasonably configured while a large-size image is projected at a position close to the electronic equipment, the first lens and the seventh lens with aspheric object side surfaces and image side surfaces are selected, and the fifth lens and the sixth lens are glued to form the cemented lens, so that the aberration of the projection lens is eliminated, and the projection at a close distance has good imaging quality.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a projection lens disclosed in a first embodiment of the present application;

FIG. 2 is a graph of a modulation transfer function of a projection lens disclosed in a first embodiment of the present application;

fig. 3 is a light ray dot arrangement diagram of a projection lens disclosed in the first embodiment of the present application;

fig. 4 is a field curvature diagram of a projection lens disclosed in the first embodiment of the present application;

fig. 5 is a distortion diagram of a projection lens disclosed in the first embodiment of the present application;

fig. 6 is a vertical axis chromatic aberration diagram of a projection lens disclosed in the first embodiment of the present application;

fig. 7 is a schematic structural diagram of a projection lens disclosed in a second embodiment of the present application;

FIG. 8 is a graph of a modulation transfer function of a projection lens disclosed in a second embodiment of the present application;

fig. 9 is a light ray dot arrangement diagram of a projection lens disclosed in a second embodiment of the present application;

fig. 10 is a field curvature diagram of a projection lens disclosed in a second embodiment of the present application;

fig. 11 is a distortion diagram of a projection lens disclosed in the second embodiment of the present application;

fig. 12 is a vertical axis chromatic aberration diagram of a projection lens disclosed in the second embodiment of the present application;

FIG. 13 is a schematic diagram of a projection apparatus according to the present disclosure;

FIG. 14 is a schematic structural diagram of an electronic device disclosed herein;

fig. 15 is a schematic structural diagram of a vehicle disclosed herein.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the present invention, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "center", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are used primarily to better describe the invention and its embodiments and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meanings of these terms in the present invention can be understood by those skilled in the art as appropriate.

Furthermore, the terms "mounted," "disposed," "provided," "connected," and "connected" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.

Furthermore, the terms "first," "second," and the like, are used primarily to distinguish one device, element, or component from another (the specific nature and configuration may be the same or different), and are not used to indicate or imply the relative importance or number of the indicated devices, elements, or components. "plurality" means two or more unless otherwise specified.

The technical solution of the present invention will be further described with reference to the following embodiments and the accompanying drawings.

Referring to fig. 1, according to a first aspect of the present application, the present application discloses a projection lens 100, where the projection lens 100 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7, which are disposed in order from an object side to an image side along an optical axis O. During projection, the image beam sequentially enters the seventh lens L7, the sixth lens L6, the fifth lens L5, the fourth lens L4, the third lens L3, the second lens L2, the second lens L2 and the first lens L1 from the image side of the seventh lens L7, and is emitted to the imaging component on the object side to realize projection imaging. The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all glass lenses, the first lens L1 has negative focal power, the second lens L2 has positive focal power, the third lens L3 has positive focal power, the fourth lens L4 has negative focal power, the fifth lens L5 has negative focal power, the sixth lens L6 has positive focal power, and the seventh lens L7 has positive focal power. The object-side surface S1 of the first lens element L1 is convex at the paraxial region O, the image-side surface S2 of the first lens element L1 is concave at the paraxial region O, the object-side surface S13 of the seventh lens element L7 is convex at the paraxial region O, and the image-side surface S14 of the seventh lens element L7 is convex at the paraxial region O.

When the projection lens 100 is applied to a projection device of a vehicle, the imaging component may be a windshield of the vehicle.

Further, the first lens L1 and the seventh lens L7 are both aspherical lenses. That is, the object-side surface S1 and the image-side surface S2 of the first lens element L1 are aspheric, and the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are aspheric. The object-side surface and the image-side surface of the second lens element L2 through the fifth lens element L5 may be aspheric or spherical.

Further, the fifth lens L5 is cemented with the sixth lens L6 to form a cemented lens having a negative power.

