Projection device

Abstract

The application discloses a projection device, comprising at least one laser light source and at least one liquid crystal panel, wherein the liquid crystal panel comprises a plurality of liquid crystal pixel units arranged in an array, a light beam emitted by the laser light source passes through the at least one liquid crystal panel to form a first irradiation area and a second irradiation area, and the liquid crystal pixel units in the first irradiation area are projected to at least two liquid crystal pixel units in the second irradiation area along an optical path. The projection device can effectively inhibit the speckle phenomenon in a projection picture.

Description

Technical Field

[0001] This invention relates to the field of projection technology, and more particularly to a projection device. Background Technology

[0002] In the projection field, laser light sources are increasingly being adopted to replace LED or mercury lamp light sources due to their superior monochromaticity, resulting in high contrast and a wide color gamut. However, the narrow wavelength and strong coherence of lasers make the projected light highly susceptible to interference, leading to noticeable speckle patterns in the projected image.

[0003] Currently, the industry commonly uses the dynamic driving of diffuser vibration to solve laser projection speckle. The diffuser is used to disrupt the distribution of incident light to make the outgoing light relatively uniform. However, the microstructure size on the diffuser is difficult to further reduce, and the coherence of adjacent laser beams cannot be further disrupted, making it difficult to further suppress speckle.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a projection device that can effectively suppress speckle in the projected image.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention discloses a projection device, including at least one laser light source and at least one liquid crystal panel, wherein the liquid crystal panel includes a plurality of liquid crystal pixel units arranged in an array, the light beam emitted by the laser light source passes through at least one of the liquid crystal panels to form a first illumination area and a second illumination area, and the liquid crystal pixel units in the first illumination area are projected along the optical path onto at least two of the liquid crystal pixel units in the second illumination area.

[0008] Preferably, at least one of the liquid crystal panels includes a first liquid crystal panel and a second liquid crystal panel, wherein the light beam emitted by the laser light source passes through the first liquid crystal panel to form the first irradiation area and passes through the second liquid crystal panel to form the second irradiation area; or, the projection device further includes a reflective element disposed on one side of the liquid crystal panel, the reflective element being used to reflect the light beam passing through the first irradiation area to the second irradiation area on the same liquid crystal panel, wherein the first irradiation area and the second irradiation area do not overlap.

[0009] Preferably, the plurality of liquid crystal pixel units on the liquid crystal panel include at least two liquid crystal twist states, wherein the liquid crystal twist states of each pair of adjacent liquid crystal pixel units are different, and the liquid crystal twist states of the plurality of liquid crystal pixel units on the liquid crystal panel are periodically arranged along the direction of array arrangement.

[0010] Preferably, the projection of the liquid crystal pixel unit in the first irradiation area onto the second irradiation area along the light path has a non-integer misalignment in size between it and the liquid crystal pixel unit in the second irradiation area.

[0011] Preferably, the direction of the misalignment includes the direction of at least one side length of the liquid crystal pixel unit.

[0012] Preferably, the size of the non-integer number of liquid crystal pixel units is the size of n+1 / 2 of the liquid crystal pixel units, where n is a natural number.

[0013] Preferably, the projection of the liquid crystal pixel unit in the first irradiation area onto the second irradiation area along the light path is tilted relative to the liquid crystal pixel unit in the second irradiation area.

[0014] Preferably, the tilt angle between the projection of the liquid crystal pixel unit in the first irradiation area onto the second irradiation area along the light path and the liquid crystal pixel unit in the second irradiation area satisfies 0 < θ < 180°.

[0015] Preferably, the liquid crystal pixel unit in the first illumination region is projected along the optical path to two or four liquid crystal pixel units in the second illumination region.

[0016] Preferably, the projection device further includes a reflective element and a vibrating element. The reflective element is located on the optical path between the first irradiation area and the second irradiation area, and is used to reflect the light beam passing through the first irradiation area to the second irradiation area. The vibrating element is connected to the reflective element to cause the reflective element to vibrate.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The projection device proposed in this invention allows the laser beam emitted by the laser source to pass through the liquid crystal panel multiple times, and the projection of the liquid crystal pixel area traversed by the previous beam along the optical path is misaligned with the liquid crystal pixel area traversed by the next beam. This causes the polarization state of the light velocity in the two liquid crystal pixel areas to be spatially divided to form sub-beams with more different polarization directions. As the polarization directions between the sub-beams in adjacent areas of the laser beam become more different, the coherence between these sub-beams is weakened, the speckle size is reduced, and thus the speckle phenomenon in the projected image is effectively suppressed.

