Optical system, laser projection lens and projection device

Abstract

The application discloses an optical system, a laser projection lens and a projection device. The optical system is used in cooperation with a three-color laser light source. The spectrum of the three-color laser light source is set as 455-650 nm. The optical system comprises, from an object side to an image side, a first lens with a negative focal power, a second lens with a negative focal power, a third lens with a positive focal power, a diaphragm, a fourth lens with a positive focal power, a fifth lens with a negative focal power, a sixth lens with a positive focal power, a seventh lens with a positive focal power, an equivalent prism and a photosensitive chip. When the optical system is used in a light machine system with a brightness setting of 1500 lm, light rays of the three-color laser light source are sequentially imaged on the photosensitive chip through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the equivalent prism, so as to provide an optical system which is used in cooperation with the three-color laser light source and has a better color restoration degree.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to an optical system, a laser projection lens and a projection device. BACKGROUND

[0002] In recent years, with the development of projection technology, projection lenses have been widely used in household and commercial fields, and people have higher requirements for the color and brightness of the projection picture. Therefore, more and more projectors use three-color laser light sources. The three-color laser light source projection machine system has good color restoration and high brightness, and is favored by consumers.

[0003] Because the spectrum of the three-color laser light source is relatively wide, covering the spectrum in the range of 455nm-650nm, most of the three-color laser projection lenses on the market are single-color laser lenses, which have poor color restoration. SUMMARY

[0004] The main purpose of the present application is to provide an optical system, a laser projection lens and a projection device, which are used with a three-color laser light source and have good color restoration.

[0005] To achieve the above purpose, the present application provides an optical system for use with a three-color laser light source, the spectrum of the three-color laser light source is set to cover the spectrum in the range of 455-650nm, the optical system has an object side and an image side arranged in opposite directions along the optical axis, and comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a diaphragm, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with positive focal power, an equivalent prism and a photosensitive chip arranged in sequence from the object side to the image side. The optical system is used to image the light rays of the three-color laser light source on the photosensitive chip after the light rays pass through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the equivalent prism in sequence when the light machine system has a brightness of 1500lm.

[0006] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens satisfy the following conditions with the optical system:

[0007] and and and and and

[0008] wherein, is the focal power of the first lens, a focal power of the second lens, a combined focal power of the third lens, a focal power of the fourth lens, a focal power of the fifth lens, a focal power of the sixth lens, a focal power of the seventh lens.

[0009] Optionally, the second lens and the seventh lens satisfy the following condition:

[0010] 40<|T2-T7|<55;

[0011] wherein, a focal power of the second lens, a focal power of the seventh lens, T2 is a thermal expansion coefficient of the second lens, and T7 is a thermal expansion coefficient of the seventh lens.

[0012] Optionally, a refractive index temperature coefficient dn / dt of the sixth lens is negative, and a refractive index temperature coefficient dn / dt of the seventh lens is positive.

[0013] Optionally, the first lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are made of glass.

[0014] The second lens and the seventh lens are made of plastic.

[0015] Optionally, the first lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are spherical lenses.

[0016] The second lens and the seventh lens are aspherical lenses.

[0017] Optionally, the fourth lens and the fifth lens are connected by cementing.

[0018] The application further provides a laser projection lens, which comprises an optical system.

[0019] Optionally, the laser projection lens further comprises:

[0020] a housing, wherein the optical system is arranged in the housing; and

[0021] a three-color laser light source arranged in the housing and located at one end of the optical system on the object side, wherein a spectrum of the three-color laser light source is arranged to cover a spectrum in a range of 455-650 nm.

[0022] The present invention also provides a projection device, the projection device including a laser projection lens, the laser projection lens including the optical system described above.

[0023] In the technical solution provided by this invention, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an equivalent prism, and a photosensitive chip are sequentially arranged from the object side to the image side. By setting the first lens with negative optical power, astigmatism and field curvature of large-angle light can be corrected, so that the light entering the rear group has a smaller angle and residual aberration; the second lens corrects distortion; the third lens can increase the height of the light entering the rear group, so that the system has a larger aperture; the aperture stop limits the light transmission diameter on the axis and blocks part of the light during zooming. The system features a series of lenses, including a fourth and fifth lens, which reduce light spots, improve image contrast, and enhance image quality. The fourth and fifth lenses correct chromatic aberration, making the system's aberrations compatible with a three-color laser light source. The sixth lens corrects residual chromatic aberration. The seventh lens further corrects system distortion. After passing through an equivalent prism, the system achieves high-quality imaging on the image sensor without thermal focus drift. Through the rational arrangement of the seven lenses and the conditional limitation of the optical power of each lens, an optical system with good color reproduction is provided for use with a three-color laser light source. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the optical system provided by the present invention;

[0026] Figure 2 for Figure 1 MTF curve of the optical system in the diagram;

[0027] Figure 3 for Figure 1 A point diagram of the optical system in the image.

