CN112540442B - Projection lens, focusing method and device of projection lens and projector - Google Patents

Abstract

The invention discloses a projection lens, a focusing method and device of the projection lens and a projector, and belongs to the field of projection. The projection lens comprises a first lens group, a second lens group, a third lens group, a first lens barrel, a second lens barrel and a third lens barrel, wherein the first lens barrel, the second lens barrel and the third lens barrel are sequentially arranged along the light emitting direction of a light valve of a projector where the projection lens is located, the first lens group is positioned in the first lens barrel, the second lens group is positioned in the second lens barrel, the third lens group is positioned in the third lens barrel, the first lens group, the second lens group and the third lens group share an optical axis, the second lens group comprises n lenses, n is more than or equal to 1 and less than or equal to 2, and the n lenses are all configured to be connected with a driving assembly in the projector where the second lens group is located and move along the optical axis of the second lens group under the control of the driving assembly so as to change the image distance of the projection lens. The invention can simplify the focusing process of the projection lens. The invention is used for focusing the projection lens.

Description

Projection lens, focusing method and device of projection lens and projector

Technical Field

The present invention relates to the field of projection, and in particular, to a projection lens, a focusing method and device for the projection lens, and a projector.

Background

The laser display projection technology is a novel display projection technology in the current market. The laser projector applying the technology can realize the automatic focusing function, and the laser projector capable of realizing the automatic focusing function is also called an automatic focusing projector. Focusing refers to adjusting the image distance of a projector by adjusting the position of the focus of the projector.

The focusing projector comprises a driving assembly and a projection lens, wherein the projection lens comprises a focusing lens group for focusing. When the projection lens projects to the screen and the distance between the projection lens and the screen is changed, the driving assembly can control each focusing lens in the focusing lens group to move along the optical axis of the focusing lens group according to the corresponding relation between the preconfigured distance and the image distance.

However, the number of lenses in the focusing lens group of the current focusing projector is large, the number of lenses is generally greater than six, and a non-focusing lens is generally arranged between two focusing lenses of the focusing lens group. Therefore, the number of lenses to be controlled by the driving assembly in the focusing process is large, and the focusing lenses arranged at intervals need to be controlled to move, so that the focusing process is complex.

Disclosure of Invention

The invention provides a projection lens, a focusing method and device of the projection lens and a projector, which can simplify the focusing process of the projection lens, and the technical scheme is as follows:

In a first aspect, a projection lens is provided, the projection lens including a first lens group, a second lens group, a third lens group, a first barrel, a second barrel, and a third barrel;

The first lens cone, the second lens cone and the third lens cone are sequentially arranged along the light emitting direction of a light valve of a projector where the projection lens is located, the first lens group is positioned in the first lens cone, the second lens group is positioned in the second lens cone, the third lens group is positioned in the third lens cone, and the first lens group, the second lens group and the third lens group share an optical axis;

the second lens group comprises n lenses, n is more than or equal to 1 and less than or equal to 2, and the n lenses are all configured to be connected with a driving component in a projector where the n lenses are positioned and move along the optical axis of the second lens group under the control of the driving component so as to change the image distance of the projection lens.

In a second aspect, a focusing method of a projection lens is provided, and the focusing method is applied to a driving assembly in a projector, where the projection lens is any one of the projection lenses in the first aspect, and the driving assembly is connected to n lenses in the second lens group, and the method includes:

and controlling the n lenses to move along the optical axis of the second lens group so as to change the image distance of the projection lens.

In a third aspect, there is provided a focusing apparatus of a projection lens including respective modules for performing the focusing method of the projection lens of any one of the second aspects.

In a fourth aspect, a focusing apparatus for a projection lens is provided, comprising a processor, and a memory for storing executable instructions of the processor;

the processor is capable of implementing the focusing method of the projection lens according to any one of the second aspect when executing the executable instructions.

In a fifth aspect, a computer-readable storage medium having instructions stored therein is provided;

When the instructions are executed on the processing component, the processing component is caused to execute the focusing method of the projection lens according to any one of the second aspects.

In a sixth aspect, there is provided a projector comprising a drive assembly, a light valve, and the projection lens of any of the first aspects;

the light valve, the first lens group, the second lens group and the third lens group are sequentially arranged;

The drive assembly is coupled to each lens in the second lens group and is configured to control movement of each lens along an optical axis of the second lens group.

The technical scheme provided by the invention can comprise the following beneficial effects:

according to the projection lens, the focusing method and device of the projection lens and the projector, the second lens group in the second lens barrel in the projection lens comprises at most two lenses, and each lens in the second lens group can move along the optical axis of the second lens group under the control of the driving component so as to change the image distance of the projection lens. The number of lenses to be controlled by the driving assembly is small, and the driving assembly does not need to control the lenses arranged at intervals to move so as to change the image distance of the projection lens, so that the focusing process is simplified.

Drawings

In order to more clearly illustrate the embodiments of the present invention, the drawings that are required for the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.

