Projection device for improving grating image projection distortion

Abstract

The invention provides a projection device for improving grating image projection distortion, which comprises a laser point light source, a magnifying lens, a beam expander and a distortion-removing grating sheet for removing the projection distortion of a grating image, and is characterized in that divergent light t1 emitted by the laser point light source is changed into parallel light t2 after passing through the beam expander; the parallel light rays light t2 are changed into light rays light 3 emitted at a field angle theta after passing through the distortion-removing grating sheet, and the light rays light 3 continue to pass through the magnifying lens and then are projected to a target projection area to form an ideal grating orthogonal grid image; from the perspective of hardware, the grating image is a target standard image when being imaged on a plane through the distortion-removing grating sheet, so that the purpose of removing the projection distortion of the grating image is achieved, the distortion does not need to be removed by an image processing algorithm, the subsequent image processing steps are simplified, and the processing efficiency is improved. And hardware platform development resources and software operation cost are saved. And meanwhile, the stability of projection distortion improvement is improved.

Description

Technical Field

[0001] The invention relates to a projection device for improving grating image projection distortion, belonging to the technical field of grating image projection. Background Art

[0002] The grating image is generated by the grating generator, and is applied to various scenarios to realize the function of object perception by relying on its image characteristics. The principle of its generation is that a point light source passes through the grating sheet to generate a grating grid in a small area, and the grid is enlarged according to the detection area requirements by using the principle of lens magnification. The grating image projection screen of the grating generator is affected by the installation position of the grating generator and the lens. The shape of the grid projection screen may be barrel-shaped, trapezoidal, or the superposition of barrel-shaped and trapezoidal.

[0003] At present, conventional grating generators include laser point light sources, grating plates, and magnifying lenses. The grating plate is an optical element based on the theory of light wave diffraction. When light passes through the grating, the light wave will bend and scatter. The grating can redirect and shape the light wave to produce a grating pattern. The grating image produced after the light passes through the grating plate has a limited coverage area. The magnifying lens magnifies the grating image projection area to reach the target projection area size. The grating image projection effect of the entire grating generator is as follows: Figure 1 As shown in (a), from Figure 1 In (a), it can be clearly seen that the entire grating image has a large projection distortion and the distortion type is not unique. The closer to the edge of the image, the more severe the distortion.

[0004] In order to obtain an ideal grating image, the current approach is usually to use image processing algorithms to correct the images captured by the camera from a software perspective. However, the above-mentioned image processing method places certain requirements on both the hardware platform and the software algorithm, and the correction effect is difficult to guarantee. Therefore, a simple, effective, and stable projection device for improving grating grid projection distortion is urgently needed.

[0005] The above problems are issues that should be considered and resolved in the projection process of improving grating image projection distortion. Summary of the invention

[0006] The purpose of the present invention is to provide a projection device for improving grating image projection distortion to solve the problem in the prior art that the software algorithm used to correct projection distortion is complex and has poor stability.

[0007] The technical solution of the present invention is:

[0008] A projection device for improving projection distortion of a grating image comprises a laser point light source and a magnifying lens, a beam expander and a de-distortion grating sheet for removing projection distortion of the grating image. The divergent light light1 emitted by the laser point light source is transformed into parallel light light2 after passing through the beam expander. The parallel light light2 is transformed into light light light3 emitted at a field angle θ after passing through the de-distortion grating sheet. The light light3 is further projected onto a target projection area after passing through the magnifying lens to form an ideal grating orthogonal grid image.

[0009] Furthermore, the dedistorted grating sheet includes a grating sheet engraved with an anti-distorted grating line image, and the anti-distorted grating line image is obtained by a method based on a reverse light path and using a film-sensitive film for exposure and then development.

[0010] Furthermore, the anti-distortion ruled line image includes a plurality of cross-arranged transverse anti-distortion ruled lines and longitudinal anti-distortion ruled lines, and the curvatures of the transverse anti-distortion ruled lines and longitudinal anti-distortion ruled lines increase from the middle to both ends.

[0011] Furthermore, the anti-distortion ruled line image is obtained by using an anti-distortion image generating device.

[0012] Furthermore, the anti-distortion image generating device includes an ideal grating grid image, a focus-adjustable lens group, a film-sensitive film and a shielding object for shielding the film-sensitive film. The ideal grating grid image is arranged in the target projection area, and the focus-adjustable lens group is arranged between the ideal grating grid image and the film-sensitive film.