[0028] Explanation of icon numbers:

[0029] Reference Name Reference Name 1 First lens 6 Sixth lens 2 Second lens 7 Seventh lens 3 Third lens 8 Equivalent prism 4 Fourth lens 9 Diaphragm 5 Fifth lens 10 Photosensitive chip

[0030] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0032] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0033] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously meet the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0034] At present, with the development of projection technology, projection lenses have been widely used in household and commercial fields, and people have higher requirements for the color and brightness of the projection picture. Therefore, more and more projectors use three-color laser light sources. The three-color laser light source projector system has good color restoration and high brightness, and is favored by consumers. Because the spectrum of the three-color laser light source is relatively wide, covering the spectrum in the range of 455nm-650nm, most of the three-color laser projection lenses on the market are single-color laser lenses, and the color restoration is not good.

[0035] To solve the above problems, the present application provides an optical system for use with a three-color laser light source, the spectrum of the three-color laser light source is set to cover the spectrum in the range of 455-650nm, Figures 1 to 3 The present application provides a specific embodiment of the optical system.

[0036] Please refer to Figure 1, the optical system has an object side and an image side oppositely arranged along the direction of the optical axis, comprising a first lens 1 with negative focal power, a second lens 2 with negative focal power, a third lens 3 with positive focal power, a diaphragm 9, a fourth lens 4 with positive focal power, a fifth lens 5 with negative focal power, a sixth lens 6 with positive focal power, a seventh lens 7 with positive focal power, an equivalent prism 8 and a photosensitive chip 10 arranged in sequence from the object side to the image side, and the optical system is used to image the light of the three-color laser light source on the photosensitive chip 10 through the first lens 1, the second lens 2, the third lens 3, the diaphragm 9, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the equivalent prism 8 when the light machine system is set to 1500lm.

[0037] In the technical solution provided by the present application, the first lens 1, the second lens 2, the third lens 3, the diaphragm 9, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the equivalent prism 8 and the photosensitive chip 10 are arranged in sequence from the object side to the image side, the first lens 1 with negative focal power is arranged to correct the astigmatism and field curvature of the large-angle light, so that the light entering the rear group has a smaller angle and residual aberration, the second lens 2 corrects the distortion, the third lens 3 increases the height of the light entering the rear group, so that the system has a larger aperture, the diaphragm 9 limits the on-axis beam aperture to block part of the light during zooming, reduces the light spot, improves the image contrast, and helps to improve the image quality, the fourth lens 4 and the fifth lens 5 can correct the chromatic aberration of the system, so that the aberration of the system can adapt to the three-color laser light source, the sixth lens 6 can correct the residual chromatic aberration of the system, the seventh lens 7 further corrects the distortion of the system, and after passing through the equivalent prism 8, the system finally obtains high-quality imaging on the photosensitive chip 10 without thermal focus shift. By reasonably arranging the seven lenses and conditionally limiting the focal power of each lens, an optical system is provided which is used with a three-color laser light source and has good color restoration.

[0038] Specifically, in the present embodiment, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 satisfy the following conditions with the optical system: And And And And And Wherein, F1 is the focal power of the first lens 1, F2 is the focal power of the second lens 2, F3 is the combined focal power of the third lens 3, F4 is the focal power of the fourth lens 4, the power of the fifth lens 5, the power of the sixth lens 6, the power of the seventh lens 7.

[0039] Specifically, in the embodiment, the second lens 2 and the seventh lens 7 satisfy the following conditions: 40<|T2-T7|<55; wherein, the power of the second lens 2, the power of the seventh lens 7, T2 is the thermal expansion coefficient of the second lens 2, T7 is the thermal expansion coefficient of the seventh lens 7. And the refractive index temperature coefficient dn / dt of the sixth lens 6 is negative, and the refractive index temperature coefficient dn / dt of the seventh lens 7 is positive. The projector 1500lm brightness output can be achieved without running out of focus.