The application provides a projection lens 100 is through the first lens L1 to the seventh lens L7 who chooses the glass material for use, can reduce the high temperature that comes from light source department that projection lens 100 received and influence, guarantees projection lens 100's temperature toleration and imaging stability, is favorable to improving projection imaging quality. On this basis, the first lens L1 of the projection lens 100 has negative focal power, and the object-side surface S1 and the image-side surface S2 of the first lens L1 are respectively a convex surface and a concave surface at a position close to the optical axis O, which is favorable for diffusing light rays, so that the projection lens 100 obtains a large field angle, reduces a projection ratio, and is also favorable for reducing an incident angle when light rays at the image side enter the image side of each lens, thereby balancing aberrations such as coma aberration and curvature of field of the projection lens 100, and meanwhile, the first lens L1 is an aspheric lens, which is favorable for eliminating distortion; the cemented lens with negative focal power formed by the cemented fifth lens L5 and the cemented sixth lens L6 is beneficial to eliminating chromatic aberration of the projection lens 100 and improving the projection imaging quality, and no air gap exists between the fifth lens L5 and the sixth lens L6, so that the projection lens 100 is more compact and simpler in structure; and the seventh lens L7 is an aspheric lens with positive focal power, which is beneficial to eliminating the aberration of the projection lens 100 and correcting the external aberration such as distortion and coma.

In some embodiments, projection lens 100 satisfies the relationship: -3. ltoreq. f 1/f.ltoreq.0.5, 0. ltoreq. f 2/f.ltoreq.1.5, 0.5. ltoreq. f 3/f.ltoreq.2.5, -4. ltoreq. f 4/f.ltoreq.1.5, -2. ltoreq. f 5/f.ltoreq.0, 0.5. ltoreq. f 6/f.ltoreq.3.5 and 0.2. ltoreq. f 7/f.ltoreq.3.5;

where f is an effective focal length of the projection lens 100, f1 is a focal length of the first lens L1, f2 is a focal length of the second lens L1, f3 is a focal length of the third lens L1, f4 is a focal length of the fourth lens L1, f5 is a focal length of the fifth lens L1, f6 is a focal length of the sixth lens L1, and f7 is a focal length of the seventh lens L1. When the optical powers of the first lens L1 and the seventh lens L7 are too large, the decentering tilt sensitivity of the first lens L1 and the seventh lens L7 is caused, and when the optical powers of the second lens L2 to the sixth lens L6 are too small, the waste of lenses is caused at the same time. Therefore, in the present embodiment, the ratio of the focal lengths of the first lens L1 to the seventh lens L7 of the projection lens 100 to the focal length of the projection lens 100 is defined to reasonably control the focal power of each lens of the projection lens 100, so as to correct the primary aberration of the projection lens 100, to balance the primary aberration and the high-order aberration, and to improve the optical performance of the projection lens 100, and at the same time, to avoid the lens sensitivity of each lens due to too large focal power or the waste of the lens surface shape of each lens due to too small focal power.

In some embodiments, the object-side surface S3 of the second lens element L2 is convex at the paraxial region O, and the image-side surface S4 of the second lens element L2 is convex at the paraxial region O. By providing the object side surface S3 and the image side surface S4 of the second lens L2 as convex surfaces and combining the second lens L1 having negative refractive power, curvature of field of the projection lens 100 can be eliminated, and the projection imaging quality of the projection lens 100 can be improved.

In some embodiments, the third lens L3 and the fourth lens L4 are cemented to form a cemented lens with negative optical power. The third lens L3 and the fourth lens L4 are glued, so that chromatic aberration of the projection lens 100 can be further eliminated, the projection imaging quality can be improved, and the structure of the projection lens 100 can be more compact and simpler.

