A freeform optical system for folded projection

Abstract

The present invention discloses a free-form surface optical system for folding projection. The free-form surface optical system includes a display device, a lens group, a folding mirror, and an output mirror. The lens group focuses the light emitted by the display device onto the folding mirror, and the folding mirror folds and transmits the received light onto the output mirror. The output mirror projects the received light onto a screen, and the output mirror is a free-form surface structure. In the system of the present invention, by inserting the folding mirror between the virtual image and the output mirror, the packaging space is saved and the main optical path is shortened. Moreover, by setting the output mirror in a curved surface shape, the output image quality is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of small-space and short-distance projectors, and particularly relates to a free-form optical system for folded projection. Background Art

[0002] In existing projection technology products, concave mirror projection optical devices are used for large projection ratio image projection. However, due to the problem that concave mirror projection optical devices occupy a relatively large space, they cannot meet the requirements of product miniaturization. Therefore, there is an urgent need to design a new optical system to achieve miniaturization of the system. Summary of the Invention

[0003] The purpose of the present invention is to provide a free-form optical system for folded projection to overcome the problems of the prior art. In this system, by inserting a folded mirror between a virtual image and an output mirror, the packaging space is saved and the main optical path is shortened. Moreover, by setting the output mirror to be a curved surface, the quality of the output image is improved.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] A free-form optical system for folded projection, the free-form optical system includes a display device, a lens group, a folded mirror, and an output mirror. The lens group focuses the light emitted by the display device onto the folded mirror, and the folded mirror folds and transmits the received light onto the output mirror. The output mirror projects the received light onto a screen, and the output mirror is a free-form structure.

[0006] According to a preferred embodiment, the construction method of the free-form structure includes:

[0007] S1: Divide the object plane into n*m elemental points in the x and y directions, which are respectively V nm ; and divide the conjugate elements corresponding to the elemental points of the object plane on the image plane into I nm ;

[0008] S2: Taking the elemental points V 11 and I 11 as the foci of an ellipse, taking a point D1 on the light ray passing through the elemental point V 11 as a point on the elliptical surface, construct a first elliptical surface, and rotate the obtained elliptical surface along V 11 I 11 to obtain an ellipsoidal surface M 11 ;

[0009] S3: Taking the elemental points V 12 and I 12 as the foci of an ellipse, taking a point on the light ray passing through the elemental point V 12 and on the ellipsoidal surface M 11The intersecting point D2 is a point on the elliptical surface. A second elliptical surface is constructed and the obtained second elliptical surface is rotated along line V 12 I 12 to obtain the ellipsoidal surface M 12 ;

[0010] S4: Based on the obtained ellipsoidal surface M 11 and M 12 , the average of the two ellipsoidal surfaces M 11 and M 12 is taken to obtain the corrected surface N1;

[0011] S5: Using the element points V 13 and I 13 as the foci of the ellipse, and taking the point D3 on the ellipse surface which is on the light ray passing through the element point V 13 and intersects with the corrected surface N1. A third elliptical surface is constructed and the obtained third elliptical surface is rotated along line V 13 I 13 to obtain the ellipsoidal surface M 13 ;

[0012] S6: Based on the obtained corrected surface N1 and ellipsoidal surface M 13 , the average of the two surfaces N1 and M 13 is taken to obtain the corrected surface N2;

[0013] S7: Based on steps S5 and S6, complete the construction of the m-th elliptical surface with the element points V 1m and I 1m as the foci of the ellipse, and taking the point D 1m on the ellipse surface which is on the light ray passing through the element point V m-2 and intersects with the corrected surface N m . The obtained m-th elliptical surface is rotated along line V 1m I 1m to obtain the ellipsoidal surface M 1m ;

[0014] S8: Based on the obtained corrected surface N m-2 and ellipsoidal surface M 1m , the average of the two surfaces N m-2 and M 1m is taken to obtain the corrected surface N m-1 ;

[0015] S8: Based on the method for obtaining the corrected surface N m-1 , complete the acquisition of the associated corrected surface N 2m between V 2m and I 2m-2 until the acquisition of the associated corrected surface N nm between V nm and I nm-n is completed;

[0016] S9: Take the average of the corrected surfaces N m-1 to N nm-n to obtain the corrected surface N X , and set the distance between adjacent element points on the object surface to approach zero.