Fig. 1 is a schematic view of an application environment of a projector according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a projection lens according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an image contrast simulation interface of a projection lens according to an embodiment of the present invention when the frame size is 100 inches;

FIG. 4 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 5 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 6 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 7 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 8 is a diagram of an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 9 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 10 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 11 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 12 is a diagram showing an integrated error of an image on a sagittal view fan when a projection lens is 100 inches in size;

FIG. 13 is a diagram showing an integrated error of an image on a sagittal view fan when the frame size of the projection lens is 100 inches according to an embodiment of the present invention;

FIG. 14 is a diagram showing the integrated error of images on a meridian fan when the size of the projection lens is 100 inches;

FIG. 15 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 16 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 17 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 18 is a diagram showing the integrated error of images on a meridian fan when the size of the projection lens is 100 inches;

FIG. 19 is a diagram showing the integrated error of an image on a meridian fan when the size of a projection lens is 100 inches;

FIG. 20 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 21 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 22 is a diagram of integrated errors of images on a meridian fan when the size of a projection lens is 100 inches;

FIG. 23 is a diagram showing the integrated error of images on a meridian fan when the size of the projection lens is 100 inches;

Fig. 24 is a flowchart of a focusing method of a projection lens according to an embodiment of the present invention;

FIG. 25 is a block diagram of a focusing apparatus for a projection lens according to an embodiment of the present invention;

FIG. 26 is a block diagram of a focusing apparatus for a projection lens according to an embodiment of the present invention;

FIG. 27 is a schematic diagram showing the image beam direction of a projector according to an embodiment of the present invention when the frame size is 100 inches;

Fig. 28 is a schematic diagram of an imaging optical path of a projector according to an embodiment of the present invention.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Fig. 1 is a schematic view of an application environment of a projector according to an embodiment of the present invention, referring to fig. 1, the application environment includes a projector 1 and a screen 2. The projector 1 may comprise a light valve 10, a total internal reflection (total internal reflection, TIR) prism 20 and a projection lens 30 arranged in this order, the projection lens 30 comprising a refractive system S1 and a reflective system S2 arranged in this order in a direction away from the TIR prism 20.

Wherein the light valve 10 is used for generating an image beam when being irradiated by light. Illustratively, the light valve 10 may be a digital micromirror device (digital micro mirror device, DMD) that may have a resolution of 2K resolution (meaning that the pixel values per row of the device reach or are close to 2000), 3K resolution (meaning that the pixel values per row of the device reach or are close to 3000), or 4K resolution (meaning that the pixel values per row of the device reach or are close to 4096).

The TIR prism 20 is used for reflecting the image beam to the refraction system S1 in the projection lens 30 to improve brightness and contrast of the image beam entering the refraction system S1. The TIR prism 20 may be, for example, 2 total reflection prisms, or 2a total reflection prisms, a being an integer greater than 1.

The refraction system S1 is configured to refract the image beam entering the refraction system S1 into the reflection system S2, where the image beam is first imaged between the refraction system S1 and the reflection system S2 (i.e., the image beam forms a convergence point between the refraction system S1 and the reflection system S2).

After the first imaging, the reflection system S2 is configured to project the image beam output by the refraction system S1 onto the screen 2, so as to display a large-sized projection screen on the screen 2. For example, the reflection system S2 may correct the distortion aberration of the image beam refracted by the refraction system S1, and then project the image beam onto the screen, so as to display an undistorted projection screen on the screen.

Optionally, as shown in FIG. 1, the projector 1 may further include an image shifting lens group 40 disposed between the TIR prism 20 and the projection lens 30. The image offset lens set 40 is used for performing an offset process on the image beam reflected by the TIR prism 20, and then transmitting the image beam after the offset process to the projection lens, so as to improve the resolution of the picture finally reflected onto the projection screen. The image offset optics 40 may be, for example, a plate-like transparent device, such as a plate transparent glass. When the image offset lens group 40 works, the image offset lens group 40 can be driven by a motor and other devices to vibrate at high frequency, so that the offset of the image light beams is realized, the projection images are overlapped in a staggered manner through the staggered superposition of the image light beams corresponding to two continuous projection images, and the clear projection images are watched by human eyes by utilizing the visual persistence effect of the human eyes, so that the projection display resolution is improved.

In the embodiment of the present invention, the projector 1 may be a projector capable of focusing (also referred to as a focusing projector), and accordingly, the projection lens 30 includes a focusing lens group for focusing. Illustratively, as shown in FIG. 1, the projector 1 may further include a drive assembly 50. When the projection lens 30 projects toward the screen and the distance between the projection lens 30 and the screen is changed, the driving assembly 50 can control each of the focusing lens groups to move along the optical axis of the focusing lens group according to the pre-configured correspondence between the distance and the image distance.

However, in the related art, the number of lenses in the focusing lens group is large, typically, the number of lenses is larger than 6, and typically, a non-focusing lens is disposed between two focusing lenses of the focusing lens group. Therefore, the number of lenses to be controlled by the driving assembly in the focusing process is large, and the focusing lenses arranged at intervals need to be controlled to move, so that the focusing process is complex.

Fig. 2 is a schematic structural diagram of a projection lens according to an embodiment of the present invention, and the projection lens can be applied to the projector 1 shown in fig. 1. Referring to fig. 2, the projection lens 30 includes a first lens group 301, a second lens group 302, a third lens group 303, a first barrel 3051, a second barrel 3052, and a third barrel 3053. The first lens barrel 3051, the second lens barrel 3052 and the third lens barrel 3053 are sequentially arranged along a light emitting direction X of a light valve of a projector where the projection lens is located. The first lens group 301 is located in the first lens barrel 3051, the second lens group 302 is located in the second lens barrel 3052, the third lens group 303 is located in the third lens barrel 3053, and lenses in the respective lens groups can only move in the lens barrel in which they are located. The first lens group 301, the second lens group 302 and the third lens group 303 share an optical axis L. The second lens group 302 includes n lenses, 1 n 2, and fig. 2 illustrates that the second lens group 302 includes two lenses. The n lenses are each configured to be connected to a driving assembly in the projector in which they are located and to move along the optical axis L of the second lens group 302 under the control of the driving assembly to change the image distance of the projection lens 30. The image distance of the projection lens refers to the distance from the main plane of the projection lens to the screen projected by the projection lens.