In some embodiments, the projection lens 100 further includes a stop 101, and the stop 101 is located between the fourth lens L4 and the fifth lens L5. By arranging the diaphragm 101 between the fourth lens L4 and the fifth lens L5, the projection lens 100 has a symmetrical structure, which is beneficial to weakening aberrations of the projection lens 100, such as coma, distortion, vertical axis chromatic aberration, and the like, and improving the projection imaging quality. It is understood that the diaphragm 101 may be an aperture diaphragm 101 or a field diaphragm 101, and in other embodiments, the diaphragm 101 may also be disposed between the remaining adjacent two lenses, for example, between the second lens L2 and the third lens L3. The projection lens 100 of the present embodiment will be described in detail with reference to specific parameters.

First embodiment

Referring to fig. 1, fig. 1 is a schematic structural diagram of a projection lens 100 according to a first embodiment of the present application. The projection lens 100 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7, which are arranged in order from the object side to the image side along the optical axis O. The first lens element L1 through the seventh lens element L7 are made of glass.

Further, the first lens L1 has negative power, the second lens L2 has positive power, the third lens L3 has positive power, the fourth lens L4 has negative power, the fifth lens L5 has negative power, the sixth lens L6 has positive power, and the seventh lens L7 has positive power.

Furthermore, the object-side surface S1 and the image-side surface S2 of the first lens element L1 are respectively convex and concave at the paraxial region O, the object-side surface S3 and the image-side surface S4 of the second lens element L2 are respectively convex at the paraxial region O, the object-side surface S5 and the image-side surface S6 of the third lens element L3 are respectively convex and concave at the paraxial region O, the object-side surface S7 and the image-side surface S8 of the fourth lens element L4 are respectively convex and concave at the paraxial region O, the object-side surface S9 and the image-side surface S10 of the fifth lens element L5 are both concave at the paraxial region O, the object-side surface S11 and the image-side surface S12 of the sixth lens element L6 are both convex at the paraxial region O, and the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are both convex at the paraxial region O.

In the first embodiment, the effective focal length F of the projection lens 100 is 12.88mm, the projection ratio is 2, and the F-number FNO (i.e., F-number) is 2. Specifically, the parameters of the projection lens 100 are given in table 1 below. The elements from the object side to the image side along the optical axis O of the projection lens 100 are arranged in the order of the elements from top to bottom in table 1. In the same lens, the surface with the smaller surface number is the object side surface of the lens, and the surface with the larger surface number is the image side surface of the lens, and for example,

surface numbers

1 and 2 correspond to the object side surface and the image side surface of the first lens L1, respectively. The radii of curvature in table 1 are the radii of curvature of the object-side or image-side surfaces at the paraxial region O for the corresponding surface numbers. The first value in the "thickness" parameter list of a lens is the thickness of the lens on the optical axis O, and the second value is the distance from the image-side surface to the back surface of the lens on the optical axis O. The numerical value of the stop in the "thickness" parameter column is the distance on the optical axis O from the stop 101 to the vertex of the next surface (the vertex refers to the intersection point of the surface and the optical axis O), the direction from the object-side surface S1 of the first lens L1 to the image-side surface of the last lens is the positive direction of the optical axis O, when the value is negative, it indicates that the stop is disposed on the image-side of the vertex of the next surface, and when the thickness of the stop is positive, the stop is disposed on the object-side of the vertex of the next surface. It is understood that the unit of the radius of curvature, thickness, focal length in table 1 are all mm.

TABLE 1

In the first embodiment, the object-side surface and the image-side surface of the first lens L1 and the seventh lens L7 are both aspheric, and the surface shape x of the first lens L1 and the seventh lens L7 can be defined by, but is not limited to, the following aspheric formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis O direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius R of Y in table 1 above); k is a conic coefficient; ai is a correction coefficient corresponding to the high-order term of the ith aspheric term. Table 2 shows the coefficients a4, a6, a8, a10 of high-order terms that can be used for the object-side surface S1, the image-side surface S2 of the first lens L1, the object-side surface S13 of the seventh lens L7, and the image-side surface S14 in the first embodiment.