[0040] Specifically, in order to improve the reliability of the lens, the optical lens system has good stability. Specifically, because the glass material has high hardness, strong wear resistance and long service life, and the all-glass lens has stable chemical properties and is not easily affected by thermal expansion and contraction to cause running out of focus, and is not easily corroded, the all-glass lens can well resist the problem of lens deformation caused by heat, and maintain the high precision of the lens for a long time. In the embodiment, the materials of the first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are glass. In this way, the optical system does not need to additionally increase the protective glass, greatly saving the cost.

[0041] In the embodiment, the materials of the second lens 2 and the seventh lens 7 are plastic. Because the plastic lens has strong impact resistance, light weight, and low cost. The most important point is that the resin lens has higher light transmittance.

[0042] Specifically, in the embodiment, the first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are spherical lenses. In this way, because the reflection of the spherical lens obeys the reflection law of light, the light rays are converged or diverged, and all spherical lenses with good processability are used, which can greatly reduce the cost and reduce the processing difficulty. Under the premise of ensuring image quality and reliability, the assembly sensitivity is low, and the yield of finished products is improved. In the embodiment, the second lens 2 and the seventh lens 7 are aspherical lenses. By using plastic aspherical lenses, the cost is effectively controlled, and the aspherical lenses can well correct the lens chromatic aberration. Under the condition of ensuring the control of the purple edge of the lens, the infrared confocal is realized, and the spherical aberration and sinusoidal difference of the high magnification position are corrected.

[0043] In summary, the lens can clearly image by reasonably distributing the optical power of the lens and considering the thermal expansion coefficient of the glass material, ensuring high yield advantage of processing and assembly, and further reducing the cost

[0044] Specifically, in order to improve the optical system quality of the optical component, reduce light energy loss, increase imaging clarity, protect the scale surface, further optimize the processing flow to meet the design requirements, reasonably use the adhesive, appropriately distribute the optical power, combine the thermal parameters of the glass material, well correct the aberration and achieve the effect of high and low temperature athermalization, and also effectively reduce the chromatic aberration to achieve the effect of clear imaging in the visible light band and near-infrared band, in the embodiment, the fourth lens 4 and the fifth lens 5 are glued and connected, which effectively corrects the chromatic aberration in the visible light band and the infrared band, and is beneficial to realize the optical system in the visible light band and the infrared light band.

[0045] It can be understood that the surface of the photosensitive chip 10 facing the object side is the imaging surface.

[0046] The optical system further comprises a filter between the equivalent prism 8 and the imaging surface, which can effectively filter out stray light in non-working wave bands to reduce light noise, reduce the difficulty of subsequent photoelectric module processing part, and thus improve the imaging quality.

[0047] Specifically, the imaging surface can be understood as the surface of the photosensitive chip 10 facing the object side, that is, the surface of the CCD or CMOS imaging element, and it can be understood that the light carrying the object information can pass through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the equivalent prism 8 in turn and finally image on the imaging surface.

[0048] Specifically, in the embodiment, the surface type, curvature radius and thickness of the lens are as shown in the following table:

[0049] Table 1

[0050] Surface number Surface type Radius / mm Thickness / mm Optical material OBJ Object plane Infinity 2000 S1 Standard Infinity 1.75 H-FK61 S2 Standard 20.374 1.21 S3 Aspherical surface 42.776 2.12 K26R S4 Aspherical surface 6.68 11.12 S5 Standard 33.519 4.95 H-ZLAF50E S6 Standard -33.519 12.565 STO Standard Infinity 9.045 S8 Standard 51.838 4.34 H-FK61 S9 Standard -9.893 1 H-ZALF53B S10 Standard -58.024 1.83 S11 Standard 45.066 3.97 H-FK61 S12 Standard -16.183 1.6 S13 Aspherical surface 82.466 2.5 D-K9 S14 Aspherical surface -31.358 6 S15 Standard Infinity 12 H-ZF52A S16 Standard Infinity 2.778 IMA Image plane Infinity -

[0051] Further, in the embodiment, the aspheric surface shape of the aspheric lens satisfies the following conditions:

[0052]

[0053] Where c is the curvature corresponding to the radius, y is the radial coordinate (its unit is the same as the lens length unit), and k is the conic quadratic coefficient (when the k coefficient is less than -1, the surface curve is a hyperbola; when the k coefficient is equal to -1, it is a parabola; when the k coefficient is between -1 and 0, it is an ellipse; when the k coefficient is equal to 0, it is a circle; and when the k coefficient is greater than 0, it is an oval). Please refer to Table 2 below. The shape and size of the aspherical surface of the object side and image side of the lens can be set by the above parameters.