In summary, in the projection lens provided by the embodiment of the invention, the second lens group located in the second lens barrel includes at most two lenses, and each lens in the second lens group can move along the optical axis of the second lens group under the control of the driving component so as to change the image distance of the projection lens. The number of lenses to be controlled by the driving assembly is small, and the driving assembly does not need to control the lenses arranged at intervals to move so as to change the image distance of the projection lens, so that the focusing process is simplified.

It should be noted that, in the embodiment of the present invention, the projection lens includes the first lens group, the second lens group and the third lens group as an example, in practice, the projection lens may also include other structures, which is not limited in the embodiment of the present invention.

Alternatively, the second lens group 302 may include two lenses (n=2). As illustrated in fig. 2, the second lens group 302 may include a first spherical lens 3021 with positive power and a second spherical lens 3022 with negative power sequentially arranged along the light emitting direction of the light valve of the projector in which the projection lens is located, where the first spherical lens 3021 is close to the first lens group 301 and the second spherical lens 3023 is close to the third lens group 303.

In general, when the size of a picture projected by the projection lens is adjustable, the vertical distance (also referred to as the projection distance) between the point of the projection lens from which the image beam exits and the screen also changes, and accordingly, the picture projected by the projection lens is not clear. In order to make projection pictures of various sizes clear, focusing of the projection lens is required. In the embodiment of the present invention, when focusing the projection lens, the first lens group 301 and the third lens group 303 are kept stationary, and each lens in the second lens group 302 moves along the optical axis L of the second lens group 302 under the control of the driving component, so as to change the image distance of the projection lens 30.

For example, when the projection distance becomes large such that the size of the screen becomes small with respect to 100 inches, based on the size of the screen projected by the projection lens, the first spherical lens 3021 and the second spherical lens 3022 move in a direction away from the first lens group 301 along the optical axis L of the second lens group 302 during focusing. When the projection distance becomes small so that the size of the screen becomes large with respect to 100 inches, the first spherical lens 3021 and the second spherical lens 3022 move in a direction approaching the first lens group 301 along the optical axis L of the second lens group 302 during focusing. Wherein the moving distances of the first spherical lens 3021 and the second spherical lens 3022 may be different.

Alternatively, the first lens group 301 may include m lenses, where m is a positive integer, and 6+.m <16. For example, the first lens group 301 may include 6 lenses, or 7 lenses or 11 lenses.

When the first lens group 301 includes 11 lenses, the first lens group 301 may include 2 aspherical lenses and 9 spherical lenses. For example, as shown in FIG. 2, the first lens group 301 includes a third spherical lens 3011 of positive power, a fourth aspherical lens 3012 of positive power, a triple cemented spherical lens 3013 of positive power (composed of three spherical lenses cemented by a cement), a fifth spherical lens 3014 of negative power, a sixth spherical lens 3015 of positive power, a seventh spherical lens 3016 of negative power, an eighth aspherical lens 3017 of positive power, and a double cemented spherical lens 3018 of negative power (composed of two spherical lenses cemented by a cement) arranged in this order. Wherein the third spherical lens 3011 is far away from the second lens group 302, and the cemented spherical lens 3018 is near the second lens group 302.

Fig. 2 shows a case where the first lens group 301 includes 11 lenses, and when the first lens group 301 includes 6 lenses, the first lens group 301 may include 1 aspherical lens and 5 spherical lenses. For example, the first lens group 301 may include a triple cemented spherical lens with positive power, a third aspherical lens with positive power, and a double cemented spherical lens with negative power, which are sequentially arranged, wherein the triple cemented spherical lens is far from the second lens group 302, and the double cemented spherical lens is near to the second lens group 302.

When the first lens group 301 includes 7 lenses, the first lens group 301 may include 2 aspherical lenses and 5 spherical lenses. For example, the first lens group 301 may include a third aspherical lens with positive power, a triple cemented spherical lens with positive power, a fourth aspherical lens with positive power, and a double cemented spherical lens with negative power, which are sequentially arranged, wherein the third aspherical lens is far from the second lens group 302, and the double cemented spherical lens is close to the second lens group 302.

As shown in fig. 2, the triple cemented spherical lens 3013 may include a ninth spherical lens a1 of positive power, a tenth spherical lens a3 of negative power, and an eleventh spherical lens a3 of positive power, which are sequentially arranged in a direction close to the second lens group 302. The cemented spherical lens 3018 may include a twelfth spherical lens a4 of negative power and a thirteenth spherical lens a5 of positive power arranged in order in a direction close to the second lens group 302.