[0013] Furthermore, the ideal raster grid image adopts a rectangular grid in a checkerboard format.

[0014] Furthermore, the ideal grating grid image is made of a self-luminous light material.

[0015] Furthermore, the process of obtaining the dedistorted grating sheet is as follows:

[0016] First, an ideal grating grid image is arranged in the target projection area, and then the relative position relationship between the magnifying lens and the target projection area in the application scenario is simulated. With the arranged ideal grating grid image as a reference, the adjustable focus lens group is arranged and fixed at the original position of the magnifying lens, that is, the target projection area and the magnifying lens are replaced by the ideal grating grid image and the adjustable focus lens group, respectively. The focal length of the adjustable focus lens group is set to f, and the distance L between the ideal grating grid image and the adjustable focus lens group is 1 Satisfy f<L 1 <2f;

[0017] Then, referring to the relative position relationship between the magnifying lens and the de-distortion grating sheet in the grating projector, the blocked film is arranged and fixed on the original position of the de-distortion grating sheet based on the fixed adjustable focus lens group; according to the lens imaging law, the distance L between the blocked film and the adjustable focus lens group is 2 With L 1 The relationship between , f satisfies 1 / f=1 / L 2 +1 / L 1 , thus through L 1 and f to obtain L 2 ;

[0018] Adjust the ambient light intensity to make it lower than the set value, and then remove the obstruction on the film;

[0019] At this time, the propagation path of the light is a reverse light path opposite to the propagation path of the light when the grating is projected in the actual application scenario, which is an ideal grating image-adjustable focus lens group-film-sensitive film, and finally forms an anti-distortion line image on the film-sensitive film.

[0020] The beneficial effect of the present invention is that: compared with the prior art, the projection device for improving the projection distortion of grating images, from the perspective of hardware, by dedistorting the grating sheet, makes the grating image a target standard image when imaging on the plane of the target projection area, thereby achieving the purpose of removing the projection distortion of the grating image, and does not need to rely on image processing algorithms to remove the distortion, thus simplifying the subsequent image processing steps, saving hardware platform development resources and software operation costs. At the same time, the distortion improvement effect achieved by improving the hardware is hardly affected by reasons other than hardware damage, thereby improving the stability of the projection distortion improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagrams illustrating the existing grating projection effect and the ideal grating grid image, wherein (a) is a schematic diagram illustrating the existing grating projection effect, and (b) is a schematic diagram illustrating the ideal grating grid image;

[0022] Figure 2 It is a schematic structural diagram of a projection device for improving grating image projection distortion according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram for explaining the acquisition of an anti-distortion scribed line image on a dedistortion grating sheet in an embodiment;

[0024] Figure 4 Schematic diagrams for explaining an existing grating sheet and a de-distorted grating sheet, wherein (a) is a schematic diagram of an existing grating sheet, and (b) is a schematic diagram of a de-distorted grating sheet;

[0025] Figure 5is a schematic diagram illustrating the effect of using a grating image to improve projection distortion in an embodiment;

[0026] Wherein: 1- laser point light source, 2- beam expander, 3- dedistortion grating, 4- magnifying lens, 5- anti-distortion ruled line image, 6- target projection area, 7- adjustable focus lens group, 8- film sensitive film;

[0027] 51- transverse anti-distortion markings, 52- longitudinal anti-distortion markings. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the drawings in specific embodiments. It should be pointed out that the technical solution and design principle of the present invention are described in detail below only with an optimized technical solution, but the protection scope of the present invention is not limited to this.

[0029] A projection device for improving projection distortion of grating images, such as Figure 2 , including a laser point light source 1 and a magnifying lens 4, including a beam expander 2 and a de-distortion grating plate 3 for removing projection distortion of a grating image. The divergent light light1 emitted by the laser point light source 1 is transformed into a parallel light light2 after passing through the beam expander 2. The parallel light light2 is transformed into a light light3 emitted at a field angle θ after passing through the de-distortion grating plate 3. The light light3 continues to pass through the magnifying lens 4 and is projected onto a target projection area 6 to form an ideal grating orthogonal grid image.