[0054] Table 2 Conicity and Asphericity Coefficients for Aspherical Lenses

[0055]

[0056] Figure 2 Display the MTF curve of the optical system; Figure 3 This displays a point array (SPOT) diagram of the optical system.

[0057] As can be seen from the above figures, the spherical aberration, field curvature, and distortion of the optical system in this embodiment can all be well corrected.

[0058] In summary, the first lens 1 is a glass spherical lens, eliminating the need for additional protective glass and significantly reducing costs. The optical system achieves an output brightness of 1500 lm, is compatible with three-color laser light sources within the 455-650 nm spectral range, exhibits no chromatic aberration or thermal defocusing, and meets imaging requirements.

[0059] The present invention also provides a laser projection lens. The projection device includes the optical system described in the above technical solution. Since the projection device includes the optical system, the specific structure of the optical system is as described in the above embodiments. Since the optical system of this projection device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0060] Specifically, in this embodiment, the laser projection lens further includes a housing and a three-color laser source disposed within the housing. The optical system is housed within the housing, and the three-color laser source is located at the object-side end of the optical system. The light emitted from the three-color laser source to capture object information passes sequentially through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the equivalent prism 8, and is finally imaged onto the imaging surface. The three-color laser source is configured to cover a spectrum in the range of 455nm-650nm.

[0061] In addition, the application further provides a projection device, wherein the projection device comprises the laser projection lens according to the technical scheme, and the specific structure of the laser projection lens is referred to the above-mentioned embodiments. Since the optical system of the projection device adopts all the technical schemes of the above-mentioned embodiments, the projection device at least has all the beneficial effects brought by the technical schemes of the above-mentioned embodiments, and details are not described herein.

[0062] The above-mentioned is only the preferred embodiment of the application, and does not limit the patent scope of the application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like, which is made under the inventive concept of the application and by using the content of the application specification and drawings, is included in the patent protection scope of the application.

Claims

1. An optical system for use with a three-color laser source, wherein the spectrum of the three-color laser source is set to cover a spectrum in the range of 455-650 nm, characterized in that, The optical system has an object side and an image side arranged opposite each other along the optical axis. It includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, an aperture, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, an equivalent prism, and a photosensitive chip, arranged sequentially from the object side to the image side. The optical system is used to image the light from the three-color laser source onto the photosensitive chip after passing through the first lens, the second lens, the third lens, the aperture, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the equivalent prism in a 1500lm brightness optomechanical system. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens, together with the optical system, satisfy the following conditions: 0.02 / mm<|φ1|<0.03 / mm, and 0.06 / mm<|φ2|<0.07 / mm, and 0.03 / mm<φ3<0.05 / mm, and -0.01 / mm<φ4+φ5<-0.006 / mm, and 0.03 / mm<φ6<0.05 / mm, and 0.02 / mm<φ7<0.03 / mm; Wherein, φ1 is the optical power of the first lens, φ2 is the optical power of the second lens, φ3 is the combined optical power of the third lens, φ4 is the optical power of the fourth lens, φ5 is the optical power of the fifth lens, φ6 is the optical power of the sixth lens, and φ7 is the optical power of the seventh lens; The second lens and the seventh lens satisfy the following conditions: -4 / mm<φ2 / φ7<-2 / mm,40 / ℃ 10e+6 <|T2-T7|<55 / ℃ 10e+6 ; Wherein, φ2 is the optical power of the second lens, φ7 is the optical power of the seventh lens, T2 is the thermal expansion coefficient of the second lens, and T7 is the thermal expansion coefficient of the seventh lens.

2. The optical system as described in claim 1, characterized in that, The refractive index temperature coefficient dn / dt of the sixth lens is negative, while the refractive index temperature coefficient dn / dt of the seventh lens is positive.

3. The optical system as described in claim 1, characterized in that, The first lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all made of glass. The second lens and the seventh lens are made of plastic.

4. The optical system as claimed in claim 1, characterized in that, The first lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are spherical lenses; The second lens and the seventh lens are aspherical lenses.

5. The optical system as claimed in claim 1, characterized in that, The fourth lens and the fifth lens are glued together.

6. A laser projection lens, characterized in that, Includes the optical system as described in any one of claims 1 to 5.

7. The laser projection lens as described in claim 6, characterized in that, The laser projection lens also includes: A housing, wherein the optical system is disposed within the housing; and, A three-color laser light source is disposed inside the housing and located at the end of the optical system on the object side. The spectrum of the three-color laser light source is set to cover the range of 455-650nm.

8. A projection device, characterized in that, Includes the laser projection lens as described in any one of claims 6 and 7.

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