[0018] In a further proposal,

[0019] (1) The projection device may contain only one liquid crystal panel for decoherence, or it may contain two or more liquid crystal panels, and the layout can be made according to the actual situation.

[0020] (2) The projection of the liquid crystal pixel unit in the first illumination area onto the second illumination area along the optical path may have a misalignment of the size of a non-integer number of liquid crystal pixel units, or a tilt angle, or both misalignment and tilt angle may exist simultaneously, which may further weaken the coherence between the sub-beams, thereby further reducing the speckle phenomenon in the projected image.

[0021] (3) A vibrating element is set on the reflective element located between the first irradiation area and the second irradiation area, so that the position of the second irradiation area on the liquid crystal panel is constantly changed. This allows the liquid crystal pixel unit in the first irradiation area to be continuously changed in time to correspond to the liquid crystal pixel unit in the second irradiation area. Furthermore, the size of the continuous area with the same polarization state is continuously changed in time, making the interference between each beam more random. This makes it more difficult for the human eye to observe speckle. Attached Figure Description

[0022] Figure 1 This is a partial optical path diagram of the projection device according to Embodiment 1 of the present invention;

[0023] Figure 2 It is a schematic diagram showing the horizontal misalignment of the projection of the first irradiation area onto the second irradiation area;

[0024] Figure 3 yes Figure 2 A partial magnified view of the liquid crystal pixel unit in the second irradiation area;

[0025] Figure 4 yes Figure 2 A schematic diagram showing the superposition of the polarization directions of the liquid crystal pixel units in the first irradiation area and the liquid crystal pixel units in the second irradiation area.

[0026] Figure 5 It is a schematic diagram showing that the projection of the first irradiation area onto the second irradiation area is simultaneously misaligned along the horizontal and vertical directions.

[0027] Figure 6 yes Figure 5 A partial magnified view of the liquid crystal pixel unit in the second irradiation area;

[0028] Figure 7 This is a schematic diagram of the projection coverage area from the first irradiation area onto the second irradiation area.

[0029] Figure 8 yes Figure 7 A schematic diagram showing the superposition of the polarization directions of the liquid crystal pixel units in the first irradiation area and the liquid crystal pixel units in the second irradiation area.

[0030] Figure 9 It is a schematic diagram showing the tilted angle formed between the front and rear LCD panels around the light path;

[0031] Figure 10 This is a partial optical path diagram of the projection device according to Embodiment 2 of the present invention;

[0032] Figure 11 yes Figure 10 A schematic diagram of the first and second irradiation areas of the liquid crystal panel.

[0033] Figure 12 yes Figure 10 A magnified view of a portion of the LCD panel;

[0034] Figure 13 This is the optical path diagram of the projection device according to Embodiment 3 of the present invention. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0036] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0037] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] To more effectively disrupt the coherence between adjacent laser beams in a laser source and further suppress speckle in the image, this invention proposes a method that allows the laser beam to repeatedly pass through the liquid crystal panel area, and misaligns the projection of the liquid crystal pixel area traversed by the previous beam with the next liquid crystal pixel area. Thus, when there is a difference in polarization direction between adjacent liquid crystal pixel areas on the liquid crystal panel, the polarization state of the light passing through the two liquid crystal pixel areas will be spatially divided to form sub-beams with more different polarization directions. As the polarization directions of the sub-beams in adjacent areas of the laser beam become more differentiated, the coherence between these sub-beams will weaken, reducing the speckle size and thus helping to reduce speckle in the projected image.

[0040] This invention relates to projectors that employ laser light sources. These projectors can use hybrid light sources (laser + LED) or three-color laser light sources, typically red, green, and blue. In various embodiments, the laser projector proposed in this invention includes at least one laser light source, a liquid crystal panel (in this invention, a liquid crystal panel is used for decoherence), optical elements (for adjusting the propagation direction, shape, and size of the light beam, such as collimating lenses, mirrors, homogenizers, beam shapers, etc.), a spatial light modulator (generally a Digital Micromirror Device, DMD; or an LCD panel; or an Lcos (Liquid Crystal Silicon)), and a projection lens. The laser beam emitted by the laser light source, after being modulated by these components, is projected through the projection lens and forms a projected image on a screen.

