Speckle-eliminating projection structure for improving laser projection color contrast by using double DMDs (Digital Micromirror Device)

Abstract

The utility model discloses a double-DMD (Digital Micromirror Device) speckle-eliminating projection structure for improving laser projection color contrast, which comprises a light source device, a beam combining system, a dodging speckle-eliminating system, DMDs, a DMD time sequence control device and a projection output lens which are sequentially arranged along the light propagation direction, and a piezoelectric vibration table for applying vibration to the DMDs is also arranged on the DMDs; the light source device is used for emitting laser in various colors to the beam combining system; the beam combining system is used for spatially combining the lasers with multiple colors to form a single light beam; and the light uniformizing and spot eliminating system is used for enabling the combined light beams to output a light field with uniform intensity. The two DMDs are adopted for simultaneous control, so that the problem that the contrast ratio is reduced due to the fact that a single DMD is not turned over in time can be avoided; the piezoelectric vibration table can randomly change the optical path of the output image, so that different speckle patterns are formed on the screen, the speckle patterns of each frame are different, and the speckle contrast ratio is reduced by using the average effect of human eyes.

Description

Technical Field

[0001] The utility model relates to the technical field of laser projection, in particular to a speckle-eliminating projection structure for improving the color contrast of laser projection with a dual DMD. Background Art

[0002] As an advanced display device, laser projectors utilize a high-contrast ratio, a key metric for measuring image clarity and detail. This contrast ratio directly impacts the viewer's visual experience, especially in applications requiring high color accuracy and brightness.

[0003] Traditional laser projectors typically use a single digital micromirror device (DMD) to project images. DMD is an advanced display technology that uses an array of micromirrors to reflect light onto the projection screen, generating images by controlling the flip state of the micromirrors. However, while single DMD projectors perform well in achieving deep blacks, at high brightness settings, diffraction occurs due to the close proximity of the DMD's micromirror array spacing to the laser wavelength. This causes light energy to disperse, reducing the center brightness of the projected image and, in turn, affecting its maximum brightness, resulting in reduced contrast in the laser projector's color performance.

[0004] To improve the color contrast and speckle reduction of laser projectors, the industry has made various attempts. For example, projectors using a dual DMD structure, by cascading two DMDs, can improve image brightness and contrast to a certain extent. However, this structure also has some issues, such as reduced contrast caused by the untimely flipping of a single DMD micromirror, and laser speckle.

[0005] Laser speckle, caused by the coherence of laser light, creates a granular pattern of alternating light and dark on the projection screen, reducing image clarity and visual quality. Various methods have been proposed to eliminate speckle, such as using diffusers to shift the laser's phase or using specific filters to filter out some diffracted light. However, while these methods eliminate speckle, they can also negatively impact image brightness and contrast.

[0006] Therefore, the industry urgently needs a projection device that can not only improve the color contrast of laser projectors but also effectively eliminate speckles to meet the growing demand for high-quality displays. Utility Model Content

[0007] The purpose of the present invention is to solve the problems of the above-mentioned background technology and to propose a speckle-eliminating projection structure with dual DMDs for improving the color contrast of laser projection.

[0008] The purpose of the utility model can be achieved through the following technical solutions:

[0009] A dual-DMD speckle reduction projection structure for improving the color contrast of laser projection includes a light source device, a beam combining system, a uniform speckle reduction system, a DMD, a DMD timing control device, and a projection output lens, which are sequentially arranged along the light propagation direction. The DMD is also provided with a piezoelectric vibration table for applying vibration to the DMD.

[0010] The light source device is used to emit lasers of multiple colors to the beam combining system;

[0011] The beam combining system is used to spatially combine lasers of multiple colors to form a single beam;

[0012] The light uniforming and speckle elimination system is used to make the combined light beam output a light field with uniform intensity and preliminarily suppress laser speckle;

[0013] The DMD is used to preliminarily modulate the light field and adjust the light field;

[0014] The DMD timing control device is used to control the flip state of the DMD;

[0015] The projection output lens is used to project the light field modulated by the DMD into an image.

[0016] As a further solution of the present invention: the light source device includes three lasers of different colors.

[0017] As a further solution of the present invention: there are two DMDs, the first DMD outputs light to the second DMD, the first DMD is used to preliminarily modulate the light field, and the second DMD is used to further adjust the light field.

[0018] As a further solution of the present invention: the piezoelectric vibration table specifically applies vibration to the first DMD.

[0019] As a further solution of the present invention: the three different colors in the light source device are red, green and blue.

[0020] Beneficial effects of the utility model:

[0021] (1) Using two DMDs to control simultaneously can avoid the problem of contrast reduction caused by the untimely flipping of a single DMD micromirror;

[0022] (2) The piezoelectric vibration table will randomly change the optical path of the output image, thereby forming different speckle patterns on the screen, resulting in a different speckle pattern for each frame, and using the averaging effect of the human eye to achieve a reduction in speckle contrast. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 It is a structural diagram of the present utility model.

[0025] In the figure: 1. Light source device; 2. Beam combining system; 3. Light uniformity and speckle reduction system; 4. Piezoelectric vibration table; 5. DMD; 6. DMD timing control device; 7. Projection output lens. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] For example 1, please refer to Figure 1 As shown, the utility model is a dual DMD speckle reduction projection structure for improving the color contrast of laser projection, comprising a light source device 1, a beam combining system 2, a uniform light speckle reduction system 3, a DMD 5, a DMD timing control device 6, and a projection output lens 7, which are sequentially arranged along the light propagation direction. The DMD 5 is also provided with a piezoelectric vibration table 4 for applying vibration to it.