The triple cemented spherical lens 3013 and the double cemented spherical lens 3018 are mainly used for correcting chromatic aberration (including axial chromatic aberration and vertical chromatic aberration) of a projection lens, and have a certain correction capability for monochromatic aberration (such as spherical aberration, coma, astigmatism, curvature of field, or distortion) of the projection lens. The image light beam sequentially passes through the three cemented spherical lens 3013 and the two cemented spherical lens 3018, and after the three cemented spherical lens 3013 corrects the chromatic aberration of the projection lens, the two cemented spherical lens 3018 further accurately corrects the residual chromatic aberration of the projection lens. Wherein the power of the twelfth spherical lens a4 included in the bi-cemented spherical lens 3018 is negative and the power of the thirteenth spherical lens a5 is positive, so that the positive chromatic aberration generated by the image beam through the twelfth spherical lens a4 and the negative chromatic aberration generated by the thirteenth spherical lens a5 cancel each other out, thereby correcting the chromatic aberration of the image beam to 0. The positions of the triple cemented spherical lens 3013 and the double cemented spherical lens 3018 in the projection lens may be interchanged, which is not limited in the embodiment of the present invention.

Alternatively, the third lens group 303 may include n lenses, n is a positive integer, and 2< n <5. For example, the third lens group 303 may include 3 lenses, and in this case, the third lens group 303 may include 1 aspherical lens and 2 spherical lenses. For example, as shown in FIG. 2, the third lens group 303 may include a fourteenth spherical lens 3031 of positive power, a fifteenth spherical lens 3032 of negative power, and a sixteenth aspherical lens 3033 of negative power, which are arranged in order. Wherein the fourteenth spherical lens 3031 is close to the second lens group 302, and the sixteenth aspherical lens 3033 is far from the second lens group 302.

Typically, the lens of the projection lens is made of glass material. However, the glass material is expensive and the processing process is complicated when the aspherical lens is made of the glass material. Since the sixteenth aspheric lens 3033 is further away from the light valve, and has a larger aperture and is more consumable, the sixteenth aspheric lens 3033 can be made of plastic, such as 480R (a plastic type). The price of the plastic material is lower, and the processing technology is simpler when the aspherical lens is made of the plastic material. For example, the aspherical lens may be made of plastic material by molding.

The projection lens provided by the embodiment of the invention comprises 3 aspheric lenses in total, wherein the 3 aspheric lenses are respectively a fourth aspheric lens 3012, an eighth aspheric lens 3017 and a sixteenth aspheric lens 3033. The symmetrical aspheric lens is convenient to process and manufacture due to the regular shape, and particularly the rotationally symmetrical aspheric lens is easier to process and manufacture. Therefore, when the 3 aspheric lenses in the projection lens are all in a rotationally symmetrical structure, the processing process of the projection lens can be simplified, and the processing cost can be reduced.

The 3 aspherical lenses are mainly used for correcting aberration of the projection lens. The fourth aspherical lens 3012 can be used to correct coma, astigmatism, and curvature of field of a projection lens, for example. The eighth aspherical lens 3017 can be used to correct spherical aberration and curvature of field of a projection lens. The sixteenth aspherical lens 3033 can be used to correct astigmatism, field curvature, and distortion of the projection lens. The distortion affects the shape of the picture projected by the projection lens, and coma, astigmatism, field curvature, spherical aberration, and the like affect the definition of the picture projected by the projection lens. The 3 aspheric lenses can correct coma, astigmatism, field curvature, spherical aberration and distortion, so that the display effect of a picture projected by the projection lens is improved.

Optionally, the projection lens may further comprise an aperture stop (not shown in FIG. 2) located between any two lenses of the first lens group 301. Illustratively, the aperture stop is located between the fifth and sixth spherical lenses 3014 and 3015 in the first lens group. The aperture diaphragm is used for limiting the aperture of an incident transmission pupil so as to control the correction of the aberration of the projection lens by other structures in the projection lens.

Since the aperture stop is mainly used for limiting the aperture of the incident transmission pupil, the temperature near the aperture stop is high because the energy density distribution around the aperture stop is high. Therefore, in order to reduce the influence of the temperature near the aperture stop on the mirror plates (for example, the fifth spherical lens 3014 and the sixth spherical lens 3015), the mirror plates near the aperture stop need to be selected from materials having a small expansion coefficient. For example, the lens may be manufactured from a glass material of the type L-TIM28, L-AM69HE, and L-LALB, and the material having a smaller expansion coefficient may reduce the change in the lens surface shape (i.e., R value, i.e., radius of curvature of the lens) due to temperature changes, thereby reducing the influence of temperature drift on the projection lens.

It should be noted that, the projection lens provided in the embodiment of the present invention includes a refraction system and a reflection system sequentially arranged, where the refraction system includes the first lens group 301, the second lens group 302, and the third lens group 303. As shown in fig. 2, the reflection system includes an aspherical mirror 304 of positive power, the aspherical mirror 304 being adjacent to the third lens group 303 for reflecting the image beam refracted by the third lens group 303 onto a screen for display by the screen.

In the projection lens, the focal power of each lens can directly influence astigmatism, field curvature, distortion, axial chromatic aberration and vertical chromatic aberration, so that different positive and negative focal power collocations can play a certain role in aberration correction. In the projection lens provided by the embodiment of the invention, when the first lens group 301 includes 11 lenses, the optical power of the first lens group 301 is positive, negative, and positive, when the second lens group 303 includes two lenses, the optical power of the second lens group 302 is positive and negative, and when the third lens group 303 includes 3 lenses, the optical power of the third lens group 303 is positive, negative, and negative. Wherein the total focal power of the refraction system is positive focal power, and the total focal power of the reflection system is positive focal power. This ensures that the lens of the projection lens has the best effect on correcting aberrations.