[0017] According to a preferred embodiment, the folding mirror is arranged towards the side of the display device.

[0018] According to a preferred embodiment, the folding mirror is configured to fold the light backwards to achieve the purpose of reducing the length of the optical element.

[0019] According to a preferred embodiment, the lens group is configured to form an inverted virtual image of the display device.

[0020] According to a preferred embodiment, the free-form mirror is arranged based on an elliptical surface.

[0021] According to a preferred embodiment, the display device includes, but is not limited to, using an LCOS chip.

[0022] The foregoing main solution of the present invention and its various further selection solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and claimed by the present invention; and in the present invention, (each non-conflicting selection) selections can be freely combined with each other and with other selections. Those skilled in the art can understand that there are various combinations according to the prior art and common general knowledge after understanding the solution of the present invention, all of which are the technical solutions to be protected by the present invention, and will not be enumerated here.

[0023] Advantages of the present invention: In the system of the present invention, by inserting the folding mirror between the virtual image and the output mirror, the packaging space is saved and the main optical path is shortened. And, by setting the output mirror in a curved shape, the quality of the output image is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the principle structure of the free-form optical system of the present invention;

[0025] Figure 2 is a schematic diagram of the reflection principle of the output mirror in the free-form optical system of the present invention;

[0026] Figure 3 is a schematic diagram of the construction of the free-form surface of the output mirror in the free-form optical system of the present invention;

[0027] Figure 4 is a schematic diagram of the construction of the free-form surface of the output mirror in the free-form optical system of the present invention;

[0028] Figure 5It is a schematic diagram for constructing the free-form surface of the output mirror in the free-form surface optical system of the present invention;

[0029] Figure 6 It is a schematic diagram for constructing the free-form surface of the output mirror in the free-form surface optical system of the present invention;

[0030] Figure 7 It is a schematic diagram for constructing the free-form surface of the output mirror in the free-form surface optical system of the present invention;

[0031] Among them, 101 - display device, 102 - lens group, 103 - folding mirror, 104 - output mirror, 105 - screen, 200 - object surface, 300 - image plane. Specific embodiments

[0032] The following uses specific specific examples to illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] It should be noted that, to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0036] In addition, the present invention should be noted that in the present invention, if the specific structures, connection relationships, position relationships, power source relationships, etc. involved are not specifically written, the structures, connection relationships, position relationships, power source relationships, etc. involved in the present invention are all known to those skilled in the art on the basis of the prior art without creative efforts.

[0037] Example 1:

[0038] Reference Figure 1 As shown, a free-form optical system for folded projection is shown in the figure. The free-form optical system includes a display device, a lens group, a folding mirror, and an output mirror.

[0039] Preferably, the lens group focuses the light emitted by the display device onto the folding mirror, and the folding mirror folds and transmits the received light onto the output mirror, and the output mirror projects the received light onto the screen.

[0040] Preferably, the display device includes, but is not limited to, an LCOS chip.

[0041] Preferably, the lens group is configured to form an inverted virtual image of the display device and project the light onto the folding mirror.

[0042] Preferably, the folding mirror is disposed towards the side of the display device.

[0043] Further, the folding mirror is configured to fold the light backward to achieve the purpose of reducing the length of the optical element.

[0044] Preferably, the output mirror is a free-form structure. Further, the free form can be set based on an elliptical surface.

[0045] Specifically, referring to FIGS. 2 to Figure 7 As shown. The object plane 200 is divided into n*m elements in the x and y directions. Each element is represented as Vnm. Starting from V 11 , this element has a coupled element I on the image plane 300 11 . Calculate each mirror surface Mnm, and obtain the free-form surface N from each mirror surface Mnm X . The object plane 200 can represent the folding mirror 103, and the image plane 300 can represent the screen 105.