[0041] A preferred embodiment of the present invention provides a projection device comprising at least one laser light source and at least one liquid crystal panel, wherein the liquid crystal panel includes a plurality of liquid crystal pixel units arranged in an array, a beam emitted from the laser light source passes through the at least one liquid crystal panel to form a first illumination region and a second illumination region, and the liquid crystal pixel units in the first illumination region are projected along the optical path onto at least two liquid crystal pixel units in the second illumination region. In a specific embodiment, the liquid crystal panel used for decoherence is located in the optical path of the laser light source, and its number can be one, two, or more.

[0042] like Figure 1The diagram shown is a partial optical path diagram of a projection device disclosed in Embodiment 1 of the present invention. It includes a laser light source 10, a collimating lens group 20, a first liquid crystal panel 31, and a second liquid crystal panel 32. In this embodiment, two identical liquid crystal panels (first liquid crystal panel 31 and second liquid crystal panel 32) are provided along the laser optical path. Each liquid crystal panel contains a large number of liquid crystal pixel units arranged in an array. Each liquid crystal pixel unit has an electrode (TFT substrate). Different voltages are applied to the electrodes to control the degree of twisting of the liquid crystal molecules in the liquid crystal pixel unit, thereby controlling the polarization direction of light passing through each liquid crystal pixel unit. For example, on a liquid crystal panel, the electrodes can control the liquid crystal pixel units to have only two liquid crystal twist states, with the liquid crystal molecules in each liquid crystal pixel unit in one liquid crystal twist state, and any two adjacent liquid crystal pixel units in the horizontal and vertical directions having different liquid crystal twist states; or, on an decoherent liquid crystal panel, the electrodes can control the liquid crystal pixel units to have three or more liquid crystal twist states, with the liquid crystal twist states of the liquid crystal pixel units arranged periodically and alternately along the arrangement direction. The liquid crystal pixel unit has a rectangular structure, with the horizontal direction being the extension direction of one side of the liquid crystal pixel unit and the vertical direction being the extension direction of adjacent sides.

[0043] Combination Figure 2 and Figure 3 The liquid crystal pixel units of the first liquid crystal panel 31 are misaligned with the liquid crystal pixel units of the second liquid crystal panel 32. That is, the projection of any liquid crystal pixel unit on the first liquid crystal panel 31 along the light path direction does not completely coincide with any liquid crystal pixel unit on the second liquid crystal panel 32, which can achieve a certain decoherence effect. Specifically, the projection area P1 of the liquid crystal pixel unit in the first irradiation area S1 (in this embodiment, the first irradiation area S1 is the coverage area on the first liquid crystal panel 31 when the light beam emitted by the laser source 10 passes through the first liquid crystal panel 31) along the light path in the second irradiation area S2 (in this embodiment, the second irradiation area S2 is the coverage area on the second liquid crystal panel 32 when the light beam emitted by the laser source 10 passes through the second liquid crystal panel 32) is misaligned with the size of a non-integer number of liquid crystal pixel units B in the second irradiation area S2. For example, the size of the non-integer number of liquid crystal pixel units is the size dk of n+1 / 2 liquid crystal pixel units, where n is a natural number.

[0044] Combination Figure 4A1, A2, and A3 are liquid crystal pixel units in the first irradiation area S1 on the first liquid crystal panel 31, and B1 and B2 are liquid crystal pixel units in the second irradiation area S2 on the second liquid crystal panel 32. Since there is a non-integer multiple of the pixel unit size dk misalignment between each liquid crystal pixel unit of the first liquid crystal panel 31 and each liquid crystal pixel unit of the second liquid crystal panel 32 in one direction, the area of ​​the largest continuous region with the same polarization direction in the laser beam will be reduced after the incident light passes through the first liquid crystal panel 31 and the second liquid crystal panel 32. Thus, the number of coherent beams in a unit area of ​​the laser beam will be reduced.