Optionally, the projection lens provided by the embodiment of the invention can satisfy at least one condition 1 that the ratio of the effective focal length of the first lens group 301 to the effective focal length of the projection lens is a, and a is more than or equal to 2 and less than or equal to 12. And 2, the ratio of the effective focal length of the second lens group to the effective focal length of the projection lens is b, wherein b is more than or equal to 20 and less than or equal to 35. And 3, the ratio of the effective focal length of the third lens group to the effective focal length of the projection lens is c, wherein c is more than or equal to 25 and less than or equal to 35. The effective focal length of the projection lens is the distance from the main image plane to the paraxial image plane after the projection lens. The effective focal length of each lens group is the distance from the back main image surface of the lens group to the paraxial image surface. When the projection lens meets the at least one condition, the display effect of the picture projected by the projection lens on the screen is better.

Alternatively, the effective focal length of the projection lens may be d, and 2.34 millimeters (mm). Ltoreq.d.ltoreq. 2.370 millimeters. For example, the effective focal length of the projection lens may be 2.34mm, and the projection lens is an ultra-short focal projection lens. Still alternatively, the size of the frame projected by the projection lens may be 90 to 120 inches, and accordingly, the projection ratio of the projection lens may be e, and 0.23.ltoreq.e.ltoreq.0.24. For example, the projection lens may have a throw ratio of 0.24. The projection ratio of the projection lens is the ratio of the projection distance to the width of the projection screen, i.e., the projection distance/screen width. The projection ratio reflects the ultra-short focal characteristics of the lens. Compared with the traditional non-ultra-short-focus projector, the ultra-short-focus projection lens has smaller projection (less than 1), so that the projection lens can be placed at a position close to a projection screen, a large amount of space is saved, and shielding of image light beams when the projection lens needs to be close to the projection screen is avoided.

In the related art, since the number of focusing lenses for focusing is large and there may be a non-focusing lens between two focusing lenses, a plurality of focusing lenses are usually located at different positions in the projection lens. This results in a larger aberration to be corrected by the focusing lens, thereby causing an influence on the projection effect of the projection lens easily in the course of focusing the projection lens. In the embodiment of the present invention, the number of focusing lenses used for focusing is 2 at the maximum, and all the focusing lenses are disposed at the middle position of the projection lens (i.e., disposed in the second lens barrel). Since the image beam passes through the first lens group 301 and then passes through the second lens group 302, most of the aberration of the projection lens is corrected by the first lens group 301. This makes the aberration to be corrected by the second lens group 302 smaller, and thus makes the effect of imaging the projection lens less affected in focusing the projection lens. It can realize 4K high-resolution imaging under the 90-120 inch picture by only moving two lenses.

The resolution of the projection lens provided by the embodiment of the invention can be 93 line pairs/millimeter (lp/mm) (namely, the resolution required by 4K resolution), so that the projection lens can analyze the image with the 4K resolution, the projection screen can display a higher-definition image, and the user experience is improved. The total length of the refractive system of the projection lens is L1 (i.e., the distance from the edge surface of the side of the third spherical lens 3011 near the light valve to the edge surface of the side of the sixteenth aspherical lens 3033 near the reflective system in fig. 2), and the distance between the refractive system and the reflective system is L2, where 1.37< L1/L2<1.57, since the thickness of the lens in the reflective system is negligible, the L2 can be the total length of the projection lens minus the value of L1.

Because of the reduction of the number of lenses used for focusing, the number of lenses used for the projection lens provided by the embodiment of the invention is 16, so that the length of the projection lens ranges from 177mm to 185mm, for example, the length of the projection lens can be 177mm. The number of lenses of the projection lens capable of focusing in the related art is about 20, and the length of the projection lens is at least 210mm. Therefore, the maximum projection length of the projection lens capable of focusing provided by the embodiment of the invention is smaller than that of the projection lens capable of focusing in the related art. The maximum caliber of the lens in the projection lens is 50mm, the maximum caliber of the lens in the projection lens in the related art is 60mm, and the maximum caliber of the lens is smaller than the maximum caliber of the projection lens in the related art. Therefore, the projection lens capable of focusing provided by the embodiment of the invention has smaller overall volume.

Referring to fig. 3, fig. 3 is a schematic diagram of an imaging contrast simulation interface of a projection lens with a frame size of 100 inches according to an embodiment of the present invention, which is also a distortion analysis diagram of a projector. Referring to fig. 3, the intersection point of the horizontal line and the vertical line is a pre-imaging position, and the cross (x) is the imaging position of the actual projection lens, the higher the coincidence rate of the intersection point and the cross is, the lower the imaging distortion value is, and the lower the imaging distortion degree is. Assuming that the wavelength of the image beam is 0.5500 micrometers (μm), the zoom ratio is 1, and as shown in fig. 3, when the projection screen is 100 inches (2214×1245mm ²), the maximum distortion value obtained by simulation in the simulation interface is-1.032%. Thus, as can be seen from fig. 3, the degree of distortion of the imaging of the projection lens is low. It should be noted that, the embodiment of the invention only shows the schematic diagram of the imaging contrast simulation interface of the projection lens when the image size is 100 inches. The schematic diagram of the imaging contrast simulation interface of the projection lens with a frame size of 90 inches and the schematic diagram of the imaging contrast simulation interface with a frame size of 120 inches can be referred to fig. 3, and the embodiments of the present invention will not be described herein.

