A laser projection display method and system

Abstract

This invention discloses a laser projection display method and system. The method involves configuring the micromirrors of a phase-modulated light device into a high-low periodic structure. Then, based on optical diffraction characteristics, the actual height of the phase-modulated light device under each stage of driving signals is measured. Next, an ideal height set for the micromirrors is defined, which changes linearly with the progressively increasing driving signals. The actual heights that are within a defined error range from the actual heights are identified. These actual heights are matched with the phase level to establish an approximately linear relationship between the driving signal and the changeable phase level. This allows the driving signal to be sent according to the desired linearized height distribution in subsequent designs, achieving an approximately linear adjustment relationship between the change in the actual micromirror position and the change in the ideal micromirror position, thereby improving the dynamic contrast adjustment effect.

Description

Technical Field

[0001] This invention belongs to the field of laser projection technology, specifically, it relates to a laser projection display method and system. Background Technology

[0002] In the display field, dynamic contrast ratio was first applied to projectors (dynamic aperture control) and LCD TVs to reduce the brightness of blacks in dim scenes or increase the maximum brightness in a scene, thereby improving the visual experience.

[0003] The core component of a Digital Light Processing (DLP) projector is the Digital Micromirror Device (DMD). The DMD contains millions of independently controlled micromirrors (built on corresponding CMOS memory units). During operation, the DMD controller loads a "1" or a "0" into each basic memory unit, causing each micromirror to switch between +12° and -12° states. The +12° state corresponds to an "on" pixel, and the -12° state corresponds to an "off" pixel. In applications, grayscale graphics are created by programming the on / off duty cycle of each mirror, and multiple light sources can be multiplexed to create RGB full-color images.

[0004] To improve the dynamic contrast of DLP projection systems, early methods primarily focused on adjusting the laser source power or reducing the light transmittance in darker areas of the projected image. For example, in the published invention CN 105578162, a black field processing module calculates the luminance histogram of the projected image, and then an ARM processor averages the luminance histogram. The required current for the laser source is then calculated using a lookup table method or a linear correspondence method, thereby optimizing the dynamic contrast of the projected image. For example, in the published invention CN 210465982, it is pointed out that when the DMD micromirror is in the "off" state, a small amount of light will still hit the DMD micromirror and enter the lens after reflection. This results in the brightness of dark images projected by the DLP projection system still being relatively high. Therefore, based on the original DLP projection system structure, a TIR prism, a control unit, and an LCD contrast unit are added. The control unit calculates the color and grayscale of each pixel in the projected image, thereby adjusting the voltage of the corresponding area on the LCD contrast unit and controlling the emission degree of the corresponding three primary color rays, thereby reducing or blocking the light transmission rate of darker areas of the projected image and improving the contrast of the DLP projection system.

[0005] In recent years, schemes to enhance dynamic contrast through phase modulation have emerged. For example, in the published invention CN114153119, a dimming device is used to modulate the phase of light, dividing the image into different dimming areas. After the light is modulated by the dimming device, the light in different dimming areas can be enhanced or attenuated, thereby achieving high dynamic contrast. However, due to the limitations of the dimming device manufacturing process, there is a difference between the actual change in the micromirror position and the ideal change in the micromirror position under the action of the driving signal that adjusts the micromirror position, resulting in an unsatisfactory adjustment effect on dynamic contrast. Summary of the Invention

[0006] This invention proposes a laser projection display method and system. Starting from the optical path, the phase of light is modulated by a phase light modulator, which can reduce the brightness of darker areas and increase the brightness of brighter parts of the image. At the same time, the relationship between the driving signal that drives the micromirror position change of the phase light modulator and the adjustment phase is remapped, so that the position change of the micromirror under the action of the remapped driving signal is close to the ideal position, thereby achieving more precise dimming.

[0007] The present invention is implemented using the following technical solutions:

[0008] A laser projection display method is proposed, comprising:

[0009] The micromirrors of the phase light modulator are configured with a high-low periodic structure; where low corresponds to the height of the micromirrors of the phase light modulator under the lowest level driving signal, and high corresponds to the height of the micromirrors of the phase light modulator under other levels of driving signals besides the lowest level driving signal.

[0010] Based on the optical path difference of the beam under the high and low periodic structure, the actual height of the micromirror under each level of driving signal except the lowest level driving signal is calculated;

[0011] Find the micromirror height where the actual height and the ideal height are within a specified error range; where the ideal height is a set of micromirror heights that increase linearly with the driving signal.

[0012] The relationship between the driving signal and its changed phase level is established based on the driving signal corresponding to the found micromirror height.

[0013] The height of the micromirror in the phase-modulated light device is modulated by the relationship between the driving signal and its changed phase level.

[0014] A laser projection display system is proposed, comprising:

[0015] A light source, used to provide a beam of light;

[0016] A phase-modulated light device for adjusting the phase of at least one beam of light in an illumination beam provided by a light source;

[0017] DMD chips are used to modulate the illumination beam after it has been dimmed by a phase spatial light modulator.

[0018] A projection lens is used to project and image the beam modulated by the DMD chip.

[0019] The micromirror structure setting unit is used to set the micromirrors of the phase light modulation device into a high-low periodic structure; wherein, low corresponds to the height of the micromirrors of the phase light modulation device under the lowest level driving signal, and high corresponds to the height of the micromirrors of the phase light modulation device under other levels of driving signals besides the lowest level driving signal;

[0020] The actual height measurement unit of the micromirror is used to calculate the actual height of the micromirror under each level of driving signal except the lowest level driving signal, based on the optical path difference of the beam under the high and low periodic structure.