[0045] in Figure 2 and Figure 3 It only demonstrates the misalignment along the horizontal or vertical direction. For the liquid crystal pixel units in the first irradiation area S1, adjacent liquid crystal pixel units in the first irradiation area S1 have different changes in the polarization direction of the light beam, and alternate between the two polarization changes in space, for example... Figure 4 In the equations, A1 and A3 do not change the polarization direction of the incident beam, while A2 changes the polarization direction of the incident beam by 90°. (Reference) Figure 4 The light beam that originally passed through the liquid crystal pixel unit A1 in the first irradiation area S1 could only form one polarization state. However, after the light beam in this area passed through the liquid crystal pixel units B1 and B2 in the second irradiation area S2 in a misaligned manner, the light beam in this area will form two mutually perpendicular polarization states, thereby suppressing the interference between the light beams in this area.

[0046] Combination Figure 5 and Figure 6 The projection of the first irradiation area S1 onto the second irradiation area S2 can also be offset simultaneously along the horizontal and vertical directions. For example, it can be offset horizontally by the size dk of n+1 / 2 liquid crystal pixel units, and simultaneously offset vertically by the size dk of n+1 / 2 liquid crystal pixel units. In this way, we can obtain... Figure 6 and Figure 7 The diagram shows the projection coverage area, where the shaded area P2 represents the projection area of ​​liquid crystal pixel unit A5 in the first illumination area S1 into the second illumination area S2. It can be seen that this projection area spans four adjacent liquid crystal pixel units B1, B2, B3, and B4 in the second illumination area S2. Combined with... Figure 7 and Figure 8 The staggered arrangement in two directions ensures that within a unit area (e.g., the first irradiation area S1, containing liquid crystal pixel units A1 to A9)... Figure 7 The beam in the first irradiation area S1 (enclosed by the dashed box) originally had only 9 continuous polarization states. After being shifted in two directions and passing through B1 to B4 in the second irradiation area S2, it will transform into 16 continuous polarization states (e.g., ...). Figure 8As shown in the figure, the continuous region with the same polarization state within the unit range is reduced, so the beam interference phenomenon between different regions within the unit range can also be reduced accordingly.

[0047] Furthermore, such as Figure 9 As shown, in this embodiment, the two liquid crystal panels (first liquid crystal panel 31 and second liquid crystal panel 32) can also form an inclined angle around the optical path. In this way, the projection of any liquid crystal pixel unit A in the first irradiation area S1 onto the second irradiation area S2 can correspond to more liquid crystal pixel units B in the second irradiation area S2, thereby making the final polarization state of the laser beam more diverse and chaotic, suppressing the coherence of the beam. The inclined angle θ satisfies 0 < θ < 180°, for example, the inclined angle θ can be 45°.

[0048] The above embodiment is described using the example of a laser beam passing through two independent first liquid crystal panels 31 and second liquid crystal panels 32. However, in another embodiment, such as... Figures 10 to 12 This is a partial optical path diagram of the projection device disclosed in Embodiment 2 of the present invention, including a laser light source 10, a collimating lens group 20, a liquid crystal panel 30, two reflectors 40, two dichroic mirrors 50, and two LED light sources 60. In this embodiment, the laser beam emitted by the laser light source 10 can repeatedly pass through the same liquid crystal panel 30 (which is provided with multiple liquid crystal pixel units U arranged in an array) for decoherence. The liquid crystal panel 30 has a non-overlapping first illumination area S1 (in this embodiment, the first illumination area S1 is the area covered on the liquid crystal panel 30 when the laser beam emitted by the laser light source passes through the liquid crystal panel 30 for the first time) and a second illumination area S2 (in this embodiment, the second illumination area S2 is the area covered on the liquid crystal panel 30 when the laser beam emitted by the laser light source passes through the liquid crystal panel 30 for the second time). After passing through the first illumination area S1, the laser beam is reflected by the two reflectors 40 and then passes through the second illumination area S2 of the liquid crystal panel 30 again.

[0049] Figure 10 In the design of laser light source paired with LED light source, it is only necessary to let the laser light source beam pass through the LCD panel used for decoherence; the LED light source beam should not pass through it. Figure 13 The design includes three laser light sources 10, a collimating lens group 20, a liquid crystal panel 30, three reflectors 40, two dichroic mirrors 50, a spatial light modulator 70, and a projection lens 80. In this case, the laser beams of the three laser light sources 30 can all pass through the liquid crystal panel 30 used for decoherence.