TABLE 2

Referring to fig. 2, fig. 2 shows a Modulation Transfer Function (MTF) graph of the projection lens 100 in the first embodiment, in which an abscissa along an X-axis direction in fig. 2 represents a spatial frequency in log lines/mm, and an ordinate along a Y-axis direction represents an MTF value. The MTF value is determined by taking the projection distance of the projection lens 100 as 100mm and the projection screen as 2.6 inches, and sampling is performed by taking the projection angle as the field of view. As can be seen from fig. 2, at a maximum spatial resolution of 67lp/mm, the MTF values in all fields are greater than 0.5, and the resolution of the projection lens 100 is better.

Referring to fig. 3, fig. 3 is a light ray spot diagram of the projection lens 100 in the first embodiment at 455nm, 520nm and 624 nm. The arrangement sequence of the regions 1-6 in fig. 3 is from left to right and from top to bottom. It should be noted that in the light ray dot diagram of the projection lens 100, the smaller the root mean square radius value and the geometric radius value are, the better the imaging quality of the projection lens 100 is. In the embodiment, as can be seen from fig. 3, the root mean square radius of the dot sequence diagrams under all the fields of view is smaller than 7.8um, that is, smaller than one pixel, and the projection lens 100 has better projection imaging quality.

Referring to fig. 4, (a), (B), and (C) in fig. 4 show the field curvature characteristic curves of the projection lens 100 in the first embodiment at wavelengths of 455nm, 520nm, and 624nm, and curves T and S are the tangential field curvature (tangential field curvature) characteristic curve and the sagittal field curvature (sagittal field curvature) characteristic curve, respectively, and it can be seen that the tangential field curvature value and the sagittal field curvature value at each wavelength are both controlled within the range of (-0.1mm, 0.1mm), which indicates that the field curvature of the projection lens 100 is better controlled.

Referring to fig. 5, fig. 5 is a graph showing distortion characteristics of the projection lens 100 at 455nm, 520nm, and 624nm in the first embodiment. As can be seen from fig. 5, the amount of distortion was controlled within a range of 0.1%.

Referring to fig. 6, fig. 6 is a vertical axis chromatic aberration diagram of the projection lens 100 in the first embodiment at 455nm, 520nm, and 624 nm. In fig. 6, the ordinate along the Y axis direction represents the vertical axis image height in mm, and the abscissa along the X axis direction represents the chromatic aberration in μm, as can be seen from fig. 6, the central field of view is less than 4um, the edge field of view is less than 3.58um, and is less than 0.7 pixel, and the vertical axis chromatic aberration is well corrected.

Second embodiment

Referring to fig. 7, fig. 7 is a schematic structural diagram of a projection lens 100 disclosed in a second embodiment of the present application. The projection lens 100 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7, which are arranged in order from the object side to the image side along the optical axis O. The first lens element L1 through the seventh lens element L7 are made of glass.

Further, in the second embodiment, the first lens L1 has a negative power, the second lens L2 has a positive power, the third lens L3 has a positive power, the fourth lens L4 has a negative power, the fifth lens L5 has a negative power, the sixth lens L6 has a positive power, and the seventh lens L7 has a positive power.

Furthermore, the object-side surface S1 and the image-side surface S2 of the first lens element L1 are respectively convex and concave at the paraxial region O, the object-side surface S3 and the image-side surface S4 of the second lens element L2 are both concave at the paraxial region O, the object-side surface S5 and the image-side surface S6 of the third lens element L3 are both convex at the paraxial region O, the object-side surface S7 and the image-side surface S8 of the fourth lens element L4 are both convex at the paraxial region O, the object-side surface S9 and the image-side surface S10 of the fifth lens element L5 are both concave at the paraxial region O, the object-side surface S11 and the image-side surface S12 of the sixth lens element L6 are both convex at the paraxial region O, and the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are both convex at the paraxial region O.

In the second embodiment, the effective focal length f of the projection lens 100 is 13.67 mm. The parameters in the second embodiment are given in table 3 below, and the definitions of the parameters can be obtained from the description of the foregoing embodiments, which are not repeated herein. It is understood that the unit of the radius of curvature, thickness, and focal length in table 3 are all mm.