Referring to fig. 4 to 23, fig. 4 to 13 are image integrated error diagrams on a sagittal fan normalized under 10 different fields of view when a frame size is 100 inches, and fig. 14 to 23 are image integrated error diagrams on a meridional fan normalized under 10 different fields of view when a frame size is 100 inches. Each of fig. 4 to 13 is used to show the difference between 3 wavelengths of light and the dominant wavelength of light (i.e., the light passing through the light emitting point and the center point of the aperture) on the image plane under a viewing field condition when the projection screen is 100 inches. The 3 light rays have wavelengths of 0.45 μm, 0.55 μm and 0.62 μm, respectively.

As shown in fig. 4 to 13, the sagittal fan is a beam profile passing through the X-axis of the pupil. In the coordinate system of the image integrated error map on the sagittal light sector, the horizontal axis PX is used to represent the normalized height of the light intake pupil on the sagittal light sector, which ranges from-1 to 1. The vertical axis EX is used to indicate the difference between the height of the image plane and the height of the principal ray of the current field of view on the image plane when the light passing through the designated pupil in the sagittal fan plane is incident on the image plane, and the unit of the difference is μm. In each figure, the higher the coincidence ratio of the curves in the coordinate axis plane where EX and PX are located, the smaller the chromatic aberration of the projection lens. The smaller the aberration of the projection lens is as the curve approaches the PX axis.

As shown in fig. 14 to 23, the meridional fan plane is a beam profile passing through the Y-axis of the pupil. In the coordinate system of the image integrated error map on the meridional light sector, the horizontal axis PY is used to represent the normalized height of the light intake pupil on the meridional light sector, which ranges from-1 to 1. The vertical axis EY is used to indicate the difference between the height of the image plane, through which light rays at a specified pupil in the meridional fan plane are incident, and the height of the principal ray of the field of view, which is given in μm. In each figure, the higher the coincidence ratio of the curves in the coordinate axis plane where EY and PY are located, the smaller the chromatic aberration of the projection lens. The aberration of the projection lens is smaller as the curve approaches the PY axis.

It should be noted that, the embodiment of the present invention only shows the image integrated error map on the sagittal fan normalized under 10 different fields of view when the screen size of the projection lens is 100 inches, and the image integrated error map on the meridional fan normalized under 10 different fields of view when the screen size of the projection lens is 100 inches. The image integrated error map of the projection lens on the sagittal view fan at a screen size of 90 inches and the image integrated error map of the projection lens on the sagittal view fan at a screen size of 120 inches are similar to those of fig. 4 to 13, and thus reference is made to fig. 4 to 13. The integrated error map of the image on the meridian optical fan when the image size of the projection lens is 90 inches and the integrated error map of the image on the meridian optical fan when the image size of the projection lens is 120 inches are similar to those of fig. 14 to 23, so reference may be made to fig. 14 to 23, and detailed description of the embodiments of the present invention is omitted here. As can be seen from fig. 4 to 23, when the projection screen is 100 inches, the coincidence ratio of the curves is higher in the image integrated error map on the sagittal fan surface and the image integrated error map on the meridional fan surface in each view, and is closer to the PY axis or the PX axis, so that the chromatic aberration and the aberration of the projection lens are smaller. Similarly, when the projection screen is 90 inches or 120 inches, the chromatic aberration and aberration of the projection lens are also smaller.

In summary, in the projection lens provided by the embodiment of the invention, the second lens group in the second lens barrel includes at most two lenses, and each lens in the second lens group can move along the optical axis of the second lens group under the control of the driving component so as to change the image distance of the projection lens. The number of lenses to be controlled by the driving assembly is small, and the driving assembly does not need to control the lenses arranged at intervals to move so as to change the image distance of the projection lens, so that the focusing process is simplified.

Furthermore, the refraction system of the projection lens provided by the embodiment of the invention comprises a three-cemented lens and a double-cemented lens, and the three-cemented lens and the double-cemented lens are mutually matched with other lenses, so that the projection lens has higher chromatic aberration and aberration correction capability, the number of conventional lens and lens combinations can be greatly reduced, the number of the integral lenses of the projection lens is correspondingly reduced while the projection lens has higher resolution power, the length of the projection lens is effectively shortened, and the projection lens with miniaturized volume is facilitated. And for the aspherical lens, the plastic material is easy to process and has low price, so the twelfth aspherical lens can be made of plastic, thereby reducing the processing cost of the projection lens and reducing the processing difficulty of the projection lens.

The embodiment of the invention provides a focusing method of a projection lens, which can be applied to a driving component in a projector, wherein the projection lens can be any one of the projection lenses provided by the embodiment of the invention, and the driving component is connected with n lenses in a second lens group of the projection lens. Referring to fig. 24, the method includes:

Step 201, controlling the n lenses to move along the optical axis of the second lens group so as to change the image distance of the projection lens.

Referring to fig. 2, the second lens group 302 may include a first spherical lens 3021 and a second spherical lens 3022 sequentially arranged along the light emitting direction of the light valve. Optionally, a distance sensor may be disposed at an end of the projector where the projection lens is located, where the end is close to the screen, and the distance sensor is used to detect a distance between the projection lens and the screen. Before the driving assembly controls the n lenses to move along the optical axis of the second lens group, the distance change between the projection lens and the screen can be determined through the distance sensor, and then the n lenses are controlled to move along the optical axis of the second lens group according to the distance change condition between the projection lens and the screen. Alternatively, the distance sensor may be disposed at other positions of the projection lens, which is not limited in the embodiment of the present invention.