[0030] Compared with the prior art, the projection device for improving the projection distortion of grating images of the present invention, starting from the hardware perspective, by dedistorting the grating sheet 3, makes the grating image an ideal grating grid image when imaging on the plane, thereby achieving the purpose of removing the projection distortion of the grating image, and does not need to rely on image processing algorithms to remove the distortion, thus simplifying the subsequent image processing steps, saving hardware platform development resources and software operation costs. At the same time, the distortion improvement effect achieved by improving the hardware is hardly affected by reasons other than hardware damage, thereby improving the stability of the projection distortion improvement.

[0031] In the projection device for improving projection distortion of grating images, the dedistorted grating sheet 3 includes a grating sheet engraved with an anti-distortion scribed line image 5, which is obtained by exposing and then developing a film photosensitive film 8 based on a reverse light path. The anti-distortion scribed line image 5 is obtained by an anti-distortion image generating device.

[0032] like Figure 3The anti-distortion image generating device includes an ideal grating grid image, a focus-adjustable lens group 7, a film-sensitive film 8, and a shielding object for shielding the film-sensitive film 8. The ideal grating grid image is set in the target projection area 6, and the focus-adjustable lens group 7 is set between the ideal grating grid image and the film-sensitive film 8. The ideal grating grid image adopts a rectangular grid in a chessboard format. The material for making the ideal grating grid image adopts a self-luminous light material.

[0033] like Figure 3 The acquisition process of the dedistorted grating sheet 3 is to first arrange the following in the target projection area 6: Figure 1 The ideal grating grid image shown in (b) is then used to simulate the relative position relationship between the magnifying lens 4 and the target projection area 6 in the application scenario. The arranged ideal grating grid image is used as a reference, and the adjustable focus lens group 7 is arranged and fixed at the original position of the magnifying lens 4, that is, the ideal grating grid image and the adjustable focus lens group 7 are used to replace the target projection area 6 and the magnifying lens 4 respectively, and the focal length of the adjustable focus lens group 7 is set to f. Then, the distance L between the ideal grating grid image and the adjustable focus lens group 7 is 1 Satisfy f<L 1 <2f; referring to the relative position relationship between the magnifying lens 4 and the de-distortion grating sheet 3 in the grating projector, based on the fixed adjustable focus lens group 7, the blocked film photosensitive film 8 is arranged and fixed at the original position of the de-distortion grating sheet 3; according to the lens imaging law, the distance L between the blocked film photosensitive film and the adjustable focus lens group 2 With L 1 The relationship between , f satisfies 1 / f=1 / L 2 +1 / L 1 , thus through L 1 and f to obtain L 2 ; Adjust the ambient light intensity so that the ambient light intensity is lower than the set value such as 0W to keep the environment dim, and remove the obstructions on the film-sensitive film 8; at this time, the propagation path of the light is the ideal grating image-adjustable focus lens group 7-film-sensitive film 8. At this time, the propagation path of the light is opposite to the propagation path of the light when the grating is projected in the actual application scenario, which is the ideal grating image-adjustable focus lens group 7-film-sensitive film 8, and finally an anti-distortion image 5 is formed on the film-sensitive film 8, such as Figure 4 (b), the anti-distortion ruled line image 5 is engraved on the grating sheet to obtain the dedistorted grating sheet 3. The anti-distortion ruled line image 5 includes a plurality of cross-arranged transverse anti-distortion ruled lines 51 and longitudinal anti-distortion ruled lines 52, and the curvatures of the transverse anti-distortion ruled lines 51 and longitudinal anti-distortion ruled lines 52 are both increased from the middle to the two ends.

[0034] Figure 3 1 is a schematic diagram for explaining the acquisition of the anti-distortion ruled line image 5 on the dedistortion grating sheet 3 in the embodiment. Figure 3 The purpose of the implementation process of the reverse light path is to obtain Figure 1 The anti-distortion ruled line image 5 on the dedistorted grating sheet 3 is formed to achieve the purpose of forming an ideal orthogonal rectangular grating grid image after the parallel light ray light2 passes through the dedistorted grating sheet 3 during the normal grating projection process. The field angle of the light after passing through the magnifying lens 4 is φ, and φ is much larger than θ.