[0046] Preferably, it is assumed that there are only 9 element points on the object surface, V 11 , V 12 , V 13 , V 21 , V 22 , V 23 , V 31 , V 32 , V 33 . For the 3 element points V in the vertical direction 11 , V 12 , V 13 and the corresponding coupled elements I on the image plane 11 , I 12, I 13 is taken as an example to construct a free-form surface. Among them, the spatial positions of points V 11 , V 12 , V13 , I 11 , I 12 , I 13 are known. In addition, the position of the light source point irradiating the object surface is known.

[0047] Refer to Figure 3 and Figure 4 as shown. Taking the element points V 11 and I 11 as the foci of the ellipse. Taking a point D1 on the light ray passing through the element point V 11 as a point on the ellipse surface. The distance from the point D1 to the point V 11 is set to a value between 5 - 20 cm. Specifically, the position of the D1 point is set based on the installation space between the output mirror 104 and the folding mirror 103 in the optical system. Among them, the light source position irradiating the element point V 11 is known, so that the light ray passing through the element point V 11 can be uniquely confirmed, that is, the point D1 can be uniquely obtained.

[0048] Thus, by taking the element points V 11 and I 11 as the foci of the ellipse and taking the point D1 as a point on the ellipse, the construction of the ellipse surface is realized, and the obtained ellipse surface is rotated along the line V 11 I 11 to obtain the ellipsoidal surface M 11 . Through the shape setting of this ellipsoidal surface M 11 , the light ray passing through the point V 11 , after being reflected by the ellipsoidal surface M 11 , will surely pass through the point I 11 .

[0049] Refer to Figure 4 as shown. Taking the element points V 12 and I 12 as the foci of the ellipse. Taking a point D2 on the light ray passing through the element point V 12 as a point on the ellipse surface. The point D2 is the intersection point of the light ray passing through the point V 12 and the ellipsoidal surface M 11 .

[0050] Thus, by taking the element points V 12 and I 12 as the foci of the ellipse and taking the point D2 as a point on the ellipse, the construction of the ellipse surface is realized, and the obtained ellipse surface is rotated along the line V 12 I 12 to obtain the ellipsoidal surface M 12 .

[0051] As Figure 5 shown, based on the obtained ellipsoidal surface M 11 and M 12 , the two ellipsoidal surfaces M 11 and M 12 are averaged to obtain the corrected surface N1.

[0052] As Figure 6 shown, taking the element points V 13 and I 13 as the foci of the ellipse. Taking a point D3 on the light ray passing through the element point V 13 as a point on the elliptical surface, and the point D3 is the intersection point of the light ray passing through the point V 13 and the corrected surface N1.

[0053] Thus, by taking the element points V 12 and I 12 as the foci of the ellipse and the point D3 as a point on the ellipse, the construction of the elliptical surface is realized, and the obtained elliptical surface is rotated along the line V 13 I 13 to obtain the ellipsoidal surface M 13 .

[0054] As Figure 7 shown, based on the obtained corrected surface N1 and the ellipsoidal surface M 13 , the two surfaces N1 and M 13 are averaged to obtain the corrected surface N2. That is, the corrected surface N2 constructs a correlation surface related to the object surface element points V 11 , V 12 , V 13 and the image plane element points I 11 , I 12 , I 13 . When the spacing or step size between the points V 11 , V 12 , V 13 is small enough or approaches zero, the corrected surface N2 is a free surface.

[0055] Based on the method for obtaining the corrected surface N2, a corrected surface N4 related to the object surface element points V 21 , V 22 , V 23 and the image plane element points I 21 , I 22 , I 23 is constructed. Based on the method for obtaining the corrected surface N2, a corrected surface N2 related to the object surface element points V 31 , V 32 , V 33 and the image plane element points I 31 , I 32 , I33 The corrected surface N6. By averaging the corrected surfaces N2, N4, and N6, the corrected surface N that correlates the object surface 200 and the image plane 300 can be obtained X , and when the spacing between the respective element points on the object surface is small enough, the corrected surface N X is a free-form surface structure.