[0050] Furthermore, coherence may occur between the light beams modulated by separated liquid crystal pixel units (meaning two liquid crystal pixel units separated by one liquid crystal pixel unit), making it difficult to further eliminate the interference phenomenon. Therefore, in some implementations, a vibration mechanism can be provided on the reflector 40 between the first irradiation area S1 and the second irradiation area S2, causing the reflector 40 to vibrate at high frequency along the incident and / or exit directions of the light. This continuously changes the position of the second irradiation area S2 on the decoherent liquid crystal panel, thereby continuously changing the liquid crystal pixel units in the first irradiation area S1 corresponding to those in the second irradiation area S2 in a temporal sequence. This continuously changes the size of the continuous regions with the same polarization state in a temporal sequence, making the interference between the light beams more random. This makes it more difficult for the human eye to observe speckle, thus solving the problem of the aforementioned difficulty in eliminating the interference phenomenon. The vibration mechanism can be a piezoelectric drive structure, which is driven by a high-frequency current to vibrate at high frequency.

[0051] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0052] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. A projection device, characterized in that, The system includes at least one laser source and at least one liquid crystal panel, wherein the liquid crystal panel includes a plurality of liquid crystal pixel units arranged in an array. A light beam emitted by the laser source passes through at least one of the liquid crystal panels to form a first illumination region and a second illumination region. The liquid crystal pixel units in the first illumination region are projected along the optical path onto at least two of the liquid crystal pixel units in the second illumination region. The projection of the liquid crystal pixel units in the first illumination region onto the liquid crystal pixel units in the second illumination region is tilted, such that the light beam emitted by the laser source passes through the liquid crystal panel multiple times, and the projection of the liquid crystal pixel region traversed by the previous light beam along the optical path is misaligned with the liquid crystal pixel region traversed by the next light beam. This further divides the polarization state of the light beams in the two liquid crystal pixel regions into more sub-beams with different polarization directions. As the polarization directions of the sub-beams in adjacent regions of the beam become more different, the coherence between these sub-beams is weakened, and the speckle size is reduced.

2. The projection device according to claim 1, characterized in that, At least one of the liquid crystal panels includes a first liquid crystal panel and a second liquid crystal panel. The light beam emitted by the laser light source passes through the first liquid crystal panel to form the first irradiation area and passes through the second liquid crystal panel to form the second irradiation area. Alternatively, the projection device further includes a reflective element disposed on one side of the liquid crystal panel. The reflective element is used to reflect the light beam passing through the first irradiation area to the second irradiation area on the same liquid crystal panel. The first irradiation area and the second irradiation area do not overlap.

3. The projection device according to claim 1, characterized in that, The plurality of liquid crystal pixel units on the liquid crystal panel include at least two liquid crystal twist states, wherein the liquid crystal twist states of each pair of adjacent liquid crystal pixel units are different, and the liquid crystal twist states of the plurality of liquid crystal pixel units on the liquid crystal panel are periodically arranged along the direction of array arrangement.

4. The projection device according to claim 1, characterized in that, The projection of the liquid crystal pixel unit in the first irradiation area onto the second irradiation area along the optical path has a non-integer misalignment in size between it and the liquid crystal pixel unit in the second irradiation area.

5. The projection device according to claim 4, characterized in that, The direction of the misalignment includes the direction of at least one side length of the liquid crystal pixel unit.

6. The projection device according to claim 4, characterized in that, The size of the non-integer number of liquid crystal pixel units is the size of n+1 / 2 of the liquid crystal pixel units, where n is a natural number.

7. The projection device according to claim 1, characterized in that, The tilt angle between the projection of the liquid crystal pixel unit in the first irradiation area onto the second irradiation area along the light path and the liquid crystal pixel unit in the second irradiation area satisfies 0 < θ < 180°.

8. The projection device according to claim 1, characterized in that, The liquid crystal pixel unit in the first illumination area is projected along the optical path to two or four liquid crystal pixel units in the second illumination area.

9. The projection device according to claim 1, characterized in that, It also includes a reflective element and a vibrating element. The reflective element is located on the optical path between the first irradiation area and the second irradiation area. The reflective element is used to reflect the light beam passing through the first irradiation area to the second irradiation area. The vibrating element is connected to the reflective element to make the reflective element vibrate.

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