[0021] The mapping unit is used to find the micromirror height where the actual height and the ideal height are within a defined error range. Based on the driving signal corresponding to the found micromirror height, a relationship between the driving signal and its changed phase level is established, so that the phase light modulation device can modulate the height of the micromirror according to the relationship between the driving signal and its changed phase level. The ideal height is a set of micromirror heights that increase linearly with the driving signal.

[0022] Compared with existing technologies, the advantages and positive effects of this invention are as follows: In the laser projection display method and system proposed in this invention, the micromirrors of the phase light modulation device are set as a high-low periodic structure. The low position corresponds to the height of the micromirrors under the lowest-level driving signal, and the high position corresponds to the height of the micromirrors under each level of driving signal (excluding the lowest-level driving signal). Then, based on optical diffraction characteristics, the actual heights of the phase light modulation device under each level of driving signal are measured. Next, an ideal height set for the micromirrors is set. This ideal height set changes linearly with the progressively increasing driving signal. The actual heights within a limited error range that match the ideal heights are identified from the actual heights. These actual heights are matched with the phase level to establish an approximately linear relationship between the driving signal and the changeable phase level. This allows the driving signal to be sent according to the desired linearized height distribution in subsequent designs, achieving an approximately linear adjustment relationship between the change in the actual micromirror position and the change in the ideal micromirror position, thereby improving the dynamic contrast adjustment effect.

[0023] In some embodiments of the present invention, the GS algorithm is used to calculate the phase distribution of the image brightness distribution on the phase mask surface of the phase light modulation device. This can be combined with the above-mentioned approximately linear adjustment relationship to obtain the corresponding driving signal to adjust the position of the micromirror, thereby obtaining the expected brightness distribution in the DMD chip.

[0024] In some embodiments of the present invention, the subframe trigger signal of the phase light modulator is designed to be synchronized with the subframe trigger signal of the DMD chip, so that the subframe of the phase light modulator is aligned with the subframe of the DMD chip, and the light beam modulated by the phase light modulator is used as the backlight of the subframe, so that the backlight effect of the displayed image is better and the subjective visual experience is improved.

[0025] Other features and advantages of the present invention will become clearer after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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 these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the laser projection display system proposed in this invention;

[0028] Figure 2 This is a schematic diagram of the phase light modulation device in the laser projection display system proposed in this invention;

[0029] Figure 3 This is a schematic diagram of the driving electrode and common electrode structure of a single micromirror in the phase light modulation device of the laser projection display system proposed in this invention;

[0030] Figure 4 This is a schematic diagram of the micromirror position structure of the phase light modulation device in the laser projection display system proposed in this invention;

[0031] Figure 5 The nonlinear relationship between the driving signal of an existing phase-modulated optical device and its changing phase level is presented as the driving signal is increased step by step in a stepped manner.

[0032] Figure 6 The linear relationship between the driving signal of an ideal phase-modulated optical device and its changing phase level is presented when the driving signal is increased stepwise in a stepwise manner.

[0033] Figure 7 This diagram illustrates the execution steps of the laser projection display method proposed in this invention.

[0034] Figure 8 This is a schematic diagram of the height structure of the micromirrors in the laser projection display method proposed in this invention;

[0035] Figure 9This is a schematic diagram illustrating the calculation of the actual height of the micromirrors in the laser projection display method proposed in this invention;

[0036] Figure 10 This is a schematic diagram illustrating the calculation of the actual height of the micromirrors in the laser projection display method proposed in this invention;

[0037] Figure 11 This is a schematic diagram illustrating the process of calculating the horizontal phase distribution of the light beam in the phase-modulated device using the GS algorithm in this invention;

[0038] Figure 12 The control timing sequence of the laser projection display system proposed in this invention;

[0039] Figure 13 This is a schematic diagram of the system structure of the laser projection display system proposed in this invention;

[0040] Figure 14 This is a schematic diagram of the composition of the mirror height and phase mapping adjustment module in this invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., 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 this 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 this invention.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0044] 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 this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] like Figure 1 As shown, the laser projection system proposed in this invention includes:

[0046] Light source 100 is used to provide an illumination beam. In this embodiment of the invention, it is a laser light source. The shaped beam of the laser light source is directed towards the phase light modulation device 200. The laser light source includes a red light source, a blue light source, and a green light source. These three light sources can emit light simultaneously or in a set sequence.

[0047] A phase-modulated light device 200 is used to adjust the phase of at least one beam of light in the illumination beam provided by the light source 100, so as to change the light intensity of at least one beam of light in the illumination beam after being dimmed by the phase-modulated light device 200. Based on this, the difference in brightness between image zones corresponding to at least two beams of light in the projected image can be amplified, thereby improving the dynamic contrast of the projected image. Here, dynamic contrast refers to the ratio of brightness between the brightest and darkest parts of the projected image.