TABLE 3

In the second embodiment, table 4 gives the high-order term coefficients that can be used for the first lens L1 and the seventh lens L7 in the second embodiment, in which the aspherical surface types of the first lens L1 and the seventh lens L7 can be defined by the formulas given in the first embodiment.

TABLE 4

Referring to fig. 8, fig. 8 is a graph showing a modulation transfer function of the projection lens 100 in the second embodiment, in which an abscissa in the X-axis direction of fig. 8 represents a spatial frequency in units of line pairs/mm and an ordinate in the Y-axis direction represents an MTF value. The MTF value is determined by taking the projection distance of the projection lens 100 as 100mm and the projection screen as 2.6 inches, and sampling is performed by taking the projection angle as the field of view. As can be seen from fig. 8, at a maximum spatial resolution of 67lp/mm, the MTF values in all fields are greater than 0.5, and the resolution of the projection lens 100 is good.

Referring to fig. 9, fig. 9 is a light ray diagram of the projection lens 100 in the second embodiment at 455nm, 520nm, and 624 nm. The arrangement sequence of the regions 1-6 in fig. 9 is from left to right and from top to bottom. It should be noted that in the light ray dot diagram of the projection lens 100, the smaller the root mean square radius value and the geometric radius value are, the better the imaging quality of the projection lens 100 is. In the embodiment, as can be seen from fig. 9, the root mean square radius value of the dot sequence diagram under all the fields of view is smaller than 7.8um, that is, smaller than one pixel, and the projection lens 100 has better projection imaging quality.

Referring to fig. 10, (a), (B), (C) in fig. 10 show the field curvature characteristic curves of the projection lens 100 in the second embodiment at 455nm, 520nm and 624nm, and curves T and S are the tangential field curvature (tangential field curvature) characteristic curve and the sagittal field curvature (sagittal field curvature) characteristic curve, respectively, and it can be seen that the tangential field curvature and the sagittal field curvature at each wavelength are controlled within the range of (-0.1mm, 0.1mm), which indicates that the field curvature of the projection lens 100 is better controlled.

Referring to fig. 11, fig. 11 is a graph showing distortion characteristics of the projection lens 100 at 455nm, 520nm, and 624nm in the second embodiment. As can be seen from fig. 11, the amount of distortion was controlled within a range of 0.1%.

Referring to fig. 12, fig. 12 is a diagram showing the vertical axis chromatic aberration of the projection lens 100 in the second embodiment at the wavelengths of 455nm, 520nm, and 624 nm. In fig. 12, the ordinate along the Y axis direction represents the vertical axis image height in mm, and the abscissa along the X axis direction represents the chromatic aberration in μm, as can be seen from fig. 12, the central field of view is less than 4um, the edge field of view is less than 5um, and is less than 0.7 pixel, and the vertical axis chromatic aberration is well corrected.

Referring to fig. 13, the present application further discloses a projection apparatus 200, where the projection apparatus 200 includes a light valve 201 and the projection lens 100 as described above, the light valve 201 is located at an image side of the projection lens 100, and the light valve 201 is configured to generate an image beam when being illuminated and emit the image beam to the projection lens 100. For example, the Light valve 201 may be a Digital Micro mirror Device (DMD) or a Liquid Crystal Spatial Light Modulator (LCSLM), and the prism 202 may be a right-angle prism 202, it can be understood that the projection apparatus 200 having the projection lens 100 can achieve short-distance projection imaging and ensure the quality of projection imaging.

Further, the projection apparatus 200 further includes a prism 202, the prism 202 is located between the light valve 201 and the projection lens 100, and the prism 202 can reflect the illumination light beam to the light valve 201, so that the light valve 201 generates an image light beam, and the image light beam is emitted to the projection lens 100 through the prism 202, and is transmitted to an image plane located on the object side of the projection lens 100 through the projection lens 100, so as to implement projection imaging. Illustratively, the prism 202 may be a right angle prism.