[0035] This projection device for improving the projection distortion of a grating image improves the grating sheet that forms the grating image based on the idea of ​​a reverse light path, and obtains an anti-distortion line image 5 on the grating sheet by exposing and then developing a film-sensitive film 8, which can reduce the distortion of the projected grating image. The device can be used in object perception to better perceive the object and improve the accuracy of perception.

[0036] The projection device for improving grating image projection distortion can be used for visual detection of obstacle contours. By removing grating image projection distortion, the speed and accuracy of visual detection of obstacle contours can be effectively improved, and the adaptability of visual detection to the environment is enhanced. The device has low cost, high accuracy and is easy to use, and is suitable for the field of vehicle visual detection technology.

[0037] The above embodiments are preferred implementation modes of the present invention and are intended to explain the present invention. The present invention is not limited to the above embodiments. Any obvious modification, replacement or variation that can be made by those skilled in the art without departing from the essential content of the present invention shall fall within the protection scope of the present invention.

Claims

1. A projection device for improving grating image projection distortion, comprising a laser point light source and a magnifying lens, Features: It includes a beam expander and a de-distortion grating plate for removing projection distortion of a grating image. The divergent light light1 emitted by a laser point light source is transformed into a parallel light light2 after passing through the beam expander. The parallel light light2 is transformed into a light light light3 emitted at a field angle θ after passing through the de-distortion grating plate. The light light3 continues to pass through a magnifying lens and is projected onto a target projection area to form an ideal grating orthogonal grid image.

2. The projection device for improving grating image projection distortion as claimed in claim 1, Features: The dedistorted grating sheet comprises a grating sheet engraved with an anti-distorted grating line image, and the anti-distorted grating line image is obtained by a method of exposing and then developing a film-sensitive film based on a reverse light path.

3. The projection device for improving grating image projection distortion as claimed in claim 1, Features: The anti-distortion scribed line image includes a plurality of cross-arranged transverse anti-distortion scribed lines and longitudinal anti-distortion scribed lines, and the curvatures of the transverse anti-distortion scribed lines and longitudinal anti-distortion scribed lines increase from the middle to both ends.

4. The projection device for improving grating image projection distortion as claimed in claim 1, Features: The anti-distortion ruled line image is obtained by using an anti-distortion image generating device.

5. The projection device for improving grating image projection distortion as claimed in claim 4, Features: The anti-distortion image generating device comprises an ideal grating grid image, a focus-adjustable lens group, a film-sensitive film and a shielding object for shielding the film-sensitive film. The ideal grating grid image is arranged in a target projection area, and the focus-adjustable lens group is arranged between the ideal grating grid image and the film-sensitive film.

6. The projection device for improving grating image projection distortion as claimed in claim 5, Features: An ideal raster grid image uses a rectangular grid in the form of a checkerboard.

7. The projection device for improving grating image projection distortion according to claim 5 or 6, Features: The ideal raster grid image is made using a self-luminous light material.

8. The projection device for improving grating image projection distortion as claimed in claim 7, Features: The process of obtaining the dedistorted grating is as follows: First, an ideal grating grid image is arranged in the target projection area, and then the relative position relationship between the magnifying lens and the target projection area in the application scenario is simulated. With the arranged ideal grating grid image as a reference, the adjustable focus lens group is arranged and fixed at the original position of the magnifying lens, that is, the target projection area and the magnifying lens are replaced by the ideal grating grid image and the adjustable focus lens group, respectively. The focal length of the adjustable focus lens group is set to f, and the distance L between the ideal grating grid image and the adjustable focus lens group is 1 Satisfy f<L 1 <2f; Then, referring to the relative position relationship between the magnifying lens and the de-distortion grating sheet in the grating projector, the blocked film is arranged and fixed on the original position of the de-distortion grating sheet based on the fixed adjustable focus lens group; according to the lens imaging law, the distance L between the blocked film and the adjustable focus lens group is 2 With L 1 The relationship between , f satisfies 1 / f=1 / L 2 +1 / L 1 , thus through L 1 and f to obtain L 2 ; Adjust the ambient light intensity to make it lower than the set value, and then remove the obstruction on the film; At this time, the propagation path of the light is a reverse light path opposite to the propagation path of the light when the grating is projected in the actual application scenario, which is an ideal grating image-adjustable focus lens group-film-sensitive film, and finally forms an anti-distortion line image on the film-sensitive film.

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