[0048] The DMD chip 300 modulates the illumination beam after it has been dimmed by the phase light modulator 200, and the modulated illumination beam is then directed toward the projection lens 400. Specifically, the projected image is divided into R, G, and B component sub-images according to the three primary colors R, G, and B. The control circuit of the projection system converts the signal of each color component sub-image into a corresponding drive signal, so that the DMD chip 300 modulates the beam of light incident upon it. In this invention, the modulation is applied to the beam of light with a change in intensity distribution after it has been dimmed by the phase light modulator 200.

[0049] The projection lens 400 is used to project the illumination beam modulated by the DMD chip 300 into an image and display it on the projection screen 500.

[0050] like Figure 2 As shown, the phase light modulation device 200 has a light reflecting surface, which is composed of multiple dimming units. Each dimming unit includes a micromirror 201 and its driving component 202. The driving component 202 is used to change the position of the micromirror 201 in the vertical direction of the light reflecting surface. When the positions of the multiple micromirrors in the vertical direction of the light reflecting surface are different, the entire light reflecting surface can exhibit a structure with local concavity and local convexity, such as... Figure 3 As shown.

[0051] Based on this structure, when an illumination beam is directed toward its light-reflecting surface, the different micromirrors, due to their different positions, can result in different optical path lengths and phases of the light rays reflected by the micromirrors.

[0052] Therefore, when the phase light modulator 200 drives multiple dimming units to be positioned differently in the direction of the light reflecting surface, the phase of the light beam reflected by each dimming unit will be different. This will cause coherent interference or destructive interference between the light beams reflected by each dimming unit, and thus the light intensity of the light beam after dimming by the phase light modulator 200 will also be different.

[0053] Specifically, because the positions of each dimming unit vertically upward on the light reflecting surface are not exactly the same, the entire light reflecting surface presents a non-planar structure. This non-planar structure includes both concave and convex structures. The concave structure forms a concave reflector, which makes the light beam converge and coherent interference between different light beams can increase the brightness of the corresponding light beam area. The convex structure forms a convex reflector, which makes the light beam diverge and coherent interference between different light beams or directing them to other areas, thereby reducing the brightness of the relative light beam area and increasing the brightness of its adjacent light beam area.

[0054] Therefore, in actual design, the projected image can be divided into multiple image partitions, which correspond to multiple dimming partitions of the phase light modulator 200. The multiple dimming partitions of the phase light modulator 200 correspond one-to-one with multiple light beams, forming a correspondence between image partitions, dimming partitions, and light beam partitions.

[0055] Each dimming zone of the phase light modulation device 200 includes several dimming units. When two adjacent dimming zones present different light reflection surface shapes based on the function of their dimming units, the two adjacent dimming zones can implement different optical path changes on the light beam, thereby achieving different phase modulations and ultimately changing the brightness, i.e., light intensity, of the two dimming zones. In this way, the contrast of the two image zones corresponding to the two adjacent dimming zones can also be changed.

[0056] In summary, the phase light modulator 200 can dim the illumination beam provided by the light source 100 based on the image information of the projected image, so that the light intensity of each beam in the illumination beam after dimming by the phase light modulator 200 is not the same. Based on this, the brightness difference of different areas in the projected image can be amplified. Without changing the luminous brightness of the light source 100 and without processing the projected image, the dynamic contrast of the projected image can be improved, thereby improving the display effect of the projected image projected through the projection lens 400.

[0057] The phase light modulator 200 needs to acquire the brightness information of the projected image. Then, by adjusting the position of the micromirrors in each dimming unit, the brightness of the beam partition corresponding to the image partition with higher brightness is increased after dimming by the phase light modulator 200, and the brightness of the beam partition corresponding to the image partition with lower brightness is decreased after dimming by the phase light modulator 200. This makes the image partition with higher brightness brighter and the image partition with lower brightness darker.

[0058] When the phase light modulation device 200 drives the dimming unit to change the position of its micromirror in the vertical direction of the light reflecting surface, it obtains its brightness information based on image information, generates a driving signal based on the brightness information, and adjusts the position of the dimming unit according to different driving signals, thereby achieving the adjustment of different phases of the light beam.

[0059] As can be seen from the existing publicly available technology, the dimming unit consists of a micromirror and its driving component. The driving component consists of several driving electrodes and a common electrode, with gaps between each driving electrode. The position of the micromirror is adjusted by applying 0V or 10V to each driving electrode: when a voltage of 0V is applied to the driving electrode, the voltage difference between the driving electrode and the common electrode is negative, there is no electro-adhesion between them, and the position of the micromirror in the vertical direction of the light reflecting surface does not change; when a voltage of 10V is applied to the driving electrode, a positive voltage difference is formed between the driving electrode and the common electrode, which generates an electro-adhesion between them, and the position of the micromirror in the vertical direction of the light reflecting surface is changed under the action of this electro-adhesion.

[0060] The magnitude of the electro-adsorption force is related to the area of ​​the driving electrode. The larger the area of ​​the driving electrode to which the voltage is applied, the greater the electro-adsorption force. Therefore, by setting different driving electrodes or different combinations thereof to 10V, multiple positional changes of the micromirror can be achieved, thereby realizing multiple phase order changes.

[0061] Theoretically, the more driving electrodes there are, the more positions the micromirrors can change, and the more precise the beam phase modulation within the dimming zone.