Further, the projection apparatus 200 further includes a protective glass 203, and the protective glass 203 is disposed on a side of the light valve 201 facing the prism 202. Since the protective glass 203 has high light transmittance and high intensity, providing the protective glass 203 on the side of the light valve 201 facing the prism 202 can protect the light valve 201 from the external environment without affecting the normal use of the light valve 201. Illustratively, the thickness of the cover glass 203 may be 1.1mm, although in other embodiments, the thickness of the cover glass 203 may take other values.

Referring to fig. 14, the present application further discloses an electronic device 300, wherein the electronic device 300 includes a housing 301 and the projection apparatus 200 as described above, and the projection apparatus 200 is disposed on the housing 301. The electronic device 300 may be, but is not limited to, a head-up display device, a projection guideboard, a game console, and the like. It can be understood that the electronic device 300 having the projection apparatus 200 also has all the technical effects of the projection apparatus 200, i.e. the quality of projection imaging can be ensured while realizing short-distance projection imaging.

Referring to fig. 15, the present invention discloses a vehicle 400, the vehicle 400 includes a vehicle body 401 and the electronic device 300 as described above, and the electronic device 300 is disposed on the vehicle body 401. Specifically, the electronic device 300 may be installed in a driving area of the vehicle body 401, and projects the navigation route or the speed of the vehicle 400 during driving onto a windshield of the vehicle body 401, so that a driver can view the above contents in time during driving. The vehicle 400 having the electronic device 300 can realize the short-distance projection imaging with high projection imaging quality in the limited space of the vehicle 400.

The projection lens, the projection device, the electronic device and the vehicle disclosed in the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by applying specific examples, and the description of the above embodiments is only used to help understand the projection lens, the projection device, the electronic device and the vehicle and their core ideas of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. The projection lens is characterized by comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are arranged from the object side to the image side along the optical axis in sequence;

the second lens has positive optical power;

the third lens has positive optical power;

the fourth lens has a negative optical power;

the fifth lens has a negative optical power;

2. The projection lens of claim 1 wherein the projection lens satisfies the relationship: -3. ltoreq. f 1/f.ltoreq.0.5, 0. ltoreq. f 2/f.ltoreq.1.5, 0.5. ltoreq. f 3/f.ltoreq.2.5, -4. ltoreq. f 4/f.ltoreq.1.5, -2. ltoreq. f 5/f.ltoreq.0, 0.5. ltoreq. f 6/f.ltoreq.3.5 and 0.2. ltoreq. f 7/f.ltoreq.3.5;

wherein f is an effective focal length of the projection lens, f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens, f4 is a focal length of the fourth lens, f5 is a focal length of the fifth lens, f6 is a focal length of the sixth lens, and f7 is a focal length of the seventh lens.

3. The projection lens as claimed in claim 1, wherein the object-side surface of the second lens element is convex at a paraxial region and the image-side surface of the second lens element is convex at a paraxial region.

4. The projection lens of claim 1 wherein the third lens and the fourth lens are cemented to form a cemented lens with negative power.

5. The projection lens of claim 1 further comprising a stop between the fourth lens and the fifth lens.

6. A projection apparatus, comprising a projection lens according to any one of claims 1 to 5 and a light valve disposed on an image side of the projection lens, the light valve being configured to generate an image beam and direct the image beam to the projection lens.

7. The projection device of claim 6, further comprising a prism located between the light valve and the projection lens, the prism configured to reflect an illumination beam to the light valve such that the light valve generates the image beam, and the prism configured to emit the image beam to the projection lens.

8. The projection device of claim 7, further comprising a cover glass disposed on a side of the light valve facing the prism.

9. An electronic device, characterized in that the electronic device comprises a housing and a projection device according to any one of claims 6-8, which is provided to the housing.

10. A vehicle characterized by comprising a vehicle body and the electronic apparatus according to claim 9, the electronic apparatus being provided to the vehicle body.