[0028] The light source device 1 is used to emit lasers of multiple colors to the beam combining system 2;

[0029] Beam combining system 2, used to spatially combine multiple colors of laser light into a single beam;

[0030] The light uniforming and speckle elimination system 3 is used to make the output of the combined light beam have a uniform intensity and to preliminarily suppress the laser speckle;

[0031] DMD5, used for preliminary modulation and adjustment of the light field;

[0032] DMD timing control device 6, used to control the flip state of DMD5;

[0033] The projection output lens 7 is used to project the light field modulated by the DMD 5 into an image.

[0034] For example 2, please refer to Figure 1 As shown, the utility model is a dual DMD speckle reduction projection structure for improving the color contrast of laser projection, comprising a light source device 1, a beam combining system 2, a uniform light speckle reduction system 3, a DMD 5, a DMD timing control device 6, and a projection output lens 7, which are sequentially arranged along the light propagation direction. The DMD 5 is also provided with a piezoelectric vibration table 4 for applying vibration to it.

[0035] The light source device 1 is used to emit lasers of multiple colors to the beam combining system 2. The light source device 1 includes three lasers of different colors. The three different colors in the light source device 1 are red, green, and blue.

[0036] Beam combining system 2, used to spatially combine multiple colors of laser light into a single beam;

[0037] The light uniforming and speckle elimination system 3 is used to make the output of the combined light beam have a uniform intensity and to preliminarily suppress the laser speckle;

[0038] DMD5 is used for preliminary modulation of the light field and adjustment of the light field. There are two DMD5s. The first DMD5 outputs light to the second DMD5. The first DMD5 is used for preliminary modulation of the light field, and the second DMD5 is used for further adjustment of the light field.

[0039] The piezoelectric vibration table 4 specifically applies vibration to the first DMD 5;

[0040] DMD timing control device 6, used to control the flip state of DMD5;

[0041] The projection output lens 7 is used to project the light field modulated by the DMD 5 into an image.

[0042] The working principle of this utility model:.

[0043] The overall structure consists of three light source devices 1, a beam combining system 2, a light uniforming and speckle elimination system 3, a piezoelectric vibration table 4, a dual DMD 5, a DMD timing control device 6 and a projection output lens 7.

[0044] After being emitted by light source device 1, the red, green, and blue laser beams are spatially combined by beam combining system 2, allowing them to output a light field at the same spatial location. After passing through uniform light and speckle reduction system 3, the beams are uniformly intensity-conserving, preliminarily suppressing laser speckle and reducing the diffraction effect of DMD 5, thereby fully utilizing the laser output. The uniform light output by system 3 first illuminates the first DMD 5, achieving a preliminary cluster output. After reflection, it illuminates the second DMD 5, further adjusting the output light field, and ultimately outputting an image through projection lens 7.

[0045] During operation of the overall projection system, the DMD timing control device 6 controls the inversion of the two DMDs 5. The tilt angle, switching speed, and mirror reflectivity of the DMD 5 micromirrors directly affect contrast. The greater the switching speed and tilt angle of the micromirrors, the better the light isolation between the "on" and "off" states, and the higher the contrast. Simultaneously controlling the two DMDs 5 avoids the contrast reduction caused by delayed micromirror inversion in a single DMD 5.

[0046] The piezoelectric vibration table 4 continuously applies random left and right vibrations to the first DMD 5, while the second DMD 5 maintains its position. This does not affect the position of the output image, but can also apply different phase distributions to the output image in a short period of time. The time integration method is used to further reduce the speckle contrast and achieve speckle suppression on the output image.

[0047] The above describes one embodiment of the present invention in detail. However, the content is merely a preferred embodiment of the present invention and should not be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the claims of the present invention.

Claims

1. A dual DMD speckle-eliminating projection structure for improving the color contrast of laser projection, characterized in that: The system comprises a light source device (1), a beam combining system (2), a uniform light speckle elimination system (3), a DMD (5), a DMD timing control device (6), and a projection output lens (7) which are sequentially arranged along the light propagation direction; the DMD (5) is also provided with a piezoelectric vibration table (4) for applying vibration thereto; The light source device (1) is used to emit laser light of multiple colors to the beam combining system (2); The beam combining system (2) is used to spatially combine lasers of multiple colors to form a single beam; The light uniforming and speckle elimination system (3) is used to make the combined light beam output a light field with uniform intensity and preliminarily suppress laser speckle; The DMD (5) is used to preliminarily modulate the light field and adjust the light field; The DMD timing control device (6) is used to control the flip state of the DMD (5); The projection output lens (7) is used to project the light field modulated by the DMD (5) into an image.

2. The dual DMD speckle-eliminating projection structure for improving color contrast in laser projection according to claim 1, characterized in that: The light source device (1) comprises three lasers of different colors.

3. The dual DMD speckle-eliminating projection structure for improving color contrast in laser projection according to claim 1, characterized in that: There are two DMDs (5), the first DMD (5) outputs light to the second DMD (5), the first DMD (5) is used for preliminarily modulating the light field, and the second DMD (5) is used for further adjusting the light field.

4. The dual DMD speckle-eliminating projection structure for improving color contrast in laser projection according to claim 3, characterized in that: The piezoelectric vibration table (4) specifically applies vibration to the first DMD (5).

5. The dual DMD speckle-eliminating projection structure for improving color contrast in laser projection according to claim 1, characterized in that: The three different colors in the light source device (1) are red, green and blue.

Images