[0062] The following table shows the mapping relationship between a phase-modulated optical device 200 and the driving signal for a changeable phase level of the light beam (corresponding to the position of a micromirror):

[0063] Table 1

[0064]

[0065]

[0066] As shown in Table 1, in the embodiments, a dimming unit includes four driving electrodes (denoted as A, B, C, and D). By combining different driving electrodes, the phase light modulator 200 can adjust sixteen phase levels, that is, adjust the micromirror at sixteen positions. For example, when driving electrodes A, B, C, and D are loaded with a voltage of 0 volts, the micromirror is adjusted to position L0, and the phase light modulator 200 can change the phase level of the beam at level 0. When driving electrode A is loaded with a voltage of V volts and the other driving electrodes are loaded with a voltage of 0 volts, the micromirror is adjusted to position L1, and the phase light modulator 200 can change the phase level of the beam at level 1.

[0067] As mentioned earlier, the magnitude of the electro-adhesion force between the driving electrode and the common electrode is related to the area of ​​the driving electrode. However, due to limitations in the fabrication process, it is difficult to design each driving electrode in the phase-modulated light device 200 to have the same area. This results in different electro-adhesion forces between each driving electrode and the common electrode after the applied voltage. Consequently, the actual change in the micromirror position under different driving signals differs from the ideal value, causing the final phase level of the beam change to not conform to the ideal phase level. This exhibits a non-linear relationship between the driving signal and the phase level it changes as the driving signal increases stepwise. Figure 4 As shown, this results in a less than ideal adjustment effect for dynamic contrast; such as Figure 5 The figure shows the ideal phase level of beam adjustment when the driving signal is increased stepwise, demonstrating an ideal linear relationship between the driving signal and the changed phase level as the driving signal is increased stepwise.

[0068] In order to improve the adjustment accuracy of dynamic contrast, the present invention uses optical diffraction characteristics to remap the driving signal of the phase light modulation device 200 to the changeable phase level, so that the two are close to a linear relationship to achieve a more accurate dimming effect.

[0069] Based on the above ideas, this invention utilizes the characteristics of optical diffraction to measure the actual height of the micromirrors generated by the phase light modulator 200 under the drive of various driving signals by changing the micromirror structure of the phase light modulator 200. Then, the actual height and phase level are matched to establish an approximately linear relationship between the driving signal and the changeable phase level. This ensures that the driving signal and the changed phase level are approximately linearly related when the driving signal is increased step by step. As a result, the driving signal can be sent according to the desired linearized height distribution in subsequent designs.

[0070] Specifically, the present invention is achieved through the following means, such as... Figure 6 As shown, it includes:

[0071] S61: Set the micromirrors of the eye position light modulation device to a high-low periodicity structure.

[0072] Among them, the height of the micromirror of the low-level phase-modulated light device under the lowest-level driving signal, and the height of the micromirror of the high-level phase-modulated light device under other driving signals besides the lowest-level driving signal.

[0073] A schematic diagram of high and low periodic structures is shown below. Figure 7 As shown.

[0074] Taking the embodiment shown in Table 1 as an example, for the 15 levels of driving signals other than the lowest level driving signal, a high-low periodic structure is set for each level, and the actual height of the micromirror under the driving of each level of driving signal is obtained in step S62.

[0075] S62: Based on the optical path difference of the beam under high and low periodic structures, calculate the actual height of the micromirror under all levels of driving signals except the lowest level driving signal.

[0076] like Figure 8 and Figure 9 As shown, the height of the micromirror is represented by h, and the width of the micromirror is represented by d. The optical path difference of the beam under the high and low structures can be expressed by the following formula:

[0077]

[0078] When the bright fringe condition Δ=mλ(m=0,±1,±2......)(2) is met, the receiving screen will display a bright fringe.

[0079] The first distance D between the receiving screen and the phase light modulator, and the second distance L between the bright fringe and the zeroth-order bright fringe (taking the first-order bright fringe as an example) are measured, where the angle... When m = 1, by combining equations (1) and (2), where the width d of the micromirror is known, the actual height h of the micromirror at this time can be calculated.

[0080] Following the embodiment shown in Table 1 above, the actual heights h1, h2, h3, ..., h15 of the 15 micromirrors are calculated by driving them with 15 levels of driving signals (with a high-low periodic structure set under each level of driving signal).

[0081] S63: Find the micromirror height where the actual height and the ideal height are within the specified error range.

[0082] Taking the example shown in Table 1, after calculating the actual height of the micromirror under the other 15 driving signals (excluding the lowest driving signal), the height of the micromirror that is within the limit error range of the ideal height is found from the actual heights of these 15 micromirrors.

[0083] The ideal height is a set of micromirror heights that change linearly with the step-by-step increase of the drive signal, as shown in Table 2 below as an example:

[0084] Table 2

[0085]

[0086]

[0087] Driven by progressively increasing driving signals (0, 1, 2, 3, 4, 5, 6, 7), the ideal height set of the micromirror is defined as 0 / 1 / 8, 2 / 8, 3 / 8, 4 / 8, 5 / 8, 6 / 8, and 7 / 8 of the height driven by the highest-level driving signal. The actual heights of the micromirror measured under progressively increasing driving signals are 0 / 16, 2 / 16, 3 / 16, 2 / 8, 4 / 8, 5 / 8, and 7 / 8. To achieve the desired height... For near-linear mapping, the mapping series is usually reduced from the existing driving signal series. For example, if three driving signals 0, 1, and 2 are defined, the ideal height of the micromirror would be 0, 4 / 8, and 7 / 8 respectively. Based on the concept of this invention, it is necessary to find the actual heights 0, 4 / 8, and 7 / 8 that are within the limited error range of 4 / 8 and 7 / 8 respectively from the actual heights 0, 1 / 16, 2 / 16, 3 / 16, 2 / 8, 4 / 8, 5 / 8, and 7 / 8 (assuming the limited error range is 0).