For example, referring to fig. 2, when the driving component determines that the distance between the projection lens and the screen becomes larger through the distance sensor, the driving component may control the first spherical lens and the second spherical lens to move along the optical axis of the second lens group in a direction away from the first lens group. When the driving component determines that the distance between the projection lens and the screen is reduced through the distance sensor, the driving component can control the first spherical lens and the second spherical lens to move along the optical axis of the second lens group towards the direction close to the first lens group.

In summary, in the focusing method of the projection lens provided by the embodiment of the invention, the driving assembly can control all lenses in the second lens group to move along the optical axis of the second lens group so as to change the image distance of the projection lens. Since the second lens group positioned on the second lens barrel comprises at most two lenses, the number of the lenses which are required to be controlled by the driving assembly is small, and the driving assembly does not need to control the lenses which are arranged at intervals to move so as to change the image distance of the projection lens, so that the focusing process is simplified.

Having described the focusing method of the projection lens according to the embodiment of the present invention, the focusing apparatus of the projection lens according to the embodiment of the present invention is described below, and the focusing apparatus of the projection lens according to the embodiment of the present invention may be applied to a driving assembly, which may be the driving assembly 10 shown in fig. 1. It should be appreciated that the focus adjustment device of the projection lens applied to the driving assembly may be the driving assembly in the above method, which has any of the functions of the driving assembly in the above method.

Fig. 25 is a block diagram of a focusing apparatus for a projection lens according to an embodiment of the present invention, and the focusing apparatus 300 for a projection lens can be applied to a driving assembly of the projector 1 shown in fig. 1. Referring to fig. 25, the apparatus 300 includes:

The control module 301 is configured to control the n lenses to move along the optical axis of the second lens group so as to change the image distance of the projection lens.

Alternatively, the control module 301 may include a control sub-module and a physical structure (e.g. a motor), where the physical structure is connected to the n lenses, and the physical structure can move under the control of the control sub-module to drive the n lenses to move along the optical axis of the second lens group.

Optionally, the second lens group includes a first spherical lens and a second spherical lens sequentially arranged along the light emitting direction of the light valve, and the control module 301 is configured to:

when the projection lens projects to the screen and the distance between the projection lens and the screen is increased, the first spherical lens and the second spherical lens are controlled to move along the optical axis of the second lens group in a direction away from the first lens group.

When the projection lens projects to the screen and the distance between the projection lens and the screen becomes smaller, the first spherical lens and the second spherical lens are controlled to move along the optical axis of the second lens group towards the direction close to the first lens group.

In summary, in the focusing device of the projection lens provided by the embodiment of the invention, the control module can control all lenses in the second lens group to move along the optical axis of the second lens group so as to change the image distance of the projection lens. The second lens group positioned on the second lens barrel comprises at most three lenses, so that the number of the lenses which are required to be controlled by the control module is small, and the control module does not need to control the lenses which are arranged at intervals to move so as to change the image distance of the projection lens, thereby simplifying the focusing process.

Fig. 26 is a block diagram of a focusing apparatus for a projection lens according to an embodiment of the present invention, referring to fig. 26, the focusing apparatus 400 for a projection lens includes a processor 401 and a memory 402 for storing executable instructions of the processor 401. When the processor runs the executable instructions, the focusing method of the projection lens provided by the embodiment of the invention can be realized.

The embodiment of the invention also provides a computer readable storage medium, and instructions are stored in the computer readable storage medium, so that when the instructions run on the processing component, the processing component executes the focusing method of the projection lens provided by the embodiment of the invention.

The embodiment of the present invention provides a projector, and the projector 1 may refer to the projector 1 shown in fig. 1, and as shown in fig. 1, the projector 1 includes a light valve 10, a TIR prism 20, a projection lens 30, a reflection offset lens group 40 and a driving assembly 50. The projection lens 30 may be any projection lens provided in the embodiments of the present invention. The projection lens 30 includes a first lens group 301, a second lens group 302, and a third lens group 303. The light valve 10, the TIR prism 20, the first lens group 301, the second lens group 302 and the third lens group 303 are arranged in this order. The drive assembly 50 is coupled to each lens in the second lens group 302 and is configured to control movement of each lens along the optical axis of the second lens group 302. The specific structure and the functions of each structure of the projector 1 may refer to the description of the projector 1 shown in fig. 1, and the embodiments of the present invention are not described herein.

In the projector 1 provided in the embodiment of the invention, the total length of the refraction system is L1, the distance between the refraction system and the reflection system is L2, and the distance from the light valve 10 to the first spherical lens of the first lens group 301 is the rear working distance of the projection lens 30, and because the rear working distance is approximately equal to the back focal length (back focal length, BFL), the rear working distance is also commonly referred to as BFL, wherein 0.3< BFL/L2<0.55, and 0.05< BFL/(l1+l2) <0.25, so that the ultra-short focal property of the projection lens can be satisfied. Optionally, in the projector, the offset of the light valve pixel surface with respect to the optical axis satisfies the relation 132% < offset <150%, and the light valve pixel surface refers to the plane of the light valve reflected image beam.

In addition, in the projector provided by the embodiment of the invention, in order to match with miniaturization of the projection lens, the light valve is correspondingly of a small-size model, so that the light caliber of the light valve can be reduced, and the light caliber of the lens of the projection lens can be reduced, thereby being beneficial to miniaturization of the volume of the projection lens.