[0056] In the system of the present invention, by inserting a folding mirror between the virtual image and the output mirror, the packaging space is saved and the main optical path is shortened. Moreover, by setting the output mirror to be curved, the quality of the output image is improved.

[0057] The basic example of the present invention and its various further alternative examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed by the present invention. In the solution of the present invention, each alternative example can be arbitrarily combined with any basic example and alternative example.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A freeform optical system for folded projection, characterized in that, The free-form surface optical system includes a display device, a lens group, a folding mirror, and an output mirror. The lens group focuses the light emitted by the display device onto the folding mirror, and the folding mirror folds and transmits the received light onto the output mirror, and the output mirror projects the received light onto the screen. Moreover, the output mirror is of a free-form surface structure. The construction method of the free-form surface structure includes: S1: Divide the object surface into n*m elemental points in the x and y directions, which are respectively V nm ; and divide the coupling elements corresponding to the elemental points of the object surface on the image plane into I nm ; S2: With the element point V 11 and I 11 as the foci of the ellipse, and taking a point D1 on the light ray passing through the element point V 11 as a point on the elliptical surface, construct the first elliptical surface, and rotate the obtained elliptical surface along V 11 I 11 to obtain the ellipsoidal surface M 11 ; S3: With the element points V 12 and I 12 as the foci of the ellipse, taking the point D2 which passes through the element point V 12 on the light ray and intersects with the ellipsoidal surface M 11 as a point on the elliptical surface, constructing a second elliptical surface, and rotating the obtained second elliptical surface along the line V 12 I 12 to obtain the ellipsoidal surface M 12 ; S4: Based on the obtained ellipsoidal surface M 11 and M 12 , take the average of the two ellipsoidal surfaces M 11 and M 12 to obtain the corrected surface N1; S5: With the element points V 13 and I 13 as the foci of the ellipse, and with the point D3 on the light ray passing through the element point V 13 and intersecting the correction surface N1 as a point on the elliptical surface, construct a third elliptical surface, and rotate the obtained third elliptical surface along the line V 13 I 13 to obtain the ellipsoidal surface M 13 ; S6: Based on the obtained corrected surface N1 and the ellipsoidal surface M 13 , take the average of the two surfaces N1 and M 13 to obtain the corrected surface N2; S7: Based on steps S5 and S6, complete the construction of an ellipse with element points V 1m and I 1m as the foci, with a point D 1m on the ray passing through element point V m-2 and intersecting the correction surface N m as a point on the ellipse surface, construct the m-th elliptical surface, and rotate the obtained m-th elliptical surface along line V 1m I 1m to obtain the ellipsoidal surface M 1m ; S8: Based on the obtained corrected surface N m-2 and the ellipsoidal surface M 1m , average the two surfaces N m-2 and M 1m to obtain the corrected surface N m-1 ; S8: Based on the acquisition method of the modified surface N m-1 , complete the acquisition of the associated modified surface N 2m of V 2m and I 2m-2 , until the acquisition of the associated modified surface N nm of V nm and I nm-n is completed; S9: Take the average of the corrected surfaces N m-1 to N nm-n obtained in step S8 to obtain the corrected surface N X , and set the spacing between adjacent element points on the object surface to approach zero.

2. The freeform optical system according to claim 1, wherein The folding mirror is arranged on the side of the display device.

3. The free-form optical system according to claim 2, wherein The folding mirror is configured to fold the light backward.

4. The free-form optical system according to claim 1, wherein The lens group is configured to form an inverted virtual image of the display device.

5. The free-form optical system according to claim 1, wherein The display device includes, but is not limited to, an LCOS chip.

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