[0088] S64: Establish the relationship between the driving signal and its changed phase level based on the driving signal corresponding to the found micromirror height.

[0089] The driving signals at the actual heights found and their changed phase levels are remapped. That is, the driving signal 000 is mapped to the 0th level phase level, the driving signal 110 is mapped to the 2nd level phase level, and the driving signal 111 is mapped to the 3rd level phase level, forming a phase level relationship that changes approximately linearly with the driving signal increasing step by step.

[0090] In some embodiments of the present invention, the relationship between the progressively increasing driving signal and its changing phase level is remapped by determining the ideal height of the micromirror with a set step size, including:

[0091] 1. Determine the ideal height of the intermediate stage of the microscope using a step size of half, and find the actual height that is within the specified error range of the ideal height of the intermediate stage.

[0092] For example, taking the highest actual height of the micromirror as 1, and based on the original drive signal having 16 levels, the ideal height of the intermediate level of the micromirror is set to 0.5 with a step size of half, and the actual height that is within the limited error range of 0.5 is found from 15 actual heights.

[0093] 2. Determine the secondary ideal height of the micromirror using a quarter step size, and find the actual height that is within the specified error range from the secondary ideal height.

[0094] With the highest actual height of the micromirror as 1, and based on the original drive signal having 16 levels, the secondary ideal height of the micromirror is set to 0.25, 0.5, and 0.75 in a quarter step. From the remaining 14 actual heights, the actual heights that are within the specified error range of 0.25 and 0.75 are found respectively.

[0095] 3. Determine the ideal height of the microscope in steps of one-eighths, and find the actual height that is within the limit error range of the ideal height.

[0096] With the highest actual height of the micromirror as 1, and based on the original drive signal having 16 levels, the ideal heights of the three levels of the micromirror are set to 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, and 0.875 with a step size of one-eighth. From the remaining 12 actual heights, the actual heights that are within the specified error range of 0.125, 0.375, 0.625, and 0.875 are found.

[0097] 4. Determine the fourth-order ideal height of the microscope using a step size of one-sixteenth, and find the actual height that is within the limit error range of the fourth-order ideal height.

[0098] Taking the highest actual height of the micromirror as 1, and based on the original drive signal having 16 levels, the ideal heights of the three levels of the micromirror are set to 0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.375, 0.4375, 0.5, 0.5625, 0.625, 0.6875, 0.75, 0.8125, 0.875, and 0.9375 in a step size of one-sixteenth. From the remaining 8 actual heights, the actual heights that are within the specified error range of 0.0625, 0.1875, 0.3125, 0.4375, 0.5625, 0.6875, 0.8125, and 0.9375 are selected.

[0099] 5. In the above steps, if the actual height and the ideal height cannot meet the limit error range under a certain set step size, then return to the actual height found in the previous step and end the search.

[0100] 6. Use the actual height found according to the set step size method to remap the relationship between the driving signal that is gradually increased step by step and its changed phase level.

[0101] S65: The height of the micromirror of the phase light modulator is modulated by the relationship between the driving signal and its changed phase level.

[0102] After remapping, the relationship between the driving signal and its changed phase level approaches a linear one. The smaller the limit error range, the closer the approximate linear relationship is to the ideal linear relationship. When the limit error range is zero, the remapped driving signal and its changed phase level exhibit an ideal linear relationship. Under the action of the corresponding driving signal, the total area of ​​the driving electrode with applied voltage increases approximately linearly, thereby changing the electro-adhesion force between it and the common electrode in an approximately linear relationship. This makes the difference between the change in the micromirror position under the action of the driving signal and the ideal value approach zero, ultimately making the phase level of the beam change approach the ideal phase level. This demonstrates that as the driving signal is increased stepwise, the relationship between it and its changed phase level is approximately linear, thus improving the adjustment accuracy of dynamic contrast.

[0103] As mentioned above, when the phase light modulator 200 drives the dimming unit to change the position of its micromirror in the vertical direction of the light reflecting surface, it obtains the brightness information based on the image information and generates the driving signal based on the brightness information. That is, it is necessary to know the brightness information of each image partition before it can determine which image partitions need to increase brightness and which image partitions need to decrease brightness. Then it can determine which dimming partitions of the phase light modulator 200 need to enhance the brightness of the corresponding beam partitions and which dimming partitions need to attenuate the brightness of the corresponding beam partitions. In this way, the dynamic contrast of the image can be improved by making the brighter areas brighter and the darker areas darker.

[0104] In this embodiment of the invention, a grayscale image of the projected image is used to obtain brightness information, and then the phase that the phase modulation device needs to adjust is calculated.

[0105] First, this invention obtains the brightness information of the projected image by converting the RGB image to grayscale. Since each pixel includes red, blue, and green sub-pixels, in order to easily determine the grayscale value of each pixel, i.e., the brightness information, it is necessary to comprehensively consider the grayscale values ​​of the three components, R, G, and B. This can be achieved using the following method:

[0106] 1. Maximum value method; that is, compare the values ​​of the R, G, and B components of the transmission image, and take the component with the largest gray level:

[0107] Gray = max(R, G, B).