Fig. 27 is a schematic diagram of the image beam direction of a projector with a frame size of 100 inches according to an embodiment of the present invention, referring to fig. 27, when the light valve 10 is illuminated, the light valve 10 outputs an image beam, and the image beam is reflected to the image offset lens set 40 after passing through the TIR prism 20. And is then transmitted through the image shift lens group 40 to the refractive system S1 of the projection lens 30. After passing through the refraction system S1, the image beam is polymerized to a certain extent, and a first imaging is performed. After the image beam after the first imaging enters the reflection system S2 of the projection lens 30, the reflection system S2 reflects the image beam out, and performs the second imaging on the screen, so that the large-size image is displayed by the screen.

Fig. 28 is a schematic diagram of an imaging optical path of a projector according to an embodiment of the invention, referring to fig. 28, the image beam is reflected to a screen 2 after being emitted from the projector 1, and a large-size image is displayed on the screen 2.

In summary, in the projector provided by the embodiment of the invention, the second lens group located in the second lens barrel includes at most three lenses, and the driving assembly can control each lens in the second lens group to move along the optical axis of the second lens group so as to change the image distance of the projection lens. The number of lenses to be controlled by the driving assembly is small, and the driving assembly does not need to control the lenses arranged at intervals to move so as to change the image distance of the projection lens, so that the focusing process is simplified.

In the present application, the terms "first," "second," "third," and "fourth," etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It is to be understood that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims (8)

1. The projection lens is characterized in that the number of lens groups in the projection lens is 3, and the projection lens comprises a first lens group, a second lens group, a third lens group, a first lens barrel, a second lens barrel and a third lens barrel;

The first lens cone, the second lens cone and the third lens cone are sequentially arranged along the light emitting direction of a light valve of a projector where the projection lens is located, the first lens group is positioned in the first lens cone, the second lens group is positioned in the second lens cone, the third lens group is positioned in the third lens cone, and the first lens group, the second lens group and the third lens group share an optical axis;

the second lens group comprises n lenses, n is more than or equal to 1 and less than or equal to 2, and the n lenses are all configured to be connected with a driving component in a projector where the n lenses are positioned and move along the optical axis of the second lens group under the control of the driving component so as to change the image distance of the projection lens;

The first lens group consists of three cemented spherical lenses with positive focal power, a third aspherical lens with positive focal power and a double cemented spherical lens with negative focal power which are sequentially arranged, the three cemented spherical lenses are far away from the second lens group, and the double cemented spherical lens is close to the second lens group;

the second lens group consists of first spherical lenses with positive focal power and second spherical lenses with negative focal power, wherein the first spherical lenses are close to the first lens group, and the second spherical lenses are close to the third lens group;

the third lens group consists of a fourteenth spherical lens with positive focal power, a fifteenth spherical lens with negative focal power and a sixteenth aspherical lens with negative focal power which are sequentially arranged, the fourteenth spherical lens is close to the second lens group, the sixteenth aspherical lens is far away from the second lens group, and the sixteenth aspherical lens is made of plastic;

the ratio of the effective focal length of the first lens group to the effective focal length of the projection lens is a, a is more than or equal to 2 and less than or equal to 12, the ratio of the effective focal length of the second lens group to the effective focal length of the projection lens is b, b is more than or equal to 20 and less than or equal to 35, the ratio of the effective focal length of the third lens group to the effective focal length of the projection lens is c, c is more than or equal to 25 and less than or equal to 35, and the effective focal length of the projection lens is d, d is more than or equal to 2.34 mm and less than or equal to 2.370 mm;

The projection ratio of the projection lens is e, and e is more than or equal to 0.23 and less than or equal to 0.24.

2. The projection lens of claim 1, wherein n = 2.

3. A focusing method of a projection lens, wherein the projection lens is a driving assembly applied to a projector, and the driving assembly is connected to n lenses in the second lens group, and the method comprises:

and controlling the n lenses to move along the optical axis of the second lens group so as to change the image distance of the projection lens.

4. A method according to claim 3, wherein the second lens group includes a first spherical lens and a second spherical lens arranged in order along the light exit direction of the light valve, and the controlling the n lenses to move along the optical axis of the second lens group includes:

When the projection lens projects to a screen and the distance between the projection lens and the screen becomes large, the first spherical lens and the second spherical lens are controlled to move along the optical axis of the second lens group in a direction away from the first lens group;

when the projection lens projects to a screen and the distance between the projection lens and the screen is reduced, the first spherical lens and the second spherical lens are controlled to move along the optical axis of the second lens group towards the direction approaching to the first lens group.

5. A focus adjustment device of a projection lens, characterized in that the focus adjustment device of the projection lens comprises respective modules for performing the focus adjustment method of a projection lens according to claim 3 or 4.

6. A focusing device of a projection lens is characterized by comprising a processor and a memory for storing executable instructions of the processor;

wherein the processor, when executing the executable instructions, is capable of implementing the method for focusing a projection lens according to claim 3 or 4.

7. A computer-readable storage medium comprising, the computer readable storage medium has instructions stored therein;

The instructions, when executed on a processing component, cause the processing component to perform the method of focusing a projection lens of claim 3 or 4.

8. A projector, comprising a driving assembly, a light valve, and the projection lens of any one of claims 1 to 2;

the light valve, the first lens group, the second lens group and the third lens group are sequentially arranged;

The drive assembly is coupled to each lens in the second lens group and is configured to control movement of each lens along an optical axis of the second lens group.