[0108] 2. Average value method: Calculate the arithmetic mean of the sum of the R, G, and B components; the gray level is equal to the average of the three components.

[0109]

[0110] 3. Weighted average method: Assign different weights to the R, G, and B components, and then calculate the weighted average. The weights are assigned based on the importance of the three components or other indicators.

[0111]

[0112] 4. Luminosity Method: In the YUV color space, the physical meaning of the Y component is the brightness of the pixel; therefore, the Y component can represent a grayscale image.

[0113] Y = 0.3R + 0.5G + 0.11B.

[0114] After obtaining the grayscale image of the projected image through any of the above methods, the brightness of each image partition can be obtained by statistical analysis or division using existing methods.

[0115] After determining the brightness information of each image partition, it is necessary to know the phase distribution of the brightness of the image partition on the phase mask surface of the phase light modulator 200 in order to obtain its corresponding amplitude on the imaging surface of the DMD chip 300. However, the amplitude on the imaging surface of the DMD chip 300 is a known quantity, while the phase distribution on the phase mask surface of the phase light modulator 200 is an unknown quantity. It is necessary to determine the phase distribution that the phase light modulator 200 needs to adjust through phase recovery. Among these methods, the Gerchberg-Saxton algorithm (hereinafter referred to as the GS algorithm) is the most representative.

[0116] The GS algorithm in this embodiment of the invention uses the known amplitude Ai of the Imaging surface of the DMD chip to solve for the unknown Phase mask surface φp at the Phase light modulator, including:

[0117] First of all, with This represents the amplitude and phase of the illumination beam at various positions on the Phase mask surface of the phase light modulator, where (x, y) represents the position of the dimming unit in the phase light modulator 200, and Ap(x, y) represents the amplitude distribution of the illumination beam on the Phase mask surface of the phase light modulator 200. This represents the phase distribution of the illumination beam on the phase mask surface of the phase light modulator 200.

[0118] Next, with This represents the amplitude and phase of the illumination beam at various positions on the imaging surface of the DMD chip, where (x, y) represents the position of the dimming unit in the phase light modulator 200, and Ai(x, y) represents the amplitude distribution of the illumination beam on the imaging surface of the DMD chip after dimming by the phase light modulator 200. This indicates the phase distribution of the illumination beam on the Imaging surface of the DMD chip after being dimmed by the phase light modulator 200.

[0119] Finally, the phase distribution that the phase modulation device 200 needs to adjust is determined using the GS algorithm according to the following steps, such as... Figure 10 As shown:

[0120] S1: Will The initial amplitude Ap is set to 1, and the initial phase φp is random.

[0121] S2: Based on the diffraction formula, obtain the phase φi and amplitude distribution Ai of the imaging surface of the DMD chip, retain only the phase information of the imaging surface, and set the amplitude to the amplitude of the target image.

[0122] S3: Based on the inverse diffraction formula, obtain the amplitude Ap and phase φp of the returned Phase mask surface; then set the amplitude Ap of the Phase mask surface to 1, and retain the phase information φp.

[0123] Repeat steps S2 and S3 until the error limit is met or the maximum number of iterations is reached to obtain the phase φp of the phase mask surface, which is the phase distribution that the phase light modulation device 200 needs to adjust.

[0124] After obtaining the phase distribution that needs to be adjusted in the phase light modulator 200, the corresponding driving signal can be obtained by combining the mapping relationship shown in Table 2 above. The obtained driving signal is used to drive the height of the phase light modulator micromirror so as to obtain the expected brightness distribution in the DMD chip.

[0125] In some embodiments of the present invention, such as Figure 11 As shown, a frame trigger signal and a subframe trigger signal for a phase-light modulator are designed. The frame trigger signal is synchronized with the frame trigger signal of the DMD chip, and the subframe trigger signal is synchronized with the subframe trigger signal of the DMD chip. This aligns the subframes of the phase-light modulator with those of the DMD chip. The beam modulated by the phase-light modulator is used as the backlight of the subframe, resulting in a better backlight effect and improved subjective visual experience. Without bias voltage adjustment based on the subframe trigger signal, different wavelengths of incident light require different mirror bias voltages for different subframe color channels, leading to errors in the phase modulation of the light and resulting in poor backlight modulation.

[0126] Based on the above, the present invention proposes a laser projection display system, such as... Figure 12 As shown, it includes an image processing module, a light source (including a red light source, a green light source, and a blue light source), a phase light modulator, a DMD chip, a mirror position and phase mapping adjustment module, a phase light modulator driving circuit, a DMD driving circuit, and a projection lens.

[0127] The light source is used to provide a light beam; the phase light modulator is used to adjust the phase of the light in the light beam provided by the light source; the DMD chip is used to modulate the light beam after it has been dimmed by the phase light modulator; and the projection lens is used to project the light beam modulated by the DMD chip into an image.

[0128] The image processing module obtains the brightness information of the input projected image by converting the RGB image to grayscale, provides digital signals to the phase light modulation device driving circuit to control the fluctuation state of the micromirror, and provides the R, G, and B three-channel image to the DMD driving circuit; the DMD driving circuit drives the R, G, and B three-color light source and provides the frame rate signal to the phase light modulation device driving circuit.

[0129] In embodiments of the present invention, such as Figure 13 As shown, the mirror position and phase mapping adjustment module consists of a micromirror structure setting unit 101, a micromirror actual height measurement unit 102, and a mapping unit 103. The micromirror structure setting unit 101 sets the micromirrors of the phase light modulation device into a high-low periodic structure. The low position corresponds to the height of the micromirror under the lowest-level driving signal, and the high position corresponds to the height of the micromirror under other driving signals besides the lowest-level driving signal. The micromirror actual height measurement unit 102 calculates the actual height of the micromirror under other driving signals besides the lowest-level driving signal based on the optical path difference of the beam under the high-low periodic structure. The mapping unit 103 finds the micromirror height where the actual height and the ideal height are within a defined error range, and establishes a relationship between the driving signal and its changed phase level based on the driving signal corresponding to the found micromirror height, so that the phase light modulation device modulates the height of the micromirror according to the relationship between the driving signal and its changed phase level. The ideal height is a group of micromirror heights that increases linearly with the driving signal.

[0130] In some embodiments of the present invention, the micromirror actual height measurement unit 102 calculates the actual height of the micromirror under all levels of driving signals except the lowest level driving signal by the following steps:

[0131] by Indicates optical path difference;

[0132] When the bright fringe condition Δ=mλ (m=0, ±1, ±2......) is met, the first distance D between the receiving screen and the phase light modulator, and the second distance L between the bright fringe and the zero-order bright fringe are measured; where h is the actual height of the micromirror, and d is the width of the micromirror.

[0133] The actual height of the micromirror is calculated by combining the optical path difference formula and the bright fringe condition.

[0134] In some embodiments of the present invention, when the mapping unit 103 searches for the micromirror height where the actual height and the ideal height are within a defined error range, it includes:

[0135] From 1 / 2, 1 / 4, ... up to 1 / 2 N The ideal height of the micromirror is determined step by step by setting the step size; among which, 2 N The driving signal level of the micromirror in the phase-modulated light device;

[0136] Find the actual height within the specified error range from the ideal height at each set step size;

[0137] If, within a certain set step size, the actual height and the ideal height of the micromirror do not meet the specified error range, the search ends and the actual height found in the previous set step size is taken as the final micromirror height.

[0138] In some embodiments of the present invention, the image processing module of the laser projection display system includes:

[0139] A brightness calculation unit is used to obtain a grayscale image of the image using a brightness method;

[0140] A phase distribution calculation unit, used to obtain the phase distribution of the image's luminance components on the phase mask surface of the phase-modulated device using the GS algorithm, includes:

[0141] The initial amplitude Ap of the beam on the phase mask surface of the phase light modulator is set to 1, and the initial phase φp is set to random.

[0142] Based on the diffraction formula, the phase φi and amplitude distribution Ai of the Imaging surface of the DMD chip are obtained. Only the phase information of the Imaging surface is retained, and the amplitude is set to the amplitude of the target image.

[0143] According to the inverse diffraction formula, the amplitude and phase of the returned phase mask are obtained; then the amplitude Ap of the phase mask is set to 1, while retaining the phase information.

[0144] Repeat the above two steps until the error limit is met or the maximum number of iterations is reached.

[0145] In some embodiments of the present invention, the laser projection display system further includes:

[0146] The subframe synchronization unit is used to design the subframe trigger signal of the phase light modulation device so that it is in sync with the subframe trigger signal of the DMD chip.

[0147] The specific display process of this laser projection display system has been detailed in the above display method and will not be repeated here.

[0148] It should be noted that, in the specific implementation process, the above-mentioned methods can be implemented by a hardware processor executing computer-executable instructions in software form stored in memory, which will not be elaborated here. The programs corresponding to the actions executed can all be stored in the computer-readable storage medium of the system in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0149] The computer-readable storage media mentioned above may include volatile memory, such as random access memory; may also include non-volatile memory, such as read-only memory, flash memory, hard disk or solid-state drive; and may also include combinations of the above types of memory.

[0150] The term "processor" as mentioned above can also refer to a collective of multiple processing elements. For example, a processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor, and it can also be a special-purpose processor.

[0151] It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A laser projection display method, applied in a laser projection display system, the laser projection display system comprising: A light source, used to provide a beam of light; A phase-modulated light device for adjusting the phase of light rays in a beam provided by the light source; The DMD chip is used to modulate the light beam after it has been dimmed by the phase light modulator. A projection lens is used to project and image the beam modulated by the DMD chip. The method is characterized by comprising: The micromirror of the phase light modulation device is configured as a high-low periodic structure; wherein, low corresponds to the height of the micromirror of the phase light modulation device under the lowest level driving signal, and high corresponds to the height of the micromirror of the phase light modulation device under other levels of driving signals besides the lowest level driving signal. Based on the optical path difference of the beam under the high and low periodic structure, the actual height of the micromirror under each level of driving signal except the lowest level driving signal is calculated; Find the micromirror height where the actual height and the ideal height are within a defined error range; wherein, the ideal height is a set of micromirror heights that increase linearly with the driving signal; Based on the driving signal corresponding to the found micromirror height, the relationship between the driving signal and its changed phase level is established; The height of the micromirror of the phase-light modulation device is modulated by the relationship between the driving signal and its changed phase level; Based on the optical path difference of the beam under high and low periodic structures, the actual height of the micromirror under each driving signal level other than the lowest-level driving signal is calculated, including: by Indicates optical path difference; When it meets When the bright fringe condition is met, the first distance D between the receiving screen and the phase light modulator, and the second distance L between the bright fringe and the zero-order bright fringe are measured; where h is the actual height of the micromirror and d is the width of the micromirror. ; The actual height of the micromirror is calculated by combining the formula for optical path difference and the condition for bright fringe.

2. The laser projection display method according to claim 1, characterized in that, Finding the micromirror height where the actual height and the ideal height are within a specified error range includes: From 1 / 2, 1 / 4, ... up to 1 / 2 N The ideal height of the micromirror is determined step by step by setting the step size; among which, 2 N The driving signal level of the micromirror in the phase-modulated light device; Find the actual height within the specified error range from the ideal height at each set step size; If, within a certain set step size, the actual height and the ideal height of the micromirror do not meet the specified error range, the search ends and the actual height found in the previous set step size is taken as the final micromirror height.

3. The laser projection display method according to claim 1, characterized in that, The method further includes: The grayscale image is obtained using the luminance method; The phase distribution of the image's luminance component on the phase mask plane of the phase-modulated device is obtained using the GS algorithm, including: The initial amplitude Ap of the beam on the phase mask surface of the phase light modulator is set to 1, and the initial phase Φp is set to random. Based on the diffraction formula, the phase Φi and amplitude distribution Ai of the Imaging surface of the DMD chip are obtained. Only the phase information of the Imaging surface is retained, and the amplitude is set to the amplitude of the target image. According to the inverse diffraction formula, the amplitude and phase of the returned phase mask are obtained; then the amplitude Ap of the phase mask is set to 1, while retaining the phase information. Repeat until the error limit is met or the maximum number of iterations is reached.

4. The laser projection display method according to claim 1, characterized in that, The method further includes: Design the subframe trigger signal of the phase light modulation device to be at the same frequency as the subframe trigger signal of the DMD chip.

5. A laser projection display system, comprising: A light source, used to provide a beam of light; A phase-modulated light device for adjusting the phase of light rays in a beam provided by the light source; The DMD chip is used to modulate the light beam after it has been dimmed by the phase light modulator. A projection lens is used to project and image the beam modulated by the DMD chip. Its characteristic is that it further includes: A micromirror structure setting unit is used to set the micromirrors of the phase light modulation device into a high-low periodic structure; wherein, low corresponds to the height of the micromirrors of the phase light modulation device under the lowest level driving signal, and high corresponds to the height of the micromirrors of the phase light modulation device under other levels of driving signals besides the lowest level driving signal. The actual height measurement unit of the micromirror is used to calculate the actual height of the micromirror under each level of driving signal except the lowest level driving signal, based on the optical path difference of the beam under the high and low periodic structure. The mapping unit is used to find the micromirror height where the actual height and the ideal height are within a defined error range. Based on the driving signal corresponding to the found micromirror height, a relationship between the driving signal and its changed phase level is established, so that the phase light modulation device modulates the height of the micromirror according to the relationship between the driving signal and its changed phase level; wherein, the ideal height is a group of micromirror heights that increase linearly with the driving signal. The actual height measurement unit of the micromirror calculates the actual height of the micromirror under all levels of driving signals except the lowest level driving signal using the following steps: by Indicates optical path difference; When it meets When the bright fringe condition is met, the first distance D between the receiving screen and the phase light modulator, and the second distance L between the bright fringe and the zero-order bright fringe are measured; where h is the actual height of the micromirror and d is the width of the micromirror. ; The actual height of the micromirror is calculated by combining the formula for optical path difference and the condition for bright fringe.

6. The laser projection display system according to claim 5, characterized in that, The mapping unit, when searching for the micromirror height where the actual height and the ideal height are within a defined error range, includes: From 1 / 2, 1 / 4, ... up to 1 / 2 N The ideal height of the micromirror is determined step by step by setting the step size; among which, 2 N The driving signal level of the micromirror in the phase-modulated light device; Find the actual height within the specified error range from the ideal height at each set step size; If, within a certain set step size, the actual height and the ideal height of the micromirror do not meet the specified error range, the search ends and the actual height found in the previous set step size is taken as the final micromirror height.

7. The laser projection display system according to claim 5, characterized in that, The system also includes: A brightness calculation unit is used to obtain a grayscale image of the image using a brightness method; A phase distribution calculation unit, used to obtain the phase distribution of the image's luminance components on the Phasemask plane of the phase-modulated light device using the GS algorithm, includes: The initial amplitude Ap of the beam on the phase mask surface of the phase light modulator is set to 1, and the initial phase Φp is set to random. Based on the diffraction formula, the phase Φi and amplitude distribution Ai of the Imaging surface of the DMD chip are obtained. Only the phase information of the Imaging surface is retained, and the amplitude is set to the amplitude of the target image. According to the inverse diffraction formula, the amplitude and phase of the returned phase mask are obtained; then the amplitude Ap of the phase mask is set to 1, while retaining the phase information. Repeat until the error limit is met or the maximum number of iterations is reached.

8. The laser projection display system according to claim 5, characterized in that, The system also includes: The subframe synchronization unit is used to design the subframe trigger signal of the phase-modulated optical device, so that it... It is at the same frequency as the subframe trigger signal of the DMD chip.

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